Evening all just thought I would post my results from a rolling road session that I had yesterday at motorsport developments in Blackpool.

As in my sig the mods on my car are a K+N panel filter, my 80mm intake tube, 200 cell sport cats and a 2.5 inch cat back custom exhaust with X pipe to my own design, Royal purple XPR oil.

And the results, well surprised me at 462.4 hp at the fly ( 376.1 atw) and 650 Nm torque at the fly (540 Nm atw)! Using a dynodynamics dynotech 2400 hp capable rolling road.

Happy with that.

 

Surely that sounds to good to be true from basically a panel filter and exhaust system?

 

I noticed there is no numerical correction factor listed on the ticket. I would get that from the dyno guys, Problem being that many dyno operators plug in a 25% correction factor on a boosted motor at sea level, which of course means you need to cut your numbers by 25% (or whatever the CF is)

With your mods and being at sea level, using a perfectly healthy motor as an analog, I would bet you're making approx. 300-315 whp and torque being that the stock motors are faily "square". If you've added a pulley or software mods, then I suspect you could break 400+ on both at the wheels.

Just my two sense with messing with dyno's and such for a long time..

Regardless, your call seems very healthy and congrats. And you'll always have a guy a like me punching holes in said numbers.. ;-)

Cheers,

Jeff

 

Jeff,

I'm hoping to have my XJR dyno'd before I install a small pulley, then again afterward. Please help me understand how the correction factor is taken into account. If you increase a number by 25%, then reduce the resulting number by 25%, the result is lower than the original number. For example, 100*1.25=125, but 125*0.75=93.75. Wouldn't the reducing correction factor have to be smaller to correct for the original correction factor? In the case of my example, 125 is 25% greater than 100, but 100 is only 20% less than 125.

Thanks in advance for helping me understand.

Cheers,

Don

 

Hi Jeff,

Why does it not seem right if the standard bhp of an xjr was 400 bhp then 462.4 only represents a 15.5% increase bearing in mind the restrictions in exhaust and intake have been removed seems plausible to me.

I am quite confident the figures are correct, I did quite a bit of research before selecting the rolling road that I used, I have attached a link to the web site which explains the correction factors what they are and how they are calculated (good reading Don) on the bottom of the page is the link to all the technical articles that the operator ( and owner of the business Stu Sanderson) has written including one on dynos.

Motorsport Developments - All About Dyno Correction Factors

Also here is a YouTube video made by motor sport developments showing how it is possible to inflate the dyno numbers by changing air temp probe location.


When you read the articles and watch the videos you get the idea that these guys know what they are doing and are all about accuracy.

 

First part is my fault as I read foot pounds of torque as we record State side, so with the conversion, that puts you just under 400 ft lb's, which makes more sense..

Second is the correction factor AND the driveline loss they use, as those are important figures. Effectively, you have should have zero correction on a boosted motor unless it was terribly hot that day (looks like it was 66 degrees F that day or was that just the post dyno fan temp read?), or were above sea level a decent amount. I'm going to guess not, so the cats / exhaust and intake giving you 15% increase (and huge torque) is a bit suspect IMHO.

I would say your numbers with a pulley and software = no question and more.

At any rate, I'm not putting down your car, I've just witnessed so many dyno issues, while putting down some fairly large numbers in five cylinder turbo Audi's, it's almost laughable.

If you are comfortable with it, post the correction factors and drive-line loss calcs they use. The only interesting correction that might be arguable is the parasitic drain on the motor having to spin the supercharger, but that would fairly small I'd imagine (vs. non on a turbo motor of course).

Cheers,

Jeff

 

I will get the correction factor although as it was on the coast etc this may well be zero as you intimated. The driveline loss is easy to work out, we have the chp and the wheel hp one divided by the other gives approx 20% which it looks like most use on other posts and from your estimations it's what you have used to estimate the power of my car (400 chp less 20% being around the 320 whp you have posted) obviously that may be true of a standard car but what do you base the fact that I have apparently gained no hp whatsoever from exhaust, sport cats and intake mods plus running on 97 Ron fuel? That is the bit I don't understand and if you could explain your grounds to make that assumption it would be great. My experience if you make the intake and exhaust flow more efficient then power must be created.

We also know that the ecu s adapt ( look at avos' car over 600 hp on standard ecu so tuning is not necessarily required although obviously a further gain may be possible) the pulley is another mod that really doesn't affect peak power that much mid range absolutely but the combination of tune and pulley would not give 85- 100 bhp at the wheels as you suggest. Remember this is a supercharged motor not a turbod unit where the boost can be upped with far less penalty ( it's not called a Heaton for nothing!)

Like I said the figs seem plausible at only 15% gain in power over standard, I will confirm the correction factor just to be sure though.

Thanks.

 

Interesting thread. Subscribed!


Caldoofy, can you elaborate on the Stage 1 and 2, intake tubes? Thanks.

 

Don't want to be negative but the numbers do seem very optimistic.

Caldoofy, have you been for a run at Santa Pod? What was your trap speed in mph?

Trap speed in mph is much more comparable, and we have a few X350 XJR's that have run the 1/4 to compare with.

 

My car stock did something like 312 at the rear wheels on that same dyno. Currently I have your intake with the mina cold air kit and an Arden back half exhaust. Feels substantially better now than stock. Was going to put on my rebuilt later model blower with pulley and ECU tune however I bought one of AVOS's twin screw kits...Kind of put my dyno aspirations at a halt now. Did you have an exhaust shop do your cats or are they the nameless ones?