[steve]

1981 firebird street only car. This was set up a little at a time so may be a slightly mismatched. Curious what you guys think. Let me know what I’ve left out. Looking for any glaring issues not necessarily perfection.

1981 Firebird at about 4000lbs
488 cubic inch Pontiac engine making 430 rwhp @ 3000rpm 130 mph, 592 crank hp
10.95 compression
72cc Eheads ported to 315-320cfm, 1.5 scorpion rockers
Northwind intake
Hyd roller cam 246/252 114 .600 lift
Dougs headers, 2.5” exhaust, dynomax turbo mufflers
3:55 moser rear
275/40/18 tires (app. 26”)
TH400 built transmission, unknown shift kit
2200-2400 tci converter
Dennys driveshaft
Holley Terminator efi
Engine was built to run AC but is not hooked up yet
March pulley set up, electric fan
Viking adjustable shocks, front coil overs

I don’t ever take it over about 5500 rpm’s and I don’t think I’ve ever had it over 100mph. I normally drive rather conservatively but it sees a good bit of “off the line” rips.

[dhcarguy]

Does it run on pump gas?

[Jay S]

Should be a fun ride.

Only thing that is mismatched is the stockish tci converter. The engine would like a 3500 or 4000 stall. But if it already can spin the tires on the street now, not much reason to change it.

[steve]

Runs on 93 but I put Sunoco 94 in it. Spins the tires all day long. Big smoky burnouts. It won’t fry the tires for like 500ft like I see some cars do though.

[grivera]

Badass! 162 hp loss from crank to wheels? It made max RWHP at 3k rpm or was that just for reference, meaning less hp loss from crank to wheel.

[78w72]

For a "street only car" that is a very powerful combo of parts at almost 600hp, some of the parts are more geared for racing, but sounds like a nice set up either way.

If it runs good and is reliable as is and is "street only", Id probably be more than happy with the car/engine as is, maybe a converter change as mentioned... but with 3.55 gears & 600lb/ft or torque for a street car, you dont really need higher stall converter. Maybe concentrate on other areas like paint or interior etc since the engine/driveline seem to be beyond what can actually be used on the street.

[steve25]

The only thing see that will come about is that .600” lift will take it toll on the valve springs in time .

[Jay S]

3000 RPM was likely the drum speed on the wheel dyno, which is close to 6000 engine RPM with the driveline specs.

[OCMDGTO]

Originally Posted by 78w72

For a "street only car" that is a very powerful combo of parts at almost 600hp, some of the parts are more geared for racing, but sounds like a nice set up either way.

If it runs good and is reliable as is and is "street only", Id probably be more than happy with the car/engine as is, maybe a converter change as mentioned... but with 3.55 gears & 600lb/ft or torque for a street car, you dont really need higher stall converter. Maybe concentrate on other areas like paint or interior etc since the engine/driveline seem to be beyond what can actually be used on the street.

My spare engine dynoed 569/631 and it was a DOG off the line until I changed converters. It was a night and day change to the car. I agree an ideal stall would probably be close to 4000.

It sounds like you're running good so I wouldn't change anything unless you're chasing a timeslip.

[steve]

I’ll post the dyno sheet when i get home. You guys know more about that stuff than me. I do remember the guy doing the dyno saying there was more power there but not sure what that meant. It’s true there is more power than I can really use at this point. I can’t afford to lose my license for doing like 120mph in a 45 zone. Most of my spirited driving is under like 75mph. Not to mention it’s a bit scary going that fast in a car without modern safety features. I still have the OE seatbelts. Fixing that is next !

[Goatracer1]

i agree you might be happier with a looser converter. I also think you would be better off with a over drive and lockup converter. That will keep engine heat down especially on the highway. I went from a built T400 to a 200-4R with lockup in my 600hp GTO and the car stopped running hot on the highway.

[78w72]

Originally Posted by OCMDGTO

My spare engine dynoed 569/631 and it was a DOG off the line until I changed converters. It was a night and day change to the car. I agree an ideal stall would probably be close to 4000.

It sounds like you're running good so I wouldn't change anything unless you're chasing a timeslip.

4000stall for a street only car? Im sure that will get off the line better than a lower rpm or stock converter... but with 3.55 gears & a torquey 488cid pontiac, a 4000 converter is overkill and would be very expensive for a high quality tight converter for street use.

I had a close to stock 1974 455 in a 78 TA that had stock gears & converter when I first got it and would easily smoke the tires out of the hole or from a slow roll in 1st gear getting a nice 2nd gear scratch. A few years later I did a budget rebuild with a mild .480 lift comp cam some basic engine parts like performer intake, holley carb, headers etc, probably 425hp/500tq, with the stock 3.42 gears and a cheap b&m "torque master" converter that was about 1000 higher than stock ~2200-2500 stall... it would easily smolder the tires from a stop at 1/2-3/4 throttle or 15-20mph punch and continue spinning into 2nd gear, couldnt use most the power on the street with street tires.

Im sure a higher stall would be a benefit over what he has now, but on the street the car cant really use the power it has now, current converter should be more than enough for a dedicated street car.

[ta man]

Originally Posted by steve25

The only thing see that will come about is that .600” lift will take it toll on the valve springs in time .

Depends on the valve springs..when Dave Bisschop redid my a few years ago the old valve springs were fine. There are lots of good valve spring choices out there for higher valve lift setups. I've ran mid .6 valve lifts for 15 plus years with zero problems.

[Skip Fix]

Originally Posted by Jay S

Should be a fun ride.

Only thing that is mismatched is the stockish tci converter. The engine would like a 3500 or 4000 stall. But if it already can spin the tires on the street now, not much reason to change it.

This! The old Continental 10" was tight but flashes to 3000 well.
I would bet the HP peak is well above 5500 with that cam and heads.

[steve]

I agree I would love an OD trans but being retired now I don’t think it’s in the budget for a while. Here is the dyno for anyone interested. I did post this a few months ago. The guy doing the dyno did say there was more power there whatever that means. The valve springs are listed as “130@1.85 springs 1.080CB 1.460OD” on my build sheet.

[joes455]

What kind of chassis dyno was that?Also using the wrong percentage to convert to eng hp.Should be more like 10%.A th400 uses up 65hp .Best is to go to the track.