quote Originally posted by Joseph Upson: The VVT on the 3900 likely doesn't offer as much for the torque range as one would like to think, simply because of fixed cam lobe separation in this app, myself and Joshua have already proven what was speculated in advance elsewhere, that the 3900 cam has more advance and retard range than what is useful. That's why I mentioned the benefits it offers towards emissions, it is the reason the EGR valve could be eliminated. Dual cam VVT is where the most significant benefit is such as in the 3.6L which has a non direct injected 270 hp version.

I looked all over the GM powertrain website and I was unable to find a 3.6 DOHC VVT NON-DI engine that made 270hp stock. What year/make/model of vehicle did the 270hp version you cite come in?

The EGR valve has been able to be eliminated on engines that don't have VVT. The first versions of the 3800 TPI L27 vin L's didn't have EGR. The 3300 V6 didn't have EGR. And a lot of the LS truck engines didn't have EGR. The EGR valve is only needed when combustion pressures and temperatures are high enough that excessive NOx gases are produced under "normal" engine loads. Using a cam with enough overlap can eliminate the need for an EGR system. So saying one of the primary reasons the VVT system was put on the engine was to help with emissions porbably isn't accurate (although I'm sure it helps).

quote The VVT 3500 produces 16hp more than the non VVT 3500, is that because of the VVT, or the 3900 heads and intake system it has over the non VVT motor. I'm sure it's a combination of both. Torque is very important but you still need a sufficient amount of hp also otherwise we'd be loosing to diesels.

You guys need to get off your HP kick. HP does you no good accelerating off the line. If it did, we'd all be losing to 4cyl rice burners in drag races that make twice as much HP than they do TQ. The Fiero doesn't weigh 2000lbs, it weighs significantly more and we do need torque to get it moving off the line. It can be said that when you look at a 1/4 mile timeslip, the MPH at the traps is a good indicator of how much HP your engine is making but TQ is what gets you there in the amount of time that is indicated in the E.T. And last time I checked, he who runs the fastest E.T. is the one who wins (assuming equal reaction times).

I'm surpised you brought up the diesel arguement seeing as how diesels are usually done making power by 3000 or so RPM. Sure, they make outstanding torque from idle to 3000 or so RPM, but that doesn't give you a lot of power band / RPM range to play with, especially when you are comparing them to engines that can produce relatively flat torque curves for about double that amount of RPM.

quote I've mentioned it before but here it goes again, WOT-Tech on the 60 degree forum offers performance parts for these engines, mainly the 3500 and below at this point. CNCguy also on that forum offers parts to........I purchased a new Northstar throttlebody (other choices available) and adaptor plate, had a 7x trigger ring made and had the stock camshaft reground. The 3 required parts for the swap cost me ~$150, the camshaft regrind was optional but cost ~$85. I decided to make headers, flanges $50. That's it aside from the 730 ecm swap. I've had tuning software and hardware since the forum was new. I forgot about the bypass pressure regulator to convert to a returnless fuel system, depends on your approach, $100 for me, and a must on the 3900, you can use the 3400 rail on the 3500.

So we've got 1, maybe 2 sources for aftermarket parts; and most aren't made specifically for the 3900? Doesn't sound like there are a whole lot of choices there. The prices you list look cheap enough but I have to question a few things like: Is everyone going to be able to get the same cheap prices as you did? What have you left out (hidden costs such as gaskets, labor to tear down and reassemble the engine, etc)? And the all-important: how much gain in HP/TQ will we be seeing with each upgrade you cite? Are we talking about a 20hp gain for a $150 mod or what here?

Beyond that and most importantly, I have to ask this question: Say someone starts out with a stock VVT engine and removes VVT so they can run an earlier ECM (such as the 7730); how many mods/upgrades (and what is it going to cost them) to get the engine back to performing the way it did stock (with the VVT) when we are talking about 1/4 mile ET performance? I have no doubt you guys can increase the PEAK power one of these engines produces with a few mods after removing the VVT system, but peak HP gains don't easily translate into better acceleration performance. I do have doubts you can make the engine produce the same flat torque curve as it did stock with the VVT system functioning after you remove it, regardless of what cam you use.

quote Tuning is part of the swap with any modified engine even if you swap the OE PCM with it so lets not beat that "horse". The potential to make excellent power without spending the kind of money non aluminum head engine owners seem to be aledging is there. The power to weight ratio for the engine is an advantage in itself, the aluminum heads weigh right at half of what the iron 2.8L heads do and I imagine there's an even greater over all weight savings relative to the 3800.

The stock 2.8 iron heads weigh what, 25lbs each or so? So even if you half that, between a set of two heads changing from iron to aluminum you're only saving 25lbs or so on the engine... Doesn't seem that significant to me. Yes, there is no doubt that the 3800 is a heavy engine, but when we are talking about total engine weights, how much difference are we really talking about here? 100-150 lbs? That probably isn't worth a tenth in the 1/4 mile (of course it is more significant when we are talking about road racing so I'll give you that).

quote You can swap the 3500 with a PCM used to control the 3400. The 3500 top end is a popular upgrade for the 3400. It all just boils down to the trend of "doing what you know" on this forum, otherwise from a number stand point the naturally aspirated aluminum head motors are a better choice for performance. Less weight and more power per litre in the conservative ranges many operate in here. VVT is a treat, not a necessity, loosing it doesn't suddenly make an engine a slug. It also doesn't severely reduce its power, just the versatility of it like in the 3800, it becomes a happy medium.

VVT may not be a necessity, but it does significantly impact the power curve on the engines it comes on, and I still don't think getting rid of it helps you at all.

You're right: It does boil down to "doing what you know". And as much as I didn't like the "warm welcome" us 3800 guys received back when the 3800 SC was first being discussed as a swap candidate for the Fiero; we still had to deal with it. As more swaps were done and it proved itself as an outstanding performer, the 3800 earned respect in this community and others. You 3500/3900 guys are going to have to deal with the same, and the 3500/3900 swaps are going to have to PROVE their worth whether you like it or not. Bottom line: I don't see 3500/3900's in swaps or cars they came in from the factory running impressive track times anywhere near what that the 3800's have been able to do and are currently doing. One day that might all change.

But for now, if you're looking for respect for your engine of choice; it is going to have to EARN IT.

-ryan

[This message has been edited by Darth Fiero (edited 02-08-2011).]

Hey that's entirely too much writing. There is someone making 238 hp and lb/ft at the wheels with a 3900 using a traditional non VVT camshaft. Regardless, without VVT it works the same way the 3800 does not worse. Still with or without respect, it's more power per litre and cam in block VVT does not measure up to independent intake and exhaust valve VVT by a long shot. The 3900s days are numbered too partly because of that.

quote Originally posted by Joseph Upson: Hey that's entirely too much writing. There is someone making 238 hp and lb/ft at the wheels with a 3900 using a traditional non VVT camshaft.

That's great, but how does it perform in the 1/4 mile and how does that compare to a stock engine with a functioning VVT system in the same vehicle?

quote Originally posted by Darth Fiero: That's great, but how does it perform in the 1/4 mile and how does that compare to a stock engine with a functioning VVT system in the same vehicle?

You're giving VVT too much credit in this case Darth, the 3900 has an LSA of ~117 degrees. In accordance with camshaft dynamics, wide LSA= broad torque band. That's another reason I say VVT in this engine isn't that big of a deal and has as much or more to do with emissions.

Good dialogue though.

quote Originally posted by Joseph Upson: It's good dialogue and there's reasonable opposition or doubt as the newer motors still have to earn their keep. I looked at the specs for the 04 GTP, 06 GXP V8 and 06 G6 GTP coup, the G6 is faster than the GTP in the quarter convincingly if the data is dependable, yet both cars weight within 100 lbs of eachother, G6 14.2 vs. GTP 14.9s, the GXP, 14.1s but it's about 200 lbs heavier.

A G6 weighs within 100lbs of a GTP? Where did you get this information?

quote Originally posted by Darth Fiero: And I think you're not giving VVT enough credit. So until you can show me some side-by-side drag racing comparisons that prove your point, I'm not going to be convinced, sorry.

That's documented fact from camshaft manufacturing and testing as to the effects of broad and narrow LSA. You don't need a drag race for that.

quote Originally posted by Joseph Upson: That's documented fact from camshaft manufacturing and testing as to the effects of broad and narrow LSA. You don't need a drag race for that.

I'm not talking about LSA. We were talking about the difference of having VVT and not; at least that's what I thought we were talking about in most of our discussions between you and I in this thread...

But since you brought up LSA, I would generally agree with your statement. A cam with a wider LSA is going to produce not only a broader torque band, but it will do so generally at lower RPM and will also produce a more stable (and smoother) idle. The only problem you get with a wider LSA is combustion pressure increases too at certain operating ranges and this can be a limit of how much compression ratio you can run for a given fuel octane.

[This message has been edited by Darth Fiero (edited 02-08-2011).]

quote Originally posted by Darth Fiero: I'm not talking about LSA. We were talking about the difference of having VVT and not; at least that's what I thought we were talking about in most of our discussions between you and I in this thread... But since you brought up LSA, I would generally agree with your statement. A cam with a wider LSA is going to produce not only a broader torque band, but it will do so generally at lower RPM and will also produce a more stable (and smoother) idle. The only problem you get with a wider LSA is combustion pressure increases too at certain operating ranges and this can be a limit of how much compression ratio you can run for a given fuel octane.

Yes, that's why I pointed out the effects of the wide LSA on the VVT engine, the LSA alone promotes a broad flat torque curve without VVT. In case of the 3900, it's a simple traditional camshaft with the ability to retard or advance without disassembling the engine.

You and I both know that with a fixed lobe camshaft you tend to get better low end torque when advanced, literature does not guarantee the same for retarding it. The effects are also limited to small increments. The 3900 has far more movement than can benefit power and torque. Some of the advance is also to benefit idle as GM has documented.

So let the 3800 go for the 3900, GM did. I have a nice engine available for a good price when you're ready. Just kidding with you, I may need some more help with that digital cruise install so I need to stay on your good side.

quote Originally posted by Joseph Upson: So let the 3800 go for the 3900, GM did. I have a nice engine available for a good price when you're ready. Just kidding with you, I may need some more help with that digital cruise install so I need to stay on your good side.

You never got on my bad side so no worries. I'm glad we've been able to keep our discussion going, there's a lot of good information in this thread.

As far as letting the 3800 go for the 3900; GM let the 3.8L Buick Turbo engine go after 1989 but today there's more support for it than there ever has been for the 3800 (thanks mainly due to the huge following it has in the Turbo Buick GN community). Recently a few of us 3800 guys have been able to turn some GN owners on to the 3800 and get them to open up to using a 3800 with a turbo in their cars. So based in what I see over there, I would say the 3800 is going to be around for a long time.

That is as long as gas prices don't get out of control... If they do, we can ALL kiss our hobby of modifying gasoline engines goodbye.

-ryan

quote Originally posted by Darth Fiero: As far as letting the 3800 go for the 3900; GM let the 3.8L Buick Turbo engine go after 1989 but today there's more support for it than there ever has been for the 3800 (thanks mainly due to the huge following it has in the Turbo Buick GN community).

Heh... that and the fact that the old 3.8 blocks blow up at power levels that 3800's can take with stock internals, necessitating the need for things like TA's aluminum V6 block.

quote Originally posted by Joseph Upson: Hey that's entirely too much writing. There is someone making 238 hp and lb/ft at the wheels with a 3900 using a traditional non VVT camshaft. Regardless, without VVT it works the same way the 3800 does not worse. Still with or without respect, it's more power per litre and cam in block VVT does not measure up to independent intake and exhaust valve VVT by a long shot. The 3900s days are numbered too partly because of that.

I know one guy that made 249 ft*lbs with a 3400 block and a Fiero intak and heads. :-)

isn't the 3800 an iron block with aluminum heads and the 3900 an aluminum block and heads? I think that makes for a more substantial weight difference, also, since the block is 60 degrees instead of 90, you remove alot of material from in-between the banks.

also, maybe it's just my bad luck, but every 100K+ mile 3800 I've messed with leaks oil faster than you can pour it in.

quote Originally posted by ericjon262: isn't the 3800 an iron block with aluminum heads and the 3900 an aluminum block and heads? I think that makes for a more substantial weight difference, also, since the block is 60 degrees instead of 90, you remove alot of material from in-between the banks. also, maybe it's just my bad luck, but every 100K+ mile 3800 I've messed with leaks oil faster than you can pour it in.

No, the 3800's always had iron blocks and iron heads. Yes there are some nagging oil leakage issues with the 3800's but those can be fixed by using revised gaskets and sealing procedures.

3500 and 3900 were both pushrod engines that had iron blocks and aluminum heads.

3.6 DOHC VVT had an aluminum block and aluminum heads.

-ryan

quote Originally posted by Darth Fiero: No, the 3800's always had iron blocks and iron heads. Yes there are some nagging oil leakage issues with the 3800's but those can be fixed by using revised gaskets and sealing procedures. 3500 and 3900 were both pushrod engines that had iron blocks and aluminum heads. 3.6 DOHC VVT had an aluminum block and aluminum heads. -ryan

I do have to agree about the vvt in the 3.9 probably not being worth as much for the torque curve, as it's made out to be, but it's tough to say, because most without vvt aren't stock at all. a better look into the vvt issue might be to compare the LX9(non vvt 3500) and LZ4(vvt 3500) torque curves. I'm not sure how similar the cams and intakes are between the two though.

It's all a little moot really. I know the engine will not run with the cam fully retarded. I also know peak power comes on way before the advertised 6,000rpm with the cam fully advanced. so something needs to be done. I would like to see the popularity of the engine pick up and we have one example of a turbo application, mine with custom cam and now we need someone else to step up using a stock G6 PCM. Joseph, can you post my dyno graph here? I'm slightly disappointed but not embarassed, I was hoping for closer to 260whp.

I agree also about wanting to see more swaps done using these engines. More choices available for Fiero engine swaps sure won't hurt!

quote Originally posted by joshua riedl: It's all a little moot really. I know the engine will not run with the cam fully retarded. I also know peak power comes on way before the advertised 6,000rpm with the cam fully advanced. so something needs to be done. I would like to see the popularity of the engine pick up and we have one example of a turbo application, mine with custom cam and now we need someone else to step up using a stock G6 PCM. Joseph, can you post my dyno graph here? I'm slightly disappointed but not embarassed, I was hoping for closer to 260whp.

As I mentioned in the PM, I believe your engine has more cam than it needs and that there's more tuning to do.

[This message has been edited by Joseph Upson (edited 02-08-2011).]

I am doing one right now. Search for UND_Sioux Formula Build Thread.

I got a 3.9/4T65E with 26 miles on it with the computers and harness for $1300 delivered. The engine was out of an Uplander.

I pulled the entire electrical system from a 2006 Monte and will be incorporating the BCM, electronic throttle, etc... into the Fiero.

Nice, with the same transmission we'll have a good comparison.

http://www.g6ownersclub.com...showthread.php?t=750
Here's a link to a stock 3900 dyno. It's obviously cartoonish but it does appear I'm lacking torque without VVT
http://60degreev6.com/forum....php/38050-3900-Dyno
another aparently stock motor.

[This message has been edited by joshua riedl (edited 02-08-2011).]

quote Originally posted by joshua riedl: http://www.g6ownersclub.com...showthread.php?t=750 Here's a link to a stock 3900 dyno. It's obviously cartoonish but it does appear I'm lacking torque without VVT http://60degreev6.com/forum....php/38050-3900-Dyno another aparently stock motor.

You have to account for torque loss due to your camshaft. When you increase duration above stock with all else the same like compression for instance, bottom end torque loss is a given and guarantee. You gave up the wide LSA the stock cam has which makes for a more peaky narrow torque curve.

That first plot is from GMs website.

[This message has been edited by Joseph Upson (edited 02-08-2011).]

Look at the illustrations and note the effect of the combinations Joshua, high lift + short duration produced more power than moderate lift and long duration, you have long duration and high lift combined so your low end performance should be reduced.

http://www.popularhotroddin...ft_basics/index.html



Here note the difference in torque between the lowest and highest duration cam, it is very significant on the low end, and top end. Your camshaft has extreme lift and duration relative to the stock camshaft so it stands to reason that the camshaft grind is the cause of a large amount of your bottom end power loss, also keep in mind that the flow dynamics of the 3900 may not be complimented very well by your camshaft selection overall. Since the heads were patterened after the LS1 heads and it has the same cylinder bore diameter perhaps a cam more characteristic of what works well in the LS1 would make the best choice for it.



I also believe there's still more locked up in your tune due to having started with the 3.4 DOHC tune as we've already discussed. Since this engine has piston oil squirters perhaps you can bump your wideopen throttle AFR ratio up a little if it's at 12.5:1 or lower.

[This message has been edited by Joseph Upson (edited 02-09-2011).]

According to the graph my low end power is greatly increased. The only catch is neither one of us has a stock cam or vvt so I don't know where I stand compared to a stock 3900. http://www.g6performance.co.../showthread.php?t=34 Here is a 3900 quarter mile list and the closest thing to me has nitrous in a heavier car. It seems I'm doing pretty well power wise but it's never enough. I'll hopefully do better at the track this year since I shouldn't have any knock retard and Darth did go over the tune. This was all done after the graph posted. I'll get another dyno after the weather warms up a little.

Here is my GTech run before the twin turbos were removed and the engine stroked. The camshaft was advanced ~15 deg, the tune was still rough and it was only a second gear pull, not sure if 3rd would have made a big difference. That was with 7 psi also. After correcting the weight in the GTech it came out to about 215 hp and 267 lb/ft at the wheels. As you can see the excessive advance peaked everything out by 4400 rpm. Can't wait to see what proper cam install, additional compression and stroke and more importantly proper tuning produces from the new engine.

It's definately quicker now with boost turned off than the previous arrangement was with it. I researched the GTech rr before buying it and it proved very close to actual compared to dyno and track times, certainly far more accurate than Desktop Dyno. Hope to have dyno and track data before summer.

[This message has been edited by Joseph Upson (edited 02-09-2011).]

quote Originally posted by Darth Fiero:The common non-direct injected 3.6 DOHC VVT engines produce about 250hp and 250tq. I wouldn't say that puts a 3800 SC to shame. The direct injected version produces 304hp and 273tq which is impressive, but there's a problem. There is NO aftermarket tuning support currently available for the ECMs that control this engine, at least none that I am aware of. Without it, you can forget about swapping one of these engines into a Fiero unless you are prepared to swap a whole lot of other electronics from the donor car in when you do the swap. This isn't going to make the swap easy (or cheap if you are paying someone else to do it). I HOPE support for these systems does come out soon and I hope it can disable VATS (and/or the need to have the BCM or any other modules present for the engine to run right).

This company says they support the direct injected 3.6 DOHC VVT. They have been doing some tuning on the camaro. Not sure what they can and can't tune, I did piece together some of what they can do but none of it talks about VATS, though I thought I read somewhere they can disable it. I don't know, but I would like to know, if they can do what is needed so the engine can be swapped into a different car. It does help though that the camaro is using this engine, that should create some aftermarket parts.
http://trifectaperformance....pportedvehicles.aspx