FASTFATBOY

iTrader: (23)

I am about to buy a PI Vigilante converter, part# PIV 259715 for my car. It is listed as a 3600 stall. The previous owner said it flashed to 3800 in his lighter lower power car that ran 11.0.

I called Precision Industries about the converter, they told me this is the converter they would spec for my car. The guy said it should flash to 4000-4100 in my car, which is very close to where I need to be.

I was talking to a guy that has built and been around ALOT of F bodies this weekend, he told me the PI converters dont MPH well and are not very effecient.

ANyone got any experience with this?

Thanks guys.

Gray86hatch

iTrader: (83)

To gain efficency with a higher stall you need a smaller diameter.

My 8" goes 6000 and locks up 5-6% at 7000

Tim

Aaron91RS

iTrader: (8)

I have heard the MPH thing, but I don't think anyone would say they're inefficient.
There is a graph on here somewhere that lists out all the yanks and vig's and shows their efficiency's. I can't find it now though.

01ssreda4

iTrader: (96)

Converters are give and take. Its hard to have your cake and eat it too. Autos cars dont MPH that well anyway. They are kings of ETs. If you want MPH buy an M6.

Gray86hatch

iTrader: (83)

Just buy a good converter. You can get a converter these days that will lock up 2-3% and have the mPh. You just have to get it from the right person.

My exp with the PI stuff is lots of slip when the get remotly loose. Low mph due to the slip.

Tim

GregWS6&z28

iTrader: (8)

FTI or Yank would be my choice.

gsxr1k2

iTrader: (6)

I was trapping 120 with my Vig stalled around 3000. I just restalled mine through vig @ 4000 so I guess we'll see.

01ssreda4

iTrader: (96)

Are you saying vigs arent good converters?? Bc I have heard completely the opposite.....A converter that hits hard off the line looses efficiency up top, softer hit off the line gains more efficiency in higher rpms. Generally speaking of course. At what point was a converter invented that did everything perfect? Care to point me that direction??

performabuilt

iTrader: (25)

Well explained there is no one converter that can give you the best of all. each is tailored to the individual needs or compromised to suit the widest range the person needs. In computer terms its like saying I want a super fast laptop whos battery last a really long time. Or a 800 rwhp car that gets 40 mpg around town.

Gatsby

iTrader: (7)

Are there any objective measurements for whether a converter is better off the line or better up top? Is that what STR is for?

01ssreda4

iTrader: (96)

^^^My understanding is STR is one aspect of the whole converter puzzle. But very generally speaking, higher STR yields a hard hit off the line and better/tighter part throttle driving bc of more torque multiplication. Lower STR yields softer launches and looser feel but better efficiently at higher rpms. At least thats my elementary understanding of how converters work, surely there are other effecting factors.

FTICONVERTERS

iTrader: (3)

The higher the str the harder it hits and the less efficient it will be during coupling phase. Opposite for the lower. Each converter has its place. This is why we use a build sheet to custom build converters for each application to tailor the converter to the customers needs and driving style. Its all combination,combination,combination. It all has to work together----camshaft,converter,cylinder heads,gear,weight,etc.

Greg

omcar

iTrader: (10)

I have that converter and with my STOCK (lid/pulley) motor I ran a 1.57 60' and 12.02 @ 112 but who cares about mph when you are bracket racing.

Aaron91RS

iTrader: (8)

I found it!
This is a time of accl. of converters from dead stop to red line in 3rd gear with max work load applied
This graph should really go in the stickies IMO.
Anyway here's what I see looking at the graph but that doesn't mean I am right, but hopefully it will make for a good discussion.
If stock is the slowest then lower numbers on the right are better.
To me this would seem to show that the vig 3600 which is a lower stall still got there faster then the super yank 4000.
To me this means I can not only use a tighter vig converter(and tighter should be more efficient up top) but it will still get there quicker?
Am I reading that right?

Pro Stock John

iTrader: (34)

I've had two PI converters over the last 10 years, and neither was particularly efficient. The last one was in Pinkenstein. I actually swapped out a Fuddle 8" and swapped in a PI, and the car went slower both et and mph. Swapped the Fuddle back in and the car ran better. I lost 3 mph.

I'd check out Circle D, they have a good track record. I'll be trying them in Project Shizzler.

FTICONVERTERS

iTrader: (3)

The graph is a bit misleading as the higher the stall then the less time it should take to get to 6200. if i build a 5500 converter then it only has to gain 700 rpm so therefore it should take less time. Dont mean to seam grumpy or start an argument just trying to help. we have plenty of cars running in the mid 6 sec zone 1/4 mile at over 200 mph and have several LS f bodys in the mid 8's at mid 150's on drag radials as well as the world record on leaf springs nitrous powered car.

Efficiency is measured at the finish line. the difference between driveshaft rpm and engine rpm. this is affected by gear ,tire ,weight,lenght of track etc. so with that being said you basically want a converter built for your combination whether it be 4000 or 3600.

Greg

mike13

iTrader: (27)

ineffieciency is very misleading my car with a 3200 stall, 3.73's turbo motor at the top of 3rd gear has a 700rpm difference between wheel speed and crankshaft rpm. So Im thinking this is terrible. Checked some data logs of some cars that et and mph well and they are in the 500-700rpm range also.

Checked some datalogs of cars that had very little converter loss and they spent much more time trying to get to peak torque and horsepower instead of staying there. If you had a properly configured convertor that you locked up at the 1/8th or 1000ft that would be the best of both worlds.

Aaron91RS

iTrader: (8)

so then wouldn't it be more impressive that the lower 3600 vig is getting there faster then the higher 4000 stall yank?

FASTFATBOY

iTrader: (23)

Wouldnt the distance traveled have to apply here?

Paul57

I believe that would be a...Yes!