As mentioned in earlier posts, I am building a nice street engine for the IROC this winter along with some help from a good friend. What we have so far is a stock L98 shortblock out of a 1991 Corvette, and a set of Vortec cylinder heads.

What we have discussed thus far is:

1) Vortec TPI Base manifold, ASM runners, ported plenum, 24lb. inj., stock TB and a cam with a power range of 2000-6000RPM with a 2800RPM stall converter in the 700R4 and a 3.27 in the 9 bolt.

2) Ramjet intake, TB, rails, and 24lb. inj. with everything else being the same.

I think price wise the Ramjet stuff is not much more than the SD Vortec base and would make a flatter power curve.

Let me know what you think .... TIA.


------------------
Mike L.

1987 IROC Z 5.7 TPI A4 3.27 Borg-Warner four wheel disc
Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified airbox w/ K&N's, Relocated MAT sensor, Gutted MAF, 160* thermostat, MSD 6A, Accel 8mm Wires, bypassed TB coolant, 3" Flowmaster 3 chamber single outlet, custom adjustable cutout, 3" MAC mandrel intermediate, airfoil, ported plenum. !smog, Crane AFPR, Accel rail mounted FP gauge, Harlan shiftlite, 24lb. injectors, Hedman headers, a few others I forgot...??? FINALLY GOT PAINT!!

Check out my IROC webpage!

 

From personal experience, the TPI just doesn't like to rev. I have the ASM runners, ported plenum, and Edelbrock base, and it is still lacking in my opinion. Those runners are too damn long. If I had to do it over, I would look for something else, although there wasn't much else 10 years ago when I bout that crap in the first place.

------------------
91 Formula
Sportsman II's, Edelbrock intake, Arizona S/M runners, blah, blah, blah.

 

Mike, sounds like the Stealth Ram is pretty much out of the question?

I do like your combo except for the rearend gearing. My 3.73's get me through the traps at 5000 right when the power is starting to drop off of my stock TPI unit. I don't have the dyno numbers to substantiate this claim though, only the butt-dyno to tell me when it stops pulling hard. I don't know if you have seen my new track times yet but a 13.7 on this motor with bone stock cylinder heads (not even a bowl cleanup) and bone stock TPI pieces is pretty good. I would guarantee a sub 13.5 pass if I had ported the heads and intake pieces. This motor is pretty tame too, street driving is very tranquil. Not bad for a car that'll hang with a few of the slower LS1's

I like your combo #1 more than I do #2. What are you shooting for, 12's?

------------------
-Brad C?
355ci '89 Iroc-Z Red, T-tops, power everything, A4,New 10 bolt w/ 3.73's
Trans-Go shift kit Corvette Servo,Accel 8.8mm wires,Flowmaster 80 series ,K&N's, !MAF Screens, Hollowed out airboxes,homemade Subframes. Kieth Black pistons 10.3:1, Comp Cams 270H (.495/.502 218*/224* 110*LSA) & valve springs, SLP 1 3/4" headers, TCI 2400 stall, Dual Roller timing chain, 2 3/4" I-pipe.
Full street trim best run:14.799/mph:93/60': 2.02 (last year) New Times to come.
New times: 13.732 @ 99.30 on a 1.878 60'
Pics of the Iroc

 

Brad,

I'm trying for mid 12's on motor and low 11's on hose. We may twin turbo it ina few years, but so far I want to get it running good on spray.

The heads are going to be milled down to achieve a 10:1 CR. The Ramjet manifold will bolt right on the Vortec heads, and a Stealth Ram won't work with them. I wish it would....

Ever look at the Crate Ramjets specs? It make 350HP with a cam just slightly bigger than a stock L98 cam. Just think if I could replicate if with iron heads of the same design! Throw in a bigger cam, a little more compression, and a good set of headers and 12's shouldn't be hard at all.

The intake part is what I'm stuck on... I'd love to pop the hood and be able to say its all stock

BTW- Congrats on breaking in the 13's! Ever consider siamesing the base runners? You will be able to run higher rpms with it. Still look stock

Later,

------------------
Mike L.

1987 IROC Z 5.7 TPI A4 3.27 Borg-Warner four wheel disc
Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified airbox w/ K&N's, Relocated MAT sensor, Gutted MAF, 160* thermostat, MSD 6A, Accel 8mm Wires, bypassed TB coolant, 3" Flowmaster 3 chamber single outlet, custom adjustable cutout, 3" MAC mandrel intermediate, airfoil, ported plenum. !smog, Crane AFPR, Accel rail mounted FP gauge, Harlan shiftlite, 24lb. injectors, Hedman headers, a few others I forgot...??? FINALLY GOT PAINT!!

Check out my IROC webpage!

 

Sounds as if you are using the stock pistons? I bought the Summit rebuild kit but specified what I wanted in the kit and ended up with the 10.3:1 ratio. The Kieth Black pistons had a really deep valve relief setup so I didn't have to worry much about those issues. On the other hand they also offered a TRW forged piston for the same price. Just a thought. Costs $386 for the whole rebuild kit.

Anyway, I still think that 3.27 gear ratio is gonna kill you at the track. My 3.73's put me at 5000 at the traps. Thats about where the TPI stops making power with this cam... again according to the butt-dyno.

Just throwing out suggestions for ya Mike. You will be at the Woodward Dream Cruise tomorrow right? If so I'll see ya there. Email me your cell phone number, if you have one of these confounded things, and perhaps we could find eachother tomorrow.

 

Well be like me and use a RamJet intake Definately less than aftrmarket TPI bases and runners. The intake itself is at an OK price(~$400-430) but all of the little stuff to get it running is a PITA. Cost ads up for sure... Add a hotcam down the road maybe aye?? or something bigger like a 230/236 comp piece....560 lift maybe. A few magazines did this and got a good 15 more hp than a hotcam. later man!! You got a lot of time if this is a winter project!!

 

I just had a friend give me this cam today. It had less than 10,000 miles on it.
PN#10185071
208/221
.474/.510
.510/.544
112deg ZZ3 cam

Comments?

 

Hell, that'll work! Mild duration with some nice lift. It'll be a street beast I'm suprized more people don't use that cam since GM sells it really cheap(right?). See ya at the cruise!

------------------
Denny Villemure
1989 Camaro IROC-Z Convertible, 305 TPI, 2.73 Gear, Flowmaster 2 chamber. 15.60 on motor, 14.20 on a 75 shot from NX. Woo hoo!
www.denny.cz28.com

 

Mike I assume that those numbers are with a 1.5 and 1.6 rocker respectively. Very nice lift numbers! I like the duration also. The 112 should give you good vacuum too! How much do those cost brand new? Maybe I should have gone with that?!

Nice choice, it'll compliment the Vortec's nicely IMO.

 

Try www.LT1intake.com , He mods LT1 intakes to fit L98(tpi)motors.Just a thought.

later