6 replies to this topic

[wise.mumu]

This is my first post here. I have been lurking around this forum for sometime now and I know there are a lot of intelligent people in here. So here goes...

This might be a dumb question but how does engine configuration affect its performance?
Let's say we limit the definition of "performance" into:
a. peak HP
b. peak torque
c. HP range (powerband)
d. torque range
e. max rev
f. reliability

Which engine configuration (I4, V4, V6, V12, I6, W12, etc etc) would excel in each category and which would be the best compromise, provided we have a fixed displacement and everything else equal (i.e materials used, cam technology, etc)?

My question might be to broad and I know there wont be a single answer. I just want different insights . this had me wondering eversince I read that post in which regarding engine configurations allowed in F1.. Someone posted that wouldnt it be great if teams are free to choose their engine depending which circuit they are racing (V8 for monaco, V12 for monza, etc)...



sorry if i had to ask... i cant find a "search" button here. hope u can provide time to answer. always been interested in engines...


A bit OT from my own post :
here's one "unconventional" engine i found which might interst you. http://www.revetec.com/ :

[Ray Bell]

The 'search' 'button' is on the right hand end of the line of links at the top of the page, just below Villeneuve's left eye...

Basically, an engine with larger cylinders will have more torque, one with smaller cylinders (and more of them, to give the same capacity) should (mechanical losses not overcoming...) produce more peak power because it will rev higher.

All things being equal, which (of course) you know they're not!

[McGuire]

Originally posted by wise.mumu
This is my first post here. I have been lurking around this forum for sometime now and I know there are a lot of intelligent people in here. So here goes...

This might be a dumb question but how does engine configuration affect its performance?
Let's say we limit the definition of "performance" into:
a. peak HP
b. peak torque
c. HP range (powerband)
d. torque range
e. max rev
f. reliability

Basially, the more cylinders the engine has, the better it will perform in all the above areas. The compromises are in cost and packaging.

[Engineguy]

Roughly...

3.0 LITRE... 2005

cyls...... bore................ stroke................ disp..... valve curtain area..... HP

4 cyl.…. 135.6 mm bore x 51.66 mm stroke… 2984 cc….. 1363 mm^2..…. 542 HP
6 cyl.…. 118.5 mm bore x 45.15 mm stroke… 2988 cc….. 1787 mm^2..…. 711 HP
8 cyl.…. 107.8 mm bore x 41.07 mm stroke… 2999 cc….. 2167 mm^2…... 862 HP
10 cyl…. 100.0 mm bore x 38.10 mm stroke… 2992 cc... 2513 mm^2...... 1000 HP
12 cyl…. 94.1 mm bore x 35.85 mm stroke… 2992 cc….. 2838 mm^2...…. 1129 HP
16 cyl…. 85.5 mm bore x 32.58 mm stroke… 2992 cc….. 3438 mm^2...…. 1368 HP
..

2.4 LITRE... 2006

cyls...... bore................ stroke................ disp..... valve curtain area..... HP

4 cyl…. 126.0 mm bore x 48.01 mm stroke… 2394 cc….. 1267 mm^2…. 504 HP
6 cyl…. 110.1 mm bore x 41.95 mm stroke… 2396 cc….. 1660 mm^2…. 661 HP
8 cyl…. 100.0 mm bore x 38.10 mm stroke… 2394 cc….. 2011 mm^2…. 800 HP
10 cyl…. 92.9 mm bore x 35.39 mm stroke… 2399 cc….. 2335 mm^2…. 929 HP
12 cyl…. 87.4 mm bore x 33.30 mm stroke… 2397 cc….. 2636 mm^2…. 1049 HP
16 cyl…. 79.4 mm bore x 30.25 mm stroke… 2397 cc….. 3193 mm^2…. 1270 HP


From the above, it should be obvious why (from the slow 'em down for safety angle) the number of cylinders was reduced to eight for 2006... simply reducing the V10 displacement to 2.4L would only reduce HP by 71, while going to a 2.4L V8 reduces HP by 200. Not to mention (from the cost angle) the benefit of staying with the already developed 300cc per cylinder package.

[Fat Boy]

Engineguy,

Interesting comparison. Are you holding mean piston speed constant? I'm just curious at the assumptions you made.

If we have a 542 HP 4 cylinder at low RPM vs. a 1368 HP 16 cylinder at high RPM, wouldn't the 4 cylinder be the natural choice? It would make more torque which would accelerate the car at a higher rate. (this is a joke, that no one should get their panties in a bunch over)


Honestly, though, what assumptions did you make?

[Engineguy]

Originally posted by Fat Boy
Engineguy,

Honestly, though, what assumptions did you make?

Stroke 38.1% of bore diameter, per current practice.

Intake valve diameter 40% of bore diameter. Two per cylinder.

Valve curtain area is per mm of lift... I ignored the fact that lift (or at least rate of lift at some points during stroke) may be reduced as the stroke is shortened.

With the assumption that the best mid-2005 3.0L V10 will make 1000 HP (nice round number), I have simply calculated HP for all the others based on their proportionate valve area.

I have ignored potential RPM increases/decreases, which will no doubt cause controversy, but there are factors (friction, combustion efficiency, etc.) that offset... and I did say "Roughly..."

This is probably accurate enough to compare 8 and 12 cylinder alternatives to the base (300cc/cyl) V10 3.0L, and to compare 6 and 10 cylinder alternatives to the base (300cc/cyl) V8 2.4L... the rest are no doubt a little less accurate. It's unlikely anybody would even begin to consider beyond 8 to 12 cylinders for the 3.0L or 6 to 10 cylinders for the 2.4L anyway.

As for the idea of using 2 cylinders less at Monaco... if your V10 3L car is already at minimum weight, your V8 3L car will weigh the same overall, but have a lot less power... a 90mm shorter wheelbase and some increased flexibility in ballasting isn't going to overcome that.

[J. Edlund]

The engine package has also affects on the car if we look outside the performance of the engine.

Some engine configurations will also have certain problems when it comes to vibrations and exhaust tuning for example which could have a negative effect on performance.

Engines with W and flat configurations will also have some difficulties regarding the plumbing from and to the engine.