Dnk Posted November 12, 2012 Share Posted November 12, 2012 (edited) I'm not looking for exact figures but whats the general consensus on how much the stock tt autobox loses from flywheel to wheels. I'm guessing its between 15-20 % so if you had a 400 fwhp figure at worst you would have 320 at the wheels 20% loss and at best 340 at the wheels 15% loss Any links to previous discussions please post them up Edited November 13, 2012 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
Slicknick Posted November 12, 2012 Share Posted November 12, 2012 SRR use 20% loss for the autobox. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted November 12, 2012 Share Posted November 12, 2012 SRR use 20% loss for the autobox. Really, that much? So a 1000fwhp will loose 200hp to the wheels? Thats a whole NA supe! Does torque converter make a difference as higher stalls are alot smaller carrying less fluid? Whats the average loss for a manual or isnt there one? Quote Link to comment Share on other sites More sharing options...
safcdixon Posted November 12, 2012 Share Posted November 12, 2012 im sure when we had the dyno day at evotune it was a 22% loss for an auto Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 Manual would be interesting to know too. Probably around 15% max? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted November 12, 2012 Share Posted November 12, 2012 Once you get well over makers design torque figures (from which BHP is of course computed) losses increase alarmingly as the transmission is flexing internally, as is the crown wheel and pinion in the rear axle. I did have a good link to sensible discussion of transmission and tyre losses, if I find it, I'll post it. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted November 12, 2012 Share Posted November 12, 2012 Here you are, Dave Baker was a real professional but lost heart with the job as companies with rolling roads were inflating power figures to create work and reputation. http://www.max-boost.co.uk/max-boost/internet_articles/Puma%20Race%20Engines%20Technical%20Guide%20-%20Measuring%20Engine%20power%20-%20engine%20dynos%20and%20rolling%20road%20dynos.htm and http://www.pugheaven.co.uk/Transmission%20Losses.htm Quote Link to comment Share on other sites More sharing options...
richarde7927 Posted November 12, 2012 Share Posted November 12, 2012 If you want dunk i will work out the trans losses from yesterday. Rich. Quote Link to comment Share on other sites More sharing options...
JamieP Posted November 12, 2012 Share Posted November 12, 2012 SRR use 20% loss for the autobox. You sure about that? I thought there dyno was set to 15% for rwd cars no matter what the gearbox was. Quote Link to comment Share on other sites More sharing options...
Chris Bailey Posted November 12, 2012 Share Posted November 12, 2012 If you want dunk i will work out the trans losses from yesterday. Rich. Yeah that would help Quote Link to comment Share on other sites More sharing options...
richarde7927 Posted November 12, 2012 Share Posted November 12, 2012 Yeah that would help Ok ill get on that tomorrow . Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 Here you are, Dave Baker was a real professional but lost heart with the job as companies with rolling roads were inflating power figures to create work and reputation. http://www.max-boost.co.uk/max-boost/internet_articles/Puma%20Race%20Engines%20Technical%20Guide%20-%20Measuring%20Engine%20power%20-%20engine%20dynos%20and%20rolling%20road%20dynos.htm and http://www.pugheaven.co.uk/Transmission%20Losses.htm That's a good article Chris. Seems reasonable albeit a guesstimate. So at 1 bar my car made 335rwhp which equates to 392fwhp, sounds fairly accurate. Max of say 12-14% transmission losses on a manual. Quote Link to comment Share on other sites More sharing options...
Chris Bailey Posted November 12, 2012 Share Posted November 12, 2012 That's a good article Chris. Seems reasonable albeit a guesstimate. So at 1 bar my car made 335rwhp which equates to 392fwhp, sounds fairly accurate. Max of say 12-14% transmission losses on a manual. So what would of my dads been, It made 443rwhp and its an auto? Any ideas after you read that whole post Lol. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted November 12, 2012 Share Posted November 12, 2012 So what would of my dads been, It made 443rwhp and its an auto? Any ideas after you read that whole post Lol. It should be 540.4 at the flywheel if the autobox loss is 22% Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 So what would of my dads been, It made 443rwhp and its an auto? Any ideas after you read that whole post Lol. About 540fwhp given the estimate transmission losses mate Quote Link to comment Share on other sites More sharing options...
Chris Bailey Posted November 12, 2012 Share Posted November 12, 2012 Cheers guys, Not to bad. I find it odd how every dyno reads different. A couple of weeks back it made 553.0fwhp at SRR Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 Cheers guys, Not to bad. I find it odd how every dyno reads different. A couple of weeks back it made 553.0fwhp at SRR Well just that article alone regarding tyre pressures is very interesting. Huge difference when psi is dropped as wheels sap the power if under inflated. So many variables. I'll be going by pure RWHP in future with the right setup. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted November 12, 2012 Share Posted November 12, 2012 Cheers guys, Not to bad. I find it odd how every dyno reads different. A couple of weeks back it made 553.0fwhp at SRR Maybe the autobox saps 25% of the flywheel power Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 Maybe the autobox saps 25% of the flywheel power As above and that article mate just too much guess work. Only true way to measure is to run RWHP and then engine dyno on exact same conditions and variables. At least then you could accurately measure the difference giving you your tranny losses. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted November 12, 2012 Share Posted November 12, 2012 As above and that article mate just too much guess work. Only true way to measure is to run RWHP and then engine dyno on exact same conditions and variables. At least then you could accurately measure the difference giving you your tranny losses. That sounds the best way mate. Will have to get my car on the dyno measuring fly and wheel power. Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 That sounds the best way mate. Will have to get my car on the dyno measuring fly and wheel power. I believe to do that at flywheel accurately is actually an engine out job mate! May be wrong. Chris W will know. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted November 12, 2012 Share Posted November 12, 2012 I believe to do that at flywheel accurately is actually an engine out job mate! May be wrong. Chris W will know. Oh I didnt know that. Chris how did SSR measure fwhp? Quote Link to comment Share on other sites More sharing options...
Sheefa Posted November 12, 2012 Share Posted November 12, 2012 They would of had to estimate it I would imagine. If they did the in neutral coasting tactic to find out potential losses as per the article it's not accurate as no power is running through the drivetrain. Have you got your dyno graphs available? Quote Link to comment Share on other sites More sharing options...
Kaan W Posted November 12, 2012 Share Posted November 12, 2012 They would of had to estimate it I would imagine. If they did the in neutral coasting tactic to find out potential losses as per the article it's not accurate as no power is running through the drivetrain. Have you got your dyno graphs available? Who me or Chris? Quote Link to comment Share on other sites More sharing options...
Dnk Posted November 12, 2012 Author Share Posted November 12, 2012 You need to run the engine on an engine dyno if you want exact flywheel figures. Quote Link to comment Share on other sites More sharing options...
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