3.9 Liter LZ8 specifications needed

[Beau]

Im working on a turbo kit, Im in the early EARLY phases of math design. I need to know some of the following.

Im trying to figure out if anyone can get the 3.9 LZ8's :
-Cam specs (full)
- Spark Advance
- Head flow CFM or Coefficents
- upper intake CFM or Coeffients

- Do we have any data on the exhaust? Primary lengths (average)
- Exhaust system CFM?

- Also at WOT do we have any idea at what RPM the Cam is degreed?

[Manitcor]

RE: 3.9 Liter LZ8 specifications needed

I dont think anyone has alot of info on that motor yet, it will be some time before someone gets the parts to tear into one. Main issue being that just about everything on the 3.9 and the 3.5 VVT engines are completly unusable on the earlier engines.

how are you planning on Tuning the PCM, AFAIK no one has a tuner capable of modifing the new GMLan based PCMs.

[Azrael]

It's even more diffcult since the cam uses a phasing system that can advance or retard intake and exhaust timing several degrees. The Upper intake is also a variable 2-stage design adjusting between longer runners for low rpm torque and shorter for high rpm HP.

[Beau]

Yep, all of the above information you guys has provided is true. Except the ability to negotiate with GMs new Controller Area Network it uses for electronics. Its a CAN system that GM doesnt call a CAN.

But by the time Im done with all of the logistics of it, and calculations tuning will be available.

So that leaves me with the remaining questions yet untouched.

Do we have any resources on the board that has access to GM material of this nature?

Edited: Computer = Controller, I was nearly sleeping when I wrote this. Sorry gang. Hehe there goes my credibility :}

[Hemet8]

A turbo 3900?? Looks like the land speed record is going to get challaged again.

[tejohnson]

There is Rumor that DHP will be supporting the CAN (Controller Area Network) protocol eventually. This will require a different interface cable tho. There are a few threads on GAGT where CAN is discussed:

ex: http://www.grandamgt.com/forum/showt...534#post709534

I'm sure it will be an interesting topic as time progresses and folks start getting/using newer GM cars, engines, trannies, etc.

[v6h.o.]

GM does call it a CAN system. Hence why we have CANdi modules to plug in series with the TECH2 scan tools to read and communicate with the new CAN systems.

There just isn't any of that information out available to the public. You would have to contact the engineers at GM for most of what your after right now.

[tejohnson]

If you look at the URL I posted, you can see I included some info in the posts on some classes you can take for GM's Single Wire CAN implementation... I would personnally like to attend one... Someone want to fund my field trip?

RE: http://www.gmtcny.com/lan.htm

http://www.vector-cantech.com/index.html?../training?classes.html

Should also point out it requires approval by GM. lol

[Beau]

Hrmm still looking for those specs, I can estimate safe timing advances for now, but I cannot fake Cam specs. The head flows for now im using the 3.8 Series II with a compensation for a .07 larger intake valve diameter to adjust for flow. Actually the exhaust side is the same. Which probably means GM wised up to the flow ratios that were way off, where the exhaust flowed nearly as much as the intake, in both stock and ported situations.

A good rule of thumb is exhaust flow = 80% of intake, well the L67s exhaust flowed something like 94-96% depending on the casting :} DOETH!

so for now I can even estimate head flow numbers, although I wish I didnt have to.

Right now im just trying to reverse engineer the motor, Im getting specific calcuations to match with thier engine dynos they provide on Gm powertrain, but the problem is I have to tweak certin things to get the correct drop offs and peak powers, and yes I know to phase the cam, but that doesnt seem to be the only factor.

Does GM provide engine dynoes with Full exhaust btw?

[Manitcor]

not that is published anywhere public, i did some research into the GMLan (CAN) from what I can tell it is actually a form of a token ring network similar to that used for PC networking in the mid 90s but much lower bandwidth. It seems to be loosely based on an old RFC spec. If I had the time im pretty sure i could sniff traffic on the CAN with a standard latptop and a modified token ring NIC. Unfortunatly I have neiter the time nor the materials todo it. DHP does though

If the 3900 follows true to form with the previous 660 egines you can easily turbo the beast with no moditifcation from stock with the exception of perhaps larger injectors and of course computer tuning.

How far you plan on going with the 3900? What car are you putting this proposed monster in?

[Beau]

Well, Im not sure how far I can take the 3900. There will be some speculation, I will tell you what the limiting factors will be.

The 60 GM v6s are NOTHING like the 90 degree ones IE the 3800 Series II, which I've come to love, and actually years ago a started a turbo revolution for the platform, and people with more resources than I have been able to come out with and build GPs with these turbo motors to present some VERY impressive times. In the 9s actually. Not bad for FWD.

I'm concerned with working on a 60 degree GM motor. Guys please do not take this the wrong way, I respect the knowledge thats evident with many board memebers here but... The 60 degree motors are near.. well crap.

They aren't very strong (awesome for what GM meant them to do btw), they make some of the most dismal numbers out there for.. well anything, not just displacment. Terrible head flow characteristics. etc etc.

So Im honestly afriad the 3900 shares too many things with the 3.4(3400) liter motor, which is honestly garbage. Which means the 3.1 is Garbage.

Although the 3100 (not the 3.1) took forever to die even when driven hard, but thats what happens when you make no horse.


Why I think the platform might work:
- I've been told the 3900 had a forged crank (not sure the process but Id assume to be sinter forged) , heard the rods were sinter forged. The pistons as true to GM im sure are silica garbage. (which is fine). So Im optimistic about the bottom end, good start.

- 3.9 liters of discplacment

- VVT (tuneability)

- Easy to mod IE cam, pushrods.

- Aluminum heads

- Piston Oil Squirters (this is actually a big deal)

- Sopposed new combustion chamber designed, designed off off LS2 and LS7 wedge designs.

- The fact that peak horse is at 6k rpm, which is very important, it shows me that Volumetric effiency isn't as poor as on the 3.8 SII (although this could be from high lift, and JUST the VVT of course, but Im hoping it has to do with higher head flow numbers)

Here is why Im skeptical of the motor.
- Dont know what cam specs they used to get the horse numbers they've got

- The 60 degree Aluminum heads traditionally flowed like GARBAGE both stock and ported.

- Electronic Tuning

- Engine Popularity (seems to be stagnant)

- HIGH COMPRESSION! (OUCH) (Although I could lower that with a properly designed cam to keep boost in and effective compression low or dished pistons of course, would like to NOT have to touch the motor)


The vehicle I would like to do this with is a G6 GTP, not sure Coupe or Sedan, I like them both. Either way I'd like to test it on a 6 speed, although we will need a clutch Im sure almost immediatly.

I honestly think GM should make a Turbo Version of this motor with Low Compression. 8.5:1 will make for some 400 WHP++ on a bone stock 3.8 SII with my turbo kit with no knock on pump gas.

I think the 3900 would make more, but it cannot due to its CR. I think 340 WHP will be its limit before knock (at best) However, I think that the motor could be a 430 whp motor if we didnt have a Knock issue. Or more. Why? Well If there can be lift achieved in the valvetrain, IE modified Rocker Ratio to ~ 1.9:1 or 1.85 and the VVT will allow for the power band to dip into the 6400 rpms, which make for some great horse numbers.

Additionally, the relativley low torque for this motor will allow for HP to be as high as the torque numbers, which will reduce strain on ALL of the components.

Unlikes the 3.8 SII which I've seen some people size some small turbos on that and get an excess of 500wtq Thats... A lot. For a stock anything.

So I IMPLORE anyone who can pop off thier 3900 and have thier heads flowed, or get Cam Spec info, I'd REALLY appreciate that.

I know the 3900 has a nice large Intake valve 1.87 which is .07 larger than the Series II 3.8, however they both share the same exhaust valve diameter size which indicates that GM knew they need more intake CFM than they had on a motor like the 3.8 SII which had a terrible Exhaust to intake flow of like 94% stock, it should be b/t 70% and 80%. But anyways enough ranting.!q

[Manitcor]

The 660 bottom end is much stronger than you think it is. And they have shown to be much less prone to knock issues than the L67 has.

There are turbo 3400s running 8-9psi and dynoing 280-290whp on stock bottom ends and 9.6:1 compression and mild porting.

In stock form the 3100 and 3400 can be a bit dissapointing and this is mainly due to, as you agree, GMs intention to make it an economical V6 engine. We have already seen however a 1/2 way decent head port job (not flowed or swirled) stiffer springs and a cam shifting at 6300-6500 has shown about 225whp.

The 3900 and the VVT 3500 are complete redesigns of the gm 660 and share more with the Gv6 line of engines than with the 3100/3400.

The main reason you dont see sub 12 second 660 engined cars is due to the fact that litteraly no one has ever put forth the money or resources that ZZP and Intense are putting toward the 3800.

Flow on the 3900 is greatly improved allthough I would agree it could almost always be better.

Higher compression is not as much an issue as you might think and it really depends upon what your planning todo. Due to the nature of where a turbo makes power and stresses the bottom end (mid-stroke, where as your worst stress points are at TDC and BDC particulary TDC of the exhaust stroke) you have to almost double the power of the engine with a turbo before the bottom end became a concern (between a 70-85% increase of stock power).

Theres more there than you think, many of us havent spent all the time and research we have if we didnt know it was a quite capable platform. Unfortunalty we just dont have the big money backing like the 3800 got so its more of a challenge for us to R&D and develop power. Now that ZZP is starting to support the 3400, 3500 and 3900 I expect that to change in time.

[SappySE107]

Got a stock 3800 flow sheet? I want to see what a "non garbage" head flows for .4 more displacement. And I would also like to see what you are basing ported heads flowing like garbage on.

[SappySE107]

Nevermind, I found it. http://www.thrashercharged.com/image...low_stock3.jpg

um, dude, our heads flow better than that stock.

[gpse3400]

Ben, I love it when people just pull numbers right out of there asses. Anyone else feel like making assumptions on things they know nothing about!!!???!!! Typical internet bs....