B20 IM Power Gains over LS IM?

Do the short-rise b20 intake manifolds give more torque/power than the LS manifold? I’ve heard people say it gives a lot more. Let’s get the story straight =) Also most importantly, will it fit?

thanks guys

“the people” you mentioned are probably me. Everyone else says “no you gotta swtich the b20 manifold off for your ls one”, “you hafta swap in your ls manifold because your hood won’t close” :rocket: like engine swaping is about absolutes.

Like i say. I’m convinced that my b20 mani gives me a little more low end than my '90 ls mani. Top end i’m not sure. One quick look at the two showed that the b20 runner ports were a fair bit larger than the ls ports, ideally matching the b20 head ports. The thing is tho, the b20 plenum was actually narrower than my ls one (low end grunt design i guess).

My b20 mani also has a 60mm matchported (of course) tb (measured at the plate) compared to the ls’s 58mm. However, my ls tb was jg ported to 62mm, but big deal compared to all the other bottle necks. These two tb’s are not interchangable because of the different fast idle valve locations.

Vaccum tube routing was easy and all else i had to do was extend the map sensor connector from the firewall location to the new spot on the tb.

I also used my ls fuel rail because i couldn’t fit the fat ls fuel injector wires into the b20 plastic runner holder. I think thats all


'96 jdm b20b on the left and a '90 b18a on the right


copy that above link into your browser for a bigger pic


those two b20 gasket pieces are the same size, what a bottle neck!!

if u port match the LS manifold will it bring back the low end grunt to the b20b?

no 'cause the ports are wider right through, although not quite as pronounced as at the opening


im going to be sloppy with my words here please dont get the wrong idea. ur kind of saying that the b20b low rise is closer to a extrude-honed LS manifold???:shrug:

i don’t think so, the plenum on the b20 isn’t as fat as the b18a’s, which is supposed to be worse for high end power, but notice how the b20 mani sits much lower too…? I don’t know what all this equates to technically, but i won’t be going back to that b18a mani. I wish i had a b18b mani pic to compare with…