Strange turbo position.

[bob1179]

I was watching the Discovery channel last night and there was a programme on called 'Rides'. In this programme Chevrolet had a new people carrier thingy (HFF? HSS?)and they decided to give four of them to four different tuning companies to be used as show cars.

Anyway, one of the cars had a turbo fitted to it, but instead of sticking it just after the exhaust manifold under the bonnet, they placed it right down the exhaust next to the rear wheels. The guy fitting it said it ran cooler here and he didn't have to interefere with the emissions equipment on the car.

I've never seen a turbo being fitted this way, they didn't use an intercooler, there was a load of pipe work required and the turbo was open to the elements. Is there any benefit to fitting it this way (other than it seemed a very simple way of fittig a turbo)?
I was always told that when fitting a turbo keep it as close to the inlet and exhaust as possible to reduce lag, I take it this set up would cause a lot of turbo lag and would the turbo even spin as fast being so far from the engine?

I'm just curious and thought I would ask the great PH collective for their opinions.

[chuntington101]

this has proen to be a very effective way of mounting a turbo(s) on big engined cars. i have seen them on a whole host of V8s from the US, viper engined trucks (not a viper its self though!) and even on a new M5!!!!

they are never going to be as efficent as a front mount turbo setup but there are some advatages. also if you could untilise a VNT turbo or make a sequnetial style system you could have a very effective, yet disreat and easy to work on turbo system!

take a look on www.ls1tech.com and www.corvetteforum.com for some info on how the GM guys over the pond do it. also have a look on here www.ststurbo.com for kit this company make.

thanks CHris.

[bob1179]

Cheers Chris.

There is some interesting stuff there.

Do you reckon it would be a good way of turbo charging a 3.5 litre M30 BMW engine?

Edited by bob1179 on Monday 30th April 13:02

[GreenV8S]

I'd expect it to be very laggy and relatively ineffective, but maybe still 'good enough' if you aren't expecting much from it.

[stevieturbo]

GreenV8S said:

I'd expect it to be very laggy and relatively ineffective, but maybe still 'good enough' if you aren't expecting much from it.

This topic has been covered a few times on this forum...

It might surprise you at how "good enough" these setups actually are.

There are some 7 second cars using it....

Admittedly lag isnt a concern from those cars, but there are plenty of very fast cars that arent laggy using a rear mount...or a twin rear mount.

[chuntington101]

bob1179 said:

Cheers Chris.

There is some interesting stuff there.

Do you reckon it would be a good way of turbo charging a 3.5 litre M30 BMW engine?

Edited by bob1179 on Monday 30th April 13:02

Well I would always try and get the turbo up front if you could. But if it prove too hard to fit the turbo, or is causing problems, in the engine bay then this is a viable option. You will have to look at the turbo a little more closely and maybe talk to a turbo expert with rear mount experience.

Have a look what other people are doing and see what works and dosen't.

Hope this helps?

Thanks Chris.

[chuntington101]

GreenV8S said:

I'd expect it to be very laggy and relatively ineffective, but maybe still 'good enough' if you aren't expecting much from it.

well you dont get much lag when you have a 5.7ltr+ engine and a well matched turbo. and there is always Anti-lag!!

Chris.

[spend]

OT, but is it possible to move cats to the back or would this prevent them getting hot enough to work?

Dave

[chuntington101]

spend said:

OT, but is it possible to move cats to the back or would this prevent them getting hot enough to work?

Dave

most guys take the cats off. if you want to keep them its not a problem (not heard of anyone destroying a turbo thanks to a nice piece of cat) but you will see higher back presures.

thanks Chris.

[GreenV8S]

stevieturbo said:

GreenV8S said:

I'd expect it to be very laggy and relatively ineffective, but maybe still 'good enough' if you aren't expecting much from it.

This topic has been covered a few times on this forum...

It might surprise you at how "good enough" these setups actually are.

There are some 7 second cars using it....

Admittedly lag isnt a concern from those cars, but there are plenty of very fast cars that arent laggy using a rear mount...or a twin rear mount.

I thought the conventional wisdom for turbos was to try to carry exhaust pulses straight into the turbo so you benefit from the peaks of the pressure waves. Letting the gas speeds average out and cooling the gas down (presumably reducing volume and hence speed and kinetic energy) seems like a backwards step. Having much more volume is inevitably going to make lag worse rather than better.

No doubt anything can be made to work, but surely it'd be likely to work better with the turbo in a more conventional position close to the engine?

[stevieturbo]

And same as was said in previous threads...

Yes, we all know it isnt ideal, ots the most efficient system.

But its cheap, and it is effective.

And when some states in the US are strangled with CARB and emissions laws....

Bolting a turbo AFTER all the emissions related equipment, means its much easier to get CARB approval for these stringent states.

Do some research on it. It may sound silly, but there are plenty of rear mount cars out there, faster than most cars in the UK with a front mount turbo. So you can laugh, but they might have the last laugh if it was a head to head race.

[chuntington101]

Green, all what you have said is true! but when you look at some of the systems for mounting the turbo(s) up front you could see why some go the rear mount route.

as for volume is really not that relavent. if you run equal length tubular headers you will be getting i bet your not going to be a million miles off what these guys are getting for the volume of the manifolds, Y-pipes and turbo pipe. most of the singles are running a single 3inch pipe back to the turbo.

you mentioned head, and the importance of keeping it in the exhaust gasses. the STS style systems do by design make it harder to achive this. but there are solutions. using stock manifolds dramatically improves the amount of heat ratained as does coating or wrapping the hot pipes.

heres a car worth looking at. www.ls1tech.com/forums/showthread.php?t=706568

Chris.

[bob1179]

chuntington101 said:

bob1179 said:

Cheers Chris.

There is some interesting stuff there.

Do you reckon it would be a good way of turbo charging a 3.5 litre M30 BMW engine?

Edited by bob1179 on Monday 30th April 13:02

Well I would always try and get the turbo up front if you could. But if it prove too hard to fit the turbo, or is causing problems, in the engine bay then this is a viable option. You will have to look at the turbo a little more closely and maybe talk to a turbo expert with rear mount experience.

Have a look what other people are doing and see what works and dosen't.

Hope this helps?

Thanks Chris.

Thanks again mate, I'm just looking at my options and costs at the moment to see what is viable. I'll drop an email to some specialists and see what they have to say.

Bob