dg8srt

Hi, I have a 94 Z28 that has ported and polished heads and intake, 1.6 rr, twin 58 mm throttle body, CAI, 3.73 gears, and pacesetter long tubes. I am planning on doing a cam and possibly e85 at the same time. I have my eye on the GM847 cam with a 2,800 stall. Will my gears work ok with that? Any better cams i should be looking at? Is it worth switching to E85 while I have it apart? I know i would need injectors, fuel pump, regulator, and a tune. Any help would be great.

bw_hunter

3.73 gears work with that cam and an automatic trans. Be sure to get a good tune...

Switching to E85 is a personal choice. With the drop in the price of gasoline, I wouldn't bother but that's me. Remember that your fuel economy suffers significantly switching to E85 so include that in calculations. The fuel economy loss comes from the relative energy content of the two fuels, pound for pound gasoline has far more energy available to unleash...

JakeRobb

E85 fuel has a very high octane rating. Generally 110-115. The rating is not very consistent, however, which makes tuning complicated.

There are two ways to take advantage of high octane fuel: more compression and more boost. More aggressive timing can make use of some of it, but not enough to be worthwhile IMO. Unless you planned on using E85 100% of the time, you'd have to have a way to switch tunes on the fly.

More compression means getting into the bottom end of your engine, and more boost is off the table unless you're interested in adding a supercharger or turbocharger.

So, I'm with Fred. Skip the E85.

IowaSS

What is your compression ratio? Unless it's a lot more than stock, that 847 cam is a poor choice. It's also too aggressive to be running with a 2800 TC. Is that TC a 9.5" unit? or a 12"?
The 847 is a very high rpm cam in a 350/355. If you decide to run it, plan on spending money on the valvetrain. SA rockers get iffy at the revs that cam needs to perform well. Plus, you don't want to turn those revs on a non-rebuilt stock bottom; it won't last long.
I'm running a smaller cam and still shifting at 7100 rpm for best performance. 4200 TC, guideplates & non-SA rockers, stiff pushrods.

Unless you're going with boost or extremely high compression, E85 is not a good idea. IMO, it's only a reasonable option to buying race gas. For an engine that can run on pump gas, it makes no sense. More expensive and more hassle.

Injuneer

Actually, you're with Bruce.

dg8srt

Thanks for all the great input! I am not sure of the compression ratio that the motor has right now, as the previous owner did all of that work and had it dyno'ed. After more reading I'm starting to think that e85 is probably not worth it. What do you guys recommend for a cam and converter for my car? I don't plan on getting into the bottom end any time soon, so I guess GM 847 may not be a good choice. I would like to add boost at some point, but thats a long ways down the road so i'm not too worried about that right now. Thanks

IowaSS

We'd be making a non-educated guess at cam & converter selection without knowing what compression it has. If you want to make an intelligent cam selection, you're either going to have to get the specifics from the builder, or pull a head and measure deck clearance and chamber volume yourself.
What did the car dyno? Are you sure it has the stock cam now? Answers to those two questions would help determine if the "ported and polished" heads really accomplished anything. "Ported and polished" intake, except for the 58mm openings, is worth zero.

dg8srt

that makes sense. the previous owner said it dyno'ed at 318 hp, i do not remember what torque was. But who knows, I have never seen the dyno sheet, he is in the process of finding it for me (i hope). He said it still had the stock cam, because he bought an extra set of heads that came with the car that he was going to send to a builder so he could make a cam for those heads. I may have to contact the business that dyno'ed it to see if they still have it on file, its been a few years so it will be a long shot. I may have to pull a head i guess.

dg8srt

Wouldn't the compression ratio still basically be stock? If the heads are actually ported would the ratio change that much from that alone?

Injuneer

Depends how big the valves are and what they had to do to the combustion chambers to unshroud them, and whether the heads were milled. But 318 at the rear wheels would seem to indicate a very superficial porting job, and most likely the stock cam.

Slayer

I have mods similar to yours, and this is the cam I have (Chevrolet Performance Hydraulic Roller Camshafts 19244485 - Free Shipping on Orders Over $99 at Summit Racing. I also have a 3,000 stall and a tune.

dg8srt

How do you like that cam? Decent mid range and high range gains? What did it put out for power?

Slayer

With all my mods, I'm putting down 375 at the wheels. I like the cam, but the power seems better on the low end, which could also be partly due to the tune for daily drivability. Because of my full 3" exhaust, you don't really know I have a cam unless you listen closely for it, which I like.

When I raced by friend, who owns a 2000 WS6 with headers, exhuast, 3.73s, a lid, and a tune (338 at the wheels), from a 60 mph roll, he walked all over me when we were both in overdrive. I kept it a lot closer when I was in drive, and he was in overdrive, but he still pulled away once we hit 125. From a dig, though, I'm pretty sure I can take him because I seem to have a lot of low-end power with my current setup.