quote Originally posted by crzyone: I went to the dyno for a tuning session. This means taking a car with a standalong ecu and having it tuned. They come with a base tune, and this particular one was nowhere close to where it should be. I expected to spend 2-3 hours on the dyno with a laptop fine tuning my engine to get the most potential possible @ $200/hr. What I thought was a really bad tune turned out to be 2 dead cylinders which became more aparent as time went on. The car was making more and more power but was becoming rougher and rougher. We started pulling injector plugs and found 2 dead cylinders. The reason I did not fix the car at the dyno and continue is because I was booked in for a certain amount of time for tuning and that was it. Now I'm back at work and on my next days off I plan on going back with issues resolved and continue tuning. I won't stop until my car is making all the power it is supposed to be.

Crazyone, I apologize for hijacking your post and taking it over to the Tech Discussion but there was an opportunity to turn some good out of all that "stuff". Beautiful looking car by the way!! I must remember to have Ryan take some pictures of my dyno run!!

Here's my question to just the gentleman and ladies of the forum. My LS4 swap is getting dyno'd by Ryan this week. I'm starting this new post to actually get some good positive discussion on what to expect at the Dyno. I'm aware that there is a big differences between the horse power and torque numbers that are posted by car magazines and car manufacturers and the actual "at the wheel" horse power that the Dyno reports. In layman's terms, the higher hp is actually bhp?...which captures the raw power from the engine and the dyno hp is the net power after everything that causes friction between the engine and the wheels? I recall reading articles about this in magazine over the years. I guess the take away was that bhp is the way Detroit decided was the way to "normalize" the data for a apples to apples comparison. Far be it for me to challenge Detroit!

So if that's the case, I should always post two numbers right? The hp the engine was intended to make, and whatever improvement I am able to measure based on the tuning and mod work. The LS4 5.3L V8 from the Grand Prix is listed at 303hp. Ryan has done all kind of wonderful things to get more power out of the engine (within my budget). So is there a range or benchmark for the % one should expect a typical dyno will reduce as the power readout at the wheels?

I also understand that no two dyno machines are alike so you could feasibly get a different reading everytime you run one? If this is true, then dyno numbers are just a benchmark that lets you know if your tuning and tinkering improved it or worsened it? In that case, the only real number that means anything is either a 1/2 mile or 1/4 mile time...or a lap time at a known track. Am I thinking about that correctly?

Here's the deal. Can all Fiero enthusiasts share their starting points and experiences with their dynos? I'll definitely share the results from my LS4 swap. I have absolutely no problem with how MY car performs with MY engine choice with MY choice of builder, paid with MY money. I've learned so much from people on this forum and hopefully folks have learned something from my experiences with my swap.

So let's have it. I'm only really interested in folks who can share their actual experiences for learning and teaching. I'd remind folks that this is the TECHNICAL section. You're more than welcome to take the color commentary to the General Forum!

Blkcofy

quote Originally posted by blkcofy: I also understand that no two dyno machines are alike so you could feasibly get a different reading everytime you run one? If this is true, then dyno numbers are just a benchmark that lets you know if your tuning and tinkering improved it or worsened it? In that case, the only real number that means anything is either a 1/2 mile or 1/4 mile time...or a lap time at a known track. Am I thinking about that correctly?

You are correct in your thinking except that a track time doesn’t always mean much either. When a track gets too cold or hot you will loose traction which would have a negative effect on your track time. Also Temperature, Humidity and Barometric pressure have quite a bit of effect on power output of an engine which you would notice in your track times.

I used to go to a drag strip in Hawaii with a friend who bracket raced and you would notice the times getting quicker as the sun went down which brought the track and air temperatures down which meant more traction and more HP.

You are correct about different dyno's providing different results. Over on LS1Tech there are innumerable threads discussing the differences between Mustang and DynoJet power numbers. You also need to consider what correction factor the dyno operator uses. When GM dyno'd the LS4, they corrected air pressure, temperature and moisture content to SAE standards. Some dyno operators will correct to Standard Temperature and Pressure (STP), which I believe is a lower temperature and higher pressure standard than the SAE standard and will yield a higher power number.

I have a little project of my own on a LS4. While no head porting is included, there will be some upgrades to the valvetrain, exhaust system, an intake manifold, CAI and my own tuning efforts. My plan is to dyno once, completely stock and then again after all mods are in and I've retuned the engine. What really matters is what the change in delivered power is on the same dyno. I'm hoping for an additional 60HP at the wheels, but will be happy with 50 more.

I think that the drivetrain loss through the 4T65e-HD transmission, etc is usually estimated to be 19%. I've seen stock LS4 dyno sheets that ranged from 230whp (a 24% loss) to 252whp (a ~17% loss) but who knows if the variability is engine/drivetrain, correction factor used, or dyno or some combination of the three.

If you're doing multiple dyno runs over several day with different mods, you might want to have Ryan check to ensure that the dyno operator uses a consistent approach to applying correction factors.

Cheers

There are a couple different types of dynos. I only have have experience with a dynodynamics dyno which typically read lower out of all the dynos. These type are very good quality and quite consistant. When i first did a baseline dyno of my northstar the 3 runs almost completely overlapped each other.

I found that the tps enrichment was much to rich and the top end was a little rich as seen here.


I went back another day for some tuning and ended up with this


We ended up taking out some fuel and timing and dramatically reducing the tps enrichment. Sometimes strange things can happen on the dyno though. I'm running one of ryans 7730 setups and i dont have an emulator so i have to program a new chip each time between dyno runs. Because i was swapping chips every run i had the cover from ecm removed exposing the memcal and computer. The car was really leaning out run after run at just before 6000rpm and we couldn't figure out why. It never did it before. When watching the datalog you could see that the tps signal was going from 99% down to 37% at the same rpm everytime even when the pedal was floored, thus taking it out of power enrichment mode and skyrocketing the afr. This is the reason on the higher hp graph the power falls off earlier. Because i had the lid on the ecm removed, it was picking up electrical interference and causing weird things to happen. After i went home that day with the cover back on the ecm the problem went away. This is a note worth point if anybody plans to do tuneing on the dyno like this. If you're using an emulator i would reccomend shielding all the wires and the emulator itself.

Here is my car on the dyno last summer. I was doing a before/after test of the Trueleo headers. The drivetrain was a moderately tweaked 2.8 V6 and TH125 transmission, running on a stock Fiero ECM.



My target with this engine was 200 ft-lb torque at the flywheel, with peak torque coming in at about 3000 RPM. The result (with the Trueleo headers) was 160 ft-lb at the wheels, with peak torque coming in at around 3200 RPM. I'm not sure of the exact driveline loss, but if it's 20%, that would suggest 200 ft-lb at the flywheel.

By the way, the Trueleo headers improve torque above 3500 RPM, which is where the 2.8 needs it. The dyno chart showed the torque steadily increasing (over stock) from 3500 RPM up to the cut-off point.

Since then, I've installed a FWD Getrag and a modified 7730 ECM. So I'm probably getting more torque to the wheels now. And I'm definitely getting better fuel economy. One of these days, I'll hit the dyno again and find out. But I'm not in a big hurry. I enjoy driving my car. And that's all that really matters.

[This message has been edited by Blacktree (edited 03-18-2008).]

You all get positive feedback scores from me! Very helpful...very insightful! Thank you for restoring my faith!

More stories? More pictures of your car up on the dyno machine? It's amazing that there's so much variability in Dyno reads, but with each of your explanations, it's starting to make sense. You'd think it would be like a heart EKG monitor or blood pressure where you wouldn't have so many different inputs impacting an output that everyone compares and contrasts against. So if we NEVER compared car to car...which is how we get into so many debates...is there a rule of thumb that can be created in terms of % increase in power output for dollar spent or type of modification made (exhaust, porting, manifolds, ect.?).

[This message has been edited by blkcofy (edited 03-18-2008).]

From a few months ago...
https://www.fiero.nl/forum/Forum2/HTML/087194.html

Make sure you show them how to release the ebrake. :-D


Here is my EBRAKE run:


.. and here's how much power it put down after I made them retest it after pulling it out of the shop to find my rotors were blue:
The 10 ft-lb dip around 3600 rpm is from poor tuning at that RPM. The AFR was around 10:1 or 11:1 there. I haven't had a chance to fix that yet because the car hasn't spent much time on the road.


I convinced them to give me the run for free since it was of equal cost to a new pair of rotors for the rear. They did three or four runs with the ebrake on... they got hot and blue.

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1988 Pontiac Fiero 3.4 DOHC V6 5-speed
California Smog Legal!

[This message has been edited by Steven Snyder (edited 03-18-2008).]

Different dyno's have different means on how they load the vehicle which accounts for why some dyno's like the dynojet read higher than the mustang dyno. A dyno actually does not read hp, It reads the torque and calculates the hp. Atmospheric conditions, what gear the vehicle is in, and the correction factors all play a part in what the output is. You could dyno the car on a dry 50* day then dyno it on a 70* humid day and get two different readings. The correction factors are suppose to compensate for these difference's but that does not mean the engine is going to adjust to the same levels as the correction factors. The other thing is GM rates there engines under the SAE specs, But generally it is a sample of only a couple of engines. Since the engines are mass-produced and tolerance's vary, Your particular engine could have anywhere from 290 to 315hp. Finally, the original tune of the engine that GM uses is designed to be a general tune for all engines and conditions, Ryan has a lot of experience getting the engine tuned for peak performance so you may actually gain a few hp from that as well. Even some stock vehicles can gain a few hp from just tweeking the tune.

As for whp vs bhp, That is determined by the driveline loss (everything from the flywheel to the tires) Typically a longitudal set-up has higher losses than a transaxle.
As an example when I did my 3.4L and had the trans rebuilt, they dyno'd the trans by itself and came up with a 17% loss thru it. After everything was put together and the vehicle was run on a chassis dyno I had about an 18% driveline loss, But that was only calculated based on the original engine dyno and trans dyno's and what we saw on the chassis dyno.

Based on the rated power of my V-8 I have roughly a 12.5% loss thru the manual. Typically for longitudal set-ups they use 18% for manual and 25% for auto. For transaxles they typically use 15% and 20% respectively.

As for the difference's in dyno's, The Dyno-Jet is noted to give you what the max power is with the vehicle in a static state. It is said to be a good tool for calculating driveline loss when compared to the engine dyno. The Mustang dyno is noted to be more accurate in terms of the vehicle traveling down the road. That is the most popular explaination of the difference's.

Track times like dyno's can vary depending on atmospheric conditions as well as vehicle traction, track conditions, engine and trans temp, etc.
The 60 foot times will let you know how well you launch and your traction off the line.
The 1/8 mile time and MPH will let you know how well your torque is pushing the car.
The 1/4 mile time and the MPH will let you know how well the horsepower works.
Your transaxle gearing also has an effect on MPH thru the different times as well. Lower gearing will slow you down a little during the first 1/8 mile but make up for it during the last 1/8 mile. Taller gearing will speed up the first 1/8 mile but be slower the last 1/8 mile typically. Your engines power band and the shift points can make a difference as well.

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Happiness isn't around the corner...
Happiness IS the corner.
ZZ4 Powered !!

[This message has been edited by Oreif (edited 03-18-2008).]

It don't really matter much that dynos will give slightly dif results unless peak numbers is you care about. They are just a tool (or gauge) that lets you see what you have gained or lost with your mods etc. As long as you have a wideband reading your A/F you should be able to get the job done right on any dyno. Never tune without reading A/F ratios, or even look at HP numbers. Lean fuel mixes can make power and ruin engines.

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[IMG]



Trueleo.com/fiero.htm
RSpiderII@aol.com

quote Originally posted by Steven Snyder: Make sure you show them how to release the ebrake. :-D

Both the dyno operator and I forgot to take the ebrake off for the first run. I lost about 60hp on that run. Luckily nothing was damaged. Felt kind of stupid though,

The type of chassis dyno blkcofy's car will be strapped to is a MUSTANG dyno. I will do my best to encourage the dyno operator to accurately set up the machine, but ultimately it's their machine and I really have no say in what settings get put into it. The most I can do is ask.

I've run cars on many different dynos and been present at many dyno sessions. One constant that stands out overall is no two dyno runs are going to be identical, especially when different brands of dynos are used or there are different people running the machine. As correctly mentioned earlier, a chassis dyno is really designed to be a tuning tool. If you are looking for the most accurate measurement for your engine's power, you really need to remove it from the car and have it put onto an engine dyno. But even then you are still going to run into differences depending on the machine and operator.

That's why I put more stock in 1/4 mile runs. Sure, changing weather and track conditions can affect the results, but a 1/4 mile run at the dragstrip gives you a better overall picture of straight-line performance of the entire vehicle. Chassis dyno sheets are nice to put on the wall or show off to your friends, but in my opinion, the 1/4 mile timeslip gives you a much more accurate assessment of the vehicle's performance. After all, a 500hp engine isn't going to mean much if you can't get that power to the ground.

Now concerning the HP ratings and such, there are a couple of different standards out there. SAE certified standards are the latest offerings from car manufacturer's who want to pay for the certification. Those dyno tests are performed in strictly regulated conditions and usually involve having all assy's mounted to the engine and functioning during the testing. These HP and TQ numbers tend to be the lowest you will see out of all types of engine dyno results. Before the SAE certified tests became widespread in use, most car manufacturers were using a testing standard that was similar to the SAE tests just without the certification. They still had everything installed and hooked up to that engine as it would be in the car.

But back in the old days, manufacturers (and even most companies selling crate motors today) ran engine dyno tests with the minimum amount of assy's mounted on the engine. Also these tests were usually run with optimal induction and exhaust systems. Obviously this produced the highest HP and TQ numbers, which is great for marketing. But the problem with this type of dyno test is it doesn't tell you how this engine is going to perform as-installed in the car. Which means if you ordered a 400 HP crate engine, if that engine wasn't dynoed to SAE specs, it probably isn't going to make 400hp after you install it into your car. That's why a lot of auto manufacturers eventually went with the SAE-type testing conditions.

The good news is GM paid for the SAE certified dyno tests of the LS4 engine so we can expect a stock LS4 is going to make 303hp and 323tq at the crank when installed in a vehicle with all the stock emissions and assy equipment hooked up to it. Obviously some upgrades have been made to the engine, induction, and exhaust systems in blkcofy's swap; so we expect to see improvements in overall power output. But again, the numbers we are going to see at the upcoming chassis dyno test are only as good as the testing equipment's calibration. Remember, I don't own nor am I allowed to operate the dyno testing equipment so I have no control on how it is set up. I can only make "requests". I think the true measure of this car's performance will be found once it goes to the dragstrip.

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power corrupts. absolute power corrupts absolutely.

Custom GM OBD1 & OBD2 Tuning | Engine Conversions | www.gmtuners.com

The real key item for your first dyno experience is to realize that no matter what your output will be lower than what you expect. If you go with that mentality you will come out very happy. I laugh to see most dyno post come with dozens of excuses of why it wasn't higher (except for few real cases) like these dynos read low, fuel was hot, the dyno fan was off, the ground cable had rust, it was not calibrated, yada yada yada. The key item is that you have a baseline to improve. Just accept it and move on. On my first session it was lower than I thought too. But I had my baseline and goal. On second session I had 62hp more after mods and then gained 6hp more after tuning. So there was progress. Again, remember that it will be lower than what you think. Good luck

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Red: TPI V8 + 6-Speed Yellow: Nitrous 3.4 + 4 speed Auto
304rwHP/366rwTQ

quote Originally posted by Oreif: Finally, the original tune of the engine that GM uses is designed to be a general tune for all engines and conditions, Ryan has a lot of experience getting the engine tuned for peak performance so you may actually gain a few hp from that as well. Even some stock vehicles can gain a few hp from just tweeking the tune.

I would like to expand on this a little if I may. Anyone who has done custom tuning on stock engines has undoubtedly noticed that the manufacturer tends to make the A/F mixture more rich that what is considered to be "optimal" for maximum power at full throttle. Why? Well the main reason is piston protection. The A/F ratio is purposely set overly rich to keep the pistons cool. The industry's accepted AFR for maximum power out of naturally aspirated engines is about 13.0:1 and 12.5:1~12.0:1 for boosted engines depending on the setup. While these numbers tend to work good for most engines to make maximum power, they aren't necessarily correct for all engines and all conditions. For example, my Turbocharged 3800 does not make maximum power with an AFR of 12.5:1 as measured with a wideband O2 sensor. It seems to make the most power if the AFR is running at 11.5:1.

I did a dyno tuning session for a customer some time ago using a completely stock engine. He wanted to squeeze the maximum amount of power out of his naturally aspirated engine as possible. The baseline dyno run revealed AFR's of 12.3-12.5:1 with stock programming. I adjusted the tune so his AFRs stayed at ~13.0:1 during the dyno pull to show him that his engine only picked up 2hp and 3 ft/lbs of torque. Since this wasn't much of an improvement, I suggested the AFR be richened back up slightly to keep some of that (factory built-in) piston protection. So we put the AFR at about 12.7-12.8:1 and called it a day. I don't like tuning engines within an inch of their life. You never know what kind of conditions the engine/vehicle is going to have to endure out on the road so I always like to build in a little safety net if I can. I've also noticed that changing weather conditions do impact EFI systems much the same as they do carb setups. Most EFI systems can do a decent job of compensating for this but things do still change (like AFR and ignition timing requirements). The best thing any tuner can do is set up the tune to work the best for the expected wide array of operating conditions the vehicle is going to be exposed to out in the real world. I've done the same with blkcofy's tune because I know it's more important to him that this powertrain last a long time than make that extra 2 or 3 hp.

-ryan

[This message has been edited by Darth Fiero (edited 03-18-2008).]

Just wanted to add, that being an amateur mustang dyno operator myself, it is VERY hard to make them lie as the main correction factor is calculated by sensors onboard the dyno head. Some of the acceleration and load factors can be jimmied if you do not input the correct vehicle data, but those functions are mostly for tuning and simulation, not fancy charts.

quote Originally posted by ryan.hess: Both the dyno operator and I forgot to take the ebrake off for the first run. I lost about 60hp on that run. Luckily nothing was damaged. Felt kind of stupid though,

pwned! I lost exactly the same amount of power. Guess we know how good the ebrake is..

quote Originally posted by Darth Fiero: Anyone who has done custom tuning on stock engines has undoubtedly noticed that the manufacturer tends to make the A/F mixture more rich that what is considered to be "optimal" for maximum power at full throttle. Why? Well the main reason is piston protection.

That's one of the reasons it makes me nervous to hear people installing aftermarket ECMs (Megasquirt, Holley, etc) on Northstars. A stock northstar runs pretty rich as you said, around 12:1 at WOT. But after a certain amount of time at WOT, it will change the AFR to 10:1 to cool the piston crowns. Power and fuel economy do take a hit. No one in their right minds are going to tune a N/A engine @ 10:1 WOT. So that means those running those aftermarket ECMs are running the risk of catastrophic engine failure.

The only two computers I'm aware that allow this WOT AFR change are the 7730 and stock N* computers. I would imagine many other engines have similar protection schemes, especially those with high specific outputs >1HP/CI.

quote Originally posted by Steven Snyder: pwned! I lost exactly the same amount of power. Guess we know how good the ebrake is..

Yeah, I probably should upgrade those rear brakes one of these days...

[This message has been edited by ryan.hess (edited 03-18-2008).]

I had my SBC car dynoed late last year, it was on a Mustang Dyno, and to be honest I was disapointed with the results (235hp and 275ftlbs torque) considering the spec of the engine, however as stated before it does now give me a baseline from which to work. And looking at the car now it seems that maybe my exhaust is strangling the engine, as it has some very tight bends in 2.25" tubing made up by the local Tuffy store, so I will hopefully have a new exhaust soon using 2.5" mandrel bends with a bit more thought to the routing. And as I have a baseline I will be able to see the result, hopefully an improvement.

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84SE, aero body, 4 speed and an injected 355 V8

Positive feedback ratings for everybody...I'm in a generous mood and I'm thrilled with both the positive and friendly comments!

Now all I need are pictures of cars on dyno machines!!

Has anyone done 1/4 mile runs in conjunction with running on a dyno to be able to link particular readings with actual performance?

Blkcofy

quote Originally posted by blkcofy: Has anyone done 1/4 mile runs in conjunction with running on a dyno to be able to link particular readings with actual performance? Blkcofy

I don't quite know what you are asking exavtly, but I had ny Fiero dynoed and on the track within a couple of weeks. Weather was similar and mods were exactly the same. You can see the results in my sig.

I tried to do this as soon as I could after I got my swap back from Ryan. I wanted to know where I was at performance-wise (1/4 mile) and how much more I could squeeze out of it (dyno, with a wideband (running quite rich)). I'm upgrading injectors and going down in pulley size this year and will be getting a new tune. After I'm done, I will take it to the same dyno to guage where I'm at. I will also have it on the track as soon as I can. I like having dynosheets and 1/4-mile slips to show my progression.

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'88 GT- 257rwhp 319rwft/lbs 12.95@106.1mph

My car dyno'd 309 rwhp 349 rwft/lbs on a DynoJet and it runs 12.36 @ 111.6 mph.
Based on dyno comparisons I have seen/read my car should dyno around 287 rwhp on a Mustang dyno.
So far from what I have seen/read the Mustang dyno's read around 10% less than a dynojet. I do not know how accurate that really is, I'm just going by what I have seen on other forums discussing the difference's.

As another reference, When I had my 3.4L with a carb, (auto trans)
On an engine dyno I had 223 hp
On a dynojet I had 197 rwhp
the car ran 14.26 @ 94.3 mph in the 1/4 mile.

The EFI 3.4L (with 5-spd) on a dynojet had 205 rwhp
It ran 13.77 @ 98.1mph in the 1/4 mile.


AkursedX ~ Just out of curiosity do you know if it was a dynojet or a mustang dyno?

[This message has been edited by Oreif (edited 03-19-2008).]

quote Originally posted by Oreif: AkursedX ~ Just out of curiosity do you know if it was a dynojet or a mustang dyno?

I honestly don't know for sure since Livernois Motorsports has both a Dynojet and a Mustang Dyno and my printouts don't indicate anything. But if I were to guess, I'd say that it was a Dynojet. I saw pictures of the Mustang dyno online and I don't think I was in that part of the building.

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'88 GT- 257rwhp 319rwft/lbs 12.95@106.1mph

My experience with a Dynojet and Dynapacks was very close. This was with both my car and a friends LS1 equipped Sonoma. My car made 387 on the Dynojet and 415 on the Dynapack (415 was with more tuning). The Sonoma made around 400 on both setups. The absolute number isn't critical, it is just the difference from modifications (although it feel good to get the number you are after!).

You 1/4 MPH is a very good indication of HP. I was trapping 116.5 MPH while at 387 WHP and 118 MPH at 415 WHP.

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62 Buick Special
86 GT, 5-Speed
87 GT, 3.4l DOHC Turbo 415 WHP, 11.9 @ 118
88 Toyota Supra Turbo

quote Originally posted by Oreif: My car dyno'd 309 rwhp 349 rwft/lbs on a DynoJet and it runs 12.3 seconds. Based on dyno comparisons I have seen/read my car should dyno around 287 rwhp on a Mustang dyno. So far from what I have seen/read the Mustang dyno's read around 10% less than a dynojet. I do not know how accurate that really is, I'm just going by what I have seen on other forums discussing the difference's. As another reference, When I had my 3.4L with a carb, (auto trans) On an engine dyno I had 223 hp On a dynojet I had 197 rwhp the car ran 14.2 in the 1/4 mile. The EFI 3.4L (with 5-spd) on a dynojet had 205 rwhp It ran 13.7 in the 1/4 mile. AkursedX ~ Just out of curiosity do you know if it was a dynojet or a mustang dyno?

This post is useless without traps......

quote Originally posted by Darth Fiero: The type of chassis dyno blkcofy's car will be strapped to is a MUSTANG dyno. I will do my best to encourage the dyno operator to accurately set up the machine, but ultimately it's their machine and I really have no say in what settings get put into it. The most I can do is ask. I've run cars on many different dynos and been present at many dyno sessions. One constant that stands out overall is no two dyno runs are going to be identical, especially when different brands of dynos are used or there are different people running the machine. As correctly mentioned earlier, a chassis dyno is really designed to be a tuning tool. If you are looking for the most accurate measurement for your engine's power, you really need to remove it from the car and have it put onto an engine dyno. But even then you are still going to run into differences depending on the machine and operator. That's why I put more stock in 1/4 mile runs. Sure, changing weather and track conditions can affect the results, but a 1/4 mile run at the dragstrip gives you a better overall picture of straight-line performance of the entire vehicle. Chassis dyno sheets are nice to put on the wall or show off to your friends, but in my opinion, the 1/4 mile timeslip gives you a much more accurate assessment of the vehicle's performance. After all, a 500hp engine isn't going to mean much if you can't get that power to the ground. ..... I think the true measure of this car's performance will be found once it goes to the dragstrip.

I'm going to go out on a limb here and make a WAG about this vehicle's potential performance on the strip.

Assumptions:

1 Weight transfer in a RWD application of this drivetrain is going to allow the vehicle to launch harder than a FWD application. The LS4 has tons of low RPM torque, and a fairly low first gear, traction is a huge issue on the FWD's
2 Crank HP is close to the 340HP BLKCOFY speculated on in another thread; this may translate into ~275 WHP.
3 Weight with driver equals 2900 pounds.
4 ET and MPH calculators that you can find on the web have some relationship to reality (really speculative assumption)

The calculators I used (from http://www.golenengineservi...tml/calculators.html ) gave a result of 11.9 @ 114.8 using these assumptions.

Sanity check:
The same calculator came up with 13.77 @ 99.3 for the ~4000lb (including driver) vehicle that this drivetrain came installed in. This is within the range of timeslips I've seen posted in other forums, so maybe.

It would be cool to see a nearly stock LS4 running in the 11's (and getting 30+ mpg on the highway). Good luck when you get to the track, I'll be pulling for you.

Cheers

I think we would all love to run 11's with our 300ish HP motors, but sadly thats all just a paper race.

Every fiero with a 4t65e and 250-280 WHP is going to run a high 12. The LS4 is going to be significantly slower due to the torque and power curve losses from not being boosted compared to mine and akursed 1/4 runs. If he makes a significantly higher (20-30whp) more power on the dyno than we do, then he should expect about the same times we put down.

quote Originally posted by blkcofy: Positive feedback ratings for everybody...I'm in a generous mood and I'm thrilled with both the positive and friendly comments! Now all I need are pictures of cars on dyno machines!!

Why pics when a video with sound is much better

[QUOTE]Originally posted by Alex4mula:


Why pics when a video with sound is much better

[QUOTE]

I'm green w/ envy and full of jealousy! Your car sounds wicked! That's got to be worth at least 2 or 3 hp from the sound alone! Okay, maybe not.
I just can't wait to get my car back!! The crappy weather is making it easier to get by without it, but when the sunshine finally breaks through...yeah boyeeee!

[This message has been edited by blkcofy (edited 03-19-2008).]

quote Originally posted by darkhorizon: This post is useless without traps......

3.4L carb with auto = 14.26 @ 94.3 mph
3.4L EFI with 5-spd = 13.77 @ 98.1mph
V-8 with 4-spd = 12.36 @ 111.6 mph

Also edited my previous post as well.

[This message has been edited by Oreif (edited 03-19-2008).]

quote Originally posted by blkcofy: Thanks TiredGXP! I've certainly learned alot from you and your crew at LS1 Tech. You guys have welcomed both myself and Ryan with this project. If I'm anywhere close to your WAG, I'll be fit to be tied! I might even change my signature to "GXP Superstar" and set my theme music from Lupe Fiasco's album track with Matthew Santos! The boys in my BMW club are going to crap on themselves when they see this Fiero pull away from them on the back stretch at Mid Ohio this summer !! Absolutely crap on themselves !! Edit: What's your thoughts on the $$$ I invested in the performance rebuild kit on the 4T65e HD tranny and electronic paddle shift kit Ryan installed? That combined with the HP Tune Ryan is doing to rev at the optimal rpm points should work in my favor to get close to achieving a sub 12 second time....that and good tires and driving skill, I suppose! None of this can be captured on a Dyno, so the real judge will be a drag strip, huh.

Thanks. I have to admit that I find people on this board to be much more adventurous and creative when it comes to modifying their cars than the LS4 crowd on other forums. I suspect that this is due to the relative cost of a GXP vs a Fiero. When I bought mine in 2005, the MSRP was $43,000 CDN (our dollar was $.65 US at the time, but by the time you finish bargaining with the dealer the price droped to the equivalent of $23,000 US). It's really hard to make yourself do anything too wild to a new car while it's under warranty .

The performance rebuild kit is money well spent. I don't remember, did that kit also include the stronger input shaft? As far as the paddle shifters go, you'll probably find them to be useful on the track. There's really no reason to use them on the street or drag strip, just set your shift points and let the computer do the shifting - it's going to hit the shift points more consistently thay you can manually. I rarely use the paddles, mostly just to gear down on steep hills to save the brake pads or to start in second gear when it's icy.

Just FYI, I'm getting real close to fitting a LS6 intake onto a LS4, There's a thread about that on LS1TECH, I've found a workable solution for the interference with the oil pressure sending unit and the DOD connector. Since Ryan eliminated the power steering pump, you don't have to deal with mods to the rear of the intake, so this could be an easier swap for you than on the FWD cars. I figure this swap is good for a minimum of 15 more whp, probably more.

Oh, yeah, check out this link to gm's dyno chart for the stock LS4 - http://media.gm.com/us/powe..._LS4_Impala%20SS.pdf - now that's a flat torque curve, over 300 ft lb from 2000 rpm to 5000 rpm. I wonder if the porting job Ryan did will eliminate the slight drop over 5000 rpm, I look forward to seeing the results of the dyno run.

Cheers

[This message has been edited by TiredGXP (edited 03-19-2008).]

quote Originally posted by Alex4mula: Why pics when a video with sound is much better

NICE!!!

edit: 97 stock northstar engine, spec aluminum flywheel, 1.5" shorty headers, dual 2.5" exhaust into single 3" spintech muffler with dual 2.5" outlets, 7730 ecm. New mods since then are CHRFab valve springs and retainers, 1.75" long tube ~equal length (36in) headers, backcut intake valves, Cometic MLS head gaskets, ported and polished cylinder heads and it's getting bored .020" over.

[This message has been edited by Zac88GT (edited 03-19-2008).]

Care to post any details on that? It sounds really great.

The dyno results are in but before we get to those, let me explain a couple of things. As stated before, the dyno we ran this car on was a Mustang dyno which tends to produce lower WHP and WTQ numbers than the more popular Dynojet dyno. Secondly, I factored the total vehicle weight with driver and full tank of gas to be 3300 lbs. I know this sounds a lot to some of you, but I think some of you people who think an all-aluminum V8 is light are mislead. I weighed every part of this engine from the shortblock to the heads, intake, assy's, etc and added up all the pieces that would be installed on it once it was in the car. And the weight figure I came up with was about 480 lbs give or take a bolt or two. That's just the engine, the 4T65-E auto trans weighs in at 214 lbs. So needless to say this combo weighs more than my 3800/4T60-E which is in a base coupe, and that car tipped the scales at 2920lbs with 1/2 tank of fuel and me not in it.

We executed 4 dyno runs today including a 1/4 mile simulation. For some reason the dyno would only spit out RAW, UNCORRECTED numbers so the HP and TQ numbers it produced were much lower than everyone expected. However, the simulated 1/4 mile run is about right on with what I estimate this car of being able to do...







Again, these are uncorrected raw results. I'm sure the power numbers will look better once they are corrected for the conditions in the dyno cell, which weren't that great. I have a scan log for the runs and the intake air temp sensor was reporting 90 deg air entering the engine (was actually about 60 deg in the dyno cell but 3 small fans blowing on the front of the car couldn't do much to get clean air into the engine) and I estimate the humidity was probably somewhere in the 70-80% range.

If we want to see higher numbers this car can be taken to a DynoJet or other brand chassis dyno so we can get a more impressive graph. But the simulated 1/4 mile run sounds about right for what this car should do based on what that Fiero swap I did a while back using a 260hp Iron-head LT1 that produced a 13.2 @ 100mph timeslip with a 4T60-E auto at the dragstrip. This car does feel faster to me than most of the 3800 SC swaps I have done, even those heavily modded.

[This message has been edited by Darth Fiero (edited 03-19-2008).]

quote Originally posted by Alex4mula: The real key item for your first dyno experience is to realize that no matter what your output will be lower than what you expect.

No truer words were ever uttered in the history of modding Fieros. I'm not going to act like I'm not sorely disappointed, having read the result with the rest of you.

I'm sure Ryan will help pick my spirits off the floor and help me understand the difference between a 2005 Pontiac Grand Prix GXP with a curb weight of 3600 lbs (I'm assuming no driver weight added) with dyno reads between 235-254 whp and 6100 rpm redline, and 1/4 mile time 14.3 @ 98.1mph --> yet on a Fiero with original weight of 2790 lbs and all the performance mods on top, comes up with only 210 whp at 5250 rpm. I tried to keep on reading the post about something with uncorrected number, raw, humidity, but the words got all blurry so I stopped reading. Probably the tears swelling up in my eyes...

I had prepared myself for at least matching the stock numbers of the Grand Prix, but would have never imagined it would be this bad. Bad might be a poor choice of words, but this is like hearing your dog got hit by a bus on the evening news while you thought all along it was siting on the porch chewing on the t-bone you left him in his bowl.

I think I need to go lie down for awhile...I'm feeling nauseous.

Happy Easter.

quote Originally posted by blkcofy: No truer words were ever uttered in the history of modding Fieros. I'm not going to act like I'm not sorely disappointed, having read the result with the rest of you. I'm sure Ryan will help pick my spirits off the floor and help me understand the difference between a 2005 Pontiac Grand Prix GXP with a curb weight of 3600 lbs (I'm assuming no driver weight added) with dyno reads between 235-254 whp and 6100 rpm redline, and 1/4 mile time 14.3 @ 98.1mph --> yet on a Fiero with original weight of 2790 lbs and all the performance mods on top, comes up with only 210 whp at 5250 rpm. I tried to keep on reading the post about something with uncorrected number, raw, humidity, but the words got all blurry so I stopped reading. Probably the tears swelling up in my eyes... I had prepared myself for at least matching the stock numbers of the Grand Prix, but would have never imagined it would be this bad. Bad might be a poor choice of words, but this is like hearing your dog got hit by a bus on the evening news while you thought all along it was siting on the porch chewing on the t-bone you left him in his bowl. I think I need to go lie down for awhile...I'm feeling nauseous. Happy Easter.

I feel your pain, blkcofy. I was shocked when I saw these dyno numbers as well. But after watching the results spew out of the dyno's computer (and in the manner they were coming out and being displayed), my shock was quickly replaced with: WTF is wrong here? I spoke to the dyno operator about my concerns with the low HP and TQ test results and he told me the machine was only putting out RAW, uncorrected numbers. He also said the dyno test we did that showed the 210 whp and 232 wtq numbers was a "sustained power reading" which did not show peak power numbers. What does that mean? I don't know. I haven't ever worked with a Mustang Dyno before so I cannot tell you what was wrong. Perhaps the machine wasn't set up correctly to display the "corrected" numbers we were looking for. And what made things more confusing was the fact the simulated 1/4 mile run looked dead on with what I was estimating this car would do. But there's certainly no way a car only producing 210 whp is going to do 12.6 sec in the 1/4 mile; I think we can all agree on that. I did see the computer display 283 WHP and 303 WTQ numbers after we executed that 12.6 1/4 mile run, but the dyno operator couldn't get the machine to print those numbers onto paper.

Tell you what, I'm so disappointed in these results myself that I am going to give you a call and discuss the option of taking your car to that other dyno in town.

-ryan

3,300 pounds with driver, huh. Yeah, I really underestimated the total weight. After I posted that, I remembered this thread: https://www.fiero.nl/forum/F...2/HTML/089803-2.html . If you ignore all the "flaming" that went on, ultimately there were several vehicles, both V6 and V8, that came in around 3100#, plus driver. I guess I have to get the myth of the 2700# Fiero out of my head

Still, the dyno simulator for the 1/4 was pretty good, mid 12's on a basically stock motor, a mere second or so faster than my car! I look forward to hearing how it does on the road course and on the dragstrip.

For those who may be intested, there's a really good write-up about dyno correction factors, density altitude, and some java applications to calculate what the dyno correction factor may be for any given altitude and weather condition at: http://wahiduddin.net/calc/cf.htm . If you want to play around with it, NavCanada provides the required altimiter settings, dew points... at: http://www.flightplanning.n...age=lab&TypeDoc=html (I assume that NOAA has a similar site). You just need to enter your local airport's code, and select "Plain language" for the"METAR" data.

BTW, the calculator used yesterday comes up with 12.43 @ 110.0 when using a 400# heavier vehicle weight, .2 sec and 2.3mph more optimistic than the dyno run.

Cheers

[This message has been edited by TiredGXP (edited 03-19-2008).]

3300 lbs probably isn't too far off of what it actually is, but it may be a little high. My N* 6spd GT weighed in at 2900 with half a tank of fuel and no driver. I think the northstar may be a little heavier but the 6 spd a little lighter. I'd say (depending on driver size of course) between 3150-3300 with driver and full fuel.

quote Originally posted by Oreif: As another reference, When I had my 3.4L with a carb, (auto trans) On an engine dyno I had 223 hp On a dynojet I had 197 rwhp the car ran 14.26 @ 94.3 mph in the 1/4 mile. The EFI 3.4L (with 5-spd) on a dynojet had 205 rwhp It ran 13.77 @ 98.1mph in the 1/4 mile.

I did some reading on these engines (here for reference). Those are great #'s for a 3.4 pushrod. I see the EFI was with the trueleo intake, but done with sprint headers (before the trueleo manifolds were around). Does the owner still have that car, or someone with a similar setup (272 cam, bumped up compression) have both the trueleo intake and exhaust?

And thanks to blkcofy for making this thread. It's helpful to see all these #s in one place If someone wants to do an engine swap, dyno curves and 1/4 mile times are a good way to see if the engine they're considering will fit the characteristics they're looking for, IMHO.