15 replies to this topic

[Greg Locock]

Anybody know what the firing order, preferably on the Ferrari, is?

And if you do please specify how you are counting the cylinders, I just had a very stupid conversation with someone because GM guys number their cylinders in a different way to Ford!

FWIW a Viper is 1 10-9 4-3 6-5 8-7 2-. with, I think the hyphen representing 54 degree separation, the others being 90. I'd guess they are just counting down the cylinders from the front, ie odds are left, evens right or vice versa.

That is quite a 'bad' firing order as far as charge robbing goes, 1 3 7 9 5 is more conventional.

[jpf]

Marion Andersen kind of initiated and sustained a series of threads about firing orders in the past couple years, which he illustrated, annotated, etc. etc. Search around, read them through and you won't be disappointed.

[McGuire]

According to Peter Wright's book the 2000 Ferrari was

1-10-5-6-2-9-3-8-4-7

RH front cylinder is #1; LH rear cylinder is #6

like so:

right bank 1 2 3 4 5

left bank 10 9 8 7 6


Wright also includes this quote from Paolo Martinelli:

"We look at a lot of alternative firing orders, mainly to control vibration, to avoid peaks in the area of the revs where the engine spends 90% of its life and full throttle is used. There are of course fluid dynamic effects, both in the intake and exhaust, but vibration is the big issue."

[Greg Locock]

Thanks very much. The big reason to get the firing order right is usually the excitation of the crank torsional and bending resonances. That's the same firing order as the Viper, notice that the rear 3 pairs fire consecutively.

[McGuire]

Originally posted by Greg Locock
Thanks very much. The big reason to get the firing order right is usually the excitation of the crank torsional and bending resonances. That's the same firing order as the Viper, notice that the rear 3 pairs fire consecutively.

Yep. Also, while the photos of the Ferrari 049 don't explicitly reveal them, some of the views seem to suggest the presence of pendulum dampers in the gear drives. It is interesting to me that the engine builders seem to do whatever they like with bank angles and crank phasing with these engines, yet there is constant talk of struggling to manage the vibration issues. It does seem that for now they have all settled at around 90 degree bank angles when 72 seems more practical from all angles save packaging.

The Viper V10 is not a very smooth engine by passenger car standards but the rest of the car is so crude and raw I guess it doesn't matter. The Ferrari 308 V8 series used a flat crank but it really wasn't all that noticeable, perhaps due to the transverse installation (horizontal engine shake is then displaced longitudinally in the chassis). I would like to sample the TVR with its flat crank but they are rare bears here in the USA.

[marion5drsn]

http://forums.atlasf...8&highlight=V10

EDIT- March 31-2004 Right double click below!

http://trellixff1.bu...&target=tlx_new

[Kalle_hopp]

The pictures in the second thread seems to be gone.

[Wuzak]

Originally posted by McGuire

The Ferrari 308 V8 series used a flat crank but it really wasn't all that noticeable, perhaps due to the transverse installation (horizontal engine shake is then displaced longitudinally in the chassis). I would like to sample the TVR with its flat crank but they are rare bears here in the USA.

The Ferrari 355/360 series both have flat plane cranks (I guess the 348 too), and have the engine mounted longitudinally.

The TVR also has the unusual bank angle of 75°.....

[desmo]

I'm quite impressed that Wright was able to get the FO for the Ferrari. Even usually very helpful sources I spoke with would go all quiet when the subject of FOs arose. One Cossie engineer even said that FOs "aren't fixed". Bank angles, crankshaft geometries, and FOs are all apparently useful for addressing critical crank TV issues.

[McGuire]

Originally posted by desmo
I'm quite impressed that Wright was able to get the FO for the Ferrari. Even usually very helpful sources I spoke with would go all quiet when the subject of FOs arose. One Cossie engineer even said that FOs "aren't fixed". Bank angles, crankshaft geometries, and FOs are all apparently useful for addressing critical crank TV issues.

Well, it is four-year old info; for all we know the firing order has changed multiple times since then. As you say and and as Martinelli confirms, it would seem they tailor firing order to suit specific characteristics along the development curve. For example, perhaps the possible use of a stiffer crank and/or heavier recip assembly to suit the one-engine rule might take them into a resonant period which requires adjustment. I don't know that at all, just offering one path of speculation.

[marion5drsn]

Firing pattern for Dodge V-10. Same as Ford V-10 except that Ford uses the DIN standard for numbering the cylinders. This is the same as the one I put up about two years ago.

72 DEGREE BLOCK

http://trellixff1.bu...&target=tlx_new

90 DEGREE BLOCK

http://trellixff1.bu...&target=tlx_new

108 DEGREE BLOCK

http://trellixff1.bu..._edit_page.html

126 DEGREE BLOCK

http://home.earthlin...ttern126deg.jpg

144 DEGREE BLOCK

http://home.earthlin...ttern144deg.jpg

162 DEGREE BLOCK

http://home.earthlin...ttern162deg.jpg

M.L. Anderson

[marion5drsn]

In regards to the V-10 firing orders and firing patterns I have gone thru many different crankshaft layouts of which I can find only 24. This is obviously the main thing that determines the firing order and firing patterns of any engine. The amount of usable ones, firing patterns, would require an enormous amount of man-hours to assemble unless someone has made a computer program to reduce the total to an accurate and nonduplicating printout.
At first I tried this but about halfway thru I found that I was going to wind up with only about 60 instead of the 120 in a formula I used on my pocket calculator. For this reason I have ceased to make out new firing orders, as I don’t know if I am just running into a brick wall.

The amount of machining effort to change a crankshaft and fully machine 24 completely different crankshafts from a solid billet would be, I believe, completely impractical even for wasteful outfits as F-1! Every different crankshaft would require a complete set of four camshafts per engine, 96 total, and who knows what else to even test on the dynamometer.

This brings us to the point of, “Are the spokespeople of F-1 just trying to throw up a smoke screen for the on looking public?
Also if Ford and Chrysler both use the same Firing Pattern we might take a good look at that. I have large doubts that they wouldn’t make a lot of Engineering effort to stay away from every vibration they could find on a 90-degree block V-10. Also how do they know the vibration starts in the crankshaft? There are a lot of other places it might start, camshafts, pumps etc. If the engine runs 750 kilometers do they really care? At this point with the reliability of the Ferrari how much effort do you think that they would put into a program that would result in a minuscule gain in horsepower and reliability? It would behoove them to put more effort into their wind tunnel program than into a program that very well might be a dead end!
The only thing that might be of significant consideration is the placement of a vibration damper to make a large difference and it had to be placed in the center main bearing or some other place of extreme difficulty.
M. L. Anderson

[Greg Locock]

1) How do we know where the vibration originates?

We measure the resonances in the block, the crank, the conrods, etc. We build finite element models, and apply the correct forcing to each piston, in sequence. This gives an estimate of the torsional and bending vibration in the crank, at each speed. We measure the TVs and the bending vibrations in the crank, and use this to correlate the model.

This stuff was well known, and done, even in WW2, there is a beautiful book on Torsional Vibration by Kerr-Wilson. showing this. It was very important then as aircraft crankshafts are long, propellers have high inertias, and the reduction gearbox between the two is mission critical.

Once you know the frequency and amplitude of the TVs and the bending modes you can start to develop and tune a crank nose damper (for the first mode the crank nose is always antinodal, so it is the best place to put a damper. Also it is the most practical!)

Once you are familiar with the sound of an engine you can actually tune these things by ear (BTDT) but it is easier if you measure the vibrations.

On a running engine we use spectograms to identify which component is vibrating. There are sources of confusion, but it does allow us to narrow the possibilities.

I'm not sure that they would necessarily worry too much about the durability effects of this, but to give an example, the LT5 engine on the Corvette would destroy its oil pumps very quickly (<<1 hour) until it was fitted with a crank nose bending damper. Buy an old Corvette! It's got my parts on!


2) Number of combinations

Assuming we always fire number 1 first you have 9! (9*8*7*6*5*4*3*2) combinations.

We know in our hearts (well, challenge that!) we are always going to fire alternate banks, with the left bank always leading, say, so that only leaves 4!, 24, which is a lot more reasonable. Note that some of these are just mirror images of some of the others, eg 12345 is effectively the same as 15432 as far as TVs etc go. So numbering each pair of cylinders from the nose we get (with first sight comments for a few of them)

12345 Too silly
12354 too many consecutive impulses near crank nose
12435 OK
12453 OK
12534
12543 4312 is too structured

13245
13254 quite like this
13425
13452
13524
13542

14235
14253 quite like this
14325
14352
14523
14532

15234
15243 quite like this
15324
15342
15423
15432

OK, so I was bored!

[marion5drsn]

V-10 FERRARI/DODGE FIRING PATTERN

http://home.earthlin...firingorder.jpg


Quote from McGuire
According to Peter Wright's book the 2000 Ferrari was
1-10-5-6-2-9-3-8-4-7
RH front cylinder is #1; LH rear cylinder is #6
like so:
right bank #1 2 3 4 5
left bank 10 9 8 7 6

If one wants to confuse the firing orders and firing patterns to the average layman this numbering system is likely to do it!
The only one even close to being worse is the D.I.N. system. Of course that one was made under the Nazi/Hitler regime. Also someone mentioned that possibly they couldn’t count the conrods when the engine was upside down. Most German engines were built inverted in aircraft, that should have helped but apparently did not. Maybe the engines were built with fork and blade rods?
Oakland/Pontiac V-8 got it right about 1930.
Maybe it is a wonder that the Italians got the bicycle pedals correct!

M. L. Anderson

[marion5drsn]

After reading Gregs mention of the mirror image of the 24 patterns of the cranks I decided to make the 24 paper cranks and see it there were 24. sure enought there are 24 with the 12 mirror duplicates. I then made 12 firing patterns and will try to get them in here somewhere. Greg is right it is boring. The same thing over and over again! M.L. Anderson :yawn:

http://home.earthlin...ringpattern.jpg


http://home.earthlin...ingpattern1.jpg

http://home.earthlin...ingpattern2.jpg

http://home.earthlin...ingpattern3.jpg

http://home.earthlin...ingpattern4.jpg

http://home.earthlin...ingpattern5.jpg

http://home.earthlin...ingpattern6.jpg

http://home.earthlin...inhpattern7.jpg

http://home.earthlin...ingpattern8.jpg

http://home.earthlin...ingpattern9.jpg

http://home.earthlin...ngpattern10.jpg

http://home.earthlin...ngpattern11.jpg

http://home.earthlin...ngpattern12.jpg

[Greg Locock]

Thansk for posting those. In parctice you can eliminate some bad ones, then it is just a case of machining parts up and seeing which works best. For instance, for an I6, Toyota use a completely diferent firing order than we do. We've tried theirs, it sounds rubbish. So we have the option of redesigning our intake and exhaust runners, and the camshaft, and the crank (?) or leaving well alone.