Hello Guys,

I'm building my next rally car, it is a Mini Cooper S 1600 turbo direct injection with a high comp ratio (10,5/1), 175hp.
The OEM turbocharger is a KKK k03 with small wheels, the max relative pressure is 0,8 bars.

The car will have a 34mm restrictor in the intake of the compressor wheel (the shape of a carburetor Venturi).

The modifications I'll make on the engine : forged pistons and Conrods, completely free exhaust from the turbine, real direct induction, water injection.

What I want : 280-300 hp with as less lag as possible, a lot of torque from low rpm and easy to modulate the torque (for the traction), 98ron.

At this moment I'm hesitating between 3 solutions : Frankenturbo hybrid k03 twin scroll 42mm in billet inducer exh exducer journal bearing, Turbo Lab America modification of the OEM k03 twin scroll 50mm billet inducer exducer journal bearing and Garrett gtx2860r (twin scroll available) 45mm billet inducer exducer ceramic ball bearing (but it is expensive and not direct fit). If you have other or better advice don't hesitate to give me your advices !

The Skoda Fabia R5 rally car use the IHI is38 from the Golf 7R and develop 280hp with 32mm restrictor.

Many thx guys !

 

Hello Guys,

I'm building my next rally car, it is a Mini Cooper S 1600 turbo direct injection with a high comp ratio (10,5/1), 175hp.
The OEM turbocharger is a KKK k03 with small wheels, the max relative pressure is 0,8 bars.

The car will have a 34mm restrictor in the intake of the compressor wheel (the shape of a carburetor Venturi).

The modifications I'll make on the engine : forged pistons and Conrods, completely free exhaust from the turbine, real direct induction, water injection.

What I want : 280-300 hp with as less lag as possible, a lot of torque from low rpm and easy to modulate the torque (for the traction), 98ron.

At this moment I'm hesitating between 3 solutions :

1 Frankenturbo hybrid k03
twin scroll
Compressor wheel 42mm inducer, exducer "size is proprietary", billet wheel 6+6 blades
Turbine 42mm inducer, exducer "size is proprietary" Inconel 10 blades
Journal bearing
995,00 USD
Pros : not too expensive, Etuners obteined great results with this turbo (280hp with more torque than OEM everywhere on the graph), direct fit.
Cons : some says that these are rebranded Chinese Ebay turbos (with images to prove it, at least for the housings)

2 Turbo Lab America hybrid : modification of the OEM k03 specific for this engine
twin scroll
Compressor wheel 50mm inducer, 61mm and 65mm exducer, billet wheel 5+5 blades
Turbine K04 wheel 50mm inducer, 44,40mm exducer, 9 blades
Journal bearing
650,00USD
Pros : Cheap, the guy seems immensely competent, OEM parts modified so it would normally be reliable, direct fit.
Cons : too big for my application ? Will I have turbo lag with it ?

3 Garrett gtx2860r
twin scroll available
Compressor wheel 46mm inducer, 60mm exducer, billet wheel
Turbine wheel 54mm inducer, 47mm exducer
ceramic ball bearing
More expensive and not direct fit
??USD
Pros : ceramic ball bearings, developped by a big brand
Cons : more expensive, will need more parts to adapt it on the car and I don't know if they are availlable.

If you have other or better ideas don't hesitate to give me your advices !

The Skoda Fabia R5 rally car use the IHI is38 from the Golf 7R and develop 280hp with 32mm restrictor Compressor 45,20mm-58,00mm billet, turbine 54,70-47,40

Etuners advice :

"With regards to the setup that you want to install onto your car, I am not sure it is the optimal one you can get just because of the 34mm restrictor required on the turbo's intake.

The GT2860 has a much larger compressor wheel than that.
You will have to suffer the disadvantages of a big turbo without gaining the advantages in power.
Which means that you will have laggy response in corners and slow spoolup because of the size mismatch.

What I would recommend to you is to use cams and a stock turbo, or at most a hybrid with a JCW compressor wheel installed. The car will be in the 220-230hp region even with the restrictor on, with very good spoolup and response. We did a similar project with a couple of Danish Rallye cars a while ago - the restrictor really kills the show in terms of maximum power. "

But the 220-230hp power limit they talk about is not correct because the 34mm restrictor allow a flow of 28lb/min =>280hp limit or about 300 with race fuel.

Many thx guys !

 

Hi Ragnar

I'm trying to achieve the same thing - what did you do in the end and how did you get on?

Thanks

 

To get to the 28 hp limit you need to approach choked flow in the 34 mm restrictor. At choked flow the pressure downstream of the restrictor is about 0.5 atm absolute. Because the compressor has to work with this thinner air, the volume flow rat will be almost double what you normally see for 280 hp and the compressor will have to be sized accordingly. I would plan on a compressor inducer diameter 30 - 40% larger than normal for 280 hp or a flow map that extends at least 80% higher - ie 500 hp at the PR you need. Don't forget the PR will be almost double too. ie to get 2 bar MAP, you are compressing 0.5 bar air up to 2.0 bar - a PR of 4.

The turbine will be smaller. It sees the usual flow for 280 hp and should be sized accordingly.

 

Brilliant thank you - best summary of what's happening / what needs to happen that I've read.