Scott Posted January 20, 2012 Share Posted January 20, 2012 I'm not convinced, I think tdis numbers for our cars was fairly spot on, reason being the 1/4 mile mph of my car for the weight, now I know its not accurate but most of the calculating sites say that with my power and weight I should be doing 97-99 mph, which suggests I have a true 230 fwhp NA. Yours obviously has the stronger engine or I wouldn't be going to the hassle of buying it off you. Scott I know you disagree with the above as it has been talked about before, but for arguments sake until it goes to the hub dyno and weigh bridge let's assume its right. Those things that calculate your terminals are based on American RWHP. Take from that what you will as I don't want to get into that argument all over again. If you took your car over to the US as it currently stands, IMO, it would make over 200RWHP thus making those calculations spot on. As it stands your car is approx 180RWHP in the UK. If you take the US terminal figures based on FWHP rather than RWHP you will get a good idea of what you can potentially hit. There are obviously a lot of other variables that come into it but at the lower power levels I'm guessing the figures will be easier to atain. TDI's hub figures vs FWHP figures are still to be figured out. JP has his suspicions that the RHHP figure from TDI is actually closer to FWHP rather than RWHP so he now just quotes it as RHHP to save any confusion. The guy from Ireland ran his UK spec on the TDI dyno and came out with over 480hp for example, because he made something like 390rhhp and divided it by 0.8. If you take your car to SRR and put it on the rolling road you will be able to see what power it makes on the Supra yardstick. That's not to say SRR is correct, it's just seen as the yardstick for our cars. It would give you a true representation of where your car is sitting vs all the N/As, TTs and Singles that have been there over the years. Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted January 20, 2012 Author Share Posted January 20, 2012 232.6fwhp = 186rwhp. I have no issue with believing around the 180rwhp mark from an N/A. The readings do sound a little bit high but +/-10hp isn't a lot to argue over. 1 dyno will see you over 200rwhp, another will see you with 180rwhp. Anywhere inside those figures is fantastic IMO, already spoke to Martin about this, both were very healthy How is the fwhp to whp coversion worked out? my math is not my strong point (along with many other things) i have always just gone of the dyno plot that TDi gave me which was just over 200whp corrected to 232.6fwhp i am guessing using a 15% loss correction. I however know dynos are nothing to go by and are just a tuning or reference point tool *edit* You pretty much just answerd it lol. Quote Link to comment Share on other sites More sharing options...
Scott Posted January 20, 2012 Share Posted January 20, 2012 How is the fwhp to whp coversion worked out? my math is not my strong point (along with many other things) i have always just gone of the dyno plot that TDi gave me which was just over 200whp corrected to 232.6fwhp i am guessing using a 15% loss correction. I however know dynos are nothing to go by and are just a tuning or reference point tool *edit* You pretty much just answerd it lol. Yeah TDI has given you 200RHHP, not RWHP. Not really sure what to use as the loss as if we take the usual 20% for auto and 15% for manual then you would have 250fwhp and 235fwhp respectively. I would say this is widely accepted as not possible on an N/A, going by the SRR yardstick in the UK at least. That's only taking the usual suspect mods into account though as higher figures will be possible with a lot of work. I believe around 300hp is the record? If you took it to another dyno you would get another figure, it might be higher... it might be lower, it can't be said that 1 is right and 1 is wrong because without actually sticking the car on a chassis dyno you're never really going to know. If you did a tour of the UK dynos and then quoted the lowest figure you achieved then you could be confident that the power you are quoting is the very least that you have. For the pub it's generally the highest figure atained that is quoted though. Theoreticaly, if you took your car to SRR and hit 180rwhp.... would you still quote 200rwhp as your figure because you achieved it on another dyno? Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted January 20, 2012 Author Share Posted January 20, 2012 Yeah TDI has given you 200RHHP, not RWHP. Not really sure what to use as the loss as if we take the usual 20% for auto and 15% for manual then you would have 250fwhp and 235fwhp respectively. I would say this is widely accepted as not possible on an N/A, going by the SRR yardstick in the UK at least. That's only taking the usual suspect mods into account though as higher figures will be possible with a lot of work. I believe around 300hp is the record? If you took it to another dyno you would get another figure, it might be higher... it might be lower, it can't be said that 1 is right and 1 is wrong because without actually sticking the car on a chassis dyno you're never really going to know. If you did a tour of the UK dynos and then quoted the lowest figure you achieved then you could be confident that the power you are quoting is the very least that you have. For the pub it's generally the highest figure atained that is quoted though. Theoreticaly, if you took your car to SRR and hit 180rwhp.... would you still quote 200rwhp as your figure because you achieved it on another dyno? If i just wanted to quote numbers i would head over to motorscope to get a 350bhp plot printed off I would like to go to SRR but it means a long drive down, i am hopefully going on a hub dyno soon though, should be interesting and depressing all in one go. Quote Link to comment Share on other sites More sharing options...
Scott Posted January 20, 2012 Share Posted January 20, 2012 If i just wanted to quote numbers i would head over to motorscope to get a 350bhp plot printed off I would like to go to SRR but it means a long drive down, i am hopefully going on a hub dyno soon though, should be interesting and depressing all in one go. Was TDI not a hub dyno? It's the hub dynos that are in question AFAIK. At the end of the day you can only quote the figure that you have been given, I wouldn't read into it though. Your car is making good power regardless so I would just take it as that. For example according to your current figure you have the most powerful N/A in the club by quite some way with Martin's old car at no.2 spot. Strange that eh Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted January 20, 2012 Author Share Posted January 20, 2012 No just a chassis dyno. Quote Link to comment Share on other sites More sharing options...
Scott Posted January 20, 2012 Share Posted January 20, 2012 No just a chassis dyno. Ahh, will be good to compare it with then. Would be good to see a car go on all 3 types to see what power it made on each Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted January 20, 2012 Author Share Posted January 20, 2012 How do you calculate rwhp to fwhp, i thought you x it by 1.15 for a 15% loss. Quote Link to comment Share on other sites More sharing options...
Scott Posted January 20, 2012 Share Posted January 20, 2012 How do you calculate rwhp to fwhp, i thought you x it by 1.15 for a 15% loss. No, you divide it by 0.85. FWHP is the full HP of the engine, RWHP is the power at the wheels after the transmission losses. RWHP = 85% of the FWHP. If you have the RWHP you divide it by 0.85 (for a manual) to get the FWHP. If you have the FWHP you multiply it by 0.85 (for a manual) to get the RHWP. Auto is the same as above only using 0.8 rather than 0.85. Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted January 20, 2012 Author Share Posted January 20, 2012 No, you divide it by 0.85. FWHP is the full HP of the engine, RWHP is the power at the wheels after the transmission losses. RWHP = 85% of the FWHP. If you have the RWHP you divide it by 0.85 (for a manual) to get the FWHP. If you have the FWHP you multiply it by 0.85 (for a manual) to get the RHWP. Auto is the same as above only using 0.8 rather than 0.85. I am getting confused now, going off that my car makes 197.71 RWHP, i cant be this thick can i Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted January 20, 2012 Author Share Posted January 20, 2012 Infact ignore me, i am boring myself now lol. Quote Link to comment Share on other sites More sharing options...
Scott Posted January 20, 2012 Share Posted January 20, 2012 I am getting confused now, going off that my car makes 197.71 RWHP, i cant be this thick can i It's best to take the RWHP and go the opposite way, rather than taking the FWHP and going to RWHP. RWHP is a measured value on a chassis dyno, FWHP is a calculation based on whatever the operator puts in. If you saw over 200RWHP from the dyno you were on then divide the figure by 0.85 to get the calculated FWHP. Whether that figure is accurate or not is neither here nor there as that's all you have to quote. However, if they calculated the FWHP to be 232.6 then 197.71 is the RWHP if they used 15% as the transmission loss. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.