20B Single Turbo 3rd Gen RX-7

[TheDarkbeatz]

rx7 is the best Japan car

[CruelSkies]

Don't know how everyone's gettting the mileage figures they are. I average 120 miles a tank. But I do drive it the way it insists!

[noe30594]

i noe this engine puts out alot of power but what did u do about the tranmission did u leave the stock 5 speed tranny

[aaroncake]

The car was built by RotorSports Racing and they used the stock FD transmission.

[ajfreshkid]

wat does 20b stand for

[aaroncake]

The 20B is Mazda's 3 rotor engine, based on 13B geometry. The "20" means two litre, the B is to indicate it is the 2nd generation 3 rotor. Actually that's a bit inaccurate since there was no 20A and the 20B is based a bit on the 13G. But at the time Mazda was playing a bit with designations. The full name of the 20B is "20B-REW". "REW" stands for "double turbocharger" in Japanese.

[Advandestromath]

Well since each rotor has a displacement of 0.654 liter, you have:

2 rotor x 0.654 = 1.3 so you get a 13B

3 rotor x 0.654 = 1.96 ( rounded off to 2.0) so you get a 20B

4 rotor, 2.6 = 26B you get the idea.

[Tj1056]

@aaroncake I thought it was 20b-re? 

[aaroncake]

@Tj1056 From the factory it is 20B-REW.

[Tj1056]

@aaroncake aww ok its the 13b that is re

[aaroncake]

@Tj1056 The twin turbo 13B found in the 3rd gen RX-7 is the 13B-REW. The twin turbo 13B found in the Cosmo is also an "REW" Rotary Engine (W)Double turbocharger, but is generally referred to as the "RE" since that is what it says on the intake manifold and to distinguish it from the 3rd gen REW.

[Tj1056]

@aaroncake you see the 13b-re on the 2nd generation am i wrong?

[aaroncake]

@Tj1056 The 2nd gen engine is generally refferred to by Mazda as "13B-DEI", "13B-EGI", "13B RESI" or a few other terms. On the forums, people just call it the "13B NA/6 port" for NA or "13BT" for the turbo model.

[Tj1056]

@aaroncake I know I have seen a RE model on a manifold for the rotary before :/

[aaroncake]

@Tj1056 Yes, that would be the twin turbo 13B from the Cosmo.

[Tj1056]

@aaroncake mmmhm ok :p well still 13b model lol ok thank you

[rm125madman]

stock fd3s gearbox can handle up 2 600hp, just need a good heavy duty clutch

[qualy55]

whats the mpg on a 20b?

[aaroncake]

Depends on how it's driven. 15-17 MPG around town, 22-25 MPG on the highway.

[JeefCakes]

With doing short journeys in mine (10 minute commute), without going on boost, and without going over 3,000rpm, I get 125 miles, from full tank, to the needle on top part of E.

IS THIS NORMAL? :D

[aaroncake]

Holy crap! My bridgeport gets better mileage then that. What A/F ratios are you running?

[JeefCakes]

On a good run it's not so bad, it's just the first 10 minutes seem to drink fuel as it's warming up.

Have you ever run your bridgeport on 4 10 minute journeys a day? If it gets better than me, then I'm going to cry.

[aaroncake]

I think you might have to cry. :-) I use my car to make service calls all the time and often make a lot of short trips in one day. I'm at about 200 miles per tank in the city.

[adiomang]

@aaroncake I know what you mean by the 200 miles per tank in the city... But it's worth every mile haha

[Tj1056]

@aaroncake damn thats better then my 13b :/

[1SBD1]

depends on how its modified and tuned. even std they drink more than your average V8.

[musclekid13]

@1SBD1 So true. I did the V8 swap and expected about the same for gas mileage. I'm actually getting better with my SBC and carb set up haha. Much respect for the rotary. I love it. Just didn't have money for it.

[FdSnakeEater]

couldve helped if it was actually longer than 10 secs. I blinked and it was already over.

[aaroncake]

Sorry, 10 seconds is all my old camera would record.

[noob5000000]

If it takes you 10 seconds to blink, you might want to go to the doctor or something.

[FdSnakeEater]

Umm...I was being a little sarcastic with my comment....what I meant was 10 seconds is too short. I thought it would be better if it was longer like a minute or something.

[yourayour]

There are a few local 20b fds around my area and damn are they loud and not to mention fast. Walk the built 2jz no problem

[rotorg33k]

That is HOT! love it!!

well done to all involved!! :)

cheers

Rotorg33k

[fubaloko]

This engine use FD's transmission?????

[aaroncake]

Yes, you can use the FD transmission. It bolts right up to the 20B, but because all 20B cars were automatic you need to swap the flexplate to an aftermarket light flywheel (to match the front counterweight) and of course get the clutch disc and pressure plate.

[fubaloko]

Thanks!!!

[SagaraSouske]

how much was this project?

[fubaloko]

this is 13b transmission?

[finaggo]

nice 20b but it run to smooth,got to have that brap,to make it the bad a--.

[TheGreenSmoke]

Can you still buy these rotary engines?

[aaroncake]

Yes, rather easily.

[mrpeepswoot07]

like the 20b

[yadid]

How much did it cost you for the 20b swap ???

[aaroncake]

Not my car. See the description that says it's RotorSports Racing. I don't really like FDs.

[v8killa09]

why dont you like FD's its a car that i could stare at for days and never get tired of it. please explain

[aaroncake]

I've never really liked the look of most FDs. Far too round and organic. In pure black they look decent though. Also one of the most unreliable cars ever made, with an interior that likes to crack after a few years and major maintenance issues (the fuel filter is mounted above the diff, for example...spark plug changes are a 3 hour process...).

[v8killa09]

3 hours to change plugs. huh i can change mine in less that 10 mins when the car is hot. and the interior is made great it depends how you take care of it, if you treat it like hell it will break fast like any car same with them being unreliable it all depends how you take care of it.

[aaroncake]

OK, I guess if you have to change them enough and have a lot of practice, it won't take 3 hours (which I admit, was a bit of an exaggeration). Looks like it would be a lot easier to do from below. The bulk of this comment will be continued below as another reply.

[nicklingi]

Most unreliable car ever made...are you on crack? The engine needs a rebuid every 40k miles and you need to keep topping up the oil but the rotary engines are tonnes more reliable than piston powered engines (hence why they are used in so many aircraft engines) and who the hell told you that you need 3 hours to change sparks? are you trying to remove them with your teeth? seriously dude, research a bit before you start sprouting shit!

[aaroncake]

The rotary itself is highly reliable. In the case of the FD, it's all the stuff that's bolted to it that lets it down. Turbos that often fail before 50K, and by that time they don't work properly anyway because the 70+ vacuum lines associated with the sequential system have baked and are leaking. AST tanks that like to explode, ignition coils that are weak and fail as they warm up, plastic intercooler pipes that once hot expand under boost.

[aaroncake]

Continuing, the cooling system is massivly underbuilt (ever notice how the cooling fan continues to run after the car is shut off? This is Mazda's stop gap to combat heat soak) for the power output of the engine. The intercooler is tiny, and the oil cooler is smaller then the FC (though the R1 had dual coolers). We won't even get into the crappy speed density ECU that will run the car lean with just an exhaust upgrade.

[aaroncake]

Oh, and of course the turbos are prone to boost spiking due to undersized wastegates. Speaking of that, what's with the fact that a *twin turbo* car doesn't have a factory boost gauge? What in the hell was Mazda thinking on that? Then there's the mysterious 3000 RPM stumble that can be almost impossible to track down in some cases. The 5th gear syncro likes to die on early cars, and those same cars have flaking paint due to issues with adherence to the primer.

[aaroncake]

Also many FDs have broken passenger door handle for some reason. Odd that a handle used much less then the drivers would so easily break.

I don't think I need to go on, but I can, and for quite a while. I do happen to have more then a little rotary experience under my belt. Take a look at my other videos (specifically those involving "Tina") for some examples.

[cody1413]

any cars intercooler continues to run...my moms mercedes continues to run once the cars off, if its hot....and rotarie engines are the HOTTEST running engine out there...and they are also the hardest engine to blow....you can redline that thing for hours...so please before you start posting things that you heard from some guy...GET YOUR FACTS STRAIGHT.

[aaroncake]

An intercooler, being nothing but a series of tubes with fins, really has no choice but to "continue to run" as it has no mechanical moving parts. I guess if you wanted to get very technical, you could say that as long as there is no heat transfer taking place (ie. interior temp same as ambient) then it's not "running", but that's a serious stretch. But if you are referring to the cooling fan, very few cars do this. Certainly very few when the FD was released.

[aaroncake]

Mazda continued to run the fan after the car was turned off as a stopgap measure when they noticed the major issues with heat soak. This is caused mainly by the massive turbo assembly and the fact that the precat is mounted up in the engine bay. Both totally bake the hoses in the area, which is also a major component to the unreliability of the sequential turbos. This info can be found in the book "RX-7" by Jack Yamaguchi.

[aaroncake]

As for the rotary being the hottest engine out there, that's simply not true. RX-7s run at the thermostat temp of about 86 degrees (varies per year), which is right in line with other engines of the era. Rotary cars tend to have large cooling systems for their displacement because there rotary rejects more heat into the cooling system. Unlike piston engines in which the cylinder, head and piston are cooled by the incoming fuel charge, the "hot side" of the rotary (spark plug area) is only...

[aaroncake]

...cooled by the coolant. The "cold side" (near the intake ports) stays cooler naturally. In fact if you split apart the keg, you can see the massive difference in cooling passages between those two areas. Many passages around the plugs, far fewer around the intake ports. Another hot spot is the bottom of the engine where you will see even more cooling passages.

[aaroncake]

Only oil can cool the inside of the rotors, which is why there is a large oil cooler as well. Some 1st gen RX-7s had a small oil to water cooler under the oil filter, referred to as the "beehive" by owners. It was ineffective so Mazda switched back to a front mounted air to water unit that they had used on previous rotary cars.

[rotor13]

@cody1413 what the fuck are you talking about?

[cody1413]

do you have a mazda Rx-7? cause it doesnt sound like you know much

[aaroncake]

Well, I drove my 392 RWHP (about 430HP at the engine) 2nd gen to work today. I also have a '84 GSL-SE, and a '76 RX-7 Cosmo. In the past I've owned a '78 RX-7 GS and an '86 GS. Note I have not owned an FD, mainly for the reasons I have already mentioned. Google "aaroncake rx-7" for an idea of how much I "don't now" about RX-7s. Take a look at the first two hits.

[zak302]

rx-7 sells 3mm and 2mm rotary motors... the higher hp one will run about 3,400...

[aaroncake]

The cost of a 20B engine is somewhat higher then a 13B, and then there's the 20K-30K of other stuff you need to actually install it...

[cody1413]

WRONG AGAIN.....the 20B engine is about 5k used and that come with everything...gosh your REALLY STARTING TO PISS ME OFF

[aaroncake]

The fact that a 20B comes with "everything" is pointless. The ECU from the Eunos Cosmo needs to see it's automatic transmission or it goes into limp mode. Some have had success fooling the ECU but seriously, why would you want to? Just install a standalone like you should and be done with it. However that's only a tiny part of the project. The 20B mounts do not line up with the 13B REW in the FD. In fact, you need to build an entirely new subframe to mount it or move the steering rack...

[aaroncake]

The issue with moving the steering rack is that it induces bump steer which really damages the handling of the car. Once the engine is mounted you'll need to significantly upgrade the cooling system (think the rad that is undersized for a 13B will handle a 20B? Not a chance). A single turbo conversion is required, otherwise you need to run the stock twins in parallel. The car will need an upgraded fuel pump, and you'll need to swap to larger injectors on the 20B.

[aaroncake]

Ignition is a bit of a deal as well. You'll need to either run 6 individual coils (so you'll need an ECU with the appropriate number of outputs) or you'll need to run waste spark on the first two rotors. Almost any ECU could run the 20B leadings only but why would you need that? FC trailing coils are commonly used on FC leading ignitors as a low cost option, but you still need something to control them.

[aaroncake]

Of course, you'll need to upgrade the intercooler as the stock FD IC is way too small (even for the stock FD). Add that single turbo conversion (do you have any idea the cost of a 20B T4 or T5 turbo manifold?) since no one would run the stock twins. An appropriately sized aftermarket turbo would be the GT40R (or bigger), T70 (or bigger), etc. Not cheap units.

[aaroncake]

Hm, what am I missing...Flywheel and clutch, oil coolers and lines, fuel lines, gauges, battery relocation, all other misc. wiring, misc. plumbing, some nice big tires to actually get that power to the ground, tuning time, a rebuild on the 20B (try doing that cheaply), all that custom intercooler piping, custom downpipe and exhaust, and then whatever else I may be forgetting. It is a large amount of work to put a 20B into an FD, FC, SA/FB.

[aaroncake]

To even suggest that the 20B "come with everything" shows how much you don't know. I'd appreciate if you stopped posting these ridiculous comments to my video as I don't enjoy spending my time to correct your misinformation. Of course, I think for now on I'll just remove them instead.

[Mutaku]

Seriously don't argue with aaroncake, chances are he does know a lot more than you. I'd like to mention that his RX-7 is actually going to be/ is featured in a book if I am not mistaken.

[adamrocque]

boring

[vkotis]

LOL...hahaha