Dyno Tested Auto Vs Manual Driveline Loss

[STATUS]

R33 series 1 FMIC, full exhuast, GCG GT3082R bolt on kit runs done at 18psi.

Auto 241.7rwkw (381.7nm) (thin blue line)

Manual 277.6rwkw (429.9nm) (thick blue line)

Auto 200rpm better response (normal of course)

Vct was set @ 7000 to produce best power and curve, red dyno line is vct set at factory point..... massive loss of mid range.

This VCT drop is very common on just about any turbo making over 250rwkw it just isnt as easy to pick up on with a inertia dyno, i see it alot in cars that come in for dyno runs.... moving the VCT point up towards redline until it smotths out is the bst way to fix it generally between 6200 and 7000 yields the best results.

Edited January 7, 2009 by URAS

[2rismo]

So it lost ~36kW over the manual. What's that, nearly 50hp? That sounds about right to me but what auto/converter is in it?

[FATAZZ]

Is it true the higher the convertor the more you loose through the dyno?

[Guilt-Toy]

Trent

Are you talking about the VCT rpm value you set in the power FC ? you have that set to 7000rpm?

[PM-R33]

So with regards to the VCT, what you'r saying is to keep the VCT kept on all the way to 6200-7000rpm? Or do you mean to have it activate at 6200-7000rpm?

[Guilt-Toy]

yup pfc set value. (switch point)

that value is where the VCT is switched off. The way i thought the vct works is that it switches on at about 1500rpm (cannot change this on pfc) then switch's off at 4000rpm (or whatever you have set in the pfc software)

So this means that you have a massive inlet cam advance all the way to red line... I was told the engine would start to ping if you did this, did you run the K-MON on this engine when tuning it ?

[STATUS]

Trent

Are you talking about the VCT rpm value you set in the power FC ? you have that set to 7000rpm?

yup pfc set value. (switch point)

[666DAN]

Would be interesting to see this with the R34 and their apparently "improved" electronic lock-up torque converter (Nissans "E-flow") either way I've always factored 33% loss in the autos, some people have been way to conservative on the actual loss.

[PM-R33]

Hmm interesting, might have to play around with this on the next tune. Have you found this only works with stock cams, or will something like Poncams still have the same benefit moving the VCT switch point that high?

[STATUS]

that value is where the VCT is switched off. The way i thought the vct works is that it switches on at about 1500rpm (cannot change this on pfc) then switch's off at 4000rpm (or whatever you have set in the pfc software)

So this means that you have a massive inlet cam advance all the way to red line... I was told the engine would start to ping if you did this, did you run the K-MON on this engine when tuning it ?

correct, i set the PFC switch point to 7000 (on this particular car)

K-mon is always connected timing curve is nice and strong.... no sign of det, even on the most aggressive ramp (1sec for every 370rpm or 15 sec in total)

[STATUS]

Hmm interesting, might have to play around with this on the next tune. Have you found this only works with stock cams, or will something like Poncams still have the same benefit moving the VCT switch point that high?

well on SR's (S15 etc) which run the same setup the results are similar with poncams, i think i have athids graphs (peak of 300rwkw but with varying midrange with each differrent switch point) somewhere where i incresed the switching point in 1000rpm increments on each run until it was smooth. i will see if i saved it.

[r33123]

thanks trent, i know u can figured a way to tune my r33 with aka gt3040 good results and smart thinking , iam very happy +100 for aka trent for tune this r33. intersting result with changiing of vct. cheers.

[dangerman4]

with the new wastegate actuator im at 330 rwkws

with a 2800 high stall and standard trans but fully built by MV Auto.

i should come for a drive to see you trent and then run the car at the street drags in melb.

i will be selling the car soon so it would be nice to see its potential before she goes.

[rob82]

Are you sure the VCT is working at all - I havn't seen that work before. I would have though that you would kill you top end - the engine has oil pressure right???

[Haines]

sooo the auto will be slower ?????

[Guilt-Toy]

Are you sure the VCT is working at all - I havn't seen that work before. I would have though that you would kill you top end - the engine has oil pressure right???

I would have asked this question, but i think trent knows what he is doing. it does sound far fetched but it takes a game tuner to try new things like this and put them to test.

So - i might do some testing next time i have my car on the dyno

[STATUS]

Are you sure the VCT is working at all - I havn't seen that work before. I would have though that you would kill you top end - the engine has oil pressure right???

yeah, i start from 4000rpm and move the point upwards until the area under the curve is largest/ smoothest. I only included one run (red one) on the print out as it gets pretty busy with 6 runs overlayed.

[joeyjoejoejuniorshabadoo]

pretty sure that racepace do this aswell

benno was saying something to me about playing with the vct a little while back but i forget now

[STATUS]

sooo the auto will be slower ?????

Hard to say without running it down the strip, i reckon from seat of the pants the auto with its shift kit was quicker especially outta the hole but no doubt the manual would run a better MPH.

[joeyjoejoejuniorshabadoo]

the auto's gonna take out a LOT of driver error on a 1/4...