hp upgrades

[p24-1953]

one of my first post was a question asking which upgrades got the most bang for the buck. well im slowly checking those off one by one. (overdrive, a/c) now im wondering what is the horsepower gain by switching to dual intake and exhaust? is it noticable and does it justify the cost? what is the horsepower gain? How about the gains from milling the head?

[55 Fargo]

I would imagine you would get about a 15 to 20 hp HP increase by going with dual exhaust/headers, shaved head to increase compression ratio, and with either a dual intake or a 2 bbl Holley Webber carb set-up.

I have been told by 1 individual, who has a couple of dual intake engines, that a 2 bbl carb on single intake, may be a better option, just an idea he had.

I think shaving the head and splitting the exhaust may give a good boost on it's own.

Some individuals have gone the full rebuild with high-perf cam, headers,dual carbs,shaved head, decked block, and electronic igntion, may get a 140 to 150 hp.

Even Earl Edgy's racer flahead engines may only be around the 200 hp range, full of bottom end, and typical inline 6 cyl torque, but not the top end hp of an overhead valve V8.

Not sure my answer helped, it is only observation, and speculation based on my readings on this forum over the years, hopefully those in the know can answer your questions in much more detail and experiantial acuracy.........Fred

[Young Ed]

Fred I plan to go the 2bbl route on my next truck. Not sure if its as good a gain but the linkage will sure be simpler

[Barabbas]

I asked George Asche the same question and his opinion was that by far the biggest bang for the buck in performance was dual exhaust. He didn't have any dyno type numbers but did his own "on the road" test. He found that dual exhaust improved his speed on his measured course by 7mph whereas dual carbs (1bbl ea.) increased the speed by only 2-3mph.

I don't remember any more details except his measured course was running in 3rd gear up a steep hill--

[55 Fargo]

Fred I plan to go the 2bbl route on my next truck. Not sure if its as good a gain but the linkage will sure be simpler

Hi Ed, I would agree the linkage and subsequent carb tuning may be simpler to adjust tune, set-up etc, I personally cannot attest to this, as I have no experience with the dual set-up.

I would think possibly the more modern Holley Webber 2 bbl carb is a progressive carb, and would be more efficient, and would operate possibly better, again no data or experience to back this up.

I also want to try this route Ed, 2 bbl carb, shaved hed .030, and split exhaust, I would think this would pack a bit more punch.

Hey let's face it, if we could get close to 25 more hp on a 100 hp engine, that is a 25 % gain in HP, so not bad.

An some of the late 50s 230 engines were up around the 125 hp mark, because of compression ratio increases.

I would think if you tricked out a 251 or a 265 engine you may easily get to 140 to 150 hp.........Fred

[Young Ed]

This is what I plan to run. Stock equipment for some 56-57 dodges and plymouths.

[Don Coatney]

Biggest single improvement is shaving the head to increase compression ratio. Next in line in my undocumented study is dual exhaust or other means to make the engine "breathe" better. Then add additional carburetion as required and top that off with a lumpy cam to increase duration (amount of time the valves are held open and the "lift" being how far open they actually are) but don't add any cam overlap (both valves open at the same time) as this eliminates any increase gain by shaving the head. Also clean up the porting (grinding away any excess metal to insure the manifold and engine block have no "ridge" where they mate) to insure good flow. Do not relieve (remove metal from the area of the engine block between the valves and the piston as pictured) as this will also negate any increase in compression ratio and be a step backwards.

[41/53dodges]

i dunno, i was just goin to be cheap and put on an electric blower to make a cheap charger

[Robert Horne]

My 36 Dodge engine had about 84 HP, where as my 56 Dodge engine had about 132 HP. The big difference from, 36 to 56 is cubic inch and compression. Dual exhaust, or a larger diameter exhaust pipe, is my next project, and should add a little more HP to the 56 engine, and the 5 speed trans should improve driving performance also.

[Cpt.Fred]

the most interesting question for me would be:

what is the biggest size 23" block i can get for my P10 so that i wouldn't have to go through the mods it would take to fit a long block engine?

it makes no sense to me to start modifying a 201cui block when i can start with, let's say, 230cui or hopefully even more.

i want the car to be as original as possible, cutting anything up is not an option for me.

also, i could start buying speed parts, like split headers and so on, and bolt them on the bigger engine once i have enough money for it.

the original engine will not be changed, either. i want the "hop up" process to be fully reversible.

it would be nice to open the hood and still have nearly the same looks but a lot more output than the actual 85hp

(or whats left of them after 70 years)...

dual exhaust makes the most sense to me, too.

it takes only one look to the factory setup to see that the engine is literally choked.

the ways the exhaust gas and the fuel/air mixture have to go are too different in lenght to allow a sophisticated power output, i guess.

Edited June 10, 2010 by Cpt.Fred

[Plymouthy Adams]

the idea to add dual carbs and dual exhaust to get the engine to breathe a bit deeper is all moot if you do not at the same time install a cam with a profile to take full advantage of the added ability to breathe.

[Robin (UK)]

Headers and dual exhaust...

Let the engine breathe and you'll notice a HUGE difference.

My P15 has now also got a dual carb intake and high-compression head.

But if you want to make a big impact... fast... go with the exhaust first.

Just my 2c worth (that's about 1.5p in English money)

[moose]

My experience has been that exhaust is key, and a good starting point. Your biggest expense will most likely be having the new exhaust system hung. After that you've got the building blocks for the rest, and you can go any direction you want- 2 carb, 2bbl...

And the sound... You don't need loud mufflers to have a good sound out of these engines. I've got "stock" quiet ones on my 55 and everybody loves the way it sounds. I wouldn't want glasspacks anymore, I drive with my kids all the time, and on the highway. Too raspy, and I want to preserve their hearing and mine.

[Reg Evans]

the most interesting question for me would be:

what is the biggest size 23" block i can get for my P10 so that i wouldn't have to go through the mods it would take to fit a long block engine?

it makes no sense to me to start modifying a 201cui block when i can start with, let's say, 230cui or hopefully even more.

i want the car to be as original as possible, cutting anything up is not an option for me.

Cpt Fred,

The largest 23" engine would be the 230. It can be bored out to approx. a 245 (maybe more) without causing any overheating problems. You will notice a big difference in power over the 201 with its smaller valves and port size.

[Cpt.Fred]

thanks, reg!

now all i have to do is look for a good one and have it milled and drilled and afterwards sent here... which might take a while due to a temporary shortage of funds:rolleyes:

which cars were there in, early to mid fifty dodge and plymouth, i guess?

thanks and back to topic:o

[Reg Evans]

My experience has been that exhaust is key, and a good starting point. Your biggest expense will most likely be having the new exhaust system hung. After that you've got the building blocks for the rest, and you can go any direction you want- 2 carb, 2bbl...

And the sound... You don't need loud mufflers to have a good sound out of these engines. I've got "stock" quiet ones on my 55 and everybody loves the way it sounds. I wouldn't want glasspacks anymore, I drive with my kids all the time, and on the highway. Too raspy, and I want to preserve their hearing and mine.

Amen to this moose. Especially the last part about mufflers. I installed the Langdon cast iron headers on my 42 Dodge coupe with a 230 and had the muffler man install 2 18" long Magnaflow mufflers right before the rear axle with a cross over up front. The car sounds great until about 1800 rpms when it suddenly breaks into what I call "dueling angry trombones". Very annoying and not music to my ears. This noise persists from about 1800 thru 3200 rpms. As soon as I can I'll be installing more conventional mufflers. The headers with dual exhaust and .050 off the head did increase the power noticeably.

[55 Fargo]

Amen to this moose. Especially the last part about mufflers. I installed the Langdon cast iron headers on my 42 Dodge coupe with a 230 and had the muffler man install 2 18" long Magnaflow mufflers right before the rear axle with a cross over up front. The car sounds great until about 1800 rpms when it suddenly breaks into what I call "dueling angry trombones". Very annoying and not music to my ears. This noise persists from about 1800 thru 3200 rpms. As soon as I can I'll be installing more conventional mufflers. The headers with dual exhaust and .050 off the head did increase the power noticeably.

Hi Reg, even with my smithy muffler,single exhaust, I find it loud at higher rpm on the highway.

I also want to go with headers,dual exhaust, but want a more mellow softer sound on the highway.

Will have to talk with moose on the headers.

Reg what induction/carb(s), are you running on the 42, and can we get pics of the engine?

BTW, saw your pics, great looking car, and nice shot of the Grandson with the Brook Trout..........Fred

[Reg Evans]

Fred,

Here's a shot of the engine right after I installed the headers and a 2 bbl intake manifold. The engine seemed to be running too rich with the 2 bbl so I installed a 1 bbl to 2 bbl adapter upside down so I could install my new Stromberg 1 bbl.

Passenger side

Dual exhaust before I went back to have a cross over installed trying to get rid of the annoying angry trombone sound.

[Young Ed]

Reg I see you made a lot more progress then I have on the whole 2bbl thing. How do you like it besides the loud exhaust?

[1937 Dodge]

Great looking engine Reg.

[Reg Evans]

Actually Ed,I didn't like the way it ran with the 2 bbl. Too rich or a vacuum leak er something so instead of removing the 2 bbl manifold I installed a 1 to 2 bbl adapter upside down so I could run my new Stromberg 1 bbl. Sort of a mini velocity stack.

[Young Ed]

Wow thats interesting. Hope I don't have that same issue.

[Don Coatney]

Ed;

I dont think you will have that issue unless you are using a SpitSfire head.

[Reg Evans]

Ed;

I dont think you will have that issue unless you are using a SpitSfire head.

The likelyhood of that ever happening is next to zero since I have only seen one in 61.75 years.

[BobT-47P15]

For a more mellow exhaust sound, use the longer mufflers.....the short

ones get pretty abrasive. Reg, your Spitsfire engine looks good.......