(R)S2 coupe to 450HP

[A80Avant]

my downpipe was 80mm eventually,twin catalysts(new non original) and milltek catback.Sound is quite base,but i would like it a bit less loud.Milltek tend to be loud.

[Greg_S]

Does the twin exhaust of smaller diameter along the centre of the car reduce exhaust boom?

[mastermind]

I'm not sure whether twin or single is more boomy, so would realy like to know what others feel maybe I should ask this in the exhaust section of the forum.

[A80Avant]

i think the sound is mainly due to the tanks not the size of the tubes.Lighter tanks,make more noise and on certain rpm when there is resonance with the rest of the chassis.Miltek tends to produce more sound around 2000-2500rpm and then becomes silent

[Greg_S]

In that case the smaller pipes must be mainly for clearance then. Think I may need to get mine tweaked a bit since it is boomy between 55 and 75

[mastermind]

exhaust

I had an RS2 Avant which was quite boomy at around 4000rpm, avants carry alot more sound into the cabin than coupes.
I eventually changed the middle silencer to twin 56mm inlet pipes (it was 63 dual all the way) and what this did is it changed the frequency of the sound traveliing through the system and in effect workeed to try and cancel the sound wave initially travelling through the system. It cant obviously totally cancel the sound as then we would have total silence...almost what New Car R&D engineers try to obtain using millions.

This also causes restrictions which means 0.001% less power.. ok maybe not as small a drop, but you get my point. If you need it to quieten down, there is a compromise, which is normally a small price to pay in a road car.

Which is why I need to investigate how much power/torque the bigger diameter down pipe is going to give me, if I keep the setup of silencers on the car currently and not change the whole system to a single 76mm Pipe.

[A80Avant]

In my case which i think im at either 76 or 80mm pipes from downpipe to the back(except the part where there are the 2 cats),i believe that my only solution is to change to less boomy resonators.I get the boom on around 2000rpm and it is nice after that.Around 3000rpm where there is the cruising speed in trips,it is OK.

[mastermind]

The Red Baron has now done 250km after the upgrade and alls well.
Here are some pics of the installed. The idea was to keep the car looking as stock as possible, except for the silicone hoses of course.

[mastermind]

The airbox had to be moved slightly and the bigger MAF to Turbo Hose supplied by O34matches the Samcos very well.

[mastermind]

Closer look

[mastermind]

The next step after the car is run in is to consider a new down pipe.
We trimmed hot side of the turbo in order for the WG flexipipe to line up perfectly.

[mastermind]

The Red Baron is now run in and we have changed to Siemens 650 injectors and a Walbro Fuel 220l/hr pump. Which drew so much current it damaaged the circuit board in the fuse box, so we ran a new heavier duty cable with an inline fuse.

The fuel pressure regulator was adjustable on my car and was set to 4bar.

I now have a slight idling problem with the car. Hopefully Freiling Racing the tuners will sort it out soon.

The car boosts 1 bar at 3000rpm spoils lightening fast to 1.5bar at about 3700rpm then tapers down to 1.2 at 6500rpm.

Part throttle response (a sign of a good tuner) is excellent the boost is beautifully regulated.

AFRs are normally around 13.5 (amazing )with no detonation and just under 12 at peak boost.

EGTs stay under 700deg

As Javad said the end result is a very drivable car, imho far better that RS2 albeit 200 revs later boost.

More tuning will be done after I change the down pipe to 3" and remove the standard dual exhaust system and middle silencer that came with the car.

Those of you have more experience with AFRs and EGTs, pls comment on what your experiences are with these readings, and what you beleive ideal should be.

[GazzaG60]

looking good.

on mine i used a sc61 turbo a bit bigger than the 3071. i start to boost at 3k and hit full boosat by 4200 maybe a bit sooner.

afr's i run 1.10 at cruise and idle bout 16:1 s so fairly lean. this leads to quite hight EGTs but some timing will cool it. i get around the 500-720 egt so far. the 720 is at 80-90 cruising. i need to tweak the cells in this area with a tad more juice and some timing.

on boost i run around the 0.78 mark which is about 11.5:1 runnig upto 1.3 bar so far. dont think there is much left in the standard injectors. egts on boost are less than 700.

still messing but want fuel economy to an extent and i do better now than on the standard setup

exhaust booms at 1600RPM fells a bit flat at that point. otherwise seems good.

i have a 3" system but feel open dump would improve performance even at current stat of tune.

[A80Avant]

when posting EGT readings it is wise to state the location as 5-10cm difference may have 60-100C difference!!!
For example the EGTs i read are quite lower than mine.My EGT sensor is placed ON the hotside so the reading is as accurate as it can get.
On idle after a bit of thrashing i get around 520C and after a couple of ventilator runs it will cool off at aroun 490C.

Cruising speed of 100-120 on 5th or 6th gear temps are around 720-750C
Max temp on WOT is 900C to 920C.
when in use of WI then temps are around 820-850C on WOT

Tuner told me that 900C on the beggining of the turbo(hotside) means around 100C less on the usual location of the EGT meaning the beggining of the downpipe,so he said we are fine there.

AFR i dont have,but when we tuned it i stated that i wanted as close to λ=1 as possible on revs up to 3000rpm,just before turbo begins to build,so as to keep fuel consumption as minimal as possible.I don know the afr on WOT though.

boost comes on at about 3000rpm and i get full boost of 1.6-1.7at 3700rpm,then gradual drop to 1.3bar towards the red line.
Im waiting for the new eproms though for 1.9 and 1.5 figures...im going to have a dyno before and after to see the differences

forgot to mention,i never had any idle problems yet,besides the MAF needed to be replaced.We made the idle stable at 880-900rpm and it never stalls.

[GazzaG60]

probe is placed on exit of hotside at top of downpipe. i9 have wrapped header also.