peejay

Samps it depends how light it is!

Stock port 6p13B's have run low 14's.... and mid 14's... no problem!

flubyux2

Peej, i still have a FULL interior WITH the 2+2 seating... you know, the little *** trays in the back. sans radio, spare tire, and jack though.

another RX7 guy at the track said a guy w/ a similar car weighed in around 2700. i wonder if my car is that light...


anywho, something i wanna figure out, is WHEN i should shift my car?

how high can i safely rev My motor? (i know that rotaries are safe up to 10.5k, but then some harmonic distortion of the Eshaft causes it to self destruct or something like that) but what about a stock motor w/ 106k on it???

when i ran the car, i was shifting at 7500-7800...maybe even 8000. but i have an S4, so my redline is at 7000, according to the tach. i just assumed that its a 7000 rpm, cuz maybe the engine accessories werent designed to rotate at that high of a speed. but all i have now are the AIR pump and Alternator. will this change my ability to rev?

anyways, i wanna get that Header fabricator kit from Mazdatrix, but i want to alter the Primary lenghts to move my power peak around. but im not sure WHERE i should put it, since i dont know the RPM limit of my engine. after i can find my RPM limit of my engine, then i think ill tune the power peak for 1500-2000 rpms BELOW the redline. so when i shift, itll land me on or before the power peak, and ill have a margin of error just incase i accidentally over rev.

can anyone help???

thanks folks
chris

Samps

I meant that he had the lightest second gen STOCK. There is probably lots of second gens out there that are alot lighter than his after wieght reduction. And I was not aware of other S4 stock ports in the 14s (w/o NO2). That means that a S5 stock port should be able to do it a little easier.

relvinnian

Air pump + ACV weighs about 8-10 lbs, if that.

It may not be, it's all about airflow. Your engine is not flowing a whole lot of air (relative), so I would trust Mazdatrix on this. You need to keep exhaust velocity. 2.25" is DEFINATELY not too restrictive.
What for?
You need a dyno graph to do this. You need to find out RPM drop for each gear change, then find out which will give you the largest average horsepower for that gear. You can get a "rough" estimate with a Cartest, or Desktop Dyno program, if you have a good indication of your torque peak.

Edit: BTW, very nice times. Your car has a high 14 in it as is.

Samps

air pump itself weighs at least 15 pounds. ACV weighs nothing.

relvinnian

Honestly, I have no clue, but I've removed many, and I don't imagine it being any more than 8-10lbs. Andas you said the ACV weighs nothing.

flubyux2

ok so maybe i was a little optimisitic in the weight loss. the AIR pump is about 10 lb, and a couple more LBS for the brackets.

and the ACV is something. its bigger than your palm, and its made out of metal, so it DOES weigh something, probably 2-3 lbs. every little bit counts. i hate it when people are like "nah, thats nothing, not worth it" well the more little things that are "nothing" that you take off, the more it adds up.

and btw, my car has a GVWR of 3650, and the weight capacity of it is 680. so a dry weight of my car, would be LESS than 3000. not to mention all the weight reduction ive done so far. now all i have to do is put MYSELF on a "weight reduction" program.

I do trust Mazdatrix, i think a 2.25" exhaust will be perfect for me. actually, they said a 2.5" was about the smallest theyd put on a Heavily modded and ported NA car, for a single.

for duals, they recommend dual 2". thats interesting, that means the exhaust is the same size from the exhaust PORT to the tail pipe, using their systems.

and about the Premix, ask RETed about using premix in a rotary. the stock oil injection is mediocre at best. Ted has torn down rotaries that ran the stock oil system and had a nice looking wear pattern on the apex seals RIGHT in the center, where the oil injector fires. when he tore down rotaries that used Premix, they looked pristene inside in comparison to NON-premix engines. and i think having 106k on my motor is all the more reason to run premix. its peice of mind.

thanks
chris

Anderson

How much premix should be used in one tank??

relvinnian

I was just playing devil's advocate

Sounds like you have a plan, and a head on your shoulders so I'm sure it will turn out well.

Good luck, and nice car

Bambam7

79 octane?? I wouldn't.. not if you are going to lean it out!!!!
Definately to the OPPOSITE of what you did on the MAF- 99% of FC's will benefit from leaning out quite a bit.

Advance the timing up just a tad...
port the intake manifold- that's OK....
For your exhaust... a single 2 1/2 is the best... you may loose just a touch of low end, but the high end will more than make up for it.
I'd go with a bonez race pipe over headers.... you will only gain 2-3 HP with headers on a non ported car, and the noise increase will be nutty. You'll hate it. But if you do get headers, DON'T EVER GET PACESETTER!!!! They are cheap, and they fit OK (sometimes) but they sound horrible, and are not equal length- they can actually COST you power over the stock manifold!! ($100 for a slower car thats louder... cool)
Racing Beat is OK though- if you are looking to squeeze every last bit out.
BTW- impressive numbers for a stock port- hope you didn't fudge 'em.
Keep it up!

relvinnian

I agree. Do not run lower octane. If anything run higher octane, with more spark advance and leaner mixtures.

RETed

You're right - a 1987 Turbo II air pump is slightly under 9lbs.; I would imagine all the other "variants" not being that much different.
http://fc3s-pro.com/TECH/weights.htm



-Ted

flubyux2

for our cars, you use a 1:100 ratio of oil to gas. its like 13 Oz for 10 gal of fuel i think. our cars use about 1 quart of oil from the crank case every 1000 miles. but as Ted has told me before, the stock oil metering system is nothing to brag about, tahts why i want premix.

side note, i noticed that upon cold start, my engine started right up, and smoothly revved up to 2700.. normally it would sputter up to about 2000 or so, and then id have to tap the gas and then it would settle out. and then idle at about 600. i think the premix DOES help.

ive Read about Mazda's IMSA/GTU race team using 79 octane as "Race Gas" for their championship cars. i think they were FB's, back in the early 80s. so if they ran LOW octane when everyone else was running high octane, i think its safe for me to race w/. everything i know is based on a world of pistons, so i might as well throw that out and stop adhering to conventional thought since its mostely piston-based.

think about it, lower octane fuel is Less stable and more volatile under pressure. this is bad for piston engines since you cant have combustion starting where and when its not supposed to, and you KNOW where the fire is supposed to start, stay, and travel to, in a fixed chamber, such as on a piston engine. but, rotary engines have dynamic combustion chambers. the flame front and combuston chamber is constantly moving and changing. it only makes sense that you want a fast moving flame front to aid in the rotation of the rotor. if you have HIGH octane fuel in an NA, that means its a slower controlled burn, which keeps detonation in check. this means that the combustion/flame kernal is going to start and radiate outward from the spark plug, and wont move as fast as lower octane fuel. i read about the Mazda team using Low octane "race gas" in their IMSA race cars on http://www.scuderiaciriani.com/rx7/information.html its the most in-depth site ive found as far as rx7 info and background.

also, i was always told NOT to try to monkey w/ the timing, as the computer knows where it should be and will simly adjust it back to the preprogrammed settings.

as far as my future mods:

Mazdatrix Fabricator header kit (i think i can do a better job than some other professional companies)
Mazdatrix slip on Y pipe
Pineapple 6 port sleeves

ill keep my 2.25" exhaust since itll allow me to keep some low end. BTW, i dont know if you actually READ my previous posts, but i Dont have any real cats. i Have a race pipe. its 60mm. i have my manifold leading into Precat 1 Gutted, then basically 2.25" exhaust from the gutted cat, out to the muffler. there isnt much improvement to be had by installing an expensive race pipe, if any. even if a header only adds 2-3 HP on a stock port engine, every little bit counts, and i cant think of many other ways to up the HP in a simple and cost effect manner. i want to make the most out of my engine w/o having to tear it down.

i know about pace setter headers and their wonderful quality control.

and i dont really care about noise, i like noise. my saying is "if its too loud, your too old" and i even have a sticker on my hatch saying that.

anywho, what should i try to tune my car by???

EGT, AF guage, or what???

im used to .95 O2 voltages for being a nice rich mixture at WOT.

and on turbo piston cars, EGT temps should NOT exceed 1600*F or 900*C. but rotaries are way different. so what should my guidlines be as far as tuning by EGT?

i could get an hour of dyno time for $100 and get my car dyno tuned, but dont you think there are better ways to spend that $100, like put it towards my next upgrade?

thanks guys
chris