glide powertrain loss

[stony]

I have heard some guesstimates, just wondering if anyone has "REAL" numbers on how much HP is lost to turning a power glide vs a manual tranny.

 

For example if i were making 600 at the wheels with a power glide how much would it might be if i was running a 5 speed?

 

The reason i ask is i was under the impression a glide was more efficient then a manual. But now im hearing i could be loosing as much as 100HP. The reason this concerns me is if my motor was built to handle say 800 and i try to get 750 with a glide i would actually be pushing 850 and thats way beyond what the motor or i can handle :>

 

Thanks

[letitsnow]

Motors don't have strict power ratings like that, if your builder told you 800hp it's not like it'll live forever at 799 but grenade instantly at 801. You're probably pretty safe at 850.

 

But as to your question, AFAIK the glide is more efficient than a th400 but I just can't see it being more efficient than a 5spd with a clutch. The torque converter is what causes a lot of the loss, there will always be slip. A torqu converter works similar to having two box fans facing each other, one's plugged in and the other isn't. The air from the one that's on will tun the blade of the other one, it won't spin up as fast and once it's spun up it still won't turn at the same speed. That's where the loss comes from.

 

I don't have any numbers to back this up though, just some theory. I've heard that 20-25% loss is to be expected from a big stalled auto.

[stony]

I was just using the HP numbers as an example.

 

My motor will literally last forever... well as forever as race engine go :>

in the 600-650 range. But get into the 750-800 range and it gets pretty dicey.

 

My goal was 600-650 if i got more i would be happy. So with your estimation of 25% that's a 150 HP loss. My motor is putting out 750 at the crank already and we only ran maybe 7 runs across the dyno.

 

With that said anyone that has tuned a HI end FI motor with an aftermarket EMS will know that 7 runs gets a very rough tune. oh yea the motor is still basically still in its "breakin period":roll:

 

I'm guessing we will see 650 at the wheels at 22PSI with just fine tuning the fuel and getting aggressive with the timing. my max timing right now is 24 degrees!!!

 

I know I'm digressing a bit but i just cant believe the difference a EMS over a ROM tune can do. This same motor at 27 PSI only made 610 HP with a rom tune on teh stock computer right now with the power train loss (if i had it connected to the same tranny) its already well into the 700's

 

Damn i cant wait to get this thing to the track.

[dr_hunt]

Well, the 406 dyno'd at 690HP, I was able to net 600 to the wheels based on mph calculations the last time out. That is about as real world as I can get with glide, that's about 13%. Art Carr tells me that their converter will loose between 9 and 10%.

[Scottie-GNZ]

I would not worry about or try to figure out "power loss" of an auto tranny or one vs another or auto vs manual. Focus on the converter and having the most efficient converter you can get and understand there is a direct relationship between having minimum slip and a high enough stall to launch hard. If you plan on using a t-brake and nitrous, then it is easy as you just need to get a faily tight converter and spray on the brake. Best of both worlds.

 

Perfect example of this is that 1st-gen, backhalved, 2FZ-powered Probe that runs 8s with a relatively stock engine with cams. He runs a 2800-2900 stall, sprays it on the brake and leaves at 7000 with 30psi boost......1.24s and mid-8s.

 

Regardless of what you hear about power loss from an auto tranny, a big-HP turbo car will always be quicker than a manual because of how the auto tranny helps the turbo engine under load.

[jgkurz]

I would not worry about or try to figure out "power loss" of an auto tranny or one vs another or auto vs manual. Focus on the converter and having the most efficient converter you can get and understand there is a direct relationship between having minimum slip and a high enough stall to launch hard. If you plan on using a t-brake and nitrous, then it is easy as you just need to get a faily tight converter and spray on the brake. Best of both worlds.

 

Perfect example of this is that 1st-gen, backhalved, 2FZ-powered Probe that runs 8s with a relatively stock engine with cams. He runs a 2800-2900 stall, sprays it on the brake and leaves at 7000 with 30psi boost......1.24s and mid-8s.

 

Regardless of what you hear about power loss from an auto tranny, a big-HP turbo car will always be quicker than a manual because of how the auto tranny helps the turbo engine under load.

 

Scottie, I agree with you but I've always wondered if you speed shifted (kept the gas pedal matted while shifting) if you could mitigate the advantage of an automatic. That method is an old muscle car way and it's HARD on parts but it might gain you a tenth if you can do it right. I've been tempted to try it but I always chicken out.

[stony]

I would not worry about or try to figure out "power loss" of an auto tranny or one vs another or auto vs manual. Focus on the converter and having the most efficient converter you can get and understand there is a direct relationship between having minimum slip and a high enough stall to launch hard. If you plan on using a t-brake and nitrous, then it is easy as you just need to get a faily tight converter and spray on the brake. Best of both worlds.

 

Perfect example of this is that 1st-gen, backhalved, 2FZ-powered Probe that runs 8s with a relatively stock engine with cams. He runs a 2800-2900 stall, sprays it on the brake and leaves at 7000 with 30psi boost......1.24s and mid-8s.

 

Regardless of what you hear about power loss from an auto tranny, a big-HP turbo car will always be quicker than a manual because of how the auto tranny helps the turbo engine under load.

 

Scottie I understand 100%

 

The only reason I was looking for a power loss figure is to know when I’m getting near my goal HP at the crank. I wanted to stay under a certain HP number for reliability sake. And if a glide takes another 100 HP to turn it vs. a manual I need to take that into consideration.

 

 

Oh yea BTW what the hell is up with ATI and there v-8 on the brain mentality.

 

They would not build a converter to my request but did say they would restall it for free if it was wrong. So I got a converter with a 4000 stall ( iwill not be using NOS). My dyno chart shows very clearly where my peak torque is at yet they won’t restall till I get numbers from the track. The combo I have is a very common one and well I should have gotten a 6K stall to begin with… on a positive note it is making tuning a lot easier:>

[stony]

Scottie, I agree with you but I've always wondered if you speed shifted (kept the gas pedal matted while shifting) if you could mitigate the advantage of an automatic. That method is an old muscle car way and it's HARD on parts but it might gain you a tenth if you can do it right. I've been tempted to try it but I always chicken out.

 

The fact is.... you as a human being will never be able to shift as fast with your arm as an auto can shift.

[stony]

Another thing that kind of sux is im using the ATI rb to glide adapter and guess what only the ATI converter works with it.

 

 

I guess now that I have a converter that fits I could send it to someone like art car or Neil chance and have another built using it as an example but oh well life is what it is

[dr_hunt]

The only manual trans to use is a lenco, best of both worlds.

[woldson]

In the 1/4 mile useing turbos is the only way to go. Turbos love long gears and with a auto the turbos will stay boosted all the way down the track after you get moveing. My friend steve with his tt v8 corbra (factory five) always was fighting the shift very heavy duty manuel. Finally put in the auto and the 1/4 instantly was a second shorter! You the bov never fires untill the end of the track! Fun in driveing or track not so much.

[BirdmanZ]

The only manual trans to use is a lenco, best of both worlds.

 

Now that would be something to see in a Z!