32 replies to this topic

[GSX-R]

Hello,

35,38,43,51,55 Type : 1, 5, 2, 6, 3, 7, 4, 8
39 type : 1, 6, 2, 7, 3, 8, 4, 5
50,53,54,57 type : 1, 6, 2, 5, 8, 3, 7, 4
59 type 1, 5, 3, 7, 4, 8, 2, 6 (most logical for balancing).

?

Regards

[Halfwitt]

Quite possibly something to do with avoidance of torsional vibrations.

[Greg Locock]

Look at the manifolding as well, both intake and exhaust.

[Fat Boy]

What years were these cars being built? They might have just been trying different combinations to see what worked best. A guy I know at an OEM calls this a 'consumer validated design'.

[BRG]

Originally posted by Fat Boy
What years were these cars being built?

During the 1920s and 30s - so no CAD back then.

Is there nowadays a generally accepted 'right' firing order for a straight eight engine? Or is the engine layout so outmoded that nobody has done any research on it?

[WPT]

Mercedes Benz used a different firing order for the 300SLR than for the W-196 because of the expected lower average RPM in the sports racer. WPT

[McGuire]

Welllll...first, there is one more than one way to phase the throws on a straight-eight crankshaft.

.... also, on some Alfas the firing order was 12345678. Can anyone guess how this incredible feat was accomplished.

[McGuire]

Originally posted by BRG
During the 1920s and 30s - so no CAD back then.

Is there nowadays a generally accepted 'right' firing order for a straight eight engine? Or is the engine layout so outmoded that nobody has done any research on it?

I would say so. In the USA the standard for straight eights settled upon the Packard-style crankshaft and the firing order 16258374. Packard, Buick, Chrysler, Hudson, Pontiac, Olds, Studebaker... just about everyone. I believe the only holdout was Hupp.

[Fat Boy]

Originally posted by McGuire
on some Alfas the firing order was 12345678. Can anyone guess how this incredible feat was accomplished.

Uhhhhmmm. Poorly?

[Greg Locock]

"Is there nowadays a generally accepted 'right' firing order for a straight eight engine?"

There's no single 'best' firing order for a straight six, never mind an I8.

It is a compromise between how your intake and exhaust headers are arranged, the desired operating speed of the engine, the crankshaft resonances, and your priorities when tuning the engine, and the durability, and how much time/money you are willing to spend sorting out any problems that result, and the layout of the crank and and and.

I really enjoyed my shortish stint working on engine design, maybe my next lateral career move will be to design the last gasp of the automotive IC engine.

[McGuire]

I guess it depends upon what one means by "generally accepted 'right' firing order." Not that it's the only way to do it by any means, but you will find that by far the overwhelming majority of the inline sixes in the world have fired 153624. More or less Standard Practice if you will. Just as "standard" firing order for straight 8's was 16258374.

[McGuire]

Originally posted by Fat Boy


Uhhhhmmm. Poorly?

No, it was simple. Jano liked to number the cylinders on his engines in the order in which they fired instead of where they were located in the block, that's all.

[Fat Boy]

Originally posted by McGuire


No, it was simple. Jano liked to number the cylinders on his engines in the order in which they fired instead of where they were located in the block, that's all.

Changing the firing order must have been a bitch. You'd have to recast the cylinders in different order!

(yes, that was my attempt at humor)

[McGuire]

Ing. Gioacchino Columbo was quite a card as well. Allegedly, his built-up crank in the Bugatti T251 (the transverse midships straight 8 car of ca.1956, last Bug GP racer ever) was designed so that it could be knocked apart to screw around with the phasing and firing order.

[McGuire]

One consideration in Bugatti firing orders... though they were mainly straight 8's, they were of remarkably different construction one to another. For example, the T35 GP engine used five main bearings (ball/roller) while the T35A sportsman version ran on three plain bearings. Some Bugs ran one-piece cranks while others used built-up cranks with one-piece rods.

...perhaps the smoothest and silkiest automotive engines ever (IMHO) were the Packard Senior Eights. These fired 16258374 and the crank was phased such that it was essentially an inline four in the middle with half a four on each end disposed at opposite right angles to the middle four. You really can idle one of these engines down to around 200 rpm and balance a nickel on the cylinder head...from the driver's seat you CANNOT tell if it is running. What a beautiful thing. Ran in nine main bearings... very rigid and well-supported but really loooong. TV's would be a big problem if you tried to turn such a thing at any real speed.

[Wuzak]

Originally posted by McGuire
Ing. Gioacchino Columbo was quite a card as well. Allegedly, his built-up crank in the Bugatti T251 (the transverse midships straight 8 car of ca.1956, last Bug GP racer ever) was designed so that it could be knocked apart to screw around with the phasing and firing order.

Wasn't that essentially two four cylinder engines, with the power take off from the centre of the crankshaft, in a T-drive arrngement (transverse engine, longitudinal gearbox)?

[McGuire]

Originally posted by Wuzak


Wasn't that essentially two four cylinder engines, with the power take off from the centre of the crankshaft, in a T-drive arrngement (transverse engine, longitudinal gearbox)?

Yes, exactly so. The Alfa 8C and Mercedes W196 I8's also took drive off the center of the crank to control torsional vibrations.

[m9a3r5i7o2n]

Bugatti firing orders.
Never having much appreciation for Bugatti and his eccentricities I believe he just put the firing order on the engine as it fired, several engines have done this I believe that Sunbeam did this on some of the old side valve V-12s. I’ll have to look it up one of these days.

In my old MoToR AUTO REPAIR MANUAL all American cars from 1935 to 1948 fired 1-6-2-5-8-3-7-4. This includes Buick, LaSalle, Chrysler, Nash, Packard, Pontiac and Studebaker.

M.L. Anderson

[robert dick]

Concerning the Grand Prix cars, type 35 to 51 - from Hugh Conway's book : "Grand Prix Bugatti" :
"The arrangement of throws is that of two four cylinder cranks at 90 degrees, but the four cylinder units are themselves unusual in that the throws are arranged 1,3/2,4 in place of the usual 1,4/2,3 to give a firing order 1.5.2.6.3.7.4.8. A few late 51-55 engines had 1,4/2,3 cranks and the normal firing order of 1.5.3.7.4.8.2.6."

- from Laurence Pomeroy's book : "The Grand Prix Car" :
"Both the firing order and the layout of the crankshaft were unique amongst straight-eight engines. The latter goes 1, 5, 2, 6, 3, 7, 4, 8, i. e. taking each block of cylinders separately the firing sequence is 1, 2, 3, 4 on the front four bank, and 5, 6, 7, 8 on the back four. This was coupled with a singular crank arrangement. In this layout the engine is well balanced except for a couple between the front and back halves of the shaft, which imposes severe loads on the centre bearing."

Concerning the straight-eights with three main bearings, type 30, 35A and 38 - from "The Automobile Engineer", July 1927, E. W. Sisman : "The Straight-Eight Engine" :
"Type IV (meaning two four-cylinder cranks at 90 degrees and the throws at 1,3/2,4) is the arrangement adopted on the Bugatti and Elizalde. The primary and secondary forces are both in balance, but owing to the unsymmetrical spacing of the cranks there are both primary and secondary rocking couples. It is therefore difficult to see any apparent reason for adopting this type especially in the case of the Bugatti. Here there are only three main bearings, and the loading of the centre bearing must be exceptionally severe."

[GSX-R]

Thank you for reporting the last comments. It's quite difficult to find "official" comments from Bugatti to explain those arrangements.

[Ray Bell]

Just being an interloper in this discussion...

There is a thread in TNF about Niel Allen trying a flat plane crank in his F5000 McLaren... this is how Graham Howard recalls it:

Originally posted by Graham Howard
Peter Molloy told me the story, and it was to illustrate the effects of a flat-plane crankshaft. Molloy made this crank, using one of Merv Waggott's lathes, and it was used for the first time at Bathurst, where it not only loosened rivets in the tub but also shook off the mirrors, and new engine mounts had to be made between practice and the race.

Molloy later decided the balance was wrong and added extra weights, but later again decided a conventional 90-degree crank was just as good. At the time, however, the team felt the flat-plane engine had more mid-range torque. Niel Allen described the flat-plane vibration as "very high, intense; not a shake but something that went right through your backbone."

There was an answer, however, beyond balancing. I discovered this while writing about the M10Bs in Australia:

From Fast that's Past, Motor Racing Australia
But Allen wasn’t driving it to its full potential, and with good reason. Despite adding extra counterweighting to the crank, Molloy couldn’t get rid of the high frequency vibrations, Allen feeling them through his bones and the tub of the McLaren was having rivets pop in sympathy with Allen’s pain.

The lap record of 2:09.7 could have been even faster, though Allen’s description to Molloy of how he aviated over the second hump on Conrod Straight created shivers down spines.

Later the flat plane crank would return, but without the worst of the vibrations. "Roy Woods put us right on that," Kevin Bartlett told us, "you had to change the firing order, Crower made a cam that enabled us to do that."

So the learning goes on...

[m9a3r5i7o2n]

After reading Ray Bell’s message I find it difficult to believe that a group of people can’t find the firing order of a 180 degree crank V-8 all of them that I have found are the same only the cylinder numbering system is different. Using the Chevrolet V-8 numbering system it is identical to the 1930-21-32 Oakland-Pontiac V-8, 1-4-5-2-7-6-3-8 which is the first V-8 I know that used the numbering system that Cadillac and Chrysler Corp. and others use to this day.
Also in Kalb’s formula about balancing the V-8 crank he states that it needs 8 (not 6) counterweights for the V-8 crank on both the 180 and the 90 degree cranks. This is somewhat hidden in a small asterisk after the W=C entry. It is also in Taylor’s book.
Wolseley did this in 1917-18 on the Hispano-Suiza 718 cubic inch aircraft engine.
M. L. Anderson

[McGuire]

Originally posted by m9a3r5i7o2n
In my old MoToR AUTO REPAIR MANUAL all American cars from 1935 to 1948 fired 1-6-2-5-8-3-7-4. This includes Buick, LaSalle, Chrysler, Nash, Packard, Pontiac and Studebaker.

Yep...except for Hupmobile which fired 14738526. They were contrary about most everything. Used some non-standard thread pitches too, like 3/8-20.

[McGuire]

Personally I think the flat crank conversion is a push in a stockblock pushrod V8. Not worth all the effort.

[Fat Boy]

Originally posted by McGuire
Personally I think the flat crank conversion is a push in a stockblock pushrod V8. Not worth all the effort.

Maybe not in terms of power, but in terms of sound, it's time well spent.

[Ray Bell]

Ah yes... that's so very true!

Marion, I only passed on what Kevin told me, and I have no reason to doubt him.

[m9a3r5i7o2n]

About the nonuse of the 180 degree crankshaft, NASCAR probably has a rule in their books stating no 180 degree crankshafts are allowed. This is why some of the weird exhaust pipes, at least weird to me.
It is my belief that if the rule were changed at the end of the season that next year all the cars would have 180 degree crankshafts. One must remember that would allow a simplified exhaust system than the one now used. How long do the crankshafts last anyway?
I’m sure that the NASCAR mechanics aren’t stupid about exhaust tuning. And that is true even if it only gave them 50 horsepower. Also I am not sure that crankshaft life would be changed that much anyway. Just the drivers hands getting numb from the engines being bolted to the frame, would they not?

I am at this time getting several sketches drawn that will show the difference between the four cylinder engine vertical shake and the V-8 horizontal shake in a 301 cubic inch V-8 and a four cylinder vertical four @ 150 cubic inch. using the same stroke etc.
M. L. Anderson

[m9a3r5i7o2n]

McGuire; Do you happen to have the cylinder numbering system on that engine of the Hupmobile
as I believe I have the thing in hand but only if the numbering is different. The same people that worked at Hup must also have worked on the first Cord V-8.
M. L. Anderson

[Ray Bell]

Surely it was an inline eight?

So it either counted from the front to the back, or followed the French system of counting from the back to the front.

[m9a3r5i7o2n]

Ray; Just how they did it is somewhat as you state. It is the same firing pattern as all the other American straight eight car engines. However for some inexplicable reason it only works if it is numbered front to back but fires back to front??? I am, I believe, trying to cut the Gordian Knot with a dull sword.
M.L. Anderson

[McGuire]

Originally posted by m9a3r5i7o2n
McGuire; Do you happen to have the cylinder numbering system on that engine of the Hupmobile
as I believe I have the thing in hand but only if the numbering is different. The same people that worked at Hup must also have worked on the first Cord V-8.
M. L. Anderson

One through eight front to back.

[m9a3r5i7o2n]

Some people make their own troubles. The engines fires actually back to front. If you flip journals 3,6,4 & 5 it works perfectly.
As I previously stated these guys must have worked on the first Cord V-8.

M.L. Anderson

[VAR1016]

Yet another very interesting thread - although I do not have the brains - or at least the training - to follow much of the logic.

Amongst many of the "armchair" projects (there were some successful real ones!) dreamed up by a fellow Lancia Fulvia enthusiast and I, was one prompted by listening to the glorious sound of a Type 35B Bugatti at some event.

At the time I understood that the Bugatti's straight-8 comprised two conventional four-cylinder engines joined together at 90 degrees. We quite fancied joining two 1300cc Lancia Fulvia engines end to end to make a 2.6-litre 8. Though called a V4, the Fulvia is a staggered straight four with offset crankpins, so we would have made a sort of V/straight 8.

We often wondered if it would work. We wondered what the firing order would have to be for two four cylinder engines joined in this way and assumed that it would be 1.5.3.7.4.8.2.6. as Robert Dick mentioned above for some of the Bugattis. Obviously the camshafts would have had to be different.

However his post suggests that the result would not have had that T35 sound - perhaps more like a T51 - not bad anyway for anyone who has heard Charles Dean in action.

PdeRL