Can You Calculate Aproximate Rwkw From Mph?

[Brokenz]

Anyone know the maths to calculate?

I took my 4dr r33 to the drags for the 1st time and these where the results. I am interested what they equate to in rwkws as I have not had the car dynoed recently

13.331 @ 114.74

13.073 @ 114.13

13.065 @ 107.32

Any help appreciated

[Sklyn]

Can I have a guess and say around 200 rwkw..

just guessing from my times..

[Kaido_RR]

i ran 13.0 @ 113mph and at the time my car had 251.7rwkw

Edited August 26, 2008 by [Michael]

[2rismo]

114mph for a car weighing about 3350lbs is 370-ish-hp (engine) or 275kW (engine).

I reckon your car is making about 220-230kW at the rears.

[BezerkR32]

ive had cars run 11.70 with 285rwk. i doubt 30kw=1.3sec. the mph shows about 220kw at the wheels. your mph is showing about 220ish also

  [Michael] said:

i ran 13.0 @ 113mph and at the time my car had 251.7rwkw

[Brokenz]

Thanks guys. So I can safety estimate it has at least 220kw which is what I was thinking.

[JAS-25T]

14.0 @98MPH............

oh.

no one showed me how to convert the other way around

[Duncan]

lol good work jase

[BezerkR32]

14.0 @ 98 came from my apprentices stock r32 4 door running 13psi on MTs.

not bad hey.

  JAS-25T said:

14.0 @98MPH............

oh.

no one showed me how to convert the other way around

[Lithium]

  Brokenz said:

13.331 @ 114.74

13.073 @ 114.13

13.065 @ 107.32

The power estimates mate on here have me confounded - ~220rwkw seems to be the accepted approximate power for an R33 running 114-115mph?

What is done to your car? On our dynos (well most dynos around the world) 220rwkw is achieveable at a stretch on a stock turbo but trap speeds >114mph are very much not achieveable with the stock turbo on an R33. To be running those kinds of times/speeds I'd be hoping to see you are running around 1bar of boost, maybe a fraction more otherwise I am about to get very depressed.

[2rismo]

I ran 111mph with no more than 200kW.

[JAS-25T]

  BezerkR32 said:

14.0 @ 98 came from my apprentices stock r32 4 door running 13psi on MTs.

not bad hey.

noofa! how's that guy doing I haven't seen him for a while.

[Lithium]

  2rismo said:

I ran 111mph with no more than 200kW.

I wasn't talking about the dyno power, I am thinking of almost completely disregarding Oz dyno results - they mess with my head. Now I am just talking about outright modifications, trap speed sounds like it'd be a better measure of what the engine and car is doing that trying to work out what on earth the different between your dynos and everyone elses is, I just want to know if his car is doing substantially more than what 220rwkw means to me if that makes sense?

My car has run in the same kind of territory trap speed wise, running ~14psi through a GT30R on a completely stock RB25DET on a fairly slippery strip (actually an airfield...) but makes much more than 220rwkw on the dyno I run my car on, well actually ALL of the ones I have run it on which includes a rolling road dyno it made 260rwkw on. What I am hoping to hear is that my car for the mods it has that the times/trap speeds in the conditions aren't TOO bad.

[2rismo]

Forget dynos then. The calculations I have used above take trap speed and weight and convert it to engine horsepower. I then converted that to rwkw. It could well be the case that this car makes 240-250kW at the back wheels but for this to be the case, it would relate to one or more of the following:

a/ weigh more than the 3350lbs I've allowed for

b/ have had a non representative run on the track

c/ been racing on a ridiculously bad track

d/ have had a schmuck behind the wheel

Don't get your knickers in a knot over chassis dyno figures. The big, black dyno never lies.

[Brokenz]

One of the reason I asked in my mate just got his GTR dynoed and was 490hp at one workshop and 404hp at a different workshop which makes me wonder how accurate these figures are.

I only had my car dynoed once at the last Nissan track day at QR Raceway and it was 192kw at the rear wheels but that was with stuffed coils breaking down at higher revs, and running .09 bar. Now has Splitfires and running 1.1 bar otherwise same spec. Car is in full street trim but has some mods HKS2535, Power Fc, 550cc Inj, Z32 AFM etc.

I will put it on the dyno next week and see what the result is, but I thought trap time might give a more accurate figure

[Lithium]

  Brokenz said:

I only had my car dynoed once at the last Nissan track day at QR Raceway and it was 192kw at the rear wheels but that was with stuffed coils breaking down at higher revs, and running .09 bar. Now has Splitfires and running 1.1 bar otherwise same spec. Car is in full street trim but has some mods HKS2535, Power Fc, 550cc Inj, Z32 AFM etc.

I will put it on the dyno next week and see what the result is, but I thought trap time might give a more accurate figure

Yeah this is the short of it, dynos are all over the place in readings - in Australia they seem to be all up the crapper as once I think I am starting to work it out a new strange result comes up. Dynapack, Dynojet etc used around the rest of the world have a bit of variance but they are all close enough to each other to get a rough idea.

I am glad to hear you are running ~1.1bar, its about what I expected for the trap speeds you were running (as said in an earlier post) - so long as its on a turbo which can more or less support it thats what it should trap. On the dynos I run on for what its worth, I'd expect it to be making in the territory of 250rwkw with a crap load of torque.

[2rismo]

  Lithium said:

Yeah this is the short of it, dynos are all over the place in readings - in Australia they seem to be all up the crapper as once I think I am starting to work it out a new strange result comes up. Dynapack, Dynojet etc used around the rest of the world have a bit of variance but they are all close enough to each other to get a rough idea.

I am glad to hear you are running ~1.1bar, its about what I expected for the trap speeds you were running (as said in an earlier post) - so long as its on a turbo which can more or less support it thats what it should trap. On the dynos I run on for what its worth, I'd expect it to be making in the territory of 250rwkw with a crap load of torque.

A correctly operated Dyno Dynamics chassis dyno in the appropriate shootout mode will register pretty well spot on regardless of weather conditions etc. Making sure it's operated correctly is another thing all together.

[Lithium]

  2rismo said:

A correctly operated Dyno Dynamics chassis dyno in the appropriate shootout mode will register pretty well spot on regardless of weather conditions etc. Making sure it's operated correctly is another thing all together.

By spot on do you mean more or less consistant with the other dyno types, or just consistant with other Dyno Dynamics set up for shootout mode? I have noticed that there seem to be occasional readings from DD dynos which seem similar to what I'd expect from a Dynapack.

[2rismo]

  Lithium said:

By spot on do you mean more or less consistant with the other dyno types, or just consistant with other Dyno Dynamics set up for shootout mode? I have noticed that there seem to be occasional readings from DD dynos which seem similar to what I'd expect from a Dynapack.

Spot on with other Dyno Dynamics chassis dynos run in the same fashion.

[R.I.P.S NZ]

MPH verses weight is the easiest and best way to get a pretty acurate guage the vehicles WHP.

If you can run X amount of MPH and your car weighs X amount, you must have at least a certain amount of whp to do it.

When we ran 162mph on street tyres in street trim, the power required to do so matched our dyno numbers within a few whp but in general I don't take much notice of dyno numbers as MPH doesn't lie.

Rob