Suprising, would've thought they'd use something a little better.

 

SO here is my sudo expantion camber. 30" long primarys, 2.5" collector to a 3" section back to a 2.5" and for now straight out to the turn down before the Axle.

For now my set up is: stock port 12a modded nikki, stock intake and RB header.

I'll be adding a Weber 48 ida asap (may be looking into a nikki/rb holley intake set up)

Looks like after this race I will be on the dyno. If the numbers are what I would like. then I will make a copy of this in SS complete with a burns stainless colloctor and muffler.

 

Hyper4mance2k I should have some dyno sheets to post online in the next few days so you wont be the only one pushing a stockport 13b to its limit. The engine was built to street prepared rules.

gslse stock port
full racing beat long primary exhaust
50mm twm throttle bodies
Stock 2nd gen coils/cas/ignition system
e6x haltech

I was wondering if you had any egt or timing advise. If I had a distributor id just lock it to 20 something degrees and call it a day but with efi bleh. I may still lock it if no extra power comes out of tapering it off at high rpm/loads

 

it you're actually on a dyno, and a new combo, keep it simple

i would make the AFR rich like 12.2 across the board, then try 12.5, 12.8, 13, etc etc. you can then lay the runs on top of each other and see what it likes best.

timing is the same, i would start around 20BTDC L with a 10 degree split, over about 2500rpm, and then try 18BTDC L, then 22, etc etc. if you start laying the dyno runs on top of each other, the engine will tell you what it wants.

EGT isn't critical, assuming the probes are 2-3" from the engine, keep the EGT under 1000c. best power should be in the 940-950c range.

 

so if i were to build my own custom exhaust system what are the absolutely nessicary parts.

this is what im thinking of

RB RR header
header gasket
megaphone
rev 30
and perhaps the rr outlet flange for fabricating a collector if needed



if i were to ommit the pre silencer how would that affect performance.. and i plan on using 3ida pipe after the megaphone.

or should i forgo the megaphone and run true dual into two glasspacks? (it'd be the cheapest way LOL)

im totaly new to this and am looking to spend maybe 500 or so on parts (not inlcuding tubing)

 

How well do these megaphones and collector solutions perform at actually muffling the sound? Or are they loud -- ticket-ready bait for the local law enforcement?

 

From what I've been reading elsewhere, a proper merge collector arrangement will make a kind of acoustic choke that decouples the header from the rest of the exhaust system. The short version is, once the exhaust is past the collector, what comes after is is not very important for flow, so it can be made quiet (restrictive) without hurting power.

I've noticed that modern engines have manifolds/headers that look suspiciously like merges, and people are claiming that longtube headers with "old think" collectors (dump 'em all into a big pipe) will net a power loss unless a free-flowing/loud exhaust system is used.

Rotaries are a "special" case (take any meaning of special you'd like) in that the exhaust energy is just so sharp-edged and powerful, but the theory's still the same.

 

it sounds like rotarys are exceedingly hard/confusing to tune a exhaust for due to fast component degredation and flow charicteristics

 

we're overthinking it too...

 

+1

 

Progress is never made by underthinkers!

 

ok, well i was just going to cut the 2 pipes on the dyno until my car makes power... but if you wanna go the other way, you need a helmholz chamber! or maybe 3, treble, mid and bass, like my guitar amp

or how about a pulsation damper before the muffler?

 

Like S2000s have?

 

It will probably leak though. They all do.

 

yep!

 

Mines not complete yet but I just wanna say the RB exhaust/header wasn't your problem.

I don't have a full on redline pull as I'm getting some rpm bounce due to noise but I'm making pretty good power.

 

I hate where people are always trying to take this thread with out knowing what they're talking about or not even reading the whole thing...

 

i have a dead FC rotor housing, and i checked the port match between a stock FC manifold and the exhaust sleeve, and then the RB header.

we always hear that the RB header has its bend too early out of the engine, and its true, the bend makes the port match pretty lousy. its hard to explain, but it makes the match at the sides of the port weird.

 

I stuck the Genuine Racing Beat Header on a 13B in order to convert it from a 12A header to 13B and noticed that the tubes are smaller than the exhaust ports. Maybe this is only a problem when using 12A parts on a 13B, I've never paid attention to the exhaust ports 12A vs. 13B or held a 13B header. But the header needs to be ported before I install it.

I am, in fact, only going to be using the front section, and may not even do that given that I have a Sorento downpipe that looks like it can yield two rotary header stubs...

 

I measured my backpressure last night. It ramps up from zero at ~4000rpm to just under 4psi at ~6500 and stays there through 8000.

This has me really depressed. That car's way too loud as it is, I don't want to have to crack the exhaust open even more...

 

I hear ya (well, kinda after all my ear damage). These cars are hard to drive on the freeway.

 

thats not too bad actually. did you notice the butt dyno drops off according to the gauge?

 

Not really. But the thing is so slow, it's hard to tell. There's no discernable powerband.

I have a hard time believing 4psi is acceptable!

 

Probably not when there isnīt mass flow increase from 6500-8000 rpms Its safe to assume that VE% at top end is lower, but such exhaust pressure gives it another magnitude...

 

No chart still

180 rwhp 120ft lbs

Im a little disappointed but it is decent numbers, not sure why the torque is so low, maybe the lighter clutch/flywheel/driveline stuff.

19 degrees of timing made max power, seemed weird to me 21L-26L with a 10 degree spit has always been what I understood to be the best.

Ill try some different things hyper exhaust wise did and report back on the results, probably be a while.

The dyno owner indicated that the readings may not be 100%, he didnt think it read the ignition quite right in relation to what was happening on the graph, beats the hell out of me, this is my first dyno experience.

Just knowing your car is fast and being happy with it that way is way simpler than all this crap.