Yesterday I went to a highly respected local tuner for a Golf VR6 owners rolling road day in my 2.5-16..

Here's my dyno run video:
http://video.google.co.uk/videoplay?docid=-5093045161667037144&hl=en-GB

and the results:



Top line is torque curve
Next line down is power curve

The markings along the bottom are:
100 = 3,700 rpm
150 = 5,500 rpm
200 = 7,300 rpm

Max power was apparently at 7,280 rpm!! I thought it was supposed to be at 6,200 on these cars?!
A bit disappointed with 186bhp calculated at the flywheel :/. Especially as I have driven this and a mint 2.3-16 back to back, and this is noticeably quicker (equally as quick as other 2.5-16s I have driven).

You can see a flatspot in the torque curve (top one) which is at 3,500 rpm.
I know I have poor compression and need top end rebuild - does that explain the loss of power?
What about the flatspot? It is very noticeable in daily driving and I knew it was there before hitting the dyno. I don't know what to do about it

help!

Russell

__________________
190E's:
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black 2nd owner
http://www.maylane.demon.co.uk/190esmall.jpghttp://www.maylane.demon.co.uk/190esmall2.jpg

The 2,5s aint referenced at 6200,the 2,3s are.

None the less..
The "bump" in the torq curve and the fact that you get max power higher than OEM ref and the fact that the power No is a bit on the low side..

My first check would be camchain.
Or..check..to hell with that,iīd just swap it and be done with it already.

Very interesting - why camchain? I have to say I don't know if it has been replaced so maybe it could do with it.

__________________
190E's:
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black 2nd owner
http://www.maylane.demon.co.uk/190esmall.jpghttp://www.maylane.demon.co.uk/190esmall2.jpg

Basic conclusion as far as iīm concerned.
1/The KE-jet is dumb as a doornail.
Ie;the closed loop work it DOES perform is in the lower bracket of engine work.(Late engines with O2 only btw)
That means that at WOT the KE-jet runs on predetermined values and that it canīt compensate for engine wear and tear.
2/You max out higher than the OEM numbers as far as where in the rev band.
We know that by RETARDING(delaying cam events vs the crank relative position) the camshaft events we will move the power band upwards.
We also know that by doing so we let off cylinder pressure-hence bad mid and low range numbers.(Torq is to a great extent a function of cylinder pressure-or more to the point traped cyl press)
As cam chain stretch becomes more and more over time-we will not only affect how the cams work against the crank,but the stretch will also affect whatīs called LCA-or Lobe Centerline Angle.
Any and all changes in LCA will have tremendous effects on engine behaviour as well as total rev range and torq.
The more stretch that occurs the wider the LCA will become-and sooner or later the engine will feel like its a damn rubber band and that i lacks punch in a severe way.
Stuff(wear)..the KE canīt compensate for either.

Iīve changed a chain or two by now on the cossies-and the funny part is that most people do this on the 2,3 out of fear that the chain might break.
The thing here is..LONG b4 weīre nearing the mark where itīll break weīve lost performance in a major way as described above.
Just did as a matter of fact on cust 2,3 and a guestemate is that the engine picked up around 10 horses.

Well that does make a lot of sense to me

I am also going to try the steps of cleaning off all the boards and connectors on the ECU, fuel pump relay and OVP, that were posted on mercedes190.co.uk.

I will get chain stretch measured.

Thankyou

__________________
190E's:
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black 2nd owner
http://www.maylane.demon.co.uk/190esmall.jpghttp://www.maylane.demon.co.uk/190esmall2.jpg

Kent cams sell a plastic,inexpensive degree wheel.
You need to cut it up a little tho.
Just make a couple of "stands" from some 10mm inner dia piping annd dismantle the crank pulley.
Find some M8 bolts thatīll fit through you now cut out degree wheel,and that are long enough to make the degree wheel stand free of the water pump.

Bolt degree wheel to crankshaft dampner per above.
Use some sort of wire and another short M8 bolt..twist wire into a loop and bolt to the "free",unused" hole to the upper right of the dampner-just below where the distributor is at.

Take valve cover off.
Bring out a 10mm plunge dial indicator.(1/2" works as well)
Register against the lifter cup and start by indexing the degree wheel at the bottom against TDC.Mercs OEM markings are usually on the money.
Turn engine over and check for maximum lift.Write these values down.

Ad highest point of intake in crank degrees to highest point of exhaust in crank degrees and divide by two.
Thatīs your LCA.