Street Performance 3.2 Rebuild

[drmanberrys]

Hi I'm Mike,

I live in Brisbane, Australia and own a 1970 911 that has been modified to resemble a 964 American Roadster.



I have had to do a rebuild on the 3.2 as it spun a big end bearing on number 2 cylinder. After stripping the engine completely I was releaved to see no real damage has been done other than some scoring on the crank journal and the conrod.

While I have the engine apart I have decided to do an upgrade to gain more performance. I don't want to go down the twin plug path at this point in time but would like to get the most out of it without going overboard.

I have the book "how to Rebuild and Modify Porsche Engines 1966 - 1989" and was looking at the recommended 10.3:1 Mahl pistons and cylinders to make it Euro specs. Also back dating the exhaust system to an SSI and Dansk twin in twin out muffler.

As far as other possibilities I am unsure what I should do especially as far as cams go. I am going to send the heads out for a reco and port matching and polishing and have a Motronic injection system and was considering a chip of some sort but not sure what to do here either.

Any help would be greatly appreciated.

Cheers Mike

[AlfonsoR]

The only language we know here is "go over-board all the time, as often as possible and pray the wife doesn't find out". :-) Just kidding...

OK, i'll throw out the first question, what is your budget?

And a couple of suggestions:
1. Since you want to stay single plug, look at another thread by "dipso" 10.5 CR on single plug. Some really good advise in a relatively short thread.

2. There is some good data on Steve Wongs site, 911 chips. Read through the dyno charts and the different mods some folks have done. This might give you an idea of what to expect for certain mods. 911Chips - Porsche Dyno Runs

[drmanberrys]

Cheers for the reply AlfonsoR,

I will check out the thread you suggested and the website concerning the chips.

As for the budget, I am looking to spend up to $15000 on the upgrade which part of this includes a new clutch, WEVO 915 Shift Kit and various tools to help complete the job. So I would say 13K just for the engine rebuild. I will be doing the assembly myself but I am yet to send the heads, crank, case, rods etc. for machining. If I go over budget so be it but I would like to stay closeish to this figure.

As far as the wife goes she is pretty good about this kind of thing so I don't have to hide anything. She's a keeper

[drmanberrys]

I just had a look at the thread by dipso and realised that I had read this just before I made my post. I considered what was said in this post at the time but thought as I run on 98 octane I would be able to get away with the higher compression ratio. Also in Waynes Top Engine Picks from the book he states that no additional upgrades are required for the 10.3:1 Euro Upgrade.

Being new to Porsche engine rebuilds I can only go by the information I have (Waynes book) but if people in the know suggest not increasing my CR then I will certainly listen.

I would like to do the twin plug upgrade at some stage but but after reading the different ways of going about this I decided that it could wait for another day until I do more research (and save more funds).

[drmanberrys]

After reading many threads on the subject of twin plug systems I am very overwhelmed by the array of possible combinations but would really like to pursue this option in the future.

If I was to go down the twin plug rout, would it be advisable to have the machining done on the heads and lower valve covers and screw the plugs in until I am ready to change the distributor and other components?

Primarily I want to focus on the engine rebuild but would like to have this machining done now to save having to pull the engine out again if this is a possible option.

[Geronimo '74]

I just finished my rebuild.
It's a ROW car so I already had the 10.3:1 CR.
I added 964 cams, SSI's and an M&K dual in out muffler. The Wong chip was already in there.
I could have tried to get more out of it but for a street car, this will do nicely.
It has about 50 miles on it since I got it back from the shop. So it's not broken in yet. But I can feel the improvement over stock very clearly.
I say go for it!

When I Pm'ed Camgrinder, he suggested 964 cams or 993 supersport. I went with the 964 because I found a set that was like new and very cheap.

[drmanberrys]

Cheers Geronimo '74,

Sounds similar to the road I was heading down, just wasn't sure what cams or cam profiles to go with. Good to know about the Wong chip as well, this being another grey area for me.

Does your engine have a twin plug setup?

After ploughing through this forum and others I am tempted to go for a more aggressive rebuild but not ready to upgrade the transmission if it can't handle the grunt. So need to take baby steps and do this in a logical ordered steps that will still allow me to get the car back on the road soon (having major withdrawals).

I have been looking at Clewett Engineering's Individual throttle body dual plug kit, has anybody had anything to do with this system and what other engine modifications would be required or am I just going overboard?

[AlfonsoR]

Do you already have something in mind for your rebuild? If all you need to do is turn down your rod journals, you may want to:
1. keep the pistons and cylinders you have
2. buy a nice set of rods R&R, Carillo, Pauter - $1800
3. send your heads to someone who is really good, like Steve Weiner or Xtreme Heads (not for increasing flow but for optimizing characteristics such as tumble, swirl, etc
4. install a set of PMO carbs - $4,000
5. Cams and springs ???

I guess my point is, if you really want a decent increase in power, it might be a better value (if you can re-use your Ps&Cs) to spend some cash on improving the breathing capability with carbs. ITB injection would be nice too but more money, I believe and more complex. Said another way, Motronic & the intake plenum are the biggest bottle necks to making power. The upgraded rods are just insurance for over revs.

Just throwing some ideas out there, I could be wrong. I need to rebuild my engine too (first time too) and you're right, the combinations are endless.

[drmanberrys]

AlfonsoR when I first stripped the engine to assess where I was at in terms of damage because of the spun big end bearing I thought a quick hone, re-ring, bearings etc.

Then I had a beer and thought what do I really want out of this rebuild and decided a near new engine was the end goal. After more deliberation (beers) and more research I thought Waynes Euro upgrade with a few other mods was for me.

Now having decided after much research to go down the twin plug direction I am of the opinion that I may as well increase the displacement which brings up other issues, my biggest concern being the Motronic Intake plenums and throttle body.

Also being a computer nerd I would like to stay with injection and a programmable engine management system (more research required).

Having read a great article at the European Car Website (a long article over 5 posts which are hard to navigate but I got there in the end).

Porsche 911 SC Carrera Engine Buildup Project Car - European car Magazine

I am really liking the sound of this rebuild which also gave a pdf of parts used and part numbers.

I am leaning towards this rebuild as a base and making several other changes the author of the article could not make due to smog restrictions that will not effect me where I live in Australia.

I am getting closer to making the theory engine I believe would be the one for me but still want to explore all possibilities before I send things out to be machined.

Here are some pics of where I'm at, I will post more when there are more pics but I am planning on taking a lot of time to plan and implement this rebuild.

Engine Out.




What a dirty dirty engine.



Most parts cleaned, painted or polished.

[Geronimo '74]

Dr,

I was planning to go the 3.4 route too but my budget quickly killed that dream.

Whatever you do, make sure your gearbox is in good working order (if it isn't already)
You won't enjoy your the upgraded engine if it is married to a crappy trans...

[drmanberrys]

Hey G-man I have given this some thought as well, my tranny is a 915 that is still in the car but will be out as soon as the rain stops (fingers crossed tomorrow) for inspection.

Hopefully the 915 will be up to the task but only time will tell.

[Geronimo '74]

If you are going to 3.4, with some other mods, and are keeping the 915 tranny, it needs to be in good shape.
Is it a younger model 915? WitH the additional oil cooler?
I don't know if the older gearboxes will like the extra horses and torque.

[drmanberrys]

Being new to the Porsche world I had no idea there was other versions of the 915 trans.

I was in the back of the car yesterday and did notice a cooler coming off the left side of the trans. So I am now assuming that this makes mine the older version.

I had not planned doing the trans during this rebuild and will just have to see how long it lasts once I am finished. It should be OK during the run in stage but after that it probably won't last too long and I will be doing the G50 transplant sooner rather than later.

[Geronimo '74]

I'm not an expert on 915 gearboxes either.
It just seems logical that the "youngest" versions should be more capable dealing with higher HP numbers. The added oilcooler from the latest versions would help too.
A G50 will be more than strong enough, I reckon.

The later versions 915 had the oilcooler.
(I believe '86 and onwards)

[Geronimo '74]

If you are planning to switch. It's not a plug and play job...

Can you replace a 915 trans with a g50 easily

[drmanberrys]

Thanks G-man for the insight I obviously read your post wrong (stupid me ), so my trans will probably last a little longer and might still be worth doing the Wevo sift kit upgrade.

I would eventually like to upgrade to the G50 with a hydraulic clutch (at the moment the pedal is so darn heavy).

Thanks again for your help.

[drmanberrys]

OK for those interested, the rain stopped just long enough for me to remove the trans and axles.

The photo does not show all the crud on the trans because I degreased and hosed off before I started but boy was it covered in oil none of which was from the transmission itself.

Had a quick look at the oil (still have to drain for a proper inspection) and I was surprised how good it looked and smelled.

A dirty dirty tranny.



And after some love with more degreaser, an old tooth brush and the garden hose with a high pressure nipple.

Cleanish tranny

[drmanberrys]

And here is how bad I looked after wading through the crud to remove the trans.

[gsxrken]

Originally Posted by drmanberrys

And here is how bad I looked after wading through the crud to remove the trans.

Here in the US we can buy latex surgical gloves. An entire box of them isn't $10...

[Flieger]

Well done, mate. The grease smears are badges of honor.