Peco equal length downpipes - any info? - Page 15 - Alfa Romeo Forum
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Originally Posted by Saabretooth View Post
http://uploads.tapatalk-cdn.com/2016...529f5bf107.jpg

Pud, is this a system you're now building for the 3.2 GTA?

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No, I'm not sure where the photo came from, I saved it on my PC years ago just for reference.

The size of the pipes in the photo is huge too, looks more suited to a race engine, maybe 3.7/3.8 than a normal GTA engine.
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Archimedes would have been proud Pud!!
Lol.

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Thats the thing, if the two downpipes were exactly the same length as each other then you would have a unequal length secondaries due to the different lengths after the collectors on the exhaust manifold on the CF2s, and due to the different position of the cats on the CF3s. Hopefully the difference in exhaust manifold length / cat position has been factored into the lengths of the downpipes so as purchased they would be unequal, but once fitted to the car they would give an equal length path for the exhaust gas to take.
mmmmm....seems my sports cat may not be the best choice then! It seems to me that you cannot win with CF3. On the OEM cat each burst/pocket of gas will emerge from the cat and have a different distance to travel. The front bank has further to travel to the back of the car and more importantly to the meet up point. I thought the point of EL (in terms of sound anyway) was to keep nice even gaps between each "ball" of gas. If they have to travel a different distance they inevitably collide. On my set up that will be as they enter the sports cat, on OEM it will be at the meet up point after the centre cat. Is this theory right?

What if you have a de-cat in the centre? Is your entire system effectively a secondary - manifold to back of the car?

I need to get my "trouble and strife" to sit in the car and rev it while I stand at the back because I've only heard from sitting inside. I want to make a video too at some point.
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mmmmm....seems my sports cat may not be the best choice then! It seems to me that you cannot win with CF3. On the OEM cat each burst/pocket of gas will emerge from the cat and have a different distance to travel. The front bank has further to travel to the back of the car and more importantly to the meet up point. I thought the point of EL (in terms of sound anyway) was to keep nice even gaps between each "ball" of gas. If they have to travel a different distance they inevitably collide. On my set up that will be as they enter the sports cat, on OEM it will be at the meet up point after the centre cat. Is this theory right?

What if you have a de-cat in the centre? Is your entire system effectively a secondary - manifold to back of the car?

I need to get my "trouble and strife" to sit in the car and rev it while I stand at the back because I've only heard from sitting inside. I want to make a video too at some point.
At low revs / low load you will get pretty much unrestricted flow through the cat, but as you get higher load and revs the flow will reduce and there will be a slight pressure increase before the cat, and a more steady stream of gas with less pressure pulses downstream of the cat. So where the theoretical "secondary" ends really depends on the load when you have CF3 staggered twincats.

I really wouldn't worry about it - the manifolds have unequal primaries anyway which means the exhaust system is not effectively pulse tuned. If you like the sound and can live with the ground clearance then you're onto a winner with your setup as it is.
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This is how my system looks. It is a 166 3.2 (so CF3 or actually CF4 as it had euro4 spec) with CF2 exhaust manifolds, custom made EL downpipes, and custom made cat section. Since I have rear exhaust manifold from 166, which isn't bend to the right (and it's shorter) as GTV CF2 rear manifold, so EL pipes cross differently (at least the guy making them said, he could not replicate alfatune EL design). Which means that oil filter is nearly impossible to change now ... but according to what is wirtten here in this thread this might be the most optimum design, when it comes to equal "lenghtening" everything Anyway here's the photo:
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At low revs / low load you will get pretty much unrestricted flow through the cat, but as you get higher load and revs the flow will reduce and there will be a slight pressure increase before the cat, and a more steady stream of gas with less pressure pulses downstream of the cat. So where the theoretical "secondary" ends really depends on the load when you have CF3 staggered twincats.

I really wouldn't worry about it - the manifolds have unequal primaries anyway which means the exhaust system is not effectively pulse tuned. If you like the sound and can live with the ground clearance then you're onto a winner with your setup as it is.
Thanks Dan - I was going to say one of the primaries looks twice as long as any of the others.
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This is how my system looks. It is a 166 3.2 (so CF3 or actually CF4 as it had euro4 spec) with CF2 exhaust manifolds, custom made EL downpipes, and custom made cat section. Since I have rear exhaust manifold from 166, which isn't bend to the right (and it's shorter) as GTV CF2 rear manifold, so EL pipes cross differently (at least the guy making them said, he could not replicate alfatune EL design). Which means that oil filter is nearly impossible to change now ... but according to what is wirtten here in this thread this might be the most optimum design, when it comes to equal "lenghtening" everything Anyway here's the photo:
Complicated stuff! I think as soon as you get CF2 manifolds on it's always going to be much easier to achieve equal everything.

Nice set up btw!
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Dan do my CF3 decat'd wizard manifolds make things better or worse? Are they just the same length as CF2's?

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Has anyone thought about having two separate set of pipes, cars, silencers etc for each bank right to the exhaust outlets

Except for sound, it would not matter if the pipes were of different lengths?

A mate of mine did this on his Triumph TR4 back in the 80's (shows age ) with each pipe set being fed by two cylinders!!! The manifold was actual two parts, which were then combined in the original exhaust pipes

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I was thinking about this Rich_wookey. It would be interesting to make an X pipe for more high end power and raspier sound, or making H pipe for more low end power and more "growly" sound. But I've never seen this being done on a busso V6 (maybe on some RWD models?).
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Dan do my CF3 decat'd wizard manifolds make things better or worse? Are they just the same length as CF2's?

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About the same length as CF2 primaries, not 100% equal but they are closer to being equal than the CF2s are, and oil filter access is better than factory rather than worse.
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About the same length as CF2 primaries, not 100% equal but they are closer to being equal than the CF2s are, and oil filter access is better than factory rather than worse.
Sounds good.

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See? I told you it was bloody complicated!!
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I've come to the conclusion that if it sounds great, then that's a result.

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Dan do my CF3 decat'd wizard manifolds make things better or worse? Are they just the same length as CF2's?

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You have de-cated CF3 manifolds? Did you gut them?
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You have de-cated CF3 manifolds? Did you gut them?
No they are wizard one's

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Finally bolted up, ground clearance is not as bad as expected.

Currently no gaskets, disintegrated on removal, so will not be able to hear/ drive with them until the new ones arrive in the post.

There was a mounting bracket for the original down pipes that needed removing on the ph1 v6 to get them to line-up without fouling anything.

The misunderstanding with the mechanic that failed to fit them initially came from
no gaskets available to him,
didn't want to remove the mounting bracket,
didnt like the the difference in internal diameter/bore between the manifold/ELDP
(where the 3 branches become one) is a much larger diameter before passing into the narrower down pipe, he felt this was restrictive even if that is the OEM design.
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'98 916C1 GTV V6 24V - Rosso 130 - 885 Tan Momo - 321 Wood pack - 17" Tele - Zender 'cup' Aero - BMC CDA - Wizard Quad - ELDP - Over racing Ti strut brace - Intrax RS coil-over
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Brilliant info and pic mate, cheers for the update.

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All the people in this thread who promised to post videos once their ELDPs were installed have not.
Please do. I'd really like to hear them. I am sure others would as well. Thank you.
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As before I seem to be restricted to one photo per post on ipad, didn't intend for it to go sideways/landscape either.
Hi James could you do a quick pic of the clearence under car, with the car on the road. Like uncle's 'scary' photo lol.

How are you finding the sound now? And day to day living with the clearence?

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I tried to but my wife who was holding the video phone was SLOW DOWN SLOW DOWN, i will upload one when i can

its insane though i tell you just simply amazing sound
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All the people in this thread who promised to post videos once their ELDPs were installed have not.
Please do. I'd really like to hear them. I am sure others would as well. Thank you.
I would say that this 3.2 GTV with EL downpipes (and CF2 manifolds with sport silencers), is one of te best representations of what EL downpipes actually do to the sound - basically it gives it that race-bred sound at higher revs - absolutely wonderful and similar to RWD V6 alfas of the past, although still different to 12V engines. Enjoy:


And this is 164 with EL downpipes, its insanely good:
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Last edited by lizard; 18-08-16 at 16:12.
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All the people in this thread who promised to post videos once their ELDPs were installed have not.
Please do. I'd really like to hear them. I am sure others would as well. Thank you.
I did it dude!
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ordinary driving just how it is ALL the time in urban areas through the gears
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https://www.youtube.com/watch?v=LC7RprMupEI

ordinary driving just how it is ALL the time in urban areas through the gears
Ah Himley! always a good straight line blast up to the island at penn and back..

Sounds good although I know it will sound 10 times better in person an 20 times better from the outside.
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