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Discussion Starter #1
Well thus far I have officially done two b20 head and IM's of course since I can't compete with Toofast's prices on TB's I just let these guys go thier own route, anyways I had recenlty started on a b21 head and IM and have come across these nice little revelations. For example after disassembling the b21 manifold I can tell you that from the factory it flows far better than the b20 especially if you're looking for a motor that will give you good midrange and top end, it just has a smoother casting and plus the plenum has a far better flowing design than the b20, the b20 has a more direct and tossed flow, however if you're looking for overall which one is the best to mod I'd have to put my money on the b20 mani, just becuase you can get rid of the secondary plate and make it a pure mid to top-end manifold, which is what I have made for my car, now I haven't tried this on a customers car becuase I want to make sure I get good gains out of it. and as for the valve dimensions on the b20-b21 they are both the same, however if you're a b21 owner, you're in serious luck becuase the valve reliefs are cut deeper which mean you can actually put a pretty radical set of cams and probably still clear your pistons, however if I were you I would seriously get a spare b20 head and just mill the shit out of it till you got an oval shaped combustion chamber like on the gsr, sure this would make the head a one time use piece only but think about it you get this from the junkyard for what 30-50 bucks a head gasket, shoot after about a 100 bucks you could bump your compression up considerably, I would have to cc the chambers but it's a good jump, also the combustion chamber diameters for the b21 are 82.7mm and the b20 is 81.8, now if you're a b20 owner and want a good upgrade with factory internals then get b21 pistons with 83mm bore, and toss them in. There is a lot of other information I am leaving out. But as usual I have a hidden agenda, I am going to be finishing the P&P on the head, and it'll be reassembled, the im is already done, I have the measurements on how much larger I went on the ports and the throttle-body inlent and all, but when I do sell this I am aiming to sell this to someone with a b21 with some considerable mods to take advantage of it. I am going to be perfectly honest with you on this I have put so much time and concentrated effort on this package that I cannot emphasize to you how proud I am with my work on this, I trully will hate to sell this, becuase this is some of the best work I have done, and the most extensive I have gone, so if anyone is interested toss me a pm and I'll keep you in the loop.
 

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Do keep me in the loop as I am doing something the same eccept doing it for myself. I have a good b20 and a rod thrown b21 that I'm trying to get the best of both worlds out of, problem is all of the negativity surrounding it. With so many parts interchangable it's nice to see someone else who doesn't simply rely on the phrase "If it was going to do anything better, Honda would have done it". Keep up the good work and please keep me informed!

William, Holland
 

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Yeah im a b21 owner, and its running fine, just the rattling and burning oil problems like always, been askin around and 1/2 the lude owners round here wont spill neting, due 2 the fact they think i might duplicate thier car in some way.........only so much u can do with it
 

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Kickass truck missed
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haha..

you bitch when someone post a question... you tell them to search.

then if someone does search and pulls up an old topic by asking a question in it, because it has the info they are looking for. you then bitch at how old it is.

not you personaly, of course.

got to love this group. :lol:
 

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LOL VTEC
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it would be ok if he asked a new question but he said keep me posted lol
reyke's manifolds were sweet i bought one from him a while ago off of ebay lol
 

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:lol:
Well I'm talking to the guy who sent ReyKe a PM, ReyKe barely ever posts anymore, and when he gets the PM hes going to be like "WTF is he talking about?".


Props to 2.1 Si for searching, but I dunno what he means by nobody will tell him anything....:?:
 

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LOL VTEC
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Unaturally Aspired said:
:lol:
Well I'm talking to the guy who sent ReyKe a PM, ReyKe barely ever posts anymore, and when he gets the PM hes going to be like "WTF is he talking about?".


Props to 2.1 Si for searching, but I dunno what he means by nobody will tell him anything....:?:
actually it DID happen lol.. i think 3 or 4 were made though.
If you'd search you'd have noticed :p
 

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New title is new
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Don't worry about it, everybody forgets to check the last post date from time to time :p
 

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Discussion Starter #13
Actually there's a member here who has a full intake and b20 head going on a b21 stock bottom end block, I still come on here to post and peruse, but thus far I have been battling my own car problems and plus my Mustang uses up a lot of my spare cash, sorry nitrous is damn addicting. But soon as I find my old car post I'll update everyone on my current car status
 

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i know this may be quite a little off topic, but im trying to get this straight, im thinking bout buying a 91si with a b21a1, but it slung rod through the block, or so i have been told. i was wandering what for now would be the quickest way to get it back to a daily driver. and also easiest on my pocket. you'll have to forgive me i ask questions that have been addresed allready just to make sure. its in my nature.
 

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buy a junkyard b20a5 block that doesnt have any holes in it, and preferably with a good crank. rebuild it with new rings and bearings, and throw her in your car. or you can have it bored out to fit b21 pistons.

i wouldnt suggest buying a junkyard b21 motor though. theres no real way to tell what kind of running condition its in without taking a lot of measurements
 

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it could be yeah, but you never know when that b21 will start sicking down more oil than gas. so its a gamble with no deffinite odds. it could start burning a quart of oil a day within a week of buying it. or it could go another 80,000 miles without burning a drop. or anywhere in between. no way to know til it happens.
personally, i wouldnt even bother gambling with a b21. id just get a decent b20 and rebuild it, or get a known well-running b20 and just drop it right in.
 

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so you can just bolt all the b21 stuff to the b20 block and drop it right in? is there anything else involved?
 

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so you can just bolt all the b21 stuff to the b20 block and drop it right in? is there anything else involved?
You will have to use the B21 flywheel in order to use the B21 clutch. Othere than that, you are just transferring all accerssories, Intake Manifold, exhaust manifold, Distributor etc all over to the B20.
 
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