8 replies to this topic

[hydra]

Hey all,

I was wondering if any of you knew much about the finer details of F1 (or any all-out NA race engine) port design; such as throat diameter/valve diameter ratios, valve seat angles, valve "tulip" angle and average port velocities.

Assuming a bore of 99mm and a stroke of 39mm, this gives us valve diameters of 38.5mm and 31.5mm, give or take 0.5mm, from what I understand valve lifts are in the region of 16-17mm which gives us L/D ratios of 0.41 for the intake and 0.52 for the exhaust, almost exactly in line with maximum figures I've heard from an experienced race engine builder. Check this most useful link out for more info:

http://www.eng-tips....ewpid=71&page=2

Now the question is, how do we go about maximizing high-lift flow coefficients for the ports? I would imagine that swirl and low-lift flow are of secondary importance in an F1 engine and that we would want as downdraught a port as possible, I also know that an average intake velocity of 320-350 fps is close to ideal at max power rpms... I leave it to you guys to take it from there...

[Halfwitt]

Where did you get those valve sizes from? I'd suggest that you could get bigger ones in a bore of that size.

[Chevy II Nova]

I concur that those valves sound a little on the small side, though it would in the end depend on horsepower numbers.

[hydra]

Well, I assumed an intake valve diameter/bore ratio of 0.39-0.40 which is in the ballpark for a race engine... Ok lets assume a 39mm intake and a 32mm exhaust, which should flow well enough for over 950bhp... That's besides the point though, I'm more interested in the port radii, taper, valve seat angles, and other esoteric bits and pieces relating to port design for an all-out race engine... Ideas anyone?

[J. Edlund]

Valves, intake approx 1/3 of bore area, exhaust approx 1/5 of bore area, this is related to the seat inner diameter (Ilmor).

Ferrar 049 engine
Bore x stroke: 96.0 x 41.4 mm
Intake: 40.4 mm, 15,5 mm lift
Exhaust: 33 mm, 14.1 mm lift

Asiatech engine from 2001
Bore x stroke: 91.0 x 46.1 mm
Intake: 40 mm, unknown lift
Exhaust: 30 mm, unknown lift
mean intake gas velocity at peak power: 64,16 m/s

[richdubbya]

Since ive never seen the inside of any f-1 engine, this is all derived from logic and speculation, but i

would be surprised if it wasnt close. Using Edlunds figures, valve curtain area is over 150% of

valve area which would suggest a very high (more vertical and straight port, compromised only by

packaging and valve length) with very steep valve seat angles, tuliped valve, no throat and

mimimal radii (straighter/not smaller radius) all of which would maximize high valve lift flows. All of

which are just the reverse of what you need in a dog legged camshaft controlled port. I would

guess lots of port taper resulting in shorter runners for packaging. This makes sense as low lift

flows are much less important (can even be detrimental) with the very fast opening and closing of

the valves. Now someone that really knows can tell me how wrong i am. lol

[hydra]

So the idea is to minimize port/valve angle inclination, keeping the port straight for as long as possible, and kinking it slightly at the end, thereby maximizing high-lift flow? How low can we go on the short turn radius?

On a slightly different note, what are the largest (vertical) valves we can squeeze in a cylinder bore for a 4V engine? To rephrase the question, what's the closest we can squeeze the intake and exhaust valves together? According to Taylor, we're looking at 0.33B for the intakes, and 0.29B for the exhausts, where B= bore diameter. Intake valve spacing = 0.12B and exhaust valve spacing = 0.133B, with another 0.12B between the intakes and exhausts, leaving valve-bore spacing at 0.03b.

I am of the opinion that we could do quite a bit better than that, I'm thinking we could cut valve spacing to roughly half of that, and end up with an intake of 0.38B and an exhaust of 0.285B again, with VERTICAL valves, or is that being too optimistic, especially when you consider that the exhausts are recessed to form the combustion chamber, whereas the intakes are flush?

[12.9:1]

hydra

I believe I heard Steve Matchett (speed tv) comment on the Mercedes engine failures at the Euro GP, that his sources had mentioned dropped vale-seats as a cause.
As might well be expected from your suggestion.

[richdubbya]

So the idea is to minimize port/valve angle inclination, keeping the port straight for as long as possible, and kinking it slightly at the end, thereby maximizing high-lift flow? How low can we go on the short turn radius?


i dont think i was clear, when i said straighter more vertical ports I meant to the valve seat not necessarily less valve angle inclination. The ports would be straight from the valve seat upwards as far as possible, depending on valve length and packaging for the valve accuation. There would not be a "short turn radius" as normally defined in dog leg ports. Imagine a port you could slide 1/2 of a bananna thru with out making bananna pudding.


I'm not an engineer but thru experience ive found that the limit on exhaust spacing is the burning of the combustion chamber, at least with the materials i have to work with.