B20 Swap Help

[MtnCRX]

Im planning to do a all motor b20 vtec swap in my 90 Crx Si. Im still pretty new to the whole car tuning world, so this will be in 6 months to a year. Most of my knowledge has been from LOTS of reading in the past 3 months or so, but finding b20 swap info isnt easy. Ive decided on the b20b block with a b16a vtec head/ecu. Does the b16a ECU need to be modded? If it doesn't should I do it anyway? If so, what company would be good to do this?(DINAN, Spoon, Mugen etc?) ANother question I have is about the intake manifold. Would the b20b intake manifold be the best or should I go with something else? WHat is the difference between the JDM intake manifold and the USDM intake manifold? What kind of injectors should I put in with it? What about aftermarket pistons/rods/cams? One last question is about the tranny. WHat is the optimal tranny to match it with? I know I need a B series, and have been hearing a lot about the GSR tranny, but need better info. Sorry about the long post but Im really looking to build this thing up, and have been planning for about 3 months now so Id appreciate any advice or websites you can give me. Thanks a lot.

P.S. If youre gonna wail on me, just make it short.

[MtnCRX]

Me again.. I found out the intake manifold is too tall to clear the hood, so which one would be best to match the b20? Also, Ive read that the CRX SI ecu can be programmed to work with the B-series swap. Is this true?

[maxspeedhonda]

I can't help you with the ecu thing, because I am not really sure about it. A general rule of thumb is to match the ecu with the head but I am not sure in your case. As for the intake manifold, use the b16 one or maybe even a oem type r. Remember, the intake manifold mates with the head and has nothing to do with what block you use. Everyone will tell you that you should upgrade at least the injectors with a b20 setup, 310cc is a good size for that NA buildup, bigger for FI. As a matter of fact I have a set of RC 310cc that came with a turbo kit (used for about a month) that I could sell cheap. Aftermarket pistons/rods/cams?, Sure if you want to spend the cash. High compression=NA and low compression=FI. Its really a matter of how much you want to spend. As for the tranny, yes a gsr tranny would work well. If your crx has a cable tranny now (i think it does?) then you would have to do a hydro conv with can be a pain in the ass but is worth it IMO or to simplify things just get a 1st gen b16a cable tranny.

[MtnCRX]

About the short geared trannies... If the B20 makes so much power at even 3000 rpms because of its flat torque line, wouldn't it be better to get a tranny with gears a little bit longer? If the power band starts so much lower than a b16, isn't it kind of pointless shifting into 4500 rpms when your making perfectly good power at 3500?

[maxspeedhonda]

Good point, LS trannys have longer gears. What some pro drags do with a high torque setup like that are use heavier flywheels. Just a thought.

[th_james2003]

use a ls intake manifold.

[MtnCRX]

From what I hear, the b16 intake manifolds have the best flow so I'd really like to use one of those. Would it just be better to get an aftermarket skunk2 intake mani that goes on a 94 del sol DOHC VTEC/99-00Civic SI (same one I believe..), or would it really make a difference in performance over the b16 IM or the LS IM?

[maxspeedhonda]

Originally Posted by MtnCRX

From what I hear, the b16 intake manifolds have the best flow so I'd really like to use one of those. Would it just be better to get an aftermarket skunk2 intake mani that goes on a 94 del sol DOHC VTEC/99-00Civic SI (same one I believe..), or would it really make a difference in performance over the b16 IM or the LS IM?

B16 flows much better than a ls or gsr. Go with a oem type r manifold, they are all over ebay for cheap, if not then a 2nd gen b16a. The price on those skunk2 manifold is pretty high, and you are mostly paying for looks. For the price of those you could port out a b16a manifold much better.

[Jeff C]

Originally Posted by th_james2003

use a ls intake manifold.

That wont bolt up to a vtec head.