Rear mounted turbos

[ausgolfer]

Ok of all my silly cannot afford performance improvement aspirations this one probably takes the cake, but lately have been discussing with work colleages a bit about rear mounted turbos.

The idea goes that you take your car, albeit already "modified for boost" and put a turbo where the rear muffler should be. Then run a boost/intake pipe back up to the engine.

Benefits:
*apparently (big claim and I'm sceptical) not bad turbo lag as the inlet and exhaust lengths are so similar.
*no need for an intercooler because of the loss of heat through the exhaust hence not heating up the turbo and not transfering as much heat, also the long inlet/boost pipe back to the engine being exposed to the "cooler" atmosphere cools the inlet charge aswell.
*you can still use your extractors increasing efficiency.
*apparently they sound like something out fo this world, in a cool way.
*one less muffler as the turbo quietens up your exhaust.
*cost, cheaper and easier to fit.

Drawbacks:
*not sure about the turbo lag as mentioned above.
*because of the long distance between the engine and the turbo, you have big heat losses and hence the exhaust gas will occupie less volume hence not giving you as much momentum to drive your turbo?? not sure about this either just an assumption.
*just read on a link I'll put up that they are less efficient because of the exhaust energy loss between the engine and the turbo.

Here are some pictures of this set up on a porsche 928.
http://www.vwwatercooled.com.au/forums/images/imported/2006/11/p928rt1-1.jpg
http://www.vwwatercooled.com.au/forums/images/imported/2006/11/p928rt11-1.jpg
http://www.vwwatercooled.com.au/forums/images/imported/2006/11/p928rt12-1.jpg
http://www.vwwatercooled.com.au/forums/images/imported/2006/11/p928rt13-1.jpg

[ausgolfer]

http://www.vwwatercooled.com.au/forums/images/imported/2006/11/p928rt14-1.jpg

Yes as you can see I'm very busy on a friday night....

Here's the link to some video's of a C6 corvette with twin rear mounted turbos, sounds rather NICE and goes rather WELL.

http://www.streetfire.net/2006/08/rear-mount-turbo-on-corvette-c6.aspx

[ausgolfer]

What do you guys think about putting one on a golf?

[joshyd-mk2gti]

Benefits:
*apparently (big claim and I'm sceptical) not bad turbo lag as the inlet and exhaust lengths are so similar.

Drawbacks:
*not sure about the turbo lag as mentioned above.


it seems like a pretty big bit of pipe to pressurize, i think it would be pretty laggy. but i dont have any experience with this sort of thing, so i could be wrong. still, would be a cool project.

[golf3]

One thing for sure, you'd have to clean the intake filter a lot if it sits near the ground, and don't drive in the rain!

[ausgolfer]

I don't think that'd be a problem sean, you could easily make up a few covers for your airfilter.

[peedman]

You'd need really long oil lines for one. Sorta practical for V-engines if u want single turbo but really, who would bother.

[Oneofthegreats]

IMO I wouldn't bother. There's enough room in any golf engine bay to fit a turbo in.

Depending on what type of turbo you run, you'd also need a very long coolant lines too which are exposed to a very abusive environment. You'd also need a pump of some sort(Holley Blue) to scavage the oil from the turbo & pump it back to the engine which will also be exposed.

I've seen this setup on some car's & I won't deny it doesn't work, it would fine, but I would question the overall efficency of the setup.

Any engine can be turbo charged regardless. Depending on how much flow, boost & especially cyl. pressure's(that's the important one) you require depends on how you must build the engine within reason as some of today's engines don't need any modification's at all.

For eg. the current gen4 LS4 has a static CR of approx 10+:1 & you can fit GT42R to them on pump fuel & with the right setup & tuning can easily make 400+RWKW!

Stock standard 20VT's with a CR of 9.5:1 can make 500+hp with the right setup.

10 year's ago it was unheard of that any turbo'd engine had anymore than 8.5:1 CR(except for diesel's;) ), but with ever increasing engine component quality, turbo's & engine management technology this has changed the way people think about forced induction of any kind.

[Bug_racer]

Stock standard 20VT's with a CR of 9.5:1 can make 500+hp with the right setup.




I have to disagree here , 400hp is the most you can get out of the 1.8t before you should be upgrading the rod bolts . You probably could get 500hp but not reliably . After 450 hp though you'll need to run a gt30 and you'll have to lower compression ratio due to static compression being too high for the turbo size . You will also have a problem with the piston rings and gt-30's .

Apart from that everything else is correct , its a waste of time .

[Oneofthegreats]

I have to disagree here , 400hp is the most you can get out of the 1.8t before you should be upgrading the rod bolts . You probably could get 500hp but not reliably . After 450 hp though you'll need to run a gt30 and you'll have to lower compression ratio due to static compression being too high for the turbo size . You will also have a problem with the piston rings and gt-30's .

Apart from that everything else is correct , its a waste of time .

Yeh I just realised. I should have said the BAM/TT225 engine's CR 9:1. They can & have done 500+ even with the AEB's & AGU's but your right, after 400 with a larger frame turbo's the rod's can't really withstand the cyl. pressure's & start to bend. I've never heard of any problem's with the BAM piston's nor anything about the standard ring's.
I've seen them modify(open up) the top & second ring gap's but only if there running after market piston's eg. JE, wiseco etc.

[Bug_racer]

They are using thin rings on BAM pistons which over time start leaking . I have seen some actually crack and snap . Definately need thicker rings for more boost .

[SOHC]

I have thought of that but never thought somebody actually did it...
bloody engineering terms:mad:

[hiho]

you could have a seperate oiling and cooling system for the turbo, i cant see how the lag would be anything other than rudiculous though