SilverSFR

James,

1982 16V 928s single BAE/Rayjay T04 non-intercooled turbo 64K miles 5-speed.
the Turbo was installed by a company in Southern Cal called BAE systems @1986. the PO stated that it cost 16K. The car had 9000 miles on the clock when installed so it looks like i got 20 years and @ 55000 miles before she let go. Majestic turbo informed me that it was time and lack of proper cool down that killed the turbo not the miles. the good news is that parts were still available for the repair of the turbo. so it should be a plug and play reinstalation.

1175.00 turbo rebuild
250.00 tail wastegate
100.00 jet coating
100.00 new silicone hoses and t-clamps
35.00 SS dump tube
75.00 new SS bolts and misc hardware

pretty inexpensive compared to having a new turbo system retrofitted.

SilverSFR

Fabio421

"This turbo stuff is the future, man. As soon as someone cooks up a twin turbo kit for an S4 I'ma buyer.

The S/C I have is cool but IMHO a turbo is a ultimate goal.

Can you fill us in on the specs for the system? Single turbo? IC?"


Explain why you prefer the turbo. I was always under the impression that a SC was more desireable performance wise because you had the power immediatly. The turbo is going to have lag and produce most of its power at higher RPM. I thought the SC would help to remedy the lack of low end oompf that these Porsche engines seem to suffer from. Am I off base?

SilverSFR

fabio,
That is a trick question with an answer that boiles down to personal preference. Blonds or brunetts would be an easer question to answer. with so few turbo 928's around this forum, my answer would be the minority and one that could get me killed. I prefer the turbo setup because thats the way it came. Boost is boost.... long live the boostards.

SilverSFR

Herr-Kuhn

Depends on the SC you are using...positive displacement will have instant boost off idle, centrifugal can not and won't ever match boost curve of a positive displacement. The turbo is best because it allows you an efficient setup when cruising and the most boost with the least parasitic drag on the engine as compared to any super charger system. It goes like this:

Positive displacement...lots of boost down low with high power to drive the super up at the top end..good for off the line and mid range
Centrifugal...peak boost at redline only, at 1/2 redline you have about the square root of the peak boost number and still have some parasitic draw off the crank...though it is a lot less than positvie type...can make a lot up top but not much mid range or down low
Turbo...Setup properly you can have full boost by 3500 RPM with low parasitic draw on the engine...make a lot of mid range and top end.

The turbo is the chioce for endurance cars and the like and is Porsche's choice too. It is the best forced induction technology going.

SFR...nice setup...that manifold looks really close to my design. You need to charge cool that car....I can get you hooked up on how to do hot wire and charge cooling if you want.

SilverSFR

John,
good to hear from you. I want as much info as you can spit out. I think we all would. For the near future i just want to get her back on the road.

SilverSFR

Mark

Are you using a boost controller. like an APEXi?

Adam C

My car currently has an Eaton M112 SC running 7.7 pounds, intercooled, and supposedly getting 400RWHP. I will know after a dyno.

I would like a twin turbo because I like the elegance of the solution compared to the SC. I like the fact that it isn't belt driven, and I have fought with belt tension issues. And there is at least a glass ceiling with SC power on the 928. I'm happy with the SC but IMHO a twin turbo setup is the king.

With twin turbos 800HP on a purpose built 928 is doable.



Quote" Explain why you prefer the turbo. I was always under the impression that a SC was more desireable performance wise because you had the power immediatly. The turbo is going to have lag and produce most of its power at higher RPM. I thought the SC would help to remedy the lack of low end oompf that these Porsche engines seem to suffer from. Am I off base?"

Ketchmi

Uhhh 800hp is also do-able with a centrifical system.........

BC

Its my impression that with an 18psi ratio for CS at 6500rpm, that there would be considerable boost at 3000rpm.

Fogey1

CadCam! While those manifold pieces are off is the perfect time to get them scanned and digitized so all the bends and such can be reproduced again. Or am I way off about what can be done?

Talk about a community service.

Who's around to help? Bueller, Gates, one of you guys that works for HugeCo, Inc.?

G Man

That turbo setup doesn't look like it would be too hard to replicate. Does your car have any sort of special fuel management system or is the stock AFM able to handle it? I'm still considering the rear mount setup. Not all the way in the back but where my cat is supposed to be.

SilverSFR

Gman,
Mostly stock execpt for a vortec FMU. Fuel pressure looks good and the ARM1 says my ratio is where it needs to be. a little on the rich side. It was if Porsche built the 928 fuel systems to flow a little more than they needed to. stock injectors and stock FPRs..

SilverSFR

cobalt

Very cool,

I agree nothing like the woosh sound made by an open WG. Now I am assuming by what i see you are not useing an IC? Is it possible to incorporate one into the design?

I am curious to know when you achieve full boost though. My turbo starts building boost a little earlier and is at 1.0 bar by 3200 rpms. I am assuming at .5 bar you should be at full boost by about 2500rpms which should be rather tame. Although the K27 HF is a rather large turbo and takes time to spool up. I prefer the added power myself between 3000 and redline. I like twisty roads and having the power up high is were I use it most. Unless 0-60 is important to you the power is best in the higher rpms.

I don't know much about your turbo but Kevin on the 993TT 996TT and 964 Turbo boards along with Stephen from Imagine auto have come up with some great hybrids. They may be able to help you in your quest for more performance.

Cool down is very critical for turbos. You can easily shorten their life by shutting down without allowing them to cool down. Heat will cause coking of the bearings and once this happens it is a short road from there.

Did you ever think of an electronic boost controller with a larger spring? You can use a larger spring and reduce the pressure to suit your needs. It will not allow you to go beyond the max setting of the spring but will allow you to cut boost down for those bad weather days or long trips to save on fuel economy.

Good Luck and keep us informed.

heinrich

Cobalt, remember your and other turbo cars have lower cr .....

cobalt

Yes i do realize. We are only running 7.5 to 1 and the 993TT's are at 8 to 1. Although you could probably squeek a .6 bar spring in there and keep it set at .4 or .5 bar with an occasional bump up to .55 bar for added punch if needed. Risky maybe but there if you dare. It is really more there to turn down the boost for when it is not needed. on long trips or rain. Besides, I thought some of these SC's were running 7.7 or more PSI which is more than .5 bar without any gasket issues?

I run at 1.0 bar which is high but the turbo engine could probably handle an occasional bump up to 1.1 or a very short 1.2 bar run without shortening engine life. As long as the AFR is OK. If you could add an IC that would be a big help.