Jump to content

Split header - dual exhaust - reduced torque?


Thsmedley

Recommended Posts

30 minutes ago, sser2 said:

This is completely wrong. Multiple carbs indeed increase power, but only at steady high speed. The tradeoff is deteriorated performance at low speed and poor acceleration. This is because with 2 carbs the air flow speed at each venturi is only 1/2 compared to single carb, resulting in poor fuel atomization at lower speeds. Increased air flow increases power only at the expense of higher fuel consumption, so there is no better fuel economy. Fuel economy is worse with multiple carbs because more fuel gets into cylinders in liquid form due to poor atomization. This liquid fuel does not burn and is wasted into exhaust.

 

Again a very broad brush you are painting with. If the original carb was at or close to the upper end of the capacity of the engine then yes the issues you point to could indeed occur with an additional carb added to the mix. However if the opposite is true and the original carb is at or near the bottom of the capacity of the engine a second carb as long as the combined do not exceed the capacity will absolutely increase performance and can and did in my case increase fuel economy. This is especially true if you help open the breathing on the exhaust side. 

 

Look at all the production vehicles (cars, bikes, planes etc) that well paid and very educated engineers have designed with multiple carbs. Were these engines only efficient at high speeds and show poor acceleration? Do all those drag cars with multiple carbs exhibit poor acceleration?   

  • Like 1
Link to comment
Share on other sites

1 hour ago, sser2 said:

This is completely wrong. Multiple carbs indeed increase power, but only at steady high speed. The tradeoff is deteriorated performance at low speed and poor acceleration. This is because with 2 carbs the air flow speed at each venturi is only 1/2 compared to single carb, resulting in poor fuel atomization at lower speeds. Increased air flow increases power only at the expense of higher fuel consumption, so there is no better fuel economy. Fuel economy is worse with multiple carbs because more fuel gets into cylinders in liquid form due to poor atomization. This liquid fuel does not burn and is wasted into exhaust.

My expierence with adding dual carbs and headers is the exact opposite of what you describe. 

Link to comment
Share on other sites

1 hour ago, hkestes41 said:

Look at all the production vehicles (cars, bikes, planes etc) that well paid and very educated engineers have designed with multiple carbs. Were these engines only efficient at high speeds and show poor acceleration? Do all those drag cars with multiple carbs exhibit poor acceleration?   

Very educated engineers equipped virtually all NORMAL (I mean not racing) cars not with multiple carbs, but with double barrel sequential open carbs. In drag racing, they don't accelerate like you would do in normal driving. Engine is raced to top speed before car even starts moving. This is poor example to prove your point.

Link to comment
Share on other sites

The big flatheads in heavy duty trucks had two single bbl carbs and split exhaust for a reason...these trucks were not speed demons but needed to produce power at launch throughout the engine speed range...these carburetors were designed and adjusted to work well this way.  And it's these adjustments that are key to making the dual induction work.  With increased fuel consumption, fuel economy will begin to drop, but properly adjusted induction with increased exhaust will generate more power to the pavement.

 

As a side note, I recently upgraded the exhaust on my Dodge Cummins from 3.5" to 4"...after several thousand miles, I could see that my economy had decreased by about 1 mpg, but passing at speed rarely required a downshift as putting my right foot into it motivated that beast very quickly...LOTS of fun that way :cool:

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

39 minutes ago, JBNeal said:

The big flatheads in heavy duty trucks had two single bbl carbs and split exhaust for a reason...these trucks were not speed demons but needed to produce power at launch throughout the engine speed range...these carburetors were designed and adjusted to work well this way.  And it's these adjustments that are key to making the dual induction work.  With increased fuel consumption, fuel economy will begin to drop, but properly adjusted induction with increased exhaust will generate more power to the pavement.

 

As a side note, I recently upgraded the exhaust on my Dodge Cummins from 3.5" to 4"...after several thousand miles, I could see that my economy had decreased by about 1 mpg, but passing at speed rarely required a downshift as putting my right foot into it motivated that beast very quickly...LOTS of fun that way :cool:

I was about to bring up the same point.  If dual carbs and dual exhaust didn't make any difference for low and mid-range rpms, Dodge would not have equipped the flatheads in multi-ton trucks with these features.

  • Like 1
Link to comment
Share on other sites

1 hour ago, sser2 said:

Very educated engineers equipped virtually all NORMAL (I mean not racing) cars not with multiple carbs, but with double barrel sequential open carbs. In drag racing, they don't accelerate like you would do in normal driving. Engine is raced to top speed before car even starts moving. This is poor example to prove your point.

 

Wrong again. Your exact quote was "Multiple carbs indeed increase power, but only at steady high speed. The tradeoff is deteriorated performance at low speed and poor acceleration." Drag racing is the ultimate acceleration test of a vehicle. It starts from a dead stop and accelerates for a 1/4 mile. Yes the RPMs are brought up prior to launch, but it is in no way "steady high speed" it is full on acceleration. 

 

Below is just a partial list of the normal factory equipped domestic cars that have had multiple carbs not to mention foreign cars. 

 

The following is a listing of multiple carburetor manifolds used by USA manufacturers as original equipment compiled by The Carburetor Shop. We believe all information presented to be correct, however, the listing is not complete. We would welcome documented additions and/or corrections.

 

 

 Make         Years      Engine   Application     Casting number     Material       Type

 

 Buick              1941               248      40, 50                                                                        Cast iron      2x2

 Buick              1941               320      60, 70, 90                                                                  Cast iron      2x2

 Buick              1942               248      40, 50                                 1326503-2                    Cast iron      2x2

 Buick              1942               320      60, 70, 90                                                                  Cast iron      2x2

 Buick              1964               425                                                  1370316                        Cast iron      2x4

 Buick              1965               425                                                  1370316                        Cast iron      2x4

 Buick              1966               425                                                   1370316                       Cast iron      2x4

 

 Cadillac     1930-1937          452                                                                                                                2x1

 Cadillac     1931-1937          368                                                                                                                2x1

 Cadillac     1938-1940           431                                                                                                               2x2

 Cadillac          1955                 331      El Dorado                           1463205                       Cast iron      2x4

 Cadillac          1956                 365      El Dorado                           1464580                       Cast iron      2x4

 Cadillac          1957                                                                           1469263                      Cast iron      2x4

 Cadillac           1957                365      El Dorado                            1465950                      Cast iron      2x4

 Cadillac           1958                365      El Dorado                            1469689                      Cast iron      3x2

 Cadillac           1959                390      El Dorado                            1472225                       Cast iron      3x2

 Cadillac           1960                390      El Dorado                            3512080                       Cast iron      3x2

 

 Chevrolet        1953                  235      Corvette                                                                 Aluminum       3x1

 Chevrolet        1954                  235      Corvette                                                                 Aluminum       3x1

 Chevrolet         1956                 283                                                    3731394                  Aluminum       2x4

 Chevrolet         1957                 283                                                    3739653                   Aluminum       2x4

 Chevrolet         1958                 283                                                    3739653                    Aluminum       2x4

 Chevrolet         1959                 283                                                    3739653                    Aluminum       2x4

 Chevrolet         1960                 283                                                    3739653                    Aluminum       2x4

 Chevrolet          1961                283                                                   3739653                     Aluminum       2x4

 Chevrolet          1958                348                                                   3749948                     Cast iron         3x2

 Chevrolet          1959                348                                                  3749948                      Cast iron         3x2

 Chevrolet          1960                348                                                  3749948                      Cast iron         3x2

 Chevrolet          1961                348                                                  3749948                      Cast iron         3x2

 Chevrolet    1962          409                               3814881             Aluminum       2x4

 Chevrolet    1963          409                               3814881             Aluminum       2x4

 Chevrolet    1964          409                               3814881             Aluminum       2x4

 Chevrolet    1965          409                               3814881             Aluminum       2x4

 Chevrolet    1963          396      Z-11                     3830623             Aluminum       2x4

 Chevrolet    1967          427      400 HP                   3894382             Aluminum       3x2

 Chevrolet    1967          427      435 HP                   3894374             Aluminum       3x2

 Chevrolet    1968          427      400 HP                   3937795             Aluminum       3x2

 Chevrolet    1968          427      435 HP                   3919852             Aluminum       3x2

 Chevrolet    1969          427      400 HP                   3937795             Aluminum       3x2

 Chevrolet    1969          427      435 HP                   3937797             Aluminum       3x2

 Chevrolet    1969          302      Z-28 (cross ram)         5841130             Aluminum       2x4

 

 Chrysler     1959          413      300-E                    2264877             Cast iron      2x4

 Chrysler     1960          413      300-F                    2264877             Cast iron      2x4

 Chrysler     1961          413      300-G                    2264877             Cast iron      2x4

 Chrysler     1962          413      300-H                    2264877             Cast iron      2x4

 Chrysler     1963          413      300-J (right side)       2129985             Aluminum       2x4

 Chrysler     1963          413      300-J (left side)        2129987             Aluminum       2x4

 Chrysler     1964          413      300-K (right side)       2129985             Aluminum       2x4

 Chrysler     1964          413      300-K (left side)        2129987             Aluminum       2x4

 

 Dodge        1956                   D-500 (early)            1733878             Cast iron      2x4

 Dodge        1956                   D-500 (late)             1733978             Cast iron      2x4

 

 Duesenberg   1931          420      (Supercharged)                                              2x2

 Duesenberg   1932          420      (Racing only)                                               2x2

 

 Ford         1956                                            EDB-9424-C          Aluminum       2x4

 Ford         1956          312      (experimental)           ECZ-9424-C          Aluminum       2x4

 Ford         1957          312                               ECG-9424-D          Aluminum       2x4

 Ford         1963          406                               None                Aluminum       3x2

 Ford         1963          427      Low riser                C3AE-9425-H         Aluminum       2x4

 Ford         1963          427                               C3AE-9425-K         Aluminum       2x4

 Ford         1967          427                               C7AE-9424-A         Aluminum       2x4

 

 Hudson       1952          232      Wasp                                         Cast iron      2x1

 Hudson       1952          262      Super Wasp                                   Cast iron      2x1

 Hudson       1952          308      Hornet                   307184              Cast iron      2x1      

 Hudson       1953          202      Jet                                          Cast iron      2x1

 Hudson       1953          308      Hornet                   307184              Cast iron      2x1

 Hudson       1954          202      Jet                                          Cast iron      2x1

 Hudson       1954          262      Wasp, Super Wasp                             Cast iron      2x1

 Hudson       1954          308      Hornet                   307184              Cast iron      2x1

 Hudson       1955          202      Jet                                          Cast iron      2x1

 Hudson       1955          308      Hornet                   5325118             Cast iron      2x1

 Hudson       1956          308      Hornet                   5325118             Cast iron      2x1

 

 Mopar                                                        1634285             Cast iron      2x4

 Mopar        1956          315      500 'A' Option           1735917             Aluminum       2x4

 Mopar        1957          315      500 'A' Option           1735917             Aluminum       2x4

 Mopar        1957          318      'C' body                 1822004             Cast iron      2x4

 Mopar        1958          318      'C' body                 1822004             Cast iron      2x4

 Mopar        1958          350      'C' body                 1827899             Cast iron      2x4

 Mopar        1958          383      'C' body                 1827899             Cast iron      2x4

 Mopar        1959          350      'C' body                 1827899             Cast iron      2x4

 Mopar        1959          383      'C' body                 1827899             Cast iron      2x4

 Mopar        1959          413      385 H.P.                 1854817             Cast iron      2x4

 Mopar        1960          350      'C' body                 1827899             Cast iron      2x4

 Mopar        1960          383      'C' body                 1827899             Cast iron      2x4

 Mopar        1960          413      385 H.P.                 1854817             Cast iron      2x4

 Mopar        1961          350      'C' body                 1827899             Cast iron      2x4

 Mopar        1961          383      'C' body                 1827899             Cast iron      2x4

 Mopar        1961          383      'C' body (left side)     1947162             Aluminum       2x4

 Mopar        1961          383      'C' body (right side)    1947163             Aluminum       2x4

 Mopar        1961          413      385 H.P.                 1854817             Cast iron      2x4

 Mopar        1961          413      'C' body (left side)     1947162             Aluminum       2x4

 Mopar        1961          413      'C' body (right side)    1947163             Aluminum       2x4

 Mopar        1962          383      'C' body                 1827899             Cast iron      2x4

 Mopar        1962          413      385 H.P.                 1854817             Cast iron      2x4

 Mopar        1962          413      'B' body max             2402726             Aluminum       2x4

 Mopar        1963          426      'B' body max             2402726             Aluminum       2x4

 Mopar        1963          426      'B' body max perform II  2402728             Aluminum       2x4

 Mopar        1964          426      'B' body max perform     2402720             Aluminum       2x4

 Mopar        1964          426      'B' body S/S strip -     2468045             Aluminum       2x4

 Mopar        1965          426      'B' body S/S strip -     2536900             Magnesium      2x4

 Mopar        1966          426      'B' body hemi w/Carter   2531921             Cast iron      2x4

 Mopar        1966          426      'B' body hemi w/Holley   2946278                            2x4

 Mopar        1967          426      NASCAR                   2536900             Magnesium      2x4

 Mopar        1967          426      W/marking 'DPCD'         2780543,4                          2x4

 Mopar        1967          426      W/pentastar (late)       2780543,4                          2x4

 Mopar        1968          426                               2536900             Magnesium      2x4

 Mopar        1968          426      W/pentastar              2780543,4                          2x4

 Mopar        1969          426      W/pentastar              2780543,4                          2x4

 Mopar        1969          440      'B' body (Edelbrock)     3412046             Aluminum       3x2

 Mopar        1970          440      'B' body (Edelbrock)     3412046             Aluminum       3x2

 Mopar        1970          340      'E' body (Edelbrock)     3418681             Aluminum       3x2

 Mopar        1970          426      W/pentastar              2780543,4                          2x4

 Mopar        1970          440      'B', 'C', 'E' body       2946275             Cast iron      3x2

 Mopar        1970          440      'B', 'C', 'E' body       2946276             Cast iron      3x2

 Mopar        1971          426      W/pentastar              2780543,4                          2x4

 Mopar        1971          440      'B', 'C', 'E' body       2946276             Cast iron      3x2

 Mopar        1972          440      'B', 'C', 'E' body       2946276             Cast iron      3x2   

 

 Nash         1951          235      5160                                                        2x1

 Nash         1952          252      Healy                                                       2x1

 Nash         1952          252      Jetfire                                                     2x1

 Nash         1953          252      Healy                                                       2x1

 Nash         1953          252      Jetfire                                                     2x1

 Nash         1954          252      Jetfire                                                     2x1

 Nash         1955          195      5540                                                        2x1

 Nash         1955          252      Jetfire                                                     2x1

 Nash         1956          252      Ambassador                                                  2x1

 

 Oldsmobile   1957          371      J-2                      571145              Cast iron      3x2

 Oldsmobile   1958          371      J-2                      571145              Cast iron      3x2

 Oldsmobile   1966          400      442(3 versions AL,AU,AZ) 393238              Cast iron      3x2

 

 Packard      1955          352                               440856              Cast iron      2x4

 Packard      1956          374                               440856              Cast iron      2x4

 

 Plymouth     1956                   (over the counter)       1732479             Cast iron      2x4

 Plymouth     1956                                            1735919             Aluminum       2x4

 Plymouth     1956          303      Fury                     1733878             Aluminum       2x4

 Plymouth     1957          303      Fury                     1733878             Aluminum       2x4

 Plymouth     1957          318                               1822004             Cast iron      2x4

 

 Pontiac      1956          316      (production)             523554              Cast iron      2x4

 Pontiac      1956          316      (developmental)          D-32960             Cast iron      2x4

 Pontiac      1957          347                               528533              Cast iron      3x2

 Pontiac      1958          370                               529371              Cast iron      3x2

 Pontiac      1959          389                               532422              Cast iron      3x2

 Pontiac      1960          389      (Late production)        535552              Cast iron      3x2

 Pontiac      1960          389      (Early production)       536194              Cast iron      3x2

 Pontiac      1961          389                               538202              Cast iron      3x2

 Pontiac      1961          389      Super duty               540510              Aluminum       3x2

 Pontiac      1961          421      Super duty               542991              Aluminum       2x4

 Pontiac      1962          389                               541690              Cast iron      3x2

 Pontiac      1962          421                               541690              Cast iron      3x2

 Pontiac      1962          421      Super duty               542991              Aluminum       2x4

 Pontiac      1962          421      (over the counter)       54299               Aluminum       2x4

 Pontiac      1962          421      Super duty               9770319             Aluminum       2x4

 Pontiac      1962          421      Super duty               9770859             Aluminum       2x4

 Pontiac      1963          389                               9770275             Cast iron      3x2

 Pontiac      1963          421                               9770275             Cast iron      3x2

 Pontiac      1963          421      Super duty               9770859             Aluminum       2x4

 Pontiac      1963          421      Super duty               9772128             Aluminum       2x4

 Pontiac      1963          421      Super duty               9772598             Aluminum       2x4

 Pontiac      1964          389                               9775088             Cast iron      3x2

 Pontiac      1964          421                               9775088             Cast iron      3x2

 Pontiac      1965          389                               9778818             Cast iron      3x2

 Pontiac      1965          421                               9778818             Cast iron      3x2

 Pontiac      1966          389                               9782898             Cast iron      3x2

 Pontiac      1966          421                               9782898             Cast iron      3x2

 Pontiac      1969          303      RA V                     478489              Aluminum       2x4

 Pontiac      1969          303      RA V                     546235              Aluminum       2x4

 

 Studebaker   1962          304                               1555811             Aluminum       2x4

Edited by hkestes41
  • Like 1
Link to comment
Share on other sites

10 hours ago, sser2 said:

This is completely wrong. Multiple carbs indeed increase power, but only at steady high speed. The tradeoff is deteriorated performance at low speed and poor acceleration. This is because with 2 carbs the air flow speed at each venturi is only 1/2 compared to single carb, resulting in poor fuel atomization at lower speeds. Increased air flow increases power only at the expense of higher fuel consumption, so there is no better fuel economy. Fuel economy is worse with multiple carbs because more fuel gets into cylinders in liquid form due to poor atomization. This liquid fuel does not burn and is wasted into exhaust.

Im not sure where you are doing your research.

But on these engines with siamesed intake ports you are "full of misinformation " to say it nicely.

A single carb is the least efficient method of fuel distribution with a design such as this. Cyls 3 and 4 run rich and cyls 1 and 6 much leaner. Now aint that fuel distribution efficiency? Oh its adequate, but its not more efficient at all.

the most efficient is a carb for each intake port all 3 balanced to provide the best fuel distribution and atomization for each set of cylinders per port.

Multi carbs good only at  high speeds and WOT?

I think you missed the boat on this.

They are great in all ranges on this engine. Better fuel distribution to all 3 ports and much more efficient fuel atomization.

No problem you can believe what you want, but the reality is quite the opposite of what you are claiming.

I can go on much further to refute your claims and to demonstrate how a multi carb set up works more efficiently in all ranges, the benefits and the increased HP and fuel economy. 

However you would come up with some reason contrary, its quite evident you dont like multi carb setups and better exhaust flow for your own uninformed reasons.

I believe others have also stated their responses in disagreement to your beliefs.

Edited by 55 Fargo
  • Like 1
Link to comment
Share on other sites

11 hours ago, sser2 said:

Very educated engineers equipped virtually all NORMAL (I mean not racing) cars not with multiple carbs, but with double barrel sequential open carbs. In drag racing, they don't accelerate like you would do in normal driving. Engine is raced to top speed before car even starts moving. This is poor example to prove your point.

I'm not sure where you are getting your information but you are comparing modern engines with basically antique/obsolete technology.  I agree that with modern vehicles it is very difficult to improve on the stock intake/exhaust because there was actually "engineering" involved with their design.  In the earlier years these engines were engineered just enough (not much) to meet target specifications.  Once met no further engineering was needed.  Even the factory offered upgraded intakes and exhausts among other items during the muscle car years and even before.  Examples would be the Super Stock Dodges, 300 Hemis, GTO's........  Now for late models - In the late 90's Ford lowered the hood lines of the Mustang, by doing so the Cobra intake was pancaked and the car was released to the public without meeting it's advertised HP.  Subsequently there was a recall that replaced the intake with a hand ported one and replacing the exhaust with a more free flowing system, thereby increasing the HP to the advertised amount, so it does improve things.  Technology improves over time also, look at what people called high performance cars in the 80's verses today.  A 81 fuel injected vette made 150hp in California, now 600+ and better mileage / driveability also.

When I was racing Pontiacs in the 90's, if I dropped the hammer at max RPM as you state above I would have left parts at the lights.  

Please understand multiple carbs, especially on these long Siamesed port engines, do make improvements all around with the only downside is a bit more tuning.  I have done it and witnessed it first hand, you?

  • Like 2
Link to comment
Share on other sites

     Lets make this even simpler......single carb spaced over the center port feeds that port rich, the the 2 pistons in the middle receiving the lions share of the fuel.

The 2 outer ports are lean and do not run as well as the center port due to lack of fuel.

       It runs well but not efficiently, nor has it reached its potential in horsepower.

However by placing 2 carbs of the same size as the stock carb between ports all ports get fed the same amount of fuel thus improving both horsepower and mileage.....as if it was being fed by one carb efficiently.

Headers or some form of split manifolds are needed to to round out the package so the engine may breathe at its best.

       I never change the cam because I am not a rumpity rappity raspy guy.....I like quiet cars.

 

Link to comment
Share on other sites

6 hours ago, Frank Elder said:

     Lets make this even simpler......single carb spaced over the center port feeds that port rich, the the 2 pistons in the middle receiving the lions share of the fuel.

The 2 outer ports are lean and do not run as well as the center port due to lack of fuel.

       It runs well but not efficiently, nor has it reached its potential in horsepower.

However by placing 2 carbs of the same size as the stock carb between ports all ports get fed the same amount of fuel thus improving both horsepower and mileage.....as if it was being fed by one carb efficiently.

Headers or some form of split manifolds are needed to to round out the package so the engine may breathe at its best.

       I never change the cam because I am not a rumpity rappity raspy guy.....I like quiet cars.

 

Ok!  Wait a minute.  I see this argument all the time.  Not picking on Frank but the air fuel mixture is set in the carb.  It then gets delivered to the manifold and gets sucked to which ever port is calling for it.  If the mixture is correct as it enters the manifold, how can it change to a leaner mix in a closed tube?  If it gets leaner where does the gas go??  Seems to me unless air is entering some where south of the carburetor. I will stipulate the center intake might be provided a fuller charge because the fuel air has to travel a shorter and more direct path to the cylinder but if all cylinders are pumping equal volumes the charge would be the volume and contain the same amount of gas.  I can see were a second carb shortens the distance and may make the system more efficient but since each carb is only half the cfms based on bernullis principles and venturies effect both charges might actually be leaner than that provided the single carb. Things that make you go hmmmm.

And if distance were a critical factor please explain the long runners on slant sixes and the long ram intakes on the 413  dual 4 BBL intakes.

Edited by greg g
  • Like 1
Link to comment
Share on other sites

Greg part of the reason could be this.

This is not pressurized fuel injection system.

So yes atomized fuel enters the plenum and is drawn into the intake manifold.

Which 2 cylinders do you think might receive the most or best balance?

If you said cyls 3/4 give yourself a correct mark.

Cyls 1,2 5,6 get there's too obviously but not as effecient as 3 and 4.

The runners on a slant 6 very long and balanced supplying to 6 ports and with a puny 1 bbl very asthmatic.

Different movie altogether compared to a siamesed flathead intake and ports.

I dunno Greg do you think a1 bbl intake supplies fuel to all the cyls in an equal fashion? I sure dont believe so.

I could be off my beliefs but dont think so.

If a center carb feeding 3 siamesed ports were great we would all have 4bbl single carbs for more power and perf as you see a lot on hopped slant 6s..

 

 

Edited by 55 Fargo
Link to comment
Share on other sites

So let's consider dual carbs for single cyinder engines.  Re read, I stipulated that three and four are probably best served and most efficiently provided for.  But if number 1 and 6 are pumping the same amount of air they must by the principles of fluid Dynamics get the same intake charge assuming valve timing and intake valve timing lift and duration are the same.  Is it possible that some fuel falls out of the vapor state sure.  If it's significant where does it go. Does it pool in the intake??  If it does might this not allow the pooled fuel to cause the rear cylinders to run rich under acceleration?  And conversely do the front cylinders run rich while braking??  It's like tire rubber.  We know it wears off our tires and others tires but shouldn't it accumulate at the side of the road?  Other than chunks of truck tires, you don't see rubber laying around.  Where does it go?

Edited by greg g
  • Confused 1
Link to comment
Share on other sites

30 minutes ago, greg g said:

So let's consider dual carbs for single cyinder engines.  Re read, I stipulated that three and four are probably best served and most efficiently provided for.  But if number 1 and 6 are pumping the same amount of air they must by the principles of fluid Dynamics get the same intake charge assuming valve timing and intake valve timing lift and duration are the same.  Is it possible that some fuel falls out of the vapor state sure.  If it's significant where does it go. Does it pool in the intake??  If it does might this not allow the pooled fuel to cause the rear cylinders to run rich under acceleration?  And conversely do the front cylinders run rich while braking??  It's like tire rubber.  We know it wears off our tires and others tires but shouldn't it accumulate at the side of the road?  Other than chunks of truck tires, you don't see rubber laying around.  Where does it go?

That settles it Greg pull off your dual intake and go to a 1 carb setup.

Heck even better get a 2 bbl to 1bbl adapter and a Langdon carb.

Geesh are you the new Devils advocate..lol

Link to comment
Share on other sites

On 2/12/2019 at 9:22 PM, sser2 said:

Exhaust performance 1

Exhaust performance 2

Exhaust performance 3

Just from top of Google search list. Larger exhaust improves performance at high engine speed, especially at speeds approaching top rpm. At low to normal driving speeds, there is no improvement or deterioration. Dynamic performance (acceleration) may suffer. 

 

Now I'd like to see evidence for souped exhaust making difference at normal driving.

I would like to see or hear evidence of a flathead 6 turning 6000 RPM's

  • Haha 1
Link to comment
Share on other sites

53 minutes ago, Don Coatney said:

I would like to see or hear evidence of a flathead 6 turning 6000 RPM's

Well here is 1 turning 5500 revving no load.

But I guess it would take another 500 to impress you.

I suggest you Call George Asche to discuss a 6 k RPM redline possibility. 

 

  • Like 1
Link to comment
Share on other sites

58 minutes ago, 55 Fargo said:

Well here is 1 turning 5500 revving no load.

But I guess it would take another 500 to impress you.

I suggest you Call George Asche to discuss a 6 k RPM redline possibility. 

 

I'm not saying it can or can't but I could snap a Briggs&Stratton to 6k with no load.  It sure seems like this "Velociraptor" struggles a bit to get there....

Edited by Adam H P15 D30
  • Confused 1
Link to comment
Share on other sites

I spoke to George Asche last Friday and he told me about someone he knew many years ago who got a 265 up to 7200 rpm during turns in races.  Stock crank, rods, rod bolts, etc, except the guy had to modify the bearing oiling configuration by cutting grooves in the rod bearing halves and cutting grooves in the main bearing journals (not the main bearings themselves, as they already have grooves, but the main journals).  It had some power boosting mods or else the engine wouldn't rev that high, but the engine was capable of taking those revs repeatedly.  George also tells a story about cruising from Salt Lake City to Los Angeles in 1953, averaging between 4000 and 4500 rpm for 9 hours straight.  Again, there may have been some intake and exhaust mods, but he says it was otherwise stock, and was either a 251 or a 265.  He also had a 265 that he routinely took up to 6000 rpm during races, again with power mods, but stock crank, rods, pistons, etc.  Maybe not proof, as we're not there to see it ourselves, but I tend to believe George.  I've also read about tractor pull competitors using 265s and other Chrysler flatheads and taking them up to 6000 rpm and beyond, with mods of course.

Edited by Matt Wilson
Link to comment
Share on other sites

1 hour ago, Adam H P15 D30 said:

I'm not saying it can or can't but I could snap a Briggs&Stratton to 6k with no load.  It sure seems like this "Velociraptor" struggles a bit to get there....

Well its a race engine and no load.

What kinda redline you gettin?

Better yet Adam how bout a video if your flattie runnin. And not a HF clone engine running to 6 grand.

Edited by 55 Fargo
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Terms of Use