FB II

ok so now i have two friends that just got stock fb's. i've driven both and realized that, in completely stock form these cars are pretty quick. their clutches are alot better than mine so it feels a little better engaging in to gears. my question is... i have the mods listed in my sig and when i compare driving mine to theirs, the difference only seems to be the power band. all my power is from 4,000 to 7,500rpms where as theres is more down low, but doesnt really pull over 6,000rpms. but the overall acceleration seems almost identical. i dont get this. my compression isnt low, my timing i think is off (havent checked yet), my clutch isnt that great right now, but still. my car should be owning theres. the only time my car shines is if we're on the highway together side by side. from 5,000 up i can own. THIS SUX. is this the exhaust? i noticed all pre-made exhaust systems are 2" piping diameter. mine is alot bigger except for the rb header. anyone got a take on this? sorry so damn long.

timmya2

wat engine are thiers?

13bts?

wat year?

u sure its completely stock?

how much miles has it done compared to yurs?



wat muffler is that? did u modify it to make it fit the rb header?

also might be a silly obvious question.. but ill ask anyway

do u open yur secondaries at low rpms?

and wat motor is yurs?

FB II

it's all 12a's. mine actually has the least amount of miles. one of them has over 200,000. still runs strong. i have a turbo muffler that has been welded to straight 2.25" piping that is connected to the rb header thru a flange. no leaks. i usually open my secondaries at around 3500 and it pulls pretty good. no bogging. it just doesnt feel any faster. hahahah, for such an amount of mods. i really think my timing might be off though. could that make a difference in my overall rpm band?

edit: also, i know for a fact they are both stock w/ the cats and everything; except one doesnt have the clutch fan.

RXRACER85

FB II
i can see your gas gauge does not work? Same problem here if you find the problem let me know and ill do he same! but as for your power i think you should own to but more that likely it's a timing thing so try and get it fixed so you can kick some true a##

mazdaverx713b

iTrader: (91)

if the wires on the connector at the sending unit on the gas gauge are good(maybe clean them) then fill your tank up and smack the tank in the center with some good force. usually the sender is stuck and frees up. maybe try smacking it while you are filling up. it sounds crazy, but it has fixed two gas gauges of mine!

MosesX605

I find rotaries to be very deceiving when it comes to speed. I've driven several 12A powered 1st gens, Manntis's SE and deggail's 2nd gen. The 13B cars didn't seem too much faster than my 12A cars, or the other 12A cars that I've driven, but one look at the speedo and I could see the difference.

RacerX7fb

This is why after smogging my car my header has been sitting in the garage
Stock exhaust manifold into a custom connector pipe to RB presilencer (RB has this setup for FCs)... MORE bottom end than when the header was on (Ive been using RB headers for almost 10 years) there is a difference..

Being mostly a street car first and sometimes track car, its more enjoyable to drive right now having more bottom end power.. gas mileage has also improved some since I dont have to get on the pedal as much to accelerate just as fast.
When I start doing more and more open track events the header will go back on though for peak horsepower, since that is where driving consistantly at redline/WOT is done.

AdrenalifeRX7

You might possibly be losing some low end torque by having a more open and free flowing exhaust and having less backpressure. By doing this you are opening up the top end of your horsepower in your rev band. Your friends must have more restrictive exhaust setups and most likely that's why they can pull easier at lower rpms but tone down a bit close to redline. What I'm saying is they might get you off the line...but in a top speed run you will probably catch up at higher rpms. Number one rule: Rotaries are EXTREMELY sensitive to exhaust modifications.

FB II

yea, definitely sensitive. since i have mech. secondaries, i've been playing around at different rpm's of where i open them up. for 1st and second gear it seems good opening them in between 3,000 and 3,500rpms. 3rd on it's better more close to 4,000. this is ofcourse just cruise driving. not opening them and going to 7,500. hahah, but when i all out race and whatnot, it's rediculous because my clutch won't hold it. if i stomp it in first and slam in to second full throttle all my clutch does is slip. puuuurre slippage. it feels like it just wants to tear *** though, cause when it finally catches it's pretty nice. i've thought about going back to the stock exhaust manifold and connecting that to my straight thru exhaust like Racerx7fb did. seems my hypothesis of the power is correct. one thing though, Racerx7; does it still pull pretty good up to 7,000 and up? if so, my rb header might be up for sale hahaha, this is definitely a street car...... with the occasional race or 2, ... or 5.

FB II

oh yea, about my fuel gauge; one of the prongs on the sending unit is busted off. i thought maybe if i grounded the wire out it would still work, but nah. :/ i guess i need a new fuel gauge sending unit.

Rx7carl

Your large exhaust dia tubing (its dual 2.25?) is part of it, also how did your port your intake manifold? That is also a contributing factor.

red13brx7

You should definitley fix your clutch problem. That will help a good bit actually.

RacerX7fb

Yes. I'll let anyone take my car for a spin so they can see. There is a hint of the power flattening up there, thats also due to the design of the stock SE intake.
Maintained 8000 RPM and almost 100 MPH down the straight at Buttonwillow Raceway recently..not too shabby for a nearly stock 1st gen... new M3 blew passed me though

Ive used 3 different exhaust configurations over the years using bolt on components and here are my findings:

Stock with cats and RB muffler... clean and quiet, good bottom and mid range but crappy response and definately lacking power in the top end.

Stock exhaust manifold to custom downpipe to RB presilencer and RB muffler... my current setup, better bottom end and midrange and a gain in top end. Good response too. Deeper and quieter exhaust note than...

Full RB headered system... loss of some low end, good mid range and best for high RPM and peak power.

Next I will be trying a header to high-flow cat combo... gotta do what I can to try and maintain a good noise/power level/smog legal car here in Cali that suits my purposes, mine being mostly street and occasional race.

Typically headers will move the powerband higher up the rev range the farther back the primary pipes collect on a car.

Again these are my findings simply from by experience driving my own cars over the last decade and learning from those who do prep and race cars on a Regional and National level.. I am no guru by any means, I just like to have fun like the rest of you

Rx7carl

Well written! Goes along with my experience also. It was really noticeable when I switched from a short primary to a RB SP exhaust. Since its an automatic (stock ported motor), the loss of bottom end was very apparent, but the gain in mid to top end was very noticeable also.

Directfreak

iTrader: (2)

Carl, Your car has a slushbox?

Rx7carl

My daily driver does yes.

Sterling

FB II

yea, my rb header collects way back, seems around where my passenger seat is. :/ i'm gonna try the stock exhaust manifold with straight piping and see if i like it better.

mazdaverx713b

iTrader: (91)

it will work with one prong busted off! mine does suprisingly!!! it's only a ground. you can ground it. it will work! try smacking the bottom of the tank before you replace the sender. it may take a few good whacks.

FB II

awesome, i'll give that a shot! hahaha, i hope so, cause i've already been stranded once ahahahahahhahahaha

Rx7carl

Rx7carl

Youll probably find that itll pull alittle harder, but run out of steam at 5-6000.

brianw

What's a slushbox?

mazdaverx713b

iTrader: (91)

my definition of a slushbox is an autoamatic trans.

brianw

AAAH!