Not sure if this is the correct section, but here goes; I am looking at a real nice 1985 IROC-Z, the guy claims it has a newly rebuilt 305TPI engine, 5 speed manual borg warner transmission, headers, speed pro pistons, comp cam camshaft, summit roller rockers, new exhaust ( Y pipe to flowmaster 80 series), and 3.42 gears. I was just wondering if anyone knew what the ballpark estimate would be for HP/TRQ? I know the '85 305TPI stock is 215HP/275TRQ, would those mods add an additional 30-40HP/TRQ? Here is the link for the car btw: http://harrisburg.craigslist.org/cto/2136667529.html

 

Doubtful.

TPI itself, the 305 itself, and the exhaust manifolds, are pretty much the limiting factors.

Looks like a decent car, although probably severely overpriced; except for the muffler, which you will HATE. I had one of those for a while and COULD NOT STAND IT, it was like dragging a 55-gallon drum behind me all the time. I cut it off and gave it away. IMO the gauges devalue it dramatically. Too bad it has that funky steering wheel and shifter, also.

 

Damn, I'd figure with the cam and headers, there would be a decent gain.

 

Something else to consider...

(a) The T5 was NOT offered in 1985 WITH TPI. Either the trans was swapped or the engine was not TPI originally.

(b) For $5600, you can get a really nice 91-92 Z28 which are a tad more refined and a lot of people prefer the 'newer' styling of the gfx and dash. Myself included.

Not saying its a bad deal, but honestly, that car would only be around $3500 here in East TN. The economy still sucks, despite what Washington says...

BTW: I agree that a 30-40hp gain with those mods is probably not realistic. 20hp maybe is closer.

 

Sorry; missed the headers in the list somehow.

Depending on the cam, it might be as much as 25HP over stock. But since Comp makes about a million different cams, it's anybody's guess, without the details. Might even make LESS than stock, if it's a poor cam choice (which is amazingly eeeezy to do with TPI - many otherwise "good" cams do not play well in the same sandbox with it), given also that the pistons that were used LOWERED the compression significantly.

 

so what's the best stock engine to look for with third gens? 350TPI or 350 carb?

 

Carb is cheaper to build, easier to tune as well and has less limiting factors.

 

There is no stock 350 engine with a carb, from one of these cars. Such a thing was never offered. The 350 was only offered starting in 87, and only with TPI.

Which is not the same as saying, there's no such thing as one of these cars with a carbed 350 IN IT; only, none came that way STOCK.

Wouldn't matter anyway. "Carb" or "FI" is not a property of the ENGINE. All it is, is the induction system bolted to the top of the ENGINE. You can take ANY ENGINE and bolt up EITHER.

So don't bother concerning yourself over what induction system is currently on an ENGINE; if it's a small block Chevy, you can put whatever you want on top.

If you have FI now, it's AHELLUVALOT CHEEEEEEEPER to stick with FI, than to swap to carb. Carbs are only cheeeeeper if you have NOTHING and are starting from scratch. No way buying an intake, carb, and distributor, plus doing a whole bunch of plumbing and wiring, is "cheeeeeeeper" than doing NOTHING and just putting it back like it came, or even, putting it back like it was AND fixing what came on it if it needs it.

But even all of that is wide of the mark you need to be shooting at. Carb vs FI is trivial. You're trying to BUY A CAR, not SWAP AN INDUCTION SYSTEM. Big difference.

The main thing is to keep the main thing the main thing. And the main thing is:

Find A GOOD CAR, and more specifically, AT A GOOD PRICE.

The car you posted, I would personally not consider a "good car": it's been hacked on extensively, and it's a 305/auto combo which means, even beyond just that inherent disappointment, it has poor gears in the rear. IMO it's FAR cheeeeper and eeeeeeezier to put a 350 in a 305 car, than to put a stick trans and decent rear gears in an auto car; so IMO the cars to be looking at are 305/5-speed TPI cars (NOT TBI) with G92 (the performance gear ratio package), and with AS LITTLE "CUSTOMIZATION" AS POSSIBLE. That car fails on all those counts.

And it fails on the other important criterion, "good price": that's about a $3000 car in most places, less in the South or West where rust is less of an issue and these cars have lasted better as a result.

Don't let shiny bright red paint, a PO's customizations, and a bunch of CL monkey-spank, dazzle you and distract you from what really matters. Let this owner enjoy his hallucination about what he thinks his car is "worth", and keep looking. He obviously likes the car too much to be ready to be an effective seller.