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 Posted: Jan 10, 2018 02:04PM
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I have never seen anything that proves these things actually do any good at all, seen lot's of claims but no proof. Anybody got any dyno figures or any other form of proof that they do more good than harm?

Mini's are like buses they come along in a bunch

 Posted: Jan 10, 2018 01:24PM
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liquid fuel does not burn

fuel must be volatilized (turned gaseous) in order to burn

fuel is best volatilized with warm or hot air (up to a point, before other issues arise)

but, cold air is denser, hence more O2 available for combustion per unit volume (speaking normally aspirated here)

generically speaking, what we need here is balance in these two factors.

This does not help you much, but in simplist terms, there it is.

 

 Posted: Jan 10, 2018 07:10AM
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CA
Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Dan Moffet

...If it were effective, you'd see them on racers.
I'm familiar with water heated intake manifolds and I've heard of dashpot heaters. I just assumed they were used only in extremely cold climates. But icing under normal conditions? "Joltfreak" was getting icing with a simple bonnet scoop. Who would have thought? When it comes to carburetors, the SU is an interesting beast. Thanks for the detailed explanation. That we don't see the racers use CA systems is the final proof statement.
Carb icing can occur on hot days (e.g. 75-80 F) with high humidity.
Another interesting artifact: VW air-cooled engines had an exhaust cross-over tube to warm the intake manifold. Without it they would ice up on hot, humid days, choking and stalling.

Conversely I had a 1975 FIAT X1/9 which had a transverse mid-engine layout. There was about the same air space around the lump as in a Mini but with the mid-engine arrangement there wasn't much air flow around it, even with a vented engine compartment hood. It was fine running and I never had a problem (2-barrel downdraft carb). The unusual thing was that the carb was fitted with an air duct, not to the intake but to the bowl. When you shut the engine off, a fan would continue to blow ducted air around the bowl until a thermostatically-controlled switch would decide the carb was cool enough to prevent fuel vapour lock. Walking away from the car, it sounded like the heater fan was left running.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Jan 10, 2018 12:25AM
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I remember when i first installed a cold air intake on my classic mini, Larry lebel (Aka Cupcake) was the first person here to contradict the idea, he said that the air that come inside the intake should be warm not cold.Thus air intakes were situated beside the engine to make the air warm before it gets inside the intake.
after he said that he deleted his account and i believe he re-joined this group using a different username but he doesnt tell anyone it was him. Aanyway!

 Posted: Jan 9, 2018 09:02PM
mur
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There are excellent resources on the internet that can teach you about how and why carb icing occurs.

 Posted: Jan 9, 2018 08:10PM
 Edited:  Jan 10, 2018 02:26PM
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US
When the Mini was designed, the engine was turned the other way on the gearbox; i.e., the carb and exhaust were at the front. It was rotated 180 degrees on purpose to get the carb to a warmer place.

 Posted: Jan 9, 2018 07:17PM
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US
Quote:
Originally Posted by Dan Moffet

...If it were effective, you'd see them on racers.
I'm familiar with water heated intake manifolds and I've heard of dashpot heaters. I just assumed they were used only in extremely cold climates. But icing under normal conditions? "Joltfreak" was getting icing with a simple bonnet scoop. Who would have thought? When it comes to carburetors, the SU is an interesting beast. Thanks for the detailed explanation. That we don't see the racers use CA systems is the final proof statement.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Jan 9, 2018 11:20AM
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Member since:Oct 9, 2003
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CA
On my a series equipped mini, I had a functioning “ram air” scoop in my bonnet and I started to have fuel icing issues in the early spring and late fall. I had to plum the coolant the intake to resolve this (I put a valve to allow me to bypass the intake if needed during the summer months as well).

check out the official website for updates!!!!!  //www.minimeetnorth.com

 

 Posted: Jan 9, 2018 06:16AM
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CA
Minis were conceived and born into a cool, damp climate. Inside the intake throat, after the throttle, air pressure drops dramatically (except maybe with the throttle wide open. Humid air will condense and even freeze to the inside of the intake manifold, to the point of choking the car. Originally the intake and exhaust manifolds were Siamesed to provide heat to the intake to prevent icing. Most aftermarket alloy intake manifolds provide a water passage for heating using the heater hose circuit. In early Minis, during cold weather, the air filter housing would be rotated so that the intake horn would be directly over the #4 cylinder exhaust port elbow, to scavenge some warm-ish air. During warm weather, it would be swung away towards the firewall.

In colder climates, e.g. Canada, an electric heater was factory-installed between the carb and the cast iron Siamesed manifold, to provide additional warmth for fuel evaporation until the manifold warmed up. They also came with a dashpot heater.

Generally, when the car is moving, there is pretty good air circulation around and behind a Mini motor. Heat becomes an issue when it isn't moving and/or when a huge exhaust header is on a tricked out motor. Modern car engine bays are so tightly packed, air barely flows, and the engines produce a lot more heat.

Another issue to consider is intake resistance of a long passage. If it were effective, you'd see them on racers.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Jan 8, 2018 09:15PM
 Edited:  Jan 8, 2018 10:59PM
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US
I've wondered why so little attention is given to cold air intake systems for our classic Minis. Virtually every new car manufacturer provides a cold air solution and there's tons of aftermarket CA kits for almost every application.

Our SUs couldn't be in a worse location; at the rear of the engine bay and directly over the headers for crying out loud. My headers have a ceramic coating and there's a stainless steel heat shield between the headers and the carbs, but still, the SUs are sucking air from what has to be the hottest spot under the bonnet. I've seen CA systems on turboed and supercharged Minis that require a lot of extra intake plumbing anyhow, but not much is said about feeding cooler air to our conventionally aspirated motors. Has anyone put together a CA system for their SUs?

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports