OK so I'm a bit over the inefficiency of the sc12 supercharger, and want to go turbo. I have got a T25 and can get a turbo manifold for ~$200 from the US, but inlet manifolds are a bit more tricky. It's currently suck through, and I think it would be pretty easy to put the throttle body in front of the turbo and use the standard manifold.
Intercooling wont be a problem because it wont have petrol through it, but what I want to know is do turbo's leak oil because of the petrol, or the vacuum when the throttle is closed? ie. will I need carbon seals even though theres no petrol going through the turbo?

You can see there's plenty of room on the exhaust side, and if I use a supra/soarer intercooler with the outlets on the same side piping shouldnt be too bad.

sounds like it's a blow through setup your proposing....

in which case you dont need carbon seals

your basically using a t25 in the same setup as it was originally fitted on the CA18 anyway

nah, notice how the throttle body is in front of the supercharger, not on the inlet manifold. I'm thinking of mounting the throttle body in front of the turbo, so air goes through the TB, then through the turbo, cooler, manifold..

but being infront of the supercharger it is not measuring compressed air anyway so it could be place almost any where along the inlet tract? but fomthe photos looks like it it is feeding from a frontmount of some kind so it could be anywhere between intercooler outlet and turbo inlet. Probably mounted there for ease of instalation and mounting.

Bear in mind though that it probably on the front of the supercharger so that the lag is minimal as its almost measuring the air as its needed. Angles and distance to the impeller will have to be similar from the turbo to the supercharger as not to effect air flow in any negative way.


Is it on lpg?

No LPG. I'm not sure how it will affect lag, but throttle response will be pretty bad, there is a lot of air between the throttle body and the engine.
I'm not sure what you mean about measuring the air? Are you referring to a AFM? if so thats not an issue as it is MAP sensored.

if you put the throttlebody infront of the turbo it will create a big vacum across the turbo and suck the oil out, you can reduce this vac by having a second throttle body close to the inlet manifold that works at the same time as the other one but this is used for a carb suck-tho system.

By the looks of yours you are running the 4agze computer etc... so just relocate the throttle body to next to the inlet manifold and run like normal, (just check your air/fuel ratio once its up and running)

ok cool so its the vacuum that sucks the oil out. I was thinking maybe the seals get eaten away by the petrol.
Its running an Autronic SMC.
I'm not sure how i would put the throttle body closer to the inlet manifold, I've seen the 2nd TB stup used on a supercharged 4agze and it looks like a real PITA to set up.

On a blown motor, you gotta run drawthrough. Otherwise the piping between the supercharger and the TB will blow off on overrun. (When the engine is decelerating with the throttle body closed) Due to the pump pumping air, and it having no-where to go. I know a bloke with a supercharged CA18 who runs blowthrough. But, he runs a blowoff valve. However when it's on overrun, All the air being pumped by the blower (1.4 litres per revolution) exit through the BOV. This makes a VERY loud buzzing sound.
By and large, A turbo stops pumping when you lift the right foot, so blowthrough is far better suited. I would just convert your set up to blowthrough and be done with it. By the time you shag around and add a second TB on the turbo outlet, you might as well just go blowthrough and be done with it.

Just my 2c

yeah you're probably right, I'm just a cheap-arse trying to avoid paying for a inlet manifold.

Hey tyrie, why don't you simply make an adaptor for the throttlebody to bolt straight onto the inlet manifold. If you buy a piece of aluminium of about 25mm thick, you could easily make your own adaptor in your garage, with drill, file and some elbow grease. I originally would have done that, and infact I finished the adaptor plate, but ended up changing the inlet manifold.

That's also not so difficult, you simply get someone with a large cut of machine to cut the original manifold of, about 40-50mm from the face. You then buy a piece of aluminium tube of 101mm dia and 4mm wall thickness. Also some 4mm flat alu which you'll use to close the one end, and other gaps that might appear, and a round pice slightly larger than the pipe, of about 15mm thickness for the throttle body flange. You cut file and fashion everything so that you have a finished manifold, you simply stick everything together with some masking tape to do fitting. Afterwards you take it to someone that does alu welding, and have the lot welded together. The holes for the runners into the plenum I did afterwards, as they then have more metal to weld onto, and you have the liberty to do some shaping afterwards. That is exactly what I did down to the last little piece, and it wasn't to much work, you should be able to see what I mean from my pictures I posted...

I'll see if that adaptor is still around here, and I'll take a pick and post it. This is the easiest and most cost effetive way for a start, and anyone can do it. You'll just need a 90 bend from the top of the throttle towards your IC.

EDIT: Found it, didn't quite seem to finish it, but you'll get the idea...