Th400, 800 hp, 2.75 gears and a 3500 stall
05-08-2006, 12:02 PM
#1
Th400, 800 hp, 2.75 gears and a 3500 stall Here is my issue. I have a Vigilante 3000 converter in my car with a th400. I drive this car a lot. The 3000 is actually more of a 3500 and will stall to 4000 rpms on the trans brake with 5psi of boost. I currently have 3.5 gears and am getting some 2.75 gears installed to add some more street manners. It's not bad to drive around now except at 75mph i'm turning 3500 rpms and would like to bring that down. I'm worried about the tranny temps though with the stall being this loose. I will be cruising 75mph at 2800 after the new gears. I don't have a tranny gage installed yet, but I do have a 15"x10"x0.75" tranny cooler and will probably add a fan to the front of that.
When we were testing the converter it was basically 1:1 over 5500 rpms. At 6500 rpms it was calculated at 143mph, the logs showed 141 mph. Shift extention is at 5300 rpms on the 2-3 shift at 6500 rpms. Cruising around town in 3rd at 45-50mph i'm at 2200 rpms.
How much worse is the stall going to be on the 2.75 gears? I'm only at 10 psi of boost right now and will soon up it to 15psi. I figure at 15psi it will add another 150 hp and push me to around 800 crank hp.
I would like to avoid having 2 weeks of down time on the car waiting for my converter to come back. I'm a little upset that vig didn't make the converter to the stall that was requested.
If I have to pull this converter out I'm thinking of having them tighten it way up to 2600-2800. I'm also going to give them a call to find out what they think about the gearing selection and this converter.
2.75's will make racing liter bikes on the highway more fun too
2nd gear will be good to 120 mph.
When we were testing the converter it was basically 1:1 over 5500 rpms. At 6500 rpms it was calculated at 143mph, the logs showed 141 mph. Shift extention is at 5300 rpms on the 2-3 shift at 6500 rpms. Cruising around town in 3rd at 45-50mph i'm at 2200 rpms.
How much worse is the stall going to be on the 2.75 gears? I'm only at 10 psi of boost right now and will soon up it to 15psi. I figure at 15psi it will add another 150 hp and push me to around 800 crank hp.
I would like to avoid having 2 weeks of down time on the car waiting for my converter to come back. I'm a little upset that vig didn't make the converter to the stall that was requested.
If I have to pull this converter out I'm thinking of having them tighten it way up to 2600-2800. I'm also going to give them a call to find out what they think about the gearing selection and this converter.
2.75's will make racing liter bikes on the highway more fun too
2nd gear will be good to 120 mph. 
05-08-2006, 12:25 PM
#2
Just talked to vicki at precision. Decribed what my current setup was doing and what changes i'm making and she is goning to have a converter made for me that is 2 steps tighter, she said 1 step is 400-500 rpms. She was suprised that my converter was as loose as it was. It's costing me 225 + 20 shipping to have them build me the new converter and ship it to me and then return the old one for credit.
