JDMC5

iTrader: (3)

This is my 99 Trans Am with mods in my signature. The top graph is with the 4" cutout open and bottom one closed. I later swapped to a set of 1 7/8" headers and the car made 435hp and about the same torque as with the 1 3/4" headers. What do you guys think? The cam is a 228/230 .629/.604 112+2

Although not shown in the graph its also worth mentioning that the horsepower stayed flat from the peak at 6700rpm - 7000.

sillysspeed

iTrader: (21)

Nice numbers. How much timing did you put into it with the e85?

HCI2000SS

iTrader: (2)

Will be interesting to see how it reacts with the 4.30 gear

sillysspeed

iTrader: (21)

Yea I know this is the dyno section but if he's thinking of running at the track at all it wouldn't be a bad idea to run it first. It might run out of gear at the top of the 1/4 with 4.30 gears. I have 4.10's and I'm crossing @72xx with 28" tires. We always plan on going faster so that number is only going to increase.

HCI2000SS

iTrader: (2)

He's actually a buddy of mine so I kind of know his future plans and goals.

sillysspeed

iTrader: (21)

I gotcha just a suggestion. See if he can post up how much timing the car liked with the e85. Curious if it made any more power past the limits of 93 octane

HCI2000SS

iTrader: (2)

I'm sure he will chime in soon, but I wanna say he said it's at 28 degrees on the E85, and would only take 25 degrees on 93. I might be a little off but thought i remember hearing that

JDMC5

iTrader: (3)

hey sorry for the delayed response. Rod you are correct 28-29. The engine seemed to respond to the extra degree of timing with the bigger headers. Gains were minimal though. This combo is relatively insensitive to afr as well. Speaking in gasoline terms for afr, it was between 11.5 and 12.7 it made about the same power. Never dyno'd on 93 but i couldn't run timing past 25 degrees or it would ping.

I ran the car with the current setup already, the car is definitely under geared with the 4L80e and my weak torque curve.....and my converter made to handle nitrous. Too much time slipping the converter and not using much of 3rd gear make the car a dog. I've done the math and locking my converter with 26" tire I should be running 6300 rpm through the traps. My car only traps 115 now. Also i can always put a 28" tire on it worst case.

I also want to point out how much my curve is shifted. The power is best 5500-7000, needs to rev = gears

AINT SKEERED

iTrader: (2)

My nitrous converter with 4.10 gears liked 26"tires for the gear ratio on motor. .1 quicker and .05 better 60ft.

Just swapped to a 8"fti motor converter that flashes to 5300 and 6140 on transbrake. Best ever with 4600 nitrous converter was 11.21@122 with a 1.60 60 ft. In 0 da
Best with the new 8" fti is 1.52 60ft. 11.27 @118.8 in 2000 above da
That's on a no prep track. It has 10s in the heat .3700 race weight and 460rwhp with the other converter.
Do the gear swap. On motor run 26s on nitrous go with 28s.

JDMC5

iTrader: (3)

Well got the 9" in. Car feels faster. Did exactly what i was hoping for. Completely rips though the gears. I don't feel any power loss at all, just the effects from the gear. 60 ft will definitely improve. Also, 3rd gear is usable. I'm expecting significant gains. I'll have to scan to get hard data but most likely 3 tenths. We shall see.