308 V12 conversion begins

I never considered that but dont forget the 0sdfgwek weffapo PO A and then she'll be perfect.

 

Mark,

I knew my, "Rossa Subscribed," decoder ring would come in handy someday.
Free with a Rossa Subscription...!
(thanks Rob.)

Edwardo
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Yeah, but what about a slide throttle set up?

 

I do understand its all about making money, and giving up your secrets will make you none. But a great many people have shared valuable data to push the technological envelope of aviation forward, many without a dime of compensation, just a love of things aeronautical and a desire to see it happen, and if they hadnt we would probably still be in the 1930's. Seriously though, aircraft like the Concorde would never have materialsed had so many individuals all kept thier secrets.

In fact I would argue that if there was a greater sharing of knowledge regarding port shape and design, if it wasnt so secretive and voodoo voodoo, porting guys would have more work than they knew what to do with. And if they didnt have to stand there for 40 hours trying to learn as they go they would make even more.

 

But at least I really did post something!

Yes, it is way far above my head, but I sure am enjoying trying to understand! Keep up the geek-speak!

Shiny Side Up!
Bill

 

You should see the POS at the local airport. Airmchair nutcase/aerodynamicist riveted and bondoed strange leading edge affairs all along the front of his wings. Looks like some kid took paper mache to it. Thing will be a lawn dart if he ever finishes it.

 

No clue. I think he's got it down as an experimental.

One thing is for sure...he'll never be able to sell it.

 

It seems that in the US you can do quite a lot in the Experimental category, unlike us in Europe where even the slightest modification needs mountains of stress analysis and paperwork. This is even on homebuilt aircraft certified to the less stringent requiremnets of the UK Light Aircraft Association.
this is one of the big reasons I'm currently enjoying playing with cars rather than aircraft.

And Mark - what about slide throttles?

 

Not necessarily true. Yes, this is the case in the UK, where the LAA (light aircraft assiciation) has taken up a role from the CAA and are so serious about it that they rule out everything that departs from tried-and-true.

Here in Holland, I am allowed to do a LOT more on aircraft. Admittedly not quite as much as in the US, but registering an experimental aircraft is a lot easier here than doing the same for an experimental car.... Leading edge modifications as mentioned would not be illegal here....

Hans
(veteran of two subaru-powered aircraft)

 

Modified cars are also theoretically difficult here here in UK, but in practice if you use a chassis that has already been registered (or even a chassis number) you just register it with that number, get it MOT tested and that's that.

 

I'm sort of teasing you, but there's a saving of 12 x $35 to be made, offset only by a bit of your time and a bit of aluminium stock, and then the potential of EVEN MORE HP....

 

I would take you up on that, but I am not looking for superior airflow, I am simply testing to prove my theory that a person can port match the heads and manifolds by eyeball without a flowbench, and make more power. And while according to my flow bench it didnt work, I dont trust the data.

I have read discussions theorising low speed turbulence and vortices may occur in a port at low test pressures like we are using, such as 10 to 27 inches of water column. That this turbulence may increase as the port is opened, fooling us into opening it ever larger to get our flow back. Some have suggested that this turbulence completely disappears when the pressure is increased, and test pressures exceeding 40 inches are now being used, in fact some are even testing at 200 inches or more. Specifically they are attempting to bring port velocity to near the speed of sound.

In my own calculations, when I consider max flow rates into the engine at max rpm, depending on the time air is actually flowing into the cylinder, the air speed could be peaking in the 300 to 500 mph range. Yet we all know most of the time the air isnt moving at all because the valve is closed, and part of the time the valve is open the piston is actually pushing air outward (reversion). The duration of time air can actually flow inward is very short. I am considering the idea that at low engine speed the port velocity may peak at nearly as high of speeds that it does at max rpm, but in a shorter window of time. IOW, the dynamics change as the speed changes.

The fact that so many people over several decades have seen increases in power by port matching intake manifolds of many different engines by eyeball, without a flowbench, even some 308's, proves that it works in at least some cases. I have an eaton M90 blower available I want to try, I need to find a big motor to drive it where I can control speed and flow. Without anymore port work, I want to test the ports at high pressure, as high as I can get it. The M90 looks to be able to flow about 550 CFM at 12,000, so I should be able to get flow up there a ways. I still have unmodified ports, as well as the ones I port matched and I just want to prove one way or another whether this works or not. I have absolutely no interest or intention of doing anything more to the port than simply aligning and blending the manifold port into the head port. I have 30 year old Ferrari stuff, and no need to open it up until I hit water.

If in the end the flow bench can not prove anything conclusive, the only possibility would then be to test with a dynomometer. But thats not an undertaking I have the means to pursue. But I would still probably port match them either way, regardless, because I cant at this point see that it actually hurt anything, and a little more port volume might benifit the motor at low speed by possibly adding a bit more low speed torque. In reality it probably does very little, it just looks better. I guess what im saying is I would rather lose 1 or 2 HP and be able to look down those ports and see them line up, than see them all out of whack like they come from the factory. Ya know, ruin the handling by laying 9 pounds of lead on to smooth out that fender line so it looks better. That kind of thing.

 

Mark, could you post some more specific information on the valve seat cutter?

 

Thanks Mark!

 

I know the guys at Quicksilver Race Engines that used to do my formula car engines had some sort of honeycomb device for thier flowbench that allowed them to measure the swirl of the air going into the combustion chamber. I remember them telling me that you could have two heads that flowed the same but the one that made this round section of honeycomb spin the most in the combustion chamber more would make more power through more uniform combustion.

 

When I say I failed, in reality I just havnt gained any flow... Im still flowing almost exactly what it was before I took out the offset.

So what your saying then, is there would be no net increase in performance without a net increase in flow, regardless of port volume? It was my understanding that if you could maintain flow while increasing volume it would fatten up the bottom end. Is that unrealistic in your estimation? And are you equally convinced that higher test pressure is completely unnecessary?