3.2 to 3.4

[stubble88]

Anyone have a list of what’s needed to go from 3.2 to 3.4?
For starters I have used:
964 dizzy
Twin plug heads
98 mm cyl and pistons
964 cams?
Can you use 3.2 injection??
3.2 motronic??

I have to rebuild my motor and I’m wondering what the added costs would be.
I searched this area and found nothing.

Thanks

[mepstein]

Yea, we recently built a 3.2 to 3.4 twin plug, 964 distributor, big valve heads, etc. the 3.2 to 3.4 only requires the larger p&c’s. You don’t have to twin plug it to go bigger. We stick with the stock motronic but remapped a custom chip. You’re not gong to find a listed price on the internet to make the changes but parts are easy to price out and if you are doing the work yourself, then labor is “free”. If you are sending it out, then labor is whatever your builder charges, there’s no standard rate.

We rebuilt the transmission with custom gears. I think that mod tends to get overlooked when building a hot rod. It’s not cheap but makes a big difference on the overall drivability of the car.

[robblr]

Originally Posted by mepstein

Yea, we recently built a 3.2 to 3.4 twin plug, 964 distributor, big valve heads, etc. the 3.2 to 3.4 only requires the larger p&c’s. You don’t have to twin plug it to go bigger. We stick with the stock motronic but remapped a custom chip. You’re not gong to find a listed price on the internet to make the changes but parts are easy to price out and if you are doing the work yourself, then labor is “free”. If you are sending it out, then labor is whatever your builder charges, there’s no standard rate.

We rebuilt the transmission with custom gears. I think that mod tends to get overlooked when building a hot rod. It’s not cheap but makes a big difference on the overall drivability of the car.

As the proud owner of this monster, I'm here to tell you you will not regret your decision. And ditto what Mark said about the transmission. Short gearing keeps the power where you want it. It's hard for me to imagine this thing with the stock 915.

[PeteKz]

Check with Steve Wong for a new chip too. Increasing the displacement slightly wont' affect the Motronic much, but adding the twin plug heads will.

[Tad240]

Originally Posted by robblr

As the proud owner of this monster, I'm here to tell you you will not regret your decision. And ditto what Mark said about the transmission. Short gearing keeps the power where you want it. It's hard for me to imagine this thing with the stock 915.

Can you share any more information about the gearing changes you made vs the stock 915? Would love to know more and how it compares.

[mepstein]

Yes, the person who does our custom chips has an amazing amount of experience. The engine feels nothing like stock - in a good way. It’s pretty amazing what you can do with a 40 year old motor and efi system.

[mepstein]

Originally Posted by Tad240

Can you share any more information about the gearing changes you made vs the stock 915? Would love to know more and how it compares.

We used a 904 style 915 main shaft, LSD and geared it to the tire size, engine size and redline. Current redline is 6800 but can be raised to 7200 if the customer wants. I drove it a bunch before handing it off. I’m building an engine just like it for myself. It really came out great.

[stubble88]

Originally Posted by PeteKz

Check with Steve Wong for a new chip too. Increasing the displacement slightly wont' affect the Motronic much, but adding the twin plug heads will.

I Have. Just handed him $1k for a custom 3.2 chip. So I guess it will be another $1k if I want a 3.4. I don’t think I’m willing to do that at this point. A chipped 3.2 is just fine for now.

[mikedsilva]

Originally Posted by mepstein

Yea, we recently built a 3.2 to 3.4 twin plug, 964 distributor, big valve heads, etc. the 3.2 to 3.4 only requires the larger p&c’s. You don’t have to twin plug it to go bigger. We stick with the stock motronic but remapped a custom chip. You’re not gong to find a listed price on the internet to make the changes but parts are easy to price out and if you are doing the work yourself, then labor is “free”. If you are sending it out, then labor is whatever your builder charges, there’s no standard rate.

We rebuilt the transmission with custom gears. I think that mod tends to get overlooked when building a hot rod. It’s not cheap but makes a big difference on the overall drivability of the car.

how did you find the fitment of the Elephant Racing oil crossover pipe? I've used them on 3.0 and 3.2 and found they needed 'tweaks' in both cases...

[thetorch]

Originally Posted by mikedsilva

how did you find the fitment of the Elephant Racing oil crossover pipe? I've used them on 3.0 and 3.2 and found they needed 'tweaks' in both cases...

The issue I found with that crossover pipe is that you can't get the engine on the yoke /stand without taking that oil line off, which can be a PITA to remove and retorque with the return tubes in the way.

2 cents

[vl5150]

I built my '89 to a 3.4 in 2022, but I split the case. The Mahle P&C kit ps98-010 can be run on a single plug. The heads should get reconditioned and then you might as well have the good valve springs put in there. I had Bill at xtreme cylinder heads chamber the edge of the 95mm combustion chamber to match the new 98mm bore. The price went up fast for me when I decided I didn't want to drop the engine again anytime soon and I replaced or refurbished the rest of the engine bits. So fuel lines, sensors, clutch, and other goodies start cause scope creep when doing this job. But spending on the parts up front and doing it all at once saves you time and money in the long run so just be prepared for that when you eventually decide to do it.

[stubble88]

I’m doing the same thing.
Just found brand new Mahle ps98-010 on sale for $3400! Now waiting on heads and crank polish. The heads already have AASCO valve springs so I’m keeping those.

[Axel84]

Who got em on Sale for 3400?

[stubble88]

Originally Posted by Axel84

Who got em on Sale for 3400?

https://www.cspracing.com/mahle-ps98-010-ms-piston-cyl-set-84-89-por-911-carrera-98mm-bore-74-4mm-strk-127mm-rod-23mm-pin-35-8cc-10-1cr/dgjh-ps98-010/

[Axel84]

Thanks buddy!

[Axel84]

https://www.cspracing.com/mahle-motorsport-ps98-017-mahle-ms-84-89-porsche-911-carrera-3-4l-98mm-bore-74-4mm-stroke-127mm-rod-22mm-pin-43-2cc-11cr/dgjh-ps98-017/

would this set be better if you got access to premium fuel?
or would Twin plug be needed?


How are the pistons shaped on these sets - are 993SS and DC20 still max for lift etc..?

[911MANN]

Be careful here, Axel. 11.0:1 compression is twin-plug territory here with American 93 Octane fuel. I couldn't comment as to your 5-Star fuel safely working with this set.

One other thing is out of whack- Your Carrera connecting rods take 23mm wrist pins, not the 22mm pins noted on the website description. I suspect it's a mis-print on the website, but you need to be sure that dimension is correct for your application. Let us know what you do!

[Jeff Alton]

Originally Posted by stubble88

https://www.cspracing.com/mahle-ps98-010-ms-piston-cyl-set-84-89-por-911-carrera-98mm-bore-74-4mm-strk-127mm-rod-23mm-pin-35-8cc-10-1cr/dgjh-ps98-010/

We can do that set for the same price as well

Cheers

[Jeff Alton]

Originally Posted by Axel84

https://www.cspracing.com/mahle-motorsport-ps98-017-mahle-ms-84-89-porsche-911-carrera-3-4l-98mm-bore-74-4mm-stroke-127mm-rod-22mm-pin-43-2cc-11cr/dgjh-ps98-017/

would this set be better if you got access to premium fuel?
or would Twin plug be needed?


How are the pistons shaped on these sets - are 993SS and DC20 still max for lift etc..?

This set shows a 22mm wrist pin, not sure if that is a typo by Mahle or not as that is what their lit shows. Does not make sense mind you as they list the correct 3.2 rod length.


Cheers

[SkunkWorks]

Originally Posted by stubble88

https://www.cspracing.com/mahle-ps98-010-ms-piston-cyl-set-84-89-por-911-carrera-98mm-bore-74-4mm-strk-127mm-rod-23mm-pin-35-8cc-10-1cr/dgjh-ps98-010/

Originally Posted by Jeff Alton

We can do that set for the same price as well

Cheers

Sent you a PM. Local as well