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Home > Help Needed / General Tech Chat > Suck through turbo 998 advice


2 Posts
Member #: 11793
Junior Member


Hi, Im in the middle of building a suck through 998 with a gt1752, ive had the car running and driving at 10psi boost, it drives ok but is burning oil badly because of the vaccum in compressor housing sucking oil past seals, now Ive searched around and cant find a carbon seal for the gt17 so ive decided to run a throttle set up in between turbo and inlet to stop vaccum in compressor housing, but im struggling for ideas on how to do it, ive got a rover k series throttle body i was going to use but would like to see some pictures of other peoples set ups and some advice on the job really



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9234 Posts
Member #: 123
Post Whore

Betwix Harrogate and York

I'm not really sure what you're trying to do. I sounds like you want to build a blow-through but using the setup you have?

It would be easier to build a proper blow-through setup than bodge what you have I reckon.

I don't see what you have can't work though. Are you sure the oil is coming through the seal because of the vacuum? as in, does the oil clear when you get boost?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.

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10906 Posts
Member #: 17

SouthPark, Colorado

I agree with Will, by the time you’ve gone and added a butterfly, why not just do it properly and make it a blow through.

I think the only way you’re going to get a poppet valve to work is to add a restrictor after the compressor, but before the valve. So now you’ve compromised the improvements.
Yeah, I just go ahead and do it properly, adding an intercooler at the same time!

On 17th Nov, 2014 Tom Fenton said:
Sorry to say My Herpes are no better

Who remembers this first time around:


81 Posts
Member #: 11403
Advanced Member

Any videos of it running, looks loud with that exhaust lol

Turbo technics made a suck through kit, i have a complete new kit in a box that i bought ages ago, looks sort of similar to your setup


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4821 Posts
Member #: 1775
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That picture looks exciting

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Rod S

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5846 Posts
Member #: 2024
Formally Retired

Rural Suffolk

The "suck through" turbos of days gone by did use carbon compressor seals as you obviously know from your original post.

The standard piston ring type seal will certainly let oil in under vacuum hence why they made the carbon type for your configuration.

From the garrett parts catalogue it seems the carbon alternative is only available on the "T" series turbos, not the "GT" series.

Which leaves you little choice, change to an older, less efficient turbo with a carbon seal option, or mess around with an additional throttle plate after the compressor which will probably cause all sorts of problems with the mixture because of the way an SU works.

Schrödinger's cat - so which one am I ???


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6456 Posts
Member #: 828
Post Whore


yes , back in the 80's ? i advised on a install on a freinds car , he put a 2nd butterfly in , it worked well .you simply get a throttle cable with a split and two cables coming out of the other side of the split(like on a twin cylinder bike) ,, one goes to the carb, the other to the throttle body , try to have the carb one open a bit more than the throttle body one , so its the body that is controlling the engine , in fact , you may be able to do without the one on the carb all together .



Edited by robert on 12th Sep, 2018.

Bicester scramble ,Medusa enjoyed the trip.

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