I sent my Vigilante 2800 stall off to P.I. for a restall to 4000 rpm in the hopes of getting off the line better and improving my abysmal 60 foots (2.xx) with my T56.

Just wondering about your leave technigues. Are you foot braking it or flooring it from idle, some other RPM?

Thanks,
Dave

 

Th400 with 2 different converters and 2 different pairs of turbos over the last few years....

First converter was a PTC custom built unit that i wanted 4000 stall. It stalled at 5400 with boost...I shift at 5800-6K most of the time. But this didnt hurt the car and actually helped I think. The high rpm flash at first hit allowed turbos to spool quickly. I ran twin MP T60 T4's with .68 a/rs. Lightning quick spool, very hard to drive on the street with such a high stall.

I would brake stall as high as I could go trying to build boost but never did. Pushed through brakes. Alot of guys seem to have this problem pushing thru brakes but some local guys were seeing 3-5psi on footbrake which makes me think my tune was off and it likely was. I never tried tuning for boosting off footbrake. But leaving off brake stall and no boost still netted decent 60's since turbos came online at 20-30ft out 1.49 was best, with most in the high 1.5-low 1.6 range depending on boost level.

What did seem to help was to throw tranny into neutral at the staging beams. Rev it real high with a quick throttle stab to build alot of vacuum since my cam is large and didnt have alot of vacuum at idle. With throttle high and vacuum raised up, I'd quickly smash down on the brake pedal and it gave abit more clamping force. I once built 1-2 psi off the brake my last run of the year but spun when I left. Would have been a real good pass.

Sent converter back over winter and got it stalled to 4200 now. Same turbos, 60's got alittle worse. Just werent lighting up as fast now. Switched to T70's same .68 a/r thinking the compressor was a better fit efficiency wise for my motor and it slowed down more. Too long to spool and had to run extra boost to match my traps with the old combo.

Now I have same turbos but with .96 a/r's for new combination... much larger heads and cam/ported intake to pull more rpms to get more use out of the turbos. Same converter. Hope to have it running within next few weeks and within a month or 2 have it ready/tuned for first track day.

 

Jack from Precision Industries/Vigilante called me last Friday to say the converter looks good inside (it should, I bet there's less than a 1,000 miles on that thing. Maybe more like 300) so they're restalling it to 3,800 which, he said, should 'flash' to 4,000 rpm. It's on it's way to me. May be here this coming Tuesday.