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1940s cadillac top speed?


Joe Werner

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5 hours ago, Oldtimer 11 said:

The 41 Buick Century of 41 was faster yjan the 42 to 51 models because the dual 2 barrel carbs were not offered after the war.  It would have been too embarassing for GM to have a straight eight that was faster than the Rocket 88 49 Olds V8

 

 No straight eight Centuries built postwar.  

 

  Ben

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54 minutes ago, Matt Harwood said:

Since many of these posts are now 15 years old, here's the proving ground paperwork:

 

1960338933_Testtrackfigures2.thumb.jpg.6

Cool Buick chart Matt !  

 

I was thinking S.C. would be Stomberg carburetor and C.C. would be Carter Carburetor

 

Sidenote:  Next post suggests:  could it be single carb vs compound carb, which is I think how Buick referred to the dual carb set up?

Edited by John_Mereness (see edit history)
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27 minutes ago, billorn said:

 

This makes sense to me. Its comparing 40 to 41 probly to show compound carbs was better.

Except when Idling. Terrible fuel distribution with compound carburetion at Idle. Same with 2X4 on Buick and Chevrolet V-8. Pontiac's with 2X4's didn't have that problem because both carbs had a idle circuit.

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45 minutes ago, bryankazmer said:

could it be single carb vs compound carb, which is I think how Buick referred to the dual carb set up?

Could be !  Cadillac alternated between the Stromberg and Carter - not sure the exact locig as my 60 Special was Stomberg with Automatic Trans. and my Convertible was Carter with Automatic Trans. 

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The chart is definitely referencing single carb (s.c.) versus compound carb (c.c.). They were extolling the fact that the compound carbs not only improved performance, but also fuel economy. I'm a little suspicious of a Limited being able to hit 102 MPH, but I've had mine to an indicated 80 without issues, so maybe there's another 20% in there...

 

47 minutes ago, Pfeil said:

Except when Idling. Terrible fuel distribution with compound carburetion at Idle. Same with 2X4 on Buick and Chevrolet V-8. Pontiac's with 2X4's didn't have that problem because both carbs had a idle circuit.

 

I disagree. Compound carburetion got a bad rep, mostly because of the simultaneous switch to a 10mm spark plug AND the switch from a road draft tube to a primitive type of PCV where crankcase vapors were sucked back into the air cleaner.  The plugs tended to foul because of it, and most people blamed the carburetors as not delivering fuel properly. However, the solution, per a factory TSB, was to block-off the PCV tube and replace the oil filler cap with a vented version and to drill out the spark plug holes for larger plugs--not modifying the carburetors. Properly set up, dual carb Buicks idle quite well. Both of mine are buttery smooth and the '41 Roadmaster I currently have in my inventory also idles quite well once it's off the choke and runs so smoothly and quietly that you have to shift by speed because you can't feel or hear the engine.

 

I will say that dual carb Buicks with Carters tend to idle notably smoother but the Strombergs are easier to tune. Performance is probably equal. I have Strombergs on my cars and prefer them--the Roadmaster with Carters is so smooth and quiet, but my Limited running synchronous (rather than progressive) Strombergs makes such wonderful sounds...

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Looks like the top speed was the dual carb and a 3.6. Lower gears seem to be rpm limited.

 

I've had dual quads on both Pontiac and Chevrolet engines. Usually got over 20 mpg on the road. Best (22 mpg @ 70) was Duals on a 305 with cam and mild porting pushing a 3.07 through a Muncie.  Had progressive linkage with idle circuits' on both but below about 50% ran mainly on rear carb primaries. 700 rpm idle. Jetted way down from stock. (rear primaries were in almost the same location as a two barrel.

 

When running in F/S I was limited to a single 2 bbl. Chev had a very interesting 1 3/8 2bbl for a 454 trailer towing package that with a little tweaking would pull to 6k on a stock appearing 305. Was close to 500 cfm.

 

Got 25 road  mpg out of a 67 Camaro 'vert with 327 and a Rochester FI but that was before catalysts.

 

Bottom line for any engine seeking top speed you need to gear for max torque at or a little below the desired top end. Making any engine breath better will usually raise the torque peak. Does not matter when the engine was built if the bottom end can take it.

Edited by padgett (see edit history)
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On 5/19/2012 at 12:18 PM, Rusty_OToole said:

horsepower required, goes up as the square of speed. 

 

.............. As the CUBE of the speed.

 

1 hour ago, padgett said:

 for any engine seeking top speed you need to gear for max torque at or a little below the desired top end.

 

............... You need to gear for max HORSEPOWER....................

 

Horsepower is an expression of work. Work is a function of time, (e.g. miles per HOUR).Torque is an expression of moment, (e.g. ft/lbs). 

             

                   "Annie Had A Baby, (Can't Work No More)"   -   Hank Ballard, (And the Midnighters)

.                         Cadillac Carl, all torqued out, (Can't hardly work no more).    -   Cadillac Carl 

 

 

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9 hours ago, Matt Harwood said:

The chart is definitely referencing single carb (s.c.) versus compound carb (c.c.). They were extolling the fact that the compound carbs not only improved performance, but also fuel economy. I'm a little suspicious of a Limited being able to hit 102 MPH, but I've had mine to an indicated 80 without issues, so maybe there's another 20% in there...

 

 

I disagree. Compound carburetion got a bad rep, mostly because of the simultaneous switch to a 10mm spark plug AND the switch from a road draft tube to a primitive type of PCV where crankcase vapors were sucked back into the air cleaner.  The plugs tended to foul because of it, and most people blamed the carburetors as not delivering fuel properly. However, the solution, per a factory TSB, was to block-off the PCV tube and replace the oil filler cap with a vented version and to drill out the spark plug holes for larger plugs--not modifying the carburetors. Properly set up, dual carb Buicks idle quite well. Both of mine are buttery smooth and the '41 Roadmaster I currently have in my inventory also idles quite well once it's off the choke and runs so smoothly and quietly that you have to shift by speed because you can't feel or hear the engine.

 

I will say that dual carb Buicks with Carters tend to idle notably smoother but the Strombergs are easier to tune. Performance is probably equal. I have Strombergs on my cars and prefer them--the Roadmaster with Carters is so smooth and quiet, but my Limited running synchronous (rather than progressive) Strombergs makes such wonderful sounds...

 

You might not disagree if I drilled and welded in provisions for eight O2 sensors on each exhaust port to measure the CO/HC. Of course we old timers could also tell by the readings of the spark plugs. Even with one carburetor on a straight eight you can see the difference in spark plug readings from the two outside plugs from the two inside ones.

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All the large Buicks of 41 had an optional compound carb setup avai;able , not just the Century.  It was the carb option that I was refering to not be available after the war.   For the poster who said a lot of 1930s European cars would top 100mph. I would like to say tjat there were a lot of 30s and even some 20s American cars that would do it. That changed when they stopped when they stopped making Duesenbergs, Marmons, Auburns,Cords, Pierce Arrows. and I imagine a lot of 12 cylinder Packards and 12 and 16 cylinder Caddies plus other cars I have forgotten or don't know about.  I learned to drive on a 41 Century with compound carbs, I don't know what had been done to it but in 51 and 52 when we had it , It idled smoothe as silk and was still on of the faster cars on the road.  There is nothing inherently more powerful about a V8 than a straight eight and the straight eight always has better balance and less vibration.

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On 5/18/2012 at 4:47 AM, ralphk said:

So, Rusty, I gather that you are saying that the folks operating the Bonneville Speed Trials do not know how to set up their traps nor how to interpret the readouts. Or are you trying to say that the salt flats are actually a hill.These are the same people at roughly the same place that timed a 57 Chrysler at 171+ 2 way (one run had been in excess of 186 but they had to redo it because a piece of chrome blew off). By the way, my reference to the prewar New Yorkers came from a Highway Patrolman friend of the family complaining that none of their cruisers could come close to catching a New Yorker and that one could easily outrun their spotter plane.

Are you saying the old flathead 323 cu in 135HP straight eight New Yorker, was faster than the new 331cu in, 180HP  Hemi V8? If so, Chrysler sure wasted a lot of money developing the new engine.

I don't remember mentioning Bonneville, or the 57 Chrysler. I don't doubt that a 57 Chrysler 300 with a 400HP+  hemi head 392 cu in V8 made 171MPH on the Bonneville Salt Flats. What this has to do with a pre 1950 Cadillac, or a 51 Chrysler is beyond me.  Besides the vast difference in cars and engines there is a big difference in air resistance between sea level and Bonneville - 4119 feet elevation. And possibly a difference in rolling resistance between wet sand and salt. I know top speed on the sand is about 10% lower than on a hard top road. Also, the Daytona Speed Trials were for strictly stock cars while Bonneville is for hot rodders and hop ups are not only accepted, they are encouraged.

 

My point was that a GENUINE 100MPH, independently timed, for a CERTIFIED stock, unmodified car, would be very rare for any pre 1950 model.

Edited by Rusty_OToole (see edit history)
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In the mid 1990's three of us were heading east on the stretch of RT 490 approaching the entrance to the New York State Thruway. I was driving at 75 MPH. Up ahead on the shoulder of the road was a van with the back doors open and the spare leaning against the side. I pointed at it and said "Check this out, Ed". As we drove past we saw the radar setup and two troopers in the back, gun pointing out.

On to Syracuse unmolested, we must have been doing between 65 and 72.

 

That was with Ed Allen's '41 Model 62 that he had owned since 1964. We turned 40,000 that day.

 

Ed in red and me. Trivia note: Model 62 with running boards and horn button (no horn ring), purchased new by an economics professor at the University of Rochester.

 

In Walter Miller's parking lot.

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WARNING MATH

 

Was a bit of a test. As speed goes up there are a number of forces at work - internal friction of the motor, rolling resistance, drivetrain losses, accessory losses but by far once speeds get higher, aerodynamic drag forces are the most important. The formula I gave, F_d\, =\, \tfrac12\, \rho\, u^2\, c_d\, A, is the formula for the aerodynamic drag of an object in motion through a compressible fluid (air).

 

The drag force (what the engine must overcome) equals 1/2 rho (fudge factor relating to air density and such) times the square of the speed, times the coefficient of drag (how slippery the shape is) times the frontal area of the object (aka CdA).

 

In simplest terms it takes about 3x the power to go 100 mph as 60 just for the extra drag. Not going to go into Tractive Effort.

 

But the bottom line is that to maximise speed you want to gear so that the max speed is at or just above the maximum torque.

 

In the bad old daze torque peaks were pronounced and usually had a quick drop off with a HP (pure math from torque, rpm, and a fudge factor) peak shortly thereafter.

 

Now modern race cars use fractals to estimate real drag, lift, and cooling. General Motors was using six degrees of freedom in computer models in 1970 which made it easy to adapt to over one gee models for a Corvette. Turned out the 68 rear suspension had better camber characteristics that the 69-up or 63-67. $15 item.

 

The biggest difference comes from computer controlled spark plus VVT. A modern DOHC - 4 valve (no hemis need apply) head with VVT and DI can have 90% of the torque peak from about 1800 rpm to 7000 rpm on pump gas. In fact a significant part of the silly horsepowers seen today is from raising the torque peak from 4800 rpm to 6800 rpm.

 

Be glad to go further but first read Sir Harry's "The High Speed Internal Combustion Engine".

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3 hours ago, bryankazmer said:

Agree on the inherent balance.  A straight eight is more susceptible to crankshaft whip, but the better ones had 9 main bearings to address it.  I think the difficult issue is getting uniform flow to all cylinders.  Hence Buick's duals and some aftermarket set ups.

 

Inline-eight engines also aren’t possible to build in a perfectly harmonically balanced configuration, as is possible with a cross-plane V8.

The crankshaft in an inline-eight would be quite long and would be more prone to flexing and/or failing under the increased torque than a shorter crankshaft. This is also true of the camshafts. 9 main bearing Packards can be made to Idle pretty smooth, but they too have a fuel distribution problem as in all straight eights which are the outside cylinders run lean, the inside cylinders run rich and the two middle are just right.

  BTW. the Buick straight eight is only five main bearings, heck my gen3 Chevy inline six has seven main bearings! now that is a inherently balanced and smooth engine which easily passes the quarter test, although as witnessed my dad's 50 Pontiac straight eight had no problem passing that test as well. 

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