Glen McCartney

DR, can you give me a call to talk about the new manifold setup? You should have my cell number
Thanks
Glen

AO

Thanks Brad. I figured it should be something simple like that. I might take DR up on his offer for the updated style. Not sure yet. Since I just bought the Twin-Screw Euro, play funds are a bit tight, but I always have a secret reserve for bail and other emergencies!

DR, wow! That's a pic from the past! 666, really? I must be 235+ in that pic. You wouldn't recognize me today being a svelt 185.

BTW, I'm really happy to see you back and engaged these days. It's just not that same when you're "MIA".

Vlocity

Hey DR & AO,

That new manifold sure looks awesome, I still am running my "early Andy" manifold and getting ready to pull it as I am down on boost. That's after 7 plus years (I can't remember either) of steady track work.

When I get the system taken down and diagnose the problem I may give you a call and see what I could convert. Some extra HP sure would be nice.

Ken

AO

Hi Ken-
Good to hear from you. The seals on these SCers can go bad if pushed too hard. The insides of mine were coated with oil. I think part of the problem is the self-contained oiling. While convenient, I don't think it has the longevity that we'd like. I'm seriously considering running an oil-filter sandwich to divert some oil to the SCer and then drain back to the sump. The nice thing is I think I can add that at a later point should I want to.

Anyway, good to hear from you.

Tony

If the seals are bad wouldnt you tend to see oil on the outside of the gear case/snout? When under boost Im sure SC casing and gear case become pressurized and would show up on the "outside"?

Isnt this the purpose of the set screw in the snout where you can place a hose leading to a "catch can"..so you can relieve any pressure?

AO

I thought so too, but in my case when I opened it up, there was oil everywhere. I haven't pulled the SCer apart yet to see what seal is bad or how it failed. Still debating on whether I should bother to or not.

I bet I was ingesting S/C oil for quite some time. It rarely came out of the snout and yet I was "filling" it up every 500-1000 miles. Luckily it wasn't a huge volume, but still probably reduced power.

I have to pull the snout off no matter, so maybe I'll see what's going on there. I'll post what I find.

Vlocity

I've never lost or added any oil from the SuperCharger, just changed it once a year.

I would like to send mine off and have it rebuilt if needed. I'll know more in a month when I have the time to tear it down. I expect to find a leak somewhere. I was down to 4.5 pounds. My old supercharger probably won't fit one of DR's pretty manifolds.

AO - Good to hear from you as well. I've been too busy to be on the boards of late, but hoping to be a regular once again.

Ken

DaveUK

Hi, I have a couple of questions about what you guys do to the motor when running boost (i'm sure the answers are here somewhere but this is a loooong thread!):
Are you running stock compression ratio & if not how do you lower it?
Are you running stock cams / timing & if not what are you running?
How do you map the ignition timing, specifically what defines the limit of advance you will set?
What engine mods are needed for what levels of torque?
What 'while you're at it' work should be done during a conversion?

I plan to go down the twin-screw route and my plan so far is like this:
get a twin-screw blower on there with potential for decent poke, but run really low boost & stock ECU while I get the intercooling and air intake mods well sorted out
fit uprated fuelling system & probably new ECU, up the boost a bit and map
love the torque, want more, get bigger pulley & re-map!

AO

Welcome! Most of us are running completely stock internals. Stock pistons, rods, cams, etc. The 928 motor is very robust - trans too. Stock components seem to be pretty bullet proof up to about 500 HP at the wheels. Beyond that, things start to break.

I've been running about 8-10psi (actually found my boost leak last night) for some time and everything has held up pretty well. Make about 440 RWHP. As you may have seen, I recent pulled the SCer for fittment of a slightly larger unit that should put me at around 500RWHP.

The 87+ cars can continue to use the stock ECUs with some tuning. Some of the 84+ cars can too. You should talk to John Speake who is one of your countrymen as he makes the unit to re-tune the stock ECUs.

The twin-screw is a great supercharger and is best suited for automatics, but I've been successful with it on my 5-speed. If you have a 5-speed you may want to upgrade your clutch as the torque curve on the twin-screws is pretty aggressive.

Feel free to ask any more questions you might have.

AO

Last night, I did a test-fit of the new, larger, supercharger. I was concerned that the airbox might not fit given the extra length of the SCer. I will have to relocate the ISV, but that shouldn't be a big deal.

I've decided to give the stock head gaskets a try. My son and I are going to go shopping tonight to find adequate spacers a la Bill Ball. I think I should be in a position to re-fit the SCer this weekend and button things up. This project wasn't nearly as big a deal as I was dreading. I should have done it a long time ago.

Here are a couple of pics showing the clearance of the airbox. Not the best angle, but I'd say I still have about 1cm between the airbox and the AC lines. It's gonna be a tight fit getting some of the hose clamps on, but it should be manageable.

EMan 928

Looking Sin-ister, Andrew!

John Speake

Hi Dave,
As Andrew says, you don't need to change the stock fuel and ignition ECUs when you supercharge.

The SharkTuner was developed specifically for that purpose.You can fit larger injectors, retain the stock fuel system. It has been used up to power levels of well over 700HP at the flywheel.

See http://www.jdsporsche.com/Mk%202%20sharktuner.html

The cylinder heads of the 32v 928 engine are perfect for supercharging, their design is based on that used by the 956/962 race cars.

OBehave

Andrew,
With the larger blower and expectations of 500hp and up, won't you need to upgrade to a SuperMaf?

AO

Nope!

There are two ways to get around the super MAF. Murf uses a restrictor donut to reduce the cross-section of air the MAF measures.

In my case, since I have twin throttle boddies, the MAF sits in front of one and measures the air on only that one. The other throttle body is unmetered. So I'm only measuring 1/2 of the air. Then through the Sharktuner, I compensate either by fuel load or injector size - or a little of both.

Imo000

So this system runs under the assumtion that both intake paths flow exactly the same amount of air?