darwinprice

I have a 1987 Iroc with a 355 sbc that was chassis dynoed at 356 hp at the rear wheels. It has a Coan TH400 with a 4500 stall. Moser 9" with 4.11 gears and steel spool. Spohn torque arm, control arms, panhard bar and anti roll bar. It also QA1 coilover shocks with 150 lb springs. He launches at 3800 rpms on the trans brake and shifts at 6000 and goes through the traps at 6200 My sons best pass has been 11.62 @ 115.50 mph. 60ft 1.52 330ft 4.72 1/8 mile 7.39 @ 92.36 mph. Our first pass of this year we ran 12.30 @ 112 mph. We were hoping to get the car down to 11.5 before the end of the race season. We have tried various things but have not gotten there yet. Are we dreaming or could this reached with the combination that we have. Any suggestions would be appreciated.

AlkyIROC

Race weight? It's always easier to get rid of weight than it is to make power.

darwinprice

That is something that we had planned on doing this winter. This car is still street legal so it has a lot weight that we can shed because we no longer are planning on running it on the street. I think that we have made some good progress just by playing around with the rear suspension and shift points. We have only been able to make it to 2 test n tunes so far. We travel a lot with a top alcohol dragster team so we have pretty much only been able to race on sundays when we can.

RS Chris

A few questions:

1. What were the differences between the 11.62 pass and the 12.30 pass? What did the rest of the pass look like, 60 ft., eighth mile wise?

2. What rpm did it chassis dyno at?

Only thing I would have done differently setup wise is a Turbo 350 over the 400, but that's just personal preference.

heavy_chevy29

what kind of heads, cam, intake is on that motor. 356hp should yield you a low 12 sec pass if the car is around 3200-3400lbs. the TH350 may have been the better choice weight wise for now but down the road when you are making bigger power the 400 is better. I would try playing with launch rpm and shift rpm.

darwinprice

My sons 12.30 pass was 60ft 1.83 330ft 5.19 1/8 ET 7.97 @ 88.79 mph. The dyno RPM was 6250.

darwinprice

The heads World SR that have been ported and bowl blended, the cam is a Comp Cam mechanical flat tappet 4/7 swap. 3000 to 6800 rpm. LS 106; Duration: Int 278 Exh 280; Duration @ .050 Int 248 Exh 250. Valve lift: Int .531 Exh .525. I am running Comp 1.6 roller rockers. The intake is a CNC Victor Jr that is port matched to the heads. The carb is Quick Fuel 750 with annular boosters. We are running low 11.60's @ 115 mph. My motor is an ex circle track motor that I got very good deal on. It was fresh out of the machine shop so the cam is a circle track cam.

AlkyIROC

The stall speed is a little high for that camshaft. A stall speed in the 3500-4000 range would be better. You could also switch to a camshaft with more duration to help with the 4500 stall converter. Something closer to 300* advertised.

darwinprice

I was told the same thing about the cam when I had it on the dyno. I am going to replace the cam this winter. I only paid 2500.00 for the motor so I wanted to see how the car would run before I made any more investments in that motor.

Orr89RocZ

iTrader: (20)

I dont think its overstalled at all.

Did you try launching higher and lower than 3800?

darwinprice

We tried launching at 3500 but we haven't tried any higher than 3800. When we launched at 3500 we ran no better than 11.90's. I was wanting to try and launch at 4000 but my son is on the road until after the last NHRA race in Pamona, CA so we are done racing for this year.

Orr89RocZ

iTrader: (20)

Its not a small cam. Its a 355. They dont make alot of torque. Everything is higher in the rpm range, 4500-5000 often times. Think for most small cube motors 4000 stall is minimum starting point. 3500 produced 3 tenths less et that tells you something.

Hit it harder

GCrites80s

Add me to the TH350 camp. Put the 400 on a shelf until you're putting up bigger numbers do to power-eating and weight concerns.

rb85TA

Cam, solid roller with a tad more dur.@. 050 (252/258... +\-) & .600 lift ( should put the cam at the top end of the heads capabilities ), 12.5-13.5:1 compression ( not a street car anymore, running only race fuel ), LOOSE WEIGHT (on the car side, nothing personal ), launch at 42-4500, tire psi ( according to track conditions ) & let her rip

darwinprice

Our plans for this winter was to do some engine mods. A solid roller cam and new heads were in the plans, but I wasn't planning on doing anything with the bottom end. The alcohol team that we work with own a machine shop and they are a Dart dealer so we can Dart parts at their cost as well as any other brand of engine parts. As far as weight both the car and I could stand to lose some weight but my son drives it so the car it is lol.

rb85TA

Right on, I just sent a set of dart pro1 ( pre-platinum series ) head's to SRH (Speier Racing Head's) to get his 248cc runner cbc program done, 2.100/1.600 valve combo. .. for my street /strip 422cid sbc.
He just did a similar set for someone else & they were 242cc 2.100/1.600.... flowed 340 cfm

TTOP350

iTrader: (8)

Dealer cost eh????? Did we just become best friends??? lol

rb85TA

LOL! nah just saying that I like the dart stuff (amongst many others I can't afford ).
& it sounds like you've got the inside track on some good stuff