Free flow muffler = fuel mixture errors?

[metroschultz]

Originally Posted by Chris D.

You can get stainless flex pipes for far cheaper on ebay..

I thought $26 to my door was pretty cheap as it is.
If i can get it for less I'm always willing to save money.
I'll go look now.
Thanx.
S.

[roflwaffle]

Originally Posted by metroschultz

I know VW has the exhaust come out the back and down the firewall then to a ball coupler then to the rest of the system. maybe if you added a flex in the system just after the ball socket? Hmm? Maybe?

The toilet ball exhaust is usually fine in terms of keeping everything uncracked, but what happens is that people would put a 4 into 2 exhaust from a gas rabbit, since is supposedly flowed better, w/o mounting it to the chassis or using a flex pipe, both of which were things it came from the factory with, so either it or the exhaust would crack.

[roflwaffle]

VW fixed mine in 81. I wanna fiddle with the timing advance and governor so I figure I might as well replace all the seals and I have a spare pump anyway.

[SL8Brick]

Bruce,
If your goal is clean up the aero profile of the exh system, why not just go with the IPD turbo exhaust kit(or DIY w/FCP exh components)? You'd get rid of the resonator and gain some pipe diameter, all the while staying with OE components. And if you wanted to get even more efficient, you could replace the round OE turbo muffler w/ a strait-through bullet-style muffler. A small diameter bullet muffler could easily be tucked up inside the muffler well behind the rear bumper and covered w/ a louvered undertray.

[roflwaffle]

Originally Posted by diesel_john

Mine doesn't have a governor, the industrial model for fork lifts had a governor.

What? That's unpossible! If it didn't have a governor you would floor it and it'd run away until it died.

[roflwaffle]

Ah yeah, the intermediate spring. If you take that off an engine should stay at whatever high idle the governor is set to.

[trebuchet03]

Originally Posted by Frank Lee

The point was there is lots of latitude for what will work to make a functional exhaust system. Trying to dissuade/scare someone off by talking about nodes and s*** is, well, B.S.

Sorry for the late reply..... But I agree - there's plenty of room to make a working exhaust system.... Auto mfr's just optimize as efficiently as possible as it's a big difference for them. Telling the muffler shop to move a hanger over a couple inches isn't going to change the cost of a custom job. The muffler shop also won't be optimized like the mfr who optimizes for more than power and torque (two things a corner shop guy is likely more concerned with)

And that said... I didn't see any dissuade anything over nodes/anti-nodes. I mean, really, look back... The last sentence of john's post was something like "Will it matter.... no" And really, nodes aren't scary - it's a relatively simple concept to grasp and is fundamental to a great deal of design for intended for public use The scary part is anti-nodes - that's where things can fail horridly :/

[roflwaffle]

Originally Posted by diesel_john

is there a way to make mine a constant speed control using the go pedal for the setpoint, so it would not just be limiting the spill rack but increasing fuel if the rpm dropped below the setpoint.

is it the governor spring in this picture

No, with just adjustments/tweaks. Maybe, if you have some technical/electrical know-how...

-No. The only things you can adjust are how much fuel is injected at WOP (wide open pedal) via the Full-load adjusting screw, at what engine speed fuel starts getting cut via shimming/changing the Governor spring, and how fast it drops back down to low idle via removing/replacing/changing the Intermediate spring. So, you can adjust how quick it revs, how much fuel is injected per firing, and when the fuel gets cut/peak power/engine speed, but I don't see how you can set it up so that it'll increase fueling when engine speed automatically drops as dictated by a setpoint via the engine speed control lever/pedal.

-Maybe. If you have something that can move the Full-load screw in and out while driving, and a speed sensor, I think it's possible to build a circuit that will move the Full-load screw in and out in order to keep everything at a set speed. Whether or not this is easier/cheaper than a cruise control setup that just moves the pedal cable according to some speed sensor, I'm not sure.

[presidential]

Originally Posted by fanamingo

Some of us are pretty new to modding in general. Do you have some good tuning resources you could link to for us? My limited searching has turned up a lot of results that haven't been very helpful.

I'll leaf through my bookmarks and see what I can do. Most of what I know started before there was an internet...

[aerohead]

Originally Posted by brucepick

OK, I'll try to keep the background writing brief.

I asked my mechanic friend if he'd install a smaller muffler in a different location, to enable me to do a better job covering the underside for aero improvement. The OEM muffler sits behind/above the rear bumper and I'd like to relocate a smaller muffler over on the side instead.

He says that the only muffler one could find that would fit would be a "performance" fart can. And that the reduced backpressure would fool the fuel management system into messing up the mixture which would defeat my purpose.

My '89 Volvo uses a Bosch Air Mass Meter between the airbox and throttle body, and an oxy sensor located in the cat converter.

He's basing his judgment partially on his own experience in his '85 Volvo that's turbo'd and has significant performance mods on top of that. When he opened up the exhaust system he had to remap his fuel management system. Both of us have 2.3 liter engines, his is turbo and has a mechanical air flow meter vs. my amm. My exhaust is 2" piping + cat + resonator + muffler. His is 3" piping plus cat + 3" exhaust pipe. No muffler.

What do you guys say? Should I go ahead and ask him to do it anyway? Or hunt for a restrictive fart can or add restriction to typical one?

If changing the muffler is going to open a bigger can of worms,I had a thought you might consider.Adding a undertray/bellypan only works if it is continuous to the front of the car,or the carmaker has already done such a good job at the vehicle's front,that it can provide attached flow to any additional underbody structure you might add.If you can get the belly of the Volvo clean,up to within striking range of the muffler,you probably won't miss the difference at the gas pump for not having the last and final section.The flow WILL separate a little early,but it will basically have all the useable kinetic energy of a fully paneled car.A fairing could also be attached to the muffler itself.I had to do this on the CRX.Subaru did alot of research with this sort of thing in the Eighties on their XT sports car,and found that bits and pieces of paneling perform close to that of a perfect pan as long as flow is clean in the forebody.You've got to respect heat buildup,however heat-blocking wraps,as used on racing headers,could get you around that one.It would be a real service to mankind,if all mufflers were rated for pressure differential at a uniform flow rate.There'd be no need for guessing about swaps.Perhaps SEMA will wake up one day,and get their members to provide potential customers with useful flowbench criteria for which to select aftermarket equipment.