What turbo and headers?
 

I'm thinking of upgrading the headers and turbo on my 83 euro 930. The engine has sc cams, Andial one bar spring and intercooler. The tranny has an lsd and a lower geared (than stock) r&p.

As it is now, it has way too much lag for my taste. Can I mostly elimate lag on this engine by swapping out the stock euro exhaust and stock k27? If so, what parts would get the job done?

Thanks-
Craig Backer

I think going to an aftermarket headers alone will net you some useful gain, both spool up time & power.

What would be the best turbo to reduce lag. I'm not interested in large top end numbers.

Many things contribute to lag.
As you know, the turbo you choose must match the application and work optimally with the other components. To minimize lag in a stock engine with SC cams you might consider the following:
- K27/7200 or HF range turbo that can operate from 2500-6000rpm
- Short run headers
- Cam timing on the retard side
- Finely tuned A/F ratio throughout the operating rpm range.

Headers and cam timing will give you the most return on reduced lag. The choice of turbo needs to follow your chosen operating range, such as 2500-6000rpm. There may be more optimal units than the K27 series, I am not familiar with them all. Finely tuning your A/F ratio will give you 20+ HP, reduced lag, sharper throttle response, and better fuel mileage all at the same time.

Rarlyl8 hit it right on the head.

Along with the useful info that Rarlyl8 has already said. Keep in mind The hot side size (number, for a kkk) will determine lag or lack of it. When dealing with a kkk that hot side number should be no bigger than an 11 for the street.

I've used both the K27-7200 and K27-HF and now I run a Garrett GT35R ball bearing turbo and have never been happier with the performance on the street, with aftermarket headers also :cool:

Wydryd,
When you changed to the Garret turbo, did you notice a substantial improvement over the K27-Hiflo?
If so, what other modifications did you need to make to have it fit?
For example, any mods to the intake side connections to the intercooler?
Any mods to the exhaust header or is it direct bolt up to the flange?
Any mods to the oil supply plumbing to the turbo? What about the oil return tank plumbing?
I am interested in going down this path over a KKK unless the Garret is too much modifying to make it fit and work correctly.
Bear in mind that I will be running CIS with this setup.

Thanks in advance for info,
Fred

Fred, I had the very first K27-HF with the 2 3/4" inlet on the compressor. It was a nice little improvement over the K27-7200 I originally used on my car and had better top end.

When I decided to go with the Garrett GT35R, I also replaced the OEM heat exchangers with a nice set of aftermarket stainless steel headers, so the vast improvement over the old setup would have been a attributed to a combination of the headers + ball bearing turbo.

The Garrett GT unit will bolt right up to the headers, however, you will have to modify the inlet flange to your muffler and also run a smaller oil feed line (-4AN) since the Garrett doesn't need as much oiling as the KKK units.

The GT turbo also has a different oil drain flange pattern, so you'd need to have your oil drip tank modifed with a GT drain flange on it.

If you're tracking your car, I'd recommend running oil through the water passages on the GT turbo. For pure street, they are safe to run oil cooled only. Just leave the water ports open.

Whether you decide on a K27HF or GT BB unit, it'd be a vast improvement over the factory 3LDZ turbo/paper-weight :cool:

Mate the new turbo with a nice free flowing muffler, and you're good to go ;)

had to share my header/turbo set up as of this morning


http://forums.pelicanparts.com/911-engine-rebuilding-forum/323599-my-3-2-ss-twin-plug-turbo-motor.html

Hey Merv,

How does the GT-35R compares with the K27HF?
I'm curious if it is "bigger" than the HF or its simply builds boost faster.

hobieboy, as I said earlier, when I went with the GT35R, I also did a full header upgrade and the difference was night and day. The 35R flows more than the HF and also spools much quicker. I was getting close to 4K rpm spool-up with the HF, but the 35R puts me right at 3-3.1K :cool:

Thanks Merv.... I knew you did both headers & GT35R at the same time. Good to confirm that the GT35R flows more than the HF though - with EFI, maybe I should consider that too :)

Re: spool up time, just curious how much what that is turbo vs headers...

whoa full spool at 4 k? Wow I guess I did not realize that is where those cars came in to it own.. I was shooting for 2600 and got about 2900-3100 with mine but again low boost

I get 3K at 1.0bar of boost :eek: Once the 35R starts spooling and your foot is planted, the boost builds aggressively and shoves you back hard! I can feel the rear 285's struggle for traction ;)

Mind you, I'm still running a crap generic tune in my Motronics. I can't wait to go with a standalone EMS & twin plugs :eek:

I'm not knocking the other newer KKK stuff out there. I'm just talking from personal experience with my setup and I'm very happy with the choices I've made SmileWavy

Hobieboy, the HF will spool up quicker than the 4K that Merv has mentioned with his factory exhangers in place. Most owners have gotten full boost at 2800-3000 RPM.. The GT35R does not flow more air. The performance indicator is directly related to your exhaust system and fueling CIS..

Zeroclearance, the HF I had was the original with the 2 3/4" inlet. I was told by the supplier it would flow 550HP... the GT35R is rated as a 600HP turbo... it does flow more air than the original HF I had. The newer HF's have a bigger compressor cover I believe?

Merv, your supplier might have told you that.. However, since I MAKE the Hyflow series, the Hyflow has a 60.5mm compressor wheel the GT35 has a 60.85mm compressor wheel. The compressor wheel in the Hyflow is more efficient.

Your engine has been reconfigured, you would have been surprised at the numbers that the Hyflow would have rung out with the new changes to your engine package.

So, for my stock euro 930 engine with sc cams - Am I right in thinking that I should run a set of short run headers and either the kkk27hf or the Garrett GT35?

The hf requires much less modification, correct?


Thanks for all the input. Good reading-
Craig Backer

Has there been any 3rd party testing to verify this? It seems most of the 'seat of the pants' dynos don't agree with this statement.

I am not sure of where zeroclearance is getting his GT spec. The GT35R that I am looking at has 68mm compressor wheel. It is my understanding that the GT30R has the 60mm comp. wheel.