Ask your "dumb" questions about RX7's here

I know there are many many thread on here that have questions that are refered to as being dumb, or stuipd, pointles ect ect.

But if you are thinking about it then im sure there is also somone else out there who has thought the same thing. So id like to head about all the questions people are affraid to ask. It can be about anything at all. Dont be affraid to ask. And please dont flame anyone because you think there question is stupid or whatever.

If you dont have anything important to contribute then dont contribute anything.

Alright, I'll start. Does anyone here know of a good rotary engine mechanic in the Los Angeles area?

I have a 1986 base that needs a water pump and perhaps some additional grounding. Thanks in advance for any advice.
-Drew

you can do that stuff pretty easily yourself

ok n herres mine, why is it on all the sites i go to that have rx7 shit ALWAYS ALWAYS have a ground wire kit.. for the 86+ rx7's is the grounding kits in the from the fact. shitty or what?

Well 20 year old grounding straps that are exposed to the emelents and removal and instalation over that time tend to go to crap :P I run my own grounding cables on my car. There is no need to spend $200 for a grounding kit that costs no more than $50 to custom make to your application.

What dose it take to swap a 1987 turbo motor into a 1987 non turbo car?

I ahve a 85 RX7 GSLSE is consuming fuel more than normal . When I check the engine oil level I notice fuel is getting mixed with the oil no problems with the car it starts and run good in any weather??
I am in MD any shop close that can help

What dose it take to swap a 1987 turbo motor into a 1987 non turbo car?

TII engine
TII wiring harness
TII ECU
TII hood (if running stock top mount)
TII flywheel
TII clutch
TII tranny
TII driveshaft and diff

Othere odds and ends but thats the just of it.

I ahve a 85 RX7 GSLSE is consuming fuel more than normal . When I check the engine oil level I notice fuel is getting mixed with the oil no problems with the car it starts and run good in any weather??
I am in MD any shop close that can help


Have this looked at ASAP. Fuel in the oil means that the rotors housings are getting washed out, meaning very little proper lubrication and possily a dead engine if not adressed soon. My guess is a stuck injector as it is an SE and has a 13B in it.

TII engine
TII wiring harness
TII ECU
TII hood (if running stock top mount)
TII flywheel
TII clutch
TII tranny
TII driveshaft and diff

Othere odds and ends but thats the just of it.

dont forget the starter and knock sensor.

Why do rotaries backfire so much?

All a backfire is unburnt fuel igniting in the exhaust.
The reason its so common on RX7's is because they run rich and hot. Those combined will give you a backfire and possibly the fireball everyone loves :P

How many pistons does an rx7 have? ;)

ok on a serious note, anyone have a good link to a write up on how to remove the vac rack from an NA engine? I've seen brando's thread on teamfc3s but I don't know how it applies to the NA motor as his is turboed. I've been at a stand still for a couple months on my engine assembly because of this. That and I'm just lazy :D

i thought you just take it off and cap the holes (wrong term i know)

I think there's some fuel line rerouting as well. I dunno, it might be simpler than I'm making it. There's some electrical stuff on the rack too though I believe. Hell I rebuilt the motor with help from the rebuild video but I need some good pics and instructions. The thread I read no longer had any pics so it was hard for me to visualize what I needed to do.

i hate to just throw this in here but this should be stickied at the top for all the people that are new, and have questions about there motors/ RX's...mods?

Why is it Mazda Techs won't even perform a tune up on an 86'? I mean seriously they sold the car. So why not fix it?

On another note.

What are some good mods but aren't too expensive? As I do have a fair bit of money to throw around, but if I want to do both cars up then I'm at the point where I could be strapped for cash.

Does Macco do good body work?

If I can't do my body work in metal, how long will a bondo/fiberglass job last?

Yeah, other then that, just read any threads I start, as most of them are dumb questions to the Rotary Seniors.

Why is it Mazda Techs won't even perform a tune up on an 86'? I mean seriously they sold the car. So why not fix it?

On another note.

What are some good mods but aren't too expensive? As I do have a fair bit of money to throw around, but if I want to do both cars up then I'm at the point where I could be strapped for cash.

Does Macco do good body work?

If I can't do my body work in metal, how long will a bondo/fiberglass job last?

Yeah, other then that, just read any threads I start, as most of them are dumb questions to the Rotary Seniors.

Mazda techs have no clue how to fix/repair rotaries. You need to find a local rotary shop.
Mods for NA's that arent expensive motor wise are few and far between. There is alot out there for almost every othere aspect of the car tho. TII's have alot more potential in the power/engine department than a NA and also offer the same chassie and such mods.

Macco sucks the big one, even bigger than a blue wales one.
Bondo fiberglass is horrable for body work stuff. It should only be used to fill MINUTE areas and even then i hate the stuff. It will not last that long. A few years if professionaly done.

Okay well, as I don't have a Mig Welder, I have to find someone who does that I can borrow, as if I am going to do this I would like to do it right. (With some minor interior parts and pieces like the seats, they will do for now, but in the future will be replaced with some fancy Name brand, unless you can think of something else?)

I realize that the TII's have more potential but as I would like to drive the car in the winter I would like it to have some road sticking abilities, hence why I want to do both vehichles.

Local Rotary shop? that's in Calgary I guess.

How does the Cold start Assist fluid work?

is there a rev limit for rotaries ? i ask because with an internal combustion engine (you know, the one with them pistons) you have the risk of breaking the con-rods under the forces of the engine and the risk of the valves hitting the piston, so in theory you could run a rotary at a huge amount of revs, so what is the limit, and what could you increase it to ?

Well as you have no conecting Rods, valves, valve springs, or anything like that, a Rotary (from my understanding) will keep going and going and going until you can't feed it enough air/fuel. At that point the motors topped out at like... 50k RMP. (not really but you know what I mean)

as far as i know...which i guess isnt much...its usually around 10-12k rpm...that with a lightened rotor assembly...weighs like 1 1/2 less than the stock...its balanced ect...which 10-12k is alot more than the stock 8-9k...so i think that might answer your question...

really ? i thought it would be more, since F1 engines rev up to 19,000rpm, but thats using compressed air valve springs, not conventional "wound" ones.

I don't know about that, as my Dads old RX-4 Turbo would go up to 20k....

I don't know about that, as my Dads old RX-4 Turbo would go up to 20k....

that's more like it !

what as the boost pressure like at that point ? must'a needed some serious boost control. did it have an internal or extrenal wastegate ?

I'm not too sure, as I am still new to this whole RX scene, but, at 20k RPM I think he was only getting 10-14psi on the boost gauge, don't quote me on that, as when you sit in the passenger seat things are not always what they seem to be.

yea, but hitting 20k is sweet.

Yeah, it sure is, Specialy when you grab fifth doing about 18k, totally bent... I loved that car... I miss that car....

wow, my mate hit 12k in an S2000 supercharged, i was in the passenger seat. top down, roll cage. about 400bhp.

slamming into third after a hard launch in that thing scared the hell outa me, but 18k ? wow, i gotta try that some time.

did you drink the car, or were you just a passenger in it ?

only ever the passenger, my old man didn't trust me behind the wheel of it, as he finally got rid of it when I was 15 So he wouldn't let me drive it.

That thing was just insane.....

Such a nice car though.

did you drink the car ?

where the hell did i come up with that ?

We are not too sure, but I knew what you meant.

is there a rev limit for rotaries ? i ask because with an internal combustion engine (you know, the one with them pistons) you have the risk of breaking the con-rods under the forces of the engine and the risk of the valves hitting the piston, so in theory you could run a rotary at a huge amount of revs, so what is the limit, and what could you increase it to ?There are limits. And they're well below the 12K, 18K, and 20K mentioned earlier.

First, a bridgeport or peripheral port is necessary to make any decent power at such a high redline. You'll need carbon or ceramic seals, since the stock seals won't hold up at higher revs, and will chatter. Custom hardened stationary gears are required, and you'll need a dry sump pump to keep everything VERY well lubricated (the stock oil pump will foam up the oil very quickly at higher revs). Lightened rotors are necessary, which have been clearanced, and you will want the whole thing balanced too. A center bearing is a must as well (you'll need to install a roller bearing in the centerplate and machine the shaft to suit). You'll also need a 2-piece billet e-shaft, as the stock e-shaft actually flexes at higher rpms. You'll definitely need to make sure you have more than enough adequate fuel. A small-diameter clutch, flywheel, and tranny that can handle such high revs are essential. Namely, a chromemoly flywheel, ultralight clutch, box with dog-cut gears (also hardened), and a lightened driveshaft (carbon or aluminum). And for the flywheel, you'll need a ballistics blanket/scatter shield so in case the flywheel breaks apart, the shattered pieces won't take your legs off - literally.

Not a bad way to spend $25,000 ;)

~Ramy

How can it be well bellow 12 18 or 20k? with a digital tac, the motor was claimed to be doing just under 20k Rpm, in an RX4.

Sounds like you know what you are talking about, but, if you say it's well below that then how do you make a Tach lie? I don't understand how this works.

Something says it's spinning 20k then I would assume that it is spinning 20k, when it says a 24V Diesel is spinning 2500rpm, and it is spinning 2500, one would assume that this thing is calibrated properly.

I'm not trying to undermind you or anything, but, I'm still going to question when I've seen screens and computers say 19,845 Rpm.

I am slightly baffled now.

Capt. Moe, I wasn't responding specifically to your post. I was referring to a regular rotary stock block. 13B's don't do well in the upper rpm range (hence the stock 7800 rev limiter). Above the 8K+ mark, you'll really have a problem w/ the heavy rotors and e-shaft flexing. 12A's can rev higher, while the old 10A's can rev well up to 10-11K stock.

I don't know anything about the RX-4s, and I didn't say what you saw was wrong or impossible. I highly doubt it was a stock block though. The car would have to be modified *substantially* to the point that you would know it.

It could also simply be a case of an incorrect lead. There was definitely an aftermarket tach on that RX-4, because I'm sure no rotary came revving that high or w/ a tach that read that high. And because rotaries aren't piston engines, if the lead is reading wrong (they're made for cylinder applications), it will be counting the revs wrong, and will give an improper readout. That's one of the tricks you have to be aware of with things such as shift lights that can use a lead from the tach (vs. the ECU). Let me give you an example.

A 4 cycle 4 cylinder engine takes two revolutions for all cylinders to fire. 4 sparks/ 2 revs = 2 sparks per revoltion. That is the same as the leading coil firing for our engines. Thus you'd set any electronic controller as if we had a 4 cylinder 4 cycle engine.

BUT, you can also tap into the diagnostics connector, or the trailing coil. If you do this, the pill value for a shift light will be half what you want the light to go off at. In other words, a 3000 rpm pill will illuminate the shift light at 6000 rpm on the tach.

If people weren't aware of this on the RX-4, the lead was from the trailing coil, and the settings were incorrect (based on a direct 1:1 reading), they would have been getting correct rpm readings for a cylinder engine, NOT a rotary. And in such a case, the 20K rpm you saw would have actually been double the actual rpms: 10K rpm. That's much more believable and likely, unless the RX-4 was an all out full race BEAST (again, you would know this from how heavily it would have had to have been modded).

Furthermore, it would be pretty sad if you were only seeing 14 psi at 20K rpm. At such a high rpm (there's not much more room to go), you'd be at the engine's peak flow, and would probably be seeing 25+ psi on a properly sized turbo for such an application.

In any case, my previous post was simply to clarify that it isn't a case of "just add fuel" and the engine will keep on revving. A LOT needs to be done to our engines to KEEP them revving high(er) for long :)

~Ramy

Thanks for clarifying.

Not so discombobulated this... err... Morning still here I guess.

Moded engine, I am not sure. He never really talked about it much.

as for the 10-14psi that was just a guess on my half because I could only ever see part of the boost gauge. (digital one). All I ever really seen was the last digit on it from the way he had it set up.

I must inquire if he's got any pictures of that thing....

Next time I talk to him I'll let you know a little bit more. Assuming I remember to ask him.

Capt. Moe, that would be cool, but don't even sweat it. I'm not calling BS or anything. If you're right, that would be amazing...and I really wish you can get pictures of that monster. And I hope others now realize that while a rotary can rev high, everything has it's design limits, and to push those limits, you have to do a LOT to compensate for the resulting shortcomings...

~Ramy

i got another question, i saw a video on here somewhere about a RX-7 (?) with a four-rotor engine. now i get with the design of rotaries you can bolt as many as you like together (within reason) but as far as i know mazda's biggest rotary engine was a three-rotor (20B in cosmo) but for more rotors do you have the crank custom made ? like cnc machined or what ? cos for strength you cant really weld two together an have a "frankenstein crankshaft" for certain reasons.

so what would you do ?

and how can a naturally aspirated (i think it was in the video) four-rotor run a sub 10 second pass ?

To tremendously oversimplify, you have to have a multi-piece e-shaft to be able to assemble the engine. Can't use a one-piece shaft. There are prob only 3 or 4 shops in the US that have ever even seen a 4-rotor, and I know one of 'em in Alabama/Tennessee actually works on them. Down under, however, they're crazy and there are quite a few shops that mess w/ that sort of thing. They also make the multi-piece shafts for 2, 3, and 4 rotor engines, as well as parts and kits for making 3 and 4 rotor engines.

As for a 4-rotor making a 10 second pass...don't underestimate a bridgeported or peripheral ported NA rotary. They can make tons of power. Ever heard of the RE Amemiya JGTC racecar? I've seen and touched it (drool) lol. It runs a peripherally ported NA 3-rotor. Here's a few pics of the beast:

http://www.rx7club.com/attachment.php?attachmentid=105175&stc=1

http://www.rx7club.com/attachment.php?attachmentid=105176&stc=1

http://www.rx7club.com/attachment.php?attachmentid=105177&stc=1

Pics don't work.

the mazda 787b le-mans race car has a 4-rotor

Pics work for me. They work for anyone else?

uh there was a 4-rotor made, pretty sure it was just two 13b's together, but ... it was called the R26... had 3 plugs per rotor and a variable length intake system that adjusted the runners depending on rpm. i can post a pic of this motor if anyone wants to see it

here are a few views of the R26J ( think i got the model right, lol)

http://img333.imageshack.us/img333/4923/26blarge5jq.th.jpg (http://img333.imageshack.us/my.php?image=26blarge5jq.jpg)

http://img343.imageshack.us/img343/879/26b35nt.th.jpg (http://img343.imageshack.us/my.php?image=26b35nt.jpg)

why do those intake pipes move up/down ? what effect does that have ? doesn't it do something to the torque, or is that just with conventional engines.

Ok, just a quick question. Are S4 and S5 window switches interchangable? For example, if I take an S4 driver's side window switch, and swap it out for my broken one in my S5, should be fine, right? As far as I know, they are - but I'd like a second opinion. Below is a photo of what I'm talking about. Thanks in advance.
http://i6.ebayimg.com/04/i/05/1b/f9/71_1_b.JPG

Take a look at the Connecting ends on both of them, if they are the same, which they should be, then yes it will work fine.

That 4 Rotor is insane, I would love to see that thing in person and watch it rip the 1/4 up. But, as luck would have it, I have nothing in the Porvince of alberta that makes me drool quiet like that little baby does.

I tried looking up the.... r26 and couldn't find anything on it. Gave me a bunch of bullshit sites and what not and just frustrated the hell out of me.

the most famous one is in the 787B race car that won LeMans in the early 90s.

also a shop in japan made a custom 4 rotor out of 2 12A's (Scoot)

The thing I would be worried about is the multi peice Crankshaft.

i believe the varaible length intake tubes would have something to do with resonance... much like a variably tuned intake, probly doesn't add much hp, just smooths out the torque curve i would imagine.
its not really a "multi-piece" e-shaft because i believe its custom fabbed as one piece. can't be much of a loser because it raced in Lemans and was dominating for years until it was banned.

the 787b was in ALMS for one year, 1991

guess i was misinformed... lol

Tuning the Torque cuvre I think would be a better advantage then adding whacks of HP.

But in the same token, if you tune your Torques bracket, wouldn't that affect your HP bracket aswell?

yes, but "horsepower" is your RPM times torque divided by 5252. so yes, tweaking your torque curve would affect your hp. and by smoothing it out i simply meant just to even out the peaks and dips (if any) across the rpm range. but then again, the variable length intake tubes could help the torque down low, when you need it to get rolling because lets face it ... a motor that has some pretty high revv's.. the torque comes in at 6500rpm... lol .. isin't going to have anything off the line.

here's a few things about that car / motor...
http://www.fast-autos.net/mazda/mazda787b.html

but here's the best one, and a 56k warning at that ... lol
http://www.scuderiaciriani.com/rx7/787B/

and here's another list of mazda engines from years back and present. sorry i wasn't quite correct about the 4-rotor model # ... its the 26b, or r26b ... just varies depending upon where you look for it.

http://www.answers.com/topic/mazda-wankel-engine


oops forgot to add the link at the end of the post, lol

Well. I don't know about that, as my buddies 86 gives her hell when he leaves the line. So, I don't know.

Thanks for the formula and information.

i have another question: if the crank is a multi piece item, how is it held together (bolted ?) and then couldn't i get hold of a pair of 13Bs from wrecks an just bolt the bits together (i know its easier said than done) an make a 26b ? and with all tuning an that what kind of power do you think could be make form a quad-rotor ? both n/a an f/i