Went to a dyno yesterday
Vehicle specs:
2010 XJ SuperSport, 130000km on a dash (70000 of these are in a modified form)
Upper pulley
Lower pulley
Bosch 010 pump
decat
both resonators removed, x-pipe installed
mufflers replaced
custom intake piping
regular paper air filters
On a road i've tested it with a Dragy and the 100kmh to 200kmh acceleration was 7.62sec, but i've had blinking DSC light all the way up to 140kmh. 1/4mile trap speed is 197.7kmh

First run was with a modified tune


Second run with a stock one (so that's a proof that pulleys are worthless without a software).



And, a few days ago, on a same dyno, the same SuperSport, but bone stock except for a sports cats and a tune measured...




As for me - im more than happy with a 850Nm

 

673 RWHP
Hello (or rather, GOODBYE) kitty!

 

Hey that's some great numbers and thanks for posting. We have only had about 3 or 4 guys dyno a SC 5.0L in an XJ too!

Did notice something that I have wondered about when I did my dyno run?
Why did you run it in 4th gear?
Is it because you have the 6 speed ZF and I have the 8 speed ZF?

Here are the ZF 8 speed ratios and 6th is 1:1 and I have always been told to dyno a car in the gear that is closest to 1:1?




In the 6 speed ZF 4th is the closest to 1:1 ratio.




Some say it makes no difference and others say it does?

I did mine in 6th and had trouble with the car holding the gear at full throttle. Operator said it kept kicking down a gear or two when he went all out.
He had to feather it up to a certain point and then lay into it.

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It's not rwhp, it's fwhp

 

Yep, mine's with 6hp, so the 4th is the closest to 1:1 ratio
I've disabled a kickdown in a tune for a dyno, so there were zero problems holding it in one gear.

 

clubairth, to answer your question as to why you always want to dyno a vehicle in a gear that is closest to 1:1 is simply to get an accurate reading of the torque. Torque is what causes a car to accelerate. Horsepower maintains a speed. The two are related by a mathematical equation. But, this assumes that you are in a 1:1 gear set up. Think about when you drive the car. How easy is it to break the rear wheels loose when in 4th, 5th, or 6th gear? Pretty hard. Now, how easy in 1st? Probably don't have to do much at all. This is because of 1st gear being at 4.7, the speed of the engine (aka, horsepower) is being converted to torque via the gearing. Because of the gearing, you are getting 4.7 times the torque than in 6th gear (where you are 1:1).

Can you dyno in different gears. Sure. But, it is going to skew your numbers a bit and not give you accurate numbers. If you have a dyno shop that is looking to run an experiment for you, do a pull in 4th and one in 6th and see how your numbers differ. I bet you will find a factor of 1.67 where your torque has gone up and your horsepower has gone down between the two runs. May not be exactly that, but it will be pretty close.

 

am I reading this correctly??

this car put down 669 at the wheels with just a tune and cats??

 

It's not wheels hp, its flywheel hp. But otherwise - yes, just a tune and cats.

 

ok! What company did you purchase the tune from?

 

Didn't purchase it, made it myself

 

So you took the engine out of the car to dyno it?
How did you measure flywheel HP?
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rwhp equals to fwhp minus transmission losses
most of the dynos are able to measure transmission losses and then shows the fwhp numbers (rwhp+losses).
as you can see - on a stock tune dyno measured 495hp (a bit lower than the original 510hp, but there's a lower exhaust backpressure in mine setup, which causes some power losses without reflecting these in a tune).
tbh 680 RWHP will be more than 800fwhp (and i haven't heard that anywone got close to this nubmers on aj133 w/o nitrous cheating)