average power

[rob77]

I remember SK talking about average power a while back. This is my latest dyno chart, 1.2bar wasnt tried as it seems the turbo is running out of puff and/or the stock exhaust manifold is restricting its flow. Can anyone tell me what the average power is?

[DoughBoy]

All the area under the curve

heheh or not!

[rev210]

Rob,

Thats a bloody good power band. At 4500rpm your making 223rwkw and it keeps nice and fat up top too.

I'd say with a set of cams in that power band will look even meaner. Give me a go at it next time at the drags mate and I'll get the bastard to do a mid 11 for ya

[Jay95R33]

I'm not sure what range SK usually uses to get the average power figure.

I suspect it would be somewhere around the ~3000 to ~7000 range.

One thing, if your going to start comparing average powers, make sure you use the same range and the same amount of points so the equation is the same.

Looks tough though, how do you go with traction as it goes from about 170rhp to ~280rhp in 500rpm.

J

[knore]

nice power

no point going over 6500rpm in gear changes tho as the power drops off

[rob77]

With 265 rubber on the back traction is still an issue, its only cheap rubber I want to put some decent rubber on when I put the other 2 18" rims I've got on. I've yet to give it full throttle in any gear yet, wheelspin in 2nd and 3rd as boost comes on quickly havent gone too hard in 4th. Really need to get down to the motorplex and give it a run down the 1/4.

[Roy]

I see you list of mods, but i dont see any susp work? Tyres do wonders for traction, but so does good suspension

[rbs13]

i dont think a tdo6 would would run out of puff at those revs with low boost.. correct me if im wrong.. but shouldnt you be able to run say.. 1.5bar for more power maybe then id expect it to run out of puff.. but not on 1.2 bar..

[Sydneykid]

Hi guys, the concept of average power is to calculate the power the engine generates as you change up through the gearbox. Since the first to second gear ratio change is the most wide spread in a Skyline box, I use the rpm drop on that gearchange. Usually around 3,000 rpm is the drop first to second, second the third is around 2,500 rpm, third to fourth around 2,000 rpm and fourth to fifth around 1,500 rpm. My next step is to choose the highest rpm I want to use and them subtract 3,000 rpm. I then take the power at 500 rpm increments and divide it by 7, the result is the average power from 4,000 rpm to 7,000 rpm.

So let's do rob77's car;

7000 337

6500 364

6000 357

5500 345

5000 330

4500 290

4000 161

Average 312

Knore said

no point going over 6500rpm in gear changes tho as the power drops off

But if I do the average power calcs using 6,500 rpm as the max;

6500 364

6000 357

5500 345

5000 330

4500 290

4000 161

3500 113

Average 280

So I would most certainly recommend using 7,000 rpm, at least in first gear as it results in a higher average.

Hope that helps

[Sydneykid]

I remember SK talking about average power a while back. This is my latest dyno chart, 1.2bar wasnt tried as it seems the turbo is running out of puff and/or the stock exhaust manifold is restricting its flow. Can anyone tell me what the average power is?

Hi rob, having explained average power, I will try and answer your questions;

Personally I don't think the turbo or the exhaust manifold is the problem at the moment. My experience has been that the standard camshafts are the most likely first limiter over 250 rwkw. They simply don't have enough lift or duration to let the air into the engine. Sure you can turn the boost up and try and squeeze some more air in, but you will get higher inlet air temps and lower efficiency.

Plus it will do nothing to smooth out that big jump in horsepower (113 at 3,500 rpm and 290 at 4,500 rpm) that I would find most difficult to drive through.

So I would recommend a pair of Tomei Poncams 256 degrees that are designed to work with the VVT. Obviously they will help the the engine breath better in that 6,000 rpm to 7,000 rpm range that you currently have a drop off in power. But my experience has been that they will also bring on the boost around 500 rpm earlier.

What I would expect is around a 50 bhp increase at 3,500 rpm and a 30 bhp increase at 7,000 rpm and about 20 bhp everywhere in between. Even off boost we see a power increase from fitting these camshafts. It is worth remembering that Tomei seem to get the timing pretty much spot on, so an adj exhaust camshaft pulley is not necessary.

All of the above is dependant on your tuner understanding the concept of increasing the average power, not simply aiming for more max power at one rpm point.

Hope that helps some more

[Cubes]

If the engine were the larger rb30 would you also recommend the 256 cams or maybe a mix with a 256 inlet and a 264 exhaust?

[xRHETTx]

Wouldn't torque be a better measure of the average output of your engine? As power is simply a product of torque and (sort of) rpm, isnt torque a better measure of the ability of your car to speed up, being rpm independant? Or is the average power just a figure for people who like to have a power figure to quote?

Im probably wrong though.

[nd4spd]

GTST Vspec has 330rwkw on standard cams and its only the fuel pump holding it back so dont blame cams.

[Cubes]

GTST Vspec has 330rwkw on standard cams and its only the fuel pump holding it back so dont blame cams.

:bs!:

Are they both using the same turbo's?

Obviously if a turbo is at the edge of its efficiency then a set of cams will do wonders, cams reduce the amount of boost required to flow x amount of air.

To make more power you can either use a larger laggier turbo or start looking in to improving air flow in to the pots.

[Cubes]

.

[RNS11Z]

Cams definately hold back. Yes you can make over 300rwkw but after 6500rpm you lose alot of power.

Here are 2 of my dyno graphs. One with a T88 (345rwhp) and gt30 (420rwhp).

(only using dyno graphs to show how power was made and were it was dropping in power. Disregard the figures).

[Col-GTSX]

Choice... very impressive... that power it nothing to laugh at... You have half of the right mods already. Forged pistons check, FMIC check, Exhaust Check & nice turbo. What i dont see as impressive is a wolf3d computer... Sorry but when i worked in auto electronics we used those on Gemini's and Escorts... Older Map sensor driven motors like the 2l twin cam ISUSSO (howeva u spell it) anyways... I believe out of personal experience, your greatest power gain is gonna come through 4 things... (not gonna say which one is best, as all four applied together is the way to go)

1. ECU (suggest Microtech)

2. Cams (suggest JUN or any of the good aftermarket ones, just select carefully on cams as some will provide great top end and some will provide great bottom end. Remember the standard ones are sort of all range. So get loads of advice before sinking into a certain set.)

3. AFM unit (Z32 or larger, standard afm's can only measure a certain amount of flow)

4. Fuel system (back to front, ie. Pump, surge tank, fatter lines, preasure reg, injectors)

Never the less these 4 bits (parts & labour) are gonna cost a pretty penny.....

[Col-GTSX]

Oh.... Almost forgot...

You were talking about tyres... Yep did these research a few months ago...

Meet a really smart bloke from CAT racing, works on the V8's anyways. Yes you do need a good suspension setup to obtain good use of tyres. There are a couple of ways to look at it.

1. I have the best suspension setup in the world and use $50 tyres...

2. I have a standard suspension setup and use $500 tyres....

3. I spent about $1200 on new springs and shocks (in a rep brand, ie I bought TEIN) and i buy good safe road tyres (ie. Bridgestone Donuts) $160 per tyre....

Now i have had all three of these setups over my last couple of skylines (all the same model) so i can tell you my last skyline which had option number 3 was the best handling of them all....

I will also go on to note that alot of people go on about $300 tyres and how good they are. Well i agree, $300 tyres are fantastic, but value for money over a Australian re-searched and made tyre (designed for our rough, course, dry, wet, bumpy roads) is not so great. So i took the advice on board and bought a set and they are now 2 years old and the fronts are now due for replacement. The $320 yoko's i used last time felt a bit better but only lasted 4 months...

Hope you under stand..

[N I B]

GTS tVspecs RB25 revs to 8000rpm and does not fall over there but we set the limiter there.

[BU5TER]

and its still using standard injectors and cams?