Simplify your intake system: one 4 barrel! - Page 3

Oh Haha · 03-15-2009, 06:41 AM

Check this out:
Porsche 911 GT5S PCA Race Car

I only know thae car from Gingerman but I bet the owner could shed some light on how the Holley carb works.

EarlyPorsche · 03-16-2009, 08:24 AM

Reasons why a CHOKE is needed is for the times you have all mentioned. No pumping to fiddling or first, second, third catching the engine to fire. You just get in, squeeze the gas to the floor to set the choke and turn the key. Then it will evenly warm up the engine and allow you to drive easily without popping and spitting. There is no good reason to leave a choke off a daily driven car. Nobody needs that extra couple hp that MIGHT be lost from the air turbulence when it is wide open. It probably really doesn't lose any hp.

Formerly Steve Wilkinson · 03-16-2009, 08:44 AM

I have absolutely no problem with "popping and spitting" when cold with chokeless PMO carburetors. They work just fine when the car is cold (i.e. down to 30 degrees F. or so, since I don't drive it in the depths of winter). The car _can_ be started on the first attempt when cold if you know what you're doing and will drive off perfectly normally after about 30 seconds. I have no need for chokes. Accelerator pumps work just fine.

EarlyPorsche · 03-16-2009, 09:52 AM

I agree that it can be done and its fine, however mine pops for a couple minutes until warm in colder weather. It might just be my carburetors but I don't think so. An accelerator pump is varying fuel not air. The reason chokes work so well is that they restrict air while increasing fuel instead of the way webers increase fuel with a fixed amount of air. If you drive a carburetor car with a choke you will see how much smoother it is. No matter how smooth your webers are a choke makes it better. Now I don't disagree that some may not want it, but I personally think a street car should come with it and then race carburetors should have them removed.

RWebb · RWebb's Garage

you guys are getting way off topic

but.. a sports car should be as difficult to drive & live with as is humanly possible -- like the G50 transmission, a choke detracts from that overarching Goal

911pcars · 03-17-2009, 12:57 PM

Quote:

Originally Posted by EarlyPorsche

I agree that it can be done and its fine, however mine pops for a couple minutes until warm in colder weather. It might just be my carburetors but I don't think so. An accelerator pump is varying fuel not air. The reason chokes work so well is that they restrict air while increasing fuel instead of the way webers increase fuel with a fixed amount of air. If you drive a carburetor car with a choke you will see how much smoother it is. No matter how smooth your webers are a choke makes it better. Now I don't disagree that some may not want it, but I personally think a street car should come with it and then race carburetors should have them removed.

Think of the complexity and cost/benefit of controlling 6 chokes and associated linkage. Plus, there's that choke plate and shaft hanging in the induction path. Good idea for a Ford; bad idea for a Porsche. I believe carbureted 911s have started and run without complaint for about 40+ years thus far.

Sherwood