Twin Turbo 325i, one rear mount, one up front?

[Chuntington101]

This idea of only using one of the two exhaust inlets to the turbo seems great. Some people are simply blanking off one of the inlets, some are setting up a pressure sensitive gate to the second inlet once the boost has been reached in the first inlet.

Anyone know how the gated one is setup?

oil issues on rear mount turbos are normally dealt with by placing a electric pump dwon stream of the turbo. you use the engines oil preusre to feed the oil to the turbo and then the pump to pump the oil back to the sump. some guys have tried mech pumps (like dry sump pumps) and they work but are more expensive than these eletric ones.

327ire, the gated turbo setup that you posted work very simply. its a T6 turbo fitted to a V8 (around 350 cubic inch or 5.7ltr). it would normally be conciidered a BIG turbo for a V8 of that size.

however as only half the trubo is being fed at low rpm the turbo spools pretty quick. however the now very small AR would choke the turbo at higher RPM. so the wastegate opens once full boost is reached and allows the trubo to breath.

With your car i would try a much bigger turbo than the turbo you currently have. i recon you could use the same size turbo as the front mount guys and have similar lag to them.

327ire you pics are not displaying for me. If you PM me i can send you my email address and you can send them to me.

Cheers

Chris.

[Turbo-Brown]

Aah, supplying oil to the outlet of the turbo will not lubricate the bearings very well at all!

The bearings aren't an oil bath type affair where sploshing about in oil will keep them happy, they're hydrodynamic bearings which rely on a supply of oil to the working surfaces which actively keeps the surfaces out of contact.

[327ire]

Im using a CT26 from a 2l toyota engine. Its a fairly large sized turbo I think. Its used as a twin turbo setup in a supra also. Its sort of perfect for my app. Its input and output both face the same way (u-turn), and it has a bracket on the top so iv had very very little moding to get it piped and mounted.

baptie0 thanks for the input!! The turbo is only clearing the ground by a few inches so i dont think i could run a sump below, maybe parallel?

[Chuntington101]

Aah, supplying oil to the outlet of the turbo will not lubricate the bearings very well at all!

The bearings aren't an oil bath type affair where sploshing about in oil will keep them happy, they're hydrodynamic bearings which rely on a supply of oil to the working surfaces which actively keeps the surfaces out of contact.

to stop the turbo oil beraring siting in a pool of oil i think most gusy use small 'pills' to restrict flow into the turbo. as for the return you want it as big as you can!

Chris.

[Chuntington101]

327ire im not firmilier with the CT26. have you got any more into on it like inducer size and tuerbine AR??

it wuld be intresting to try this twinscroll idea and see how it performed!

Chris.

[e30_Turbo]

i recon you could use the same size turbo as the front mount guys and have similar lag to them.

Whats lag?

If you know how these things work you should know we all have anti-lag built in, called a gearbox

I'll happily take anyone on for a 60 to 1?? pull in 5th, I get awesome response even tho I use a 67mm turbine in a 18cm3 housing. I get boost from 2.5k too, full chat @ 3.6k.

Chuck a holset on there! Most are twin scroll but I think you can do this much easier than that.

Mark

[327ire]

CT26 specs,..

the stock CT-26 turbine housing has an A/R of 0.49 and a 56-trim compressor wheel.

but this guy says,..

turbo runs a turbine a/r of .63 and use 45 trim wheels

From what ive been told they are the same as the ct26 that came out on the 7gmte supras but use a twin scroll so it can spool up on the smaller 2.0l 4pot motor

[baptie0]

which ever way you feed the turbo, the oil has to be collected below.
you can either pump the oil back to the engines sump or pump oil back into the turbo,
if you choose to pump oil back to turbo, you need a separate resovoir before the pump.

to make your system work you need 2 pumps, 1 to feed turbo from oil tank and 1 to return to tank. could the turbo be mounted in the boot?.

hope this makes sense.

[327ire]

Thanks it does. Looks like the best system involves 2 pumps.

[327ire]

I think Il try....
sending the oil from the engine to the turbo,
and pumping it back to the engine using the same 12v pump that i had before.

Il check the pressure when it reaches the turbo at the back.



What would you lot recommend as piping / hose? Im thinking a small diameter towards the turbo so I dont loose too much pressure, 6mm maybe?

The return through the pump could be larger. I think a 8 or 10mm hose was perfect before. This section would be running under the car so there is some opportunity to cool the oil before it enters the sump. Any ideas?

[327ire]

and also,.... whats the best point to tap into the engines oil to send to the turbo? m20 motor

[baptie0]

take the oil from the oil pressure sender, you can buy a t piece to do this, demon tweeks sell them, and aeroquip hose to feed the turbo. i used 6an hose to feed my turbo.

[327ire]

So Iv bought another turbo and pump. Im not sure where the input and output for the oil is located, can you lot help? Thanks in advance!!

The seller supplied a diagram but i dont think it makes sense...
The ct26 is water cooled.

[joecrotch]

hello there! just came by for a visit from e30tech.com wanted to see how things were going across the pond.


.....i do a lot of turbo builds. and am very familiar with the ct26 the actual version your using is not a very efficient turbo for you the turbo starts to sputter out and fall on its face at around 12 psi. 6-8 psi is the best range for this turbo. also what are your goals just brute power,response,reliability? because if you haven't rebuilt this turbo yourself chances are its about 19 years old ans from a reliability standpoint that's not gonna last u long. i would suggest replacing the seals at least on it. i have done 4 builds with the ct26 out of mk3 supra s which is the better ct26. i dont know how hard that is to find in the uk but here they are all over junk yards i have 4 sitting in my garage freshly rebuilt. but just know this is a extremely small turbo for your car. i would be going to yards looking at old volvo turbos with the t3 flange! anyway if you have any questions feel free to ask i have a lot of knowledge when it comes to the ct26

[joecrotch]

just saw you last post.......the water cooling ports can be ignored on the ct26 just make a little plate to cover them so no dirt or grime gets in. and remember if your gonna run a standalone oil pump u need to use a restrictor on the oile feed i run a plate with a 1/16 inch hole in it which keeps the oil pressure down to 5 psi (still a little high). but the ct26 or any turbo needs little to no psi just to be bathed in oil any pressure in the system is the pressure being forced on the seals and the seals are not made to hold oil under pressure. well good luck

i did a rear mount turbo on a Pontiac firebird and we ran the oil from the pressure sending unit to the turbo then from the turbo to a trunk (boot) mounted sump u could use the overflow tank u were using then using that pump you have pump from the sump to the engine oil pan. that car was buil 4 years ago and the owner is still driving around on it today.

[327ire]

Thanks your a massive help!!!

So b1 is oil in,... b2 is oil return? (see pic above)

Im going to feed the turbo from the engine. Any idea how much pressure I will get from this? So on the oil input on the turbo will need to be decreased in size to a 1/16 inch hole rather than the one thats already there?