LookThatsMe

hey guys i have a question... I have an 87 Rx7 Na... i just got it bak and i have and k&n intake (i know the price is highand i hope it was worth the money for the intake) and an Borla Supersound exhaust the car sounds really nice... if i bring it it up newere between 3 1/2k and 8k rpms it backfires but i dont see flames is that normal... this is my first rx7 so i dont really know alot but i love it... also my friend goes to a tech school and his friend has one same year as mine and he runs his car on 97 octane.... neway he said he brings the car up to like 14k rpm because there is no rev limit and he said it sounds crazy is that tru that theres no rev limt cuz i dont want the worse thing to happen and blow my engine... help me out guys

LookThatsMe

ohh yea and one more thing my shifter is so loose it all over the place, im not sure it it would be the bushing or i need a new shifter... i want to do short shifter ive seen one for sale but it didnt come with the linkage system so im not sure if that would work... i mean the shifter is so loose that you cant even tell the diff if ur gonn put it into 1st or 3rd... help me guys

midnight_7

ur not shooting flames either coz u still have ur cats or ur not running rich enough.

14K rpms? how? the octane level will not dictate how high an engine will rev.......only way he revs that high is if its a purpose uilt race motor. think F1 cars....

BlaCkPlaGUE

lmao, 14K, are you sure? I mean I thought the redline was like 8000rpm, and that is right at the redline wich I wouldn't even recommend getting to in the first place.

RotaryBuddha

iTrader: (4)

unless he has got some mad hatter Peripheral Port he is not able to rev to 14k and still have a motor.

ultradef

- You will usually not shoot flames unless you remove your cat and replace it with a presilencer or a straight pipe.

- N/A owners usually recommend you run the lowest octane you can.

- There is a rev limit on a rotary, it should be around 7500 rpm on your car. Without extensive work to the engine and drivetrain, you cannot safely rev higher than the stock redline. Besides being very dangerous, it is also not beneficial, as the car will not make any more power that high without serious porting.

- Your shifter problems are most likely caused by bad bushings. They tend to break after time and cause sloppy shifting. You can either order new bushings (I ordered mine from www.mazdatrix.com) or you can order a short shifter if you were planning on doing that anyway. Just make sure the short shifter comes with all the bushings you need, as some do and some don't.

RXciting

lol there's no way the stock engine would be able to breath at 14,000 RPM's, even thought it probably would probably have a nice sound up there

an s4 (86-88) RX-7 has a redline of 7 (which i go past quite often when pushing it in my 87 base, but i have the mods to be able to breath up there) and we have fuel cut at 7600 or 7800.. anyways just b4 8000 so if he has an s4 with stock ports and stock ecu i doubt he's hitting 14,000

he's running 97 octane?? are you sure you don't mean 87? cause if he's running 97 he's wasting alot of money cause an N/A RX-7 runs best at 87

You have to replace your shifter bushings.. i don't know any second gen RX-7's that haven't had a lose shifter at some point in their life.. including mine

so on this guy i must call

Frank

DerangedHermit

Backfiring... could that be caused by a misaligned TPS? Someone with a brain that didn't wake up 3 hours earlier than normal.

Kenteth

Its clear you've never seen my video of me burying my tachometer past redline, pegged still making a shitload of power still in the powerband-- WELL beyond 7.5k. Stockport N/A mind you running 85 octane. This 7500rpm rev limit is trivial as its there on some cars, other cars seem to rev right past it. There is technicaly a fuel cut to the rear rotor somewhere around 8.5 or 9sh though... But my car makes power FAR beyond 7.5k.

That said, the author, or the author's friend that grabs "14k" is telling bullshits. If by 14 he means 8, then yeah he probably gets 14. You know whats funny is the kid probably doesn't even make power at 8, but has to talk cool about how a rotary has no theoretical physical rev limit, so goes around thinking he COULD make 14k if he had $50,000 to invest in an engine.

take a physics class, at some point your realise the cetrifical force pushing to the side of the engine is enough to shadder the apex seal through the housing, and shadder the rotor.

Your techie buddy is telling you a long fledged lie. Tell him you want him to see his aftermarket tachmeter ( a pretty expensive one to reach a reasonably accurate 14k) show 14k. The flywheel will bust apart at like 12k ripping both your legs apart and ****. Wahtever, take the highschool... errm "vocational school" **** elsewhere.

EDIT:
Oh, and if he's running 97 Octane on an n/a he's a dumbsit. N/A's roll far better with the lowest GAS octane you can find. Typicaly its 85 for me. Why gas octane? Because diesel octane is like 45 something, but its diesel and we don't live in europe.
If he's running a turbo, the 97 octane MIGHT be justified. But if he's running a turbo, theres no way in HELL he ever gets anywhere NEAR 14k, not like he is anyway..., but if he has a turbo, he for sure as hell isn't doing it.

CyborgRyu

iTrader: (8)

Can rotarys run off diseasl?

Kenteth

this is a dead horse, go search.

SecondgenRX_7

at 14k you would need such perfect balancing on everything, the slightest woblle would be amplified so drasticlly youd launch your flywheel into a million peices. You need full balistics sheilds over your tranny for that type of operation.

My 87 stock n/a will redline at 8k i start loosing all pull after around 6.5k. I have no cut off in mine, problly doesnt work like half the electronic controled stuff in my car.

Yu cant bash all the techy kids, i was one, but it always seems the auto kids bs more than anybody. You got to have all the kids with there 5 second camaros, and junk mustangs

LookThatsMe

thanks alot so know i know its bullshit... neway as i said i have only intake and exhaust, what could i put in it to pull get more power without the turbo price... im also looking for a s5 TII...

Aaron Cake

iTrader: (1)

I would be very interested in seeing this dyno sheet.

RXciting

could be his dropoff just isn't as bad by that RPM but that wouldn't make sense if it's still stock

i know my peak right now with a straight dual and cone filter and stock ports is just b4 or after 7 (most likely b4) but it still has usable power to pull it till i hit the rev limiter, and it hits pretty hard to tell you the truth Aaron,

but i'd like to see this dyno sheet as well..i thought the rev limiter was built into the ECU?

Kenteth

Aaron knows the engine isn't stock. I said Stock ports.

Removed emissions/ps/ac/air pump/cats/acv and *working* 6 ports and vdi make the difference. I can definately feel the difference of the VDI. When it works, I rev straight to 8 and past (though the tach pegs,) There is a high picthed noise that is associated with it. Project84 said it sounded like a turbo spooling, but this is from the cabin, outside I'm sure all you here is exhaust.

On the other hand, when the VDI doesn't open, but the aux ports still do, I can still rev to 8, but I'm exiting the powerband right when i touch the 8 mark, and it doesn't get their quite as quickly.

See: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/im-powerband-8krpm-bad-video-337676/

For the one video and a couple picts of the engine bay, I've got a couple others that aren't as jumpy though

And I'm thinking of reserving some dyno time next month. How do I go about doing it? Do I just tell the local dyno shop that I want a base dyno stat so I know where I'm at? Any idea on what the going cost is, and about how long it takes to get a good dyno run?

inflatablepets

14k Hmm... What about stationary gear distortion and eccentric shaft flex?

Icemark

what are you using for an ignition controller and coil set up, since the stock ignitors and coils pretty much are breaking up pretty bad by 7.5K, which forces the power down no matter what.

xfeastonarsex

iTrader: (5)

you and your negativity...
http://gltrs.grc.nasa.gov/cgi-bin/GL...CR-195395.html

Kenteth

Stock ignition... actually. I always thought the ignition was pretty decent? Maybe this is an upgrade I should consider. I'm not extremely familiar with the ignition systems as I want to be. By ignition controller, an example is an MSD-6 right?

Just being realistic is all. If I had NASA's funding, I'm sure I'd find a way to make a diesel rotary too...

---------

BTW: I doubt it really ever made too much a differnce, but the manifolds are gasket-match ported, and there is a full TB mod done, (regretfuly, wish I kept the termalwax now)

Impreza2RX7

Some people need to stop kidding themselves and take a trip to the dyno.. Just because it feels like it's pulling, dosen't mean it actually is..

Kenteth

Thanks for the input...

Impreza2RX7

Sorry pal, I missed that.

Icemark

Yeah the Stock system is excellent up to a point (usually 6.5k) which for most drivers is fine. But I noticed when dynoing my 'vert that the spark break up was one of the limiting factors in getting above power above that (as well as the stock intakes run out around 6.5 k on a S4 and 7.5k on a S5 non turbo).

MSD 6A is a good choice, I have also had good luck with the Mallory Hi-VIa. They will stabilizer that upper rev range spark.

Stock coils though.. they are just as good as anything aftermarket.

Kenteth

So the coils are decent, but its just the controller (ECU?) that makes it choppy? I guess I could see that happening. I will definately look into an ignition controller soon, I throught the stock system was great from what I always read. I guess by system though, they meant the coils.

No worries, just curious how much this might cost-- I don't want them to say some outrageous amount and then me be like "great, lets go"