Calculating HP loss due to converter slip ?

[Mike T]

This PL snap shot was with a Hughes converter on the dyno. PL shows 26 % slip @ 443 peak HP. Is there a formula to calculate what HP should have been with a more efficient converter? BTW I now have a PTC 9.5 17 blade.

 

[No disintegrations]

I'll shoot from the hip and say that since the input is going 26% slower it's turning about 4000rpm. If you had good coupling you'd have almost 26% more power. So about 110 more to the wheels. 550 rwhp

 

[bison]

Your data looks flawed. Post gear ratio and approximate mph.


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[bison]

I'll shoot from the hip and say that since the input is going 26% slower it's turning about 4000rpm. If you had good coupling you'd have almost 26% more power. So about 110 more to the wheels. 550 rwhp

No way. It would take almost double the engine speed.


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[Mike T]

Your data looks flawed. Post gear ratio and approximate mph.


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93 MPH, stock trans and 3.42 rear. Tires are close to stock height. Values for the PL are what Bob has posted.

 

[TurboDave]

What 3rd gear cs factor are you using? Is your converter capable of locking?

 

[Mike T]

What 3rd gear cs factor are you using? Is your converter capable of locking?

Value of 46.40 for 3rd. Hughes converter was a lock-up now I have the PTC N/L. These are logs from a while back, motor is out now for a few changes.

 

[Mike T]

Tire is 25 .5 tall

 

[bison]

Mph from Dyno sheet?


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[Mike T]

Mph from Dyno sheet?


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I'm not on the home computer and I can't refer you to the link on my phone. The dyno chart is on a thread called 443 HP on pump gas only or something like that. I believe the MPH is what I used to synchronise them.

 

[bison]

I'm not on the home computer and I can't refer you to the link on my phone. The dyno chart is on a thread called 443 HP on pump gas only or something like that. I believe the MHP is what I used to synchronise them.

You need accurate mph (or driveshaft speed) to be able to calculate slip. Displayed values can be wrong because the vehicle speed sensor has lag


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[Mike T]

You need accurate mph (or driveshaft speed) to be able to calculate slip. Displayed values can be wrong because the vehicle speed sensor has lag


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Ok...I found the dyno chart and using the tps on the PL as a marker they back each other up. Dyno showed throttle was cut prior to 98 MPH and PL shows TPS was closing at 94 MPH. Does this help?

 

[TurboDave]

Value of 46.40 for 3rd. Hughes converter was a lock-up now I have the PTC N/L. These are logs from a while back, motor is out now for a few changes.

That's the value on mine, but I have the luxury of a lockup converter that has NO slip when locked, so I lock it manually and keep adjusting the value until I see zero CS.

 

[Mike T]

That's the value on mine, but I have the luxury of a lockup converter that has NO slip when locked, so I lock it manually and keep adjusting the value until I see zero CS.

Thanks for confirming that Dave. How do you feel about the overall accuracy of the TC slip feature in the PL?

 

[Mike T]

I'll shoot from the hip and say that since the input is going 26% slower it's turning about 4000rpm. If you had good coupling you'd have almost 26% more power. So about 110 more to the wheels. 550 rwhp

Thank you for your reply. Before I posted the question here I searched other forums that suggested using HP x slip . This produced a number similar to yours. Kind of felt that method was off.

 

[TurboDave]

Thanks for confirming that Dave. How do you feel about the overall accuracy of the TC slip feature in the PL?

Good question. Wish I had a good answer. I've on occasions seen some pretty astonishing numbers, I don't know.


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[Mike T]

I'm seeing 50% then it will slowly go down as it couples, 24% was the best under power on the dyno.

 

[TurboTnZ06]

I don't think you can. On my old LU 9/11, it'd blow right to 6200 and stay there. Well past peak tq/hp. Now my PTC 9.5 NLU, it couples HARD flashing 5500 down to 5200 in 3rd with my dual fed 3rd billet ninja trans. RPM and slip is lost hp, have to get it back down in the power band to find the most power and then put it down.

 

[Mike T]

I don't think you can.

That really surprises me if it's true. You would think known HP x at least a portion of the slip would be a start?? Maybe too many variables.

I have seen post saying 50 RWHP is not uncommon when replacing a inefficient converter with a 9.5 PTC.

 

[Pronto]

Fyi, the nl trans will mess up the pl slip since it's not using the 3/4 signal. I tried the 2ND gear numbers and the % made a little more sense. I think it's still not accurate .