Originally posted by mannyo in this post

Chris, When TaviaRS still had his superchip and I had been jabba'd mine was noticably quicker in the acellaration game. Of course that's not the case now.

It's a lot quicker now.

Des

Due to enormous pressure from Denis I've booked in at Noble Motorsport in Chesterfield. Monday the 13th October. You'll just have to be patient.

Also, Forge DV fitted today. It's very nice.

While we're on the subject, do Jabba charge more to do their magic on a 4x4 than they do an RS?

So this is how Jabba gets 230 bhp out of the K03 sport turbo!

Claiming 20% loss from engine to wheel is wrong, the accepted

figure is 12%. Now you Jabba boys only have about 205 bhp!

This makes more sense, please change all your claims soon.

/Eric

Originally posted by Eric_R in this post

So this is how Jabba gets 230 bhp out of the K03 sport turbo!

Claiming 20% loss from engine to wheel is wrong, the accepted

figure is 12%. Now you Jabba boys only have about 205 bhp!

This makes more sense, please change all your claims soon.

/Eric

Oki Doki...

from MY dyno plot...

Engine Power 171.8kW (233.4Cv)

Wheel Power 155.6kW (211.5 Cv)

A difference of 16.2Kw (21.9Cv)

Considerably less than 20 % i do believe

I was a bit provocative to get the discussion gooing ;-)

The 4X4 Haldex system only sends power to the rear wheels when front wheels slip, is this

the correct understanding? If so the driveline loss should be almost equal between vRS and 4X4

on a rolling road.

Eric R,

For the sake of all us non-JabbaDabbaDoobies, tell us more! Much more!

Eric,

Having just checked Denis's measurements from Jabba, i now see where your 20% figure comes from.

Whereas i don't for 1 minute dispute Jabba's figures, it would be interesting to know what the reasons for the difference in losses are.

We're not in danger of my graph being worth more than Denis' are we?

Originally posted by rich1068 in this post

We're not in danger of my graph being worth more than Denis' are we?

Good manners prevent me from posting the reply i was thinking of

It would appear that the 4X4 loses more in dissipate power ie from engine power to wheel power . Denis's engine power starts at 230.4 BHP down to a wheel power of 183.7 BHP , a loss of 20.2% .

Whereas on my car the engine power starts at 227.7 BHP down to a wheel power of 207.2 BHP , a loss of 9% .

(The was intended as a reply to Monkey Hanger not Mellow Yellow.)

Originally posted by rich1068 in this post

We're not in danger of my graph being worth more than Denis' are we?

It looks like it

Besides as Denis would say ...............if you've got it flaunt it !

Would it not also be reasonable to assume that the front wheels of a Haldex 4x4 would slip on the rollers, thereby sending drive to the rear wheels too, and bringing the additional losses into the equation ?

I'd certainly expect some wheel slip on a fwd car, unless the old trick of 2 or 3 people standing on the bumper was used

I think we ought to stop now. We're going to get so done when Denis comes back.:nono:

Originally posted by Eric_R in this post

I was a bit provocative to get the discussion gooing ;-)

The 4X4 Haldex system only sends power to the rear wheels when front wheels slip, is this

the correct understanding? If so the driveline loss should be almost equal between vRS and 4X4

on a rolling road.

Remembering that on a RR, the front wheels will appear to slip as the rears won't be moving.... The RR does'nt turn it gets turned.

It is'nt hard to imagine the front rear drive is haldex driven under these conditions.

Bill

The dyno plot for a 4X4 - as Fabpreza will confirm - is very jagged in appearance since the power is constantly being transferred from front to rear and back due to any wheel slippage detected on the rollers - and there certainly is when the car is tuned! Mike at Jabbasport does not publish dyno plots for the 4X4 because they need to be interpreted with caution and, I guess, knowledge of what is happening on the rollers. But I would remind sceptics that the 4X4 has proved to be more tuneable in standard form than the RS - something to do with the exhaust, I believe - and there were no caveats from Mike about the power increase achieved on my car. I don't have the knowledge or facts to get involved in a debate about transmission power losses other than to say that in normal driving I would not expect the losses to be significantly greater than those for a FWD car. But I do know which car can get that power onto the road more effectively once the wheels start spinning - and it ain't an RS.

Please carry on with the discussion, chaps - I'm quite enjoying it!

PS Bill is correct in saying that both sets of rollers are driven when the 4X4 is tested on the RR. The noise and vibration when both sets are turning is pretty horrendous and the whole building vibrates.

But I do know which car can get that power onto the road more effectively once the wheels start spinning - and it ain't an RS.

OK he's taken the bait ................now let's reel him in

Originally posted by DGW in this post

But I do know which car can get that power onto the road more effectively once the wheels start spinning - and it ain't an RS.

And i know a car that's not at the limits of its brakes and suspension after a re-map, and it aint a 4x4

Originally posted by mellowyellow in this post

OK he's taken the bait ................now let's reel him in

Ahem...

I'd just like to say that was a very well argued and reasoned post from Denis. Most of the technical issues regarding the tuning of a 4x4 were touched on and I welcome his balanced input but...

whoah! Fishy! We've got a live one! Lets see if we can land this one!

I am currently watching Jaws 2..

Here fishy fishy !

Originally posted by rich1068 in this post

We've got a live one! Lets see if we can land this one!

I'd like to think we could ..............but Denis probably won't bite anymore ...........he's a wily old fox ........................and anyway he knows when he's beaten ...........isn't that right Denis ?

Originally posted by mellowyellow in this post

but Denis probably won't bite anymore ...........

Well, not tonight at least