I know this topic has been covered in a few threads but I thought I would combine everyone's wisdom and advice into its own seperate thread about maximizing anyone's dyno pull for their STR.

We all know the various purposes for a dyno, but some of us just like to use it as an automotive tape measure to measure our car's private parts lol. In other words, we wanna know the big numbers we are putting out. It seems like many people here have had failed dyno runs, including those with noteworthy modifications like smaller pulleys, etc., making numbers less than Jaguar's claims for a stock STR, even after factoring drivetrain loss. It seems these cars are not able be successfully dyno'd. Or perhaps they are?! Let's look at some to-dos as posted by various members until we crack the secret as to what it takes to make proper numbers.

Most of the info I am stating comes from various members on here, including (but not limited to) Avos who has had successful dyno runs in his XKR:

1) turn off the DSC via switch on dash

2) turn off anything that will tax your serpentine belt (i.e., your air conditioner)

3) try to have your car free of heat soak (I guess best way is to arrive to your dyno session very early if your are driving your STR for the pulls, park outside and open up hood and wait, wait, wait for things to cool off until your appointment)

4) for a dyno that has a single drum (recommended by Avos) then Put it into 4th gear via the j-gate, and DO NOT give it wide open throttle until you are over 4,200 RPMs (to avoid It from downshifting into third gear)

5) for a dyno that has dual drum, use 3rd gear on the j-gate

6) make sure techs open up your hood during the dyno run and have a powerful, industrial fan blowing on your engine to replicate real world air flow

Anything else you guys would suggest? Has anyone thought of disabling the DSC altogether by locating and pulling its fuse? Or would this cause check engine light issues? Please chime in with purposeful advice guys, I want to dyno my car for our members here so they can see what my mods make for their own purposes.

 

You basically covered all. I'd recommend a hard re-set of the ECU every few months to try to clear out most adaptaptive learning then drive her hard for a period prior to dyno.

 

I have a few questions before I start looking to see who will dyno my car.

First, which dyno makes should I avoid as being heartbreaker dynos? Which is best? Dynojet Research? Dyno Dynamics? Mustang Dynomemeter? Any others?

Also, it seems many shops now have AWD dynos due to the popularity of AWD vehicles today. Is there a drawback to running a RWD car on these? Will I lose power pushing both the front and rear rollers with my rear wheels only? Despite the manfacturer's claims that AWD dynos measure RWD/FWD just as accurately, does the STR's sensitive DSC kick in in any way if it senses the front rollers going in any rate that the rears? Should I use a RWD dyno only?

 

Never had any issues to dyno these cars myself, just take your time when you do a dyno.

1 Correct
2 Not needed, at WOT the ecu will turn these off
3 If you park your car, the engine heat (more than 90C) will then radiate into the intercoolers, making them also very hot. So place your car on the dyno as quick as possible, have the engine run, so the engine fan will cool down the intercooler radiator as well, I actually turn on the arico, so the engine fan will run faster. Feel the intercooler, it should not be hot to touch, so take your time and don’t rush.
4 Correct
5 Avoid these dynos if possible ;-), go for the single drum per wheel ones.
6 Correct, as most do not have any fan that mimics true airflow whilst driving, better to have the hood open.

Some more:
7 Make sure your tires are inflated correctly; I have them usually close to 2.5 bar
8 Make sure the dyno also measures your A/F ratio
9 Make sure you note the environmentals, so temp/baro.
10 Make sure you have the correction factor, and most important, get a slip the shows corrected hp based on either DIN or SAE (Not SAE STD).
11 Ideally make 2 or 3 runs, and again take your time in between again.
12 Don’t reset the ECU just before a dyno run, you want an honest run, so what you normally get on the street with the adaptations the ECU has set.

Most issues I read on this forum are on dynos that have small dual drums per wheel (Ie some mustang dynos, not all, Dyno Dynamics), not sure why, could be that these are harder to operate.

Best to go for larger single drum per wheel dynos (and also rwd, not awd), like Dynojets and some Mustang dynos as well which are meant for really high powered cars. On the next page you will see some musting dynos, and starting with the MD800 are the good ones.
2WD DYNAMOMETERS « Mustang Dynamometer Home: Chassis Dynamometer and Engine Dyno Experts; Dyno and Dynamometer Manufacturer

 

Avos, can your 631 chp 4.2 twin screw 2000 XKR dust a ZO6 Vette and/or similar metal?

 

Isn't the Z06 plastic?

 

LOL, U got me. Yes the ZO6's body is glass, but with either an aluminum and/or steel chassis. The 03 STR has one more year of payments, allowing me to put an 07 XKR on the wish list. Though the STR will stay, I've been imagining a twin screw equipped 07 XKR in the stable. Just wanted to pick your brains on how/if your XKR runs with other performance cars.

 

Assuming similar gearing, weight is the next important factor besides hp, so I don't think I will be faster with my 1920kg then the z06, but then again these are so different cars, it’s not really a comparison.

There isn't much racing around here, besides some subtle accelerations here and there, so have no real comparison data, but you can imagine mine isn’t slow ;-)

 

I shocked the owner of a Z006 on the highway about 6 months ago. I was able to stay on his bumper to about 130 mph at which point we ran into traffic. When he pulled over & I pulled alongside him he just shook his head.

 

Safe to say a T/S XKR is plenty fast. Thank you guys.

 

Was this in an STR? Mods?

I'm assuming it was a C5 Z06, as the C6Z's are plain nasty.

 

You guys also need to remember that the dyno is a tuning tool. Some places adjust the correction factor so that every car that gets on the dyno is a monster and other places might be low.

As long as its a good dyno that reads consistently from run to run, the numbers you start with are much less important than making sure each mod you do shows up in your runs ect. Unless you want to be like some of the supra guys and build a car that dynos 1000 rwhp but all you do is get on forums to brag about numbers and never take the car to the track, who cares if the numbers the dyno spits out are 5 hp low from what you think they should be.

 

Jgaxkr has an XKR with twin-screw and different gearing, and would be way faster than a C5 taking also the weight into consideration, so it must have been a C6 or faster.

I was actually thinking of the 638 bhp Z06 in my earlier post (that was the first one that that showed up in google for me). The standard C6 would have about the same power to weight ratio with mine, so that would be about the same.

 

Avos thank you for your knowledge. I found the perfect shop that has the right dyno based on all your wisdom, now I just have to find time in my hectic life to get it there! I will dyno my car as soon as I can so you guys can see what to expect with similar mods and what it all puts down on the street (i.e., 1.5 pulley, magnaflow cats, resonated x-pipe, and even larger, albeit equally weighted 19" wheels)

 

avos, the ZR1 developes 633 hp (6.2 L s/c), whilst the ZO6 is 505 hp. 7.4 L N/A. Your XKR would likely take out the ZO6 and trouble the ZR1.

 

I must be lucky, I have a dyno within 100 yards of me, and then another at 1.5 miles, and another at 3.5 miles. I will be dynoing mine after the 1.5 pulley in Dec (no point in installing it now when its 110*). Looking forward to Under Pressure's results.

Also would love to hear a sound clip Under Pressure

 

Just out of curiosity, anyone ever dyno a stock STR?

 

You may be right, I only looked at the power to weight ratio, and then my xkr would be at a loss against the ZR1, however I have just looked up the gear ratios, and then mine are much more favorable, bringing them at about par, not sure who would have the edge then.

Now lets see some good STR dynos.