View Full Version : B21A1 build
91Si4WS
10-04-2006, 11:19 PM
ok i have another B21A1 complete motor laying around and i want to do a N/A build with it, i want to keep the B21A1 cause its a 4WS lude so i want to keep it somewhat original, i know i want to micropolish and knife edge the crank with JE 12:1 comp pistons and Eagle rods, but my problem is the head, i can't seem to find Cams or anything for it. has anyone done a build on this motor? looking for some suggestions, i'm looking to get around 200whp cause im aiming for more handleing purposes out of the lude, but i still want some respectable power, and + it's my daily driver... i have the CRX for grudge running on the weekends at the track
InvaderTrax
10-05-2006, 12:33 AM
For cams, check out deltacam.com. They take your old cams and regrind them to the specs you decide on. Normally their "stage 1" spec is compatible with your stock valve springs. I know plenty of people with Delta cams and they're holding up great. Then find a shop that will do a P&P of your head and intake manifold (or do it yourself), then send your throttle body and intake to maxbore.com and they'll bore it out as much as possible (did mine and it's worth $160)
Prelude13
10-05-2006, 12:03 PM
Your problem is not the head.
It's the FRM you should be concerned about.
How are you going to use 12:1 JE pistons when the FRM will eat them alive?
First things first, you need to properly hone the FRM sleeves, meaning you need to find a place that has the Honda honing tool, the proper grit to hone the sleeves. Either that, or you completely resleeve the b21a1 block and get rid of the FRM.
The b21a1 is a tricky motor to work with, thus called, "Bastard B series."
I consider it the FATHER of the B series...F1 technology.
Did you guys know, the b20a was supposed to be turbocharged from the factory? YES.
:tup:
91Si4WS
10-05-2006, 02:12 PM
well i think its gonna be more of a trial and error thing, i have one compleate motor to work with that was still running fine when we took it out of the other prelude (compleate meaning still has head, tranny, intake manifold, exaust manifold, on it) plus a spare ecu, and ontop of that i have another B21A1 crank, Intake manifold and head. I have plenty of time to do the build too because the B21 that is in my car is still running great! I just turned 145000 miles on it. I dont see why if get the FRM sleeves honed right and do a good 3000 mile break in on the built motor and keep up with my 2000 mile oil changes why i couldn't get an easy 100,000 out of it.
Prelude13
10-05-2006, 03:05 PM
If you can find a place that has the proper grit stone that can hone the sleeves, pshhh, all you have to do is re-ring the pistons and you're good to go another 200,000k.
The problem is, not many shops will have that specific grit to hone.
Reading a lot of testimonials of other people who have done a tear down and rebuild on the b21a1 say that 2 out of 3 sleeves still have the cross-hatchings visable to the eye.
This FRM sh-t is that strong. Y0.
My question to you, do you burn oil?
I certainly do, about 1 qt to 500 miles; but of course I do 100% city driving.
Also, rest assured, your b21a1 pk3 intake manifold and mine is far superior to the dual runner b20a5/b20a IM's.
:)
edit:
Another way to avoid this FRM nonsense is finding a b20a5 block & over-boring it to fit b21a1 pk3 pistons.
This way you will have a bump in displacement/compression with iron sleeves and not worry about oil burning or piston rings being chewed ever.
:tup:
ogsmakdade
10-05-2006, 03:56 PM
check out pocketrocketsracing.com for any machine work youcould possibly need.
crane makes cams for your motor, you'll have to call them though because I can't find the info on their website.
THE ONE
10-05-2006, 10:01 PM
ok.... I'll like to say I back your decision 200% with this motor. it is different and I can only think of one other person that have built a prelude b series engine (fly from pp). So I'm very interested in this. I have one question for third gen gurus. Can't the LS integra cams made by crower called 402/403/404's work on that b21a head? Cause if that's the case then 91si4ws is in business.
an those fit? Thats the question... If they can I wouldn't suppose they would be a direct fit. I'm pretty sure you'd have to do some customizations for them to work.
Prelude13
10-05-2006, 10:45 PM
b18B intake cam is golden.
There is a group buy going on now at Pp.com, from Steve my personal friend.
B21a1 exhaust cam is also superior to any B series motor, non vtec that is.
So leave that exhaust cam and source a b18b intake cam.
:tup:
THE ONE
10-05-2006, 10:50 PM
haha! I knew I knew a little some'n some'n about third gens!
91Si4WS
10-06-2006, 12:02 AM
ok so yall are saying leave my stock exhaust cam then use a B18 Intake cam? I mean if that will work that will be great because it will help me out on costs a lot, but would it be better or as dependable than a new set of crane cams?
And yes prelude13, it does burn oil about a quart every 750 to 1000 miles, but i'm on the interstate for half of those miles. It has more of a problem with black carbon smoke due to the fact that the converter has blown through, but as of next week there wont be one on there at all. then im finally going to take one of my other stock exhaust manifolds to a buddy of mine so he will have something to go by for the header that he is going to build me!
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