Well, I just swapped over to a 750 Speed Demon carb and a Victor Jr. intake (rest of setup in sig). Now when I have my 700R4 in first, if I nail it doing about 15 MPH, the car absolutely hauls ***. I am thrown back in the seat and the motor revs up fast. It feels a lot faster than before my swap. This is without wheel spin by the way. As soon as I shift to second at about 6300 RPM, the car doesn't feel anywhere near as fast as it did with the old setup. Now why would the new setup be faster in first than the old setup, yet slower in second???? Any ideas?? Thanks.

 

Is the tranny slipping, perhaps? The RPMs would stay relatively high but the car won't go anywhere.

Other than that- is it a stumble and then recovers or is it a long lay down that it doesn't recover from quickly (or at all)?

 

you dont have any wheel spin nailing it in first with 3.73s?

I go half throttle at 60 MPH and im sideways with the 3.73s and a 300 horsepower tpi motor. what kinda tires you running?

Some things to check are timing and jetting. if its too lean or the timing is off then it will be a dog under serious load, which you dont really have in 1st gear because of that steep gearing.

with small street tires you should be all over the road with that combo, anywhere near wot.

 

This was with ET Street Slicks. Also, my 3.73 isn't in quite yet, I'm still on the 3.42 stock rear end. I did a few more runs, and the more that I think about it, first gear did feel faster with the old manifold. I think I need to ditch the Victor Jr. and go back to the Performer RPM Air Gap. Thanks for the replies.

 

your kidding, i hope.

 

<b>I go half throttle at 60 MPH and im sideways with the 3.73s and a 300 horsepower tpi motor. </b>

Why do you say that? hell my friends Goodwrench 350 pushing 240~ can send his car sideways. it doesnt take much on street tires!

now my 500 horse blower motor cant even spin its tires from a dead stop standing on the brakes because its only got a 2.77 gear and a th350 with 2400 stall.

its not about how much power your motor makes, even a 90 horsepower 4cylinder can break the tires loose at 70+MPH with the right gearing and small enough tires. my little mazda with its stock 6 cylinder can do it too.

 

i pity you

 

Which one are we pitying? The one with a lack of power, or the one with a lack of traction?

I know that with my RE730's that I cant spin mine if I start above a ~10 mph roll. I dont know how much power I am making, but I ran dead even with a 95ish z28 with headers, gears, chip, and flowmaster catback the other day. If I would have realized he was going to race and launced properly I think I could have nosed ahead. I also know that I can outrun a 89 Iroc with light mods by about a car. Once I get my new heads and intake on it should make a big difference though.

Ben

 

Riiiiight. Well, unless the roads are wet. Can't spin with 2.77s? I assume they are ET streets?

 

to the origional question. One thinng answers this quite well: Crappy gear spread. The 700-R4 has a really low first gear (3.08). Little too low IMHO. You pay for that when you go to second gear (1.63), because of the large difference in gear ratios. Since there is a difference in ratios, there will also be a difference in the force at teh tires so there is less acceleration, and less force on you. You can definatly feel this difference when it shifts(i sure can), which also probably puts you in the lower part of your power band, and can especially cause problems if you have a low end bog like i do.

 

<b>Can't spin with 2.77s? I assume they are ET streets?</b>

Actually they are 275/60/R15 tires, or 29" tall.

that makes my 2.77's more like 2.32's with a standard 26" tall tire.

now do the math, 2.32 X 2.5(th350) = roughly 5.5:1 gearing. lets use my 400+ Ft. Lbs of torque coming out of the blower motor at that low flash rpm (1700~) to work it out....

380Lbs/Ft X 5.5 = 2090~ish minus frictional losses...


Now take a modified TPI motor, with stall and gears. at 2500~ RPM making 300Lbs/Ft.
26" tall tires with 3.73 gearing and 3.07:1 transmission gives us...

(3.73 X 3.07) X 300 = 3435 Lbs/Ft of torque.

So though my blower motor makes almost double the power, it still only puts down about half the torque to the wheels as my TPI motor.

This is why my power robbed TPI can break the tires loose at 60+ MPH, but my 500 horse blower motor cant even from a dead stop.

and for the record, my 6 cylinder has 4.54 gears and a 5 speed so do the math with only 200 Lbs/Ft thats still about even with the 355 TPI.

 

my tires don't spin and i have 2.73's


lmfao but i have 3.42's just waiting for the sumemr

 

king i think ur leaving out some valuable info such as traction mods on that car, my 73 nova with a 2.73 posi and 275 60 15 bfg radial ta's will light em up all day...but it has air shocks and some rather old leaf springs in the rear

 

hrm, i pity the lack of traction, it's just sad

 

You don't even wanna know about lack of traction. I'm king of it here. On a set of Sigma Supreme HP's (and there's certainly nothing supreme OR High Performance about them...).....I yanked the worst 60' possibly in history!

The car is capable of running 14.29 at 100, with a sloppy 60' of only 2.345

What it ran on the Sigmas was 15.1 at 93, with a 2.78 60'. The reason for the ****-poor trap speed is I figured I trashed the run already, so I might as well go easy on it now.

And this is with a 150,000 mile slipping tranny and a motor that still manages to put around 280 rwhp through it.

As far as driving normally with these tires, it'll kick sideways at WOT at about 30-40 mph and usually spin most of second gear. But past that it won't without rain. This is with a 4.10 POSI rear end btw.