Ahhh... very very sound concept! ;) I like Carrera/Pauter/JE part the best. Very non-porsche-snobbish and very very good stuff-

Few hints (please don't take it as criticism):

1. I would ditch 1 bar wastegate spring. Autronic has built-in electronic boost controller and all you need is solenoid to contol boost line going to wastegate. It can only raise the boost from level provided by spring, so you would need 0.7 bar spring in order to allow Autronic to regulate boost from 0.7 and upwards.

2. How do those BB-headers look like? You seem to be handy and expirienced in DIY, so you could even try fabricating your own headers? As you probably know, turbocharged cars don't care for equal length headers. They just want it hot and short (at least before the turbo).

3. Spinning more on your DIY-handiness: there is lot to be saved on using some other (cheaper) sort of EFI. SDS will do both fuel, ignition and boost controlling for half the cost. Tuners don't speak it as fluently as Autronic, but you could learn a new language yourself ;)

4. Ever tought about trying Garrett GT-series turbochargers? ;)

That engine will rip any way you do it!

Cheers!

David, I live in Willis. Not to far up north of Conroe. We should hook up some time. I'll be glad to help you with your rebuild some weekend! I have an 87 930 that's down right now too. I will be doing the same things to mine so maybe we can help each other! I am also enterested in the Kart racing and wouild like to find out more about it. Looks like your doing a great job!

Hi David,

I see your using ARP head studs. I think you may have them the wrong way round in the case (I did the same thing). The rounded end with less threads is for the head nuts, the other (with max threads) goes into the case.

Cheers

Paul, please tell me you're kidding! I didn't see any directions on it and it seemed like bottoming the rounded end in the case would help even out the upward pull. If they are backward, what problems would this cause?

EDIT: I called EBS and asked about the studs (why didn't I do this before?) I did in fact install them backwards :mad: They said I should have used red loctite with the bullet end out (I used oil). They said since I have full thread contact on the nut, but no extra threads, I shouldn't have any problems. Let's hope I don't blow it up or have major leaks and get a chance to correct them.

beepbeep,

1) I've thought about putting a lower pressure spring in and use the Autronic controller and still may do it. I haven't completely decided on how the ECU will be set up. I'd like to have it so I don't have as much boost in 1st gear when I'm traction limited but I don't know how I'd send a gear position signal to the ECU.

2) I've also thought about building some custom headers using Burnsstainless tubing and their awsome collectors, but this project is way over budget right now.

3) My other thought on ECU is Motec so I've already lowered the cost quite a lot by going with Autronic.

4) My plan on this rebuild was to build the bottom end to handle future upgrades such as a monster intercooler, custom exhaust, and better turbo. Since these are all items I can add without opening the engine, I'm saving them for the next step.

Great work! When can I drop my heads off for this mod? :D

Hi David,

I hoped you hadn't got any further in your rebuild when I spotted the head studs. I made the same mistake and mine were locitited in. Fortunately it hadn't completely set so I was able to remove them and re-install them correctly. I'am using an EMS Stinger CPU to control my engine. It is controlling the fuel, ignition and boost. The EMS Stinger is quite a bit cheaper than an Autronic (both are made here in Australia). The Stinger retails here for $995(that's Australian dollars). It's controlling the ignition via a M & W Pro 10 Ignition unit (again made here in Australia). My system was setup by PEM here in Australia.

Cheers

What's this guy still doing in my garage??

Paul, thanks for letting me know about my head stud installation mistake. After thinking about if for a day, I went ahead and pulled the engine apart and changed them. Now I'll be able to sleep better.

FYI on Loctite: A Loctite rep came to our shop and gave a presentation on how to use Loctite. One tip he gave which relates to 911's is on the head studs. He said when you're using Loctite on a blind hole, put the Loctite in the hole and not on the stud. He demonstrated why with a clear plexiglass blind hole. If you put the Loctite on the stud, when you thread it into the hole the air in the hole doesn't allow the Loctite to go into the hole.

Nice machining and build up! I highly doubt I'll have the balls to toss my heads on the bridgeport when I do my next build...

Nice tip on the loctite! Got to file that one for future reference.

Would be great to have a "1001 engine rebuilding tips" book:)

Great you made the right choice David. I know I had one sleepless night worry about those head studs. I had put the loctite on the threads, but it was the wick in variety, and some of those studs were quite hard to remove.

Cheers

Grady/Anyone,

Let's see your pictures of this plug connector under the valve cover set-up...

Thanks
Scott

It looks to me like you'd need to cut out the fins on the second plug hole to use the under valve cover plugs. I would like all the fins I can get so I'll be using plugs that go throught the valve cover.

Not sure if this is what you are looking for, but this is a pic of the lower valve cover on my twin plug project.

Don, are you using 12mm plugs on the bottom? If so, are the plug wires specific to the 12mm? What do you think about the quality of the Clewett wires?

I have no idea on plug size - I use Bosch FR5DTC. All the Clewett stuff I bought has been top shelf stuff. And everything has bolted right, unlike most everything else I bought.

David, what sort of power output are you expecting from your engine when its complete?

Andy

I'm figuring about 500 to 550 fwhp.

As posted by Scott Walthuis---------------
Grady/Anyone,

Let's see your pictures of this plug connector under the valve cover set-up...

Thanks
Scott.---------
And me!
Bob

David,

Do you recall what the head angles were on the mill? Also, how much did you shift the head to keep the hole closer to the exhaust valve side of the head like the original? I'll end up coming to my own conclusions here but it would be nice to bump my findings against yours...

Here's another thought on the small plug and smaller 1.0" dia second plug hole. Since my plug ends measures .92 dia. the rubber boot will nearly be touching the heads fins when installed. The question that comes to mind here is will the close proximity of these parts deteriorate the rubber too quickly... Is this plug boot available in silicone???

Thanks
Scott

Scott, I don't remember the exact angle but I do remember adjusting it a bit as I did the first head. I believe the port was 32mm and the largest bore size in the port was 36mm. I wanted the port to be about 41mm, so I set the angle for a taper a little less than from 41mm to 36mm at the required depth. I bored it to the depth of the 36mm bore then moved the mill head up about .040", milled again, raised the mill head milled again, etc. until I was at the 41mm port size. So I ended up with several little steps that I blended with a sanding drum.

I don't remember why I didn't just bore it straight from 41 to 36mm, but I must have had a reason at the time.:)

Dave,

Sorry if I wasn't clear, but my questions were concerning the second spark plug hole.
I do plan to open my ports as well so thanks for that FYI.

Thanks
Scott

I didn't write down any of the angles.

Dave,
I'm curious about the thread depth for the second spark plug. Many twin plug machining results in no or very slight relief cut in the combustion chamber. Yours seem to have quite a bit. Did you cut to match the length of the plug threads? Also, did you cc the heads and check the comp ratio after the work?

I set the plug depth on the 12mm the same as the 14mm. I cc'd the heads and a piston after the work was done so I don't know how much I lost. If you assume the relief is 1cc, then it's about a 0.08 point loss on my engine's compression. After cc'ing the heads I decided to use JE pistons to raise my compression from 7.2 to 7.7.

Plug depth
 

I managed to start on mine over the holidays, one side is done anyway...

Concerning plug depth, in my case it turned out that buy the time the sealing surface cleaned up I was already deeper than the original plugs. No problem though.
I replicated the original angles indexed the head 180 and moved 4 tenths (.4"). I went with the 14mm plug and will likley use the "F" (FR5DTC) series Bosch plug which has a 5/8" hex, that's what's in the pictures anyway. I hope they come in handy...

Scott

http://forums.pelicanparts.com/uploa...1104897691.jpg http://forums.pelicanparts.com/uploa...1104897732.jpg http://forums.pelicanparts.com/uploa...1104897748.jpg http://forums.pelicanparts.com/uploa...1104897765.jpg http://forums.pelicanparts.com/uploa...1104897785.jpg

Scott: great machining work!

I have two suggestions:

1. Don't use those three-pronged spark-plugs, just ordinary Bosch (or NGK) ones.

2. Remove sharp edge where you went trough surface and try to replicate shallow "dent" in combustion chamber roof just like original plug has. You don't want any sharp edges in your combustion chambers as they heat up easily and cause knock, which negates the benefits of twin-plugging somewhat.

Yes, your C/R will drop a little but you can probably fly-cut cylinders to compensate or even raise it a bit (now that you have twin plugs).

Cheers!

I use those three-pronged plugs with excellent results...

Scott, good work!

I cut the holes in the valve covers the other day and I was off by about 3/8". The problem was I used the upper covers to line up for the lowers and I guess since I couldn't actually slid the uppers over the studs I didn't get a good straight shot at the new plug holes. I could probably live with them, but I went ahead and ordered new covers that I'll cut correctly. I've got a rough AutoCAD drawing of the covers if you'd like for lining up for your's.

Great work. Thanks for describing the process.

Sherwood

BeepBeep,
I just haven't got around to working the combustion chamber side yet but will soon. Thanks.

David,
Thanks for the offer on the valve cover spark plug holes, it will be a while before I work them.

I spoke with a Bosch technical adviser the other day while hunting for plugs and apparently they supply plugs to CART, IRL, & NASCAR. I found it interesting that they all use the twin ground electrode type plug. The racing plugs are hand made and the ground electrodes are machined instead of welded. Here's a breakdown on the Bosch spark plug numbering system, but not all of them are available in the U.S.A.

Scott

http://forums.pelicanparts.com/uploa...1105034507.jpg

Air Injection Plug
 

David,

Where did you get the plugs that block the exhaust port holes left from the air injection pump? I guess I could make some but if they’re reasonable…

Thanks
Scott
http://forums.pelicanparts.com/uploa...1128443793.jpg

I made them. I just used some aluminum rod. Notice I threaded all the way through to the port. Just to be safe I drilled a hole through the plug and wired it to the exhaust stud. As you can tell from my signiture, I'm still not up and running so I have no info on if they stay tight or not.