Topic: 20r head swap

[abnormaltoy]

Alright y’all, I got some questions.
I was reading another post and it brought to mind some things.
I’ve got an 88 EFI engine, 94mm, forged pistons, about 11:1 comp, SDS fuel and ignition, a worked LCE head.
What’s the poop with the 20r head swap? I know it’s a hemi and is supposed to flow better than a 22re head. But I gather the increase is at the top of the power band.
With low gearing can that still be useful for rock crawling?
Where does the power band move?
Can you keep EFI?
Does the hardware swap over? (rocker assy, cam, etc.)
My inclination would be to go with a supercharger, but I’m always interested.
C’mon, give me the skinny!
 

[79coyotefrg]

on 94mm block a 20R head is going to have very little surface to seal  the head, if you do,  use a toyota headgasket  or the LCEngineering headgasket,  anything else will blow water into the cylinder

the real power gains are 3000-5500 rpm

[79coyotefrg]

you'll need somebody like Willymammoth to make the efi work on the 20R head

[79coyotefrg]

11:1  + supercharged =   hope your gonna run propane 

[79coyotefrg]

always use the 22R rockers,  cams are the same more or less

[abnormaltoy [OP]]

11:1  + supercharged =   hope your gonna run propane 

Well, it's a while down the road yet for that...but I can still plan can't I?
If you look at some of the current generation of Super'd cars most of them are running 10.5 or 11 compression ratio. From what I've been told a low boost (5-6psi) and high comp will result in way big torque.I might run propane, one of these days!

[abnormaltoy [OP]]

you'll need somebody like Willymammoth to make the efi work on the 20R head

I take it that the intake manifolds don't match up? Well, I've got nothing against modifying one or making a new one!
What about the exhaust side?

[79coyotefrg]

exhaust side is a direct bolt on 


my motor  had like 10:1  and when running the 87  and pulling a load,  it detonated to much and killed my piston    thats what bigmike said anyway,  and it had something very bad  happeneing in there

[abnormaltoy [OP]]

exhaust side is a direct bolt on 


my motor  had like 10:1  and when running the 87  and pulling a load,  it detonated to much and killed my piston    thats what bigmike said anyway,  and it had something very bad  happeneing in there

Yeah, I saw that piston...not good!

[kneedownnate]

My 81 stock block and 76 celica head detonates under light loads!  There's no reason to use the 22r intake manifold either, the 20r manifold breathes a little better if I remember right.  You can get an adapter from LC engineering to run your 22r carb on the 20r intake too, if that's the way you wanna go.  Power is definately better on top too, it'll pull atleast another 1000 rpm if not more over the 22r, depending on your setup.

[kneedownnate]

As far as running efi on the 20r head, dig up my old thread about exactly that and there's a great link near the bottom for doing so.  I've wanted to do that for quite a while, and think the combined benefits would be great.

[kyle_22r]

the head doesn't necessarily flow better, but the pattern is much better.  it's like comparing the head on the 258 AMC six with the 4.0HO six.  the 4.0 has a straight shot to the cylinder, while the 258 head goes around a 90* bend.

the 20R ports are a bit smaller than the 22R, but the 22R has a swirl ledge for less emissions(helps the mixture burn more evenly).  however, a 20R head will boost your midrange torque and let you rev much higher.  i missed the off-the-line grunt of my old 22R at first but learned to love the powerband.  the intake manifold is a better design, has 4 nice long runners rather than 2 big ones that split halfway to the ports like the 22R.

[kneedownnate]

Strangely the only real difference I felt going from the 22r to hybrid was the top end.  Never felt a noticable diff on bottom, but it did pull slightly better in mid I guess, and top is a whole nother ball game!