4age 20v head vs 16v head... Big cams and serious flow

[ke_70]

how many 20v's has gone over 250hp?

i vaguely remember when i was planning my 4age build reading hasselgren (i think?) built a fa spec 20v and it fell quite short of what they managed with the 16v

[Jimmee1990]

I would say that would be down to experience more than anything, they built 16v's for the last 15 years and rarely ever go that far with 20v's so they would be starting from scratch developement wise. There's a guy on club4ag that's nearing 280hp with a stroker 20v at the moment if you're curious.

[MAGIC MAN]

hey i thought this would open a discussion about 16v vs 20v. Although i have heard of high power 20v combos, the initial cost and up keep of these engines kinda put me off. Valve springs require frequent replacement, depending on black or silver top the head needs extensive mods for big cams, then there is a limited off the shelf parts list for pistons, cams etc..... And i already bought atlantic parts so makes sense to use 16v

The pic of the port i showed is not awesome, and the ports look far different from that now. So far i have spend approx 40+ hours on machining the head in ways to get it working better. The main draw back is the inlet port angle, the port as you know goes in horizontal then turns 75 deg to the back of the valve, i have decreased this angle down to 55 deg by raising the port roof and floor. This does slow down the high speed air but the increased flow outways the loss of bottom end torque, as the piston speed isn't there anyways. As the engine is a big air pump, more air in equals more fuel so more power in theory. The exhaust doesn't need as much work as its under pressure but it will still get a good tickle.

Now i could go all high tech and start changing various other parts, rod lengths etc.... But i have come to the conclusion not worth the cost, and if something does go wrong it is easier and quicker to use off the shelf parts to begin with. So less down time, and i can then afford to do two engines and have one on standby

There are a few other tricks i have got up my sleave, i wont keep them a secret but i am curious to see how many people pick up on them before i say anything. I will start posting some more pics soon, as im starting to mock up the block and accessories and an alloy flywheel so should be interesting.

[SamsTA22]

20v intake ports are smaller than the smallport intake ports... (although they are a better design)


Just curious, how big did you make that intake port?? its huge

Also, exhaust port flow is actually pretty important at high rpm, due to the amount of overlap the cams need at 9000+ rpm

[Matt]

Keen to see intake manifold design too

[MoNsTaR]

im interested to know what kind of flow figures you are getting, as at my work we've had issues with bigports due to the port being so large it easily looses velocity, one thing we do to combat this by using putty on the floor and raising the roof. any chance we could see more pics? those ports are HUGE haha

[rthy]

must be some serious cams to have to have ports that HUMONGUS

[Vaughn]

I shall wait for an update

[Delazy]

Just for the sake of the topic...

The stroker 260hp 20v 5.5ag motor from the US everyone is mentioning was built by one of the bigger (not hasslegren) FA series engine builders (quicksilver)...

it made very similar numbers on the flow bench to that of the FA 16v heads...motor still has abit left in it tune wise and isn't as yet running the hytech headers

It's also been mentioned on a couple forums by a number of wise heads that rumours have it a number of FA engine builders are trying to push for 20v heads to be allowed under series regs... Partly due to further developing the motor but also due to supposedly lack of appropriate 16v heads...

Ledwith racing in Ireland has also has some pretty serious CNC machines heads available at 2000euro a pop...a couple of these also having seen 250-260hp with appropriate supporting

[Sam-Q]

A very interesting thread.

Gunner in this case Bill is correct, however he is talking about the theory of 4 vs 5v not comparing the different 4age models. The 5v head is inferior to the 4 in non boosted form for these size of engines because of multiple things like middle intake valve shrouding, small bucket + spring diameters, poor quench zones/large chamber surface area and split chambers on the earlier engines.

However when Toyota went from the 16 to 20v design they made the intake port shape massively better, added a basic intake VVT, raised the compression and of course that awesome intake. So most of the time the head design that theoretically worse ends in one aspect ends up being superior in use. Take a 16V with the same design upgrades say like a 3sge BEAMS with a quad throttle conversion and you have something that makes real good useable power.


Now to this project here, In my limited experience I have yet to see someone try such work with a smallport. I am curious though Beau, why did you remove material off the bottom of the port? didn't want to weld the head for a gasket area if you took it all off the top?