1986 twin plugged intake
 

I rebuilt my '86 Carrera engine 10+ yrs ago and I am ready for the next evolution and looking for ideas and experience out there.

When rebuilt I increased the pistons to give me a 3.5L engine and twin plugged it. Stock motronic EMS with a chip tuned from 911chips. It is running with a stock intake right now and makes decent power but I know the restriction is in the MAF door area and intake runner design. Essentially choking airflow.

Now short of putting ITB'S and ripping out all EMS parts and starting from a scratch program then dyno tuning, here is my question...

Is there a custom, or maybe stock 964 solution, that will let this thing breath better than my granny crossing the living room? I'd rather just throw another chip in the stock Motronic EMS after bolt on parts and a dyno session.

Thoughts? I fear I may need to go to a fully programmable modern EMS to squeeze water from this rock and I fear the juice just isn't worth the squeeze.

Thanks in advance.

Thoughts and suggestions welcome

Subscribed! Hope you get some good responses.




(Just finishing up a 3.2 to 3.4 build)
Erik

Obviously ITB's are the ultimate but below that
964 uses the same type of barn door as 3.2, 993 goes one better w/ hotwire mass air flow measurement

plastic 964/993 resonance manifold w/ ITBs is a step up from plain ITBs's, or use the similar aluminum GT3 resonance manifold w/ ITB's

w/ any of these the electronics to run them are critical, most likely you would want Motec or similar though Steve W does wonders w/ Motronic

993 Cup did use the plastic resonance manifold w/o hotwire or barn door, they used MAP sensors w/ 55 pin Motronic

Thanks for the input Bill. Steve did my heads and case machining. Maybe I'll ping him.

It was sad to find out Steve Weiner has passed away. Such a giving and resource Porsche man will truly be missed.

Is there anyone out there that has the kind of experience he had that could give me some guidance on this project?

Steve W in this case refers to Steve Wong, from 911chips.com as you used him previously? He is still around and indeed very experienced with air cooled 911s especially the Motronic ones.

Adapt Motorsport makes a very nice billet aluminum kit to bolt on the bigger plastic/alu 964 intake to the 3.2 and smaller engines, not cheap however.

Sam Carceller makes a MAF kit that is very highly regarded, and is the closest you will get to a plug and play solution:


"Attached is Brochure for my MAF.
It's a complete system not just a MAF conversion, comes with:

- Custom DME to run the MAF, no core required, you keep your existing DME
- 6 new modern day Bosch OEM 4 hole 34lb injectors
- The MAF assembly complete with Air Cleaner and wire harness

100% plug and play, no extra wiring or modification of wiring required, just unplug the old components and plug in the new.

You MUST install a decent WideBandO2 gauge, we will need it to properly calibrate the MAF after installation.

The MAF can be used with displacement upgrades without any issue, 3.4L or 3.5L as well as stock 3.2L

Cost is $3000 USD

It's not required to enlarge the throttle body on a 3.2L setup, won't buy you much. But on a 3.4L or 3.5L upgraded engine it does make sense."

I have a plastic 964 intake I could sell. I will take pics if you're interested.

Thanks but I'm good.

Thanks for the input. It is seemingly not worth the money from everything I read.

Here's a thread showing my MAF and twin plug solution results in a similar engine to what the OP has here.

https://forums.pelicanparts.com/porsche-911-technical-forum/1077817-84-89-3-2l-upgraded-3-5l-267-wheel-hp.html

This is a track use DE dedicated car that can easily be street driveable.

I'm curious what WHP the engine in this post made? Was any dyno session performed? You should expect to get 260-270WHP from a build like this.

The big restriction in the intake is the AFM then the Throttle Body, the air cleaner housing and the intake runners are not an issue. I know this because we have monitored intake vacuum levels very carefully during WOT dyno pulls at hi-rpm range. The single biggest improvement was removing the AFM followed by TB enlargement, those 2 things allowed us to get intake vacuum down to 0 to -0.5PSI with stock AFM and TB we had been >-2.0PSI!

Sal's stuff works incredibly well
I've used several and the power and drivability are remarkable

I got 278HP at the crank on the dyno.

I've driven a 3.4 twin plug with Sals MAF system. Fantastic smooth power.

That's great result, nice job on the build and the WOT tune.

Sal,
Curious how you established the "intake runners are not an issue"?

TIA!

The quoted paragraph explains it.