700hp 13b internals
 

Hey im a new to the Rx7 world and i'm looking to build a 700hp RX7 to use on the track and street once a week or so. Im wondering what kind of upgrades to the internals I should look for? Ive been a muscle car guy all my life so the information i heard on RX7s wasn't exactly the most accurate. (When I say internals i'm referring to the rotors, crankshaft, and housing). I hear that if you get a low millage block on the 13b and get an aftermarket crankshaft 550-700hp is an attainable goal. And one last question. So this guy ive been hanging around has the coolest LS swaped RX7 that he uses 2 tunes on. One runs the motor using 7psi for the street and the other at 15psi for racing. Is he just yanking my chain or is this possible? If so how could I replicate this on my build?

There really are no upgrades, you use the stuff Mazda built. There are not really any aftermarket parts anyway. Guru used to make a three bearing eccentric shaft, but this was more for naturally aspirated engines spinning at super high RPM, like 12k+(And I understand that they are really more trouble than they are worth)

Thanks man! so your saying that stock internals will let me reach my goal? And im afraid im not looking for RPMS higher then 9.5K :) if theres one thing ive learned from nitrous RPMs without a large budget blow motors

Well you are going to need to port it to reach those goals.

But most of the work will come from the supporting parts - turbo, intercooler, ignition, fuel system etc etc

Lots of good information here, especially if you look through some of the high horsepower build threads.

Get to 400whp reliably first, learn to drive that before you try for more.

The cost to make and maintain hp goes up exponentially above that.

You figured everything else and you are down to the amount of boost on the street vs the track...
dont you just love when the 10year olds get ahold of a pc.. !!!

Reread it... a friend of his has an LS swapped car that has two tunes in it. I've never experienced 15psi in an LS-anything, but I can tell you that 11psi in a 413ci LS2-based engine is pretty stupid for power :)

This is very doable with many ECUs. I know Megasquirt can do it. I have also done a few FAST XFI installations with a "clicker switch" that can switch between four different tunes. We would usually set them up for anti-theft (null tune, vehicle will not run), valet (will not go over 2500), low boost, and high boost.

Given how the higher level Megasquirts can do map blending based off of ethanol content, it's very easy to make a super low boost tune and a super high boost tune and use a knob on the dash to have infinite adjustability between the two by using a simple potentiometer to vary the "ethanol sensor" input's voltage. Obviously you would not be able to actually DO a multifuel tune with this setup, but jeez the computers are cheap, compomises have to be made...

I thought pretty much everyone with a turbo and programable ecu had at least two boost settings since the day these technologies were available to the public back in 1873?
tune for the higher boost setting and then simply turn the boost down?
15psi LS would be bonkers though haha.
also, 700rwhp two rotor would probably want at least some nice pins and extensive machining to be half reliable.

The statement that there are only really Mazda OEM parts is untrue. There are a number of manufacturers in Australia and New Zealand making billet machined side/centre plates, rotor housings and e-shafts (PAC Performance, ProMaz, PPRE, BilletBoss etc etc). They have been around for years and are used on many of the 7 second and faster cars.

That said, they are not needed at the 700hp level...But as WANKfactor correctly point out, you would want studs/dowels and all the usual internal modifications/machining/clearancing etc at this level.

gia sou re kypreo!!!!!

It's all shit, though. None of it is measurably better for performance or reliability than the stuff Mazda built.

This isn't saying Mazda Uber Alles, it's more of a lament that the aftermarket always sucks. The piston engine aftermarket produces some good stuff, if you have a machine shop at your disposal to finish up what they were too cheap to do before selling product. Rotary wise, there's.... nothing.

^ yeah you will be using mazda components, but dont think you are going to win the lottery on an unopened block with 700hp every time either. It will need more than ports. It will need significant strengthening, balancing and other tweaks. To the op, in other words $$$$$ and even then you will likely be blowing motors or at least rebuilding regularly. Then you have transmission woes. There is no Mazda transmission that will happily take 700hp. 700hp is getting toward the ragged edge for these motors and probably not a great idea as an introduction to the rotary world and a streetcar unless you like building engines a lot. 400hp happy as larry.
700hp LS makes more sense.

at 19, can u even afford such a thing? i think it's more about bragging rights. and have it wrapped around a tree in no time.

Shit howd u know I was 19? And yeah I can afford it im living with my mom to save $$ and I have a full time job as a HVAC repairman. My budget is 10K-15K. Any advice? Is my goal to large for my budget? and ill try to be careful off the track lmao.

Yeah its looking like I might go with the LS swap or settle for 400hp. It probably be a better idea to learn to drift the RX7 at 400hp instead of jumping in at 700hp. Thanks for ur imput tho

Depending on what needs to be replaced and what mods are on the car, you will have more than $15K just getting to 400rwhp. Just the clutch to support 700rwhp is going to run $2500+, if it were easy and cheap to triple the power output, everyone would have 700rwhp. If the car is close to stock don't even bother with the 13B, just get a 20B.

It IS easy and cheap to triple the power output. My 4 port 13B made almost 3x the power of a stock four port 13B, and all I really needed to do was a good intake manifold, a decent flowing exhaust, and a bridge port.

You guys what play with turbos (you mean like trucks have??? How lame) are the ones who have all the problems.

(disclaimer: My winter/backup car has a turbo. It also has 8.5:1 compression, makes 300hp from 2.5l dead-stock, and is computer-wizard everything. It's not an OMG car, more of a "Jeeves, accelerate me thataway with all haste" car. For fun, natural aspiration is best aspiration)

https://cimg4.ibsrv.net/gimg/www.rx7...1c2b80908b.jpg

Glad I get to use this again. Always recycle.

lol

I almost responded when I read the initial post, then I was like F it. He'll probably ask how to adjust the valves next.

Unfortunately your budget is no where near the amount needed for a 700 rwhp build, have you even looked at the price of turbos, intercoolers, radiators, injectors, fuel rails, oil coolers, clutches, transmissions, computers etc etc? Even getting to 400 at that price would be a real challenge, even if you cheap out and do the labor yourself (and assuming you already have a running RX7 with a good engine).

Speaking of which, I have to ask - do you own an RX7 yet? Your budget will be fully used just buying one......

I strongly recommend you do a lot more research. Nice cars, with high power, built well are not cheap. If they were, don't you think a build as expensive as mine would have more than 375 rwhp?

I've got $20k in go-fast parts alone from a fully built semi peripheral port keg to CDI ignition and I'm just now closing in on 700hp. The first 400 is easy, the next 300 is not.

If you want 700hp out of $15k, you're going to need to buy a junk beater roller and then swap an iron block 5.3 in it and spray it with a stupid amount of nitrous. 700hp simply isn't happening on a 13b without serious fundage and ability. And at those power levels, you best have money to replace the expensive keg when it lets go and not mind doing so, because it ultimately will.

-Skeese

700HP on a 2 rotor is NOT realistic or smart. It's flat out STUPID unless you own a rotary build shop (and even they will tell you you're stupid) and want to show off or your drag racing with it or just want to throw away money. it would be useless on the street. It's like building a 2,000 HP v-8
but at least the v-8 will make more than 3 passes before it grenades

It is realistic, and can be smart if you are in the right position. I don't own a rotary shop and am not a drag racer, but can't say I haven't spent a ton of money. The point is not to run 700hp everywhere, but to have a 500hp street FD that you can crank the boost knob on and have 700+ on demand OR run a boost by gear setup so that you dont see the 700 boost until 3rd or 4th so you can hold traction and pull on the big end. I don't know about where you are from but 500hp, even in a FD, isn't enough to keep up with the big boy street cars here in TX.

That all being said, if you build the motor and supporting system to hold 700, then run 500 most all of the time, the engine will likely last alot longer than the guy who builds for 500 then beats on 500 constantly. The key point here is that it is perfectly realistic and doable, but you have to have money to spend and know exactly WTF you are doing, or else its a wash and a time bomb.

Your opinion on the matter doesn't make anyone else stupid for doing something else.

-Skeese

.

Very nice how you can't stand behind your post and have deleted it.

Having a big turbo big power streetcar is perfectly doable. If it isn't possible for you, it isn't the the fault of the platform but owner error. If you spec your motor and supporting hardware to efficiently work together and balance everything at a system level, then the performance level of the rotary greatly exceeds the common perception (things like a bit turbo spools slow...).

This is Aaron Copeland's 700+ hp streetcar that gets driven more than most people's daily driver. 43 lbs of boost by 4600 with a 10k rpm power band isn't exactly waiting around for something to spool. I'm expecting similar from my S476 SX-E and will prove it shortly. Like I said in my last post, one of the biggest factors here is knowing WTF you are doing.

https://cimg7.ibsrv.net/gimg/www.rx7...18ca8517de.jpg


-Skeese

I just don't feel like getting in a pissing match with you and your self righteous bullshit. ErnieT made almost 850 on a 13b years and years ago. You're not doing anything revolutionary or impressive. You're just driving a drag car on the street and it's obnoxious AF.

Self righteous? No I'm just right, and I know it. You're the one deleting your post responses...

Sure 850 was drag car only 15 years ago, back in the days when an E6K was the high end ECU that you tuned using a chisel and a hammer. Modern weed whacker carb tuning is more advanced. Again, back to what I said originally, if you know WTF you are doing the limits change. Don't be such a pawn.

Skeese

Can you please get your liberal head out of your ass and stop acting like a fool? You've been on this forum for 5000 posts of garbage and nitpicking with nothing to show but a stock FD and an attitude. Go out and drive your car in the mountains since you're so close to me and show the world you can put your money where your mouth is.

Aaron does it big. Seth does it big. These guys should be respected within the community for continuing to push the RELIABILITY factor of their builds. We live in a modern era full of great technology and you're comparing it to a drag racing (likely methanol) 850hp car. 700whp is doable on e85 with reliability for the street, but as Seth clearly showed you, it's best to do so in a progressive power output as to not always run the motor that hard. Makes perfect sense. It's why roots supercharged cars are so easy to drive... Progressive boost curve.

So let's help the young guy and continue showing him how $15k isn't adequate...

Save yourself the heartache and go LS swap your Rx7 (if you own one) for $15k.
Holley Dominator + LS3 E-Rod + T56 Magnum = $25k build though.
Building a proper turbo LS setup is going to be closer to $35k.

He was also blowing motors left and right, he just paid Ray to keep rebuilding them with a quickness. At least, that's what Ray told me when PFS was still in business and I was a customer.


Any swinging dick can make power if they pour enough money into a car. I'd have FAR more respect for a person that can make and sustain 450whp than a person who makes 650whp on a dyno, then blows their engine 2 months later.

I'm sure he was blowing motors. Back then, there wasn't any real adequate engine protection like what we have with modern ECUs today. Save structural mechanical failure, you can pretty well set up every failsafe needed to prevent detonation/pre-ignition related failures. Fuel pressure, wideband leanout, air intake temp, coolant temp, oil temp, oil pressure, voltage drop under load, overboost, etc...are all controlled factors. Running high hp with no engine protection is a recipe for disaster...if anything in the system goes wrong, I mean anything, then kaboom. There is NO longevity to this motor without engine protection.

The kicker here is that if you aren't a moron and you built and tuned the car properly then you can sustain 650, or more. Most of the people who hate on that idea either haven't made that kind of power before to actually know, or can't afford to.

Skeese

STUPID was a very poor choice of words. Perhaps very passionate about rotary engines would have been a better choice.

As to the advancements in the rotary. I'd say there small in comparison to what piston engines are doing today. Even the Mazda LMP car runs a 600 HP 4 banger(she runs all day and all night). Between the head designs, variable cam timing, fuels, ignition systems....even variable compression now..... a 4 banger pulls off the line like a v6 at a minimum.

who doesn't love 10k rpm's and flames out of the exhaust? who wouldn't want a 787B?

those #'s 15k, 25k, 35k w/turbo do not encompass an entire build IMO. not to make it like a new car anyway. IMO you could go out and buy one of several BRAND NEW street cars from the factory, with a warranty, making that power for the money you'd spend to try and make a rotary that would compare. I think those advancements mentioned have bridged the gap rotary engines had over their piston counterparts.

I can tell you from the standpoint of an owner of a 700rwhp street driven FD (683rwhp low boost on my Mustang dyno, you do the Dynojet math) that it is a handful to drive. My FD has been a 20B for nearly a decade, I have never blown it up (knock wood). There is none of the modern driving technology that is incorporated in the new Hellcat, Corvette etc, so basically every time I get behind the wheel the car tries to kill me. I have 35 years of driving experience and would never hand the keys over to some teenager, chances are they would not make it a mile down the road. Just one moment of distraction and it is all over.

We build and tune 400-500hp cars every week, it is safe to say that if you go into a project like this with a meager budget (read $15K) you are going to very unhappy with the car's performance and reliability.

Merry Christmas

I completely agree. There is a solid reason that no OEM currently has a rotary engine in production. I never said that building a 700+ rwhp turbo rotary street-car was smart, only that it is doable with money and some mechanical intuition. To me, pushing the limits of the platform are what make it fun and challenging. If it was really about the power and having it in a FD I would have put a supercharged LS3 in it a long long long time ago and been set.

When building a 700hp turbo rotary you have to design, plan, spec and tune it as a system level approaching it like OEMs do. At this power level, we are so far beyond the capabilities of the system that Mazda designed so you must account for EVERYTHING where as on a 450hp build you can bolt a hodge podge of parts together without much forethought and then go beat on it. At big power your margin for error is much smaller than at 450, which just means you need to know what you're doing.

Skeese

This is all very true. With my last setup that was somewhere just north of 600 wheel, I could blow 26x10.5 mickey thompson drag radials loose at 90+ mph on the freeway. Feeling the back end start skating sideways at those speeds is pretty scary no doubt. I get alot of people who want to go for a ride, but not alot who come back for a second time. It definitely isn't for everyone.

Skeese

You talk a big game, but at the end of the day you're an amateur with limited experience. You bought that motor (or maybe you're building a new one?) from socks, who was using it for....DRAG RACING. A 700hp 13b is half grenade and half turbo lag. The people who make that much power (or more) rebuild often. Technology hasn't really changed the limits of the stock block and materials. It doesn't matter how deep you bury your head in the sand or how hard you beat your head against the wall. You're up against metallurgy and physics, not tuning and electronics.

But, please bring back some track and autoX videos of your totally streetable car with a hood dump exhaust. And, let us know how many pulls/miles you get between tear-downs. Seriously, you're building it for drags and roll racing, which is all it will be good for. And, engine longevity, reliability, and driveability won't be in the same zip code as lesser powered engines.


LOL. U mad I upset your BFF? This is you right now:

https://cimg5.ibsrv.net/gimg/www.rx7...cf1fc12d35.jpg


Roots superchargers are the least-progressive form of forced induction. See picture above. The reason a huge turbo doesn't make more boost/power sooner is purely lag. And I'm pretty sure ErnieT was running C16.

True as the financials are, the real takeaway is that a 700hp 13b is not particularly desirable or achievable for anyone who finds this line of questioning informative.

Oh look, a professional with a running car and a shit ton of experience. Merry Christmas indeed. Seems like the extra displacement of the 20b makes those numbers much more realistic and reliable. And, 400-500hp is a much more reasonable goal for 99.9% of single turbo 13b builds.

Best of luck with everyone's respective automobiles and builds, whatever the power level or intention.

Here's a thread that's less worthless, in case anyone stumbles in here by accident: https://www.rx7club.com/alternative-...-921995/page4/

My car made maybe 2.5x what a stock 13B made.

What is interesting is that an FDs engine is more or less the same as a 100hp Cosmo 10A engine. There are some minor detail differences, but it's the same engine. Arguably, the FD engine is worse for high power output, since Mazda has demonstrably compromised the cooling system in the FD engine in order to get the spark plugs in a better position for emissions reasons.

Really, a 700WHP engine is 8-9x the stock output. Mazda burned the candle at three ends when they made the FD engine to begin with. That is why they had such a hilariously short lifespan.

Tuibos are for trucks, mkay?

Are you high or something?

Why would you ask that?

Peejay is right, the 13B-REW is essentially the same technology as a 1960s 10A.
Refined in a couple areas and further compromised in others.

The 13B-REW is essentially to the 10A what a 1980 Pontiac 301 turbo V8 is to a 1955 "small block" V8.

13B-REW Refinements over Cosmo Sport 10A
Larger thrust bearing
Thinner 2mm steel apex seals VS 6mm sintered Carbon/Aluminum (note NSU was already selling Carbide tipped apex seals and Mercedes tested with ceramics in the '60s)
Rotors with more roll pins holding rotor gears
Chrome over sheetmetal insert lined rotor housings instead of Chrome on Aluminum (more durable)
Higher oil pressure
Reduced friction (missing a set of side seals and rotor oil seal)
Improved accessories (ignition, fuel injection)
Removed oil pump chain tensioner
Turbos for POWAAAA (280hp instead of 120hp)

13B-REW Compromises compared to Cosmo Sport 10A
Rotor width added to bump displacement twice (12A, 13B) which compromised efficiency/design from original parameters (cost saving measure instead of "stroking" for displacement).
Cast Iron instead of Steel flame sprayed Aluminum side housings (cost saving measure)
Heavier rotors (because wider)
Chrome over sheet metal insert rotor housings (worse cooling)
Missing 2nd set of side seals (fine until rotor oil seals start to leak)
Missing 3rd set of oil control rings (fine until they start to leak)
Not hand ported from factory
Later opening intake ports (see above)
Smaller coolant passages in rotor housing (worse cooling, but better cold start emissions)
Smaller capacity oil filter (save the planet)
Much heavier (407Lbs versus 225Lbs)

Mazda took the wrong path for their production rotaries.
They should have stuck to the 10A and started adding rotors instead of adding turbos and/or wider rotors.
They started down the wrong path in racing (turbo bridgeport 2 rotors) and corrected (3 rotor then 4 rotor NA)

The weight shows all.
A 4 rotor 10A based engine would have weighed the same, made the same power, similar fuel economy, similar cost (New Hitachi twins cost same as brand new 13B-REW...) and would have much more reliable...

So you're telling me an RPM dependent boost curve isn't progressive... ROFL.

Here's the rundown for you since you need to be spoon fed still:

• A supercharged car makes less power at idle and lower RPMs than an NA variant due to parasitic losses
• As RPMs raise, so does the actual boost figure generated by the blower = a progressive boost curve
• Above cruising loads, you'll generate boost proportional to your RPM in which it's now surpassing the parasitic losses vs. just having an NA engine
• With a "12psi pulley" for instance, you might generate 5psi at 3000RPM, 8psi at 5000RPM, and 12psi at 7000RPM. Again, progressive boost curve.
• A progressive boost curve aids towards durability due to the duration at which you're loading the engine with higher and higher forces
• Smart engine tuners taper in boost on ANY application because making a fuckload of torque at low RPMs is what destroys engines
• So yes, you can make your 700whp, but I sure as fuck wouldn't run 30+psi under 3500RPM on a rotary engine. At 5000+RPM, sure! Build a progressive boost curve...

Your other shit isn't helpful, funny, or even worth reading, so I'll leave it at that. Thanks for proving my point.

Every day is a classroom...

oh i dont know, if you compare Mr Rink's 1971 Rx2 and and my old FD, the FD engine makes 3x the power, and gets better gas mileage. engine life is about the same.

you can have fast, cheap or reliable, pick two... or pick one! or pick none! loud, slow and broken is easy

Roots
Style
Superchargers
Are
The
Least
Progressive
Form
Of
Forced
Induction

I cannot understand you when you speak directly out of your asshole. Why should I take anything you say seriously when you're so confidently incorrect?

https://cimg4.ibsrv.net/gimg/www.rx7...fb11177152.gif

The mod staff has received complaints on this thread. We have a could options here. We can stay on point and drop the name calling and insults and get back to the focus of the thread or I can close the thread and we can all be done with this discussion. I'll let you guys choose. If the mod staff receives another complaint I will close this thread. If the original poster would like this thread closed he can chime in and I'll close it.

You keep using the word "blower" but keep describing the characteristics of a centrifugal supercharger. They are as different as wings and spoilers.

Blowers generally make the same boost at all RPM. That is to say, none at all. Boost with a blower is created by backpressure between the blower and the engine, since the blower is not an air compressor like a centrifugal supercharger (belt or exhaust turbine driven) is. Boost with a blower therefore is a complex relationship between the engine's VE (higher VE, less boost) and the blower's VE at that given blower speed and manifold pressure (more pressure, lower VE). The end result is that boost tapers off towards redline as the blower gets less volumetrically efficient at higher RPM.

What was this about school, now?

Yes, I bought this motor from Sean/Socks who did on occasion take the car to the 1/8th mile. When he did so, he drove it there on street tires, and his slicks in the hatch. He'd swap tires at the track, drag race, then swap tires put the slicks back in the hatch and then drive the car 45 minutes home. Drove it to work, drag strip, cars and coffee, or wherever...because its a STREET CAR.

Car doesn't run a full time hood dump. I have a full 4" that I welded myself with two mufflers. The hood dump is something I can just slap on whenever I want to offend people like you. I built it, drive it, pay for it, and tune it myself so your opinion on what it is or isn't is irrelevant.

So honestly man, you can fuck off. :asshole:

Skeese

Pure gold.

https://cimg3.ibsrv.net/gimg/www.rx7...f305db7621.png

Well, let me show you another turbo vs. ROOTS compressor boost curve:


https://cimg0.ibsrv.net/gimg/www.rx7...b8ca80217c.png
There's a difference between a ROOTS and a SCREW style supercharger. You're entirely correct that a CENTRIFUGAL supercharger also has a PROGRESSIVE BOOST CURVE, which is the entire reasoning behind my portion of this discussion.
We're not talking about supercharging, we're talking about building in a progressive boost curve to make your engine LAST LONGER ON THE STREET AT HIGHER POWER LEVELS.
You understand 'progressive', so understand that you can make 700whp safely on a motor if it's above a certain RPM threshold and you sure as shit aren't running some garbage ECU.

It's not like you'll ever get there, Narfle. You won't even modify your car, so what experience do you have?


Oh, this thread is absolutely over with, just close it. The OP asked a dumb question pointing to CHEAP + FAST, and our answers are all either spend more money to make it reliable or your goals are unreasonable for the usage of the vehicle.

You gotta stop making blind assertions. It belies your youth and maturity. And, it damages your credibility. You haven't been right about me yet.

When you two are busy being enthusiasts and sharing your experience, you're great. When you're pretending to be experts and disrespecting the rotary community and establishment that made you possible, you're both awful and unwelcome. And, trust me when I say I speak for the people who matter. The racers and vendors that are actually advancing the technology and community blow you two out of the water. It's not close. It's not even a valid comparison.

I'm just a bored-assed engineer on his 3rd FD with 15+ years of (mostly vicarious) experience, who's been obsessing over all things rotary and reading every page of this and other rotary communities. Think of me as Quality Assurance. I've seen enough bullshit to pick it off the assembly line.

Your Resident Asshole in Chief,
Narfle

P.S. I've grown to appreciate the stock car, Mazda engineering, and not having to evade CARB. Molesting my previously-one-owner car would be borderline sac-religious. It would be like looking at the Mona Lisa and thinking "Da Vinci, what a hack!" If I wasn't busy spending what is apparently a reasonable 700hp build budget on my child's education every year, maybe I'd buy a beater FD to screw around with. One day you'll understand.

This is the olive branch. If you can't take it, I'm coming back with the hammer.