I was wondering if anyone knew what kind of horsepower numbers the B21 motor found in the '91 Prelude si puts out? I'm guessing around 170, because I raced my friend who has a Type-S, and kept up with him. Anything will help.

 

lol, i'm pretty sure it's 135 brotha, and a type s what? prelude? as in japan? or as in 4gen SOHC nonvtec? i know from experience those things are as slow as christmas

 

2 small corrections.

the b21 is rated at 140 to the fly wheel, a bit more than the 135 that the b20 is rated at.

and 2, christmas is not slow.

 

then why do people tell me to get a B20 for my 90si instead of the B21a1 that came in it. I personally thought the B21a1 is better with its very strange 2.1l engine.

 

lol, maybe it's not slow to you, but it's slow to me

 

most people go with the 2.0 cause there are more parts available. the motors are basically the same with a few strange exceptions. I had a 2.1 in my lude and it needed rebuilt so i couldn't afford the down time so I built a 2.0 cause I had one. Also Tom @ludespeed.com said it would be easier to put a b16 head on the 2.0. I have abandoned that idea now and plan on running my 2.1 boosted to 15-20lbs. But I fully intend on going to the 2.1 after I build it. The 5hp's isn't much but the torque is what helps. When My 2.1 was N/A I used to beat up on 2.0 ludes it was weird.

Any ? about your lude e mail me cause when it comes to the 3g I have been there and done that.

Wayne
chinasta@aol.com

 

The b21 doesn't lack any aftermarket support and its no harder to put a b16 head on a b20 than a b21. The only difference between the engines are the internals. Honda bored out the block to get the extra displacement. Since the walls got thinner, they opted to fiber impregnate them to make them stronger. Since the Prelude was the first to get the frm cyl walls, I guess they misss calculated the difference in wear characteristics between the piston rings and cylinder walls. Long story short, the b21 eats piston rings giving it the common problem of excessive oil consumption.