Heat intake fuel/air mixture

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Model T Ford Forum: Forum 2010: Heat intake fuel/air mixture
Top of pagePrevious messageNext messageBottom of page Link to this message  By tyrone thomas on Sunday, December 19, 2010 - 01:54 am:

Which method would atomize the fuel/air mixture the best, heated air before the carb? After the carb? Both? Does not matter?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Halpin on Sunday, December 19, 2010 - 05:51 am:

Ol Henry provided an air pre-heat tube on the Model T to warm up the air going into the carb. That updraft carb/manifold configuration can get pretty cold an de-atomize the air/fuel mixture.
There's a lot of opinions on this (of course) but if Henry made it, there must have been a reason for it. Take a look at this picture

It's the metal thing (held on with bailing wire, because the bracket broke off) on the rear of the manifold, it goes down to the intake in the carb. Carb vacuum pulls hot air from around the exhaust manifold into the carb.
This is a 26-27 engine with a Holley NH carb on it. Other pre-heat tubes may look a little different.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Sunday, December 19, 2010 - 08:41 am:

Gasoline quality was poor in the years prior to WWII. Not only was the octane level in Model T era gas low, but the Reid Vapor Pressure (RVP) was low.

Octane rating is the ability of the gasoline to resist preignition. The compression ratio in Model T Fords was kept low because the octane level of automotive gas was estimated to be around 40 - 45 (RON+MON averaged) in the time before and immediately after World War I. Ford had compression around 4.8:1 in the 1909 - 1916 Model T. It was dropped in 1917 and again in 1926 due to the lowered quality of gasoline.

Reid Vapor Pressure is an industry standard for testing the volatility of petroleum based fuels. A lower RVP is harder to light. A higher RVP ignites easily. Crude oil has a low RVP. Gasoline a high RVP.

The heated air intakes are designed to fight problems with low vapor pressure in early gasoline. By heating the inlet air charge you can make a poorer quality fuel ignite more readily. Thus more complete burning and less carbon buildup. This was absolutely essential in 1909 - 1927 because fuel quality was absolutely terrible. Ford was willing to sacrifice a bit of horsepower to make the engine less likely to carbon up the valves and intake / exhaust passages.

Today gasoline from the cheapest independent refinery has twice the RVP of gasoline available in 1927. You will notice that your car goes slower when you install an intake heater, and faster when you remove it. You can drive many tens of thousands of miles and not have any issues with carbon buildup, provided you do not let the engine idle for long periods of time or have the mixture too rich.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Sunday, December 19, 2010 - 12:08 pm:

Royce: Wow! So you are saying the hot air pipe will make your car run slower, and there is no need to use it on a T these days?

That's a statement that makes me think you don't drive a Model T very much (or at least not for extended periods of time). Those of us that do drive many, many miles per year will know exactly what I am talking about.

If you are new to Model T's: Run a hot air pipe all the time; winter and summer. The STOCK hot air pipe, properly installed will help in cold weather and it will also prevent a certain running problem/carburetion issue from occurring on humid days in the warmer months.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Sunday, December 19, 2010 - 12:27 pm:

Adam,

I drive a lot, and my four Model T's (soon to be five) are located in two states. I have a lot of experience driving in 115 degree temperatures in places like Tucson, Arizona and Dallas Texas. On the Rocky Mountain T tour beginning at the Stanley hotel in Estes Park and going uphill from there. Touring in Virginia at sea level on rainy fall days with the temperature anywhere from 40 - 7 degrees. Used to live in Cincinnati, where we toured in rain, snow, fog, you name it.

I've tried the pipe, quit using it for the reasons stated. From a scientific point of view, I can't justify the pipe. From my experience, it hurts performance. I've noticed zero good from the pipe in cool, cold, warm, hot, dry, wet or icy driving.

I'm just sharing what I know Adam. I am not attempting to insult you or anyone else in any way. Please try to read what I say, and not be so insulting. If you have different ideas, I bet you can tell us without making personal attacks on me or anyone else.

I've been "around" Model T's since the day I was born Adam. Here I am in 1959, unfortunately not allowed to drive.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hugh Jass on Sunday, December 19, 2010 - 12:28 pm:

Actually, many of the old timers used a mixture of modified bitumen roofing tar and gasoline to combat drivability issues. The use of the carb heater was considered a requirement for proper operation


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thunder on the Plains of Colorado on Sunday, December 19, 2010 - 12:38 pm:

Is that, by chance, Robert MacNamera in that pic?

I gotta side with Royce on this one. Although I have no running Model T to test the theory, it make perfect sense from an automotive performance point of view.

Fuel performace, has been greatly improved since the early 1900. A simple test would be to mix a bit of kerosene & gas. Set that next to pure gasoline, and see which one evaporates first.

Vehicles are now built with outside air induction systems. Modern Diesel trucks have intake coolers now also. Both these systems produce a denser air/fuel mixture, thus more power. By intoducing heat, efficiency is greatly reduced, just ask a helicopter pilot.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, December 19, 2010 - 12:42 pm:

Just about everybody who has flown a light airplane will agree with Royce on this one - at least regarding performance.

I've never run a hot air pipe, either, and I've driven in all kinds of conditions, like 4,000 miles in two weeks coast-coast, and did that three times.

A word of caution: if you don't run a hot air pipe, you need an air filter, or at least a screen over the intake to break up backfirees so they don't start engine fires.

Of course, I've always run a thermostat and waterpump, too, and never any carbon or plug fouling.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Christopher Lang - Brentwood Bay BC on Sunday, December 19, 2010 - 12:45 pm:

Here near the Pacific, the carb/mainfold tends to ice up, as it drops below the dew point, and below freezing.
Not just on my T either. My daily driver is a 1950 Chev, it freezes up just after starting. In fact, I switched to an offy dual carb intake, as I foolishly thought that would help, now I just have two frozen carbs! After the truck warms up though, its fine and happy.

I think it really depends not just on where you live, but the humidity, and temperature, and dew point of the day you are driving! I suspect that everybody's experience will vary!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Sunday, December 19, 2010 - 12:53 pm:

The dark headed guy standing next to Dad's 25 pickup is Chuck Beard, president of Branniff Airways. The picture was taken at an employee picnic in the summer of 1959 near MSP airport.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris Big Bear Lake, California on Sunday, December 19, 2010 - 12:56 pm:

Air looses 70 degrees f when it goes through a carburetor. So warm wet air at 100 degrees in the summer makes ice. Hot air in colder weather assists evaporation and vaporization because our modern gasoline only vaporizes about two or three percent of the mixture until the temperature rises. The hot air tube does not assist in starting but it does assisng during the warming up period. Royce is correct about cold weather not requiring a hot air tube for efficiency, but it does assist in a faster warm up.

Hugh Jass is also correct about the hot air tube being required to liquify the B.T.R. Note that these units were mostly used in Southern California in the winter before smudge pots were invented to save the tender fruit from freezing. The smoke emitted from the hot air intake pipe fitted Model T's running B.T.R. driving up and down the rows of orange trees saved many a crop.


picture


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Von Nordheim on Sunday, December 19, 2010 - 12:56 pm:

I also agree with Royce on this issue.

Adam, You were crude in your response to Royce.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, CO on Sunday, December 19, 2010 - 12:59 pm:

Tyrome: I drive daily into town and know a lot of Ts in Colorado. I have been in 5 Model T Clubs in Colorado. I have never seen one with a hot air intake installed. Some of the best Model T mechanics in the world run the Montana 500 Race. I have never seen a hot air pipe on any racer's T. Each motor is inspected before the race and the three first place winners have their motor torn down after the race, again I have never seen one with a hot air pipe.
I think that hot air pipes is like arguing over which oil is better. Some use them some don't I don't.
A110


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Sunday, December 19, 2010 - 01:03 pm:

Les:

Adam's crude post ????

No way ! He was just stating factual experience.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thunder on the Plains of Colorado on Sunday, December 19, 2010 - 01:03 pm:

"The dark headed guy standing next to Dad's 25 pickup is Chuck Beard, president of Branniff Airways."

Thanks Royce. The resemblance is striking though.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, December 19, 2010 - 01:28 pm:

C. Lang, doesn't your '50 Chev have a heat riser on the manifold?

Again, from wiki:

"Heat Riser"....now obsolete, earlier manifolds ...with 'wet runners' for carbureted engines...used exhaust gas diversion through the intake manifold to provide vaporizing heat. The amount of exhaust gas flow diversion was controlled by a heat riser valve in the exhaust manifold, and employed a bi-metallic spring which changed tension according to the heat in the manifold. Today's fuel injected engines do not require such devices.

Heat risers routinely stick open or closed after a number of miles/years.



Note the lack of a heat pipe. It had a remotely mounted aircleaner.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Sunday, December 19, 2010 - 01:31 pm:

Would Henry have wasted proably 2 or 3 cents to manufacture and install them if they were not needed?? Maby the reason 100 years ago is lost to us now?? Hey,If anyone has a reason to be grumpy,it's me!! I don't mind the cold but its the ice,snow,and salt i hate and i dont know when any of our old cars will be out. Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace on Sunday, December 19, 2010 - 01:38 pm:

More warm air on the subject....

I have always run the hot air pipe....only once without, on the '27 Touring, summer time hot FL humid/sweaty 90 percent day...the intake at the lower bend got frost on the outside, no telling how much frost inside...car ran OK but not great.

Installed the hot air pipe, intake warmed up, T ran the best...IMO, experience with my T's, the hot air pipe is needed year round.



Installed, plus you get the sound benefit of hearing the intake "hoosh" when choke starting :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Christopher Lang - Brentwood Bay BC on Sunday, December 19, 2010 - 01:42 pm:

Yes, the stock manifold does have a heat riser (it does function), and I will post a photo of my engine about 2 minutes after starting. After it quits, I just let it sit for 5 minutes, and the heat from the exhaust manifold warms the carb enough. The heat riser valve works to eliminate fuel droplets in the intake manifold, but doesn't keep the carb from freezing, as it has a bakelite insulator under it.

With the Offy intake, dual carb, Fenton headers set up that's on the truck now, I still have exhaust heat for the intake manifold, and two frozen carbs! I now have a block heater, which warms the block, and by proxy, in intake manifold before starting. Such is life in the fog. Darn Frozen Carb


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Sunday, December 19, 2010 - 01:46 pm:

Bud,

The reason Ford used a heated air intake was stated in my first post above. In a nutshell, crappy gasoline.

I'll repeat it here for your benefit:

The heated air intakes are designed to fight problems with low vapor pressure in early gasoline. By heating the inlet air charge you can make a poorer quality fuel ignite more readily. Thus more complete burning and less carbon buildup. This was absolutely essential in 1909 - 1927 because fuel quality was absolutely terrible. Ford was willing to sacrifice a bit of horsepower to make the engine less likely to carbon up the valves and intake / exhaust passages.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, December 19, 2010 - 01:48 pm:

The Corvair uses bakelite insulators under the carbs to prevent vapor lock after a hot run. Chris, you might try removing the insulators, at least for the 11 cool months in the Norwest Territory..


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Sunday, December 19, 2010 - 02:01 pm:

Royce,I read it the first time but do i belive it?? Yes i actually do think that must have been a reason [poor fuel with no ethonal!!] Burning corn as i type! With a grin! Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Christopher Lang - Brentwood Bay BC on Sunday, December 19, 2010 - 02:09 pm:

Ahh, the truck only freezes just after start up when the carbs are cold. Sitting there for a few minutes lets the tubes for the radio warm up anyway!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roy Stone Poca, WV on Sunday, December 19, 2010 - 02:24 pm:

It's good to remember all T's are no alike (just like humans) I was touring with a friend in Mountains of NC & both cars had same type of carbs, neither had hot air pipes, same type of gasoline etc; mine would ice up until near noon time each day, his wouldn't.
The next year I put a hot air pipe on & no more icing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Nevin Gough on Sunday, December 19, 2010 - 02:59 pm:

Roy, I agree. I used to run without a hot air pipe until my T stopped one warm and humid day. The carb was iced up! I have had a hot air pipe ever since, and no further problems.


Top of pagePrevious messageNext messageBottom of page Link to this message  By paul griesse granville,ohio on Sunday, December 19, 2010 - 03:37 pm:

I also run hot air pipes on my Ts---I think they run better WITH then WITHOUT. Thats just my opinion-----what else matters? paul


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money, Braidwood, IL on Sunday, December 19, 2010 - 04:03 pm:

I don't have a hot air pipe on mine since I haven't found one yet for the 26-7. Mine has iced up three times once to the point of stalling. The other two I was able to keep it just running until it melted and ran again. It can get a little uncomfortable depending on where you are at when it freezes up. When I locate a hot air pipe for mine it will have one again.

P.S. I have seen cars from the 60-70s have ice form on the throttle blades in the middle of summer while idling.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Berch on Sunday, December 19, 2010 - 04:31 pm:

I tried running mine without the heat pipe because I really wanted to use an air cleaner. It iced up immediately. I'm sure there are days when the weather conditions are right for it to not need one. I don't really want to put it on and take it off continually so I'll just leave it on. It would have been nice if Ford would have put a carb heat lever on the dash like small aircraft and a lot of the other cars of that era.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, December 19, 2010 - 04:33 pm:

The modern cars use either pre heated air going into the air intake, or heat in the manifold. I can't see why some Model T'rs don't like the heat pipe. I use them on all my cars in every altitude and in every weather and temperature condition I encounter. Yes I have driven them in snow, and yes in 100 degree plus and at 10,000' altitude. For those who were on the last Canyonlands tour in 2009, I drove all the way from Kanab to Brice Canyon the first day, in high gear with the hot air pipe in place.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roar Sand on Sunday, December 19, 2010 - 05:09 pm:

Doug,
Check part number 4582A in Lang's catalog.
Roar


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bamford on Sunday, December 19, 2010 - 09:02 pm:

Royce: "You will notice that your car goes slower when you install an intake heater, and faster when you remove it."

From less airflow restriction? Any other factors involved?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerome R. Hoffman, Hays KS on Sunday, December 19, 2010 - 11:22 pm:

Chris, in part it is because colder air sucked into the cylinder means it has more oxygen in the cylinder. Colder air is denser. Hot air will lean out the air/fuel ratio, cold will richen the mixture. This can be compensated by the mixture screw on the dash. Your modern car with a computer and fuel injection takes care of this without your your input. When the carb Ices up the mixture also gets a bit richer because the airflow becomes redistricted. If too redistricted the engine will stop running. With modern fuels the volatility is higher and so will run longer with less air, but it is still a balancing act. What do you want, fast car, reliable car, smooth running, great fuel economy? Remember reading about the fuel ecomony runs during the Model T era? Most of this cars had the late Vaporizer on them. In that case the fuel was hotter and naturally over came carburetor icing but only after start up. Not a popular carb in these colder areas of this country. By the way I am running a hot air pipe. On next Friday my plans are to make my am coffee shop run in my car. Temp may be around 25-30. I'll let you know how it goes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Monday, December 20, 2010 - 08:01 am:

I suspect the answer is more complex. The hot air pipes supplied by Ford went through endless variations, obviously Ford knew it was hurting performance and was trying to improve the problem. The pipe originally supplied on my '12 is a cast iron piece with a small inside diameter and much of the opening blocked byy the exhaust manifold. The pipe that came on the 1926 Fords with the final design NH carburetor is quite a bit larger in diameter, has a more gradual bend radius, and the bend radius is much further from the carburetor. It is a far morre complex part that must have been much more expensive to manufacture. No doubt there was a lot of testing that went into the decision to make the part so much more complex.

With some of the poorer designs of Model T carburetor, like the Holley G or Kingston L for example, removing the hot air pipe might not make much difference because the airflow is limited by the carburetor.

The airflow leading into the carburetor will reach higher velocity if there is no L-bend immediately before the carburetor. Any bend or restriction in the inlet causes a decrease in velocity which means an increase in pressure. This limits the ability to fill the cylinders with air rapidly, just like closing the throttle blade or choke blade would.

Internal combustion engines run on oxygen and fuel. Hot air molecules are larger and contain less oxygen. A hot humid day is worst of all, because water displaces even more oxygen. Cooler inlet air can support a more fuel for the same volume at a constant fuel / air ratio, yielding more horsepower.

You would need to instrument the engine and run it on a dynamometer to see exactly which factors are being affected the most by the inlet heat tube.

Bottom line, try it yourself. It won't take five minutes to realize the car runs better with it removed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Halpin on Monday, December 20, 2010 - 09:11 am:

Like I said in the beginning, there are going to be a lot of opinions on this. All valid (except the roofing tar, naturally) depending on time, place and condition.
As for me, I'm in no hurry, I live in Florida, I could leave it on or take it off without much difference. If I take it off, I'd want to fabricate some sort of filter though, seeing as how that carb sits so low on the engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Monday, December 20, 2010 - 03:24 pm:

I think we might have a confusion of terms here. Ice forming on the outside of the manifold isn't necessarily a problem, and in fact may even help. Just because there is frost/ice on the outside does not necessarily mean that there is ice on the inside. What Royce says about air rarification due to heat and humidity is a fact, not an opinion. What Frank say about the temperature drop is more or less true. He said the temperature "looses 70 degrees" I think it would be more accurate to say that it CAN lose 70 degrees. Here is a chart showing when icing conditions are most likely.


1

This is for an airplane, but I think it correlates to car driving pretty well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Conner - Sanford, NC on Monday, December 20, 2010 - 07:11 pm:

I'll go ahead and throw my two cents in with what I know about stove pipes and when they started coming off.

What's been said about the need to heat the air while the engine is cold is true on carbureted vehicles where the air/fuel is atomized in the intake. When the manifold is cold, the fuel has difficulty atomizing since the air surrounding it is heavy. Instead of turning to vapor, it pools, called flooding. The choke helps with this to an extent, but once the engine is running, it needs a large volume of air to run, and a leaner fuel mix as well. The stove pipe helps by running hot air into the manifold allowing the fuel to vaporize easier. BUT, once the engine is warm, or under a load, the demand for oxygen increases. With a fixed stove pipe that is constantly supplying warm air, the engine will continue to run rich hindering power. Of course this can be adjusted by the enrichment screw, but I feel like you'd constantly be fiddling with it to keep an even burn.

That all being said, there are exceptions. Theoretically, the ambient air temperature would determine how effective a stove pipe would be. I think that's one of the reasons why some on here swear by them and others shun them. There are other variables to like elevation, engine vacuum, the transit of Mars in relation to Pluto. Best advice I can give is see if it works for your car, if it doesn't snatch it off.

Henry was on to something when he added them though. Heat risers and stove pipes were put on cars well into 90's. Though, most were variable. The bulk of the ones I've seen were run by vacuum, though I have seen a few that were very crude electric versions, gotta love the 80's when they started putting computers in everything. Of course, when they finally went to multi-port fuel injection, stove pipes were no longer needed since the fuel was atomized in the cylinder instead of the intake and the injector itself handled the atomization.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money, Braidwood, IL on Monday, December 20, 2010 - 07:34 pm:

Roar, that is the one I had. Doesn't work on the 26-7 model with the innie manifold clamps. It needs the one with the tab in back not attached to the front as that one is. I'll keep looking. Thanks.


Top of pagePrevious messageNext messageBottom of page Link to this message  By tyrone thomas on Monday, December 20, 2010 - 10:04 pm:

So Im guessing my answer is: Heating the intake air is a good idea up to the point where its not a good idea?????? Ok then. Thanks. Anyone have an Advil? :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roar Sand on Monday, December 20, 2010 - 10:38 pm:

Sorry Doug, it looked so much like the one on my '26 with an NH that I thought it was the same.
As my "T" is some 5000 miles away, I couldn't go and take a look.
Roar


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Conner - Sanford, NC on Monday, December 20, 2010 - 10:39 pm:

Tyrone, I needed one just writing it! It's just like anything else with these cars, try it and see if it helps. If it doesn't there are plenty of T owners out there, I'm sure someone would take it off your hands.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman on Monday, December 20, 2010 - 10:43 pm:

Royce - I have a question. Tyrone initially asked what would be better; heating the air before or after the carburetor, or, both?

If I understand your explanation correctly, the original reason for the heat pipe was mostly for the purpose of dealing with the effects of poor fuel quality during the Model T era.

The heat pipe was obviously to heat the intake air BEFORE the carburetor; so I'm thinking that the one piece combination intake/exhaust manifolds (like the Anco or Wilmo) were designed to heat the intake air AFTER the carburetor:

In your opinion Royce, was that type of one-piece cast iron manifold basically for the purpose of dealing with the poor quality fuel also, and do you think it was any more (or less) effective, and, what do you feel would be the effects of that type manifold on a "T" with today's modern gasoline?

(sorry Royce; I guess that's 2 questions,...)

The reason I'm asking is because I have a very nice Wilmo combination manifold, and I'm thinking of installing it mostly because I feel that it is far less likely to ever warp from exhaust heat than like the separate original type exhaust manifolds do.

As far as fuel atomization, if it will not help, but will also not hurt, I'm going to install it mostly for the fact that it probably will never warp. What do you think,....thanks,.....harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Monday, December 20, 2010 - 11:36 pm:

I have an ANCO on the 14 touring. It runs really well.

I used to have a WILMO on my (now Constantine's) 13 touring. It ran pretty good too.

I don't know if any of this is related to the original subject of this thread or not. My opinion is the WILMO and ANCO manifolds are going to line up better with the ports because they are one piece. I don't know if there is any heat that affects anything or not.

I have a Holley Vaporiser on the '17 so there is another source of good running reliable Model T carburetion.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman on Tuesday, December 21, 2010 - 12:48 am:

I'm not sure if this is related to the original subject or not either; maybe at least "semi related". I can't decide if the hot exhaust warms the intake air (guess that'd be air/fuel mixture) or if the incoming air/fuel mixture cools the exhaust portion of the combination exhaust/intake manifold. I guess it's sort of a blend.

Good to hear that you had two of them and that both cars ran well. I'll be using the Wilmo in conjunction with a Holley NH; not sure yet if straight through or swayback.

Thanx Royce,.......harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ted Dumas on Tuesday, December 21, 2010 - 12:56 am:

The larger the air mass in the cylinder the more power produced, all other things being equal. Preheating the air reduces the air mass and should lower the output power. If the preheated air provides a more efficient combustion, then it might off set the reduction of air mass due to the warm air density.

My stock 24 touring (26 stock engine and transmission) will run 50 mph and has the hot air pipe. My 27 coupe, bored 0.060 and head milled 0.060 will run a bit faster, also with the hot air pipe. One day I'll pull the hot air pipe off and see what difference it makes.


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