I was thinking of upgrading my throttle body to a Holley dual 52 or 58. My question is which one to go with? If I went with the 58x2 and did not add any other mods right now (except for in my sig) would I hurt performance with the bigger unit? I was thinking I might add the Lingenfelter manifold/runners/base this winter. I am open to suggestions!

:cheers:

 

I think they both would hurt your performance.

 

That's It?!? Why would they hurt my performance?

 

I put a Holley 52 mm on my modded LT1. The intake design is fairly decent and the car had headers already and the Hot Cam. I dyno'd a loss of 4 hp. Now this was a different dyno on a different day, so I can't say 100% that you will lose power, but I can be pretty confident in saying you won't gain anything.

Performance wise for me I didn't gain or lose anything at the track and it didn't help or hurt my driveability at all. Basically it's a real nice looking high polished piece. In the case of my motor it's the heads that are the restriction, not the intake. After the heads the TB MIGHT make a difference, I just don't know. Certainly the 58 won't, it's mathematically not possible for a 350 to need that much air unless it turns like 9000 rpms.

So with all of that said I don't think I would buy it again. I only bought it the first time because I got it REAL cheap. Otherwise it's a whole lot of money for just a polished TB that does nothing for performance. You will get a much better bang for the buck value out of a set of headers or a cam.

I know it's probably not what you want to hear, and it's not what Holley wants you to believe, but it's the truth.

 

One more note, on the hurting your performance. Not likely, but it can give you a decrease in throttle resolution. Basically with the larger TB it might feel a little quicker beccause the same amount of pedal travel allows more air in, but you will find that the engine is flowing it's maximum at 75% of the pedal travel, so the other 25 is just dead.

So essentially you shorten the useful travel of your pedal, so it feels a little more peppy down low, but on the top end you give it all back up. Thus you could actually suffer other issues like fuel economy and such because it will just be harder to give it "a little" throttle.

 

I agree with Nathan, if we don't open up the engine (heads, cam etc) the sbc can't handle the increse in air. I found a great book if want to dig down deep into the technical aspects of it, it's called "How to understand, service and modify CORVETTE fuel injection & electronic engine management". It's by Charles O. Probst . . . . . .


[Modified by edsalinas, 2:49 PM 7/7/2002]

 

What heads would anyone recomend?

 

Hmm, not real sure about that. I'm not from L98 land so I don't know for sure. I don't think you can go wrong with AFR heads, but they cost quite a bit.

Doesn't the 85 still have iron heads?

 

AFRs :yesnod:

 

85s have iron heads, so basically any aftermarket is better. I would get the AFR 190s though.

You can get the 52mm TB now, i just dont think it will help at all, and might hurt hp numbers, until you put a SR or the like on the engine.