Go
New
Find
Notify
Tools
Reply
  
Parasitic Loss
 Login/Join
 
DRR Pro
Picture of chasracer
posted
Powerglide, 8" Converter and 9" rear with 31x14 tire - would a loss of 10% HP be a reasonable assumption?
 
Posts: 1135 | Location: The problem is not the problem. The problem is your attitude about the problem. Savvy?” ~~ Captain Jack Sparrow ~~ | Registered: August 21, 2000Reply With QuoteReport This Post
DRR Top Comp
posted Hide Post
Take for an example any car that runs better than it should, meaning it's optimized. To calculate the standard percentage.

Wallace has a calculator that figures flexplate HP and back tire separately according to inputs of weight and et.

Calculate any other similar car for tolerances in comparison to the standard.
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Trophy
Picture of Rick!
posted Hide Post
10% is probably a bit light.
I've used 15% since auto mechanics in vo-tech and it's pretty close.
A ford 9" is about 94-95% efficient due to its high offset of pinion to ring gear.
The PG from the input shaft rearward is probably around 94-97% efficient in high gear at best due to the two sets of bevel gears in the planetary.
The 8" convertor is the wild card - this would need to be estimated by the temp increase in the oil from start to finish of the run.
If you go by slip %, then it could be about 8% slip, or 92% efficient.
Now multiply them all together:
Optimistically, .95 x .97 x .92 = 85% efficient.
YMMV
 
Posts: 81 | Location: behind this screen | Registered: July 30, 2015Reply With QuoteReport This Post
DRR Top Comp
posted Hide Post
11%

 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Sportsman
posted Hide Post
Which brings in a question from me. When building up a powerglide, what do you guys do to reduce parasitic drag? I have Carl's book and have read it, but do you guys use the practices that he's written?
 
Posts: 540 | Location: central Ar | Registered: June 21, 2002Reply With QuoteReport This Post
DRR Pro
Picture of chasracer
posted Hide Post
I think there are a few things you can do that help, whether they are truly measurable might be questionable.

I always mod the back of the pump for a torrington bearing instead of the normal bushing. And I think the roller bearing rear support is another drag reducing trick. I also remember reading something about putting pieces of 0-ring rubber in the main clutch pack? - I'm probably off by a mile here but maybe somebody else can shed some light on that one.
 
Posts: 1135 | Location: The problem is not the problem. The problem is your attitude about the problem. Savvy?” ~~ Captain Jack Sparrow ~~ | Registered: August 21, 2000Reply With QuoteReport This Post
DRR Sportsman
Picture of TD3550
posted Hide Post
Run a good synthetic fluid. Like Allison 295 fluid
 
Posts: 1409 | Location: Under a Truck | Registered: August 23, 2013Reply With QuoteReport This Post



DRR Top Comp
posted Hide Post
quote:
Originally posted by mavman:
Which brings in a question from me. When building up a powerglide, what do you guys do to reduce parasitic drag? I have Carl's book and have read it, but do you guys use the practices that he's written?


That's a helluva book. I talked to Carl (rip) about that book once, and he said he wished there were a little more profit in writing it, like maybe he regretted writing it possibly. Carl didn't say that and I may have read him wrong. But I told Carl one thing is for sure, no matter what,,,,, your name will live on.

And here we are keeping Carl alive, I think it's pretty cool.

He tells everything in there to do, it's up to you to read between the lines of what he's saying, in order to take it a step further.

My little 3200 lb sbc street car Nova can go double 0's on a .370 pro tree. That book of Carl's is responsible for a lot of the reason why.
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Pro
posted Hide Post
I do most of the "tricks" in his book and as stared above each mod may be hard to measure but I think the sum is worth doing. It is a good book.


Larry Woodfin



 
Posts: 1828 | Location: Kilgore TX | Registered: March 12, 2004Reply With QuoteReport This Post
  Powered by Social Strata  
 


© DragRaceResults.com 2024