Dyno Slip Discussion Thread

[bartc_j]

as it states..

[Joel07]

Man, are those cars from Finland still with the CA18ET?  That\'s some pretty awesome numbers...

[Arro]

Man, Dave in the UK has some big testicles between the front wheels of his S12.... nice :mrgreen:

[s13eater]

thought you might want to see these

[s13eater]

[vg30e_x2_200sx]

Is it a manual trans? If so I thought pulls were suppoised to be done in 4th (1:1) not 3rd.

[s13eater]

manual,i know a lot do it in 4th but an australian guy who runs another dyno dynamics RR at silverstone race track advised to use 3rd on dyno dynamics set up.what difference does it make running in 4th insted of 3rd ?

[wacomuk]

its to do with the gear ratio. 4th is normaly 1:1

[vg30e_x2_200sx]

what difference does it make running in 4th insted of 3rd ?

If you use 3rd instead of 4th you will show more power than the engine is making because of the mechanical advantage that is created by the underdriven output.
 
Basically the reason you have more than one gear is to achieve a mechanical advantage to get the car moving easier.
 
Therefore using anything but 4th (1:1) is not an accurate representation of the power output of the engine at the rear wheels.

[s13eater]

erm so why do the people who sell the dyno dynamics recomend 3rd gear, a supra 3ltr tt was on the rr at the same time, he was spinnig in 3rd so did a 4th run but there was not much difference in power on either run. i do believe that the boost i was running should of run a lot more bhp than i made, i have a few things restricting me,330bhp will be next, thing is i know the car inside out and what its made before, its done about 18 RR runs and still in one piece, some people do 3rd gear some do 4th, if the RR is set up right it don\'t matter, what power is your vg running, i had a z31 turbo, i wished that had the power that my tiny ca18et engine had, shall i get my next dyno run written in blood, will that be authentic enough, or will it have to be done o type negative to be true.where ever there a positive on tuning there will always be a jelous downer.

[vg30e_x2_200sx]

No jealousy at all. I\'m not claiming any misclaims by you at all. As a matter of fact I\'m impressed by what is seen, it\'s just a fact that with any mechanical advantage that the numbers will be silghtly scewed.

 
I\'m not one to have modified my car because it has been my daily driver since I purchased it and it has been extreemly reliable for that.
 
More power to ya and good luck with the hunt for more power.

[Jonny Cash]

No jealousy at all. I\'m not claiming any misclaims by you at all. As a matter of fact I\'m impressed by what is seen, it\'s just a fact that with any mechanical advantage that the numbers will be silghtly scewed.

  
I\'m not one to have modified my car because it has been my daily driver since I purchased it and it has been extreemly reliable for that.
  
More power to ya and good luck with the hunt for more power.

I myself have done 3rd gear pulls, and 4th gear pulls. The difference was about 3-4 hp in 3rd gears favor.

When you say RWD.. Does that mean this does not apply to FWD??

[s13eater]

cheers, i think the RR has to be altered for fwd,it has to be turned around on castors as it has one of the rollers with a knurled face :smile: .

[wimdepim]

you all run in 4th gear
my car they runned it in 5th and produce 185bhp

[nissanman]

I ot like 480NM of torque in 4th gear, but thats not acurate,
as in 1st or 2nd i was told you would have probably over 1000NM at the wheels.
It depends wat gear your in.

Weird cas i got 150hp in 4th gear and 475NM.
365 foot pound is nly 490NM....... but u got 305HP.....??????

[s13eater]

something wrong with those numbers mate, there\'s not usually that much difference between bhp and torque, 325 ft/lbs of torque is very healthy, i\'ve done some more tuning and i\'am hoping for some more power :wink:

[30PSI]

Nissanman - You need to understand the relationship between bhp, torque and rpm.

BHP= Torque (ft/lb) x rpm / 5,252

Now say S13eater has max torque at 5,000rpm 325 ft/lb\'s

BHP at 5,000rpm is 325x5000/5252 = 309 bhp at 5000rpm.

This doesn\'t mean his maximum bhp is 309bhp. Its only the bhp at 5,000rpm.

Now lets say his engine is a nice higher revver...

It makes 250ft/lb\'s at 8000rpm

BHP at 8,000rpm is 250x8000/5252 = 380 bhp at 8000rpm.

This could well be his max power but the power would have to be calculated from the rpm and torque info.

OK..

Now lets look at wheels, torque and BHP.

Say he\'s gear ratios result in the dyno roller turning 4 times slower than the engine. The roller would show 4 times the amount of torque. But at 1/4 of the rpm.

So working back to the 1st example of 325lb/ft\'s:

Roller speeds is 5000/4=1250 but torque is 325x4=1300lb/ft\'s

BHP at 1,250rpm is 1300x1250/5252 = 309 bhp at 1250rpm.

So to summarise torque, rpm and BHP are related directly. Change the rpm via gearing etc and this alters the torque. But the work done (power) remains the same therefore the BHP is constant.

[Candellan]

Hi guys. It's been a while.

I thought I'd update a few details here & put up a dyno sheet. It's slightly out of date now, but I haven't scanned the latest one. Latest power is 254hp (189.4kw) @ 6003rpm & torque is 329.5nm (33.6kg/m) @ 4386rpm. The power has also been smoothed out to help on track transitioning long/slow corners.

The engine is a CA20DET with standard CA20 (shot peened) rods & pistons (no forged internals), running a IHI TD05H-16G from an EVO III at 1.034bar (15psi) & rev limited to 7000rpm. ECU is a Power FC.

More details, videos & pics here - Gazelle MotorSport

[sideways_s12]

nice numbers I was wondering what the ca20det did on numbers good show...