My son and I have 2 of 2003 MCS with JCW and 210HP Upgrade.
Both cars are identical to every detail .
We are about to add some stuff to increase HP. To get a base line we Dyno both cars and
get 192 HP (167 whp) and 190 HP (165whp). Both cars should be around 210 HP... right ???
The only change we done to both cars was to fit the Magnaflow exhaust about two years
ago. Do you guys think this is the reason why we lost about 20 HP ?
Agreed, 192bhp for my 210 when it was dyno'd as well. Most likely the airflow through the scoop.
As the supercharger spins up, and you reach higher revs, the air being pumped by the supercharger gets heated by the compression - opposite of how a fridge works! - and this heated air is far less efficent than cool air for producing power. The point of the intercooler is to drop the charge temperature of this heated air. Obviously, the intercooler only works efficiently when air is being forced into the intercooler - on the road at speed!. Also, the engine bay heats up on a roalling road unlike on the real road, and this heat soak makes the engine also perform less well.
Another thing that can sap power is the size and weight off the wheels that you have fitted. Got flashy 18" wheels? Well, it saps more power to turn heavy wheels. So, to get a good dyno figure, take along a set of lightweight 16" wheels, fitted with some performance tyres, and you'll probably get a few more bhp. A good trick that is used by some tuners to 'exagerate' their bhp figures is to over inflate the tyres. Running 50psi will give you another 20bhp or so!!!!!!
If you ran the same car on half a dozen dynos, you'd get a slightly different result on each. Air temperature, air pressure, humidity and other factors also play a part..... when BMW test their engines its in a laboratory test bench. Every thing is controlled - and you cant possibly recreate this on a rolling road.
All this said, many people think that BMW sometimes over exagerate their output figures, and that JCW horses can either escape or are just plain a bit 'lazy'....
The best dyno by far is the butt dyno. Get your mods done, then use the butt dyno to test the upgrades. Does the car feel more powerful ? then thats a success....
Hi, what Tony says except the Flywheel figure will not (should not) be effected by gear/wheel size/ tyre pressure etc, the F/W figure should always come back to the same figure. The Wheel Horsepower (WHP) will change with different tyres/geat/pressures though, hence the importance of MEASURING the losses and adding onto the WHP figure, to get the much more important (and comparable) Flywheel Horse Power.
Most JCW210's seem top come out 190-200bhp, which at £3500 is bordering on criminal IMHO.
Best Regards Roland GTT
Just some more information, when we dyno both cars, the Engine temp was
about 165 - 175 deg F. the ideal temp. According to the Dyno tech people the conditions were ideal.
We also placed a large dyno fan aimed at the SC opening to simulate
normal driving conditions.
My opinion, one can expect a variation on dyno figures due to a lot of factors,
but 20 HP is a bit much. At least none of you think is the Magnaflow exhaust,
if anything should have improved it by at least another 5HP .
I feel like asking BMW what they think....well for now I will keep my thoughts to myself. But later???
I think Roland had the answer with most JCW cars come back from a dyno with with a figure close to yours! i would think BMW have over quoted the HP figure. the Exhaust will have probably made the setup better as the JCW exhaust that will of been fitted is quiet restrictive as far as im aware from Rolands testing figures the JCW zaust was the worst if im correct!
Don't be confused, because you simply cannot compare Rolling Road figures, as they differ from one run to the next and from one operator to the next. If cars are done on the same day, in the same conditions at the same place then at least they give you some comparison, albeit never completely accurate.
I'd be interested in seeing the results of a few cars done together, so a standard s, jcw, tuner x etc.
good points, but how do we know that the RRs that give a standard s 190 aren't way high? Also, maybe a JCW only actually makes 200bhp, and the RRs where we've heard of JCW making 200 are actually quite acurate?
There's one thing for sure, a standard s isn;t gonna make a real 190bhp and a JCW IS gonna make more power than a standard s. Who knows what other factors are involved too, - it's just a lottery.
I'm gonna do some more searching to see if there's been a good array done on the same day for comparison.
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