New to forums S10 pickup. compression questions

[slugbeast]

Hey everyone! I've been watching the site for more than a year and finally registered for the forum now that i am getting ready to do some serious mods the the engine itself.

I have an s10 with the 2.8 tbi with 600,000 miles on it, and have parked it due to leaky head gasket, bad clutch release bearing, exhaust leaks due to broken off header bolts that cant be drilled out and leaking water pump with broken off bolts... But i'm getting ready to do a swap for a mpfi 3.4. My old boss is about to get rid of his 94' firebird with the 3.4 or if he doesn't i'll just get one from the junkyard.

SO... here is the big question i have.

if i have the heads machined down, what compression should i run it at? I live in florida so there are no emmisions or inspections of any kind. what octane for what compression ratio? and when will i have to run methanol? is methanol worth the trouble?(i want your opinions) for example could i get away 14:1 with 93 octane? If i did decide to go the methanol route whats the max compression i could run with it?

I was hoping to keep stock pistons with chromoly rings, is that wishful thinking or would i have to get hypereutic or forged? and at what point.

Thanks in advance. -Ben

[robertisaar]

first off, welcome.

second, 600K miles: WOW.

to answer at least some of your questions: depending on how much time/effort/money you want to throw towards tuning, you could run on any grade of fuel, but you would have to pull significant amounts of timing to run a lot of compression on low grade fuel, killing power and economy. move up to any higher octane and it will allow for more spark advance, and more is better until you reach a point where more spark actually takes away power, but at 14:1 compression, i doubt you would be able to hit that threshold with pump gas.

methanol requires a LOT of fuel since it's stoich ratio is 6.4:1. it would allow for a lot of compression, but i wouldn't advise it unless you don't plan on driving it a lot. great for a track toy, but that's about it.

the stock pistons should be hypereutic, but don't quote me on that.

if you're looking for a lot more power, you may be better off using a FWD top end, since the heads and intakes flow a LOT better than the RWD setup.

[slugbeast]

interesting. methanol isnt gonna happen then but i think i could definitely do with machining down the heads to 13-14:1 compression, still sounds like a good idea to me.

I've have read a bit into the top end swaps from the 3400's to the 3.4 rwd motor, it was my understanding that they bolt right up. What i am wondering is what computer and fuel system i would run with it. assuming i start with a running 3.4 from a 94 firebird would i just be able to hook the throttle body and fuel rail and all that to the intake manifold and heads from the firebird engine or would i have to use 3400 components for that fuel management stuff? i guess i just want an elaboration now of how to do a 3400 top end swap. and also those are dohc right? i see on summit the lifters are the same (on a 96 grand prix 3400) as a 3.4 but i didn't see any cams or roller rockers for sale on the site. if i couldn't get cam or 1.6 ratio roller rockers then is the 3400 top end really an improvement? Wot tech does have a cam but its like 350 bucks and no roller rockers, is 3400 already full roller?

[robertisaar]

the 3400 stuff doesn't bolt right up, but it isn't too complicated to get it to work, i think just custom pushrods, but this is a much better resource than i am:

http://www.domesticcrew.com/660/hybrid.html

computer: could use any number of OBD1 ECMs, but a 1227727 or 1227730 would be easiest.

fuel: i'm not sure if the stock fuel pump from a S10 will flow enough to get the 43.5psi required for MPFI....

the 3400s are NOT DOHC, that would be the LQ1 (3.4 only in 91-97 W-bodies).

the lifters of a 3.4(RWD OHV) are not the same as the 3400 lifters, since the 3.4 is a flat-tappet motor, much like the one currently in your S10. the 3400s have roller lifters and rockers from the factory. the rockers aren't full roller(no roller tip), but they are better than the 93-96 3x00 rockers. if you use the bottom end of a 2.8 or 3.4, then you would be using a flat tappet cam anyways. comp makes a few, and you can get custom grinds from WOT-Tech or 60inclusive.

the 3400 rockers are already 1.6:1

did i miss anything?

[slugbeast]

yeah the fuel pumps are no where near what it needs to be for mpfi. we're looking at 9-13 psi on a stock one... thats a bit of an issue. crap... i wonder if the firebird's pump will fit the s10's tank. and i hate changing fuel pumps, its a pain in the ass.

throttle cable off a beretta, fuel rails, fuel lines, ect sensor whatever that is, and actually locating and aquiring the 3400 parts, i'd call this an extensive project, much more extensive than my origional slap on a few performance parts to the 3.4 and have some machining and computer timing work done plan.

OKAY... so lets go back a bit;

If i were to do the 3400 fwd top end onto the 3.4 and compare it to the machine work i would have someone else do on the 3.4 rwd top end (porting, valve undercutting) and assuming i put the 1.6 roller tips on the 3.4 how much more power am i actually looking at with the 3400 stuff?

and thanks for the fast replys!