Percentage of drive train loss

[434nova]

What percentage of drive train loss do our turbobuicks have ? I have been told 15 to 18 percent loss. And will having an unlock converter make a difference in rear wheel hp numbers. Thanks

 

[psycho6cyl]

i would think a good torque converter would bring that precentage down. subscribed

 

[434nova]

Bump for the experts.

 

[bison]

Based on mass flow the power loss through the drivetrain is much less than most would think. I see about 15% typically when looking at fuel consumption and displayed power. It would be very easy to increase whp with a locked converter or a converter that is very tight. These will however slow a car down in the quarter mile because average torque available will be lower. A proper torque converter can hold the engine at or near peak power for an entire pass which results in a great potential for reduced elapsed times vs a car with a locked converter that may show 10% more power but only spends 20% of the time during a pass at that engine speed and load. Flash stall and tuning for the best elapsed time is most important.

67-68lbs/min here in the good air. With high octane I could have squeaked out another 3-4% power without adding airflow. This will translate into 132-133mph at 3600lbs

The converter in this cars flash stall at full load is 5300. It's easy to see why it will run like a champ at the drag strip even before you get there. Optimally this engine would need a ratio change around 5600rpm. Even holding to 5700 wouldn't really slow it down more than a couple hundredths.

BPE2013@hotmail.com

 

[434nova]

Thanks bison. I made 470 rwhp thru a 200r4 and 9 inch ford rear and was wondering how flywheel hp that was. It was at 4800 rpm , valve spring issues, 9 inch has 40 spline axel. I figure I was around 550 flywheel. This is with a art carr 3200 9 inch non lock up converter.

 

[Nascar83Fan]

When you ( the OP ) said there were valve spring issues, as in they were weak or worn and were not stiff enough for that build?
You would lose some power across the power band with that going on and it would lower the ability for the engine to breathe as efficiently.

You probably without the valve spring issues would of found you'd of made a tad more power at the flywheel and at the tires. If you do assume you have 15% loss, then with the 470hp at the tires you would come out to 552.94 hp at the flywheel.
You probably without the valve spring issues would of seen closer to around 570 hp if not more at the flywheel and would see closer to around 480-490hp or so at the tires with the assumed 15 % loss depending on weather conditions etc. It'd be interesting to see without the valve spring issues what you would of got on that dyno, as it would seem it sounds like that motor is probably pushing over 570 hp at flywheel and you'd get around 500 hp or so at the tires with everything working properly easily.




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[434nova]

Valve springs were dead had about 70 or 80 #s on the seat open pressure was bad to. Cam is a hydraulic billet roller 206 from weber. Motor was sitting for about 5 years and I think the springs went dead from that. All the springs had broken inners also. Motor wouldn't Rev past the 4800 rpm. I would like to see what it would make without any issues. Dynoed was also a dynoed dynamics which I heard also gives lower rwhp numbers.

 

[bison]

Valve springs were dead had about 70 or 80 #s on the seat open pressure was bad to. Cam is a hydraulic billet roller 206 from weber. Motor was sitting for about 5 years and I think the springs went dead from that. All the springs had broken inners also. Motor wouldn't Rev past the 4800 rpm. I would like to see what it would make without any issues. Dynoed was also a dynoed dynamics which I heard also gives lower rwhp numbers.

Sounds like it had the wrong springs from the time they were installed. I've picked up over 200hp with springs more than once


BPE2013@hotmail.com

 

[Red C5]

I always estimated 15-20 % depending on converter.

 

[85tr]

Sounds like it had the wrong springs from the time they were installed. I've picked up over 200hp with springs more than once


BPE2013@hotmail.com

200hp from just replacing springs ?

 

[bison]

200hp from just replacing springs ?

More than once and more than 200hp. I had one that laid over at 4400 and was a bag of poop by 5000. It wouldn't even come up on boost all the way till I changed springs. Once fixed it cranked to 5700 and I saw almost 70lbs/min. Out of the 12's and into the low 10's.


BPE2013@hotmail.com