TransAm12sec

My dad went to the dragstrip a few weekends ago with the 90 Formula.

Specs are

ZZ4
SLP runners
1 5/8 edelbrock Nickel plated headers
Random Tech Cat
Flowmaster catback
700R4, stock stall
2:73s
245/50/16 Radial T/As, 28 psi

The car ran mid 15s at 89 mph, with 60 fts ranging from 2.3 and up. My dad said he just spun the tires off the line. Do those times and the mph sound right?

unknown_host

iTrader: (1)

Assuming you are close to sea level, I would expect a zz4 to mph in the 103-104 mph range in the 1/4, even with a poor 60'.

TPI is killing that engine. I would recommend going to a different form of induction than TPI. Also, I would look into a looser torque converter, something like a lockup 3000 and drag radial like the BFG's or the new MT ET drag radials.

TransAm12sec

The car's a daily driver year round, including winter.

unknown_host

iTrader: (1)

Ok, I would look into a slightly looser converter then and still ditch the TPI. I don't think the car is going to lose any streetability with a 2000 stall and better induction. You are around 100 horsepower off from where your setup should be judging by the mph.

rolling-robert

get rid of the 2.73 axle and buy/beg/steal a 3.55 or 3.73 axle

five7kid

iTrader: (14)

A '90 = speed density. Any chip tuning? If not, the poor thing's extremely confused.

TransAm12sec

A chip was programmed for the car. The guy we bought it from has a chip made for it.

1989GTATransAm

iTrader: (3)

Yep, the gear ratio and stock converter are hurting your time. I would go with at least a 2400 stall. I agree with the above post on the axel ratio.

five7kid

iTrader: (14)

The gears and converter shouldn't have that much of an effect on MPH, though. They'll help ET, but it sounds to me like there's a power problem there - not all of which can be explained just by saying "TPI".

C&DPerformance

When my tranny blew I rebuilt it and put in a corvette TC and servo. It was a night and day difference. I went from a 2.0 sixty to a 1.8 and I think it runs and drives around town and on the highway better than ever.

bbtaz97

iTrader: (3)

something isnt right.. i ran those times with an out of tune 305 with 323 rear gears. even with the stock tpi he should be in the mid 14's no problem with a zz4 motor. I wonder if the chip is even close.

five7kid

iTrader: (14)

I'm with you on the chip. I've run 15.70 @ 90 mph with my 305 and no 2-3 shift, at 5800' altitude!

Something is seriously holding that poor engine back on power. And it ain't the simple fact that it's got TPI on top of it.

Section162

My car seems similar to the car in question, so I thought I'd post (see sig). My car goes 104+ on my G-tech.

Yes, TPI is probably holding us back, but not *that* much. And I burn my own chips, but I didn't need to do anything too radical.

I suspect there's some other mechanical problem that's holding the car back, and/or the chip you got wasn't tuned well at all.