914 tranny?? Options

[skline]

PM sent, you better get going on that Essay if you plan to get it done tonight.

[Dairdevil9]

you guys think there worth getting or will the stock 901 CV's worl ok?

[skline]

How much power were you planning to run??? I would always start with the best but I cant afford to right now so I went with the stock axles, I figure if I break one, I will get the heavy duty ones (Bus axles) and then if they break, I will have the money by that time to get the HP ones.

[Dairdevil9]

thats prob. what ill do too. im gunna be running from 350-450HP (not sure yet, depends on what boost i run) so i'll prob just go with the stock axles and see what happens. have you looked into the costs of the bus axles? are they able to handle more power than the 911's?

[Brad Smith]

thats prob. what ill do too. im gunna be running from 350-450HP (not sure yet, depends on what boost i run) so i'll prob just go with the stock axles and see what happens. have you looked into the costs of the bus axles? are they able to handle more power than the 911's?

Ok, as a rotary guy I'm gonna jump in here. To get 350-400 hp you had BETTER be running an aftermarket ECU (haltech or equivilant) or you WILL blow that motor so fast you won't know what happened.

They are very sensitive to detonation, which commonly occurs when you run too lean. Keep the timing moderate and don't try to lean it below 12:1. (I know, that's a little rich, but it is good insurance.) And get a big intercooler.

Detonation breaks the apex seals, which in turn usually destroys the rotor housing and sometimes the rotor also.

I have a friend making 425 rwhp in his daily driven street car (87 RX-7 turbo) with a haltech and a 60-1 hi-fi (T04 based) turbo. The ports on it are not even that radical, it's how the package is put together. He's been driving it for about 3 years that way, and hasn't blown it up yet.

I also have another friend with ~650 rwhp in his high 9-second street legal (sort of) drag car. That's a 3rd gen. Now, HE blows motors- that's approaching the limit of a turbo rotary on gasoline. (Alchohol cars have been over 800 at the rear wheels, but of course that is strictly race-only.)

The common factor there is they ALL run aftermarket EMS. Don't try to hack up a stock ECU running bigger injectors and higher rail pressure- you can trick them only so far. For a second gen computer, 250 to 275 at the wheels is the limit, and then you are running on the ragged edge of reliability. A 3rd gen might let you get up to 350... beyond that you are just asking for a blown motor.

Brad

[tesserra]

If your engine is in the back, not mid engine, do not go through the hassle of converting a 914 trans. Go directly to the 915. These come from a rear engined car, can handle more torque, and have good ratios for a high rpm motor.
HP will not kill the trans, shock loads and high torque motors will.
If you go from low traction to high traction situations this is a shock load that will be very tough on a 914 trans, and fatal for the trans if it happens in 1st gear.

George

[Dairdevil9]

Ok, as a rotary guy I'm gonna jump in here.  To get 350-400 hp you had BETTER be running an aftermarket ECU (haltech or equivilant) or you WILL blow that motor so fast you won't know what happened.

yeah the motor i got/on its way is a 13B-RE (more intake ports better injectors) and it puts out more power stock than a stock 13B. and im planning on getting a aftermarket computer (wolf 2D) its about $1200 bucks but it will be money well spent. complete engine managment at the tip of my fingertips. everything on the motor is tunable with this thing. it has two programable maps (you can get more) which you can program however you want (ie. race mode/daily driving) and are available at the touch of a button instantly. pretty neat, you guys can check it out at www.wolfems.com. thats why i always give a range because its all depends on what i want to do with it but at the least its gunna have around 350 HP.

[soloracer]

The wolf 2d is only a fuel computer and not a combined fuel/ignition computer. Since you are running a turbocharged rotary engine you should go with a stand alone that controls both ignition and fuel. The 13b-re is basically the same as a regular old 13b. There might be some differences in cooling and strength of housings but for the most part it's the same as the engine in an RX7. Sorry but there are exactly the same number of ports and the injectors are no different. For the power you are talking about you will have to ditch the stock twins and go with a big single. Which makes it even more important to get a proven stand alone - and even more important that you find someone who knows how to tune it. No offense but it sounds like you really don't fully understand the rotary engine and I suggest you start with smaller goals. Otherwise you will end up with a car that will only frustrate you and break the bank before finally getting relegated to the corner of your garage.

As for my background I have owned an RX7 Turbo for about 6 years and have owned both the Wolf 3D and Haltech E6K engine management systems. The Haltech is a superior system in all regards and I highly recommend you look at getting one. I am currently putting a 20b three rotor in my 914 and running it with a Haltech E11. I am using a Porsche 915 transmission and am keeping the stock twins (for the time being) until I see how the car runs.

[Mueller]

Brad,

there is a guy in Brentwood (near the new Safeway off of Balfour i think) that specializes in RX7's and modifing them, he also sells and services Electromotive (and possibly other brands) of programmable fuel/ignition controllers..

found the company:

Shane Racing

[Dairdevil9]

I’m sorry I had an error in my last post. I put wolf 2d and I meant wolf 3d (version 4+) and it does WAY more than just engine fuel management. If you want to look into some of the features of the system and a comparison of the wolf and the Haltech check out this section of an rx-7 forum, http://www.rx7club.com/showthread.php?t=344621. (You might have to register though, but it’s really quick) soloracer was right that the 13B-RE doesn’t have more intake ports than a regular 13B-REW(rx-7 3rd gen) however it is different. It does come with larger intake ports than the regular 13B-REW which automatically gives it more power stock. I’m not sure about the cooling or stronger housings either. But I did hear that they came with more injectors but I want to put an emphasis on the word "hear" because I don’t know that for a fact, but I think that you’re right that they don't come with more injectors but I think they might come with larger ones. You were also correct in saying that I am not a huge rotary guy and I honestly know more than most but really not a lot at all. My brother however has. My brothers got a 93 RX-7 13b tt that is his entire life, and he knows them in and out, and that is why I have always leaned towards the rotary (full time mechanic). My brother has built 5 motors from the ground up, a few for his car and a few for friends, so he knows how to work on em. he has been cranking on rotary’s over the last 8 years so I trust he will steer me the right direction so I don’t end up hating my decision to go rotary. And Mike, that guy that you’re talking about in Brentwood is Ray Lochead and he owns sr motor sports. Him and my brother are buddies (thanks for the tip though). Soloracer, you should give him a call he has built 3 rotors for his drag car that pout out over 1000 HP! and as far as turbo's go you don’t need ditch the stock twins and go with a big single to achieve the amount of power that i'm talking about its very possible of getting to those numbers (reliably) with the stock twins. However we are now probably just coming down to matters of opinion and preference. Thanks for the advice on the computers. I will prob. still go with the wolf3D version 4Plus. Do some research on this computer and get back to me with some plus/minuses of things the haltech does that the wolf doesn’t or cant because I haven’t bought one yet and if it really is better... tell me why and ill buy it.

[Dairdevil9]

hey does anyone know if the 901 shift rods are the same as the 914's? also does anyone know if/where they sell nice shifters for the 911 901 transmissions?

[Mueller]

for the shifter:

RennShift, made and sold by a fellow club member

for you application, a 'bug shifter might even work or just about any type of shifter with a few mods

the shift rods are going to be different between pretty much each different transmisson (901, 914, 915 etc....)

what is everyone else using on the 'rails??

I couldn't imagine anything being a true bolt-on unless you are using a frame kit from a manufacture that already has everything laid out for what to use.

WEVO makes some really awesome shifters as well for Porsche cars

[Dairdevil9]

hey mike do you have any 911 parts? shift rod, axles, shifter etc.?

[Dairdevil9]

and does anyone know the difference between the 915 and the 901?

[Mueller]

nope, no extra 911 parts (mostly cause I have not taken my 911 apart, LOL)....915 is a more modern, heavy duty transmission, able to take more hp and abuse...they weigh more as well, something like 125 pounds instead of 75 (not exact wieghts, just wild guess)...the 915 also tends cost more as well the accesories (shifters and such)

one thing you need to figure out is the gearing and depending on how tall of a tire you plan on running, whether or not any of these transmissions would be optimal...changing gear ratios or ring and pinions is not a cheap or easy job.

[Dairdevil9]

im gunna have some large tires in the rear. not exactly sure how tall yet but would larger tires effect the ratios in a negative way?

[Mueller]

the diameter of the tires makes a huge difference....

you want your powerband to be usable, too tall of a tire and too high of a gear and you might not ever be able to get the engine in the higher rpm range you want or need to get up the hills.....

[Dairdevil9]

do you know of a site or have the gear ratios for the 901?

[Mueller]

Gear Ratios for 901, 911, 914 & 915 Transmissions

[Dairdevil9]

awesome. thanks mike