Today I imagined what type of exhaust to do. I have to choose between a full RB "streetport" exhaust or a 3" custom exhaust. Decisions decisions. Then I decided to be selfish and try them both.

It's supposed to be a daily driver so I want power but not a lot of noise.

I think the only way to satisfy my curiosity is to try one exhaust after another. Then report my findings. But it'll take a while. Gotta throw something on it to test run to make sure it runs first.

3" could drone, a lot. Or it might sound ok? The RB, on the other hand, sounds great but everyone says it's restrictive.

Yeah, I think the only way to be sure, and not kick myself later, is to try both exhaust systems. Then I can put to rest all these little voices.

 

Doesn't it suck to know what you gotta do...and sometimes not have the ambition to do it...?

 

Continued dressing the block with front stack, water pump, sensors etc. Had a couple derails where I had to McGuyver new life back into my aged oil level and #1 water temp sensors - - old, brittle insulation on the wires needed some external support.

Finally talked myself into doing the intake water path blockoff, & got the plugs in OK.

Was almost ready to start putting the clutch on when I realized I had no pilot bearing installed; that would have sucked. Hurray for checklists.

Took a while to get that little gizmo drifted in. Then I ate some corned beef and cabbage & had a beer. Erin Go Braugh!

 

"Doesn't it suck to know what you gotta do...and sometimes not have the ambition to do it...?"

My thoughts exactly. Fabbing up a long primary exhaust takes a lot of ambition compared with just a simple 3". Plus who knows how the long primary would really work out in the end? It's one of those unknowns that someone needs to step up to the plate and test for the rest of us.

My REPU's long primary exhaust was a very ambitious project for me last year. I'd never done one before; its previous exhaust was just a little thickwall 2" single pipe with an RB collected header, and that was very ambitious when I built it a few years ago. It needed to go because it had no high end and its low end wasn't all that great. The engine wanted to breath with a Camden on it, but couldn't. So I prepped mentally and prepped the parts to be used, then went for it.

I started with an RB road race header so I wouldn't have to add a header fab along with the rest of it. Then I tacked two repacked RB presilencers together side by side (not the staggered arrangement of RB's "streetport" center section) and held up with a floor jack. Also lifted up an RB powerpulse muffler, turned backwards so the two outlets became inlets and the single 2.375" inlet became an outlet close enough to 2.5" to work. The RB hangers worked better this way on the REPU hangers too.

Once all the big parts were in place, it was just as simple as playing connect the pipes with pieces of thickwall RB u-bends and straight pipes, all in .120" thickness for noise control. The trick was in getting the pieces to fit in a 3D environment after cutting with a 2D saw, if that makes any sense. There were interesting angles everywhere. They had to be right otherwise you'd get flow restrictions. Some fudge factor was inevitable, but I think I did ok.

After the center section was done I test ran it. You know for a complete RB "streetport" exhaust system, this was way louder than it should have been! Why? Because I deleted several key quieting features of the RB setup. Mostly at the powerpulse muffler itself. I won't list them unless somebody wants me to (if you're thinking about doing something ambitious with one of these mufflers, just say so).

So since I had plenty of room for another muffler after the rearend, I added one 18" Magnaflow 5x8 oval with a 2.5" core. This made the exhaust Too Quiet! Also there was a strange amount of noticable bass in the cab. Now the cab size itself is just right to resonate deep bass, and probably the reason Mazda went to the bigger cab for 77 and later trucks, to make it subsonic. But the early cab is very bassfull. And for some reason, either the powerpulse muffler or the dual presilencers side by side were making a lot of it.

What was the solution? Well, I decided to swap out the road race header for a clone made from a dissassembled header kit. I think I got the measurements right because it seems to fit a little better than the roadrace did. The other big change was swapping out the powerpulse to an RB universal 2.5" muffler. This required an actual collector instead of letting the powerpulse collect internally. Just barely had the room for it.

Turns out letting it collect internally or maybe something else about running the powerpulse backwards was causing all the bass problems, because now the cab sounds fine inside. It also has just a bit of volume and tone out the tailpipe! Perfect! Couldn't be happier!

Another nice thing I discovered during the first test drive on the updated exhaust is it seems to have more low end torque now. I seriously doubt it's a mental thing from having just swapped stuff around and expecting big things. I honestly feel more power from it. Like it's got an actual supercharger in it where before it felt like it had a pretend supercharger.

Of course it's a fresh rebuild with 3 miles on it, but I'm wholly impressed so far. Not 3k. That's three with a capital TH R double E.

 

^Awesome story, good luck with your setup! I'm looking into doing an exhaust on my RX7 as well.

I got my 7 driving and home today. Couldn't be happier

 

For the Efan discussion above: First gen MR2 fans work great. Installation takes only a few minutes, and they fit. Lots of info if you search.

Today I got some work done on the GSL (sort of). Confirmed that no gas is getting to the carb, but I did have it running for a minute just by pouring some down the carb. Started right up!

Found PO modified wiring to pump under the bin, so I yanked that and plugged in the orirignal wiring. No go. Jumpered the relay. Got it! Gas running into the jar now from the fuel line. Hooked it back up, cranked her over, and there was a flash somewhere and no more power to the pump. Ran power direct to plug under bin, but no joy. Shoulder is hurting too bad to crawl under the car tonight, so I continue to procrastinate.

I did get to Home Depot and pick up some rust fixer uppper stuff. Got a few spots to touch up, but lucklily nothing major. Interior is perfect, but smells musty.

 

Saturday i changed a thermostat and put gas in it.

OH YEAH, and this



and this is why

The owner before the guy i bought this from hit a fire hydrant. Did no structural damage what so ever, just destroyed the fender and ripped the bumper cover.

 

I pulled mine out and gave it a bath:

 

I looked at my assorted bits for about 5 minutes, planning tonight's antics.

 

I put the front suspension on GC camberplates, GC coilovers, Advance design struts, all new lower ball joints, tie rod ends (inner, and outer). put the front brakes on the car with new brake lines and pads. Its finally a roller after sitting for about 4-5 years.

 

Tried in vain to locate a source of JIS M10x1.5 14mm-width Grade 8 hex nuts. Even McMaster-Carr was no help.

 

Seriously? Mazdatrix sells OEM exhaust nuts.

 

8134-40-355! (you should double check the part number, but its just the OEM nut...)

i think BMW has a copper version also, i don't know the application, but the part number is probably 11187657839375938759395739385739292475728394020859 302 (<-- its funny if you worked in parts)

 

what i did today? i made PP noises while grocery shopping...

 

Didn't even look there... Too used to seeing NLA on everything I want to buy over there... or prices with too many digits.

Gee... and only $4.67 a nut. Plus shipping via UPS (they won't use the USPS). Plus 2% credit card surcharge unless I want to send them a check... or burn $10 worth of gas driving there and back.

How nice of them... seeing as they should go for something like 25-50 cents each.

Thanks for the goto, Jeff... but I think I can do better on that price. Just gotta find the right source.

 

Got a set of halogen lights and heavy duty harness in from Black Dragon. Added it to the stack of stuff sitting in the garage for me to get to later.

 

Got my clutch master cylinder installed and the clutch bled. Part was sourced from rock auto...sachs, but why were the studs like almost an inch longer than supposed to be?? Its already a tight fit on that upper stud with a deep well 12mm socket, but with these long ones I barely had enough clearance to snug the bolt...(i'd still like another half a turn out of it just because) but yeah...it's in...now onto filling the gearbox and rear with some oil and this thing will be ready for a quick spin around the block!

 

^swap the studs.

 

Divin, it's been a while since I last looked into it, but I don't think they do the 2% thing anymore.

 

It's still on their website, but who knows? Maybe they only charge it to people who annoy them.

Oh, wait...

 

took my first ride in it today...it was fun! Let me know there is a ton of work to do still. Oh well.

 

use the new one there so clean you can get it about 98% tight with just your fingertips. and make sure you tighten them before attempting to install mines were loose and found that out the hard way after i already attempted it for the 3rd time lol

 

Thanks Rotor...I went after it again today and got my 1/2 turn I was looking for...all is tight and working well

 

Looks like drop-in day will be tomorrow night.

As she sits:



Amazingly, I got the pilot shaft lined up and the housings mated exactly on the very first stab. Never happened that way for me before. A good omen, I hope.

 

^A thing of beauty^ I finished up my door panels last night, and tonight I have a 16x16x16" box full of screws and bolts and nuts and assorted parts that need to go back in to finish my interior.