Slyno96

we've got a 408 stroker thats not mph right. It made 502 rwhp all motor and 684rwhp on nitrous. It was in a six speed car with stock gears and stock suspension and it trapped consistant 120s spinning like crazy. Now we put it in a t/a w/ full aftermarket suspension front to back and a th400 and 12bolt(3:73) and its only trapping 112-115. What could be the issue? the 400 and rearend??? any suggestions would be great!

GOaT Cheese

Did you check the thrust angle and wheel alignment. I have personally witnessed knocking 7 tenths (3/4 of a sec.) off of a '67 Big block Chevelle by aligning the wheels only! We did nothing else, only the alignment. He also gained almost 10 mph.

1QuickT-A

iTrader: (12)

The only reason it was trapping in the 120's was because it was "spinning like crazy" and it had a 6spd behind it.

Now its probably hooking alot better so naturally the trap speed is gonna be a good bit lower than when it was spinning the tires. And on top of that you now have an automatic behind it so its not gonna mph as high anyways.

68maro

dude you have something up with 502 at the wheels it should be in the mid 120's easily

GOaT Cheese

Huh? I understand the increased parasitic drag from an auto versus an M6, but please explain your tire spin theory. How does hooking slow you down? That hasn't been my experience.

SiL3NtXWS6

iTrader: (17)

If you aren't trapping mid-high 120's, there is something wrong.

T6Rocket

Some manual transmission cars can run a higher speed on a pass with severe wheelspin. The wheelspin causes you to hit the rev limit, and you shift to the next gear sooner, all the way down the track. The ET ends up horrible, but the MPH is a "little" higher.

Al

TeEnAgE pHeNoM

iTrader: (6)

True spinning increases MPH. Something is definitely wrong. My stock cube motor trapped 117.3 in really humid weather(Mississippi)

Old Geezer

iTrader: (3)

You could be "driving thru" the converter.
Datalog the runs, and look at the engine rpm. Then, do a calc to see what converter slip % is.

Also, look at rpm drop between shifts.. Could tell you even more about converter performance/match.

What is the stated stall vs the actual?

A high slip %, and/or a very low drop on the shifts, too much stall, indicates a poor match to the engine performance curve.

sbcgenII

iTrader: (1)

I was looking at that trans and conveter before scott bought it for his car. I saw how much that it got beat on and was a brand i never heard of before and when i looked them up couldnt find anything good about the company so i would say you are blowing threw that thing and need to pick up a yank or ati, you also might want to get a stock stall and put it in and make sure it still is making the power it should. What rpm was he going threw the traps if you figure out your slippage you will know if the one in there now is junk or not.

Black Sunshine/ 00SS

iTrader: (1)

If the motor is running good, it's probably the convertor. Get one speced for your use. My 402, T-400, 12 bolt (also 3:73), DR, traps 125.6, with a best of 127, not much difference in MPH on or off the transbrake. This is on motor, with a convertor speced out for nitrous.

GOaT Cheese

I've been drag racing for some time now, both auto and manual cars, some hook, some don't, but I've never had faster trap speeds with the cars when they are spinning versus when they are not. As the tires are spinning all you are doing is consuming realestate before the power of the engine can actually accelerate the car. Then instead of running 1320 feet at full power acceleration, now you only have 1150 feet to gain top speed. ( or whatever the distance deduction may be before optimal traction occurs).

Old Geezer

iTrader: (3)

be a GER? If so, that HAS to be the $HITTIEST piece of junk, I've ever had the displeasure of working with.

Like I posted, B4.... Get a datalog and see WTF is up w/ the rpms...Simple test/sound results.

1QuickT-A

iTrader: (12)

Well I have been racing for a little while myself and I have been around everything from street cars to promodified cars and I thought everyone knew that alot of the time you will MPH higher with a worse 60ft time.

Lets say you compare 2 time slips and on 1 slip you went 12.503@114.6 with a 1.65 short time and on another you went 12.58@115.8 with a 1.74 short time then you will see what I'm saying..