dirtbikedud88

Building a highly top secret project car and looking to use a rotary engine. (More in my intro thread). The car is in need of a larger horsepower engine in small package, so we turned to a rotary engine and trans but don't know much about them. Have many questions to be answered. Which generation do you think is best? Have heard that some generations run two turbos and some with only one, more detail on this subject would be great. What horsepower can these engines run up to? What needs to be done as far as turbos, intercoolers, internals, and trans upgrades for the car to be reliable with lots of horsepower? How hard are these cars to tune? What hp are the transmissions rated for? etc. etc. As much info as possible will be greatly appreciated.

RobertC

iTrader: (1)

What do you need the car to do? Are you trying to turn the car into a track car, drag car, off road, sand rail? There are so many different routes you can take with any motor beyond just rotaries. You will have to divuldge something for people to be able to give you input of any sort.

What sort of budget are you working with? Are you and your father going to be doing all the work on the motor when it needs it or are you going to be having a shop doing that part for you? What is a "larger horsepower" motor in your opinion as far as a number goal?

misterstyx69

iTrader: (142)

hmm..top secret but asks public what is good?...(blueberry pie..and a hopped up TII FC!)

I got 357Hp at the wheels out of a stock TII keg..

Sgtblue

iTrader: (16)

You're (only) 20 years old but a mechanical engineer. You have this idea for a project and it's so cool that it's "top secret" because you're afraid someone else might steal it? And want to build a monster rotary engine for it. But since you know nothing about them, and despite your assumed academic experience, you come to a forum to learn about them?
Well, without the cat, a rotary exhaust can smell funny.

The Wankel Rotary Engine: A History : John B. Hege : 9780786429059





Styx, did you leave your car idling again?

dirtbikedud88

I am going to school to be an engineer. Why do you need to know all of the details about the car to explain which rotary engine is best and which rx7 is best haha? The car will be a street car that is driven as a hobby car. We probably will not be doing the work unless it is manageable. We have never done work on rotaries or have owned a rotary. 300 hp is probably good hp since the car will be so light. Can they push 500 hp? As far as turbos and intercooler kits go what do they run and what hp can the kits run for the price? what difficulties do people run into when tuning? Since we will be using the wiring how complicated are the harnesses and has anyone messed with the wiring?

misterstyx69

iTrader: (142)

I think you should start in the BUILD section and take a look at what others have or are creating.
The wiring?..Crappy..if you use the stock wiring you are limited to either the Stock ECU which won't support the Higher HP numbers you want or an Aftermarket that uses the wiring.
Most Aftermarket ECU's will have a harness that you need to use to hook up the necessary components to make the engine run,eliminating half of the crap that the stock engine comes with(emissions junk).
You can't tune a stock ECU(unless you have an FC..then get an RTEK,.that is a chipped stock ECU).
Properly fitting Intercooler kits are few and far between.A lot of guys just opt to make up their own version.Some of the "kits" are down right pricey.(Greddy)
Turbo Kits..again..it depends on what CAR you have and what HP you want to run.
(check out Turblown on here).

Now If you are handy,most of this stuff will be easy on your wallet.
If not then expect your bank account to start getting smaller.It adds up real quick..but at the end of your sorrow you will get a car that will pass everything but a gas station!

Aaron Cake

iTrader: (1)

All you need is 300HP?

Any FC or FD engine.

The FD engine is the most advanced in all RX-7s and has incremental improvements over the FC. Thicker rear iron around a weak point, more bearing clearance, better rotor housing chrome, lighter rotors (but same as S5 FC), trigger wheel vs. CAS, more modern high impedance (though annoying side feed) injectors, etc. etc.

You likely won't use the twin turbo system due to the fact it is a clustershag. Instead a more modern single turbo (ie. GT3076R, 1.06 divided T3).

You won't use the FD ECU. It's a dead end. A full standalone is the way to go.

But without knowing more of what you are trying to do, that's about it.

And yes, 500HP is possible. But is orders of magnitude more involved and expensive than just 300HP. Also 500HP is well beyond what is usable on the street.

dirtbikedud88

It seems that the FD is better than the FC. As far as the FD goes, is the 2002 model more advanced than the 1993 as far as engine and ECU or are they pretty similar? These cars push 350 stock with no mods or tuning at all? To put 400 to 500 hp to the wheels would it be more expensive to upgrade an FC or an FD and will it be reliable? Is there a wide range of ECUs to choose from, and what are the popular companies selling them? Are you guys buying the intercooler tubes and intercoolers on a site and piecing them together or are you fabing them up yourself? And switching the twin turbo to single turbo setup is the turbo mounted in the same place or did you have to build a mount for it or do they sell one?

diabolical1

iTrader: (3)

Yes, somewhat. Aaron pretty much stated as much. The S5 FC turbo engine had improvements over the S4 engines, but naturally evolved further into the S6+ turbo engines. Coatings, ports, housings, e-shaft, bearing, intake, ignition, etc. were all little improvements, but for 300 HP, it simply doesn't matter. any turbo block will do just fine or blow up just fine in the face of blatant, gross assembly and/or tuning mistakes.

your location says Vegas and S6 was the last version here. so unless you plan to go out of your way to get S7 or S8 engines, what difference does it make? i honestly don't know what changes were made to the engine itself by the time 2002 came around, but i feel confident saying that it wouldn't be anything significant - and by significant, i mean something that would make the engine itself take say another 100 HP, or even 50 over the S6. they have been proven to hold well over 500, unopened. knowing what you're doing goes a long way, much further than choosing which block to use.

it's not really fair to say FC vs. FD because as said before, the FC spanned two turbo engines, and one of them was a marked improvement over the other. the S5 should theoretically hold up to power levels similar to the S6 engines. the accepted "physical" limits of the S4 engines seem to be on the left of 400.

you stated you were going to school to be an engineer, so you should know the concepts of precision by now. you stated that just before asking why we need details of the car in order to answer you questions. most, if not all, of the questions you asked in this section of you post are a shining example of why it matters what kind of car. and by the way, you still haven't answered the question.

EMS will come down to budget, the features you NEED to have, who is tuning the thing and yes, to a lesser extent, which car you're putting it in.

pre-cut and bent intercooler kits are based on the car. if you have an application that is not supported by a kit, then you'll have to source the parts and have them cut and bent to suit. CXRacing comes to mind as a source for parts, but there are others out there.

turbo mounting depends on the car.

RobertC

iTrader: (1)

Taking what diabolical said and basically summarizing, you are looking at a custom install on all auxiliary engine parts (ie Intercooler piping, Intercooler, turbo, manifolds, exhaust, etc)

300 is a realistic number to hit and stay reliable. 400-500 you will be making it harder to get there, and it will not be near as reliable.

You didn't answer what you want the car to do. Is it going to be a street sleeper for racing? Autocross? Track? Show car? If it's going to be a drag car what kind of cars do you want it to beat? You can make 500+ hp but if you only have a powerband of 500 rpm you won't be able to use it on anything but a dyno.

Sgtblue

iTrader: (16)

The later series FDs had a little more efficient turbos, slightly better flowing components and a 16 bit ECU vs. the earlier 8 bit. Later series also improved on the sequential management system. Only the S6 was ever imported into North America 93-95 and it (only) made 255 hp at the FW...maybe 215 at the wheels. All trivia if you're going single, increasing boost and adding a standalone ECU...which you WILL need to do to meet those power goals mentioned.
If you're just talking engines, for your purposes, as explained previously, no real difference.
For 400 to 500 whp it will be expensive. Porting, cooling, fuel delivery, engine management, tuning, drive-train strengthening, bracing and on...and NO, it won't be reliable IMO. And the rest of your questions about switching turbos and intercooler tubes suggest you don't have any real experience and should learn to walk before you run if you plan on doing the work yourself.

Evil Aviator

The 16X engine with direct injection and laser ignition.

Have heard that turbosuperchargers can be attached to almost all 4-stroke internal combustion engines, and in any configuration that is deemed appropriate by the engineer designing the system for a particular application.

Over 800bhp from a 13B engine.

Once you take a few engineering classes in college you will realize that it is impossible to answer this question when the application is "secret". Additionally, the terms "reliable" and "lots of horsepower" are what we call "subjective". Therefore, my answer to your question is that what needs to be done is secret and may or may not involve lots of things.

Like many things that are typically performed by a professional, it is really hard if you don't know what you are doing. Naturally-aspirated engines are typically easier to tune than supercharged engines, and that applies to both rotary engines and piston engines.

Drivetrain components are rated by torque rather than by horsepower, and the application of that torque is also a factor. If you want ballpark hp figures for street cars with street tires, then a non-turbo RX-7 drivetrain is typically good for a 200-230bhp engine, while a turbo drivetrain is usually good for a 300-500bhp engine (the tires will usually spin before the transmission or axles break... usually, lol).

dirtbikedud88

Everyone is insisting that they know what car is being built but I don't really know how much that will help but I will say. The car is a 1956 Porsche speedster kit car. The kits are usually run on a modified Volkswagen chassis but we did not want to run the Volkswagen chassis, instead the car is sitting on a custom tube chassis with a corvette rear end and the engine will be up front.

Many are stating S5, S6, S7, and S8. What years do these correspond to? I have done a very brief search on craigslist here in Las Vegas and there isnt a huge selection here. Is it like that everywhere or is it just vegas? If not does anyone know of any cities in Arizona, California, or any states close by that these cars are popular? Or does anyone know of a place that we could buy a wrecked or salvaged car since we wont be using the body or chassis? There are two cars here in Las Vegas that are a pretty decent price one is a 90' GTU and a '91 fc vert na-t, any thoughts on these cars?

Like I said before, the car will be a hobby/show car that is driven for the enjoyment. It will not be a track car and it wont be a daily driver. The car will maybe only be ran on the drag strip once to see what it can do. Not looking to beat any specific type of car. At 300 hp what can the rx7's compete with due to the light weight? Stock or unstock v6 mustangs? v8 mustangs? GTOs? Evos/STIs?

I also know that many of the tuner cars run ethanol for more horsepower. Is it the same with the rotaries or are they not compatible with the ethanol?

Everyone is saying "deep pockets", "declining bank accounts", and "expensive" but what constitutes as expensive to push the 400-500 hp? $5,000? $10,000? And was that a shop doing the work or did you do the work?

RobertC

iTrader: (1)

When we say it can get expensive if someone is doing the work. The motor alone to have some one do that work can run you up to 6-8k just for the motor. Up to 10k for the labor to get the stuff done (including the motor and everything). Because of your specific application it could go up from there. And thats not taking into account pricing for turbos, intercoolers and fab, exhaust fab, etc. As you know, with anything that is going to be a one off, you can't just go and get the parts used or anything. Everything is going to be custom made and you will see it will cost a little more.

If you are looking for just a motor, you can contact most any rotary engine builder and they can put something together for you to meet your needs.

Rotary Performance, Kilo Racing, Banzai just to name a few of the shops that I have done business with and would suggest to look into for their service.

As far as what a 300hp rotary will beat. Quite a bit. Most everything you mentioned.

Also take into account when you are up front with the people you are asking for advice, I find that you will get a better response with more input based on your application. Sounds like it will be fun and good luck with the build.

You had me laughing by the way Evil Aviator.

diabolical1

iTrader: (3)

knowing your secret plan wasn't really the point of asking what kind of car it is. i'm sure most of us suspected that it wasn't an Rx-7 just based on the cryptic nature of your post about a "top secret" project. however, you did remain ambiguous and there were some questions that made me (speaking only for myself) think it may have been an Rx-7 (e.g.: intercooler kits) after all. anyway, enough on that ... i will move on.

look, you have a crap-ton of custom work ahead of you. as far a price tag goes, your guess is as good as anyone else's as to where this ends. i will try to let this be the last time i make any mention of whether or not i think you're serious about all this, but i am taking the time to try and help you in earnest, so i think i am entitled. fair enough?

i will take the time to run down a few numbers, but keep in mind that other people may have different numbers to suggest for the same items.

to build a solid engine that will run 300, as was said quite a few times, any turbo block will do.

1. price of acquisition can be a anywhere between $500 and around $1,600. it will depend on a few things, but source and condition are the biggest. my advice would be to try your best to get something on the low end of that spectrum because even the higher end engine might likely need a rebuild.

1a. there is also the option of finding a fresh engine that someone is getting rid of, but unless you can verify the quality of the build and/or maybe hash out some kind of protection for your end, it could be a sketchy proposition.

1b. if you do have any intentions of pursuing 400 or 500 HP, then you will be best served starting with at least a S5 engine. my experiences looking for them shows you're more likely to come across an S6 engine, but you will likely PAY FOR IT. prices are kind of funky right now.

2. it would be wise to figure that you'll need a rebuild after getting the engine. i would highly suggest you budget at least $3,000 for that. can you get one build for less? of course you can. however, i chose $3,000 because it's pretty middle of the road. rather it's the lower end for something that will be thorough and have new parts as opposed to spec'd used parts. keep in mind a set of NEW rotor housings alone is about $1,500! perspective yet? now you can see how someone might charge $5,000 for a quality rebuild.

2a. you do not NEED any porting done for what you want, so don't get talked into, unless you just want it ported. however, as with everything else in life, porting will cost more. usually $300 to $600 for a streetable setup.

3. Turbo - of course there are used deals to be had, but i have no clue on prices for used turbos that will get you 500 from a 13B. i would say count on spending at least $1,400 for the turbo alone. it could be more. it could be less.

3a. obviously, you are going to need all the things that come with a turbo setup: manifold, intercooler, piping, wastegate, blow-off, etc., etc. i have no figure for you, but good manifolds are not cheap. you can find affordable intercooler cores, tanks and piping, but everything does add up, so ....

3b. you will have to do it this way because kits will do you no good. they do not exist for your application.

4. Fuel. Rotaries are thirsty. they require more fuel than reciprocating engines. you're looking at BIG money. Period! things like injectors and rails you can probably get in kit form. the FD guys are likely to be able to steer you in the right direction for those. however, lines and tank/cell will all be custom work and likely to be big money.

5. EMS - this is truly a can of worms that can cost just about $1,000 or go up to the price of a Camaro. literally! again, your criteria for choosing one should revolve around who is tuning it and what features you require.

6. i will not touch transmission/clutch or exhaust because i have no idea how the car is going to be built - front mount and longitudinal, or rear/mid mount and custom transaxle. what i will say is rotaries require massive provisions for cooling. you will need oil coolers and a radiator. while old air-cooled Porsches did require fairly comparable oil cooling, they obviously did not need radiators. so you will have to work all of that out. given the size of the car, you're probably looking a high volume system to compensate for the lack of space for a huge radiator core. the mounting will be almost as essential as the ducting and airflow.

S4 - 1987-88
S5 - 1989-91
S6 - 1993-96

S7 and S8 - i have no idea. i'm sure someone here (maybe SgtBlue) will know, but you can always check on one of the Aussie forums or Google it.

i'm tired of typing now, so whatever parts of your post i missed, i apologize. i can either get to it later or someone else will pick it up. just keep in mind, i'm only talking about things associated with the engine itself and your stated goals.

dirtbikedud88

Have you bought a full engine from any of these companies or did you just order parts from them?

These replies are all very helpful and will definitely give us an advantage on our build. So for a solid build it appears that we will be looking at 10,000 and upwards probably to 15,000.

We will also need gauges for the car. As far as stock gauges are they ran off of the EMS, ECU, or do they just run off of individual sensors that run directly to the gauges? As an old school car we would like to run factory style gauges.

Does the EMS require its own computer type system that must be monitored all the time (by the driver) or is it set up then it runs itself? I'm not really understanding the whole EMS fully.

Aaron Cake

iTrader: (1)

All gauges until the FD ran off their own sensors and independent of the ECU.

FD runs the speedometer via a transmission output that runs through the ECU but can be bypassed and run direct. Tach is driven by the ECU but any standalone that doesn't suck has a tach output.

As for the EMS, yes, it is initially tuned via a computer but once set up doesn't need to be changed unless the configuration of the car changes.

RobertC

iTrader: (1)

I have had a motor built by Rotary Performance. Great customer service and very good work. They were able to source me a core motor to use for the build as the motor I had had severe overporting (rx7store.net) on the intake and exhaust and cooked the oil control rings within 5000 miles (Gotta love the outer oil control ring being exposed because of the port work on the intake. ) and was no longer useable as a base to build from.

dirtbikedud88

Awesome. Thanks. And that is great maybe we will hit them up for an engine. Do you know where they are located?

Aaron Cake

iTrader: (1)

Let me google that for you

iBillz

Most reliable in my opinion is FC N/A

Aaron Cake

iTrader: (1)

The most reliable is the last generation of 12A. They run forever. But they also make no power and parts are very hard to find.

FC took a reliability hit due to stupid 3 piece seals. They are literally a timer on how long the engine will last. Because once the top piece wears past a certain point, it rolls out of the groove.

Sgtblue

iTrader: (16)

My S6 (manufactured in 92) had stock 3 pc seals too. Was that something inherited from the FC or were they a different design?

Aaron Cake

iTrader: (1)

I believe the FD got them to a point. Then Mazda switched back to 2 piece.

diabolical1

iTrader: (3)

SgtBlue~
for what it's worth, the information i read over the years is inline with what Aaron said. the FDs got 3-piece seals to certain point, and then switched to 2-piece. the REW that i have was an original (seems to be) 3-piece engine.