Dest's S2 Avant

[S2central.net]

@dest - get some sound of that ting up on youtube please.

Is it 'boomy' on the motorway or cruising at steady speed ?

My zorst is on last legs and I would like to do a special stainless system as I can legally decat here.

Thinking of Supersprint downpipe (70mm) and then 76mm straight to a Milltek rear box. Think I need to squeeze down to 70mm for the rear driveshaft clearance... Actually maybe 70mm all the way is cool enough - I wont be limiting anything in the foreseeable future.

[Rusty]

Paul, I'm looking at 3" turbo to centre box and then 2.75" back. Was speaking to the chap I want to do it the other day. Just got to sort this Milltek mess out first and then I can finally get the car sorted. nice and loacl to me but not for you unfortunately...

[dest]

It is quite boomy when cold, it seems to quieten down abit once warmed up.
Remember it needs to get coked up abit yet though, so that might change things abit.

Worth noting that it was fairly boomy before too.
It is mainly when driving in town, or holding in gear below 3k. Soon as you get cruising its not really much louder than the original system.
I will get some clips up, but my camera doesnt like picking up low frequencies, so you seem to end up with alot of tyre and wind noise!

[s2driveruk]

looks fantastic, would be interested in hearing it too.

@ Paul you can legally de-cat and you haven't yet? wish I could!

[re2500]

s2driveruk: Why cant you legally decat? '92 is before the cat requirement date isnt it??

[s2driveruk]

nope......my car is registered on 4th August 1992 which means it's subject to the BET (basic Emissions Test) which means I need to have a CAT in place to get the emissions low enough to pass. 5 days previous and I wouldnt need one such is the stupid rules on these things. If it was on engine code thn it would make more sense but its date driven.

Likely that i will just replace my cats with a 1 x 100cpi cat which is almost zero restriction in flow versus the 2 x circa 400cpi OEM cats and is enough to drop the emissions below the threshold.

[re2500]

AHH, thats a bit of a sh***er.
A 100cell single cat sounds a plan TBH. Having a single cat will improve the sound too, the twin cats interferes with the off-beat 5 cylinder growl that we all love. Youll find that with a single cat (or no cat at all and a single pipe back) It'll sound more like a N/A 20v or 10v.

Im really surprised with my car, i went from a NA 2.5 10v engine (pretty raw sounding) to an ABY (no cats, single pipe back, same stainless system from 10v engine.) and the sound is hardly any different. I was worried it wouldn't sound as good. ABY is very slightly smoother. But maybe thats cos my 10v didnt idle for sh*t.

[s2driveruk]

must get my lazy *** into gear on this, Its the biggest drawback of the current setup that the offbeat 5 sound is so muffled compared to earlier 5 pots, even in 20v form.

I'm off next, week.......watch this space

[s2driveruk]

actually, got a clip of your exhaust sound anywhere?

[re2500]

I havent got a clip at the moment, i'll look into getting one posted up on the weekend.

[dest]

To counteract the thread highjackers, (only joking lads lol) the results are in!

As Paul kept saying, it has backed up that it definitly does have a boost leak.
It makes 1.3bar, exactly as my gauge said, and then starts to tail off at 4400rpm.

This is causing it to run abit rich in the middle, and then again towards the high end of the range.

Overall, Im quite pleased with the figures, especially the torque!

To summarise:
207.3BHP @ wheels
278.9 @ fly
315lb/ft

I will be looking into getting a set of silicon boost hoses asap, and also finish renewing the vacuum pipes too.
Any guesses as to what it would be running if the boost had held?
Current mods are:
Air box modded (Similar to Andy's)
Stainless system from downpipe back, no cats, with rear Milltek box
1.8T coils
Mark H mod
Homefry

[S2central.net]

Dest - that is NOT a bad looking plot...

True you should be more like max of 1.4bar - but you aren't miles off. Minor leaks, tired turbo, old wastegate can see to that.

Note the boost profile is supposed to drop off like that - its needed to keep air temps under control in that lil K24 turbo.

210bhp ATW is about right on a homebrew. You could perhaps have expected a bit more with the airbox and zorst mods - but thats probably a result of slightly less boost.

AFRs look good - its supposed to be between 10-12 at WOT for a nicely rich mixture - not too rich.

Your torque in the mid range is mighty (that 424Nm) but the power at the top end seems to suffer slightly as result of lil air leak.

[dest]

So all in all, not too bad then really
I will definitly get all the pipes sorted, just so I know they definitly are ok and not leaking.
Driving there this morning it definitly felt like it pulls better since the cats came off.
Once its on the move in 4th or 5th gear it pulls like a train even in 6th cruising at 70-80 then flooring it, it picks up well!

Going back to the exhaust noise levels, now I had some time away from the car when it was just done yesterday I got to experience it with a less biased pair of ears this morning
Starting from cold its bloody loud!
As it warmed up abit, it got alittle quieter, but is still rather raw and raspy at low revs.
Sitting anywhere between idle and 3k on the move and it is very boomy, but not alot more than it was before removing the cats.
Anything over that when cruising along its got a nice deep note, but not too over powering.
On WOT it sounds mental!

So, for an every day car, it definitly would become abit annoying rather quickly, as it is very intrusive at times.
As I dont drive it every day, I quite enjoy it TBH

[Fat Audi 80]

Great result Martyn!

[A80Avant]

i see...so the cats remain on mine..