My 198.4bhp vt'R' yo! *engine works (on predator)* - Page 30 - Saxperience

Sophia_Bush · 8th March 2011, 19:45

I shotgun passenger ride in this if I am ever at a track day same time as you

AndySAXO^p · 8th March 2011, 20:04

Yer werid them tranny losses, as NMS and TDF dyno both Cala the tranny loss on run downs, I seem to remember reading some sandy said about that dyno about the tranny low.

But I can't see my engine having the same wheel power as yours, would be nice though

Ryan^p · 8th March 2011, 20:19

James once stated a discussion that due to them being a 4wd dyno then halve the tranny loos then add it to the wheel figures.

Personally i dont see it myself.

The 183 figure would alone have more than the 143 ATW if you use the 15% loss calculation andy

I didnt think that NMS rollers were calculating on the run down and just used the mathmatical set up to add onto the recorded wheel figure.

Ryan^p · 8th March 2011, 20:22

This the comment from sandy you saw?

Quote:

Interesting though that the closest correlation to my engine dyno figures at another rolling road so far has been at Powerstation, one of the MAHA LPS3000s that give the seemingly crazy wheels/Tx loss figures and yet the closest flywheel figures I've seen so far. Some of the most bizarre figures I've seen have been on Dyno Dynamics, often touted as the most accurate, usually by their operators.

Dave_P · 8th March 2011, 20:32

I think everyone would agree 50-60bhp tranny losses are unrealistic on a MA box...?

Ryan^p · 8th March 2011, 20:37

Quote:

Originally Posted by Dave_P

I think everyone would agree 50-60bhp tranny losses are unrealistic on a MA box...?

Yet its made more than the 'up to 170 bhp in the real world' on other rollers.

Same as Roser/Nicks engine has.

Hence why its an interesting way to look at all of the results here.

AndySAXO^p · 8th March 2011, 21:10

Yer Ryan that be it, they do seem to give werid fly to wheel figures.

Well was told by NMS and TDF that they have one run down and cala the tranny loss then it saved as such, then after that it dosent need to do a run down after each run.

Might be wrong but it dose Cala the tranny loss I am sure.

And Dyno dynamics, I really dnt think them and spoken to a few mappers who dont like they, do to the way it calibrated or something.

Barry123 · 8th March 2011, 21:17

I don't think those sorts of losses are unreasonable. I mean you've got a load of cogs trying to spin at close to 100 times per second though the equivalent of treacle, heat build up and expansion of materials etc.

Still though, interesting to see that torque dip on both. Feature of the cams? Or lazy tuning low down on the mapping???

Ryan^p · 8th March 2011, 21:20

Quote:

Originally Posted by adsayer

I don't think those sorts of losses are unreasonable. I mean you've got a load of cogs trying to spin at close to 100 times per second though the equivalent of treacle, heat build up and expansion of materials etc.

Still though, interesting to see that torque dip on both. Feature of the cams? Or lazy tuning low down on the mapping???

Both engines are running 803s adam.

Mine has bigger TBs/valves/manifold and exhaust diamiter.

The thread I linked on the RR you should find interesting as it was when sandy first built his engine as theres a chat about the specs and the valve overlap.

I posted before elsewhere about the notable similarity in the dip although mine being slightly higher up the RPM range. Mine produces alot more torque earlier though, I expect the long inlet tract helping here.

KamRacing · 8th March 2011, 22:40

I think i've walked into a minefield.
Never trust a rolling road. Twin rollers are nothing like the real world..

Sandy309 · 11th March 2011, 06:55

I know this has been discussed elsewhere, but a little clarity is needed.

Rolling roads do not measure wheel horsepower, they calculate an estimate based on wheel torque (which is engine torque multiplied by the transmission bear in mind) and compare it to road wheel speed, sometimes correcting to allow for gearing, sometimes not. Then transmission losses are added based on further estimation from inertia response and/or run down torque.

The MaHa rollers mentioned take a different route to others to calculate estimated flywheel power, so you cannot try to relate wheels figures to other systems, the calcuations involved are different, the indicated losses are different; it's a different way to tray and establish a reasonable flywheel figure.

Look into it deeply, the software, the electronics, do you own testing and you'll find all that out. Although opinion varies regarding what transimission losses actually are, testing engine from dyno to hub dynos, we've found the actual gearbox loses around 8-10% of flywheel engine dyno power in almost every case. Tyres add to that, so around 30-35bhp loss real time, on a 200bhp FWD car is a realistic figure.

Secondly, the graph shown for Nick Charles' engine there is his 2008 spec, which made over 170bhp at the wheels on conventional Sun RAM XII rollers (spec calibrated) when I mapped it, about 10bhp or so more than when it was in James Rose's car with different manifolds/bodies.
Nick's 2010 spec engine that won us the CCRC Saloon championship is a further evolution of it, producing considerably more power than that shown.

Nick_C · 11th March 2011, 08:55

Quote:

Originally Posted by Sandy309

I know this has been discussed elsewhere, but a little clarity is needed.

Rolling roads do not measure wheel horsepower, they calculate an estimate based on wheel torque (which is engine torque multiplied by the transmission bear in mind) and compare it to road wheel speed, sometimes correcting to allow for gearing, sometimes not. Then transmission losses are added based on further estimation from inertia response and/or run down torque.

The MaHa rollers mentioned take a different route to others to calculate estimated flywheel power, so you cannot try to relate wheels figures to other systems, the calcuations involved are different, the indicated losses are different; it's a different way to tray and establish a reasonable flywheel figure.

Look into it deeply, the software, the electronics, do you own testing and you'll find all that out. Although opinion varies regarding what transimission losses actually are, testing engine from dyno to hub dynos, we've found the actual gearbox loses around 8-10% of flywheel engine dyno power in almost every case. Tyres add to that, so around 30-35bhp loss real time, on a 200bhp FWD car is a realistic figure.

Secondly, the graph shown for Nick Charles' engine there is his 2008 spec, which made over 170bhp at the wheels on conventional Sun RAM XII rollers (spec calibrated) when I mapped it, about 10bhp or so more than when it was in James Rose's car with different manifolds/bodies.
Nick's 2010 spec engine that won us the CCRC Saloon championship is a further evolution of it, producing considerably more power than that shown.

As Sandy said that spec engine discussed is about 2 evolutions ago. The spec i ran which won the Combe Saloons last year is quite a change!!
If your happy with the engine they thats the main thing.

Nick

jpsaxo · 11th March 2011, 16:58

I know about the engine you (Nick) and Sandy are talking about, some amazing power for a 1650cc!

Sandy309 · 12th March 2011, 06:55

1628cc! Less than most of the ones discussed.

jpsaxo · 12th March 2011, 09:56

Even better then. I'm assuming you won't state which cams you used on the engine... It's a crazy amount of power for NA, just shows your attention to detail I guess. The midrange is good as well!