I am thinking about dropping a zz4 crate motor in my 91 305 TBI equiped firebird but I was wanting to know how fast I can expect to go in the 1/4 first. If I get one I would put a demon 700cfm or demon 750cfm carb on it. I would just put my exaust manifolds off my 305 on there. and I still have stock exaust. Just what kind of times should I expect?
Thanks!
Brent

 

mid to high 13s on average from what I've heard/read. But not with stock TBI exhaust manifolds, any stock exhaust manifold is bad, but the TBI mani is just about as bad as you can get.

The decent running ZZ4s will have headers, hi-flow or no cat, and good cat-back. Not to mention a decent intake setup. Choke it in any area and you'll severly hamper the engine's performance. And a 305 TBI exhaust is major bad news for performance on a good 350.

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

 

With a stock ZZ4, stock TPI, and headers, the best I could get was a 13.4 @ 99mph with a 1.78 60 foot.

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'91 Z28 Blue/Silver ZZ4/ZF6
335.9 rwhp 374.9 rwtorque

 

Yah, you'll probably hit high 13's with a zz4 w/stock manifolds. GET HEADERS and catback! It'll really unleash the beast!

 

yeah dont bother with the stock exhaust... unless u really feel llike findoing out what kinda difference there will be... god, even if u find some lb9 or l98 manifolds, get a cat back on it at least

Steve

 

i just gteched mine...
heres the stats:
2 people in the car..
2.77 rear gears
stock tpi
completely stock otherwise besides headers (and the zz4)
it also has a dying tranny..

my best run was 14.00 at 107mph (subtract 2-5 mph for gtech)

 

If tuned properly they should be low mid 13's. My 305 did the quarter The high 13's at 99.7-100, and it only made about 300 hp

 

doh!
dont tell me that
ltr,afpr,ported plenum here i come..

 

I'll be testing my new ZZ4/TBI motor very soon. I think you'll be interested to see the results because we both have RS's with the TBI setup. The motor will be dropped in this weekend. Woohoo!!

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'92 RS, ZZ4 10:1 350, Edelbrock 6085 heads, Crane 208/214 467/482 cam, GM 1.6 true roller rockers, Holley Projection TBI intake, Holley 670 TBI, SLP/Jet-Hot 1-5/8" headers, Catco 3" cat, Flowmaster 3" catback, Hughes 2500 stall converter, stock 700R4, Auburn Pro posi w/3.42, 17x9" SS rims w/BFG tires, Medium Quasar Blue w/white SS stripes, 48,000 miles....