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

[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.

[Delazy]

I believe the new Ferrera valves Anthony (250hp 5.5ag) developed exclusively are longer and drastically improve flow rates while being the same size due to redesigned shape .. Shall point him this way to contribute also ..

A topic I am quite interested in and will intend to add more in relation to prime86s last post, but being at work and stuck on iPhone doesn't help atm

[Prime86]

For the guys who don't know Hasselgrens 20V engine made 240hp on a standard stroke bottom end and the spark plug tubes weren't modified so that's a pretty impressive figure considering they would have been limited on the rpm to around or just over 9000. Yes it's short on power compaired to the later style 16V with Gandry fuel system and barrel throttles that makes 300hp.

Delazy is correct as far as the valves play a huge part in making the extra power in the topend Atlantic engines. Valve design and how far they are recessed in the head, seat design all play a part in extracting the extra hp. I believe Atlantic engines with a rebuilt head or what they call a used up head can loose as much 30hp from the valves and seats alone. Hasselgren does a 7 way valve grind on the top spec engines, which goes to show just how far they go to extract that power.

[Delazy]

to further this thread again...




hasselgren ported atlantic 16v head...




hasselgren ported 20v head

[Prime86]

Thanks for posting up the pics. The 16V head above is a head that Billy Andrea (Edmonds) had for sale a while ago. Billy is a personal friend of Paul Hasselgren and I believe he has a guy from his shop work after hours to build these heads. This head is ported to suit the TRD Atlantic throttle bodies and is rated for approx 245hp@10,000rpm.

[Delazy]

nice work spotting the head mate...the 20v head is billys personal head...which made 210hp

[Delazy]

this is the Ledwith racing CNC head from ireland...



this is anthonys 5.5ag 20v head as prepared by quicksilver

[Prime86]

Thanks mate, I have looked into these heads a lot...Lol.

What I found interesting is how nice and clean the entrance of the intake port is and yet the blending down the back is probably what most would call average. All Hasselgren heads are like this and I have seen discussions on how disappointed some people who have purchased these heads have been. Hasselgren obviously know the main points of how to get the head to flow and concentrate on them the rest is just a quick tidy up.

I know a guy here in OZ who purchased a 20V head from Tony with the HKS 20V stroker that Quicksilver race engines had done exactly the same as his head. This head came over bare and he has since got it built buy a head shop here. The first thing the guys said to him is they weren't happy with the quality of the port job and they would like to blend and clean it up before building the head even though it performed very well on the flow bench at Quicksilver.

[Prime86]

Those guys in Ireland know how to do it well. I remember seeing an AE86 rally car over there that would of been the most modified rally car I have ever seen it was a work of art with IRS, dogbox and the works done it was such an impressive car. The engine was a 20V that I'm sure was built by these guys and it was claimed at the time to be 280hp and had the dyno sheet with it.