Thread: Had the 3.9 RRC dyno'd today

Originally Posted by PhilipA

I took my 92 RRC to Autotech in Sydney today to have the Unichip fitted by Graeme Cooper about 5 years ago checked , ...

...Anyway the owner Spiro looked at the Cooper settings, reckoned they were crap and started again. ...

...To be fair he did invite me to sit in the car on the dyno and showed me the Cooper settings on the laptop compared to his and why Cooper's were wrong etc. ...

I think you are being rather unfair on Cooper's with your statement about being crap, over time the general condition of your vehicle will change as will the settings. Isn't this why we get them tuned regularly?

More than that any competent dyno operator should review the settings and start afresh.

I took my RRc back to Coopers today to have dual mapping activated in the Motec ECU to run LPG and even though they installed and tuned the system over time the performance has fallen off.

Like your Autotech mob Cooper's have been able to get an increase on my vehicle and yes they performed the operation in 2nd.

Dyno graph on petrol.



Dyno graph on LPG.

Originally Posted by PhilipA

... I cannot reconcile the Cooper and Autotech graphs as Cooper took them in second and Autotech in third. Cooper shows almost 80KW while Autotech shows a max of 68KW, up from about 58Kw before changes.

This is to be expected with 2 different dynos. I sometimes wonder if the shootout mode on the dyno understates the starting run>LOL.
BUT I cannot argue with the very obvious increase in power. ....

Have to agree with you about the performance improvement and wonder about the dyno understating the initial test, but why would they bother?

Would you be able to reconcile the graphs by working out the relative speeds in the different gears then shifting the graph to corellate with the calculated speed/gear?

Am still very happy with Graeme Cooper Automotive. Have been one of their customers since 1988 and will continue to use them.

Diana

P.S.

Originally Posted by POD

Maybe by this time next year!

Pod: Oops - missed your point about my missing the point, but what ever the point let us hope that fuel doesn't get to the $200/litre point!

Did they tell you why they dyno in second? I would have thought 3rd would give a more accurate reading being closer to a 1:1 ratio,
Dyno'ing in second would give a higher HP and thus torque reading as the dyno would ramp up quicker.

Im not critising Coopers or your tune i just wondered with the carry out the tune in 2nd gear?

Originally Posted by Lucus

Did they tell you why they dyno in second? I would have thought 3rd would give a more accurate reading being closer to a 1:1 ratio,
Dyno'ing in second would give a higher HP and thus torque reading as the dyno would ramp up quicker. ...

Lucus

I have no idea why they do it in 2nd and you are possibly correct about ramping up quicker. It may be something to do with an auto transmission 2nd being roughly equivalent of 3rd in a manual, however having seen and heard vehicles on the dyno I can imagine it could be a safety or noise polution issue. The last thing you would want would be two tonnes plus of RRc taking off at full pelt into Princess Highway without a driver if one of the straps broke.

What I would also summise would be that the performance curve would be quite similar whether done in 1st 2nd, 3rd or top, just the speed would move along the horizontal graph.

What I can do is ask the question when I go in there on Thursday to pick up a part.

Diana

Manual are generally done in 4th as this is 1:1 and the only torque mulitplier is th diff ratio.

If i recall correctly 3rd is 1:1 in a ZF 4 spd.

Most dyno's top out at around 180 to 200kph so a range rover spinning up too 150(ish) in 3rd wont worry it. Generally if a car does break straps they dont leap of and shoot down the road and full speed as the have Zero interia and momentum. You would be picking bits of engine and driveline off the workshop floor.

I have seen and inter truck jump off a dyno at full tilt. It screwed the driveshaft off the diff,bent the trans out put shaft and twisted the diff on the springs, it only move foward aprox 5 metres though.

Dyno'ing in second will give you a higher peak power reading but as your only using the dyno as a tuning tool the acutal number isnt the issue its the average power under the line and how much it increase after the tune.

93kw is pretty impressive for an LPG engine! what model motec are you running?

Lucus

The Motec is the M48 but it isn't one with logging and I'm unaware about the software version. It hasn't been changed since install in 1997.

B.T.W. you are looking at the petrol graph (on E10 petrol - BP91) the LPG graph is the 85.4 Kw.

Diana

Ok okay.....85kw is still bloody good for a lpg engine. Injected or vapour?

9% power difference between LPG and petrol is pretty Goes to show what a bit of timing can do for and LPG engine

Lucus

It's a vapour system. With the price of petrol these days I'm very happy with the conversion and haven't had the problems that some people have had with the LPG injection systems. Nor have I had any backfire problem as I don't use the MAS of the standard systems.

Getting the dual mapping enabled to switch as I change fuel through the Motec ECU should make it that little bit better again.

Diana

So does anyone know what driveline loss a rangie has?

I dyno my diesel 3.9 rangie up a viaduct which I know the exact slope of. From this I know I've got 74kw at the wheels at 2000rpm. That's manual in 4th (1:1), an LT230 with the 1:1.003 high range and 225/75R16 BFG AT's.