K before anyone gives me slack for this. Ive already gotten some from turbo owners. Well Ive been really wanting to do the swap but never really knew how I could run the intake other than a carb. I was on ebay and came across one of these..
http://www.tweakit.net/throttle_body..._throttles.htm
Now the only prob with this perticular intake is the manifold, is being set up for a pref. port. I know a manifold for the stock intake ports could be fabed up so It would work out well. Well after seeing this I looked for any N/A 3 rotor engines that were out there. I came across
http://cp_www.tripod.com/rotary/
And found some usefull info on 3 rotor engines. I knew mazda campagned 3 rotors in ISMA and other racing sanctions but even up till a few years ago you could get a 20B race engine from Mazdaspeed( for a cool $20K). Well anyways I dunno if anyone has done this but I really want to try it. My recently rebuilt motor is loosing a coolant seal I think, so I rather just part it out and get as much cash as I can. My shopping list so far is.

1. 20B short block(use block off plates for emmisons, and rip off OMP and use premix, FD water pump housing and alternator)
2. fc3s.org or kdr motor mounts
3. Turbo II drivetrain
4. stock flywheel or lightweight steel
5. heavy duty clutch
6. stand alone EFI
7. tweak it IDA kit
8. 720cc injectors
9. intake manifold
Now here is the part most might says inst worth it but
10. LS1 electric airpump
11. exhaust manifold(similar to the ones used on the N/A motors to be lil more streetable) I would like it to be able to mount up to my BoNEZ high flow cat so the thing could be semi emmison compliant.
12. MDS ignition and coils and mount it ontop of the block similar to how the R26B looks
I already am using a koyo rad and FAL fan and would just remount it a bit more forward. Ive alsoread up on the front sway bar prob and would have to adress this. Just been thinking that the best way to get power from an N/A motor without bridge porting is a 20B. The swap isnt cheap I know but I have ALOT of crap to sell and have some money set aside. Just with not using turbso I dont have to worry about things like turbos, intercoolers, manifolds and what not. That cuts out like $5,000worth of stuff right there. With the IDA kit Id lose out on lower end power but I figure the extra .7L will help in that area. Figuring with using 9.7:1 rotors and a big streetport 320BHP and 400ft lbs tourqe. This is just from reading stuff online. Just would be so awsome to have an N/A motor that ate FDs for lunch not to mentioned laughed at V8's. LOL Im very long winded. Any feedback from FC people with 20Bs is welcomed. I know some might think this is stupid but its about the closest thing to a street version 787B you can get without making a 4 rotor.
Thanks!
-Stew

 

If you are trying to save money, you are making two mistakes:
1) A stock 20B-REW with turbos is generally cheaper than a custom NA engine.
2) There is nothing cheap about a 20B conversion.

Let's look at the engine options (prices and hp estimated):

1) Stock 20B-REW
$3,000 Engine
- $0 6x550cc injectors good for close to 400bhp turbocharged
- $0 intake manifold
$300 Custom Downpipe
$1,200 Intercooler & Plumbing
Total = $4,500 for about 400hp

2) Cheap NA 20B
$3,000 Engine
- $0 6x550cc injectors good for about 450bhp NA
- $0 intake manifold
$1,200 Custom Headers
Total = $4,200 for about 200bhp

3) Your NA 20B
$3,000 Engine
$1,068 Intake Manifold
$4,000 Rebuild, Porting, 9.7 Rotors
$1,110 6x720cc injectors good for about 600hp NA (ie overkill)
$1,200 Custom Headers
Total = $10,378 for your claimed 320bhp

The rest of the usual 20B swap mods and parts are still required regardless of the engine configuration. Don't forget about the required upgrades to the fuel and cooling systems. See the site below.
http://fc3spro.com/TECH/SWAP/COSMO/20b.html

Not by my math. Please explain.

 

An FMIC doesn't cost $5000.

 

Ok well I sorta expected this kind of repsonse. Well for one thing I got my HP numbers from the craig website not just of the top of my head. But if you think a S5 N/A motor with a stock port, IDA kit, exhuast you could make prob 220HP. So your-
Cheap NA 20B
$3,000 Engine
- $0 6x550cc injectors good for about 450bhp NA
- $0 intake manifold
$1,200 Custom Headers
Total = $4,200 for about 200bhp
How would a 3 rotor only make 200BHP, and a 2 rotor make 220? The way I was getting the higher numbers was with using the IDA kit. Im not sure how a header would cost $1,200, I know plenty of people who can fab this up for a fraction of that price. So the price you have would prob be the same but I think the HP# would be close to 300 or more. For the fuel system I have most of that taken care of, as well Im running a Koyo alum rad and a FAL fan so cooling is not a issue. I dont mean to start a **** storm just something that would be really sweet to do. Hell RE Amemiya uses a 20B in there yellow JGTC GT300 car. Now that runs a perf. port and is tuned by RE so If they are doing it and Mazda did it for how long it cant be that stupid of and idea.
-Stew
P.S I didnt mean the FMIC would be $5,000 but a FMIC, DP, mid pipe, and all the other related turbo crap.

 

Ok well I sorta expected this kind of repsonse. Well for one thing I got my HP numbers from the craig website not just of the top of my head. But if you think a S5 N/A motor with a stock port, IDA kit, exhuast you could make prob 220HP. So your-
Cheap NA 20B
$3,000 Engine
- $0 6x550cc injectors good for about 450bhp NA
- $0 intake manifold
$1,200 Custom Headers
Total = $4,200 for about 200bhp
How would a 3 rotor only make 200BHP, and a 2 rotor make 220? The way I was getting the higher numbers was with using the IDA kit. Im not sure how a header would cost $1,200, I know plenty of people who can fab this up for a fraction of that price. So the price you have would prob be the same but I think the HP# would be close to 300 or more. For the fuel system I have most of that taken care of, as well Im running a Koyo alum rad and a FAL fan so cooling is not a issue. I dont mean to start a **** storm just something that would be really sweet to do. Hell RE Amemiya uses a 20B in there yellow JGTC GT300 car. Now that runs a perf. port and is tuned by RE so If they are doing it and Mazda did it for how long it cant be that stupid of and idea.
-Stew
P.S I didnt mean the FMIC would be $5,000 but a FMIC, DP, mid pipe, and all the other related turbo crap.

 

I don't know what the big deal is...just do it.


-Ted

 

I know some day i will do a n/a 3 rotor install in something, i am sure it will be fine and low cost.
but a rebuild with high comp rotors will be needed
to make any hp.
now where to find 3 good high comp rotors cheap.

matt

 

 

We might have an NA 20B in the works, but I dunno if the owner still wants to do this.  We'll see when he comes back from a trip in a couple weeks or so...

The plan is to grab the 20B flange from Racing Beat.  We're also going to buy a bunch of u and j bends from Racing Beat, as this stuff is 0.120" wall - it'll handle the rotary heat no problem.  After that, it's just a matter or getting the header welded together.  We're still working on final configuration of the exhaust, but we're leaning on a 3-into-1 header into a single 3" exhaust system.  We're going to keep the stock 20B intake and TB for now, but we could rework the induction system later.  Control will be handled by a Haltech E6K for now.

Simple and effective...we'll see what kinda power we can get this set-up to produce.  The car is a purpose-built drift competition vehicle, so we're shooting for broad torque band.


-Ted

 

Hey Ted, that sounds like a good plan.

I built a 3 into 1 header with the RB/Mazdatrix flange. It'll go into a single 2 1/2" exhaust system.

 

Here it is in the car.

 

Wow, that's a super compact header design!  How long did it take to get the bends to fit that way???


-Ted

 

a VERY long time. This was my first header. It took me a long time to get all the bends just right.

It was a used RB 12A header in decent shape. Somebody ovaled the holes to make it fit a 13B. The rear pipe was also dented inward to clear the idler arm. I cut off the flange and dented section and carefully fitted some U bend pieces (like the RB type you mentioned above). Then added a third pipe where the two collect. The collector output is only 2", so I'm going cut it off and add a short length of 2 1/2" with a flange on the end.

I have more pics, all black and white. You're seeing the only color one I 'built' from three filtered B&W pics.

If I had to do it all over again, I'd cut the dented pipe even lower and make the header even more compact so it would be further from the bellhousing.

 

and people made fun of my welds when they seen them

matt

 

Yeah, they're beautiful. You should see the 1024 x 768 version. There's no hiding the lumpy beads at that size.

 

Jeff20B
That looks really nice. Any way you could reproduce it? How long does the piping run down under the firewall? Using the stock TB and intake manifolds woudl seem like a better way to start out. Makes it cheaper than using the IDA kit.
-Stew

 

Yeah, I tried not to comment on it, since I don't do my own welding myself.

If it doesn't leak, that's good enough!


-Ted

 

I don't know if there's a feud going on between this forum and others, but if you'd like to see more pics of the header and engine bay, click here.