3.3 turbo project wrap up! Need help!

[Levan]

Dear Gentleman,

First of all I would like to thank Wayne R. Dempsey for the extremely helpful book! Awesome!

My car is 1988 PORSCHE 911 930 3.3l Turbo with 77.000 miles on the odometer. This car was presented to me by my father. This car is in our family since 1992. This is going to be first rebuild ever of this engine. The reason WHY I’m going to rebuild is one cylinder burn through due to the “over boost”.

Hence, I’ve got hundreds of questions 

My train of thoughts was about to:
1) Buy 3.4 (instead 3.3) original MAHLE piston and cylinder set
2) Buy full rebuild kit – according to the Wayne’s book instructions
3) Buy new turbocharger
4) Buy new exhaust muffler and possibly heat exchangers
5) To give some machine work to cylinder heads and crankcase

It’s like a first step. So I wonder – where I can buy all this stuff (possible Pelican?) and who can hlp me with rebuild process (@Wayne, I would be grateful if you could consult me).

So first of all I would like to wrap up the purchase list and define where machine work could be done.

Thank you in advance,

-Levan

[sand_man]

Welcome. I think establishing a relationship with a knowledgeable engine builder/machinist is critical to your project. Now is the time to consider your plans for the engine/car so the parts can be properly matched. Plans for EFI? Track car? Daily driver? Garage queen? I'm not sure where you're located, but some shops known for quality work:
-Supertec Performance (Henry Schmidt, regularly posts here)
-Performance Developments (Neil Harvey - shop that did my machine work)
-EBS (Engine Builder Supply)
-JB Racing (Mike Bruns)
-Ollies
-Local shops/specialists in your area experienced with air cooled Porsche engines

As for Ps&Cs, Mahles are definitely considered one of the standards. The 98mm 3.4L are "slip in" and don't require machining to the case spigots. Another nice option are the LN Engineering "Nikkies" cylinders with JE Racing pistons. Whatever you choose here, I think it's worthwhile to get fully finned cylinders...the stock 930 3.3L cylinders have no cooling fins on the top.

ARP rod bolts are something else that should be considered. The factory bolts don't like to be revved.

"Upgraded" headstuds are another "while you're in there" item. Lots of choices and some controversy:
-Performance Developments
-Supertec
-ARP (what I run on mine)
-Factory 993TT

Cams...generally considered the heart of the engine. I went with SC cams in mine...sort of a tired and true "typical" grind for a street driven 930. But there are other options, including custom grinds. Discuss with your specialist.

Exhaust systems make a serious difference on these engines. I would discuss with user RarelyL8. He has teamed up with M&K and offers a nice SSI option for our engines. B&B, GHL, Fabspeed, Schnell and OBX also make headers/exhausts/mufflers for our engines.

As for turbos, Ultimate Motorwerks and Imagine Auto offer some nice K27 variants that are light years ahead of the factory 3LDZ turbo. I run the K27HFS on mine. One thing I'll mention about the turbo, make sure you run your original turbo during the break-in stages of your new engine. It is possible to FOD (Foreign Object Damage, from new header welding slag) a turbo during these stages...no point in wasting a nice new turbo!

If you're planning to track this car (lot's of high RPM driving), upgraded valve springs and retainers should be considered.

As for heads, any future plans for twin plug ignition? Now is a good time to have the extra set of spark plug holes drilled...you can always plug them until you are ready for the other ignition parts. There is also room for improved intake flow...something to discuss with the machinist.

Others will chime in...best of luck!

[WERK I]

Questions for you, Levan.
What are your intentions with the car? What HP level are you seeking?
Before we inundate you with recommendations, tell us where you want to go.
And don't forget your suspension and brakes. They're going on 21 years and things tend to get a little sloppy over time.

[sand_man]

Also, do you know what caused the "overboost", to begin with? Faulty wastegate? Larger than stock wastegate spring? Was the overboost sensor diasabled? Ignition/fueling issues?

[Levan]

Originally Posted by WERK-I

Questions for you, Levan.
What are your intentions with the car? What HP level are you seeking?
Before we inundate you with recommendations, tell us where you want to go.
And don't forget your suspension and brakes. They're going on 21 years and things tend to get a little sloppy over time.

I'm looking for weekend race car setup. But on the other hand - I believe it to stay more or less stock one. My turbo has 330hp in stock, so 380-400 should be convenient.

To say truth, I'm not sure what was the reason of engine fail. If i'm not missing something- waste gate of exhaust muffler caused it.

I asked my serviceman to check the camshaft lately - and I've got an answer that it's in mint condition, and there is no need to order oversize bearings even.

[WERK I]

Well, lots of options available to you in the piston/cylinder department. There's the standard Mahle 3.4 pistons and cylinders, Nickies cylinders w/JE pistons and there's the EBS Racing cylinders w/steel liners and JE pistons (DonE on the board has been using these with good success). I recommend 7.5 to 8.0 compression ratio, highly recommend twin plug ignition for street/track for margin of safety.

Internals- ARP rod bolts are a must. Head studs...I recommend the factory 993TT head studs, but Supertec and ARP studs are available from our host.
Cams have to be updated. The 930 cams are marginal performance cams and suited for the standard 3LDZ turbo. Go with, at minimum, SC grind but 364, EVO grinds are better.

Turbo - A Garrett GT350 or Ultimate Motorwerks K-27 hybrids (S or HFS...it's hard to keep track of nomenclature). The Garrett turbo's will require more fabbing....mounting hardware and oil line. TurboKraft sells such kits.
Headers - MK has a kit that uses SSI heat exchangers and the most reliable setup out there, B&B, GHL have headers with or without heater boxes.

IC - The stock IC will not reduce heat sufficiently and requires upgrade. If you can get your hands on a factory 964 IC, great. Other than that there are other units out there. Don't have enough experience with any of them to recommend. Kokeln was a good choice years ago, but Quality Control has been lacking in newer units.
Wastegate- If you can have the factory WG rebuilt, great, but parts are getting scarce for these units. Tial 46mm are great, and damn near bullet-proof.
Fuel injection - Two choices. The Brian Leask adjustable Warm Up regulator or the DigiWUR by UniTools. Get the engine dyno'd after engine is modded to get good AFR's across the RPM band.

Suspension - This will give you the most bang-for-the-buck. Our host and Elephant Racing has some great packages that will really bring your chassis to life. In factory trim, these cars understeer pretty bad, but with some changes, you can get a more neutral car. Get your car aligned and corner balanced after you update your chassis!

Brakes - Lots of options, can't recommend one brand over another. Search on this site for threads on the subject. (930 brake pads). Things to keep in mind....dust, noise, rotor wear.

Tires - Ultra Performance tires are a must. The list is incredible in length.

The tab will easily go over $10K, but what a car this will be. Changes the whole character of the beast.

[sand_man]

Originally Posted by WERK-I

Well, lots of options available to you in the piston/cylinder department. There's the standard Mahle 3.4 pistons and cylinders, Nickies cylinders w/JE pistons and there's the EBS Racing cylinders w/steel liners and JE pistons (DonE on the board has been using these with good success).

Don is actually using the JB Racing cylinders, which have aluminum fins and iron sleeves.

I agree, this easily goes over $10K...EASILY! I still get the shakes when I think back on it! It sure is a gratifying when it's done, though!

[Levan]

WERK-I,
Thank you for the prompt answer. As for me I would rather prefer to stay more or less original. Hence, 3.3 to 3.4 bore is the only convenient solution for me. Is it okay to keep original rods or forged are MUST?

In studs there is clear to me – I’ll take RaceWare of ARP as a kit. I’m not going to keep Dilavar studs.

What changed I will have to perform, if I decide to convert heads to twin spark setup?

[sand_man]

Originally Posted by Levan

WERK-I,
Thank you for the prompt answer. As for me I would rather prefer to stay more or less original. Hence, 3.3 to 3.4 bore is the only convenient solution for me. Is it okay to keep original rods or forged are MUST?

In studs there is clear to me – I’ll take RaceWare of ARP as a kit. I’m not going to keep Dilavar studs.

What changed I will have to perform, if I decide to convert heads to twin spark setup?

The stock rods are fine, just replace the rod bolts with ARPs.

I've got ARP headstuds in mine, and have had zero issues. Same for many others, all with similar builds. However, the factory 993TT headstuds are what many "experts" are using. I can't recall if the 993TTs are Dilivar or steel...

[WERK I]

Originally Posted by Levan

WERK-I,
Thank you for the prompt answer. As for me I would rather prefer to stay more or less original. Hence, 3.3 to 3.4 bore is the only convenient solution for me. Is it okay to keep original rods or forged are MUST?

In studs there is clear to me – I’ll take RaceWare of ARP as a kit. I’m not going to keep Dilavar studs.

What changed I will have to perform, if I decide to convert heads to twin spark setup?

What Sand_man said: +1
The 993tt studs are an improved dilavar alloy. Handle 600BHP with no problems. If you go with a twin plug ignition, you have to modify the heads and lower valve covers, of course. If you do, use the smaller plugs. The ignition itself has a couple of options. The factory twin plug distributor ignition, but it will require work to get to work. I went with the Electromotive ignition with twin plug/crank fire sensor. It's extremely reliable........good insurance if you're going to be seeing boost levels 1.0+. Either option is not cheap by any means, but what is on these cars.

[Levan]

Nightmare!
I took my time to decide setup. So I'm gonna stay completely original (MAHLE 3.3 displacement even), single sparked heads and original camshafts 

My mechanic tested the crankshaft. I was told that there is no need to order oversize bearings even. Should I perform any machine work over the case?
Is oil bypass modification applicable for 1988 turbo engine? Any suggestions in this case?

Thanks in advance,

[WERK I]

Originally Posted by Levan

Nightmare!
I took my time to decide setup. So I'm gonna stay completely original (MAHLE 3.3 displacement even), single sparked heads and original camshafts 

My mechanic tested the crankshaft. I was told that there is no need to order oversize bearings even. Should I perform any machine work over the case?
Is oil bypass modification applicable for 1988 turbo engine? Any suggestions in this case?

Thanks in advance,

No case work or oil bypass mods are necessary for these engines. I would spend the money in case work on cams (SC grind) and ARP rod bolts in case you decide to up your hp in the future. That way you will not have to go back in there. My $0.02

[Levan]

In fact there are two options of MAHLE piston and cylinder set: 7.1:1 and 7.5:1
Which is more preferable?

[osiris2600]

Originally Posted by WERK-I

I recommend 7.5 to 8.0 compression ratio, highly recommend twin plug ignition for street/track for margin of safety.

I've been wondering this since I've been on this forum. How does one go about selecting the correct compression ratio? I understand the concept of compression ratio being the ratio of volume of air that is compressed from the bottom of the stroke to tdc. But how does one tell which config is best? If your running a turbo motor with about 1.3 bar should the comp ratio be lower, say around 7 or in the 9.5 range?

[Flieger]

Basically, the higher compression ratio you can run, the better. Higher compression ratios need higher octane to prevent pre-ignition so the fuel quality is your limiting factor. Twin-plug ignition also helps by starting 2 flame-fronts at once so the timing can be run more critically.

On naturally-aspirated engines, volumetric efficiency goes up with increasing compression ratio. This means that you make more torque for the same fuel and displacement if you have a high compression ratio (like a diesel).

Turbo cars complicate this; there is a graph comparing boost and compression ratio.

Low compression ratios on turbos allow more boost before the engine blows apart or pre-ignites. Off boost, though, the engine is weak and inefficient. On boost, the turbo makes cylinder pressure more efficiently (turbine using waste exhaust heat) than a high compression ratio. This means top power is greater and more efficient for a turbo, low compression, than a high compression naturally aspirated motor.

A downside of high compression ratios is they generally require longer strokes, which put more stress on the sides of the cylinders and can have vibrational problems on the crankshaft limiting rpms.

Also, high compression ratios achieved with high-dome pistons can have valve-piston interference at high rpms especially. The piston dome also splits the hemispherical combstion chamber. This causes half of the chamber to be shielded from the spark plug and possible ignite uncontrolled.


You must compare your fuel quality, off-boost power wants, and on-boost power wants to decide on compression ratio.

[Levan]

Okay, finally I have my engine teared down.

Gentleman, please have a look:







If anyone has on idea what was the cause or this fault, you're welcome.

At last, I have checked my crankshaft maximum runout is 0.01mm (70 000 miles on a dial). So it looks fine. I'm going to get it polished by Wednesday.


Thank you in advance,

-Levan

[Levan]

I have another one question regarding cylinder heads.
I've found quite strange device, connected into cylinder head - show on the picture. I can't find such a part in PORSCHE parts catalog



Thanks,
-Levan

[sand_man]

The circled pipe at the bottom of the cylinder head is for the air injection system used by Porsche for smog regulation purposes. If these parts are not needed in your area to pass a visual inspection, you can remove these injectors (and the related parts: injection pump, plumbing, etc) and use threaded plugs (like a cap screw) to fill the cylinder head holes.

The longish studs at the other end of your cylinder head (the other circle) are for the intake manifold and fuel injector blocks.

[ischmitz]

It looks like knocking has destroyed the ring lands and the rings gave out soon thereafter. This scoffed the cylinder wall enough for it to create a local hotspot where subsequent blowby and pre-ignition resulted in a local meltdown. And the rest is history.

Knocking could have been a result of many things such as too much boost, bad fuel, wrong timing, oil in the intake due to a leaking turbo bearing, etc.

When you look for advise on machine work and general assistance it would help to let us know where you are located. Each area has its local heros.

Cheers,
Ingo