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Author Topic: A short question  (Read 1856 times)

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Offline TimoXr4i

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A short question
« on: August 09, 2012, 22:06:59 PM »
Not for me, but for my brother in law.

He has a oval racer with a cossie 4 pod lump, but, like a cossie the engine broke down, and got rebuilded by a sponsor, and has some extras to get it on boost early, about 320 horses, no problems with that, but, there is a bit of a problem, the car has a short exhaust, only a single damper and the exhaust is about 100 cm from turbo till endpiece. After the rebuild the engine runs fine, the boost is up early, but, it has flames from the exhaust, and about all the time, while the other setup only spitted flames when coming off boost. The flames are not a big problem for us, but the track owners dont like it much, becouse the tracks are mostly grassy and pretty dry, so, they say its risky, is there anything wrong, why does the damn thing it, and could i do anything about it?



Offline capri v8 driver

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Re: A short question
« Reply #1 on: August 10, 2012, 07:59:15 AM »
Basicly the flames come out when your car does give the engine to much fuel and it cant burn all in the engine and when it comes out of the exhauste the "cold" air makes it's density to grow and it ignites from the heat of your engine exhaust.

A short exhaust isn't helpfull to avoid flames either.

1 way to deal with it is to reprogram the ecu to avoid dumping fuel into the exhaust when you close the trottle (overrun) the other is make the exhaust longer, so the gasses in the exhaust have more time to cool down, before they leave the exhaust.
greetz Paul.

Capri V8 Driver.

Offline TimoXr4i

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Re: A short question
« Reply #2 on: August 10, 2012, 21:55:40 PM »
Hi paul, m brother in law tried a different map, cant do much about the exhaust, but while he says the flames are only there with overrun as you call it, witch is okay to us, the t25 seems to burn oil, so, he has something to do over the weekend :mellow:

Offline TwinTurbo

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Re: A short question
« Reply #3 on: August 11, 2012, 22:32:33 PM »
If the turbo is burning oil then you may need to up the back pressure in the exhaust ( somethig a 100cm exhuats will not have.).

Also, the map for the eninge may be fair, a bit of post cylinder ignition is not always a bad thing.

It all comes back to the very very very dark art of induction and extraction.

Why have you gone with such a radicaly short exhaust? has it been proven to be better than a full system?

TT


Offline TimoXr4i

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Re: A short question
« Reply #4 on: August 11, 2012, 22:58:18 PM »
Hi tt,

The turbo never smoked before as much as it does now, it always had sme blue smoke, but now its there a lot more, so probs something with the turbo.

The why on the short exhaust? Its a tubular frame, engine, roof, firewall and driven axle need to be of the same brand, everything else is free, but, normal fuel, and no 4x4, so, its a short wheelbased car, rearwheel drive, and it doesnt have much plate as floor, only under the chair. Its pretty low, and tou really dont want a red hot glowing 2,5 inch steel tube anywhere near you, so it goes to the side, just behind the frontwheel and comes out of the side. Most cars dont have a tubo, but are atmo tuned 250 hp engines and frontwheeldrive, like audis, vw, opel/vauxhall, and few hondas, but, we have one of the few rearwheel driven cars, together with some volvos, and they all have short exhausts, exept from some very well balanced audi 1.8 20vt engines, but they are quite a lot faster, and dont brake down a much as the escos t25 engine. After the season there will probs come a duratec or something like that.

The frame started as a mercedes e190 frame with a 2.5 mercedes cosworth, but is a ford for 4 years, gearbox is a short ratio sequential 4 speed box, but, becouse of the old technique in a fairly heavy lump, its by far not the fastest car in the field, always subtop, after the stupid fwd audis without the turbogap :unsure:

 

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