3.2 top end rebuild progressing to a 3.4 - basic questions.

[mikedsilva]

Originally Posted by Cloggie

I am in the process of building an engine similar to this.

My spec is:

Mahle 98mm P/C's with the higher compression dome
Turbo 74.4 mm crankshaft
Dougherty DC 35 cams (effectively 964 with a bit more overlap)
Big port heads - dual plugged
Turbo oil pump
Carillo rods
Eisenmann 42mm heat exchangers with Cargraphic exhaust with dual cats and automated cutout
PMO ITB's
Bosch CoP's
MoTec M130 engine management system including the 964 bridges for knock sensors

It is just being assembled as we speak.

Concept I was seeking was a free breathing engine with reliability as the primary goal, particularly on autobahn where you are at high load for extended periods of time.

Absolute power was not a major goal, figured the 3.4 litres on a fairly light backdated chassis was going to be plenty of entertainment for an old guy like me.

D.

Sounds like a nice combination and will provide you exactly what you're after.

[Peter M]

Originally Posted by mikedsilva

Curious what the goal of using a GT3 crank would have been Peter?

Ah, Mike, hope you are well!

As for GT3 cranks, just a half formed daydream that a little more stroke would nice.

The reality is that I rarely drive my 3.4 nowadays and if anything, I really should redo the muffler with something more free flowing.

I generally fritter away my time with old motorcycles nowadays. Just finished the resto of my V7 Sport and have started tidying up a Katana:

[fallingat120mph]

Originally Posted by Cloggie

I am in the process of building an engine similar to this.

My spec is:

Mahle 98mm P/C's with the higher compression dome
Turbo 74.4 mm crankshaft
Dougherty DC 35 cams (effectively 964 with a bit more overlap)
Big port heads - dual plugged
Turbo oil pump
Carillo rods
Eisenmann 42mm heat exchangers with Cargraphic exhaust with dual cats and automated cutout
PMO ITB's
Bosch CoP's
MoTec M130 engine management system including the 964 bridges for knock sensors

It is just being assembled as we speak.

Concept I was seeking was a free breathing engine with reliability as the primary goal, particularly on autobahn where you are at high load for extended periods of time.

Absolute power was not a major goal, figured the 3.4 litres on a fairly light backdated chassis was going to be plenty of entertainment for an old guy like me.

D.

Now that is a build. If I was back in Germany this is what I would do also...

Hope you post the outcome, here or another thread.



Erik

[fallingat120mph]

Thanks to everyone posting so far. I am heading out from the Midwest to the Texas Hill Country Rallye tomorrow (March 12, 2025) and won't be back for a week. Hoping to see some unique set ups at the event and get a better feel for things, 3.4 wise.


Been some really great input and I will keep posting as my build progresses. I have two 3.2 engines and this build I may go with the basics but with the info provided I have a lot to research for the next build.

Thanks again to everyone at this point.

If not for my knowledge hopefully a thread like this will help others down the road...



Erik

[fallingat120mph]

Originally Posted by Peter M

I thought I laid out your choice as factually as I could Erik and also took the opportunity to address some misinformation you had been given too. There are certainly lots of happy 3.4's owners with single plug Moritz pistons and remapped Motronic ECU's on this forum so I don't think you will be disappointed.

The biggest regrets I have with my 3.4 build are:
1) Not carefully planning out my build before I started buying parts. Consequently I had to backtrack and on-sell some new parts as my plans changed. This cost money and delayed work.

2) Not buying a GT3 crank when they were still affordable!


However I certainly DON'T regret the expense of dumping the Motronic and going aftermarket ECU (Motec M130) and twin plugging among other things so I don't think you can go wrong really!

Points all taken for sure. I just didn't want to be a presumed owner who just throws money at everything for a fix/build that I had no part in. I work on all my cars but this is new territory for me so getting some shop help, especially as I am in the process of moving across country.

The regrets are what I am most interested in. As we all have come to hate the phrase "while you are in there", I feel I was very much at that crossroad in real time.

I will be happy with any conversion as I am learning a lot, but I hear a lot of the "what ifs" and "should have done this" when it comes to rebuilds and mods.


Appreciate the responses!
Erik

[fallingat120mph]

Originally Posted by Cloggie

I am in the process of building an engine similar to this.

My spec is:

Mahle 98mm P/C's with the higher compression dome
Turbo 74.4 mm crankshaft
Dougherty DC 35 cams (effectively 964 with a bit more overlap)
Big port heads - dual plugged
Turbo oil pump
Carillo rods
Eisenmann 42mm heat exchangers with Cargraphic exhaust with dual cats and automated cutout
PMO ITB's
Bosch CoP's
MoTec M130 engine management system including the 964 bridges for knock sensors

It is just being assembled as we speak.

Concept I was seeking was a free breathing engine with reliability as the primary goal, particularly on autobahn where you are at high load for extended periods of time.

Absolute power was not a major goal, figured the 3.4 litres on a fairly light backdated chassis was going to be plenty of entertainment for an old guy like me.

D.

Thanks for chiming in. Read this thread, albeit older, about the DC35's:

https://forums.pelicanparts.com/911-engine-rebuilding-forum/1039196-964-vs-dc35-cam.html

[Cloggie]

Just some engine porn to keep the faith in those waiting to get to this point.

Builder is letting me do a few things - today's task is replacing valve seals.

He also has picked up various deficiencies in some parts such as the Victor Reinz aluminum washers for the case are too soft - getting them replaced with steel and deformed nuts to replace the nylocks.

The ARP through bolt kit is very good....very nice and will last forever.

Had to clearance the Turbo pump to clear the Carillo rods. Oh yeah, bearings are all good - measured out fine and have the Calico's







D.

[85RedCarrera]

The more threads I read on the 3.2 to 3.4, the more apparent it becomes that there really are two different worlds that most of the street cars are living in:

93 octane & No Cat/no smog -or- 91 octane + Cat/smog (I’m in this group)

I’m building a 3.2 to 3.4 with 964 cams, single ignition and stock exhaust & DME, with some mild head work to bring the CR down. Not expecting a lot regarding performance gains.

Is there anyone here who has consistently passed Cal smog with a 3.2 / 3.4 and a modified chip?

[fallingat120mph]

Originally Posted by Cloggie

Just some engine porn to keep the faith in those waiting to get to this point.

Builder is letting me do a few things - today's task is replacing valve seals.

He also has picked up various deficiencies in some parts such as the Victor Reinz aluminum washers for the case are too soft - getting them replaced with steel and deformed nuts to replace the nylocks.

The ARP through bolt kit is very good....very nice and will last forever.

Had to clearance the Turbo pump to clear the Carillo rods. Oh yeah, bearings are all good - measured out fine and have the Calico's







D.

Good stuff!

Well, the 3.4 slightly used set didn't work out after careful checking...few items were not too far out of spec but neither I or the mechanic were comfortable with things...had hopes, but...

So ordered a new set of Mahle P&C and will be going forward with twin plugging plus a lot of other things...

Just ordered, and am lining up cam work.

Since I am completely doing a 180, so to speak, will post as progress moves forward.

Was okay with "keeping things simple" but guess that ship has sailed!


Erik

[fallingat120mph]

Originally Posted by Cloggie

I am in the process of building an engine similar to this.

My spec is:

Mahle 98mm P/C's with the higher compression dome
Turbo 74.4 mm crankshaft
Dougherty DC 35 cams (effectively 964 with a bit more overlap)
Big port heads - dual plugged
Turbo oil pump
Carillo rods
Eisenmann 42mm heat exchangers with Cargraphic exhaust with dual cats and automated cutout
PMO ITB's
Bosch CoP's
MoTec M130 engine management system including the 964 bridges for knock sensors

It is just being assembled as we speak.

Concept I was seeking was a free breathing engine with reliability as the primary goal, particularly on autobahn where you are at high load for extended periods of time.

Absolute power was not a major goal, figured the 3.4 litres on a fairly light backdated chassis was going to be plenty of entertainment for an old guy like me.

D.

Quick question as I am trying to research and getting a better grasp on the big picture of my new direction/build.

Through the years I see the "oil pump" and "oil cooler" upgrade and am wondering for your build if it's a necessity or just an upgrade? I ask this respectively and am just trying to study/read at what point in a 3.2 to 3.4 build an improved oil cooler or oil pump is needed, if at all?

Just reading through B. Anderson's book (Porsche 911 Performance Handbook) over the weekend...which might be more dangerous than helpful




Thanks everyone...

Erik

[mikedsilva]

Originally Posted by Cloggie

D.

What brand nose bearing is that? I didn't know they made them without the notch at the top?

[Cloggie]

Originally Posted by mikedsilva

What brand nose bearing is that? I didn't know they made them without the notch at the top?

Hi there Mike, love your channel by the way.

I just checked over the parts list and it was a Porsche bearing....now, I bought it around 2007, so things may have changed.

D.

PS: Engine is now safely back in my garage, just trial fitting all the ancillaries and figuring out how all of this goes together. Been running into dumb stuff like forgetting to rebuild the throttle plate, so off to the bead blaster and plater go those parts

[Cloggie]

Ok, slowly making progress, large PITA with the modification of the engine tin to deal with the engine moving 25 mm to the rear...that stuff is absolutely the worst sheet metal on this planet.

The wiring harness is all fabbed up along with the mounting plate for the Motec dual lambda CANBUS splitter, the MAP and the exhaust cut-out valve. Had to fiddle with the mounting of the manifold for the vacuum ports and the heater tube was a ***** with the Eisenmann/CarGraphic + cats + exhaust valve combo.

Now I am fighting putting the air horns into the air cleaner, how the hell are you supposed to tighten up those 8 mm nuts that retain the horns and the lower air cleaner housings?

There is absolutely no room for a nut driver, wrench, socket or whatever...any ideas? What's the trick?


Anyway, here are the latest pics...going out to put in the vacuum takeoff for the cutouts including check valve plus some minor parts to be bolted on.








D.

[Henry Schmidt]

Originally Posted by Cloggie

Now I am fighting putting the air horns into the air cleaner, how the hell are you supposed to tighten up those 8 mm nuts that retain the horns and the lower air cleaner housings?

There is absolutely no room for a nut driver, wrench, socket or whatever...any ideas? What's the trick?

.

K Nuts (AKA Jet nuts) offer unusually small heads on a flanged nut. Install them with a 1/4" universal socket on an extension.

[Cloggie]

Originally Posted by Henry Schmidt

K Nuts (AKA Jet nuts) offer unusually small heads on a flanged nut. Install them with a 1/4" universal socket on an extension.

I will give that a go....thank you so much!

Douwe

[Cloggie]

Henry, your suggestion was spot on. Bought the swiveled socket just like your picture - I did not know such things existed and the nuts went on quite easily.

Air cleaner now fitted, probably will cut down the snorkel a bit, although Grok tells me there is no material difference in air flow between the 57 mm diameter as it is versus the 77mm diameter I want to cut it down to.





D.

[Henry Schmidt]

Grok is an idiot.
That snorkel will work as an air restricter much like the restricters used on racing engines ti limit horse power output.
Keep in mind that the air filter housing your using was designed as a silenser on engines making less than 180hp.
Here are two ways we've handled the issue of restrictive air flow.

[Cloggie]

Thanks again Henry. It seemed a little counterintuitive as that hole in the snorkel looks awfully tiny compared to the 6 x 46mm throats on the PMO's.

I will probably cut the snorkel down to just before the 90 degree bend starts - it rains lots here and I sorta think a little bit of snorkel will help keep some of the water out.

Its plastic anyway, easy to cut and form....

D.

[Henry Schmidt]

Originally Posted by Cloggie

Thanks again Henry. It seemed a little counterintuitive as that hole in the snorkel looks awfully tiny compared to the 6 x 46mm throats on the PMO's.

I will probably cut the snorkel down to just before the 90 degree bend starts - it rains lots here and I sorta think a little bit of snorkel will help keep some of the water out.

Its plastic anyway, easy to cut and form....

D.

The math calculation is pretty simple
Venturi 46mm=1662mm2 x 6 = 9,972mm2
The snorkel looks to be about 60mm = 2827.4 mm2
Of course the CFM of the engine is not in direct correlation with venturi size.

Something else we've done is to cut out the opposite end of the filter housing, moved the breather hose attachment and welded in a screen. the noise level in the car goes up but the engine can breath.

I would save the intact snorkel and look for a snorkel from a 72-73 US MFI. They are already short. Intact intake parts are getting harder to find. Maybe someone is looking for your snorkel for their concours project.

[targa72e]

I tested the effect of the inlet on the dyno. It is a restriction. You can see the results in this post

https://forums.pelicanparts.com/porsche-911-technical-forum/1151593-dyno-summary-testing-early-2-4l-2-5l.html

John