One320B

I have to agree w/ j9 on the collecting exhaust debate.



I've run both true duals and collected. My personal preference, and the setup i plan to run on my 12A NA big bridge is uncollected until AFTER the presilencers... this should give the best torque at midrange (coming off corners) and not sacrifice too much top end on the straights.



True dual does give the best all out top - but unless your racing at revs above 8K in 4th gear all around the track - who needs that top end. I'm all about the mix of good midrange torque and plenty of top end left before the next turn.







My opinion on the ECU setup - megasquirt for the cost would be your best bet, but you can run the LT8s cheap too (just get a newer model, we've had issues with the older ones not adjusting timing AT ALL)...

RotaryVillain

check ebay and the forsale forums here frequently individuals sell Haltechs already wired up for rx7's (taken off their own car)



oh, and like the other guy on here said, Done Properly Your Gonna Be making more than 200 hp

Aurosting

the motor is an 88 s4 but the chassi is and 89 s5....i was at the racing beat website and i think the true duel exhuast is meant for a 6 port motor not a bridgy 4 port

RotaryVillain

back to the collect vs. uncollected

Look at the header for the MFR PERIPHERAL Port and tell me whether its collected or dual...thats right its Dual , now think about it. the PP housings flow way more then conventional rotor housings , so



also i dont think its matters whether your running a 6p or 4p bridges, because as im sure you know the rotor housing exhaust pattern is the same anyways.-0 and regardless you will Never flow more than the diameter of the round tubing on the headers , look @ your exhuast port.-0 my own .02

anewconvert

And where is the powerband of a PP?





Now, where is the average enthusiast RX7 driver going to spend the MAJORITY of his time? 8k+ rpms? Or between 3000-7000?



Maximize the powerband where you are going to spend your most time. If this is a track car that will spend the vast majority of its time at very high RPM then tune your exhaust for that. If its not then mid-rpm power is where you should be tuning for.



BC

j9fd3s

the MFR system (from 1979!) is collected. it collects by the rear axle, not by the engine. http://www.racingbeat.com/resultset....rtNumber=16422

http://www.wankel.net/~krwright/files/manu...x7_comp_man.pdf



longer the collector the lower and broader the power band



the shorter the higher and peakier the powerband.

RotaryVillain

first of all if i remember corrrectly the first gen cant do and true dual system due to the placement /size of the stock gas tank.

so using that example sa a comparison doesnt work. the pic of you racing beat exhaust exactly LOOk at the Racing Beatone for the second gen that i posted!!! we are talking about second gens where there IS room for dual muffler exhaust!!!

1st gens cant run dual (stock straight) thru anyways so Of course they are ALL collected!



the guy is driving a 2nd gen! with a Bridgeport engine (not a streetport)

dont forget that.



(not a 1st gen with a streetport, theres a big difference)

http://racingbeat.com/FRmazda2.htm

RotaryVillain

cut & pasted from the true dual exhaust stystem for fc. (RB)



Racing Beat offers a true dual exhaust for all models of 1986-92 non-turbo RX-7s. This complete bolt-on system utilizes all of the stock hangers and hanger positions. Although this system can be used on "street" applications, maximum performance benefits will be realized from cars with intake, ECU or porting upgrades





now if You guys wanna argue with racing beat you can call JM and tell him what youve Researched lmao

read it in Their own words.

*notcie where is says for MAXIMUM BENIEFITS with Porting and ECU upgrades!," how much cleared do you need it j9! lmao



have a nice day.

class is dismissed.

j9fd3s

theres plenty of room in a 1st gen for a dual, ive seen a few of em.

Hyper4mance2k

Hate to tell you Villian, but you're wrong. For maximum power on a NA bridgeport or a Periport. you want a collected exhaust. A properly setup collected exhuast uses the exhaust pulses to suck the exhaust and scavange out the next pulse. I think in a 2" primary exhaust you want them to collect after 82" or something. On racingbeats website they state that the true dual is only for street port or stock port systems. Pick up Mazda's factory tuning manual from the FB periport days and you'll see they even used a collected exhaust. You're plenty wrong if you don't think a FB cannot run a dual exhaust. You really need to read up on exhaust velocity, scavaging, and flow charictoristics before you go and yell at people.