Mikes3.0cabturbo

HI, this is my first post so hope this is the right way to do this...

I have a 90 Cabriolet 3.0 944, the reason for posting here is there seems to be more experience in tubocharging the 3.0 than other areas.

I am nearly finished a low boost tubo conversion using mostly a stock 944S2 3.0, it has a 2mm cometic headgasket with static comp around 9.8:1, MAF, 4 extra 22lb injectors (in addition to stock injectors) in a custom manifold, SMT6 with a MAP controlling boost timing & extra injectors, 3" downpipe & exhaust. I have used 944 turbocrossover, intercooler, mount etc. Boost will be a maximum of 9-10psi, but everyday on about 7-8psi. 95 otane pump gas.

What is the best turbo considering my street only requirements, and low boost. I expect around 340-370 flywheel hp depending on boost. No plans to go any more. Broad street torque wanted.

I have been told TO4B 60-1 HiFi KKK#8 stage 5 turbine - or TO4E50 KKK#8 stage 5.


thanks
mike

TurboCab

Mike:
I have a 968 Cabrio Turbo. The first turbocharger that I installed was a 60-1BB with KKK#8 turbine housing and stage V trim. The turbo lag was minimum with great throttle response. If I remember correctly, boost start to build around 2K RPM's. It will work very well with your projected boost pressure. However, this turbine will not work for high boost, let say 13+ psi. It is simply too small for a 3.0L high boost application. I "fooled" myself thinking I'll be happy with a low boost application, and ended wanting more HP. I have to change the turbo for a one with a bigger trim and AR. If you are very sure that you will not change your mind in the future, go with the StageV #8. Hope this help. Just my experience.

Mikes3.0cabturbo

thanks TurboCab, I can relate to your commentrs about the wanting more, for the time being I think I can be happy with the lower boost and your reply based on experience was exactly what I was looking for.
Just for interest when you later upgraded did you change both compressor and hotside, if so are you opeb to share what?
thanks
mike

TurboCab

Mike:
I went all the way to the Garrett GT35R (Ball bearing). This turbo have similar compressor and turbine trim to the 60-1, but the new Gt series wheel design allows for better air and exhaust flow. The turbine AR is .82 which is bigger than the KKK #8 (#8 = .6X) The bad thing about the Gt series is that it is a completely different turbo than the T Series. All the exhaust plumbing was modified along with others things to make the turbo fit. The GT35R and 60-1 full size (4" inlet) have similar air flow specs, can go to +/- 600 Hp. My 60-1 turbo was a Kokeln Stage V unit. I think the unit comes with a KKK turbine housing. Since the turbo used the HI-Fi compressor housing (2.75" inlet), it fits like a glove. I think that you can use a similar compressor trim than the 60-1 which have enough HP potential in case you changed mind. In this case you can buy a bigger AR turbine and you’re done.

Mikes3.0cabturbo

really helpful TurboCab thanks - I will order my 60-1 this week.

TurboCab

Mike:
Couple of important things:

1. Turbine housing must be a KKK #8 or higher. Do not use a smaller AR.
2. Turbine Trim must be Stage V (2.437" inducer diam. and 2.795 exducer diam.) Do not use a smaller trim.
3. If you can, buy a ball bearing unit. Better spool up and surge resistance.
4. If you buy a Ball Bearing unit, an oil restrictor must be used. (less than .050")
5. There are other knowledgeable people in this forum, you may want to hear other experiences and recommendations.

Mikes3.0cabturbo

the folks I was planning to buy from were Innovative Turbo, they can provide #8 or a #10 hotside to go with the stage V trim, I was worried about going to a #10 causing slower spool. I really wanted a street car that had early spool - less than 3000rpm for 7psi or thereabouts, I very rarely take it beyond 6k rpm.
Is your suggestion to go to the #10/stageV?
thanks

RajDatta

I think a #8 would be good for your low boost low power setup. If you want more top end, you can go with a #10. A friend is curently running a K27/11 on his 16 valve but we used it because at the time he felt that he wanted to use 1bar. Since then he has accepted .8bar as the level he can run with factory electronics so we plan to move to a #8 to lower spoolup times.
Raj

TurboCab

Mike:
As long as you keep your boost level around 7-10 psi, you can use the #8 housing.

Mikes3.0cabturbo

I've read a number of folks are running K27-7200, the compressor maps between that and the 60-1hifi are quite different, do they perform similar in real world terms?

Seems that the consensus is to stay KKK#8 stage V, thats a decision made.

RajDatta

Yeah, I was talking about the 7200 series. that turbo is only oil cooled.
Raj