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stup 05-09-2008 09:51 AM

Worthwhile turbo upgrade from 965 3.3 standard k27-7200
Over on rennlist there is a post about basically which turbo is the most worthwhile to invest in with a slightly modified 964 turbo 3.3,e.g a car fitted with say headers/cams,1 bar boost,around 350-400 bhp at wheels..
I know the turbo may be different to suit peoples needs however i was looking for examples??..The HFS keeps getting suggested however it seems to gain a little up top but at the expense of slightly slower spool unless i am wrong and somebody can show me data to prove..i personally would have thought there would be a turbo on the market that has been developed and would replace my standard 17 year old designed turbo and give me gains in all areas??..
My standard k27 7200 works not to bad however does not maintain enough flow after 5.5k+ to keep me at 1 bar boost to red line,i do believe the HFS will hold 1 bar to the red line but it has been said at expense of some quick spool time down low which if true it seems not that worthwhile to me then.
Is garret the only way to go and are they reliable??

jeff91C2T 05-09-2008 12:25 PM

Hey Stu,

Ya, I'm following those threads too. Wait...I think I might be somewhat responsible for them ;-)

I think the HFS has improvement on the low side but it's called a more "linear power delivery", or something like that ;-)

stup 05-09-2008 01:06 PM

Yeah something like that Jeff!.ha! you are probably i am a bit disapointed with the results in finding a turbo to better my k27 7200,until somebody can come in with results on a good upgrade,it seems maybe the above mentioned turbo aint so bad??

RarlyL8 05-09-2008 05:33 PM

My $0.02
The 7200 runs out of breath on the dyno but I cannot tell myself until the top of high gear.
If you wish to stay with the T3/KKK flange then you have a couple of choices. The K27S is good if you have stock heads, the HFS is good if you have ported heads and a modified fuel head.
I do believe there are other non-KKK turbos that may be superior choices at reduced prices.

965addict 05-25-2008 08:08 AM

Can't say my HFS is a BIG improvement over the standard K27. It certainly does have more at the top end but possibly slower spool at the lower range. I have an airfield test day coming up in June, so will post findings afterwards.
With the standard headers and turbo, I noticed I lost power near red line (which is why I installed the HFS) but still managed official 168mph vmax. (My car has been measured with mixtures both before and after so is running fine.) If I can't better that with headers and HFS I'd say that will be conclusive. We'll see...

JFairman 05-25-2008 08:45 AM

I went from a perfectly good K27 7006 to a new K27 HFS.
My car has B&B headers, Garretson half bay intercooler, Imagine Auto fuel head, Brain Leask adjustable control pressure regulator, and Powerhaus group b cams.
Someday I'll get around to installing a set of SC330 cams and rebuilt rockers I have sitting around.

Spool up speed of both turbos seems about the same on my car but may not if you have stock or SC cams, I have no experience with an HFS other than my own car.

There is a huge increase in boost up near redline with the HFS. It doesn't run out of breath at high rpms in 2nd or 3rd gear at all in my experience and the 7006 does.

You can speed up turbo spool up time with very careful adjustment and use of one of these boost valves, but you can hurt the motor real fast if you don't start with very conservative spring pressure and dial up the spring pressure slowly between test runs.

I installed one yesterday with the 1/4" fittings mounted in the engine compartment and it works great.

There are many other boost valves out there to choose from made from anodized aluminum of all shapes and colors that cost a little more.
For $39 plus shipping I felt this one was worth a try and I definately like the results.

I'm sure lots of guy's wouldn't want to risk one of these but if you have a bigger better intercooler, start slow and don't go over 1bar with it using street gas and some type of fuel enrichment, it will make a noticable increase in spool up speed, power, and acceleration.

930gt-40r 05-25-2008 11:05 AM

Stup- you need a Garret GT-35R dual ball bearing. The only thing that sux is that you have to modify the flange on the muffler side to fit the turbo. But you can get one for somewhere in the $1,200 range and it will spool very nicely while still pulling nice up top. And then sell your K-27 7200 to one of your fellow Pelicanites with an earlier car that needs one...

stup 05-25-2008 11:55 AM

What other mods did you do to get your garret to work with reliability,e.g oil feed etc

930gt-40r 05-25-2008 07:57 PM

Stup I sent you a PM.

turboteener 05-26-2008 07:44 AM

You might look at the new Bullseye turbos from Borg Warner. Apparently they are making more power than the equivalent Garretts. There have been significant advancements in turbo design in the last 20 years. Spool up time really won't change unless you change something on the exhaust side. Ball bearings are the way to fly when running a big single.

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