i have my car setup now and will be running mostly n/a but also want to spray it a little thats whay i went with a bigger converter cause im running n/a most of the time ! anyways my shift point is set to 6300 but it shifts around 6500 is the the 4200 ok with an occasional nitrous pass no more than a 150 shot??????

 

On the gas it'll prolly leave pretty close to your shiftpoint!

 

To BIG.

 

Sounds to big, whats the RPM band of your cam?

 

well what if i lock out 1st gear? i mean i can always try it out of the hole right ...whats the worst that can happen window switch shuts off the gas and i hit the revlimiter ??? is that it?

 

well whats the verdict ?????????

 

my vig 4000 slips about 22% at 6500 on the bottle, and 7.5%N/A unlocked through a t400

 

so are u saying a lower stall speed would lower the slippage i dont really understand cause isnt the converter always slipping ? its just hard to understand a lower stall speed would matter that much if the converter was operating propperly please explain?

 

Just dont spray out of the hole....or send it back if you haven't installed it yet.

 

jack at precision said i was fine today even out of the hole on the gas! so i will install it and see if it will work i just dont want to sacrifice any n/a unless it is a must. i mean is there really a significant difference going with lets say a 3500 on the big end ???? jack doesnt think so!

 

yea well vicki and jack both told me that vigs were good nitrous converters, and mine slips 22% at 6500 and even more at rpms blowe 6500

 

Sure they are (if there triple disk lock up converters are used)

"Red96Z"
My PI is rated at 3200 and the actual flash stall on my stroker is 4400-4500rpm (supposedly 3600-3800 flash on a stock LT1). It's 93.5% efficient at 6300 and 95% at 6700. So, on a 350 cubed engine look for something like 95% at 6300rpm. My flash on a 150 shot is 5000 rpms. This is the loosest PI verter I would use on built engine with N2O. If going Yank go no further then 3600SS if your using N2O. I see some guys go 4000SS but thats on a more stocker engine combo with a 150 shot only.

 

SO ARE U SAYING IT WONT WORK OR IT WILL.... JUST WONT BE AS EFFICIENT AS IF I HAD A TIGHTER CONVERTER. IN TERMS FOR ME TO BETTER UNDERSTAND.. WILL THE ET GAIN BE SIGNIFICANT??? WITH A TIGHTER CONVERTER?

 

Are saying that you don't believe my convetrer is that ineffecient? Mine is a th400 spragless. Vicki said they use the spragless converters on cars with transbrakes and nitrous.

 

I use Flash stall as a gage....gives me an idea how much extension a converter will most likely have (that's not set in stone). Converter extension is what your really worried about. To much and you'll loose efficiency in the upper rpm's, to little and you'll more than likely not have enough rpm at your extension point (rpm you drop down to after gear change), and be to low in the rpm band. The PI 3200 I use works great for Nitrous on my stroker but I shift at 6950rpm's and my extension (on Nitrous) drops down to 5700 rpms. If I were to shift my engine at say 5700rpm's my extension would = my shift rpm which is real bad for efficiency. My converter (off Nitrous) has a shift extension of 5200, which is a little low. I have heard from many racers over the years that "NA" you want between 1000 to 1400 rpms extension drop on the shifts for the best power band (this depends on engine power band and converter efficiencies at those rpms). However, some of these converters will get real loose when hit by Nitrous and some won't. This is where peoples experience with a particular converter comes in handy. This is why I recommend no PI stall above 3200 with Nitrous. The "3200" converter already will more than likely flash to 4K for your combo, for good launches. And have a tight enough extension to hold maybe up to a 250 shot of juice. As you can already tell there's going to be a trade off in Flash stall and extension "NA" vs. "N20". Now, for Yank converters I recommend the SS3600 which will have about the same characteristics as the PI 3200. I have no experience with Fuddle so, I can't make a recommendation on their verters.

"n20fed"
I only have experience with PI's 9 1/2 inch lock up converters. But if your seeing what I have read about your problem, then yes. Your extension is too high killing your efficiency. The "triple" lock up converters only apply to Turbo or Big Nitrous shot. These guys you a manual lock up switch, usually in second gear and above. Where your mid range torque is so high, that you don't need converter extension to help you accelerate. I would recommend either having your converter re-stalled lower "say 500 rpm's," which is supposedly = 1000rpms less of extension. Or change to a different line of converter with something more proven to hold horse power. You have a turbo 400! So, their are a ton of great companies. Coan, Continental are just a few...