NA motor builds?

[Tubby]

So I just purchased my first Audi, a b7 RS4. I came from owning VW's my whole life and frankly . . . . I'm never looking back, this car is just incredible. Now to the topic . . . Has anyone done anything past the usual exhaust, tune stage? Im really curious what these motors can do when built right. I'm talking about gains from spacers, camshafts, lightened pulleys, deleted flaps stiffer motor mounts, custom tunes ect. I haven't been able to find much but I would like to know the possibilities of doing all the above to see this thing become more of a beast without forced induction. Cheers

Any suggestions with proven power gains would be great along with where to pick up any of the parts.

[rwilsonrs4]

dont think theres much more internally that can be done with these motors , the work and effort audi put in to these things comparesd to the normal 4.2 in say the q5 was huge , MRC do the de flap and manifold mods and custom mapping which is the best way if you want to stay NA .
whole bottom end is forged so nothing to do there , the only possible thing may be different camshafts or bigger valves /porting but that would cost the earth , unless you havs a spare motor and get the heads done properly but i dont know of anyone who has even done head work on these or developed cams ,
For supercharged applications maybe a better cam may be an idea but i think a lot of development would be needed
Just supercharge it , they are bulletproof motors mechanically

[Tubby]

Thanks a bunch, would you happen to know of anyone in the US thats on par with MRC for that kind of work? Also, are there any issues when going header back large diameter cat-less exhaust, my concern is the back pressure on the NA motor.

[marc1]

Loads of info on this forum and the net in general buddy. Most US folk seem to favour JHM, who do supercharged and maps to support them. They also do 2.75mm diameter exhausts as claim they give the best gains.

[marc1]

Oh, and get some pictures up of the new beast.

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Thanks a bunch, would you happen to know of anyone in the US thats on par with MRC for that kind of work? Also, are there any issues when going header back large diameter cat-less exhaust, my concern is the back pressure on the NA motor.

you are unlikely to get masses. removing the cats can help alot with the right mapping but with n/a you can go too large. its all about gas velocity and the wider the exhaust the slower the gas moves. its a balance between the gas slowing due to back pressure or wide pipes.

problem is that its a compromise - exhausts optimised for top end power tend to lose out lower down as at medium rpm the pipes are oversized.
get it sorted for the mid range (which is the norm for oem) then the back pressure causes issues at high rpm.

overall though the engine can be made quite happily to get in the region of 450 with the common modifications and thats operating at over 100hp/litre.
even stock, volumetric efficiency is over 100% so again it doesnt leave much to improve. i dont think there are any after market cams as this would be the nexet logical step.

[Tubby]

Will do once I get her all dolled up and shinning bright. Thanks again.

[rwilsonrs4]

never realised you were from across the pond , yeah JHM seem to be the most popular over with you , bigger exhausts dont seem to be much of a benefit apparently 2.75 seems to be the max but lose torque , but even with minimal benefit the noise is much better the headers are already as good as can be for this engine without internal mods/ cam changes etc, different custom headers have been tested on a forum members car and i think it lost power , prob due to the cams , good luck with the car , think youll migrate to Supercharging if funds allow , transforms the cars

[Tubby]

Right on, so for the most power gains through exhaust without losing anything and keeping adequate back pressure would you recommend just the 2.75 catless downpipes with stock catback or just go 2.75 the whole way back? The sound to me is just a bonus, im focusing on squeezing as much power as i can out of it before i have to drop serious cash on FI

[Tubby]

im looking at stiffer mounts, lightened crankshaft pulley, exhaust, deleted flaps, port and polish all tied together with a custom tune with a fresh carbon clean of course.

[rwilsonrs4]

well there are a few different ones out there , but miltek is popular over here and is the same as OEM 2.5 inch and doesnt really give power gains to be noticed most fit them for the noise ,i dont run catless but have just 100 cell main cats and full miltek
JHM is popular with US cars and for you will probably be the easiest to source , i have done a fair bit of headwork over the years on various engine projects and looking at the heads on the RS4 there is some mild improvements could be made around the back of the valve throats and the seat area with some 3 angle work and blending of the machining ,I dont know if bigger valves are available easily so might need to be custom made
If i ever aquired a spare motor ( doubtful ) i definately would pull the heads and do some work , but the inlet manifold is where gains can be made easier , deflapping it and removing the big hump in the tract flow gains can be made there but will need remapped to remove the sensor issues that will occur when this is done

[Surrey Sam]

Cams, Single Mass Flywheel, Knife Edging the Crankshaft and a Re-map would be my suggestion. Still not worth the cost of doing compared to a forced induction setup.

[Rick_RS4]

deflap, exhaust, no cats if possible, remap, maybe lw flywheel

do carbon clean before the map as they clog up quicker than you think, but then stay at a certain evel of buildup i have found

thats all id do unless you charge it

[ginch]

What do you guys mean by de flap? Do you mean removing the flap in the airbox?

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