4 Cylinder white engine, absolute max airflow?

[Jussi Alanko]

So, i had bought a 81mm bore block, i had a 2.0t crank.
Everybody knows what i need next 2000-2004 b4204s cylinder head with solid lifters.

I will try to make myself a flowhbench, it iis like longer term project so i don't think that i can measure my own porting.
But i section my porting work at different sections and get it to proper flowbench, my friend builds engines for work...

I do not make ports themshelf much larger, maybe 10% max, but more important is flow, laminar/turbulent, speed changes drastically which means pressure drops in differents part of the port-seat-valve combination. So, i can put a 33mm intake valve to it quite cheaply, at Kl-racing stainless valves (33mm, stainless steel) cost about 150€, But seatwork is going to cost, i maybe can get rid off old seats (with modified old intake valves that can be welded to seat, then put in a owen the cylinder head, wait at least one hour, then just whack them out. But installing a new seats is different thing and of course you had to be able to cut proper seat angles to it!

Lest think for a moment that i can get seats and valvework to be done at 500€, which is a pure guess, i have made these things about 20 years ago to b23 motors etc.

How much the intake channel flows as a whole, i do not measure it with an intake manifold on( because overpressures n turbe engines and various other reasons that will affect negative to cfm number but in a real world could get an engine either reactive or sluggish... too long to explain in this kind of format.

 

[Jussi Alanko]

I write a little bit more, i need a good reaction engine which makes power at 1.2-1,3bar max boost (is about 18psi) and little bit more Rpm.

I need to engine rev happily to quite a bit, somewhere like 8200rpm rev limiter, and with smallest possible cam, so that i can get even some dynamic compression ratio to it without crazy static. Of course this will affect at relationships between valve events. I had to drive 98e + water-meth combination, just because in my hometown there is no e85 at pump, any pump.

I think that this kind of profile is what i need:
INT Clearance cold 0.20mm
Clearance hot
Duration 262
Duration 1 mm/ 230 valve events: 5-45, Max cam lift 10.16mm
Lobe centerline: In lobe centerline 110
Ex lobe centerline: 110

EXT Clearance cold 0.25mm
Clearance hot
Duration 262
Duration 1 mm/230, valve events 45-5
Max cam lift 10.16mm

This is like on the shelf profile, something about 150-170€/Camshaft.

But, i know that i can get 200cfm with og valve sizes etc.
But what i don't know is: how much it will flow at 33mm valves with relly good porting, made with a thought rather than with a max sized channel...

 

[Jussi Alanko]

Because this topic has no answers i had to do the hard work, MATH!!!

I have made my own calculations, based on og intake port and valve size. 220cfm is possible.

And if yout put a 33mm intake valves and enlarge cross sectional area about all parts of intake port but especially at the sides and roof, of course.
And you need to put new valve seats. If you can grow cross sectional area enough, and do a proper valve job etc, then i think, i calculated that in 11mm lift 20% enlarged intake port can flow 275cfm maybe more and what's even more important than flow at max lift is flow at low and medium lifts.

One good thing, is exhaust port, it flows even at og valve sizes something about 75-80% of intake flow...

In turbomotor that's not so important, but what is important in turbos is stopping exhaust reversing, easiest way to do this is just port your exhaust manifolds flange about 2mm larger than exhaust port is in cylinder head. And this had to be taken account also when you are changing camshafts, here in Finland is a lot's of camshaft grinders, which can grind from your og camshafts very much just like you want. There is some limitations especially concerning exact valve events and of course if you need just 2mm more lift this is not going to work without prolonged durations also, other way around it work, you can have more duration without more lift. But when you had to raise your dynamic cr it can't be done any other way but to delay exhaust valve opening point, which also reduce overlap, which in turbo engines is good thing.
If you have proper fuel and good engine management system you can keep static cr somewhere at 9.5-9.8 and dynamic cr relatively close to that number, and static cr is nothing but a number, dynamic is what really deciding example octane rating etc.

There is some other things to do, but those need a fully constructed and very good designed exhaust headers...