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

[MAGIC MAN]

ok so 4ag needs to flow to ensure good power, as small port is well as i believe to small the big port was to be the base for the project, so i will now introduce you to, the monster bigport. Initial rough porting shows the general idea to get large amount of air into small space with high port velocity well as high as possible. As it is a race only engine i don't care to much for bottom end power as i plan on it spending most of its above 5000, the test port is nearly completed minus some light blending (pic of this not here yet) Initial flow figures looking very promising. The 250hp mark is looking fairly achivable

[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?

[Prime86]

You are right about Hasselgren building a 20v head. It was built for a rally team that was bound to stick with a 20v engine or im sure Paul would have talked him out of it. A lot of work went into that head and I know that they made a spare that was never used. I have seen pic's of the head, they used the TRD Atlantic Throttle bodies on that engine but they run into problems with not making power. This was solved with the use of a special custom made adaptor between the throttles to head mounting face. The spare head was for sale a few years ago and a lot of questions were asked about the adaptor that came with the head as a matched set but it was all kept pretty secret and for only the buyer to know.

Tony the guy on Club4ag with the HKS 20v stroker that made just over 250hp@9000rpm on a engine dyno before it flew to pieces. Magic man is onto it, nobody makes high lift cams for a 20v head or not as high as a 16v up to or over 11mm as they hit the spark plug tubes. Because of this nobody makes pistons either and custom cams and pistons were made but they made a mistake with the valve recess in the pistons not been deep enough for the 10.5mm cams. Theres a guy here in Perth who builds a custom 1.9L 20V stroker with custom forged crank, rods, pistons and they are up at the 250hp range on race fuel. You can only rev the 20v engine to when the cams run out of legs so as a result the 20v is at a disadvantage as a 16v can be revved higher to make the power.

Hasselgren start with a small port head and port it to bigger than a Bigport as it allows more flexibility with port shape rather than size. When TRD quads are used they are at the size they need to be already, so in turn the head is ported to match the manifold not the manifold to suit the head and they remove the material from the side of the head as Magic man has done to suit the manifold length. Also I believe there is a different method when porting a head that is to be used with carbs as the port shape is different to suit.

[Sam-Q]

what I don't understand is why none of the serious tuners have fitted longer valves to the 20v engines. How about this: if 2mm longer valves where used then the buckets would sit 2mm further up. From here take 2mm off the base circle of the cams and then there is a new increase lift of the same amount without the height of the cam lobe being increased at all. The only real limit is the journal size which on a 20v is much smaller than the base circle size, so in short lots of material to use. Even the stock cams could be reground to have a harsh ramp rate with big lift.