Jeff20B

iTrader: (13)

Hey everyone. As some of you know, I have a 20B that needs to go into something. Two candidates are a GLC and an S model FB.

Qualifiers for each car are:

GLC Currently set up for a 13B.
GLC already had the 20B in it at one point so most of the mods are done.
Was too much engine for the car as I recall.
Ran hot but I think I know why now.

FB Currently set up for a 12A.
I've only driven it with a nice 12A ('74 spec intake ports, modded Nikki).
Handled great. Decent power.
Ran cool with the 12A and a beehive oil cooler with tall radiator.


Yes, the 20B was once in the GLC and it ran. It had a MegaSquirt that wasn't really tuned yet. It needed a rebuild so I'd like to rebuild it before it goes into anything. No point trying to tune around low compression.

So while the rebuild is in the works, I was going to build a 13B for the GLC and a 12A for the FB since each car is set up for that type of engine. Plus I need to drive each one to determine which would handle the extra power better (I'm sure you're already thinking the FB would do much better with the 20B, but you have to remember the GLC was already set up for the 20B and the header, tranny mount, wiring harness etc have already been constructed and worked, so it's kind of a toss up from my perspective).

The 13B was going to be a stock ported 4 port (yep another one). The 12A was going to be a copy of the nice one I tested in the FB with '74 spec intake ports, slightly enlarged exhaust ports and a modded Nikki.

Just for fun I was going to prep the 13B for a Camden SC because I have access to a 5" with a 13B manifold. This way if the 20B goes into the GLC, the 13B with Camden will go into the FB. Win win.

Thanks for reading this whole post. Please give me your honest opinion and remember the 20B already fits in the GLC and wouldn't require much to get it back in there. Just gotta drive 'em and see which one I like better I guess.

orion84gsl

iTrader: (5)

Although the GLC is set up, I think you should stick it in the FB, I could see it being alot more fun, albeit more work to get it in there. But as you said, you gotta see which you like more. Good luck

Jeff20B

iTrader: (13)

Thanks. You may be right about that. A lot of work went into getting the 20B in there the first time. Then a lot of work went into getting the 13B in there, not to mention all the finishing touches.

You can see what I'm talking about in this GLC thread.
https://www.rx7club.com/forum/showthread.php?t=626869

If I were to put the 20B back in, the exhaust system from the header back would need to be redone. If a 13B goes in, I won't need to change anything, and it will still probably end up to be too much engine. How about a Sterling carb on a stock ported 4 port 13B? Steve said his with a Yaw carb made like 170HP at the shaft at 7k. Eep!


Here is a thread for the other candidate.
https://www.rx7club.com/forum/showthread.php?t=691730

A total sleeper.

Jeff20B

iTrader: (13)

This is kind of a nice picture.



But then I look at the GLC 13B thread and I just cringe when I see how much work went into the exhaust alone. That was all done in RB thickwall pipe, folks. No crappy crush-bent thinwall aluminized garbage here... and it's still freakin' loud! Turns out one of the Rotary Engineering glass packs lost its internal packing. Fortunately it's the rearmost one and easily replaceable. I think I'll throw a Borla in there.

The tranny tunnel patch was probably the most tedious of all. Getting all the bends and curves right wasn't fun. I like mechanical stuff. Maybe I'm like Steve84gsTII; a little too left brained for my own good? Nah, Steve is great.

So the exhaust and tranny tunnel would have to be completely redone if I put the 20B back in. I didn't really enjoy it the first time around. Would I the second time? The exhaust was also wrapped in that fiberglass header wrap stuff. I don't really want to mess with it. I think I'll draw the line at handling the header during R&R of the engine. Itchies.

Well, I suppose a stock ported NA 4 port 13B can go in the GLC and I'll be happy. The SC was scheduled to go on a different engine anyway but could have easily gone onto this one, if it was going into the FB. There is not enough room in the GLC for an SC unless I want to cut into the strut tower.

The car is so light it really doesn't need the extra driveability and torque as much as something heavier like a rotary truck or whatever. Would you guys agree?

If the SC was a 7" I'd consider it on the 12A in the FB because Atkins makes a manifold for it, and it's harder to fit in an REPU since the 7" sticks out about an inch further right than the 5". There is no 5" 12A manifold so I'm stuck with it on a 4 port 13B.

orion84gsl

iTrader: (5)

Am I hearing this right? Your not going to do something just because a part isn't produced for it? Did you not modify a crossmember to fit an engine? I never thought you would give up so easily. If the part isn't available, make one.

Jeff20B

iTrader: (13)

To what do you refer?

PercentSevenC

The streetported 13B currently in the GLC is already too much for it. Even with the current tall-geared rear end, on cold days there's no traction at all until third gear (I've burned out through fourth on rainy days). Poor tires have something to do with this, but still, the GLC would need a modified GSL rear end at the very least. But if it could hook up, a 20B in a sub-2000 lb. car would be no joke.

Honestly, it could go either way as far as I'm concerned. Putting it in the RX-7 probably makes the most sense. But I admit I'd be more than a little tempted to stick it in the GLC, add forced induction, and go run low 10s. Especially when there's the option of a SC 13B for the FB.

Like you said, you'll really just need to drive both cars for a while and see which one feels right for the 20B.

diabolical1

iTrader: (3)

the GLC

Jeezus

iTrader: (4)

I got a soft spot for GLC's... 20b!

stilettoman

iTrader: (1)

Jeff - You may recall that I had a completely stock 13b in my GLC, and that I built up a rear axle assembly, using an RX-2 center section and GLC axle tubes, so that I could run a small-axle LSD. I also used 1st gen front struts and brakes. The only performance enhancement was the aluminum flywheel - I even ran the cast iron exhaust manifold. I drove that car for over 100,000 miles in four years, and I thought the power was perfect for the car. That chassis just does not justify anything more than about 150 HP, in my opinion. Put in enough power to keep up with the modern ricers, and you will never make it handle well. The FB is better, but still not the best.

Don't know if you saw Durkee's 20B powered 2nd gen with the supercharger, but it was pretty nice and he got a lot of money for it. It was really fast. The 2nd gen chassis is heavier, but it will handle the power a lot better. Personally, in your position, I would sell the wife and kids, and go find a clapped out FD to put the 20B in.

In case anyone wants to fab a rear axle like this, it was instructive to discover the RX-2 and GLC rear axles had the same width center section and the same diameter axle tubes. For aligning, I took a piece of straight pipe and wrapped it with electrical tape until it just fit inside the tubes at four points, two outboard and two in the center section. Simple, but it worked well.

orion84gsl

iTrader: (5)

This is what I was referring to.

1983GSP

http://youtube.com/watch?v=_s8deD0E-OE here ya go jeff, fb ftw

FirebirdSlayer666

iTrader: (3)

I have to say Jeff, it's probably better to put the 20B in the FB, just for the fact that I wouldn't want to have to redo things I've already done in the GLC. The hardest part about putting it in the FB would just be mounting it. Put a stronger drivetrain in with brakes and suspension and you'd be set. Like orion84gsl said, you could always make a custom plenum manifold for the 13B in the GLC so it moves the supercharger up and more over top of the motor instead of having to cut into the strut tower. Cut the hood instead! LOL. Or you could be real creative, give me the 20B and build a 12A 3 Rotor for the FB. LOL

Jozay721

hey jeff havent seen u in a while
yeah if i was in ur position id ut the 13b in the glc and put the 20b in the fb...although it would turn out good if u built the 13b and put it in the fb then put the 20b and put it in the glc....still 20b in the fb is just amazing....(drooling)...lol

Kerebrus

iTrader: (30)

All I can really say is, S model FTW.

FirebirdSlayer666

iTrader: (3)

+1. I own 2 now woot! LOL

Jeff20B

iTrader: (13)

orion84gsl, are you talking about this crossmember?

I modded this last year when I thought Iwas going to put the 20B in the white '83 GSL. That never happened so it is available for the S model.

You've always said a 20B in a 1st gen would be a good idea. I went back and looked at a few of my other 20B threads and you were there, encouraging me. Thanks.

Here is something I found that I wrote a few months ago concerning engine position in the engine bay, and why I doubt I'd move a tranny rearward again, like I did in the GLC to shoehorn the 20B into it.I also like the part about how the net weight gain for the whole car is 80 pounds, and relocating the battery to the storage bin helps spread the weight out a little better than concetrating it all in the engine bay. Of course there is also the exhuast and intake manifolds, but they don't weigh all that much more than 13B stuff.

PercentSevenC and I discussed the project at length and we both came to the same conclusion; each car must be driven in order to determine where the 20B should go. While the GLC has already been modified and could relatively easily go back to 20B status since I kept the header and other parts, the RX-7 would probably make a better project and I'd have more fun with it when finished. Plus doing the work should be fun; it's only when I don't feel like doing the work is when it actually feels like work. Putting the 20B back in the GLC would avoid some of this work since the header is already done, but it would make a lot of other work having to cut into the tranny tunnel and redo the entire exhaust system. He also looks forward to seeing how his turbo FB stacks up to an NA 20B FB. I kinda am too.

stilettoman, yes I recall that you had a stock 13B in your GLC and it ran for over 100k miles. That's really cool. As for performance parts if I choose to go with a 13B, I have a little 8 pound super light steel flywheel that weighs the same as aluminum or really close. Also the header has already been constructed and the carb will probably end up being a Sterling at some point since they do quite well on stock ported 4 port 13Bs. The Hitachis seem a little lackluster at high RPM so a stock venturi but otherwise modded Nikki will probably go on to tide me over until the Sterling since the primary venturis are 20mm, as are some Hitachis, but Sterlings are 24mm. Some Hitachis are 22mm, and they have noticebly better primary performance, however they still suffer from the lackluster high RPM performance which '81-'85 Nikkis apparently don't. I figure a Sterling will add icing to the cake.

As for the brakes and rear end, the fronts were upgraded to '80 vented rotors and calipers. The rearend may get upgraded at some point but it seems to be holding the power of the streetported 13B so it's a low priority. I like your solution to aligning the axle tubes.

The RX-7 struts were too short as you know, so I built some 2" lift spacers. Also a set of RB front springs went on. The driveability improved substantially. Now all it needs is a better muffler and a stereo or something. It's currently very loud inside and unpleasant on long trips.

1983GSP, that video helps. Thank you.

FirebirdSlayer666, I'm not going to bother with the supercharger in the GLC. A stock ported 13B 4 port will have plenty of low end torque and driveability, even for a light flywheel and a tall geared rearend. At least that's the theory. It does ok with the current streetported 13B although I'd like a little more low end. Plus it feels like the RB light steel flywheel is a little too heavy. The lighter one will be an improvement.

Jozay721, you might even say that since the GLC 20B project has already been done, why not go for the 20B FB project next?

Cbz, I'm starting to lean toward the 20B S model.

I think I had forgotten that it's about the work, and less about the finished project. If you don't enjoy what you're doing, you need to reevaluate why you're doing it. That's what I needed to do. This thread has helped quite a bit. Thanks everyone.

Jeff20B

iTrader: (13)

Ok guys, now for some more pictures.

The GLC 20B header.


The 20B itself with old school 13B 4 port pan that fit well in the GLC. Notice the '84-'85 FB front cover?


Really old picture.


Here is the modded crossmember in the white '83 GSL. It came out and in went a GSL-SE crossmember for Percent's turbo 13B project.


Here is the S model engine bay with the nice 12A in it. This setup convinced me to put the 20B in - not because it was gutless or anything, far from it - but because it drove so well with the decent power the 12A had, what with a modded Nikki, '74 ports and RB exhaust.


And finally the S model itself. Not much to look at, but that's good because it won't attract the wrong kind of attention.


Oh yeah, here is the RB exhaust. It blew lots of cool orange dust.

1983GSP

your welcome jeff, ill see if i can drag up some more.

1983GSP

http://youtube.com/watch?v=ymHwcJeFm7k

1983GSP

http://youtube.com/watch?v=Syw9g4phLOk

Jeff20B

iTrader: (13)

Yeah, I've seen those. Thanks. His car is pretty loud.

Jeff20B

iTrader: (13)

Now in case you haven't seen how nicely a 13B fits in the GLC, here is a picture.


Notice how well everything fits? It's accessible. Carb adjustments, slave cylinder, ignition, spark plugs, coolant, oil level. Everything was more difficult when the 20B was in it.

Jeff20B

iTrader: (13)

I'll let this thread run a little longer. Then I'll make my decision.

steve84GS TII

I dont think it really matters what engine the GLC ends up with Jeff,its gonna be fast enough to be dangerous.They are so light and small,and NOBODY would expect one to have more than 100HP anyways,partly because nobody knows what they are!

My old 78 was a terror on the road,and that was with a little V-6 making maybe 130-140HP.... and it was weighed down considerably by the very same. A 13B is half the weight and more HP,even the 20B probably cant touch my old engine for weight,but its easily double the HP+.My GLC is so many tin cans now,but Ill always have the memories,plus the V-6 lives on in my Samurai.
More pics of the forgotten RWD car that saved Mazda's bacon when it mattered.......