Hi Guys,

I hope someone can help me out here.

This morning I took my N/A for a dyno remap. One the first run it was showing only 192bhp at the flywheel so a loss of 26bhp or 12% from what she should have had new.
I don't expect a 12 year old car with 80k on the clock to still be showing 218bhp but this just seems too big a loss to be normal.
The guy was concerned enough to re-calibrate the dyno - same result and remove the air filters in case they were blocked. Same result. Full diagnostic check showed no errors.
He then spent literally hours trying to remap her. The best he could get was 200bhp an increase of just 8 and 13lbft of extra torque. This is someone who specialises in Mercedes and said that usually SLk320s come in with about 210-212bhp and go out with 20-25 more.
Does anyone have any idea where those 26 horses may have gone and how I might get them back again. With the remap if I can sort the problem I'm now looking at a gain of up to 40bhp if everything is back to how it should be.
I'll check and clean the EGR valve but there's no usual symptoms that there's anything wrong with it.
Blocked CATS?

Any ideas and advice greatly appreciated.

Thanks in advance

Steve

 

How do you come to get the crank hp?

 

Exactly. OP Customer may be confused about the reported dyno RWHP vs calculated BHP.

 

6 spd or auto, rwhp is where rotational weight factors in.

 

Throw a bottle of fuel system cleaner through it, you could well find a couple of horses there, I watched a test by 5th Gear on tv when they took 3 or 4 different cars with various mileages and tried to get them back to the claimed figures, the fuel system cleaner worked to varying degrees on each car, in one case the difference was around 5BHP.

 

Thanks for the replies.
When I was shown the graph on the dyno I specifically asked if it was rear wheel and was told "At the fly."
192 at the rear wheel would have been pretty good. If it's now 200 at the rear wheel then that would be somewhere around 235 at the crank which is ok.
I think I'll probably go somewhere else and get it checked again just so I know.

 

Just checked the Mustang Dynamometer website and it clearly states the dydno used measures RW hp. So using the rough 0.85 calculation we get 235 crank hp and 249lbft torque, which on an 11 year old car I'm pretty happy with.
I'll clean the EGR and put a few doses of fuel/injector cleaner through her, then get another check done just to be sure.

 

A step further would be to pull the injectors and send out to an injector specialist for expert cleaning and rebuilding. I just recently had this done; I think it was $22. per, so $132. plus $12.shipping.
Like you said; 11 year old car and all. If you haven't already done so; Plugs,wires,fuel filter, may be a good idea as well.

 

This thread shows some typical HP figures before and after a Eurocharged tune.
You will be surprised at the numbers.
CLICK

 

Sounds about right to me. I had my SRT version dyno'd two weeks ago and the print gave wheels and engine values, as the 'coast down' measures the drive train losses and adds them to the measured wheels bhp to interpret the engine power.

Mine is standard and gave 280.2 bhp at the wheels, 333.0 bhp engine with 305.0 lbft torque, giving 53 bhp drive train losses. Although mine is an SRT I would not expect a significant difference in gearbox and drive train making yours sound pretty good.

Cheers, Nick.

 

Torque converter, heavy driveshafts, u joint, carrier bearing, 29 lbs rear wheels.
All that rotational weight affects that 53 hp loss

 

that is incorrect.

349hp/332tq is what they are truly rated at.

SRT-6.com - Chrysler Crossfire SRT-6

Every dyno is different. Take it to the track and check the 1/4 mile trap speed to see how well it is running.

 

Been confirmed by the branch manager that it is indeed BHP at the crank, and when I put my glasses on and looked a bit closer at the charts it does say eng power and eng torgue, but having looked at the eurocharged dyno charts on here it seems to be pretty much on a par with those at around 170 RWHP/200 Crank HP
I've now cleaned the injectors and egr valve (pretty clean anyway) and swapped the oem air filters with BMC carbon dynamics, so it breathes a bit better. That's definitely made a difference low and mid range. Much more responsive now. Seat of the pants dyno tells me so, but also when my wife drove it, without knowing anything had been done, she came back and demanded to know "What have you done to "my car?" and why is it louder?"
So overall quite happy.
Now just need to make up some pipes and hoses for a full dual CAI instead of the air still going through the now empty original air boxes.

Thanks for all the help and advice guys.

 

Hi Steve, my stock n/a was put on a dyno last year it is a 2003 with 130,000 miles, pulled 208bhp if my memory serves me right.


Don't believe all the stories of unrealistic bhp gains you hear! lol if you want a fast Crossfire get a SRT-6, be far cheaper than what you will need to spend on an N/A to squeeze another 40bhp out of it (if you are lucky).
If you use facebook come and join UK Crossfire Owners Group, you will get advice and info from UK owners. :-)

 

Thanks for your reply.
I'm already on UK Crossfire Owners Group (Steve from Cheddar)

I'm happy with what I've done and at a reasonable cost of £250 all in. I wanted a bit more response in the low and midrange and I've got a not insignificant increase in torque exactly where I want it. Top end power which is never used is not so important to me. Totally agree re the fairy tale gains some remappers quote.

Cheers

Steve