Last time, at the SPRT Skunkworks:



I tried the rosebud tip on the torch to heat both tubes up bright orange and bend the header all at once. After much fighting (2 feet of .125 wall pipe takes a lot of time to get hot enough to STAY hot!) I was able to get the 6' prybar in there against the transmission... and I bent it OVER, but it was still off-angle on three axes.

Crap.

So much for Plan B, let's go back to Plan A:



This is the same tube that I'd previously cut off to convert this 12A header to a 13B header. (The difference is the 13B is 10mm longer across the ports) The angles required meant that this tube needed to be shorter, but not MUCH shorter, so I killed a couple Sawzall blades by chewing through the nice pretty weld bead against the flange. The leftover tube in the flange was held in by a couple spots and popped out easily with a chisel.



This is the result of much heating, bending thisaway with a prybar inside the tube, heating a different area, twisting thataway with giant channel-locks, heating another area, jacking the header up with a pole jack (needed to counteract the "thisaway" bend), which got me CLOSE. Then some long 3/8" bolts got started in the flange, the whole tube was heated orange, the bolts got snugged, tube heated some more, bolts snugged some more... When the flanges finally mated, I let it cool off, then heated the whole thing up bright orange again, figuring if there were any residual stresses, this would make them go away.

I must have been right, the flanges stayed true to each other after I unbolted it all.



The #2 tube needed to have the final bend straightened out to make the angle fit better, and a maybe 3 degree bend put in halfway up the tube, but it fits now!

At this point, I'd been working on the exhaust system for six hours and it was time to go home, so I welded the bottom half of the tube to the flange and called it a day. Next time, the header gets removed from the car entirely and the weld finished up.

THEN I can drive it to see if this exhaust is a power improvement or detriment, so I can see in which direction I need to go when porting my next engine.

 

thats a lotta work!

 

Rotary Engineering header to RB center section = success!

 

A who now?

 

The header pictured above is a rotary engineering header. It explains the slotted stud holes where RB is round. Next the two piece flange where RB is a single piece with "RB" cut out. Third is your dual pipe flange down where it meets the center section. A) You should not have to bend anything to make an RB header fit and B) the flange looks like RE, not RB and C) the holes are offset looking in the pic.

Then again I'm not there to look at it in real life, but from the RE headers I've seen (and recently aquired) your header is RE, not RB.

 

backpressure number?

 

you shouldnt jack the car from the tranny but good job on the pipe

 

??? The pole jack is about 3" below the trans, it was being used to bend the header up. I realize that the bright yellow lift arms are probably hard to see, what with being bright yellow against brown and black...

Anyway - Thanks Jeff. I bought the header used from someone and we both thought it was RB.

RB and apparently RE both have offset bolt holes at the header outlet flange, the difference seems to be that the flange is reversed. So I was figuring that the header was one of those weld from a pile of tubes and flanges deals. It's no biggie, the whole exhaust system ran me something like $300 so I can't complain!

I did have to do a lot of hacking to the engine flange in order to get it on and off without having to remove the motor mount. And it's always 1/8" not enough material

I'll know a backpressure number possibly by the end of the month. Goal is less than 4psi. Actually what I am going to do is a poor man's metric - I'm going to datalog a couple full-throttle passes and see where the air/fuel ratio is. If it's leaner, I improved airflow, if it's richer, I made it worse. I *think* I tuned the engine to about 12.0-12.5:1, will have to check last year's datalogs to be sure.

I'll just have to be careful, as I had to cut my Panhard off in order to make the HUGE rear muffler fit, and the Watts pivot is only tack-welded in place, since it had to be cut off of this housing to repair the cracks. New rearend goes in soon, and from the size of the muffler, it looks like I'm going to have to keep using a Watts instead of the panhard. Panhard rod handles SO much nicer.

 

What's tinsel strength?

 

i know you made your own, but the Gforce panhard fits with the RB streetport system, so its possible.

plan B might be to make the watts from rod ends, i built one, but haven't tested it yet, it seems to fix the binding, as it allows the watts link pivot to move thru its gyrations.

 

Binding is not a problem, the problem is the geometry sucks. Roll steer goes up dramatically with the Watts compared to the Panhard because of the interrelation with the links, and the roll center? Jeez! Before I did all of the suspension conversion, I had a "moment" on the street where it felt like what I assume swing axle jacking feels like. The back end rose up a bit, the inside rear tire lifted off of the ground, and rear axle steer went from one direction to the other. It didn't slide when it did this. I figure only the puckering of the driver's sphincter pulled the car back down That was the point that I said the Watts needed to die.

And the roll center discrepancy will be even more sucks with the FC front end's lower roll center. I may be able to counteract it somewhat with more ride height in the front, but all the same...

I haven't had much time to look at the car and see where to fit a Panhard. I remember seeing the G-Force design and not liking it, but I forget why. One issue is that the down-bar will have to sit a lot more forward, meaning the axle end will have to be sitting way out on a stick, and I don't like the leveraging effect that may cause. I frequently slam sideways into ruts hard enough to bounce the car off the ground, I don't want to have to worry about the suspension failing. I did that once already, it's slow and smells bad when the inner fenders are used for axle location

 

lmao! i can't believe i forgot about the roll center, of course you're right! i actually had a moment in peepers too, it felt like one of the bolts fell out of the bottom of the strut, but just for a second.

turn 15 is the only one with a wall too, so pucker factor high!

change of underpants, and nut and bolt check reveals that, i think i hit a bump, so its peepers 2 drivers 0, the car is intimidating because you think its gonna do something scary, but it doesnt!

the gforce mount on my old car was pretty sketchy, it was like a 1x1 tube bolted to the chassis, it was the source of some of the clunking!

 

The level of brightness of a Christmas tree.

 

Oh. Wow.

Idle speed has not changed (half bridge early-style engine with the rotor housings relieved to within 1mm of the coolant seal, so it's very sensitive to backpressure) and the car seems to pull okay in the midrange and it has a phenomenal 6000-8000rpm RUSH, especially after a shift (3rd pulls as hard as 2nd now??) so I really need to get the 2mm seal engine put together so I don't have to cut the fun off early, BUT.

The car is QUIET now. Like, it's quieter than my VW. I can't hear the exhaust anymore unless I'm over half throttle.

Did I mention that the old exhaust had the engine going "soft" over 7500? Now it slams into the rev limiter like it insulted its mother.

Hey Mikey, I think he likes it.

This weekend will bring the datalog testing.