i have a 90 prelude with a b21a1,ive heard that a b20 and b21 are the virtually the same except the b21 is bored out, now with that said ive heard of people putting a vtec head on a b20,does that mean that i can put a vtec head on the b21?

 

I've never done any modifications to a 3G, but isn't it easier to drop in an H22?

 

i think the answer is no, i don't think the prelude b series has too much in common with the civic/integra b-series

 

yes but i dont like how low the oil pan sits below the frame with the h22.ive seen some where the oil pan is like 4 inches off the ground at stock hight and mine is lowered so if i swap ill scrape evey little pebble

 

Someone on a different did it a long time ago. Not worth the time and headache. Get rid of the b21 and get a b20a5 and boost it.

 

ive talked to several people about the b20 vs b21 and many of them said the b21 has more power

 

The B21 does have more power.

 

The answer to your question is no. The B20/21 motors do not handle high rpms well. There was a couple people that tried this and for the amount of money dropped into making this a reality, it did not have good power, it was not reliable, and it took a very sizeable amount of money to machine the blocks to make them fit.

After that, the tuning was another cost that was high.

If you want real power, you need to either turbo charge or swap to the H22/23.

Since height is an issue for you, I recommend you go the route of turbo charging.

I personally just finnished my H23 swap and once I get the Traction bar, I will lower it down again, but not as low as before. But I own the Ksports as well so I am able to stiffen my ride to keep the pan or down pipe from hitting anything.

I love the power of the H22/23 in NA form for the 3rd gen, reliability and great power.