3.4 Hybrid Camaro Engine Project - Questions

[SCREECH]

Greetings, everyone! I was on these forums shortly before they were packed up and moved a while back, and just got around to reregistering now.

Anyway, here's what I'm working on: My 1990 Celebrity Eurosport Wagon has had it's 3.1 and 4T60 removed and I've got a 1990 Cavalier with a 3.1 and Getrag 5TM40 5-speed that I'm pulling to put in the wagon. I just picked up a 3.4L from a '94 Camaro last night and will be using that engine with the 5-speed in the wagon.

Some important questions have come up:
1- I was told by the guy that I got the 3.4L from that he heard that the iron heads had 48cc chambers. I confirmed from domesticcrew.com that the old iron GenI 60º heads had this volume of chamber. However, that doesn't confirm the '93-'95 Camaro 3.4L head chamber volume for me. Anyone know if this is the same?

2- The same guy told me that the aluminum GenII heads had 28cc chambers. I found this info to be true according to domesticcrew.com. What this guy told me also was that I could drop the aluminum GenII heads onto the 3.4L Camaro block to up the compression almost 2 points. True/not/bad idea? Thoughts?

3- The 3.4L Camaro engine, although not being a 3400, is an SFI motor. Again, referring to domesticcrew.com (I spent some time there tonight, can you tell?) the SFI setup diverts back to MPFI at higher RPMs. And I've noticed a member on this board with a 3100MPFI (nice job on the manifold in the avatar picture, btw, whoever you are!). I also noticed that the recommendation for swapping a GenIII motor into an originally-GenII-equipped car was to re-use the GenII MPFI ECU and harness. Would I be better to do this for this 3.4L, drop the SFI for the MPFI? How would this affect the advertised power of 160HP & 200lb/ft, if at all? Advantages/disadvantages/thoughts?

4- I've seen some aftermarket sources for 3.1L forged cranks. Since the 3.4L has the same stroke, does anyone know for sure if it's the same crank, or could I get away with making such a crank fit/work?

I know this is a lot to throw out for a second post, guys, and I thank you for your time and any assistance/info you can provide me with these questions. I may have a few more come up later, but these are the immediately pressing questions. Thanks.

[RacerX11]

Here are some answers:

1- The iron head combustion chambers are the same for all 2.8/3.1/3.4 engines. There were no changes over the years. I am not sure if the 48cc number is correct, but it is close. If your source can verify this for a 3.1 head, it will be the same for a 3.4 head.

2- Gen2/3 aluminum heads on a 3.4 Camaro shortblock will give you ~12.5:1 CR, which is a tad on the high side for pump gas.

3- The SFI won't gain you any power. It will only help emissions, and give you a smoother idle, and slightly better fuel economy. Using the gen2 OBD1 ECU and harness is the better way to go, especially since they are tunable.

4- The 3.1 and 3.4 use the exact same crank. Thee is no reason to invest in the forged crank.

Marty

[geoffinbc]

So your putting a RWD block in a FWD car. HMM I hope you've researched the differences in the blocks.

So anyway ALL iron heads were the same after 1986 when they all got larger valves. After that there were never any changes. Aluminum heads will not be feasable without new pistons from a FWD Al motor. I would stick with the injection system already in the car. Much easier way to go. Plus without the SFI system you can use ANY camshaft, within reason of course.

[Guest]

Glad to hear that someone is using the Domestic Crew site.

Just to reiterate:

1. As Marty has said all genI (iron head) have the same combustion chamber size, there is a decrepancy though between 48cc and 52cc, my research indicates 48cc. Unfortunatly I don't have any iron heads to measure them.

2. Again, as Marty said the static compression ratio will go up, to between 12:1 to 13:1, also depending on the head gasket thickness you use. This may be a little high, but I don't know of anyone that has actually tried this high, just speculation. I do know of at least one person that is running around 11:1 with his 3.1 hybrid, on pump gas and no issues there, it actually runs well, he is now upgrading from the early 3100 top end to the later 3100/3400 top end, for more flow potential. I run 8.9:1 static with mine, but with the boost that I am running I have an effective compression ratio of about 12.5:1, I run on 94 octane pump gas, and get some detonation sometimes, but I am also running N/A timing, so there is no boost retard. Although this will act a little different than an N/A engine with the same static CR.

3. I believe that intake is actually photoshopped, it does look good though, eh?
The J-body swappers are running the original MPFI ECMs and have had very few issues, mostly just running rich at idle, in some cases where fuel tuning was not done. I too am running a J-body MPFI ECM with my hybrid, and save a few issues that actual turbo tuning will solve, it runs very well.

4. Yes, same crank, and as Marty has mentioned there is no need to get a forged crank, at least not at this point. I have yet to hear of anyone breaking or snapping a large journal crank. (1986+ 660 cranks are all large journal). Incidentily, I think I can see why, the large journal crank has journals larger than a SBC, by almost .020", how many SBC cranks do you hear snapping?

5. (Yeah I know there was no 5), Betterthanyou has eluded to the starter location, which with a longitudily mounted engine is on the wrong side, would be towards the firewall in a transverse application. You will need to drill and tap the bellhousing ear on the opposite side for starter mounting. I believe Rodney Dickman sells a jig to do this. Also if you are using an automatic transaxle you will need to clearance the bellhousing ear that sits towards the firewall. It's a triangular piece that gets cut off the bottom of the ear. Compare your 3.4 block and your FWD block and you will see.

6. The mount bosses in the side of the block are different, on the side towards the firewall wall, the mount should bolt on fine, but I don't remember exactly how the A-body mounts looked to comment on the other side, I do remember that it is different than the J-body though, and this might be a moot point.

[SCREECH]

So your putting a RWD block in a FWD car. HMM I hope you've researched the differences in the blocks.

Betterthanyou has eluded to the starter location, which with a longitudily mounted engine is on the wrong side, would be towards the firewall in a transverse application. You will need to drill and tap the bellhousing ear on the opposite side for starter mounting.

I have done considerable reasearch (which is what I'm continuing to do with the help of you guys! THANKS!). I know about the need to redrill the back of the block for the starter swap (although I've been thinking about getting around this by putting a crank start out front, you know, like the old Model Ts! ) I'll be using the 5-speed transaxle, so I am not aware of any other mods required in this regard. I guess I will discover them along the way! Ain't modding fun?!?


So we've established that that definately the CR will be rasied well beyond 11:1, possibly above 12:1 with the aluminum heads on the 3.4 shortblock with no other changes.

Aluminum heads will not be feasable without new pistons from a FWD Al motor.

Are you saying this because of the ungodly CR that will be produced? I'm hoping that I would be able to pull this off somehow. I know that aluminum heads make an engine a little more forgiving as far as a high CR ratio goes while running on something less than racing fuel. Would it be possible to bring the CR down slightly using a really thick head gasket, or would it be possible or even wise to consider using more than one? I've never tried this, so I just thought I'd throw it out there. If it'd be better to get one really thick one, any ideas as to where to look for that?


Also, no forged crank. Got it.


I like the idea of not having to swap parts of the harness to incorporate SFI. How about Mass Air versus Speed Density? The '90 Celeb's 3.1 was SD. I have been told that MAF allows more changes without ECU reprogramming. Which, in your guys' opinions, is the best way to go for such a project as this?

Unfortunatly I don't have any iron heads to measure them.

I'll be doing this with both the aluminum and iron heads once they're both off. I'll post my findings.

The mount bosses in the side of the block are different...I don't remember exactly how the A-body mounts looked

I've enclosed the following picture which shows where the 660 motors mount in the A-body chassis. Remember, the A-bodies have that lovely removeable engine cradle!

The engine mount underneath the balancer bolts to the siderail of the removeable frame cradle, and the dogbone connects to the upper rad support. Neither seem to use the holes for the side mounts as found on the RWD application. Other than those 2 mounts, the others are on the transaxle! I'm therefore not expecting much in the way of problems with mounting the 3.4L transversely, but we'll see when I actually get into it. For what I paid for the engine (essentially nothing) I figured it was worth a try at the very least!

[geoffinbc]

Yes I was saying the heads would not be fesable because of the compression. But for sure if you go ahead with the build use head gaskets form an aluminum engine. They are thiscker and therefore will help lower the compression a bit.

[RidgeRunner]

1. As Marty has said all genI (iron head) have the same combustion chamber size, there is a decrepancy though between 48cc and 52cc, my research indicates 48cc. Unfortunatly I don't have any iron heads to measure them.

I do, what's it take to measure?

[Guest]

1. As Marty has said all genI (iron head) have the same combustion chamber size, there is a decrepancy though between 48cc and 52cc, my research indicates 48cc. Unfortunatly I don't have any iron heads to measure them.

I do, what's it take to measure?

A piece of plexi with a hole, a graduated syring (we don't want any under educated syringes, right? ), some water and time, I think you get the idea, I know there's some info somewhere on a site, but can't remember which site right now.

Yeah for some reason I was thinking the A-body used that lower mount. The only thing I can think of that might be a delay, is the bolt that attaches to the front side of the engine (towards the rad), I don't know if theis location was changed on the 3.4 or not, I just know that it was on the genIII engines. So yeah mounts should be much of an issue if at all.

[SCREECH]

I don't have any iron heads to measure them.

I do, what's it take to measure?

I've got a REALLY old page (still hosted by my dial-up provider!) on which I have some tech articles posted. I will eventually move them over to screech.ws once I get my new server. Go to the link below, click on TECH TIPS on the left side of the screen, then go to the first one on Measuring Your Combustion Chambers. It's got pictures, diagrams, and even the formula for converting ci to cc.

Screech's '73-'77 GM A/G Body Page

http://www.mergetel.com/~lee/73-77ag/