R32 Gtr - Is My Mph Low?

[JH32]

I took my R32 GTR down to the drags tonight for the first time, and while I ran an 11.7 which I'm reasonably happy with I'm a bit concerned about the MPH. I have read quite a number of threads on here and given what others have run with similar setups I thought I would be quicker.

My previous R32 made 410rwhp (roller dyno) and this one made 470rwhp on a hub dyno. Now sure, dynos are dynos and the true measure is MPH at the strip. However, my last 32 did 11.8 @ 118mph on that horsepower, and my current 32 went almost dead on the same at 117.5mph. I had 4 runs all up, 11.7 then missed gears on the next 2 and then the fourth run I did a 12.0 @ 116mph.

I read through threads such as Marko's and with 325rwkw he was getting low 11s so I thought I would at least get 120-122mph. I have also studied the how to launch your GTR threads, the quarter mile in your 34 GTR thread etc etc. http://www.skylinesa...-gtr-the-creek/

Being that it was my first time at the drags with this car I didn't think I was going to get a great ET but should I have been expecting a higher mile per hour, or is it about on the money?

Here are the results from my first and last runs:

First

60' - 1.780

330' - 4.968

660' - 7.613 (speed was 151.73kph)

1000' - 9.863

ET - 11.776

MPH - 117.49 (189.08kph)

Fourth

60' - 1.757

330' - 5.052

660' - 7.771 (speed was 147.84kph)

1000' - 10.112

ET - 12.062

MPH - 116.73 (187.85kph)

The car's running a GT3582 @ c.19-20psi, has cams but not sure of specs, twin plate clutch. Tyres are Falken Ziex ZE912s (245s). Launch method was supposed to have been slip the clutch out at about 7000rpm but it turned into more of a sidestep at 7000rpm, and I tried to change gears as quickly as I could at about 7500rpm.

Any insight, particularly with reference to the above times at various points down the track, is muchly appreciated so I can practice a little more knowledgeably next time

[2rismo]

Cars, dynos, tracks... all have variables. I'd say your time/mph are about right.

[R31Nismoid]

In a heavier than stock R33 GTR (larger sump, radiator, brakes, coolers, 18" wheels etc) - I was running 11.4 @ 124mph with 335-340rwkw.

You are in a much lighter car with a tad less power (410rwhp = 305rwkw), so you should be pretty much the same to be honest. I'd say your setup has issues.

Your 60fts are good (so it's not a clutch problem) and your MPH isn't necessarily "too" low, but you would expect to be 120-122MPH at the least and that means you are probably not even making 305rwkw to be honest. A friend of mine years ago ran 117-118mph on stock turbos in a R32 GTR

Also the fact you have a GT35 @ 20psi and only 305rwkw, is also telling something. A GT35 on that much boost you'd be expecting closer to 350-370rwkw on a stock motor. So combined with the MPH, it's telling you there is something pretty wrong to be a good 8-10MPH down on what that turbo/setup is capable of.

[mattie4270]

Yes the power seems a bit low,ive got basically the same setup,350Kw on 98ron and 400 on E85

[mico]

im making around 330awkw with a gt35.82, 20psi bp98. standard cams rebuilt head my boost has jumped a bit so could be making mayb 340kw. have u changed your valve springs mate ?

[JH32]

Hi guys, many thanks for the responses. Mico, I'm not sure to be honest mate, the cams were installed by the previous owner. As R31Nismoid indicated the MPH seems reasonable for a low 300 kilowatts but given it last dyno'd at 470rwhp (hub) I agree, there must be something at fault with the setup.

Thanks guys, I will look into it As least there's potentially a few more MPH in it without changing too much!

[R31Nismoid]

Often you'll find hub results are not the same as a chassis dyno. They tend to read higher, so I'd still say you've got less than 300rwkw (which 117mph would suggest).

So easily down 50-70rwkw, which you'll notice once you get it - it'll be a different car and you will easily pick up 8MPH. Possibly a bit more.

To give you some perspective. A GT3076 (500-550hp turbo) will make around 300rwkw on 20-22psi. You have a 700hp turbo, that on 20psi has made 350/370rwkw on many many cars. A quick check of the dyno results thread would show you how easy and how many have done it :

[JH32]

Cheers mate, I keep a regular eye on that thread which is why I thought something was amiss given my 118ish mph. The ~330rwkw mark was always my 'target' I suppose so I'll get it back on the dyno in the new year and see if we can't figure out what's happening.

Cheers again for the feedback, appreciate it

[sultanaz]

i ran 11.8 on 234kw on 98 octane stock turbos just replaced with steel wheels
stock ecu , ku31s all round. ( excuse my screaming after the race... was tad excited )

time slip is in description.

got abit of a list of parts to buy.... keen to see my future result. Edited May 18, 2013 by sultanaz