So, it's possible to use 2nd gen N/A housings in our FD'S? - RX7Club.com - Mazda RX7 Forum

Go Back  RX7Club.com - Mazda RX7 Forum > Generation Specific > 3rd Generation Specific (1993-2002) > 3rd Gen Archives
Reload this Page >

So, it's possible to use 2nd gen N/A housings in our FD'S?

So, it's possible to use 2nd gen N/A housings in our FD'S?

 

 
 
 
Old 09-20-04, 09:09 PM
  #1  
Banned. I got OWNED!!!
Thread Starter
 
Gargamel's Avatar
 
Join Date: Dec 2003
Location: The land of Lincoln
Posts: 1,783
Thanks: 0
Thanked 0 Times in 0 Posts
So, it's possible to use 2nd gen N/A housings in our FD'S?

From what I'm reading it seems that it's indeed possible to use 2nd gen N/A housings if you cut out the "L'S". I always thought that it would work but didn't know if anyone actually tried it. Looks like Kevin Landers does this quite often?

Anyone else use them?
Gargamel is offline  
Old 09-21-04, 12:24 AM
  #2  
Lives on the Forum

iTrader: (8)
 
RotaryResurrection's Avatar
 
Join Date: Oct 2003
Location: Morristown, TN (east of Knoxville)
Posts: 11,482
Thanks: 0
Thanked 1 Time in 1 Post
I do not do this for customer engines unless they know up front the differences and agree to the mod. The times when this is helpful is if, say, both your FD housings are trash and you cant find decent stock FD replacements and dont wanna drop well over a grand on 2 new ones.

The housing specs are as follows.

85 and prior: chrome flake badly, coolant o-ring groove is cut into the rotorhousing, not the iron. Small exhaust port. Not useable in any 86+ engine.

86-88 nonturbo: chrome flake and compression surface wears moderately, most of these aren't in very good condition if they have over 100k miles. They're usually fine to reuse in a street nonturbo engine, but not for something like a modded t2 or an FD. They have the noise diffusers in the exhaust, so you can either cut them out or swap sleeves entirely. The port itself is identical. Plug timing is different from 89+, and these do not have the casting above the T plug for the knock sensors. Required 4 oil injectors for lube.

87-88 turbo: same as above, except with smooth exhaust port identical to FD. Also they have an additional coolant passage where the LIM bolts up, on FC's this feeds water to the stock turbo through teh LIM which has a drilled passage. To use this housing on an FD you'd have to plug the coolant passage.

89-91 nonturbo: chrome flakes and wears very mildly, holds up quite a bit better than 88 and back due to a change in coating. Still required 4 oil injectors for lube. Plug timing is changed, and matches the FD housings. All 89+ housings have the holes for knock sensors above the T plug. The NA housings have the exhaust diffuser issue that must be addressed. The NA housings do not have the coolant passage at the LIM. So, if you mod the exhaust port to your desires, this housing is almost identical to an FD housing, and usually will exhibit a similar amount of wear.

89-91 turbo: same as above but has smoothport exhaust and the coolant passage issue at the LIM.

93-95 FD: went to a better internal coating for slightly less wear, also required less lubrication, so they went from 4 oil injectors on all previous models to 2 on the FD. Smoothport exhaust sleeve, same as s5 NA in all other regards.

yes, you can mix and match housings of all kinds, this is the beauty of 13B engines after 86. You can purpose build an engine for many different requirements because of this. You can do complete rotating assy swaps, change irons for different intake port configurations, or improvise out of necessity.

For example, I build a few GSLSE 1gen 13b engines now and then. As noted above, the coolant seal configuration is different, and the rotorhousings usualy come out shitty and useless. I usually build hybrid engines for these guys. I use 86-88 NA irons which have the coolant passage cut into them, and bigger secondary intake ports to begin with. I use 89-91 NA rotorhousings with the diffuser cut out...they have very little wear on them so they build a nice strong enigne, plus the exhaust port is much larger than the stock one on the old rotorhousing. I keep the stock rotating assembly unless otherwise requested. I use the original front cover and it bolts up like stock, but runs much stronger.

Last edited by RotaryResurrection; 09-21-04 at 12:27 AM.
RotaryResurrection is offline  
Old 09-21-04, 01:25 AM
  #3  
Rotor Head Extreme
iTrader: (8)
 
t-von's Avatar
 
Join Date: Apr 2002
Location: Midland Texas
Posts: 6,693
Thanks: 0
Thanked 5 Times in 4 Posts
Damn this great info. This needs to be archived.
t-von is offline  
Old 09-21-04, 01:27 AM
  #4  
Original Gangster/Rotary!
iTrader: (204)
 
GoodfellaFD3S's Avatar
 
Join Date: Mar 2001
Location: FL-->NJ/NYC again!
Posts: 29,966
Thanked 100 Times in 89 Posts
^ Now that, ladies and gentleman, is a good ******* post. Thanks, Kevin .
GoodfellaFD3S is offline  
Old 09-21-04, 01:45 AM
  #5  
Power Trippin'
iTrader: (4)
 
SpeedKing's Avatar
 
Join Date: Nov 2003
Location: Land of The Quick
Posts: 3,130
Thanks: 0
Thanked 1 Time in 1 Post
Yes, an absolutely first class post.

And who is this assclown, "spec99", to question your expertise?
SpeedKing is offline  
Old 09-21-04, 03:03 AM
  #6  
R1derful
5 Year Member
 
Sonny's Avatar
 
Join Date: Feb 2004
Location: N Cali
Posts: 703
Thanks: 0
Thanked 0 Times in 0 Posts
Good info, Kevin.

Sonny
Sonny is offline  
Old 09-21-04, 08:34 AM
  #7  
Banned. I got OWNED!!!
Thread Starter
 
Gargamel's Avatar
 
Join Date: Dec 2003
Location: The land of Lincoln
Posts: 1,783
Thanks: 0
Thanked 0 Times in 0 Posts
Thanks Kevin, great info.

Time to save some money.
Gargamel is offline  
Old 09-21-04, 09:52 AM
  #8  
Banned
10 Year Member
 
95R2-89TII Ground Zero's Avatar
 
Join Date: Jul 2001
Location: Rochester, MI
Posts: 2,519
Thanks: 0
Thanked 0 Times in 0 Posts
That is a great post....now I can impress with my knowledge.
95R2-89TII Ground Zero is offline  
Old 09-21-04, 09:56 AM
  #9  
Rotorally Challenged
10 Year Member
 
jeff48's Avatar
 
Join Date: Apr 2002
Location: Southern Illinois
Posts: 1,512
Thanks: 0
Thanked 0 Times in 0 Posts
Thank you Kevin. Somehow, even though I had no idea who you were, I sensed you knew your craft. Now you prove it IN SPADES.

Moderators.
Please archive or sticky this thread. It is some of the most valuable and clear material ever written.
jeff48 is offline  
Old 09-21-04, 10:18 AM
  #10  
DGRR 2017 4/26-4/30, 2017
iTrader: (13)
 
Herblenny's Avatar
 
Join Date: Nov 2001
Location: Alabama
Posts: 13,597
Thanks: 0
Thanked 1 Time in 1 Post
Kevin,

I've heard somewhere that you can not mix match the housings, ie FD front and T2 rear.... Unless you are going to match the front and rear housing (either FD's or T2).. Apprently due to slight tolarence difference between the housings.. And same goes with the rotors.
If I'm wrong please let me know.. I will correct the person who told me..
Herblenny is offline  
Old 09-21-04, 10:21 AM
  #11  
Banned. I got OWNED!!!
Thread Starter
 
Gargamel's Avatar
 
Join Date: Dec 2003
Location: The land of Lincoln
Posts: 1,783
Thanks: 0
Thanked 0 Times in 0 Posts
Kevin, can you post information about swappng T2 rotors, ie; matching letters.
Gargamel is offline  
Old 09-21-04, 11:13 AM
  #12  
Lives on the Forum

iTrader: (8)
 
RotaryResurrection's Avatar
 
Join Date: Oct 2003
Location: Morristown, TN (east of Knoxville)
Posts: 11,482
Thanks: 0
Thanked 1 Time in 1 Post
Heh, finally a well recieved post in the FD section. I was beginning to think you guys held something against me, I get **** in most of the posts I make here.

I've heard somewhere that you can not mix match the housings, ie FD front and T2 rear.... Unless you are going to match the front and rear housing (either FD's or T2).. Apprently due to slight tolarence difference between the housings.. And same goes with the rotors.
If I'm wrong please let me know.. I will correct the person who told me..
That's right. There is, as stated above, a hardness difference between 91 and 93, the older ones required a bit more OMP lubrication, 4 oil injectors instead of 2. You wouldnt want to use one FD and one FC housing because of this difference. There is no way to lube one more than the other, and it's even slightly possible that you'd get more wear in one chamber than the other (on apex seals) because of the hardness difference.

That said, I don't think there would be any REAL WORLD problems with using one and one. Most fd's arent daily driven and most dont even make it 50k at a time on an engine. This is the kind of thing that makes a difference at 100k, but not really by 50k or less. REgardless, I would shy away from it unless it was really necessary, i.e. the car had to be on the road asap, or the owner had no money, etc. Either use 2 of one or 2 of the other. This is true of the differences in 86-88 and 89-91 as well...I just dont like to mix series if at all possible.

Kevin, can you post information about swappng T2 rotors, ie; matching letters.
You can swap any 13b rotating assy for any other one. We'll assume you're keeping your eccentric shaft, those rarely wear out or tear up unless they saw an oil system failure or were abused. Other than that, the rotating assy consists of both rotors, the front counterweight that goes under the front cover, and the rear which can be a stock manual flywheel with integrated counterweight, an automatic rear counterweight for use with an aftermarket flywheel, or an automatic rear counterweight for use with the auto tranny. The only time you dont have to use all these parts from the same year/rotating assy is if you are having the parts balanced by a pro...in which case they PUT the parts into balance by shaving metal where necessary.

Obviously you would NEVER want to run different rotors...they need to match in compression ratio and weight. Here's the differences back to 84, that's the oldest that I've worked with.

-84-5 GSLSE 13b nonturbo, 9.4:1 CR, 11.5lb each, uses 3mm apex seals and thicker side seals than all 86+

-86-88 FC 13b nonturbo, 9.4:1 CR, 10.5lb each, uses 2mm apex seals and thinner side seals (same for all 86+, 2mm seals and thin sideseals)

-87-88 FC 13B turbo, 8.5:1 CR, 10.5lb each

Note that after 88, the rotors got lighter, but they also got weaker. Detonation can dent in the face of the 89+ rotors, so some prefer the older ones for their strengths.

-89-91 FC 13B nonturbo, 9.7:1 CR, 9.5lb each

-89-91 FC 13B turbo, 9.0:1 CR, 9.5lb each (this is the same as an REW, RE, or 20B motor)

Note that all rotors up to 93 used the same rotorbearings, with a shallow oil passage in the center. The later bearings had a thicker passage to retain a bit more oil, so this should be considered if building a performance engine, you may want to use the later bearings even if the originals were useable.

-93-95 13B-REW, -RE, 20B, 9.0:1 CR, 9.5lb

As far as rotor weightcodes/letters, it's simple. They are lettered A through E, each representing a different weight code. You want to stay within one letter of each other, such as C and D. IF you can get 2 of the same letter, that's the best balance you can obtain without getting a professional to rebalance. It could be said that rotors are balanced from the factory because of this.

For instance, if you were dealing with FD rotors, they're suposed to weigh right at 9.5lb with no bearing. An FD rotor with a weight code A might actually weigh 9.70lb, while a Fd rotor with a weight code E might weigh 9.30lb. Those are not actual numbers, but you get the idea. Mazda knew their manufacturing process wasn't perfect, so rotors had different weights. Their solution was to weigh them and mark them a certain range, so that the engines would be closely balanced to one another, for the best smoothness and power possible from a mass produced engine.

Oh, and if you've ever seen the circles drilled out on the sides of rotors randomly, that's how they balance each tip of the rotor. During their process, one tip may have settled with more material than another, so sometimes they had to drill material out so that one side wasn't heavier/more massive than the others.
RotaryResurrection is offline  
Old 09-21-04, 11:34 AM
  #13  
Banned. I got OWNED!!!
Thread Starter
 
Gargamel's Avatar
 
Join Date: Dec 2003
Location: The land of Lincoln
Posts: 1,783
Thanks: 0
Thanked 0 Times in 0 Posts
Thumbs up

There aren't many builders that will tell you their secrets.

Kevin, once again. You've out-done yourself.
Gargamel is offline  
Old 09-21-04, 11:45 AM
  #14  
Lives on the Forum

iTrader: (8)
 
RotaryResurrection's Avatar
 
Join Date: Oct 2003
Location: Morristown, TN (east of Knoxville)
Posts: 11,482
Thanks: 0
Thanked 1 Time in 1 Post
No secrets. I thought it was common knowledge. Changing rotors is no different than changing pistons in a v8 or something...rebalance it and go on. Or changing heads for different flow patterns..we change irons and rotorhousings instead.
RotaryResurrection is offline  
Old 09-21-04, 12:41 PM
  #15  
Eats, Sleeps, Dreams Rotary
10 Year Member
iTrader: (4)
 
BigIslandSevens's Avatar
 
Join Date: Apr 2003
Location: Denver, NC
Posts: 3,531
Thanks: 0
Thanked 0 Times in 0 Posts
Originally Posted by Gargamel
There aren't many builders that will tell you their secrets.

Kevin, once again. You've out-done yourself.
This isn't exactly gaurded knowledge. He isn't telling anything you can't find on the mazdatrix website or RB.

Or any decent rotory tuner book

Not slamming you Kevin...YOU PROVE YOU ARE GREAT BY TYPING BIG AND POWERFULLY
BigIslandSevens is offline  
Old 09-21-04, 01:01 PM
  #16  
Lives on the Forum

iTrader: (8)
 
RotaryResurrection's Avatar
 
Join Date: Oct 2003
Location: Morristown, TN (east of Knoxville)
Posts: 11,482
Thanks: 0
Thanked 1 Time in 1 Post
I type MAD QUICK y0!
RotaryResurrection is offline  
Old 09-21-04, 01:48 PM
  #17  
DGRR 2017 4/26-4/30, 2017
iTrader: (13)
 
Herblenny's Avatar
 
Join Date: Nov 2001
Location: Alabama
Posts: 13,597
Thanks: 0
Thanked 1 Time in 1 Post
Kevin,

Thanks for that info... Just wanted to make sure info I recieved it correct.
Thanks!

PHIL
Herblenny is offline  
Old 09-21-04, 04:56 PM
  #18  
Banned. I got OWNED!!!
Thread Starter
 
Gargamel's Avatar
 
Join Date: Dec 2003
Location: The land of Lincoln
Posts: 1,783
Thanks: 0
Thanked 0 Times in 0 Posts
Bump, for awesome info.
Gargamel is offline  
Old 09-22-04, 12:23 PM
  #19  
Banned. I got OWNED!!!
Thread Starter
 
Gargamel's Avatar
 
Join Date: Dec 2003
Location: The land of Lincoln
Posts: 1,783
Thanks: 0
Thanked 0 Times in 0 Posts
Gargamel is offline  
Old 12-06-04, 01:32 PM
  #20  
Forever Modified
10 Year Member
iTrader: (1)
 
lopedl's Avatar
 
Join Date: Dec 2003
Location: WA
Posts: 1,423
Thanks: 0
Thanked 0 Times in 0 Posts
It would be neat to see if any of the FE parts were interchangeable.
lopedl is offline  
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
pfsantos
Canadian Forum
9
10-19-15 07:04 PM
Don49
Race Car Tech
4
09-03-15 05:03 PM
Engine stand ready
Website-related Comments, Suggestions and Issues
2
08-28-15 11:59 PM


Thread Tools
Search this Thread
Quick Reply: So, it's possible to use 2nd gen N/A housings in our FD'S?


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.