So here's my crazy plans...

I have a 2.8L with a forged crank that is getting a rebuild, ARP bolts, MTC-5 cam, bored .030 over, Total Seal Gapless rings, SpeedPro cast pistons (unless I can find off the shelf forgings), short fill the block, the basics.....

It will also have a front mounted crank trigger and will use the computer from a FWD DIS OBDI 3100. It will get the gen 3 3100 top end ported and polished throughout with new springs and 1.6:1 roller tip rockers. I plan to take a few cc's out of the chamber in an effort to get the compression to 10:1 or as close as possible. For now I will run the stock manifolds to dumped glass pack mufflers. If detonation is a problem I can always through some E85 in the tank, but then I wear out my injectors faster... Its a pretty basic build and I'm hoping for about 200hp at the wheels (with no AC, no poewr steering, no smog pump, ram air intake, electric fan, and a manual transmission- all synthetic fluids). I know it seems like I'm asking for too much from a basic engine, but its only slightly over 1hp/ci at the wheels, and I've done a lot better than that in the past (though the cam may need to be changed to a more aggressive solid grind to get there).

 

hey I have a whole 3.1L engin and 5 speed trans that I pulled out of my old 91 chevy cavalier Z24 after a minivan decided that I didn't want the car any more in anycase I rebuilt the whole top end of the car new heads intake manifold and few others if you need anything send me a message (incase you didn't know the olny difference between the 2.8 and 3.1 was the stroke, everything else matches up on the motors

 

Are you putting a 3.1 crank in it or just boring it out?

Reason being, you can't use RWD 3.1 pistons on the aluminum heads. The pistons will hit the valves.

 

u can use the rwd pistons with fwd heads,the valves wont hit but will be afully close,but u will end up with around 14.3-1 cr

 

if you are using rwd pistions you won't be able to lower the compression to 10:1 by just opening up the chambers, the most you will get out of them is like 2-3cc with out killing the chamber shape. 2cc is worth about .2 in CR

 

I'll have a slight dish milled into the piston if need be, but I highly doubt it will actaully be 14:1 with untouched heads- maybe closer to 13:1- and even if I have to run closer to 12:1 I can just mix 50/50 93 octane with E85.

 

Why go through all the trouble of milling the cast pistons? The bore is the same in 2.8/3.1 so just use the pistons out of the motor your getting the heads from, or they are readily available. I would advise against taking any more material away from the stock jugs.

 

Dave has already done the calcs and found out! With expanding the combustion chambers (till there's hardly and material left), and using thicker head gaskets I think he was able to come down to 11:1.
If you're looking for high compression, it's easier to take the conventional route and use the dished pistons and have the head shaved.
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As far as the E85, I thought that the Ethynol fuels combusted at a lower compression (hence the 85 rating) which means you'll get detonation for sure. I could be wrong (have before) but I believe that's why E85 vehicles can run on either gas/E85 because their compression ratio is lower.

 

i can get u a set of brand new hyperetic 3.1 pistions for use with aluminum heads for 46$'s + shipping.
the stock pistions cannot be milled enough to drop the compression ratio.
the fwd pistons have a .050 larger in diamiter dish,and its .100 deeper.
even trying to remove .050 from a rwd pistion will result ina very thin piston top that will most definatly break.
trust me i already tried doing this

 

E85 gas has a higher octane rating, thats why hes talking about using it on a high compression motor.

IMO, you will need a more agressive cam then the mtc5 to net 200hp. Esp with stock manifolds.



I know my 3.4, mtc5, stock rwd heads, headers, catback was still under 200hp. I doubt the gen3's will make up for the ci and headers. But I may be wrong.

 

The 85 comes from 85% ethanol. The other 15% is still gasoline. Octane rating is between 100 and 105. Most of the time on the upper end of that.

 

Thanx, guys. So can all cars run on it then? We don't have it here in South FL yet, but I see the auto ads talking about the new cars being "E85 compatable".

 

No. The o2 sensor on our cars is not able to run it. As well I think the FPR needs to change. then also it requires a different air/fuel ratio then the normal gas 14.7 (I forget what it runs at).

Our cars can be made to run on it, I remember reading about a few canadian guys swapping. Several parts had to be changed along with new proms.

 

Cool, all those parts are going to be changed on my car anyways! Sure beats waiting in line at the track for race fuel!
Sorry to hijack your thread...lol
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Back to topic...

 

more needs to be changed that what was listed. I suggest going into the gen tech area and asking some of the guys that have converted what all was needed.

FYI no e85 here either. They say there should be some by end of this year. *rolls eyes*

 

dave, $46 for a new set, or $46 a piece? All standard overbores?

 

If your not going to boost your car, the hypereutectic would be a good cheap alternative to forged. Don't expect them to last long with a lot of detonation.
Dave, are they yours to sell, or are you going to give us a link?...

 

i have a set of pistons but there .75mm oversized and for iron heads.
i need to get on my other computer to get the link for the 46$ set of pistons,
they are for aluminum heads and i belive were standard size,though they may have been slightly oversized,once i get on my other computer ill post up the link and info.and yes the 46$ is for a full set

 

ok i was a lil off.
the 46$ sets are cast but are fine for what u are doing
they are .75mm oversized (.030)
http://cgi.ebay.com/ebaymotors/CHEVY...spagenameZWDVW
and here is a set
silvolite hyperetic with coated skirts
.50mm oversized (.020)
and these are 95$'s a set + 10 shipping
http://cgi.ebay.com/ebaymotors/Chevr...spagenameZWDVW

both of the above are for aluminum heads and will get a 8.9-1 cr

 

and I thought I'd just check to make sure you knew that stock RWD manifolds won't bolt up to those heads, so you'll still gotta find a way to make the stock FWD manifolds work ( I would imagine the FWD manifolds would dump in funny angles so that would be interesting )