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-   -   divorced wastegate? (http://www.wrxtuners.com/forums/f52/divorced-wastegate-9497/)

drumson5 10-29-2005 04:01 AM

divorced wastegate?
 
Can anyone tell me what the point of having a divorced wastegate or speration of waste gases is for? As everyone knows Perrin makes their downpipe with this. Why would I want to buy a downpipe that can seperate waste gases, vs. a regular large bellmouth with no seperation?

Jag_Warrior 10-29-2005 09:58 AM

[QUOTE=drumson5]Can anyone tell me what the point of having a divorced wastegate or speration of waste gases is for? As everyone knows Perrin makes their downpipe with this. Why would I want to buy a downpipe that can seperate waste gases, vs. a regular large bellmouth with no seperation?[/QUOTE]

Perrin claims the diverter reduces turbulence at the turbo exit, by separating the wastegate gas from the normal exhaust flow. They say it reduces spool up time and increases horsepower. Some other makers take the same approach. Others don't. I don't know who is correct, though Perrin's theory looks good on paper IMO. And their hardware is some of the highest quality and best made pieces I've ever seen. Not cheap but very well made.

drumson5 10-30-2005 01:27 AM

So would there be a big difference in hp gain in the separated one or the regular opening. Would you be able to feel a difference?

Jag_Warrior 10-30-2005 01:10 AM

Feel is too hard to describe, as everyone is different in what they perceive. I've never seen a side-by-side comparison of the two design approaches, so I'm not sure if there is a measurable hp or torque difference or not. I chose the Perrin as much for its reputation and build quality/fit, as for the diverter feature.

Here's a Vivid link that goes into a little more detail.

[URL="http://www.vividracing.com/catalog/product_info.php/products_id/4854"]http://www.vividracing.com/catalog/product_info.php/products_id/4854[/URL]

stileguy 10-30-2005 01:15 AM

get hold of a copy of a book called "maximum boost" by Corky bell, the best money you will ever spend, i felt a difference between a split down pipe mainly in the spool-up area.
apparently exhaust turbulence is highest after the turbine wheel, when the wastegate gasses enter this stream it reduces the amount of gas which can exit both the wastegate and turbine wheel, by keeping them separate for a minimum of 17 inches, it gives the super hot exhaust gasses time to cool thereby compressing and allowing the wastegate gasses to join the main stream of exhaust gas with the least effect on the turbine wheel's speed. it is also advantageous to have the wastegate gas stream join at the shallowest angle possible. in terms of peak power difference i cannot comment on that as i have no access to a dyno to measure the difference after every mod.
get one, it wont be worse than a blended one but it is possible that it will be better, depends on your cash flow. i ended up making full boost 400rpm earlier than a blended one. the bigger the turbo the more noticeable the difference i suspect.
after looking at the pics of the perrin pipe it looks like the separation only goes for 3-4 inches, if the separation is not at least 17inches dont waste your money.

drumson5 10-30-2005 04:05 AM

This is interesting info, Aussie, you might have just changed my plans for just staying with a downpipe with combined wastegate gases and normal exhaust flow. I don't know if you are trying to tell me if the perrin would be a waste of money or not, but I don't really know of someone who makes a product that seperates these gases into two chambers for 17 in. Is this something that is custom made?

smores 10-30-2005 01:16 PM

[QUOTE=drumson5]This is interesting info, Aussie, you might have just changed my plans for just staying with a downpipe with combined wastegate gases and normal exhaust flow. I don't know if you are trying to tell me if the perrin would be a waste of money or not, but I don't really know of someone who makes a product that seperates these gases into two chambers for 17 in. Is this something that is custom made?[/QUOTE]

Bosal makes one: [url]http://www.rallysportdirect.com/shop/product_info.php/cPath/21_25_30_51/products_id/901[/url]

Looks pretty good to me :)

Jag_Warrior 10-30-2005 02:15 PM

[QUOTE=smores]Bosal makes one: [url]http://www.rallysportdirect.com/shop/product_info.php/cPath/21_25_30_51/products_id/901[/url]

Looks pretty good to me :)[/QUOTE]

Well, that definitely looks like 17 inches! :eek:

It would be interesting to see a head to head with a regular dp vs. the Perrin type vs. one like the Bosal. Maybe an old issue of Sport Compact? Anyone aware of such a comparison test??? Is anyone here running the Bosal type that's had either of the other types?

drumson5 10-30-2005 07:40 PM

The Bosal is pretty cool, I think I found one myself also. Its at flatt-racing.com. It has a seperated downpipe, along with these custom headers with the up pipe welded to it already, its all JDM stuff. The dealer is also at fizzautosports.com. Look under JDM products and it will show a whole list of stuff for subaru.

Vew 10-30-2005 08:58 PM

[QUOTE=stileguy]get hold of a copy of a book called "maximum boost" by Corky bell, the best money you will ever spend, i felt a difference between a split down pipe mainly in the spool-up area.
apparently exhaust turbulence is highest after the turbine wheel, when the wastegate gasses enter this stream it reduces the amount of gas which can exit both the wastegate and turbine wheel, by keeping them separate for a minimum of 17 inches, it gives the super hot exhaust gasses time to cool thereby compressing and allowing the wastegate gasses to join the main stream of exhaust gas with the least effect on the turbine wheel's speed. it is also advantageous to have the wastegate gas stream join at the shallowest angle possible. in terms of peak power difference i cannot comment on that as i have no access to a dyno to measure the difference after every mod.
get one, it wont be worse than a blended one but it is possible that it will be better, depends on your cash flow. i ended up making full boost 400rpm earlier than a blended one. the bigger the turbo the more noticeable the difference i suspect.
after looking at the pics of the perrin pipe it looks like the separation only goes for 3-4 inches, if the separation is not at least 17inches dont waste your money.[/QUOTE]

I know Australia seems to have a reputation for modding WRX's seeing they've had it for almost a decade longer than we have. You'll have to keep up updated on the cool stuff we can't get. And maybe help us import a few parts too !Thumbs Up

stileguy 10-31-2005 12:22 AM

Nothin is new with WRXs, the basic platform and engine and gearbox has been done to death 11 years of production and 5 years before that was the legacy rs almost identical to earlier wrxs except for panels and wheelbase. maybe a catalytic converter called MAGIC CAT is one of the more recent things over here (high flow and good for emmissions) you should have it by now, headers are a waste of money on anything less than 500hp+ drag cars, ecus are all quite acceptable when tuned correctly, (Autronic plug and play is the pick of the bunch or MOTEC wire in) gt30-35 are great turbo combinations for big power or IHI turbos which have had the housings modified to take garret cartridges work well up to 450hp (98ron fuel helps too) modified valve bodies and higher rpm torque converters transform autos into drag weapons or for big power fully tricked autos, very few drag with dogboxes these days, autos are half the price and dont bust driveshafts and put down better times. dogboxes are good for autocross and hooligans who wanna tear ass round the streets. not that there is anything with that. with an auto legacy i used to own i did a 1.6sec 60ft with a 13.2@100mph.

smores 10-31-2005 01:36 AM

[QUOTE=stileguy]Nothin is new with WRXs, the basic platform and engine and gearbox has been done to death 11 years of production and 5 years before that was the legacy rs almost identical to earlier wrxs except for panels and wheelbase. maybe a catalytic converter called MAGIC CAT is one of the more recent things over here (high flow and good for emmissions) you should have it by now, headers are a waste of money on anything less than 500hp+ drag cars, ecus are all quite acceptable when tuned correctly, (Autronic plug and play is the pick of the bunch or MOTEC wire in) gt30-35 are great turbo combinations for big power or IHI turbos which have had the housings modified to take garret cartridges work well up to 450hp (98ron fuel helps too) modified valve bodies and higher rpm torque converters transform autos into drag weapons or for big power fully tricked autos, very few drag with dogboxes these days, autos are half the price and dont bust driveshafts and put down better times. dogboxes are good for autocross and hooligans who wanna tear ass round the streets. not that there is anything with that. with an auto legacy i used to own i did a 1.6sec 60ft with a 13.2@100mph.[/QUOTE]

so basically the WRX in Aussie is like the Civic here in the US ROFL ROFL ROFL :tease: :tease: :tease:

;).... I have one still :o

stileguy 10-31-2005 04:56 AM

yes, very few ppl have turbo hondas over here and the few turbo street registered ones are slow as crap, i know more 600hp GTRs than i do 13sec hondas. my mate has an S15 silvia with half the Tomei catalogue which when tuned should make 450-500hp atw on pump gas, another guy has a 1061hp atw Skyline GTS-T which did 9.8@144mph detuned to 600hp atw, my version 6 sti which when tuned is expected to make 230-250kw at all 4, my brother has a lightly tuned RZ Supra (300hp atw) and my other mate with an s14 silvia with bolt ons only making 320hp atw.
Why do ppl in the US put SR20s in 240sx? over here we scrap the SR20s and put 2.5 liter 6 cylinder twin cam engines from R33 skylines into them, gearbox and all with custom tailshaft, brakes etc. just buy an r33 halfcut and you got everything you need, some minor fiddling of engine and gearbox mounts and your away.

Jag_Warrior 10-31-2005 07:45 AM

[QUOTE=stileguy]yes, very few ppl have turbo hondas over here and the few turbo street registered ones are slow as crap, i know more 600hp GTRs than i do 13sec hondas. my mate has an S15 silvia with half the Tomei catalogue which when tuned should make 450-500hp atw on pump gas, another guy has a 1061hp atw Skyline GTS-T which did 9.8@144mph detuned to 600hp atw, my version 6 sti which when tuned is expected to make 230-250kw at all 4, my brother has a lightly tuned RZ Supra (300hp atw) and my other mate with an s14 silvia with bolt ons only making 320hp atw.
Why do ppl in the US put SR20s in 240sx? over here we scrap the SR20s and put 2.5 liter 6 cylinder twin cam engines from R33 skylines into them, gearbox and all with custom tailshaft, brakes etc. just buy an r33 halfcut and you got everything you need, some minor fiddling of engine and gearbox mounts and your away.[/QUOTE]

The cars that get sent over here are like dating what you [B]think[/B] is a hot girl... and then you see pictures of her smokin' hot sisters (that live in Europe and Asia).

Is the Australian STi a (proper) 2.0 liter, and more like the JDM STi, or is it the 2.5 liter USDM type? Do you guys get the STi wagon? Tell us about the pretty sisters that we'll only see pictures of. :rocks:

BTW, are you anywhere near Surfer's Paradise?

Vew 10-31-2005 08:45 PM

I'd like to know about your cosmetic mods, like lips and other stylings what have you. I think you guys seem to have more variety. I could be wrong.


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