I've been planning on purchasing a 3rd gen for a while, then I got this crazy idea the other day. Put a bridge ported 20B into my fc.

Anyone here run a non-turbo 20B? I was thinking I could do this a little easier than the turbo route.

What I am missing from this list?

20B rebuilt w/ a BP and S5 n/a rotors
Aluminum Radiator
Motor Mounts
Three Carbs
Intake Manifold
Header
Oil Lines
Fuel Pump
Block Off Plates
Premix

Anyone here run a setup like this? Any compromises? What power do you think this type of setup would make? Worth it, not worth it?

 

So let me get this straight, you want to pull the stock turbos and fuel injection off a 20B-REW that is good for over 400hp (550hp with street porting), and replace it with a custom intake manifold and outdated carburetor setup that will make half as much hp at twice the noise level and will take more time and money than simply using a standalone EMS?

Generic build list here:
http://fc3spro.com/TECH/SWAP/COSMO/20b.html

 

Oh I totally forgot my main question! I was wondering if there was a distributor available for the engine, or would I just have to go standalone/ECU anyway?

I figured with the 20B n/a setup it would be twice as reliable and if not twice as easy to tune. I downloaded a vid the other day of one reving with just a downpipe and I was in love.

 

dude ...not to sound like an *** , but why would you wanna do that ???
the engine IS reliable as long as you dont do something stupid

 

N/A engines run all day long on cheap gas and they won't frag themselves when you get a crappy tank.

 

why in the world would you go to the trouble (and money) of putting a 20b in youre car and run cheap (crappy) gas ????

 

Because there is hardly any worrie about detonation with lower grade gas on a n/a engine.

 

It is only three seconds but it is N/A. You may PM him to ask more questions. As it seems most are against your idea. Which is a even BETTER reason for you to do it !!

I agree totally with the reliability and less worry factor with n/a engines. And I also agree that to make the power to make the car as fun as it would be WITH turbos, will take a fair chunk of $$. But that should not stop you if you want to do it. Hell I believe for the last few years at least the JGTC FD's had to run a 20b n/a. I think it was PP. I think the rules have changed last year or this year about the engines the FD's are aloud to run.Hope that helps encourage you to do it!

https://www.rx7club.com/showthread.p...hreadid=291793

 

I say do it! A lot of aircraft guys run streeported 20B's with bulleproof reliability. I know a good engine builder who can build this engine...PM me for details. Oh, and scratch the carbs and distributor. Go with a Haltech E11 of Microtech LTX12. You should be looking at around 430BHP. Up around 500BHP if you go with a P-Port.

http://www.autospeed.com/cms/A_0615/article.html

-Hakan

 

Actually, a better option might be a street-ported 20B. Skip Gorman (of KD Rotary) was running mid-12's with a non-ported 20B w/o turbos and with a 4.33 ring & pinion. The stock port of the 20B is smaller then a 13B-REW so it stand to reason that street-ported 20B would make around 340HP and be good for low twelves, maybe even 11's.

 

The Stock fuel system on a 20B is truly good for 550 h.p.? that is amazing, considering a stock 20B makes 300 h.p.

 

The stock injectors are only good for about 400bhp, but the the stock manifolds, throttle body, turbos, and engine internals are good for 550bhp in street port configuration. See the Pettit Banzai here:
http://www.iluvmyrx7.com/3rdgen/arti...1198/index.htm

 

hmm, thats sounds more like it... that car was made in 1998? I know in 1996 the 20B's engine MSRP was like $20,000 dollars. in 98 it would still be around that price right?

sorry for the minor hijacking

 

whoa! 340 on just a street port all the better reason to bridge port it! I am liking this idea more and more. In the end, this will be such a fun drag car.

Thanks for the input guys, another question though.
Why fuel injection over Carb? It seems less restricting, less electrical load, less weight, easier to tune, and lastly affordable.

 

Don't quote me on that.

Well, whether carbs are easier to tune or not is subjective (personally I think EFI is easier.). Also carbs will be A LOT more expensive. Think about it you'll need: -manifold ($700)
-triple barrel carb ($700)
-custom fuel lines ($100)
-custom intake ($?)

The RB kit for 13B's runs ~$900. Obviously, a 3-rotor would be considerably more. With that amount of money you can get a Microtech LT12 and have enough to get it professionally tuned. If you want more on carb versus EFI check this out:
http://www.twminduction.com/ThrottleBody/carb_vs_fi.pdf

Written by Jim Mederer of Racing Beat.

 

Restriction: So what is another word for "venturi"?

Electrical Load: The 20B alternator is much better than the FC alternator. The JC Cosmo Type-E CCS came stock with more electrical junk than most of the teenagers nowadays put in their cars, and it worked just fine. However, if you are building a race car that has no electrical system, then yes, a carb setup is easier to deal with than a custom mechanical FI system.

Weight: I'm pretty sure that 3 carbs weigh more than 6 fuel injectors/rails and a standalone EMS, but if not, the weight would not affect the car's performance by a perceptible amount.

Easier to Tune: The carbs are probably easier to tune poorly, but an EMS is going to be much easier to tune well.

Affordable: I wish I had a dollar for every post on this forum where somebody comes up with the great idea of building an NA 20B because it would be so "affordable". There is nothing cheap about installing a 20B in your car. If you want an NA for whatever reason, then that's fine, but reality dictates that this project is going to be expensive. So far the number of people on this forum who have actually built an "affordable" NA 20B is zero. If you build it well, it will be expensive.

Bottom Line: Do what you like, it is your car.

 

You need to do more research on this matter yourself.

Wrong.

True, but why would you care?
The stock Cosmo alternator is already on the 100A range, and you're running way less electronics than a Cosmo.

This may or may not be true, but again, why would you care?
Does an extra pound or two in the engine bay really make a difference for you?

This is relative to the tuner.

Again, relative to the buyer...
In the long run, the EFI set-up will have better gas mileage.
With the engine being such a gas guzzler, the increased mileage will be significant in the long run.


-Ted

 

Define "affordable"?

So far...
$3k engine
$1k Haltech E6K
$350 MSD DIS-4
$250 upgrade radiator
$1000 OS Giken triple-plate clutch (overkill for NA )
$600 custom exhaust + 2 mufflers

Add a little more for miscellaneous stuff (spark plug wires, etc.), it's still under $6k (eliminating the overkill clutch) and it's running!

As a short update, our MSD DIS-4 was firing rotor 1 intermittently and all three leading spark plugs were loose.  DOH  That explains the low power.  We blew a 1" chunk of gasket off the header flange, so we need to fix that too.  Hopefully we'll get to return everything in proper order this time!


-Ted

 

is the fd alternator any good ???......can i use this on my 20b???

 

If you insist on the FD alternator, I'd recommend using the FD water pump housing and FD water pump.

You'll need to swap the studs on the front iron, since the FD stuff uses the longer studs.

But, they all fit...and you can use the FD pulley set.

The downside?  The FD stuff adds a couple of inches up front, which can be a pain in the *** for clearance.

The FD alternator *may* just swap in, and swapping the Cosmo pulley might make it a drop-in affair?


-Ted

 

j9fd3s once said the Cosmo alternator has a snout. Does it have a longer shaft than the FD alt? Or was it just a pulley difference? I think it was just the pulley. 7pk to 5pk or something like that.

 

i have my fd alternator in , i am just wondering if it can supply for the engine ???...

 

Hehehe, good point. What I mean is building an NA 20B at a significant savings vs. simply installing a good, used, stock 20B-REW. My main problem is that some newbies are sometimes under the misconception that since they cannot afford a 20B-REW swap, then maybe they could afford a NA 20B swap. I just don't want anybody to actually attempt a project that I know is going to cost more than they think. Add the usual desired go-fast goodies, such as porting, S5 NA rotors, balancing, light flywheel, dry oil sump, competition water pump, etc., and the price can get pretty steep. I think that most people don't realize that the 475hp 3-rotor engines of 80's race fame carried a $42,000 price tag.

Your project seems to be pretty close to the cost of installing a stock 20B-REW.

BTW, for those reading RETed's list, he did not mention a lot of parts required in the swap, so please don't take that to mean his parts list was all-inclusive. See RETed's website for more details.

 

Ah!  That explains it!
Yes, you're right.
We only went this route to get some good data on tuning the NA side of the engine running.  From my experience, this makes for a really nice (turbo) tuning when running on the street, as all the vacuum ranges are running almost optimized.

The project WILL go turbo, once the budget is all sorta out.


-Ted

 

After a little brainstorming, another idea clicked....Toss in some S4 or S5 irons and make an 8-port!! Might be tough but worth a shot...Then again, I think one of the intermediate housings on the 20B is smaller then a 13B's intermediate housing.

~Hakan