Thickstun intake

[Plymouthy Adams]

The Wind in the Willows.....Mr. Toad was a speed addict of the first kind.....I think he is better represented today by no other than Mr. Bean.....in real life our boy Atkins has crashed his fair share of fast cars......If I had his money...I would probably  have done no less...

Edited October 22, 2021 by Plymouthy Adams

[ratbailey]

3 hours ago, Loren said:

The urge to modify is very strong among gear heads.

Sometimes they make smart choices and sometimes the other kind.

If your not Smokey Yunick or Barney Navarro or Doane Spencer perhaps you should stick to what you know works.

It takes a lot of reading and research. Some guys refuse to do the work.

If you live in the L.A. area you will find Jay Leno at the annual Throttlers Picnic.

He's not spouting off about the great cars he owns and his next project.....he's listening.

He wants to know what the guys who did it back in the day are saying.

It's the history, the stories, he wants to hear. He's comparing notes and sorting out fiction from fact.

He does not care who makes the best disc brake kit or T5 adaptor.

I have a car that he has that he bought from a guy I know.

It is bone stock with a 750 engine prone to head gasket problems.

Mine (I have more than one) have later 850 engines that are reliable.

His has a 3 speed transmission, mine have later 4 speeds.

His has drum brakes, mine have later disc brakes.

It is a whole lot easier to make the switches I have than to try and preserve the original stuff.

I did it because it was cheaper and easier and added performance at a time when I didn't have a lot of money.

I drove one car in particular everyday.

His car is a museum piece, mine were daily drivers.

I am certain he knows everything I know about those cars and with one phone call he could find out more than I know.

The car he has gives him pleasure.

The cars I have gave me transportation.

It's a balance between originality and utility. Jay can afford originality, at the time I could not.

But since I got used to the way my cars drove....I am not going back, they work.

I've always admired Jay. He spent plenty of time in the showbiz trenches, sleeping in his Buick Roadmaster while barnstorming the country. He grew up in the next town over from where I grew up, 20 years before, and the local paper never got tired of running "local boy makes good" stories about him, or pictures from his high school yearbook. Boy, are we getting far off topic ?

[desoto1939]

etno:  I do understand hot rodding. I grew up in the 50's and hung out with some very hot and fast cars.  My point was to get the conversation flowing about the upgrades people put on their cars. As stated I am more of a purist in the hobby and have been able to maintain my 1939 Desoto for the past 34+ years as an original car with original equiptment.  I am not putting down the guys or gals that want to modify their engines or drive lines.  It is their car and they have every right to do so. What I am trying to understand is why spending the dollars for the looks and maybe slight performance changes and updates.

 

I like to get people thinking and commenting. This is what keeps the hobby interesting.

 

Rich Hartung

desoto1939@aol.com

[dwest999]

Rich, thanks for getting the discussion going.  Some of us enjoy the purity of an all original example, while other like to go the hopped up route.  In the end, we all love vintage Mopars and that's all that really matters.

[Plymouthy Adams]

food for thought......or stir the pot.....whatever BUT, if Ma Mopar was to say built a throwback car and resurrect the the P15 Bz Cp do you for one second think it would have a flathead in it today.......drum brakes all around...a arm locked with the shock to render them basically ineffective....list can go on but you see the point.   Technology marches to music many folks just refuse to dance to....

[Loren]

Okay back to intake manifolds.

I have a Thickstun and it doesn’t take flow bench to figure out that it is better than an Offenhauser (which I also have).

Then there’s the Edmunds.....

When you look at the two of them (Edmunds and Thickstun) the Edmunds seems like it has the edge for flow.

It certainly mounts the carburetors higher with a more direct flow, if longer.

The Thickstun is lower and has a novel way of attempting to achieve an even flow but there is a more pronounced 90 degree turn under the carburetors.

So which one is going to work better?

I am leaning to the Thickstun for a mild street engine and the Edmunds for something with more steam.

Any thoughts?

[Andydodge]

Just to add something that hasn't been mentioned in this discussion............the twin intakes for the 23" Dodge & Plymouth engines makes sense to me as I'm a hotrodder however the question was whether  a twin/triple intake for the 25" DeSoto/Chrysler engine was being planned..........here in Oztralia the 25" engine was much more common from WW2 onwards than the 23" Dodge/Plymouth engine.......both were available, sometimes in the same year in the same model mopar however the 25" engine is still the most numerous being used up until 1962 in Oz Chrysler cars and from what I've learnt its also the case in Canada from the late 30's to the late 50's that the 25" engine was the standard installation..............both these situations would lead me to think that a 25" twin intake would be more popular than just to satisfy the American DeSoto/Chrysler fans which I think would have a limited market....here in Oz and possibly Canada there maybe exists a ready untapped market.............Andy Douglas     

[Sniper]

I have 1 inch spacers between my throttle bodies and the Thickstun intake.  Went that route to adapt the Weber based throttle bodies bolt pattern to the Thickstun's.  Plenty of room to go taller if needed. 

[ratbailey]

Can anyone recommend papers or books on aftermarket intakes, with facts and stats? I'd be interested to know about the science behind this stuff, or just some general reading about how to draw my own conclusions about aftermarket add ons for old engines. I'm sure there's plenty on the interwebs, but if anyone has favorite reading material, I'm all ears.

 

In a five second search, I came up with this: https://www.musclecardiy.com/cylinder-heads/build-flow-bench-port-flow-testing-cylinder-heads-part-3/

The author mentions Smokey Yunick's Power Secrets. Bet that's a good read.

Edited October 24, 2021 by ratbailey

[Bryan]

9 hours ago, Loren said:

 

I am leaning to the Thickstun for a mild street engine and the Edmunds for something with more steam.

Any thoughts?

I seem to remember from a motorcycle engine hop up book that longer intakes are more suited for lower rpms.   Intakes are not to be polished mirror smooth..

[greg g]

In the downloads area is an article from a 1950s magazine that details common changes, like adding dual intakes, exhaust, raising compression ratio, boring, porting, and a couple of other changes that were state of the art at the time.  This article  was submitted by member Mark Duggan, if you can't find it you might contact him to see if he has it as a pdf file he might e mail.  

 

There is also a chart for all flat head sixes illustrating the compression ratio changes that occur through planing or milling cylinder heads by various amounts.  This presupposes the head is stock before machining it. Which unless we know the history of the car or engine and previous work done to it is guess work.  This was submitted by Don Coatney.  

 

If you go through the engine specs, the factory understood the principles  of hot rodding, other wise all our engines would have been 87 HP 201s but they knew how to make changes to go from 87 to 132 with basically the same engine with some souping up applied up to what the bean counters and day to day reliability would allow.

 

We know the factory could have easily built 250 hp fire breathers but they wouldn't have been very good at commuting or getting groceries.

Edited October 24, 2021 by greg g

[Andydodge]

 My understanding is that long intake runners or manifold ports are in theory more suited to developing torque with shorter runners more suited to high RPM and higher horsepower......however bore/stroke/cam specs/head porting,valve size, piston design and a heap of other things can affect the engines power band.........when I was assembling the bits for the 230 I was intending to use in my 41 Coupe I had a twin carb intake, split cast iron exhaust manifolds, higher compression finned head, reground cam  , a balanced reciprocating assembly,ie, crank,rods,pistons,flywheel & clutch and all new valves,lifters,springs,oil pump& timing chain & gears.....basically a new engine apart from the block which would have had some mild porting with gasket/port/manifold matching ...........as a single carbed factory stock 230 had a final HP rating of 132 horses I was hoping to see something around 180-200 tho' that may have been wishful thinking.......sold the lot before really getting into it so will probably never know...but good to think about........lol.............Andy Douglas      

Edited October 25, 2021 by Andydodge
more info

[Sniper]

Longest commonly available intake is a tunnel ram.

 

They are not known for low end torque improvements.

 

 

[Frank Gooz]

With the input i have read. What about keeping the carbs cool. Heated intake, And cooler carbs by using a phenolic spacer.

 

[Loren]

3 hours ago, Frank Gooz said:

With the input i have read. What about keeping the carbs cool. Heated intake, And cooler carbs by using a phenolic spacer.

 

 

Over the automotive period, the chemistry of gasoline has changed dramatically.

In the 1920s a change in refinery techniques caused a rush to exhaust heated carburetors. Apparently gasoline got "oily" and hard to vaporize. Model T Fords came equipped with these crazy "Vaporizer Carburetors" that included the exhaust manifold (1926-27).

Currently the Federal Government mandates 9 different custom blends of gasoline for local and seasonal use.

The purpose of manifold heat is to counter "Icing". As gasoline vaporizes it cools and since air always includes water vapor, it can form ice in the manifold. That ice cools the carburetor and blocks its passages. Since for every pound of fuel the engine ingests ideally 13.2 pounds of air, that can be a lot of water!

The whole thing is a balancing act.

Heat expands the air so the engine gets less of it. Which hurts power output but if ice becomes problematic the engine won't run at all.

Engineers finally figured out that "perfect" atomization of the fuel displaces air, which is why carburetors CAN get better mileage and power than fuel injection. A carburetor spews globules of fuel (along with atomized fuel) which displace less air and that is the reason why.

The fix for that problem is direct injection of fuel into the combustion chamber. Thus there is no displacement of power producing air. Think the efficiency of diesel.

Fuel also needs to be dense. Again it's a balance.

Engineers find the worst case situation and add things like phenolic spacers until the problems go away.

One of the things that get tossed are the tin heat shields over the fuel pump. Those things solved a problem (vapor lock) yet guys throw them away.

There are no "off the shelf" categorical fixes. Each engine, each situation has its fixes when a problem is found.

My general rule is that if the engineers felt something was needed, you'd better keep it and if it works, don't fix it.

If you identify a problem, then find a fix. Solutions in search of a problem are just wheel spin.

[Bryan]

Anything has to be better than the stock intake manifolds...

[Plymouthy Adams]

yeah...that is why Chrysler failed to sell these engine for the decades they did....you sliding scale is askew

[Bryan]

2 hours ago, Plymouthy Adams said:

yeah...that is why Chrysler failed to sell these engine for the decades they did....you sliding scale is askew

Well, do you think there's room for improvement in what you're seeing?   Maybe I worded it kind of harsh, but the intake should not be like that for optimum flow.

[Plymouthy Adams]

if the engine needed optimum flow I would agree......as long as the fuel stays atomized.....job done.!

 

 

[greg g]

The only thing I am sure of is that fluids and air don't like 90 degree corners.  So between the thick stun and the Offy, it pretty easy to tell which is friendlier to flow.  That said, no mater what, the engine will only pump a finite amount of air.  Putting extra entrances in won't change that.  Its like entering a theater,  no matter how many people are in the lobby, when the doors to the seats open, only a finite number cab pass the doors to the aisles. 

 

As far as the inner surfaces go, rougher is better to keep the incoming charge mixed up.  If you look at the old 413 wedge motors with their long cross flow intakes, and even the slant six, Chrysler seemed to have intake engineering covered.