20B Series
Hi;
Ive got a question about the different block series of the 20B, whats the differents between A, B C and D? Can anyone explain it to me please. Thank you |
the castings were stronger starting from A-E..... E being the rarest and strongest housings of the irons.
i've read somewhere on the 20B section that the early build A and B codes could only handle minimal hp gains over stock before certain places cracked |
Originally Posted by cptpain
(Post 8493918)
the castings were stronger starting from A-E..... E being the rarest and strongest housings of the irons.
I've actually heard astute people like Steve Kan and Bob Putman, say that the "E" series are just myths. ;) |
bob are you talking yourself up again? lol
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Originally Posted by hoofhearted
(Post 8494516)
"E" Series...Has anyone actually seen one. Not pictures, but actually seen one? I've heard stories that Addkins had two, but has any one really "seen" one?
I've actually heard astute people like Steve Kan and Bob Putman, say that the "E" series are just myths. ;) REgards |
So the differents between C & D is just harder iron castings for more boost, less friction.:)
Ok if thats all :) |
Originally Posted by damic
(Post 8498715)
So the differents between C & D is just harder iron castings for more boost, less friction.:)
Ok if thats all :) D has dowel pins; do A and B have them? |
Originally Posted by hoofhearted
(Post 8500472)
Is there a difference between C and D series?
D has dowel pins; do A and B have them? All rotary's have dowel pins. |
Upgraded E-Shaft
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From the "What 20B# Do You Have?" thread on this forum (https://www.rx7club.com/showthread.p...light=what+20b) :
This is a basic way to understand your 20B engine 000 - 999 = 1st batch A000-A999= 2nd batch B000-B999= 3rd batch C000-C999= 4th batch D000-D999= 5th batch E000-E999= 6th batch (only heard of these, never seen one) I have never heard of an F-series. Since Mazda made just under 4000 20B version Cosmo's I can also picture that the E-series was for warranty replacements if they exist at all. If the engine has black on the rotor housings & the batch number stamp isn't on there, then its an internal factory rebuilt engine. (meaning its been out in a car & returned after failing within the warranty period) The last engines to go into a car would have stopped around "D500" for fitment into a Cosmo. For example......... The last Cosmo sold by Mazda = JCES-100633 However, Mazda quote selling just 369 examples of this series-II version so how it got to #633, I really don't understand. The latest Cosmo we have ever imported is JCES-100309. Its engine batch # D442 It was a AUG-95 car & production ceased in Sep-95. If you have any quiries then conact us via http://www.dmrh.com.au The A series engines were prone to failure because of weak intermediate irons. This was corrected early on in the B series engines. |
Originally Posted by DMRH
(Post 8495091)
Mazda never did a run of "E-series" engines but they did rebuild plenty of engines after the "D-series" for warranty replacements. You can tell the warranty engines from the black paint on the top edge of the rotor housing were it says Mazda 20B
REgards mine was not a rebuild |
Mine is #756. All housings are stamped. No black paint anywhere. It shows signs of possibly having been rebuilt. I'll know which shaft it has after I open it up.
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Originally Posted by Jeff20B
(Post 8519296)
Mine is #756. All housings are stamped. No black paint anywhere. It shows signs of possibly having been rebuilt. I'll know which shaft it has after I open it up.
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No letter. It's an oldie. That's why I've got to open it up to check out the shaft to see whether it's been upgraded because the engine shows signs of possibly having been rebuilt. If it's the old style shaft I won't even bother boosting it. It'll go into a 1st gen NA so it ought to last a long time and make plenty of power in the chassis.
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whats the difference in the shafts?
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The later style has a front taper and is stronger where the front rotor journal collar sits.
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so if i was looking for a reliable 20B, which one would i look for?
or does it just matter how much boost? |
you want a B,C,or D
The 0 and A series had weaker castings around the factory dowel pins, meaning they break under high boost and/or detonation. I have broken mine twice at 18-20 PSI (600+WHP) due to wastegate issues. Fortunately, welding technology has progessed to where even cast intermediate irons are repairable. I haven't had any problems with the e-shaft. Pat |
You mean about B8XX and up as the early B code motors are small Dowel pin land...
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awesome thanks!
one more thing, could someone tell me which thread would be right to ask about buying a 3rd gen RX7 and putting a 20B in it? i looked around and im confused of which thread to ask that in... thanks! |
Originally Posted by 20BTTwannaBE
(Post 8595391)
awesome thanks!
one more thing, could someone tell me which thread would be right to ask about buying a 3rd gen RX7 and putting a 20B in it? i looked around and im confused of which thread to ask that in... thanks! David Hayes |
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