I wouldn't worry about it too much blkcofy. Those readings definietly seem strange. Let's just say that mph in the 1/4 mile time is accurate. I've run a 107mph trap time with a 256whp and 319wft/lbs dyno in a car that weighs just about the same with the same trans.

As for the weight, I'd say that's close, maybe on the high side, for a fiero with driver. I figure I'm around 3200lbs with 245lbs of driver inside of an '88 gt with an l67 and 4t65e-hd.

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

quote Originally posted by Zac88GT: 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.

I ran mine the other day
The LS1 PCM that was tuned and sent to me made 221 RWHP
One of my tuned Northstar PCM's made 239.9 RWHP

I also took a 2003 Cadillac DHS and it struggled to make 200 RWHP!

This was all on a Dyno Dynamics Dyno. I believe that they are one of the best Dyno's on the market. Yes the Numbers are low, Just like you said. I was told 13% off from a Dyno Jet.
The 2000 to 2003 Northstars usually come out at 225RWHP. you take that 200 and add 13% guess what you get.

Now my LS1 PCM. I have not looked at the program or the data other than my fuel trim is -15%. This program does not use an EGR and the guy that sent me the PCM may have jack the timing up even more than it already was. I need to stop driving that car before I hurt the engine.

You are my hero. I wish you had my PCM instead of The commodore 64

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. If you go with that mentality you will come out very happy.

Isn't this the truth. I tried to guess low, I would have been happy with 260 at the wheels but I ended up with 175. My next tuning session on 8 cylinders should be much more productive.

Hey, atleast my 6cyl N* makes about the same power as a 3.4dohc

So without dragging 2 cylinders and more dyno tuning I should be 260+hp.

Ryan, I did notice that my AFR on the bank that was running properly was close to 10:1 at WOT. When I go back for further tuning I will lean it out to around 12:1. I can't see being at WOT long enough to do damage to the pistons.


Good thread, good discussion. +s for you guys for keeping a dyno thread civil. This should encourage more fiero owners to post their dyno results or book dyno appointments to help them tune their engines.

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Buy a fiero, become a mechanic
3.4 dohc Install
Sub Install
Northstar Install

I thought I'd post this up to demonstrate how much difference a correction factor can make. A little bit of background on the following charts: The E40 ECM on the 2005 LS4 allows you to log a "delivered engine torque" PID. I'm not sure how the ECM determines what the value should be, I've heard that there is a piezeo-electric sensor that delivers a signal, but can't confirm it, so this might just be an estimator that the GM engineers programmed into the operating system.

At any rate, last September I was logging delivered engine torque, and was playing around with simulated dyno charts based on that data. I used weather data and correction factor calculators that I posted up earlier to determine what the SAE correction factor would be. At any rate, I live at about 2200' altitude, intake air temperature recorded in the data log that formed the basis of this chart was ~77*F. Unfortunately I did not record the dew point or altimeter setting, so I can't reproduce the calculation. In any event, the calculated correction factor was 1.094.

The engine has an SAE rating of 303 HP @ 5600, 323 ft-lb @ 4000
Raw data logged provided 287 HP @ 5358, 313 ft-lb @ 4186
Corrected data provided 313 HP @ 5358, 342 ft-lb @ 4186

Engine had a home grown tune using HPT and a K&N drop in air cleaner for mods.



I make no claims that this is the actual crank power delivered by the engine, this chart is just to show how significant a difference the correction factor can make. It is kind of neat that you can use a scan tool and excel to build something like this though.

Cheers

quote Originally posted by kwagner: 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.

Yes, The owner still has the car. It's his daily driver. As for gains going to the Trueleo exhaust, I would guess he may get a few more ponies out of it. The Sprints are not bad for a performance manifold but obviously a better set of headers would help. I just don't know by how much.


As for this thread, Based on the engine rating of the LS4 I would have guessed a mid-12 second car as well. I just happen to find it strange that the dyno read so low for the power run.

Ryan,
Do you happen to know if there was a gear difference between the power run and the 1/4 mile test? I don't know the ratio's of each gear in the transaxle, But from the huge difference between the 283whp shown on the 1/4 mile run and the 210whp I wonder if the readings were from different gears. It would be interesting to see what it does on a different dyno.


blkcofy,
I would not get too upset over the dyno power results. These two statements from Ryan's posts should keep your spirits up:
"This car does feel faster to me than most of the 3800 SC swaps I have done, even those heavily modded."
"I did see the computer display 283 WHP and 303 WTQ numbers after we executed that 12.6 1/4 mile run,"

I honestly don't think you will be disappointed once you drive it.

[This message has been edited by Oreif (edited 03-20-2008).]

The best test of HP to the wheel is again, the 1/4 mile MPH. Automatic transmissions and chassis dynos can do weird things. Take it to the track and get your MPH. Using your vehicle weight, you can get a much better approximation of your RWHP.

quote Originally posted by Oreif: Ryan, Do you happen to know if there was a gear difference between the power run and the 1/4 mile test? I don't know the ratio's of each gear in the transaxle, But from the huge difference between the 283whp shown on the 1/4 mile run and the 210whp I wonder if the readings were from different gears. It would be interesting to see what it does on a different dyno.

When we did the 1/4 mile simulation, we ran the car thru 1st, 2nd, and 3rd gears until the dyno reported we had traveled 1/4 mile. Supposidly the dyno loads the car down based on a factor the dyno operator puts in for wind resistance plus the race weight. I figured 3300 lbs with me in it (230lbs) which some on here have questioned but I figure 3070 lbs is going to be close to what this thing weighs with a full tank of fuel and no driver. The gearing of the 4T65-E is 2.93 overall final drive ratio, with 1st gear being 2.92, 2nd being 1.57, and 3rd being 1:1. I will tell you that we did get a little bit of wheelspin in 1st gear doing this 1/4 mile simulation.

Obviously tho, the 1/4 mile simulation and MAX HP / TQ numbers we got on the graph don't agree here. There's no way a 210whp 3300lb car is going to do 12.6 sec in the 1/4 mile. And like I said earlier, the dyno operator informed me that 210whp number is a "sustained HP reading which does not include peak power numbers"; whatever that means. This was the first time I had ever taken a car to a Mustang dyno so I'm not familiar with the setup. I've been on DynoJet dynos many times. The only reason why the decision was made to go to this dyno was because we got a "deal". Well it's beginning to look like that deal might have not been so great after all.

Just like doctors I think what we need is a second opinion here. Therefore I've already set up an appointment with the other dyno in town (Dynojet) for next wednesday that I am going to pay for out of my own pocket. I don't trust the numbers we got from this first dyno session because the data just doesn't add up correctly. I've run cars on this other dyno before and the numbers produced always seemed to be "in line" with what you see other people's cars doing on the net. I don't anticipate we are going to be disappointed a second time but we'll just have to wait and see what happens.

And I did want to add something... What has happened here is the very reason why I don't put too much stock into chassis dyno numbers. I think we've all established the fact that no two dynos are going to give you the same results. That's why I put more stock in 1/4 mile dragstrip runs. That's the number that really matters because it tells you what the car, as a whole, can do. Regardless of what this second dyno test reveals I think the true scope of what this car can do will only be realized once it hits the dragstrip. But nonetheless, I'm still curious to see how the DynoJet's numbers compare to what we saw yesterday.

-ryan

[This message has been edited by Darth Fiero (edited 03-20-2008).]

quote 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.

Obviously, I not know specifically what the dyno setup he was using while this car was on there, but when I ran the mustang dyno at my friends shop, we didnt have an option to do any correction factors after the fact, and 9 out of 10 times the correction factor was 100% (aka no correction), as it was roughly 65 degrees in the test lab, and nominal baro pressure. At times, you could watch the correction factor just change even mid run to like .99 or 1.01. My point to that is even IF it was outputting raw numbers the percentage it could be off kilter is very small, I honestly have never seen the a mustang dyno go more than a 1% correction. Now, to see a number you want to see (like 252 maybe?) you would need a 20% correction factor, that I feel is not possible with even the most extreme conditions. I have heard of dyno sessions in 100 degree sopping wet heat that produced at least close numbers, also been to the track on a few of those days and only seen my traps drop about 1MPH. And 90degree IAT readings are not uncommon within a closed area. We were reading temps close to 105-110 degrees F on a LS1 I dynoed on a outdoor dyno shop, on a windy day, with a giant fan blowing on it.

Again, I want to add I have no idea what those are actually based on, I am purely speculating here. I would be curious to see what the lambda was reading, and I dont think you actually posted a time that the simulated 1/4 mile sprint said (every 1/4 mile sprint I have done on a mustang was dang close to accurate).

quote Originally posted by darkhorizon: Obviously, I not know specifically what the dyno setup he was using while this car was on there, but when I ran the mustang dyno at my friends shop, we didnt have an option to do any correction factors after the fact, and 9 out of 10 times the correction factor was 100% (aka no correction), as it was roughly 65 degrees in the test lab, and nominal baro pressure. At times, you could watch the correction factor just change even mid run to like .99 or 1.01. My point to that is even IF it was outputting raw numbers the percentage it could be off kilter is very small, I honestly have never seen the a mustang dyno go more than a 1% correction. Now, to see a number you want to see (like 252 maybe?) you would need a 20% correction factor, that I feel is not possible with even the most extreme conditions. I have heard of dyno sessions in 100 degree sopping wet heat that produced at least close numbers, also been to the track on a few of those days and only seen my traps drop about 1MPH. And 90degree IAT readings are not uncommon within a closed area. We were reading temps close to 105-110 degrees F on a LS1 I dynoed on a outdoor dyno shop, on a windy day, with a giant fan blowing on it. Again, I want to add I have no idea what those are actually based on, I am purely speculating here. I would be curious to see what the lambda was reading, and I dont think you actually posted a time that the simulated 1/4 mile sprint said (every 1/4 mile sprint I have done on a mustang was dang close to accurate).

Explain to us then how this mustang dyno produced a 12.6 sec 1/4 mile run with what you say must be an accurate 210 whp reading? Those numbers just don't sound like they are correct to me. Back when my Turbocharged 3800 Fiero was running 12.6's, it dynoed 277whp and 395wtq on a dynojet.

blkcofy: A big "+" for you.

Finally a thread about performance that looks like it's not going to turn into a major flame war.

Finally there's an outlet where the people that want to police the power claims of others can come to keep other threads from turning into battle grounds.

IMHO, this thread can save 2 or 3 otherwise good threads a month from going down in flames.

If used properly, the Forum police, when they see what they think are incorrect claims, can simply say "When you get a chance to Dyno or run down the 1/4 mile with this car please post your results to the "XYZ thread"" (<~~~ including a link to this thread). And at that point, since they've made their mark, they can leave that thread alone.

Everyone has seen many good threads go down in flames when a gang of the forum police run to a thread just to gang up demanding proof of numbers posted. Many people don't even post anymore because they don't want to be subject to a bunch of demands of a few people.

Some people think they need to demand proof of everything, others are satisfied with what they have. This thread provides an outlet where we can finally have peace in all threads.

How come nobody ever was able to start a thread like this before?

If I could give you 10 "+"'s I would.

My suggestion to people who think they need to police the Forum for an accuracy, that others don't need, can save a lot of threads from going down in flames by simply saying "When you get a chance to Dyno or run down the 1/4 mile with this car please post your results to the "XYZ thread" we'd love to see the results" (<~~~ including a link to this thread).

Kudu's to u

Archie

[This message has been edited by Archie (edited 03-20-2008).]

Ryan, I'm curious what your reasoning was behind taking this car to the dyno? Was it to verify the new LS4 swap performed properly in a fiero, or do you dyno all your customers cars?

I think it was a customer request to have it run on a dyno.

I can't believe Lloyde's been able to stay away from this thread so far.

That said, there must've been something wrong with the load cell.

Did you do any data logging while you were on the dyno? As long as it was bringing the timing off base and you weren't blowing black smoke out the exhaust, I'd bet you made a lot more than what was indicated.

quote Originally posted by Darth Fiero: Explain to us then how this mustang dyno produced a 12.6 sec 1/4 mile run with what you say must be an accurate 210 whp reading? Those numbers just don't sound like they are correct to me. Back when my Turbocharged 3800 Fiero was running 12.6's, it dynoed 277whp and 395wtq on a dynojet.

I posted without knowing what the result of that 1/4 run was, I seemed to have missed it.

All I can say to that is I dont know. Something about that 1/4 mile run does not add up.... first you start off with a 2.0 60foot time, and then run a trap that is 2mph higher than my 12.8 run, and .3 faster, when I had a 1.8 60 foot... What I am getting at is the run itself looks marginally faster than mine, but the 60 foot is way out of line. I dont see any problems with that car pulling a 1.8 or even 1.7 60foot time, which honestly should cut about .4 or .5 off the final time...So that also is a bit missleading in the data department, to the tune of reading MUCH higher than it should.

Also, on a less important note, if the dyno WHP numbers were off, whats to say the 1/4 mile numbers were right on? I would agree with kurt that if the braking system in the dyno was off, it would give less load to the car than it should be, and also read low on the dyno WHP because it would not be braking hard enough to load the loadcell correctly. Example, if the brake was not working in any way, you would never measure even 1 horsepower, because the measurement taken from the amount of force the brake is applying to the motor, and not how much force the motor is applying the brake.

quote Originally posted by darkhorizon: All I can say to that is I dont know. Something about that 1/4 mile run does not add up.... first you start off with a 2.0 60foot time, and then run a trap that is 2mph higher than my 12.8 run, and .3 faster, when I had a 1.8 60 foot... What I am getting at is the run itself looks marginally faster than mine, but the 60 foot is way out of line. I dont see any problems with that car pulling a 1.8 or even 1.7 60foot time, which honestly should cut about .4 or .5 off the final time...So that also is a bit missleading in the data department, to the tune of reading MUCH higher than it should.

He said he had wheelspin in first while doing the 1/4 simulation, that would account for the 2.0 60 foot. The ET/MPH correlation are never the same between cars either. My friends 84 corvette on propane did the 1/4 at mid to high 13 but it crossed the line at 114 mph. Our local drag strip is only 384' long and his corvette will run the track in 6.0 at 79 mph with no wheelspin. My other friends mustang will do the same track in 5.8 at 65 mph.

Well I went to the Dyno finally last month after getting an engine together that wont blow up. Although it ate the trans right away, I'm pretty sure I got that remedied too.

We've still got major tuning issues with transmission control, hitting the cieling of the MAF in the PCM and a few other issues with the PCM. But my Dyno tuner is more of an all around type of tuner, and not near as proficient (sp?) with modified 3800 PCM's. Hopefully Brian @ Intense can help him along with the details & can solve all the problems.

I robbed the video from "Justa6" on youtube when the whole Minnesota group went. "MinngreenGT" has a similar one.

372 rwhp

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MINNESOTA MAFIA Real men get blown
87 GT MP-112 powered, 3800 Supercharged on 19's____88 GT T-top 1 of very few, 119.4 miles
87 GT custom______90 Grand prix STE Turbo_____98 ZX750R
IF YOU AIN'T BREAKING STUFF..................IT AIN'T MODDED ENOUGH
If your'e not living on the edge..........you're taking up too much room.
Best Fiero mounts available

[This message has been edited by PURPLE REIGN (edited 03-22-2008).]

quote Originally posted by crzyone: Great attitude. You can learn a lot about your engine and setup by a simple visit the dyno. If you learned something then it was worth it. The new mandrel bent exhaust should help you out a lot. Big cubes pushes big air, good to get rid of any restrictions in flow. What are you running for exhaust manifolds?

My exhasut manifolds are Brzezinski modified 2.5" ramhorns, basically they open up the outer ports for better flow, I heard so many issues with sandersons cracking etc that I wanted to stay with something more robust, plus these came up on ebay for a good price.

quote Originally posted by Zac88GT: He said he had wheelspin in first while doing the 1/4 simulation, that would account for the 2.0 60 foot. The ET/MPH correlation are never the same between cars either. My friends 84 corvette on propane did the 1/4 at mid to high 13 but it crossed the line at 114 mph. Our local drag strip is only 384' long and his corvette will run the track in 6.0 at 79 mph with no wheelspin. My other friends mustang will do the same track in 5.8 at 65 mph.

I know why he got a 2.0 60, but I know that he would be running alot faster if he got a real 60, that really makes that 12.6 VERY suspisious. If you corrected that time with a 1.8 60', I would go to guess he would be running a 12.2, a full .7 faster than the 3800 swaps with 260whp.

I am still standing by my conjecture of a failed dyno brake, it would show extra fast 1/4 times, and extra low horsepower.

Please everyone take this into consideration.
We are talking about 7000 RPMs or more on some engines.
Your back is to a Clutch or Torque Converter and a Gear Box or a Box of Gears!
Boom.
Please cover the Trans or the Firewall. This will help with heat also. NHRA has some guide line for cars.

[This message has been edited by AJxtcman (edited 03-20-2008).]

That is really on my mind with having a modified flywheel right behind my back. I think upgrading to a Spec aluminum flywheel will be a smart move for me.

I don't dyno every swap I do. I only dyno those that the customer request be dynoed and pays for it to be done.

I've never dynoed at this shop before and probably never will again, based on the lack of information I was getting from the dyno operator. The only reason why we took this car to this dyno was because we were offered a "deal" for at least 3 pulls @ $50. The other dyno shop that I am taking the car to next week charges $85 for 3 runs. Just to be clear it was not my decision to take this car to the mustang dyno, it was the owner's. Having said that, neither I nor the owner had any idea that we were going to run into these issues and get conflicting dyno results.

As stated before in this thread, there was some wheelspin during initial take-off during the 1/4 mile simulation which probably resulted in the 2.0 sec 60' time. But I've seen a lot of cars cut a 2.0 sec 60' time and still run 12's or faster in the 1/4 mile, just because of traction issues. So just because car "A" can run a 12.2 sec in the 1/4 mile with a 1.8 sec 60' time doesn't mean car "B" can't go faster with a slower 60' time. It all boils down to the amount of power the engine is making and how well the engine can sustain that power throughout the RPM band. One thing you can see from the HP/TQ graph is how flat the power band for this engine is.

-ryan

Blkcofy, Darth Fiero:

I was thinking about this whole concept of "sustained horsepower". I think that we should be able to apply some physics to see if we can come up with what it may mean.

My DD is a ~4000 lb (1818kg) with driver GP GXP with the same drivetrain you've installed in Blkcofy's vehicle. Yesterday I logged a 0-60 run using HPT. This was a frosty, foggy morning, traction was really limited.

0-60 time = 5.715 seconds, which is bang on the advertised speed, but with massive wheel spin. Here's a chart of the "wheel speed" and throttle position versus time on the first gear portion of that run:



So what does physics tell us about the "sustained power" delivered to the road?

Time in first gear (t) = 4.585 sec, speed at shift 83kmh
Acceleration (a) = dV/dT for first gear this translates into an average of 5.028m/s^2
Force (F) = m*a = 1818*5.028 = 9.141.77 kg*m/s^2 (Newtons)
Distance Traveled (S) - 1.2*a*t^2 = 52.85m
Work done (W) = F*S = 483,187 Nm, or Joules
Power (P) = W/t = 483,187/4.585 = 105,384 Joules/sec or Watts
HP = kW/.735 = 105.384/.735 = 143.38 hp

So what happened to the 303 crank hp? Some is lost in the drivetrain, some went into melting frost and heating/smoking tires, the rest got averaged out.

Don't sweat a 200 hp sustained power number from a dyno that was having reporting problems!

[This message has been edited by TiredGXP (edited 03-22-2008).]

That dyno graph was taken in second or third gear.... Wheel spin was NOT a factor, so there is no comparison with what your trying to get at with a low dyno number.....

It sounds like the HP is an avrage but not a peak HP due to you are changing gears in a 1/4 mile run if they where doing a peak Hp run you would put it in one gear and run it through the rpm range

quote Originally posted by darkhorizon: That dyno graph was taken in second or third gear.... Wheel spin was NOT a factor, so there is no comparison with what your trying to get at with a low dyno number.....

But if you were to look at any section of the data, whether there is wheel spin on NOT, the same relationship holds true. It doesn't matter what gear you are in, the math describes the actual road acceleration of a mass. Over the last 20 frames of the scan used in the earlier post there was no wheel spin. The "sustained power" for those frames was calculated as 191 hp using the same formulas as above. If you apply the physics on a frame by frame basis, "instantaneous" HP value was as high as 239, only one frame was less than the calculated "sustained power" value. I'm pointing out the math that demonstrates a calculation of "sustained power" significantly understimates the actual power delivered at a point in time.

Anyone with a scan tool can reproduce the results. If you don't like it, argue about it with Sir Isaac Newton.

By sustained power they might be refering to something like the total area under the curve over a certain rpm range, then divided by the rpm range limits to give an equivelant average horsepower.

Maybe I should change the name of the link

quote Originally posted by PURPLE REIGN: Maybe I should change the name of the link

Or maybe we'll quit hijacking the thread, because it really was a good idea!

quote Originally posted by Zac88GT: By sustained power they might be refering to something like the total area under the curve over a certain rpm range, then divided by the rpm range limits to give an equivelant average horsepower.

I also think something is up. Sustained power is much different than peak HP. I think the number readout on the 1/4 Mi test is more along the lines of what we're looking for. I think most everybody agrees that GM's claims of 303HP are likely to be accurate (maybe even underrated), and the workmanship here is well proven, and well respected.

I have a question on this topic.

I dyno'd a stock 2003 Cadillac DHS along with my Fiero. The DHS had a hot tune in it. The best we got out of it was just under 200 WHP.

If I change the torque multipler and rerun it on that very nice Dyno Dynamics dyno will the numbers go up?

Most 2000 to 2003 Northstars put down a number around 225 WHP. The operator of the Dyno told us that the numbers would be off by 13% from a DynoJet. 200 + 13% = 226

If I change the torque multipler will it make a greater difference in the results if it is on a eddy current or a centrifugal dyno?

quote Originally posted by AJxtcman: I have a question on this topic. I dyno'd a stock 2003 Cadillac DHS along with my Fiero. The DHS had a hot tune in it. The best we got out of it was just under 200 WHP. If I change the torque multipler and rerun it on that very nice Dyno Dynamics dyno will the numbers go up? Most 2000 to 2003 Northstars put down a number around 225 WHP. The operator of the Dyno told us that the numbers would be off by 13% from a DynoJet. 200 + 13% = 226 If I change the torque multipler will it make a greater difference in the results if it is on a eddy current or a centrifugal dyno?

I kind of know the dyno operater, I drill with hin in reserves. He told me about the dyno, He also said that their dyno is lower than most dynojets. He did say his BMW dynoed 240whp with light mods, Sorry i did add anything helpfull, but I imagine similar results could be seen on both types of dynos. Im under the impression an eddy current is more sensitive to changes in moment.

quote Originally posted by TiredGXP: Or maybe we'll quit hijacking the thread, because it really was a good idea!

Went to the other dyno shop in town today to get a "second opinion" on the power this car is making...







We executed 3 pulls:



As you can see from the results above, all three pulls were pretty consistant. I had them remove two of the pulls from the graph and just print out the best (HP) one:



Max WHP: 271.20
Max WTQ: 277.07

You can see on the dyno charts that the weather conditions were better than SAE ideal, thus the correction factor was less than 100% (meaning the engine was actually putting down more power to the dyno than these SAE corrected graphs show). Also you can see the AFR's didn't look bad at all (dashed line on the AFR graph represents 13.0:1). The beginning of the dyno pull did start out a little lean because they were easing into the throttle; but by about 4500rpm, the AFR's were near-perfect for what I wanted to see.

TiredGXP mentioned earlier in this thread that people taking their stock LS4-powered Grand Prix GXP's to the dyno were getting anywhere from 230whp (a 24% loss thru the drivetrain) to 252whp (a 17% loss thru the drivetrain). If you apply the same loss % factor to the dyno runs I did today, then we can figure blkcofy's engine is producing:

317.3 ~ 336.3 @crank hp
324.2 ~ 343.6 @crank tq

Assuming a 24% drivetrain loss, that means the mods done to this engine have gained about 33hp and 20tq at the crank. Of course there's no way to measure the actual loss thru blkcofy's drivetrain unless we pull the engine and put it on a dyno by itself. Also we have to assume the dyno numbers I got today aren't going to exactly match the dyno numbers other people are getting.

Hopefully today's dyno test puts blkcofy's mind at ease. I knew the mustang dyno's conflicting dyno / simulated 1/4 mile sprint test just didn't sound right. I think today's results prove that point.

-ryan

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power corrupts. absolute power corrupts absolutely.

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quote Originally posted by Darth Fiero: TiredGXP mentioned earlier in this thread that people taking their stock LS4-powered Grand Prix GXP's to the dyno were getting anywhere from 230whp (a 24% loss thru the drivetrain) to 252whp (a 17% loss thru the drivetrain). If you apply the same loss % factor to the dyno runs I did today, then we can figure blkcofy's engine is producing: 317.3 ~ 336.3 @crank hp 324.2 ~ 343.6 @crank tq Assuming a 24% drivetrain loss, that means the mods done to this engine have gained about 33hp and 20tq at the crank. Of course there's no way to measure the actual loss thru blkcofy's drivetrain unless we pull the engine and put it on a dyno by itself. Also we have to assume the dyno numbers I got today aren't going to exactly match the dyno numbers other people are getting.

Muuch better. I think a 4t65e is going to run you about a 21% loss. 25% is closer to what the 4t80e losses are. BTW, apparently they can do a "negative HP dyno" to find the drivetrain losses. Basically running the car up to speed in a certain gear and then disconnecting the engine and measuring the torque taken from the dynamometer to spin the drivetrain. Haven't done it, but it's on my to-do list. I think it's only available with dynojets.

Excellent post.

Glad to see it's making what was expected.

For those of you who are interested, I did take a scan log during all 3 dyno pulls and saved that log to a .csv file you can look at here:

dynotech.csv

[This message has been edited by Darth Fiero (edited 03-26-2008).]

Sounds about right, I am sure the exhaust and intake work is all that it needed to get the 270's. There is obviously somthing wrong with the mustang dyno, because it should have read about 250 even on the mustang, if it was putting down mid 270 on the dynojet (I have done a few direct comparisons and it comes out to what everyone says it is).


[arrogant racing talk]
I still highly doubt that your 1/4 mile time on the mustang was even close to right. My 12.8 second car makes high 250's on my friends mustang dyno, and I have a ton of powerband advantages over the LS4. Lets see a real time out of that beast this year! The michigan group up here is going to milan in july for the 25th, its not far from ohio (I think toledo is closer than me)[/arrogant racing talk]

Darth, This is a much more reasonable result, very close to expectation.

I took a look through the log file. Looks like this engine is flowing about 10-12% more than stock in the upper RPM range (based on dynamic cylinder air numbers), which definitely helped retain torque and power above 5,600RPM. The porting job definitely paid off.


If you're up for a bit of unsolicited comments on the log, here goes: A little bit of KR is showing up, so it might not hurt to back the WOT timing off a degree or so. Commanded AFR in PE seems a bit lean @ 13.5, it wouldn't hurt to richen it up to 12.8 ~ 13 (although the WB shows ~13, if it was in the tailpipe after the cat the reading could be out a few tenths).

Cheers

[This message has been edited by TiredGXP (edited 03-26-2008).]