FAO: Puma Racing - Ports

[poppopbangbang]

I thought you would like to see these.







Pretty hey

[Pumaracing]

Holy huge plenums Batman. Unless it's a trick of the camera angle that's some honking great port collector on the intake side. To pulse tune the inlet tract to a very short length perhaps? I can't see it being necessary for flow.

Exhaust valves look as big as the inlets. Now that's a surprise. Is this a N/A engine or a turbo?

Valve seats again look extraordinarily conventional and much as I'd cut them so that's reassuring. There's so much nonsense about weird seat profiles in yank V8 land you never know what to believe.

Combustion chamber is very intricate. Why the cutouts at the sides?

[poppopbangbang]

Pumaracing said:

Holy huge plenums Batman. Unless it's a trick of the camera angle that's some honking great port collector on the intake side. To pulse tune the inlet tract to a very short length perhaps? I can't see it being necessary for flow.

Spot on, the Fondmetal V10s ran an extremely short trumpet and compact throttle body. The height from the top of the port to the top of the trumpet is only 50mm'ish.

Pumaracing said:

Exhaust valves look as big as the inlets. Now that's a surprise. Is this a N/A engine or a turbo?

NA - circa 2000 V10.

Pumaracing said:

Valve seats again look extraordinarily conventional and much as I'd cut them so that's reassuring. There's so much nonsense about weird seat profiles in yank V8 land you never know what to believe.

I've always been confused about all this talk about valve seat profiles, huge money CNC cutters etc. etc. to achieve crazy profiles when our stuff has always been like this i.e. absolutely conventional LOL

Pumaracing said:

Combustion chamber is very intricate. Why the cutouts at the sides?

I honestly don't know for sure as we're never lucky enough to recieve technical engine data. We think it is to promote mixing by providing a directed exit path from the squish area. There are usualy unusual things like this going on in this era of engines where a lot of work was done to promote burn speed etc. to ensure the most gas generation possible in the shortest time to increase load on the crown.

[Pumaracing]

The thing about seat profiles is it's like some sort of religion. If you don't do as I say you'll go to hell and burn for eternity and never be able to build an engine that can produce enough torque to pull the skin off a rice pudding. 45 degree seats are for wkers. 55 degrees is where it's at for clever clogs.

Now of course we can all laugh at people who still use 60 degree bottom cuts. Oh the inhumanity. You fools. Why have you wasted your lives thusly on such nonsense? But when all's said and done most of this is common sense. You want seat angles that best split the difference between the angle the airflow comes down the port at and where it then has to go in the chamber.

But we all worry about whether there's magic secrets we never got to find out. It's human nature. Happily you seem to be telling us that Occam's Razor is still a very viable modus operandi.

[Rwdfords]

poppopbangbang said:

Pumaracing said:

Combustion chamber is very intricate. Why the cutouts at the sides?

I honestly don't know for sure as we're never lucky enough to receive technical engine data. We think it is to promote mixing by providing a directed exit path from the squish area. There are usually unusual things like this going on in this era of engines where a lot of work was done to promote burn speed etc. to ensure the most gas generation possible in the shortest time to increase load on the crown.

That is what I was also thinking, most likely grooves to promote mixture motion around TDC and increase burn speed, the faster and more complete the ignition burn the more power is made especially with high compression and high rpm engines, most of the power is generated in the first 45* ATDC, beyond 90* ATDC there is a lot less power to be had due to the high expansion ratio lowering cylinder pressures

I wonder what kind of static compression ratio and DCR these engines were running along with what maximum advance at and beyond peak power, must be something like 40 to 45* at such high rpm's

[99hjhm]

Pumaracing said:

The thing about seat profiles is it's like some sort of religion. If you don't do as I say you'll go to hell and burn for eternity and never be able to build an engine that can produce enough torque to pull the skin off a rice pudding. 45 degree seats are for wkers. 55 degrees is where it's at for clever clogs.

Now of course we can all laugh at people who still use 60 degree bottom cuts. Oh the inhumanity. You fools. Why have you wasted your lives thusly on such nonsense? But when all's said and done most of this is common sense. You want seat angles that best split the difference between the angle the airflow comes down the port at and where it then has to go in the chamber.

But we all worry about whether there's magic secrets we never got to find out. It's human nature. Happily you seem to be telling us that Occam's Razor is still a very viable modus operandi.

Remember to you need a 15 angle cutter for exhaust seats. lol

[Pumaracing]

poppopbangbang said:

Pretty hey

Just what I was thinking when I walked the dog past the sheep pens at the neighbouring farm yesterday. Some of those little vixens are drop dead sexy. Doesn't half scalp your shins when you finally get their back legs in your wellies though.

[poppopbangbang]

Pumaracing said:

Just what I was thinking when I walked the dog past the sheep pens at the neighbouring farm yesterday. Some of those little vixens are drop dead sexy. Doesn't half scalp your shins when you finally get their back legs in your wellies though.

My Welsh engineer reports that the trick is to take them to the edge of a cliff, they push back more....

[Boosted LS1]

poppopbangbang said:

My Welsh engineer reports that the trick is to take them to the edge of a cliff, they push back more....

I'll have to try that with my girlfriend sometime. Thing is, how do I get her feet in my wellies? ;-)

[Auntieroll]

Don't bother with wellies, use Tywraps.

Edited by Auntieroll on Tuesday 15th April 22:16

[226bhp]

Boosted LS1 said:

poppopbangbang said:

My Welsh engineer reports that the trick is to take them to the edge of a cliff, they push back more....

I'll have to try that with my girlfriend sometime. Thing is, how do I get her feet in my wellies? ;-)

Get some waders, she'll love the feel of the damp rubber.