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350HP930 06-19-2003 06:04 PM

Rebuilding My 930
Well after 5 years of ownership and about 130,000 miles (70K of which are mine) I have recently dropped and broken down my 930 motor for a complete rebuild. I was hoping to put it off a bit longer but the starter ring gear lost a few teeth so the motor had to come out anyways. Its been needing a rering and reseal for a while.

Thanks to recent economic trends I will have to pull off my rebuild and mods on a tight budget. Fortunatley have access to a high end machince shop and porsche dealer service area due to my employment and engineering backgroud (BS in Aerospace Engineering, U of F, Class of 95) so I do not need to pay for anything but parts and dyno time.

Here is what I am planning on doing to extend my existing mods. I would appreciate any input people would like to give me on my project.

All the hardware looks beautiful except for a mild scratch in one cylinder. Everything mics to about 0.0005 of factory specs.

For this reason I am just going to rering the cylinders. I am seriously contemplating going with gapless rings.

Here is a list of most of the other stuff I have on my todo/toget list. (Updated 2/4/05)

ARP rod bolts and cylinder studs
All harware flycut and/or lapped and rods resized
New bearings and gaskets
New chains and tensioners
New valve guides and valve job
New performance cams, and rocker shaft seals
Slight compression bump
8:39 Ring & Pinion
Carrera Intake Manifold
Megasquirt II EFI
Distributorless Igntion
HKS EVC IV (Electronic Boost Controller)
Boring and Porting the Heads and Intake

My current spreadsheet for my project shows that the total cost for all this will about $8.5K.

I figure I have a few months before I will have all the time and money I need to pull this off. (As the thread shows I suffered from quite a bit of project creep from the 'while you are in there' phenomena)

I look forward to the wisdom this board is sure to bring me. (And it has brought me much since I started this thread)


350HP930 06-19-2003 06:06 PM

Pics for your amusement . . .

Motor Drop

350HP930 06-19-2003 06:13 PM

Some parts and pieces laying around . . .

Wayne 962 06-20-2003 12:18 AM

Sounds like your budget may need some revision? Do you have a copy of the Engine Rebuild book? Did you measure the ovality of the cylinders?


350HP930 06-20-2003 03:15 AM


Originally posted by Wayne at Pelican Parts
Sounds like your budget may need some revision? Do you have a copy of the Engine Rebuild book? Did you measure the ovality of the cylinders?


Yup, I measured the cylinders.

After 20 years of rebuilding automotive, motorcycle and aircraft engines I'm not sure if the ERB will reveal anything to me, but I have concidered getting it.

And while there might be something that I need to add to my list as time goes on, its pretty much on the mark.

For example, while you guys want $165 for cam chain tensioners, I can get them for $130 from porsche (love that employee discount).

Don't worry though, I have spent a lot of money with you guys over the years. I'm sure their might be something I get from you guys this time around. ;)

ChrisBennet 06-20-2003 03:45 AM

I don't know if I'm being overly anal but I always change the sprockets when I change the chain and I replace the keepers and retainers when I replace the valves.

5axis 06-20-2003 08:28 AM

Re: Rebuilding My 930

Originally posted by 350HP930
993 Turbo head studs
This is the only thing on the list I wonder about. Why not ARP or raceware? I can't see building a turbo motor and not crossing the t's and dotting the i's.

WERK I 06-20-2003 09:36 AM

Boattailing the cylinder case webs, eye-browing the cylinder bores, knife-edging the crank are nice horsepower additions(20HP is the talk). I was on a budget too(then again, aren't we all) and didin't go with the ARP head studs. Chose the 993 turbo studs. If they're good for 500+HP 993 turbo's, they're good enough for me. I hope your head job includes new springs, retainers and locks.
Are you going to retain the stock intercooler, exhaust? Highly recommend going to Kokeln IC, GHL exhaust system and upgrading to K27 turbo(7006). Remarkable differance in turbo response.

350HP930 06-20-2003 04:38 PM

Actually I do not want to do any additional machining to the case than what is necessary to true up the appropriate surfaces and bores.

Supposedly windage losses only get really bad at very high RPMs (like 6K RPM and up) and my motor is going to be set up for between 3K RPM and 6,500 RPM.

High revs are some of the most stressful forces any motor has to deal with anyways and I want to keep those stresses minimised.

If by eyebrowing you mean notching the cylinders near the valves I don't really see how there is much obstruction in the stock valve geometry. Perhaps you could explain what could be done there.

I see you have already answered the question about why I am using the 993 studs. I trust the recently engineered solution from the air cooled experts at porsche more than I do a company that is mostly focussed on making studs for a lot of water cooled equipment. I do trust their rod assembly hardware though.

The fact that a set only costs $168 is also very nice too compared to the cost of the aftermarket head studs.

If they spec out OK I may reuse a few valvetrain components I am replacing the springs and the retainer clips.

I have remanufactured enough motors to know what is suitable for additional service and what is likely to not survive past the 2,000 hour mark.

As a result of the low budget I will be reusing all my old factory plumbing, with the exception of my K&N intake, K27 and a pass through muffler which have served me well for several years. I would love to upgrade the exhaust and intercooler, but my current mod list will bring me more performance than those will.

Between the piggy back fuel injection system I will use to push the power past the 350 HP CIS limit and some other 'optimizations' this is a project that will attempt to get at least 400 HP at the back wheels from nothing more than a warmed over CIS 930 with cams and an additional fuel injector.

350HP930 06-20-2003 04:53 PM


Originally posted by ChrisBennet
I don't know if I'm being overly anal but I always change the sprockets when I change the chain and I replace the keepers and retainers when I replace the valves.

Chains yes, sprokets no.

Chains will stretch and sprokets will wear, but the wear on a sproket running a minimally stretched chain is negligible.

A chain that has stretched too far can decimate a sprocket.

After years of working on motorcycles you learn a few tricks about inspecting chains and sprockets and get an eye for judging what is good and bad. Let me just say that I was amazed at the condition of the cam chains and sprockets in my motor.

As far as recycling valvetrain components go, retainers yes, keepers no.

Its like how when you rebuild a tranny you may change syncros, but if they are still in spec you don't change your gears.

TimT 06-20-2003 04:56 PM


A different type of intake system with engine management would get him over that 475 horsepower C.I.S hump
I got that quote from an article in my local PCA mag

with CIS you can see some serious hp.. with the mods you listed you will probably see over 350hp easily

Try SC sport cams, coupled with opened up ports.

you may want to open the dia of the cis manifold ( perhaps extrude hone it) and the phenolic blocks cant be opened that much, so get a set of aluminum blocks... with the intake pathe free of restrictions and a good cam the power will be there.

350HP930 06-20-2003 06:01 PM

I have heard that a cleaned up 930 CIS system can flow about 500 HP worth of air but that the best the distributor, lines and injectors can do is about 400 HP worth of fuel.

I figure that the 300 HP of CIS fuel plus plus another 200 HP of EFI fuel should allow me to maximise what my modified plumbing will allow.

Plus the HKS AIC III will allow me to tune my A/F mix over the different boost and rpm ranges for the best possible output.

TimT 06-20-2003 06:07 PM

'79 fuel dist will make about 450 hp.. at some point after that they had different fuel systems for US vs Euro cars..

One thing missing in your list of things to do , is....
install a good EGT gauge..its a must have!

john walker's workshop 06-20-2003 06:26 PM

you don't say whether you are versed in 911 rebuilding, or just have done a lot of engines. 911s are different enough, that wayne's book is a necessity if you want to succeed on the first attempt, or do it again. no substitute for all the hard learned info in that book. one good trick learned is worth the price.

350HP930 06-20-2003 08:21 PM

OK, you got me sold. I have done quite a few similar engines but never a porsche flat six.

And good point about the EGT. I am doing one better

The only additional guages I am running in addition to the giant boost guage where the clock used to be will be these two guages in pods on the pillar.

Mike the mechanic 06-20-2003 09:05 PM

Nice project! I can't help but notice that jack you have holding up your engine and tranny. I want one! I am really starting to do many 911 at the shop, and was recently wondering what the dealer uses to remove an engine... Is that it?

Wayne 962 06-21-2003 12:09 AM

JW said it all - I specifically wrote the Engine Rebuild Book with all of those tips and tricks in mind. I'll offer you a money-back guarantee if you're not satisfied and don't think it's worth the $35 for the book and CD...


350HP930 06-21-2003 05:40 AM


Originally posted by Mike the mechanic
Nice project! I can't help but notice that jack you have holding up your engine and tranny. I want one! I am really starting to do many 911 at the shop, and was recently wondering what the dealer uses to remove an engine... Is that it?
We have a couple different jacks for different porsche models, but thats the one we have for the older 911s and 930s.

The jack is an OMC tranny jack with a special adaptor plate for the older air cooled motors.

The angle is adjustable on the lift plate and there are casters at all four ends which makes getting the shifter shaft in and out of the chassis and the motor in and out a lot easier than the rolling shop table method I used to use.

For the newer porsches the shop also has a table lift which is a rolling table on a scissor jack mechanism that can go up to about 6' in height.

Lets just say this makes the daily routing of changing motors out as easy as it gets.

WERK I 06-21-2003 06:31 AM

If you haven't acquired an A/F gauge, you might want to take a look at this product from Nordskog Performance Products;
It has some nice features such as memory for lean and rich recall. It also doesn't use led's which look a little "ricey". Gauge appearance fits in nicely with existing VDO look. Not affiliated with Nordskog, just my $0.02. I found the unit at Summit Racing, pricing competitive.

350HP930 06-21-2003 07:58 AM

Damn, that is a beautiful A/F guage.

If not for the fact that I want to upgrade (I currently have a cheap intellitronics unit on a pillar pod) to the J&S unit so I can see when the engine is beginning to detonate for tuning purposes I would jump on that in a heartbeat.

Thanks for the info anyways though.

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