Hybrid project need some help

[camaro_dakota]

I currently have a 95 camaro with the Iron head 3.4L. I have a block for a camaro and I have gen III aluminum heads and top end that I am going to put on. I know I will need to change the pistons.. but here is where my mind got away from me. I was wondering if I could use a 2.8L crank with 2.8L pistons sized for overbore equal to that of the 3.4L's bore size. This way it would be about a 3.1L destroked. So it would have a short stroke and large bore. All of this balanced and the crank hardened (ion nitrated or whatever) and knife edged with the big cam I have should rev high and produce some good power... Is this all that insane or can it be done? I know I will get the many people about why would you destroke... I just want to know if it will work with the old 2.8 crank. Thanks for any help I can get,
Dakota

[Wolf]

2.8 crank would probably pull the pistons down so far you'd have a redicusly low cr.

you could keep the iron head pistons in it to get a 12 to 1 cr,but you'd need to put a big cam in it to keep it from knocking

[v6h.o.]

2.8 crank would probably pull the pistons down so far you'd have a redicusly low cr.

no this is why he stated he'd use a set of pistons with the 2.8L wrist pin height.


the only problem is your not going to find pistons for a 2.8L that are .120 inch oversized.

you will need a custom piston, a regular 3.4L piston with the wrist pin location changed to the 2.8's compression height for the shorter 2.99 stroke.

i'd just keep it a 3.4L for all the trouble involved, yes building it as a shortstroke/large bore 3.1L would make some good high reving HP. but you want torque expecially in that Fbody which the 3.4L is great for.

[camaro_dakota]

I already have a 3800 stall and 3.73 gears and i think I am going to switch to 4.56's within the next couple months so i will be fine for low end. I want it to scream up top and I figure I need some custom pistons anyways so it would cost the same to get them like that. Thanks for the input. I appreciate all the help I can get. My car gets up and moves off the line, but what I'm really looking for is a pull up in the top end which my car lacks right now. Any other suggestions? My cam is the one for the 3.4L on the top of the page at www.ammperformance.com and I am using harlan sharp full roller 1.6 ratio rockers and mid-length headers on the alum heads... It should flow nice for some high revving power. I'd like to get some conversation on this because I think It would be an interresting project. Thanks again,
Dakota

[smilinguy99]

Re: Hybrid project need some help

... Is this all that insane or can it be done? I know I will get the many people about why would you destroke... I just want to know if it will work with the old 2.8 crank. Thanks for any help I can get,
Dakota

No, it is not insane, but if you were doing this for say, a drag racing class that is driven entirely by displacement and car weight it would make more sense. The small displacement with the G3 heads will allow you to raise the RPM where the maximum HP and torque is made and permit more HP per cubic inch than a 3.4, but less total HP. The main problem here (and the problem for the 60 degree V6 in general) is the weight of the car. If you were launching this car from maximum RPM, properly geared it would launch OK, but on the street, punching it from 25mph at 2000RPM it would be a disappointment.

Will it worK? Yes, but you would need custom made pistons. That's the easy part.

If this is to be used only on the street, go for the gusto (displacement) and just use a 3.4. You'll get more useful torque, and likely more HP.

If you are using a .5mm OS 3.4 block in both instances, (84mm stroke, and 76mm stroke) you are giving up nearly 20 cubic inches. At 1.1 HP per cubic inches, (a modest multiple) that is 22 HP. With more radical modifications that multiple can go up to 1.25 or 1.50 HP/ci. That could mean up to 30 HP. Wanna give that up?

This is one of those cool ideas that I wish someone would do, but it won't be me.

sg99

[v6h.o.]

if you do swap to the aluminum heads and intakes It WILL scream on the top end for power

trust me

i'd keep the displacement at 3.4L

[camaro_dakota]

would the flat top pistons from the iron head motor be ok to use with a .506 lift cam and the alum heads? If I have to use octane booster or something I dont care i was just worried about piston to valve clearance issues. I know I should prob go with the dished pistons but would it be ok? I think compression ratio would be somewhere in the 12.3:1 area but im not really sure. Thanks v6 h.o. you've pretty much got me convinced to keep the 3.4L displacement what about the pistons?

[RacerX11]

The iron head 3.4 does not use flattop pistons...they are dished. The dishes on these pistons do nothing for piston/valve clearance, since the valves touch the pistons first on the outer edge, where there is no dish.

Marty

[geoffinbc]

True they are dished. But only slightley. Nothing compared to alum head pistons.

[camaro_dakota]

Ok my bad I did know that they had a slight dish but compared to the alum head piston they are pretty much a flat top the dish is very small. I have a piston sitting in front of me. My question is will they be ok to work with that large of a cam....the whole valve cant hit the side of the piston so the larger dish might allow for extra clearance.. i dont know i have 12 of the iron head pistons and if I can use them then I can put the motor together next week.
Thanks for all the input keep it coming I really appreciate it. Anyone have any ideas on how to switch the camaro computer to maybe a grand am computer so I can get this thing tuned? I have ed wright custom tuning for a small cam on the iron head motor but this is gunna be a whole knew banana and ed wright stopped doing custom tuning for the 3.4L f-body (only does a generic tune now). Thanks again guys this is awesome,
Dakota

[RacerX11]

I will say it again: the dish will not help anything with piston to valve clearance...period. On the aluminum heads, the valve edge will touch the piston on the outer edge, WHERE THERE IS NO DISH. You could have a 1" deep dish, and it won't make a difference for valve clearance. It doesn't matter if the whole valve doesn't hit the piston...if any part touches, you are screwed.

You would need to assemble the engine with the cam and see if they clear. If not, you will have to cut valve reliefs in the pistons, or run a milder cam.

In my experience, runnning a cam with 0.506 valve lift, with these pistons, you are probably going to have problems.

Marty

[camaro_dakota]

That last part is what I was really looking for if there would be problems... I said i didnt exactly know if having a larger dish would help. Thank you for your help though....So now I have a new problem... how to get valve reliefs into the pistons.... I have never attempted making my own valve reliefs. I want to run this cam... It is a comp grind made for the motor and its on AMMperformances website www.ammperformance.com and it shows lift with a 1.5 ration rocker arm. I am using harlan sharp 1.6 roller rockers which will bring max lift to around .506. If i used the iron head pistons and ran compression in the 12.3:1 area how would my knock sensors be? Like when going from LT1 to LT4 heads and compression jumps to 11:1 for them they need LT4 knock modules.... I know thats kind of random, but im just trying to think of possible problems I may run into. I may just start assembling the short block and see what it all looks like. Let me know if you guys have any ideas or anything that might help me out with tuning and or suggestions about not to use the iron head pistons or to do it. Thanks for all the help and I could always use more lol so thank you,
Dakota

[BMC]

As far as cranks fitting in the block, the 1988 internal balanced 2.8L crank should bolt directly into your motor... Using those "2.8L 0.120 or larger overbore pistons" should prove to work fine for ping height and all that.
Currently, you say you are using 1.6 ratio rockers, and a big cam. Did you have to reprogram your PCM to work with those or are there any down sides to driveability? Who programs your current stock PCM anyways? I have been looking for someone to do that for one of my '95 Camaro 3.4 manual.
Thanks!
-BMC.

[camaro_dakota]

This big cam and the 1.6 rockers are what im using in the motor im building in my garage. I do have the crower baja beast cam in my iron head motor in the car right now and I am using the last custom tuned computer for the v6 f-body from ed wright at fast chips. He now does a generic tune mainly for stock or slightly modified cars like intake and exhaust. It sucks because i was really hoping to get him to tune this alum head big cam motor. Ohh well, thats why i was asking if anyone knew how to switch my computer to an older FWD computer so it can be tuned. As for driveability....its gunna have problems almost for sure. Its a large cam and a lot of parts that wont like to mix not to mention its all running through a high stall convertor. If you dont mind dealing with the small hassles that come with a big cam and stall then you should be fine. I ran a nice size cam on the motor before the one that is in the car now and its idle was soo chopped up, but it sounded so mean that it didnt bother me driving around. Only problem is the large cam didnt last too long as a daily driver with the old cam bearings and nitrous. So this time its new SBC cam bearings and its gunna be built the best I can with the most info i can get into making sure its a solid combo. Thanks for the info,
Dakota

[BMC]

http://www.v6mgb.com/uploads/!cid_3130787224_7985953.jpg
http://www.v6mgb.com/uploads/!cid_3130787224_7989973.jpg
Take a look at these. The Camaro 3.4L has been found to be one of the most diversly used motor that I have ever run across. Camaro owners with 3.4L motors still intact need to place dead bolts on the hoods of thier cars to keep MG, Sunbeam, Triumph, Porsche, Austin Healey, Fiero, S10 and many MANY more guys from taking all the motors.
Thank you Camaro owners....