Pop
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Registered: 8th May 03
Location: Reading
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ok i'm prepared for a slagging but i have some possibly stupid questions about turbos...
it's something i'm looking into and knowing not very much i'm trying to learn more. it will be for a system running about 7-8psi so nothing major
1. i know you're looking at an exhaust system with a 2.5-3" bore. does the cat make a big difference? would it still be preferable to go with a sports cat still?
2. do all turbo systems still have an air filter as part of the system?
all help is much appreciated
thanks
tim
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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yes, yes.
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Pop
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Registered: 8th May 03
Location: Reading
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well that was fairly harmless... i'll go away and think of more things to ask. thanks
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Sam
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Registered: 24th Dec 99
Location: West Midlands
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I have a question - how do you make a turbo so hot it glows? 

[Edited on 29-07-2006 by Sam]
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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Run it for a long time. My mates turbo mini engine bay used to glow red after a longish journey, didnt need the heaters either as the box it sat in was right near his leg
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Pop
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Registered: 8th May 03
Location: Reading
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ok if you are turboing a petrol car which doesn't have a turbo as standard, will it have an external wastegate?
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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the wastegate is either built into the turbo, or seperate..... so either, depending on what turbo you use
oh, you cant use a diesel turbo on a petrol engine, the turbine blades wont like it.
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Pop
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Registered: 8th May 03
Location: Reading
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thanks again...
not wanting to offend anyone who has one here... are screamer pipes only associated with really big power cars?
[Edited on 29-07-2006 by Pop]
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Jake
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Registered: 24th Jan 05
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Ferarri F40 has one i think as does muppetsport. So its purely a max power thing
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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apparently, going on what i've been told by Mr Sport, the screamer pipe is just the pipe which lets charge air out of the wastegate. you can either have it going back into the exhaust system, or venting to the outside
you technically need one if you run an external wastegate... its just a matter of how loud you want it to be
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Pop
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Registered: 8th May 03
Location: Reading
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i understood it as when you reach full boost then your external wastegate feeds the air down a separate pipe (screamer pipe) so that it doesn't all need to channel through the full exhaust system
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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quote: Originally posted by robmarriott
apparently, going on what i've been told by Mr Sport, the screamer pipe is just the pipe which lets charge air out of the wastegate. you can either have it going back into the exhaust system, or venting to the outside
you technically need one if you run an external wastegate... its just a matter of how loud you want it to be
Nope, lets exhaust gases out, the charge air is what goes into the engine
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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yeah, the wastegate opens and releases the excess pressure, to stop the turbo overboosting
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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good spot ash.
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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quote: Originally posted by Pop
i understood it as when you reach full boost then your external wastegate feeds the air down a separate pipe (screamer pipe) so that it doesn't all need to channel through the full exhaust system
Yeah, but in most cases, the wastegate is integrated into the turbo: a little hatch opens and the exhaust gases bypass the turbine, stopping the turbo from boosting too much.
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Pop
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Registered: 8th May 03
Location: Reading
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ok then.. i'm stumped here.
what is the difference between a wastegate and a dump valve?
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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Dump valve opens to release excess air being pumped INTO the engine. Basically the throttle will shut, and to keep the turbo spinning, a dump valve opens to release the pressure until the throttle opens again to let the charge air into the engine.
Wastegate operates on the other side, allows exhaust gases (which power the turbo) to bypass the turbine and stop the turbo spinning too quickly, which can cause too much heat buildup, damage to the turbo etc.
Try here for an explanation of turbo basics mate:
http://auto.howstuffworks.com/turbo.htm
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Pop
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Registered: 8th May 03
Location: Reading
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thanks.. will take a look at that site the now
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CorsAsh
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Location: Munich
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Pop
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Registered: 8th May 03
Location: Reading
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still looking at that site and making sure i understand it all...
one thing though... even on a low pressure system are the risks of engine failure greatly increased with mileage on the engine before turboing?
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CorsAsh
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Registered: 19th Apr 02
Location: Munich
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Well yeah, if you have an engine which has been designed to run high compression for natural aspiration and you whack on forced induction, it's gonna end up with a compression ratio that the engine was never designed to handle. So unless you address that, expect big problems.
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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your compression ratio is 10.8:1
it WILL need lowering, either with dished pistons, or a spacer on the block
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Pop
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Registered: 8th May 03
Location: Reading
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yep part of the work would be lowering the compression ratio... oh the joys, but it would be entertaining in my car
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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what sort of power would you be looking at though? would it not work out better just to put a GTI180 engine in?
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Pop
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Registered: 8th May 03
Location: Reading
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all sorts of issues with a gti 180 engine...
my car is non-multiplexed wiring, but all gti-180's are multiplexed. they also run a fly by wire throttle.
a tb, full exhaust and cams setup is looking at 190-200bhp
not 100% yet on the turbo. i need to speak to carworx first to see what i could do within my budget. if i can't afford it then i'll walk away, at the moment i'm happy with what i have
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