How does everyone check the converter stall safely ??
thanks jjj

Racepak

Or a playback tach......

I always felt the most useful stall was the “fall back RPM” after the 1 -2 shift. I also think that stalling it in the pits against the trans brake was the most useless and unsafe. One of the two tests represents real conditions. Describing that to a converter supplier and their ability to deliver is critical.

quote:

Originally posted by jjj:
How does everyone check the converter stall safely ??
thanks jjj

What brand? Spragless you can test it on the transmission brake.

Sprag converter you can as well, it's hard on the one way clutch though, so make it good to do it only once.

quote:

Originally posted by adv ET 266:
I always felt the most useful stall was the “fall back RPM” after the 1 -2 shift. I also think that stalling it in the pits against the trans brake was the most useless and unsafe. One of the two tests represents real conditions. Describing that to a converter supplier and their ability to deliver is critical.

Agree on all points

If you want to check the stall, you remove the 2-step chip, put it in gear on the brake and then mat the pedal. I agree with others, not the best way.

Flash stall is maximum rpm at launch or fall back as another stated after 1-2 shift are better to use.

If you don’t have data acquisition or a playback tack, consider using a cell phone mount to record the tach during the run.

Nothing much more dangerous than matting it in the pits and should be avoided.

At the very least if you do it that way car needs to be on jack stands just to be safer

I routinely checked my "cruise rpm" for S/C and even when using a SLE but always had my car on jacks and was sitting in it.

I did have a recall tach after installing a large one and recorded most runs and could quickly replay the last run using it.

Adding a grid was a big plus as it recorded every run and the rpm graph was very good and more accurate than the tach.

Pulling the chip and checking stall usually shows 100-200 rpm less than the flash and fall back, unless the converter is setup for nitrous, then you can get one that will give you a false high reading. I will say this, a great starting point with a new converter, is to shift it 800 rpm above whatever the converter stalls without a chip.

Grid for me. I download my runs and overlay them to check for consistency. Best tool (price wise) out there to find a problem in my opinion.

Observed stall is often confused with stall.

These are all observed stall

6632 at hit and 6818 at shift

Most know this but for the youngsters trying to soak up any knowledge to help their racing.

Stall is whatever you're told it is, when you're sold any given converter.

Observed stall is what any given converter stalls, once installed,,observeably. Stall is determined by power. This is why observed stall can also be used an onboard dyno.

+400 rpm's stall is 100hp. -400 rpm's of stall is -100hp.

It's not 100% accurate, but pretty accurate.

IMO a data logger is the best (and safest) way to check converter stall. These systems are quite affordable these days and can be very beneficial to the users, a wise investment. Add a driveshaft sensor and you can then verify converter slippage at the stripe.

Data acquisition graphs can help a convertor company determine how best to build what you want. Very important when doing a re-stall of a new/ used convertor imho.

quote:

Originally posted by Fabman:
IMO a data logger is the best (and safest) way to check converter stall. These systems are quite affordable these days and can be very beneficial to the users, a wise investment. Add a driveshaft sensor and you can then v erify converter slippage at the stripe.

Are DS sensors legal in all bracket classes? I just added an FT 600 to my FB/NOBOX car for data acquisition.

Thank you everyone for the information. jjj

quote:

Are DS sensors legal in all bracket classes? .

Section 4A, page 7 Super Pro, Pro, Sportsman ELECTRICAL: 8

P. 82 of 2023 NHRA Rules Book PDF version

INSTRUMENTS

One tachometer allowed. Driveshaft sensor may be connected
to either the tachometer OR the data recorder, but not both.
Must be one single wire, with no splices, and easily traceable.

This message has been edited. Last edited by: markemark,

quote:

Originally posted by FastLane:I just added an FT 600 to my FB/NOBOX car for data acquisition.

Excellent all in one ECU that puts everything at your fingertips. Very easy to move into EFI with this.
FT600

drop back is true stall

Rusty 100% True