Suck me beautiful (new pics monday 5th oct)

[Quan-Time]

crazy as it sounds, theres possibly truth to that devlin.

As for the airbox, i can flow a stock air box with paper filter, and i have a K&N, and ill flow that. It will be upwards of the 400cfm range, and my bench may max out. But i can certainly try and give it a shot at some stage and see whats what..

One thing would be to flow a carby, say its 200cfm, the box SHOULD flow 400cfm. If it flows anything less than that, theres an obvious restriction. Yer, def a good suggestion.

@ HansJ
Flowbench are used at increments of lift. I know that the stock cam is 8.0mm, and a kent grind is 8.4mm.
By doing 0.25mm lift increments, i can plot a graph to show where the weaknesses / strengths of the head lay. Low lift numbers, anything under 2mm, are fairly much dependant on valve shape and seat angles. By changing these, you get different values. Mid lift, from 2mm - 5mm, much of it has to do with the port floor and short side radius. High lift, upwards of 10mm, your looking at inlet and overall shape of the port. Everything has to work "together". Remember that the valve spends more time in the mid range rather than high lift. So theres no point having a head that can flow fantastically at 8.00 - 8.50mm lift, when its only there for around 10deg of the cam. Where as it spends close to 120deg of the cam in the mid lift values.
Remember that a valve both opens AND closes. Thats why it so much. You often have to find your "compromise" on certain areas. You might be able to get 250cfm @ 8mm - 8.5mm zone, but only 195cfm in 3.5 to 5.0mm lift. But by "choking" the port a touch, you get 235cfm in 8 - 8.5mm range, but as a by-result, you now have 215cfm in the 3.5 - 5.0mm lift range. When you calculate how much time it spends in these areas, its worth MORE air to port this method than the latter. Saying that, it really depends on your application.
To some extent, a poor working port can be complimented by a good cam grind. Open the valve slightly faster, hold it open a touch longer, but slap it shut. You still have the same "time it is open" as it were, but it spends different times. Slapping the valve closed can cause all sorts of headaches.. BUT for race engines that are always getting clearances measured, serviced, etc.. you will find its ok.. But you do tend to stretch valves, break springs, chip valve seats, etc..
But a lazy cam grind that is too "linear" can make a good head work like poopy. Its just "up and down" like a flowing roller coaster. Sure its great on wear and tear, and probably give you good economy too, but would REALLY sap away some power.

Find the limitations of the cylinder head, get a custom cam to suit it. Factory grinds are also a bit "passive" as they want economy and durability. Its why "kent" grind provides more power. But i suspect it would wear things out ever so slightly faster. But not by much. Possibly change valve life from ~120,000km to around 95,000 - 100,000km mark. So its not really huge.

http://www.tonyfoale.com/AermacchiEngine/

Have a look thru that and see whats possible with porting. You will find a chart at the top, and the process involved to get much better flow.
Tony only put those pics online today, im on a seperate email list with him.

[Quan-Time]

OK, here we go again.. some more updates on the throttle bodies.

You can see above the red wave on the top, thats where the injector penetrates into the throttle. Notice that its not "uniform" in shape. This makes bias air movements. Thats bad. Also notice at the bottom ive still got more to go, a step still remains.


The ridges that help shape the injector tunnel were sharp edge, and raw machined. Ive blended them in to match the holder.


You can see since ive blended the back side in, the uniformity has come into line nicely. It should all keep the same radius to help smooth out air travel.


You should get a fairly good idea of how it all goes now. You can see how its changed shape to match.


All in all, im NOT finished with it yet, not by a long shot, but im getting 215cfm @ 16", 280fps max, 230 average. Not sure how much more CFM i can get, maybe 218 if im lucky, but id like to see peak FPS hit the 300 mark, and get average to 250ish, or possibly 260. Wait and see really.