Martin J Stirling

Had a turbo back, straight through 2.5" exhaust (inc. downpipe) fitted recently with no cats or resonators to my P1. Although I am delighted with the increase in performance and the accentuated Scooby burble, I am quite dissapointed that I don't get any flames or pops and bangs.

Can anyone explain this? Is it because my car is running lean or is it 'cause i'm using Optimax?

Any suggestions much appreciated.

Cheers,

MS.

Pete Croney

You will when the exhaust is very hot

Trucker Ted

Drive a wee bit harder and they will come....!

Unburnt fuel + hot exhaust = big silly grin.

JohnD

iTrader: (5)

Dont forget that on later cars the injectors switch off on the overrun,(then back on again at about 1300 rpm ready for idle) so although you will hear some popping, you probably wont get the effects that guys with earlier models get.
JohnD

Trout...

Believe it or not - Optimax will significantly increase pops and bangs!

Didn't used to get any with a Link and lost those multi-storey car park moments.

But it's sorted now!

Trout

Mr Footlong

iTrader: (7)

Hate to disaggree, but I get far, far less pops bangs and flames since swapping from SUL+Millers to Optimax+Millers


Nick

( There's always one )

Trout...

There is always one - and it's usually me!

By the way I have stopped using Millars with Optimax as it didn't seem to make any difference. But there again - that could just be me!

Trout

We have a secret plan to fight detonation!

Danny Fisher

Fishy, maybe you have just adjusted your map to run richer. This might also explain the extra pops and bangs your getting.

Dan

Gridlock Mikey

Dudes, with reference to the earlier post about the injectors closing on over run on the newer cars It is true, they do but , you can over- ride it by gently and quickly applying a tiny bit of pressure to the accelerator while the engine is over running.

So long as the exhaust is hot, i can make my scoob pop and bang to order Great for those bus stop passing moments and tunnels and multi storeys etc.

MIKEY

Tim Taylor

I agree with Mikey

I do the same on my RB5 to get those pops and bangs

Tim

Pete Croney

Or fit a VTA dump valve. The air mass sensor still registers passing air on over run and fuels accordingly.

Then this happens

[img]http://communities.msn.be/_Secure/0OgAeE*cUnFuwvWle7ua2Op8yua052cbOopMdqjIllG!6rRO9L fz4U0dhotLEfFaXOeTf6QwJhS5uCKkH8xtovXK4P0PBijZm/Flame2.jpg
[/img]

[Edited by Pete Croney - 10/26/2001 10:31:10 AM]

ScoobyJawa

lol@Pete

All you need is a few sausages and burgers and you can have a nice BBQ when you've finished the lap

Blackscooby

**WOW** How cool is that

MY UK94 has a VTA with a turbo back SS exhaust, and does pop and bang on the overrun, but no-one has ever told me it does that.....

Fantastic !

Pete Croney

This was my dutch dealers cars, at Zolder.

I went over to Abbeville in France a couple of weeks ago. Its a short tarmac sprint/autocross circuit. Because its a short "turn and squirt" circuit, the exhaust gets very hot. There was a short 2nd gear straight just in front of the main spectating area and it was giving nearly 3 feet of flame on lift off, for 2-3 seconds

Abbeville is a great fun circuit, as some of the bends are very wide and are coated in an ultra low grip tarmac. Full on autocross stylee, even in the dry

Trout...

Fishery,

we all know my map is much leaner now with the big O as the car is more efficient

Fish Boy

zoog

I used to wonder why I was being flashed all the time from behind when accelerating at night on the motorway, then I realised it must be the flameouts after seeing the hedges light up behind me and hearing the "BLAT" simoultaneously on a single track road one night. Guess the guys on the mway thought I was about to blow up or something!Must look superb from a following car. That was in my old heavily modded integrale evo.

Martin J Stirling

Thanks for all the replies guys. Still a bit confused. So what exactly do I have to do to get pops, bangs and flameouts? Also what does overun mean?

Sorry for being so hopelessly thick

Cheers again,

MS

Mellow Yellow !

iTrader: (1)

Hi Martin,
Looks like you've just come back from a good night out......taxi's just dropped me off anyway (there isn't a drunken smiley is there ? )
What exhaust did you go for in the end ?
Are you at Donnington, Brands Hatch ?
Hope you're enjoying your motor as much as I
Spk soon
Chris

Pete Croney

Martin

Over run is when you are still in gear, but are decelerating, so using engine braking.

The throttle is closed, so there is vitually no air to burn any fuel. If the ECU is still putting fuel through the injectors, this petrol mist gets heated to approx 800 degC in the manifold and is extremely explosive (it's flash point is about 37degC). When is comes in contact with air, towards the back of the exhaust, it spontaneously combusts.

A little bit of fuel will give pops and bangs in the pipe, a bit more fuel will give 1 metre rooster tails out of the back

I have also followed a couple of Linked cars, fitted with our exhaust and seen a blue flame glow down the pipe. This is under acceleration and its then followed by a yellow flash on gear changes. Very cool

Martin J Stirling

Pete,

thanks for the explanation mate, I geddit now.


Mellow mi old mate,

yeah - heavy one last night, still managed to type though
I see your getting about a bit in the P1, I haven't dared track day mine yet, I just know I'll get carried away and end up like that P1 at Trax

Sounds like you've got the modding bug big time! Is anything left on your car standard!? I trust you have a VERY understanding dealer

I went for a custom made 2.5" straight through system with the Magnex twin dump downpipe. I'm very chuffed. Just want to get those pops and bangs and I'll be happy.

Take care mate,

MS

T5NYW

iTrader: (4)

Hi,
I've got a MY99 (with ALL cats) and Magnex back box fitted a Atomospheric Dump Vavle and noiced a lot more popping through the exhorst.LOL
Mined you the dump valve nearly p*sses me off as much as the nieghbours
Tony