Mounting turbo where rear box is, may be good on Cooper

[MINIMANIAUK]

What can be done and what is efficient are two separate things ,you could use the handle end of a hammer instead of the head - how the turbo performs in terms of boost level ,response , and efficiency will be drastically reduced by moving away from the manifold -other than that there are issues with mounting under the car - things like water splashing up onto a hot turbo or snow (we live in a poor climate! ) Running oil lines to the rear of the car,and ducting all the way to the front of the car
The volume of air is not what is used -the manifold design would make little difference, the turbo uses energy from expanding gases that are hot ,at the other end of the car the gasses have cooled and lost energy -low energy in -low energy out
As to the MINI one/cooper any turbo installation will always be expensive and as such unlikely to be done in the near future ,there is no market for it - any development requires that there is someone to buy it and the ONE/COOPER market is very small ( I bet that there are less than 5 cars in the whole of UK with a big valve head for example)

[chuntington101]

Quote: Originally Posted by MINIMANIAUK (original)

What can be done and what is efficient are two separate things ,you could use the handle end of a hammer instead of the head - how the turbo performs in terms of boost level ,response , and efficiency will be drastically reduced by moving away from the manifold -other than that there are issues with mounting under the car - things like water splashing up onto a hot turbo or snow (we live in a poor climate! ) Running oil lines to the rear of the car,and ducting all the way to the front of the car
The volume of air is not what is used -the manifold design would make little difference, the turbo uses energy from expanding gases that are hot ,at the other end of the car the gasses have cooled and lost energy -low energy in -low energy out
As to the MINI one/cooper any turbo installation will always be expensive and as such unlikely to be done in the near future ,there is no market for it - any development requires that there is someone to buy it and the ONE/COOPER market is very small ( I bet that there are less than 5 cars in the whole of UK with a big valve head for example)

some very good points there. esp the stuff on the market. but surley being able to fit the kit at home would make ti much more appealing than having to pay one hell of a lot of money for a converison.

oil lines running to the rear are not a problem. just think of them as brake lines. you could even make hardline kits! what about the return? well its been done soo many times, on both front and rear mounted turbos, that the best solution is a electric pump the simply pumps the oil back to either the head (not the best idea but the sinmplist) or to the sump (requiers a little more work). you can build in sensors to alert the driver if there is a pump failure.

you are right about putting the turbo closer to the exhaust ports but that means you need a manifold to mount the trubo onto. these have to be custom as no one sells them. you cant get cast manifolds as they would be terriably exspencive to make. so you ahve to go with a tubular one. now i love the look of these manifolds and you can do some neat things with them (twin scroll/divided housings can work really well). there are down sides, such as cost to make and craking! you dont get any of those problems with a rear mount! well you are using most of the stock exhaust.

if you are really worried about damaging a turbo by splashing it with water (and as you said the turbo will be running cooler anway) then a simple ally shield could be fabbed to redcue it. same gose for the air filter.

finally the manifold. first the volume has a massive effect on how the turbo system responds! reduce the header size and you WILL get faster spool simply cos the exhaust gas speeds will have increased (more kenetic energy). so if you fit a manifold with say 2inch heards it will cause the turbo to lag. you are correct about the gasses cooling but there are things you can do that have been proven to help with this. using heat wrap or even coating the exhaust will all help keep the heat inside the exhaust gas and help spool. as with every turbo applictaion specing of the turbo is VERY important and even more so when the turbo isn't running as efficently. from what other have done it appears the best way to spec the trubo is to sellect the correct turbo for the power you want, then sellect the next smaller exhaust housing to what a front mount would run. this should compensate for the reduced temp/energy in the exhaust gasses.

as i have said before these things have been done many many times. STS for one is aiming their products at the guy that wants to get his hands dirty but hasn't got a F1 crew to help enginer the kit to work. its proving very sucsessfull for them. ok its not as effective as a front mount but you have to see the benifits of these systems to.

Cheers

Chris.

[chuntington101]

MINIMANIAUK, just like to say thanks for resoponding to my posts. i think these exchangers are really good and are what make the forum. the fact that an idiot like me can try and put his point across to engineers like you guys is great!

thanks again

Chris.

PS. this isn't just aimed at MINIMANIAUK but all the other guys and girls on here that openly shear the knowlage they have, be it a little or a lot. this really is a nice and relaxed forum with little argueing or p!ss taking.

[MINIMANIAUK]

No problem , the rear mounted turbo will always be slow spooling compared with the front one ,there is one advantage the short distance to the exhaust tip in that the back pressure is minimised .
I cant see that there are any real cost savings and this would lend itself more to the cooper s as a twin charge system -the lag would be less of an issue

[Silent1]

Quote: Originally Posted by MINIMANIAUK (original)

No problem , the rear mounted turbo will always be slow spooling compared with the front one ,there is one advantage the short distance to the exhaust tip in that the back pressure is minimised .
I cant see that there are any real cost savings and this would lend itself more to the cooper s as a twin charge system -the lag would be less of an issue

Yes but providing you keep a small diameter pipe the velocity of the gas will be high so in theory apart from the negligable compression of the gas due to restriction, it won't be that bad.

[MINIMANIAUK]

You have to look at the whole picture - velocity ,temp and pressure are linked - across the turbine there is a temp drop and pressure drop - the greater the difference (drop) the better the result (thats why turbos like low back pressure in the exhaust as the drop across the turbine is better .
Turbines are designed around TIT (DONT LAUGH) turbine inlet temp the higher the better ,but too high and you get melt down - (hence EGT guages the EGT is in fact the TIT )
part of the design is also the velocity -this dictates the angles used in the turbine blades , the turbine is made to suit the application ,using a turbo designed for use near the cylinder head with high temps and velocities would in the first instance be wrong further down the exhaust pipe .
price wise the installation would be roughly the same for either -the turbo price the same ,more stainless ducting on the rear kit and an extra oil scavenge pump,longer oil lines , against the cost of an exhaust manifold. In a ONE /COOPER ther would still be an ecu to be fitted and boost pressure sensor and injectors and lower comp piston and......