Another tech-type question 90°vs72°?

[davehenrie]

The AIM 5.5L has a 90° V which I am assuming lowers the center of gravity compared to the Judd 5.5L which has a V angle of 72°. So the question is, can the drivers feel the difference between the two engines? Or is it more of an engineering principle with just a tiny performance gap?
dh

[MulsanneMike]

Here's 72 vs 100 degrees using a generic engine. Note block height difference.

http://www.mulsannescorner.com/Vangles.jpg

[diabloA1]

Originally Posted by davehenrie

The AIM 5.5L has a 90° V which I am assuming lowers the center of gravity compared to the Judd 5.5L which has a V angle of 72°. So the question is, can the drivers feel the difference between the two engines? Or is it more of an engineering principle with just a tiny performance gap?
dh

The obviously benefit with going 90° is on the chassis since CG is now lowered. Engine power would be the same, given that all other variables remain constant.

Its a packaging benefit

[GTfour]

Originally Posted by diabloA1

The obviously benefit with going 90° is on the chassis since CG is now lowered. Engine power would be the same, given that all other variables remain constant.

Its a packaging benefit

Yep,so it also makes for a lower enginecover, thus less earodynamic drag.

[gucom]

doesn't it also make the engine wider? For instance with the Audi R15, where they guide air through the car, would this be a disadvantage? Or in a theoretical front-engined car like the Panoz?

[MulsanneMike]

Originally Posted by GTfour

Yep,so it also makes for a lower enginecover, thus less earodynamic drag.

Well given that most contemporary engines are no taller than the monocoque, the aero benefits are minor (consider that the induction bits tuck up behind the roll over structures too). The V angle difference mostly benefits CG.

[1200Datto27]

Are both of these engines 8 cylinders, or is the Judd a 10 cylinder unit?

[MulsanneMike]

Originally Posted by 1200Datto27

Are both of these engines 8 cylinders, or is the Judd a 10 cylinder unit?

AIM engine is simply a 90 degree version of the Judd GV5.5. The AIM is designed and built by Judd.

[1200Datto27]

Interesting that they have gone for the optimal V angle for a V8 (90 degrees) with the V10 engine, I would believe that the AIM would have greater vibrations transmitted through the chassis due to the firing order being out of sync with the crank location.

[chernaudi]

Most current production based V10 road car engines(the Audi/Lambo 5.0/5.2 V10, and the Dodge/Chrysler 8.0-8.4 V10) are 90 degree V10s-because the Audi/Lambo V10 is based off of Audi/VW's 4.2 V8, and the Dodge V10 is based off of the 5.9 liter 360 Magnum V8.

It's all about the crankshaft arrangement and firing order: http://en.wikipedia.org/wiki/V10

[gwyllion]

In the F1 V10 era most teams ran a 90° V angle. Renault even tried a 111° V angle.

BTW Peugeot is a 100° V12.

[davehenrie]

thanks for the info guys.
dh

[knighty]

In F1 this sort of change in engine could be noticed.....but in sports cars its proven to be a waste of time......the 90 degree AIM engine is just the same as the 72 degree customer engine in terms of performance........each bank is only lowered by 9 degrees either side, and considering it all needs to sit behing the mandatory ACO imposed twin roll hoop structure, to notice a change in rear bodywork is real small......for what you lose in height reduction, you gain in width........just look at the performance of the pescarolos.

John Judd had wanted to do a 90 degree engine for years, then AIM came along and financed it for him........in hindsight they were probably better off doing something a bit more adventurous, like a down-sized turbo engine, which is more road relevant, and wll have good parallels with AIM's road car consultancy.

I'm lead to believe the real gains in C of G reduction in a sports car are in the clutch diamater......they need to be of such (big) size as sports car engines are big torquey motors compared to F1.