Norm Posted 8February, 2015 Report Share Posted 8February, 2015 I'm fairly technically minded, but can someone tell me why certain competition (air cooled) 911's use PMO carbs? I thought carbs were an outdated technology many years ago..? Link to comment Share on other sites More sharing options...
Airhead Posted 8February, 2015 Report Share Posted 8February, 2015 Cause nothin sounds like an aircooled flat 6 sucking air through a unfiltered carby! Triple throat webers are scarce/expensive and carbies belong on the early 911s - not have them converted to injection. Link to comment Share on other sites More sharing options...
SM911 Posted 8February, 2015 Report Share Posted 8February, 2015 One of the Canberra crowd may be able to contact one of their brethren who is currently working at PMO in California... He should be able to answer that question! Link to comment Share on other sites More sharing options...
tk111 Posted 8February, 2015 Report Share Posted 8February, 2015 I suppose it's like asking why buy an Aircooled 911 instead of a more technically advanced Water cooled one? You could get a 996 for less than an old Aircooled these days. It would probably outperform in almost all areas except Nostalgia. (And some would argue aesthetics) Horses for courses. Link to comment Share on other sites More sharing options...
Norm Posted 8February, 2015 Author Report Share Posted 8February, 2015 I suppose it's like asking why buy an Aircooled 911 instead of a more technically advanced Water cooled one? You could get a 996 for less than an old Aircooled these days. It would probably outperform in almost all areas except Nostalgia. (And some would argue aesthetics) Horses for courses. That's a good way of putting it. Despite owning a 3.2 myself, I never thought of it that way. I wondered if you were using the car for competition, why wouldn't you fuel inject it, but then why wouldn't you gets newer technology. It's an obvious answer! Link to comment Share on other sites More sharing options...
michel Posted 8February, 2015 Report Share Posted 8February, 2015 http://www.pmocarb.com/testimonials.htm Link to comment Share on other sites More sharing options...
Norm Posted 9February, 2015 Author Report Share Posted 9February, 2015 Wow! Interesting reading. After that many testimonials, I believe them! I have read somewhere, sometime back that carbs can give better throttle response. I kind of dismissed it at the time, but now believe it. Link to comment Share on other sites More sharing options...
DS911 Posted 9February, 2015 Report Share Posted 9February, 2015 I put PMO 46's on my 3.2SS. I don't drive the car too often so starting is sometimes a challenge but no more than 3 goes normally gets it going. Early on I thought that maybe EFI was a better option but when I did the motor I really wanted carbs, plus they are a cheaper option than ITB EFI. I have noticed that when I use the car more often (say every 3-4 days) it starts easily. After the motor had it's initial 'running in' I took it down to be dyno'd (Melbourne Performance Centre - highly recommend these guys). I asked the tuner there if he thought that EFI would be much better. He said that it will help cold starts, cold idle and will smooth out the power curve. With carbs you inevitably compromise somewhere along the curve. He did say that I wouldn't extract more power, just that the car would be a bit more driveable for street use. I guess if racers are favouring carbs or EFI it may be because of the cost v benefit. They are obviously not that worried about idle and low RPM performance - they can tune the carbs specifically for their purpose. With this logic using carbs seems like an obvious choice. Having said all that now that the car had been properly tuned it is such a good motor. It's smooth, has great torque from early in the rev range and of course sounds sensational. I would buy PMO's again without a doubt. Maybe if I had a bigger budget I would seriously consider ITB EFI but no complaints with PMO. Link to comment Share on other sites More sharing options...
9er Posted 10February, 2015 Report Share Posted 10February, 2015 PMOs definitely improve on the idle circuit of Webers and certainly offer a superior throttle shaft. However when set up correctly even 30 year old Webers are a beautiful thing on an air cooled Porsche. I don't feel that I am missing out on much vs F.I., but my emission count is probably something to be ashamed of. I will be using Webers on my next projects also, I've stripped my current set down a few times now (because of owner error) and you come to love them. Link to comment Share on other sites More sharing options...
Simonoz Posted 10February, 2015 Report Share Posted 10February, 2015 I'm fairly technically minded, but can someone tell me why certain competition (air cooled) 911's use PMO carbs? I thought carbs were an outdated technology many years ago..? Norm We have to use carbys under the historic and targa rules. No choice given. Webers have become too difficult to repair, and life becomes easier with PMO's as they are new and once set up, run well without servicing. I would love to get away from carbys but cant if the car has to stay compliant. PMO's are very good, but they are still carbys with a lack of precision over EFI. Mind you, at 7,000 rpm with an open exhaust, they add to the mix somewhat. Link to comment Share on other sites More sharing options...
JV911 Posted 11February, 2015 Report Share Posted 11February, 2015 I'm fairly technically minded, but can someone tell me why certain competition (air cooled) 911's use PMO carbs? I thought carbs were an outdated technology many years ago..? - ze rules probably stipulate that you can't run EFI - good bang for your buck compared to EFI ITBs Link to comment Share on other sites More sharing options...
clutch-monkey Posted 15March, 2015 Report Share Posted 15March, 2015 I'm fairly technically minded, but can someone tell me why certain competition (air cooled) 911's use PMO carbs? I thought carbs were an outdated technology many years ago..? peak power on a proper carb setup is the same or extremely close to the peak power on an EFI setup on the same engine. and a step up over early attempts at EFI intake manifolds and injection, with much better throttle response (essentially have ITB's). However EFI wins everywhere else - lower range power, driveability around town when not at WOT, economy, emissions, cold start.. i.e. everything irrelevant to a competition car. to have the best of both worlds you need to go ITB's paired with a good EFI system and tune which is more expensive again- hence carbs still popular. Link to comment Share on other sites More sharing options...
Norm Posted 16March, 2015 Author Report Share Posted 16March, 2015 Thanks for the info and response Link to comment Share on other sites More sharing options...
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