Another exhaust question: flange size/downpipe/DIY?

[Airwick]

I am looking at replacing my dying exhaust with a 2.25/2.5 side dump system and I have a couple questions.

The main one is what are my options regarding the flange connection? The last place I went to want to do the standard "Keep a couple inches of the existing pipe after the flange and weld from there.
- My question is how big is the actual hole before the flange (in the cast downpipe); is it any bigger than the stock exhaust (that would seem strange as it would mean the stock system actually goes down in size at the flange, but you never know)? If it isn't any bigger then it would seem the loss with keeping a few inches of the stock pipe should be minimal. If it is bigger, you would really want to try to get rid of as much of that restriction as possible, which brings me to the next question.
- If the muffler place isn't willing/can't find a new flange and I want to make one, is there any way I can come up with one myself and what would be involved (i.e. what does it look like?) also I read a SS one is hard to find but what about a regular steel one?
- Last question, has anyone gone through the trouble of actually replacing the whole downpipe with something bigger? By that I mean from right after the turbo. The cast piece that flange mounts to is bolted onto the turbo so if you got rid of that and connected right there, wouldn't you gain more?

Still considering my options here because if it's just going to start after the flange; I can probably go Canadian tire and buy a cherry can and some pieces of pipe, elbows and reducer, clamps etc and slap something together in a couple hours for a lot less than $375 (quoted price for install with Magnaflow 2.25") and no special tools.
It might not be as nice or last as long but it should work just as well...

Any thoughts?

[jessef]

After having four L300's done all at different shops, I've come to the conclusion that 2 1/4" is the max width at the flange base in between the two springs for a pipe to be welded on.

2.5" rubs against the springs at times.

I also found no difference between 2.25 and 2.5" exhausts with the same muffler. That's straight 2.25" from the flange back and stock pipe 6" at the flange and then 2.5" pipe welded to the stock.

I don't like the idea of leaving under 2" pipe after the flange and then 2.5" welded on. Seems like a bottleneck.

[Airwick]

Thanks for the info.
I agree that I don't like having that short piece of smaller pipe as it seems like a bottleneck (but only if it's actually smaller than the hole coming out of the downpipe, if it's only a couple more inches of the same diameter it's not actually a restriction)...

There is one thing I am not quite clear about though: when you say "straight 2.25" from the flange back" how is that done exactly? Do you take the plate (the one the springs push on) and weld the 2.25" pipe straight onto that? Or is there some other subtelty I am not getting?
Are there any issues with leaking there if you do it like this as the stock system seems to have a bit of a swivel in there or something (stock pipe isn't perpendicular to that flange when I look under my van)?

I'd love to see a closeup pic of what that looks like on yours...

Is it easy to remove these 2 rusty nuts/springs to have a look at the downpipe diameter (I haven't dared to touch it yet in case they are seized and I break something...)


Thanks

[thelazybrownfox]

Airwick
The whole exhaust manifold/turbo piping arrangement is supposed to be able to move with the heat buildup. Apparently the expansion is incredible, to the point of breaking exhaust bolts if everything is to tight. IMHO those springs might be part of the movement needed. Removing the spring might not be a good idea. I like your ideas though.
TLBF

[Airwick]

Well, I don't know for sure if I have it right... that's why I am asking.

I wan't thinking of getting rid of the springs though... Just letting the plate that is pushed by the springs come in contact with the flange on the downpipe. The issue I see with that is that everything would have to be aligned pretty well so that one sides wasn't pulled away as that could cause a leak.

I'm still not clear as to how the systems that completely eliminate the original pipe connect to the downpipe...

I hope someone is able to get it through my thick skull

[fexlboi]

If the muffler place isn't willing/can't find a new flange and I want to make one, is there any way I can come up with one myself and what would be involved (i.e. what does it look like?) also I read a SS one is hard to find but what about a regular steel one?

I know you are on the island, but it's maybe worth a trip to http://www.muffler-tech.com They are the only muffler shop I have found which has the right SS flange for a Delica. Also they do mandrel bending to avoid any bottlenecks at the bends. Nice people, quality work and worth every penny.

Last question, has anyone gone through the trouble of actually replacing the whole downpipe with something bigger? By that I mean from right after the turbo. The cast piece that flange mounts to is bolted onto the turbo so if you got rid of that and connected right there, wouldn't you gain more?

You wont find any larger diameter down pipes, but if you a willing to spend extra cash, this shop does custom down pipes as well. (Probably not worth the money)

I can probably go Canadian tire and buy a cherry can and some pieces of pipe, elbows and reducer, clamps etc and slap something together in a couple hours for a lot less than $375 (quoted price for install with Magnaflow 2.25") and no special tools.

Well you can do that too if you want to cheap out.

I wan't thinking of getting rid of the springs though... Just letting the plate that is pushed by the springs come in contact with the flange on the downpipe. The issue I see with that is that everything would have to be aligned pretty well so that one sides wasn't pulled away as that could cause a leak.

Be careful with this. There is a reason for the rubber hangers and springs on the flange. The exhaust need to move so it won't cracking the down pipe/headers.

[jessef]

weld 2 1/4" pipe to the flange and whatever you need from there back.

[FalcoColumbarius]

weld 2 1/4" pipe to the flange and whatever you need from there back.

Are you serious? Doesn't the assembly need a stress relief?

[Jsq]

My exhaust is very happy on the prairies...no salt or rust! Since I don't need stainless I got our local muffler/exhaust expert to custom fit a side exit 2.5" pipe with a 12" long straight thru glass pak. Took him one hour and the total bill, material and labour, was $127. (Wonder how he feeds his kids? Labour was $28.)

My delitune is now similar to a Kubota on steroids. Not too loud but at least it sounds like a diesel!

[Airwick]

Thanks for all the input.
I will go with what the shop proposed: 2.25" exhaust and Magnaflow muffler, keep a short piece (only about 2-4") of exiting pipe after the flange to make easier to assemble and keep the adjustability/tolerance to mis-alignment.

This will get done next Thursday.

Next step: install EGT gage, then check/adjust boost

[jwfchase]

That's exactly what I had done, but w/ 2.5" pipe from the muffler to the side exit. I had them poke the side exit out a bit so I wouldn't end up with any soot on the side of the van or tire.

[jessef]

weld 2 1/4" pipe to the flange and whatever you need from there back.

Are you serious? Doesn't the assembly need a stress relief?

that's what the springs on either side of flange/pipe are for

If you ask Joe (luna sea), he'll kindly snap a shot under Turtle of how it was properly done (2.25" pipe flush up to the outlet at the flange = no bottleneck restriction)

Below is what the first 2 muffler shops did to my exhaust. Instead of taking their time to mate the 2.25" pipe right at the flange bracket, they just cut 4-6" down and weld the new pipe onto the old. It's a quick and easy way to do it, but it stills leaves that bottleneck (large - small - large).

A good muffler shop will not use the old pipe. They will remove the flange bracket and weld the new larger pipe to it, then install it. It takes more time and skill, but obviously worth it.

[FalcoColumbarius]

Ah, the way I read it I thought you meant welding the pipe right onto the flange, of the exhaust manifold. Thank you for clearing that up for me.

Falco.

[fexlboi]

That's how a properly done flange should look like if you find a shop who is willing to do it right (and not charge a fortune).

[jessef]

That's how a properly done flange should look like if you find a shop who is willing to do it right (and not charge a fortune).

The man is correct.