gadway41

Hi Folks,

I'm hoping someone on this forum may know this answer? We have very few Automatic's on our forum, so someone here I know must Know this.

How much RWHP can a 05 Automatic Tranny handle?

Thanks much,

Jeff

Heavyg72

My numbers are in my sig....I've had it about 1 year and have had no problems.

Gene K

Alternative Auto has has been pushing the limits of the auto over the last 3 years.
They had a Vortech car at 17 psi running 10's for a couple of years.
Now they have a Whipple at 17 psi running 10's for a year or so now.

The Whipple car is stock other than the Blower/Alky Kit, 20" Street Tires, Axle Back, and Steeda Lowering Springs.
Stock Gears, Stock Converter. Stock Manifolds and CAT's.

Neither car has eaten the trans yet. I dont know if running real 20" street tires instead of DR's has something to do with it.

I think they are in the 500-520 rwhp range. I suspect the number is artificially low due to torque converter clutch slip.
The stock converter usually starts slipping before that.

That said Ford evidntly doesnt trust it with 500 bhp and Whipple evidently doesnt trust it over 7 psi (Non-FRPP Whipple HO Automatic Kit).

PS Its not hp that kills a trans but torque.

gadway41

Thanks for responding so quickly. The main reason I was asking was that I have an 05 Automatic with 11,000 miles and for the last year I've had 402/388 to the wheels no issues, within the last month I installed JDM's 425 rwhp/409 torque, no problems, Within the last week I installed JDM's 550 kit which should yield 460/ ? at the Wheel, no problems, Today I went to my local Dyno and had a couple of pulls. All I could get out of it was 416/409. I was told by JDM that the Belt driving the supercharger which they sent me was the wrong length, so that why I wasn't seeing 460. We'll on the way home from the dyno, the transmission starts slipping real bad, 3 gear barely coming in. To be more specific I think that before I put it on the Dyno, when getting on it the Tires would spin, saving the transmission, now on the Dyno, all the stress went to the transmission and now is slipping.

What do I mean by slipping? Well, before I went on the dyno the torque, and shifting, was percise and perfect, now if at about half throttle 1 & 2 are ok not the same as before, but then the engine rev's right up to 6800 rpm's(pretty scary) then I back off and if I'm lucky 3 may hook in.

Haven't had a chance to talk with JDM yet but this is why this question was asked.

thanks.

1morepart

first, nice power numbers!!!!!!i'm not an expert on auto's,but IMO you definitely need a tranny that will hold all that power.....the stock automatic wasn't meant for your numbers

gadway41

If that is the case and I'm not doubting that, why does a vendor like JDM offer these kit's without any kind of warning. I told them I wanted the Highest numbers I could get, but they are to use their judgement because they are the experts. 460 was there safe area. I'm not blaming anybody yet, just looking for others experiences.

Gene K

Did the car have some cool down time before you drove it home? If not the tranny may have been overheated especially is the converter was slipping on the dyno.

Other than that I would not be suprised if the dyno got it. They will kill a clutch in a manual as well when it never slips on the street.
I know JDM is big on tight belts butmy guess is the low numbers are from the tranny slipping on the dyno.
If the belt was to looseit would feel slower on the steet than it did in the previous tune.

PS was that 13.5:1 accurate with the previous pulley/tune? Ouch!

gadway41

I have a transmission Temp gauge and it never got over 180 degrees. So it sounds like this is what has happened, the transmission is on it's way out.

Yes that a/f is correct, I was going to stop at the HP/t but decided to put in the Dual Fuel Pumps, at least my A/f is good now, it came in around 11.5.

We'll if this is truly the issue, JDM and Saleen Speedlab will be getting a call. When we push our cars to the edge, we expect our vendor's to take care of our best interest, unless we are careless in what we are doing. I was not. I asked for safe, if I can't put the car on a dyno without it breaking, well need I say more.

Thanks for you input, it is appreciated.

sdsguy

even though you're asking to do something safely, it doesn't necessarily mean everything will hold up. to them, maybe safely meant not blowing the motor or an axle or something. everyone knows modding is at your own risk, unless it's just flagrantly a vendor issue. one reason why i would never dyno my car is because they hammer those things in pretty harshly. besides, HP numbers are kinda useless imo. times are.

gadway41

This is a risky area, but how else do you make sure the A/f is good. If I hadn't checked it the time before I wouldn't have known that I was running lean. I'm hoping we can work this out, Saleen and JDM have been good to me and that's why I will stay a customer of theirs.