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The pros and cons of going carbuerated?
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Stampedetrail  



Joined: 29 May 2005
Posts: 274
Location: Fairbanks, Alaska

PostPosted: Wed May 17, 2006 1:41 pm    Post subject: The pros and cons of going carbuerated? Reply with quote

Some of you no doubt have switched to carbueration as opposed to the stock fuel injection. Is this wise? Is there a benefit in power? The simplicity and reliability of carbueration in obvious, but how can you get as precise a fuel/air mixture with this configuration? Or am I all wrong? & what about fuel economy? Just a thought.
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1977.5 924 "Martini" head / New Old Stock rebuild
1985.5 944 Why? Because I can.
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Lizard  



Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada

PostPosted: Wed May 17, 2006 2:11 pm    Post subject: Reply with quote

I wouldnt call carbs really reliable personally,

as per fuel economy, it will go straight downhill.

as per power, abit over stock not much though.

a better solution is to convert to EFi
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Khal  



Joined: 26 Sep 2003
Posts: 4864
Location: Sunny and lovely interior BC, Canada

PostPosted: Wed May 17, 2006 4:10 pm    Post subject: Reply with quote

I think Vince has gone to carb's at least once before. I pretty sure Applebit did, too. Maybe others..?

Can't imagine why you'd do it unless you're looking to do some sort of performance modification that requires carb's or works particularly well with them.

Otherwise I'd be inclined to see it as whole lot of unnecessary expense and hassle.

There's a good reason why nearly every modern car on the planet went to fuel injection and, in particular, electronic fuel injection... 'cause carb's are sh*t and fuel injection is good!
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Llamaguy  



Joined: 02 Jul 2003
Posts: 711
Location: Indiana

PostPosted: Wed May 17, 2006 8:10 pm    Post subject: Reply with quote

I think there were a couple who used some weird, expensive, side-draft carbs that might get you some where on a '77, but it wouldn't be worth it to lose all the reliabilty of FI or EFI
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Peter_in_AU  



Joined: 29 Jul 2001
Posts: 2738
Location: Sydney, Australia

PostPosted: Wed May 17, 2006 8:30 pm    Post subject: Reply with quote

If you love the smell of stale petrol everytime you get into the car or you only drive the car at wide-open-throttle then carbs are for you.

If you use the car on the road forget them. If you want to upgrade then go EFI. Carbs belong on `56 Chevys.
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timstar92404  



Joined: 22 Sep 2004
Posts: 2075
Location: richmond BC

PostPosted: Wed May 17, 2006 10:52 pm    Post subject: Reply with quote

the only pro I can think of is that they look cool and the engine area looks much cleaner with all the CIS removed.
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Vince Ponz  



Joined: 03 Nov 2002
Posts: 3581
Location: Florida

PostPosted: Wed May 17, 2006 11:32 pm    Post subject: Reply with quote

If you have the money and time I would say go for it if it will be a track car. No, you will not be superfast but occasionally you will stay with an early 911 etc.

I have had them on with a cam and free exhasut for over 23 years. I since added 44 suspension, bars, euro pistons etc.

The 5 speed helped as I had a four speed in it which was also changed out a long time ago. Gas was hurt but not by much. HP maybe 135-140 but not much more. As a hobby it is fine. Be prepared to put in some serious money to do this. That said buy a 944 turbo.

Like the 924?............. then leave it stock if you cannot pay for it or you will sell it when you find out that it still is not fast enough. These cars are relics. Sell them if you do not love them. For those on this board you know what I mean. They come and go like flies. Mr. Timstar are those wings I see.

Really I don't want to bash anyone but be happy with what you have. I never boast about my other cars as you can see I do own a garage queen in the 87 Targa.

Sold the 924S. It will go racing next year in the 944/924S series.
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Vince Ponz  



Joined: 03 Nov 2002
Posts: 3581
Location: Florida

PostPosted: Wed May 17, 2006 11:34 pm    Post subject: Reply with quote

If you have the money and time I would say go for it if it will be a track car. No, you will not be superfast but occasionally you will stay with an early 911 etc.

I have had them on with a cam and free exhasut for over 23 years. I since added 44 suspension, bars, euro pistons etc.

The 5 speed helped as I had a four speed in it which was also changed out a long time ago. Gas was hurt but not by much. HP maybe 135-140 but not much more. As a hobby it is fine. Be prepared to put in some serious money to do this. That said buy a 944 turbo.

Like the 924?............. then leave it stock if you cannot pay for it or you will sell it when you find out that it still is not fast enough. These cars are relics. Sell them if you do not love them. For those on this board you know what I mean. They come and go like flies. Mr. Timstar are those wings I see.

Really I don't want to bash anyone but be happy with what you have. I never boast about my other cars as you can see I do own a garage queen in the 87 Targa.

Sold the 924S. It will go racing next year in the 944/924S series.
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77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock
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Vince Ponz  



Joined: 03 Nov 2002
Posts: 3581
Location: Florida

PostPosted: Wed May 17, 2006 11:36 pm    Post subject: Reply with quote

If you have the money and time I would say go for it if it will be a track car. No, you will not be superfast but occasionally you will stay with an early 911 etc.

I have had them on with a cam and free exhasut for over 23 years. I since added 44 suspension, bars, euro pistons etc.

The 5 speed helped as I had a four speed in it which was also changed out a long time ago. Gas was hurt but not by much. HP maybe 135-140 but not much more. As a hobby it is fine. Be prepared to put in some serious money to do this. That said buy a 944 turbo.

Like the 924?............. then leave it stock if you cannot pay for it or you will sell it when you find out that it still is not fast enough. These cars are relics. Sell them if you do not love them. For those on this board you know what I mean. They come and go like flies. Mr. Timstar are those wings I see.

Really I don't want to bash anyone but be happy with what you have. I never boast about my other cars as you can see I do own a garage queen in the 87 Targa.

Sold the 924S. It will go racing next year in the 944/924S series.
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77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock
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John Brown  



Joined: 07 Nov 2002
Posts: 903
Location: Leesburg VA

PostPosted: Wed May 17, 2006 11:54 pm    Post subject: Reply with quote

We had MSDS headers, straight pipe to the rear, and an Inegral Cam. Added Mikuni carbs. Not really a big change.

Once again, the 924 motor demonstrates that Porsche did an excellent job making it go just fast enough to not be easily modified to keep up with the then current low end 911. The head layout is the problem. Turns out if you want to spend that amount of time and money you copy the DP engines and stick a 931 head on with appropriate pistons.

In short, the next 924 motor I want to make run fast I'm going to do other things first before messing with carbs.
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Paul  



Joined: 02 Nov 2002
Posts: 9414
Location: Southeast Wisconsin

PostPosted: Thu May 18, 2006 10:38 am    Post subject: Reply with quote

Most carbs are more complicated than CIS and much harder to tune!

I can't tell you how many hours I've spent of my life trying to tune Webers and Mikunis....
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sequential  



Joined: 18 Nov 2005
Posts: 500
Location: BANNED

PostPosted: Thu May 18, 2006 12:56 pm    Post subject: Reply with quote

I must say it is impossible not to pickup HP by going to multi -side draft carbs cams and exhaust. over cis . i Do believe it is possible with mikunis
not to pick up HP. Has to be the worst High performance carbs ever.
In the past i have used mik, webers , dellorto , holley on vw ,audi and porsche motors and find the weber to be the best at hp and the dellorto TO offer the best overall performance. we have always lost power going to mikuni carbs so had binned them a long time ago.
If you use weber carbs you will need dyno tme to correctly jet the thing .
STAY AWAY FROM MIKUNI'S.................

the 924 engine will respond best to CR increase , this is a must with any mods.
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Stampedetrail  



Joined: 29 May 2005
Posts: 274
Location: Fairbanks, Alaska

PostPosted: Thu May 18, 2006 6:35 pm    Post subject: Reply with quote

Actually, 140 HP is pretty good considering the engine size. CR will go up, eventually, which is something I did when I rebuilt the motor of my 1972 Toronado (decommissioned battleship). When it is rebuilt I'd like to pick up a few ponies but dont want to lose a lot of positive features for little gain. At the moment, the carb is looking pretty good, as a nice-looking DELLORTO DRLA 36 sits on Ebay for $275-400--- fuel injectors are about $200, plus you have to worry about the electric pump going out, futzing with the fuel distributor maybe, etc. And no way in hell am I buying a 944 haha.
EFI sounds interesting but how do you go about it? Rip it out of an existing modern car & do a ton of welding on it or what's the deal with it, just out of curiosity?
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stexch  



Joined: 05 Dec 2003
Posts: 90
Location: Mankato, KS, USA

PostPosted: Tue May 23, 2006 7:02 am    Post subject: Reply with quote

Don't try to salvage an electronic fuel injection system from another car and install it. Instead, buy a Megasquirt kit. Hire someone to install it that can give references. Get a written estimate in advance.
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Stampedetrail  



Joined: 29 May 2005
Posts: 274
Location: Fairbanks, Alaska

PostPosted: Tue May 23, 2006 6:28 pm    Post subject: Reply with quote

stexch wrote:
Don't try to salvage an electronic fuel injection system from another car and install it.

That sounds quite interesting, though. The fuel injection on the 924 is antiquated primarily because of the injectors themselves. Why couldn't somebody upgrade them? Have you seen this attempted?
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