RS4 600BHP from Digi-tec

[Anonymous]

http://wwwstud.fh-zwickau.de/~ao/digi-t ... di_rs4.htm
This looks pretty impressive and an alternative to MTMs 600 Bhp flagship
Cheers
Jr

[johneroberts]

[johneroberts]

[Joshie]

That is really impressive acceleration - 0 to 125MPH in 12.5 S.

But does it strike you as being just a little on the pricey side at c £80K?

[johneroberts]

£80K whats money when you got piles
Cheers
jr

[Andiroo]

Still dont understand where 600bhp comes from. OEM intercoolers, OEM airbox, where does the heat go?

Will it do 1k miles without melting?

Andiroo

[Bushy]

MMm

I thought that

The intercoolers and inlets look standard.

However the MTM upgrade to 600bhp doesnt mention replacing those either

[Bushy]

Mmm

Interesting that the top speed is quoted as 206.3, they must also have moved the rev limiter

[PhilT]

0, 60, 100, 150, 175, 206..... Kerrrrr BOOOOOOM!!!

[Bushy]

it does say in the small print, mmax spped is a one off experience

LOL

[Andiroo]

Unfortunately I've experienced that heat doesn't dissipate thru the exhaust tract, well most of it at least. The turbo cycle takes the heat generated in the combustion chamber and just flows it back thru again. The most effective component is the cooling ie. intercoolers, followed by heat soak resistant materials around them, followed by some form of charge cooling (not water injection). The temperature of the air in a charge of combustable fuel is critical for bhp and torque, and the ability to sustain those readings in everyday driving and trackdays. This is why most individuals first rolling road plot generates the best figures, the heat just cannot escape.

Dont get me wrong, these guys (MTM and Digitech) will probably get these figures once (fuel is questionable as is peak boost), but once heat soak occurs either on the RR or on a trackday, their customers will be looking for a)a fix for the front bumper that appears to made of chocolate buttons, and b) a distinct lack of bhp followed by the engine management light staying on.

Tests pre and post Sportec intercoolers showed a variation of 16c in inlet temp, and torque jumped 40nM - sort of shows what can be achieved.

A full detailed report of the charge cooling will follow in Feb, when Scott gets back, along with the results of fully modded turbos (not bigger, but better flow @ 285bhp each), intake manifold, exhaust manifold and carbon airbox.

Any further ideas re anything that will help my quest would be welcomed (we are already looking at copper piping for the IC's, and as soon as the nations NOS expert can explain why he would fit injectors before the turbos rather than at the throttle body , maybe even this)

Tip of the day - RS2/4/6 tuning - dont make it up as you go along, follow the Skyline GTR's - their experience has a lot to offer based upon a similar setup.

Andiroo

[Joshie]

===========================================================
RS2/4/6 tuning - dont make it up as you go along, follow the Skyline GTR's - their experience has a lot to offer based upon a similar setup.
===========================================================

So do you have any links to what has been learned from the Skyline Mods?

[Andiroo]

Hi mate, here's one reply to several questions I've raised;
----------------------------

Interesting.

This is prompted by Mr Law's need to mitigate some of the detrimental effect of his very high under bonnet temps.

Water injection in the inlet plenum is very awkward to map and needs frequent refilling, great for the dedicated track car a pain for a road car.

Spraying onto the side mounted ICs' will work if controlled by sophisticated timing works and gets rid of the heat usually not into the engine bay, which is the goal also as this lessens the heat soak into the bay. An FMIC will not help in this last case as any heat given off will just be poured into an already overheated engine bay and lessening the effectiveness of the main engine cooler, the radiator.

There is some value in injecting some water in the inlet tract prior to the inlet air entering the compressor housing, this is very good at dropping 20degrees off the output temp. however you need quite short inlet runs and it must only work above 10psi so as to avoid condesation problems, a bit like driving in torrential rain, the car may splutter on backing off.

The best plan is to use the second of these options, and then deal with the heat build up problem, first you have an outside air intake (if not why not?) the air must contact the face of the filter as cold as possible it must never be warmed, no warm air from the engine bay must be allowed to enter the inlet tract, once past the filter this cold air must be conserved, so insulating pipes and pods is essential, the air must not be heated before it enters the compressor, now look at you exhaust system, and whilst you are at it, you must insulate the headers, NOT the turbos, thats fro racing cars only, insulating the headers after the turbines will lessen heat soak and give you about 3% more torque, be sure to carry the insulation as far along the exhaust as you can, within a foot of the cat is very good indeed (dont insulate the cat as it will over heat and the platinum catalyser will luxate into the substrate and you will be left with a dead cat. The air flowing from the compressors must be allowed to 'vent' into the engine bay it will be pretty hot at elevated pressures say 110-130C so let them get rid of what they can, use some copper to 'soak out' some of this prior to the IC.

The following is subject to verification next month: After the IC copper can be used to again to 'even' the system out .

Other things to help any car is to utilise the badly named venturi effect of some boy kits, as I had access to an Air Tunnel recently I tested a very simple side spat that i had designed for my car, the effect on flow into and out of the engine bay was that 15% more direct flow occurred, my car is very 'slippery' so this is a good result, the cost of the parts amounted to just £105 and are very discrete. I'm sure the effect can be replicated on any car.

Courtesy of Mycroft, GTR register - August 2002
----------------------------------------------

Just seems some of these guys understand more of the physics that's involved in cooling a high bhp motor, although as yet only a couple of guys with R33's have tried misting sprays on IC's, and no-one as yet copper as described above.

Luckily for these guys they dont rev as high as us, or generate the torque so low down the rev range, so heat isnt so much a problem as it is for us. Even so they have some really clever ideas which, in principal, we can apply.

What do you think?

Andicopperoo

[Reno]

This is very interesting, since I always wondered how tuners like MTM managed to get 600hp with (at first sight) minimal modifications. (i don't know a thing about car-technic, so it's possible that the things I ask are stupid )Do they change the clutch and gearbox as well? I don't know how much torque the gearbox of the RS4 can handle, but i've read that audi has chosen an automatic for the RS6, because they don't have a manual gearbox that can handle more then 560 Nm, so assume it will be less then that. What about your cars? For example, I see that the john robert's car has 648 Nm. Thanks in advance.

Greetz

[Andiroo]

From what I can gather the mods are.......not much really, which surprises me.

Intake manifold, bigger turbos, possibly pistons and headwork - racing clutch but no mods to the gearbox. The gearbox is one of the weak links I'm very concerned about, especially now that she should be touching 550bhp/680nM in about a months time No noticeable work to the intercoolers or airbox, so that thing must get rather hot (same as the MTM I would think).

I found I had trackday heatsoak problems with only 466bhp most of last year, till I got the uprated intercoolers, now she seems OK

It will be interesting to see the rolling road temps around the inlet charge when she's finished (with and without the water injection), to give some ideas as to the problems these guys are having.

Andiroo