I get many calls each week about Dyno Power Pulls after remapping,mostly diesels and mostly because they feel the power they were promised is not there,So here is a totally standard C5 HDI book hp 136hp and after 40000 miles and many years of the school run it made 129.5hp. The problem is when people have complained to the remapper about the lower power output yes you guest it the remapper blamed the rolling road for the low readings. I do a special deal for people wanting a before and after PowerPull £60+vat for the 2 session on the rolling road.

Rolling Road check list plus terms and conditions

Treat a rolling road appointment as if you were taking the car for a MOT or to the race track , Silly things can really slow the job down which in turn could cost you more money.

Pre-Dyno Checklist
DO NOT bring a car with low or no oil pressure.
DO NOT bring a car with excessive mechanical noise.
DO NOT bring a car with any engine check lights on, I will not put it on the dyno.
Is the car leaking oil excessively ,small drips are fine.
At least half a tank of fuel.
Check the throttle cable and linkage, are you getting full throttle?
Check the tires for splits or damage, no remoulds allowed.
Check all wheel nuts, cars with loose or missing wheel nuts slows the job down.
Is the timing belt installed properly?
Have you pressure tested the intake system to check for boost/vacuum leaks?
Are the plugs new, proper heat range, and gapped properly?
Are there any exhaust leaks?
Is the cooling system in good condition?
Are the plug wires new?
Is the fuel system adequate (pump size, injector size, fuel line/filter)?
How long ago was the fuel filter replaced?
Is your boost controller holding steady boost?
Is the motor in good mechanical condition, what is the compression?
I suggest you complete a compression test prior to your tuning appointment. Typical compression test results should be as follows:
8:1-8.5:1 compression: 150-170 psi per cylinder
8.5:1~9.5:1 compression: 170-210 psi per cylinder
9.5:1~11:1 compression: 210-275 psi per cylinder
11:1+ compression: 250+ per cylinder (highly depends on cams being used)

Dynamometer Performance Testing
Terms and conditions


1. Control of the vehicle will be handed over to the Dynamometer operators

2. All care shall be taken,however,NO responsibility will be accepted for any damage or mechanical failure resulting from any activities with the chassis Dynamometer or the Dynamometer operator.

3. The vehicle owner/agent warrants that their vehicle, is in a safe mechanical and roadworthy/Race condition to withstand peak loads during the run on the Dynamometer.

4. John Sleath Race Cars Ltd . and the Dynamometer operator reserve the right of refusal to any vehicle.

5. By using/booking the dyno you indemnify John Sleath Race Cars Ltd., their respective Management,Staff,Employees,Operators,Volunteers and Sponsors against any/all claims, actions, demands, losses, damages, costs and expenses whatsoever suffered from or incurred as a result of the above mentioned activity.

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