Carb conversion for 944

[1QuickS]

I know this is silly but I would like to know what info there is regarding installation of a pair of side drafts onto my '88 944S. In the 911 world, CIS systems are dumped for Webers with the following results: simplicity in the engine bay, lower fuel mileage, no power improvement and improved throttle response.

This would be for a car living in a smog exempt region.

I assume the ignition would need to be revised since CIS & ignition are intertwined.

I also assume the compression ratio would be too high for pump gas since removal of CIS would also remove the knock sensor.

Perhaps the cams would need revision to provide some overlap to help draw fuel into the combustion chamber.

Just asking.

[DannoXYZ]

The Motronic in 944 is light-years ahead of CIS and carbs. You will definitely lose power and responsiveness in going to any kind of carb. For example, starting the car on a 50-F day on the 1st crank and driving smoothly off after 5-sec warm-up. Or starting up after a 20-min track session on 100-F day.

[Jrboulder]

Yup, 944s just aren't your cup of tea.

[1QuickS]

Yup, 944s just aren't your cup of tea.

I'm beginning to have that reality sink in.

[Jrboulder]

There are some distinct positives to 944s:
Low entry price
Stable, predictable handling
Practical configuration
Decent MPG
Decent out of the box performance/handling
Good daily driver
Approaching modern EFI

If you're looking for something like a hot early 911 you really won't find what you're looking for:
Even with drastic measures you won't get close to the stock weight of an early 911.
There are some areas where you can mod it to be what you want and there are some areas where it's really not worth it.
Until you get into turbos, the engines are pretty set in their ways with only minor mods being able to be done.

[1QuickS]

Yeah, I see little engine work to be done for N/A engines & I definitely do not want a Turbo...too dangerous of becoming a "collector car". I like all the positives about 944s but am dismayed by their lackluster performance. However, it is not all bad for me to slow down a bit & use it as a "GT"; it is just that I didn't expect to slow down THAT MUCH.

Thanks!

[Jrboulder]

Originally Posted by 1QuickS

Yeah, I see little engine work to be done for N/A engines & I definitely do not want a Turbo...too dangerous of becoming a "collector car". I like all the positives about 944s but am dismayed by their lackluster performance. However, it is not all bad for me to slow down a bit & use it as a "GT"; it is just that I didn't expect to slow down THAT MUCH.

Thanks!

You need some seat time in my 912E. Then you'll appreciate your 944S a lot more lol

[jhowell371]

I guess I'm just a Neanderthal but I believe properly set up carburetors will produce just as much power as FI, after all the engine is just an air pump. My Harley will start hot or cold with the vacuum slide carburetor providing excellent throttle response. It's a perfectly serviceable unit for vaporizing fuel in the proper ratio. Yes FI is more flexible but us old timers did wonders by using the rapidly disappearing art of reading plugs and swapping jets or drilling them out and playing with float levels. This was something any shade tree racer could do and did, car or motorcycle. FI was as much for tightening emissions as for performance gains. My 63 Corvair Spyder Turbo had a mechanical vacuum advancing and boost retarding distributor, no chips needed. It used a single barrel side draft carburetor bolted to the Turbo.

[1QuickS]

I'm a carb specialist for the 911 world & user of same. Webers are magical! I had a 1979 911SC and my 1967 911S with 2.0 engine. I kept the 67S (when I made a move 30 years ago) since it was much more alive than the SC. But, to take a long trip, it was the SC with its cruise control, air conditioning & stereo.

Webers on an SC do produce same HP as CIS but deliver lower mileage. Throttle response with Webers make you think you gained 20HP over CIS.

[dgcantrell]

Carb-ing and EFI engine is an exercise in futility in my book. The cam is not ground for carbs at all. Lot of people rip the EFI off of 914 engines, leaving the EFI cam in it and wonder why it runs like crap. Usually all that was wrong with the EFI was a simple vacuum or intake/throttle body coupling leak.

[sausagehacker]

Why not go forward instead of backward? Install a modern ECU and remove all the primitive EFI parts. You can pick up power without even trying just by removing the AFM and tuning the car for maximum power on whatever fuel you want to run. It would be less work as well, there are even PnP kits out there.

[flash968]

WOT is one thing, and carbs can be made to produce equivalent power there. the issue is everywhere else. carbs do not have the same tuning capabilities, nor the same efficiencies. you have to run them very rich to get the power, and then you are washing your cylinders. cleaning that up, and achieving stoich is why engines no longer wear out at 80-100k.

you can get the same or better throttle response with FI. you just have to tune for it. that is very easy to do with an ECU. not so easy with jets, springs and offset keys.

i used to do it old school, and mess with that stuff, back when i was running the MGB (30 years ago). went like a raped ape, as long as i had my foot in it. ran like crap the rest of the time. if i were to do it again, and i have been thinking about it, i would absolutely go FI and ECU

besides, who cares about WOT?

[thomasryan]

Lol..at 6000', WOT is all I have.

Look at the specs for CIS cams. Vacuum is key. IMHO, CIS + turbo is a match made in analog heaven.

Chewbacca has a good thread on a standalone running a blended mode megasquirt2 using throttle bodies 944 Forum - Blended ITB mode, Porsche 924 Megasquirt 2

[flash968]

lol - that's exactly why i designed the supercharger kit for the 968. at a bit over 3k lbs, that car was way too big and heavy for the mere 240hp that comes stock.

[Rasta Monsta]

Sounds like you need a 931.

[v2rocket_aka944]

The main problem with the 944S is the AFM and the DME tune.
The 944S DME is "emissions uber alles".

Get a DME chip, or a plug-and-play aftermarket ECU ($1000 or so) and it will really wake up. Moreso if you can ditch the flapper-door AFM (replaced with a MAF or MAP sensor).

You won't believe the transformation...and it will be cheaper/easier/nicer to drive than a Carb setup.

[1QuickS]

The main problem with the 944S is the AFM and the DME tune.The 944S DME is "emissions uber alles".

Get a DME chip, or a plug-and-play aftermarket ECU ($1000 or so) and it will really wake up. Moreso if you can ditch the flapper-door AFM (replaced with a MAF or MAP sensor).

You won't believe the transformation...and it will be cheaper/easier/nicer to drive than a Carb setup.

Thanks! This is what I was looking to hear about.

[v2rocket_aka944]

Megasquirt DIY kit if you are electronically handy, build it yourself for $430:
https://www.diyautotune.com/product/diypnp-bosch-55pin-unassembled-kit/

Or there is VEMS plug-and-play for about $1200 including a tune to start and run the car. Literally, unplug your old DME and plug VEMS into the 944 engine harness. Run one or two more sensors under the hood, and go.

Both Megasquirt and VEMS are extremely capable aftermarket ECU's that run MAP sensors so there is nothing installed in the actual intake plumbing, just a vacuum hose to a separate sensor...I have VEMS on my car, sausagehacker has the MS.

[bumflick]

Or you could just go LSx...

[1QuickS]

Or you could just go LSx...

or Nissan VQ35HR

Jenvey ITB Install : OnPoint Dyno