Johngypsy

Got a 90 Iroc z, came with a 305 Tpi and a 5-spd, I am a parts supplier for 3rd gens, so I had some to all the parts needed to make it a real quick car,

Done this last year:

1) installed all brand new suspension sys, every nut & bolt, pan bar, adjustable all, new(er) 10 bolt 3.23 limited slip from 91 Rs, had a 1989 Trans am Gta come in, so the quest for a 5.7 was in mind, 2 weeks later, it was in my car, again new all, cleaned, painted, and looking nice, did a denisty swap at the same time, kept all wire harness, and added a 5.7 knock sensor and denisty,

Finally- added from my stash
1) 58 mm BBK performer tb
2) 1.6 short roller rockers to compinsate for the valve covers oem,
3) 255 walboro same as grand national
4) brand new cluch set from a bc4 police inceptor, same as 91rs L98,
5) 24 pond fuel injectors, adjustable fuel regulator,
6) msd 6AL,,,not yet installed, taken out because rpm went nuts, and damaged my sending unit for my cluster, so it's off for now,
7) flow master muffler, 3inch short exhaust to 2 inc out back to muffler,
Has factory cat, which is good,
8) hi voltage wires, 8mm, stock cap & rotor, & plugs gm ac Delco,
9) k&n air filters going to stock box inlet,
10) Slp siomise runners,
11) ported runners with it, intake ported, pentium also all 3 ported to gasket match set up.....

My mechanic adjusted the fuel to stay wide open at some where at 48 psi, he said I need more fuel? Also have stock headers,

My timing is off, it's not lab top, and stock ECM,
Did a test drive, it went 16.7 I'm the 1/4 mile, and felt like it was holding back, like if I had a truck and was pulling a house on my rear bumper, if I punch it in first gear, it's slow and feels like it was holding on to dear life, straining life if it's a old man trying to walk up 30 flights of stairs,,,, yea I laugh to.....

I need a good honest assessment of what's wrong here? What's my issue,
Thanks so much all you guys & gals. I would love to do atleast 13.8, I'm not asking for 12 sec car, I wish, but want it a little better then normal,

And also, with this combo? What's the proper cam and heads I need to do, I do have a friend who has a machine shop, and can do vortec heads from a 5.7 silverado truck, the shop will do the machine work to get it on right,
So please help me out, it would mean the world to me as I am a Iroc guy who just wants a decent power, and don't wanna be beaten by a 1991 Honda civic anymore!
John

OrangeBird

iTrader: (1)

At a first glance I see a restrictive 2 inch exhaust with what you mentioned as "stock headers" (Did you mean manifolds ?) , and an ECM that has not been tuned to take into account any of the modifications done thus far . Like Sofakingdom always says "find the first , worst , bottlneck and fix it . This will expose the next bottleneck , and so on until your making real power . Expect to $pend lots in the process" .....

The one I always liked was ;

Speed = Cubic Inches X Cubic Dollars . Squared .

Johngypsy

Yes it's a stock manifold, the computer is somewhat stock , had a guy do the lab top with a few tunes to compinsate with the previous work on the muffler, and do away with the vats, other then that, nothing els has been done,

The 2inch is from the muffler to the cat. And then 3 to the stock manifolds,
What's wrong? I wanted to get so much power from it, that it want backwards, I literally have up, almost 10 times, I was putting it for sale, and them taken off the market in 2 hours, thinking I wasent gonna give up, so I guess my next issue I wanna do, cam, heads, pistons, and springs to the heads, what all I already have, what size? What heads? Vortec or corvette style from the c4? Or any other that u guys tell me, is what I'm gonna atart ordering the next day,
But I don't want my car to rumble, or act if it was a nasecar, I herd the lt4 hot cam? But what ever you guys say, I'm going with, as I'm ready, like ASAP ready, also with headers too, but looking for the right match up with all I have,

Thanks guys so much!
John

Johngypsy

So sorry for the late response, I took off the 02 sensor, it was full of black dust and crud, it was really bad, my tps was set at .41, and my 58mm was turned up way hi?

I did the setting to .58, and changed the plugs, 02, and runs really nice now,

I just got new headman shortys today, and will put on later this month, as my stock MANAFOLDS, are not helping all these mods, so that's and I'll keep updates!

jrhaus76

Gears. 3.23 is ok. With a 5 speed, I'd go way up. I'm running 3.70s on an automatic.

I'm just finishing mine up but it runs really strong.

Dump the following items:

Smog pump. Get a shorter belt and take it out.

Cat.

Stock manifolds.

Stock "Y" (it's more a T) pipe.

Get it tuned on a dyno by a guy that knows these cars.