Peco equal length downpipes - any info? - Page 14 - Alfa Romeo Forum
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Cheers James thanks for the photos, saved all three! That baby looks like it will be loud! Are the manifolds de-cat'd as well?

The CF3 design looks so different to the CF2 one and I can't work put why as I thought only holes in the flanges where different. Maybe someone else knows why.

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Worst clearence than uncle's?http://uploads.tapatalk-cdn.com/2016...f01cfc7c1d.jpg

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Here's the CF2s again for comparison.http://uploads.tapatalk-cdn.com/2016...bdbf9a30f5.jpghttp://uploads.tapatalk-cdn.com/2016...6d3f95bd44.jpg

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Have any of you guys a actually measured the pipes to see how equal length they are?

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Cheers James thanks for the photos, saved all three! That baby looks like it will be loud! Are the manifolds de-cat'd as well?

The CF3 design looks so different to the CF2 one and I can't work put why as I thought only holes in the flanges
where different. Maybe someone else knows why.

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It's a bit louder than before which I'm happy with! Unfortunately I still have the evil pre-cats. When I can find several excuses to take the engine out I'll get them off, but it's a long way off.

I am revising my estimate to 40mm to 50mm below the sump just so I don't give anyone false hopes and they go and buy some! I will try and measure properly some time.
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Worst clearence than uncle's?http://uploads.tapatalk-cdn.com/2016...f01cfc7c1d.jpg

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Mine's not as low as that. I think he had some suspension sag issues.
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Mine's not as low as that. I think he had some suspension sag issues.
Phew.

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It's a bit louder than before which I'm happy with! Unfortunately I still have the evil pre-cats. When I can find several excuses to take the engine out I'll get them off, but it's a long way off.

I am revising my estimate to 40mm to 50mm below the sump just so I don't give anyone false hopes and they go and buy some! I will try and measure properly some time.
Have you got lowered springs? Or is it standard and fresh? Just trying to get an idea of best case senario.

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Have you got lowered springs? Or is it standard and fresh? Just trying to get an idea of best case senario.

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Standard and completely rebuilt this year so no sag. I'll try and get a front on photo for you tomorrow.
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Awesome. I'm thinking of doing a front end suspension rebuild before fitting the eq pipes. Which shocks do you have, standard?

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Suspension sag

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Originally Posted by james2375 View Post
Mine's not as low as that. I think he had some suspension sag issues.
Hi chaps, sorry been AWOL for a while - too much going on
Anyway - yes I had suspension sag - evident by the excessive negative rear camber but the good news is that the car is on the ramps on Wednesday having new suspension fitted, springs, shocks and an alignment done.

As this is on the rear only, I'm not expecting a great improvement in ground clearance but it may give me 5-10mm I guess?
Every little helps (as Tesco bleat on) and God knows I need it - I have scraped the lowest pipe several times now on fast dips, speed bumps and even when pulling out onto a road from a slight incline.
Also my EL's are now rattling like a bugger on the overrun and in reverse gear! Anyone else had this issue?

Other than that, the sound is totally epic although I'm buying a "Decibel Devil" to bolt on for a track day soon.

2002 Spider V6 24v
EL downpipes, Ragazzon exhaust
BIG noise!
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Awesome. I'm thinking of doing a front end suspension rebuild before fitting the eq pipes. Which shocks do you have, standard?

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Suplex springs and TSW shocks for me from Alfashop, along with new Goodyear Eagle F1's all round..
Front end will have to wait until after my Summer holiday!!
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Have any of you guys a actually measured the pipes to see how equal length they are?

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I'm not quite sure what is meant to be equal about the downpipes as far as the design goes. Is each downpipe equal in length? Or does it mean that when a car is fitted with the equal length downpipes that the 'secondary' from each bank of the engine is equal?

A rear CF2 manifold has about 3" of secondary after the collector before the downpipe is bolted on, the front manifold has the flange immediately after the collector, is that taken into account in the design?

CF3 centre cats are staggered, the cat for the rear bank is further back than the cat for the front bank, is this taken into account in the design? If it is, does that mean when you fit a single sports cat to the centre you are effectively making your secondaries more unequal?

When we did CF2 manifold conversion downpipes for the 156 & 147 GTAs we measured up and found we were within 10% of being equal when the centre cats and the rear manifold's extra 3" is taken into account, and that was following the straightest smoothest route.

These downpipes are all certainly longer than the originals, and lengthening the secondaries will alter the engine's torque curve and sound properties without a doubt.

Other things to bear in mind:

- the primaries are not equal length
- If you were going for a tuned length exhaust system, longer primaries would be the goal to increase power & torque, but they would be seriously awkward to build & fit.
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These downpipes are all certainly longer than the originals, and lengthening the secondaries will alter the engine's torque curve and sound properties without a doubt.
Can you maybe explain in what way torque curve changes?
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Generally having longer secondaries on a system with already very short primaries will likely mean more torque at lower revs and less torque at higher revs, but you wouldn't be able to say for sure where the torque starts to drop off unless you put it on a rolling road. The diameter of each part in the system comes into play too.
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So really the rear bank down pipe could do with being 3" longer than the front, then use a sports cat.

Although it's the sound I'm after really 😃

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Confused?
Moi??
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Confused?
Moi??
To make the pipe equal from port to tip.

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To make the pipe equal from port to tip.

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Yes thanks - I understood that bit!!
It's just the numerous combinations of possible effects that are confusing.
I ordered my EL's in the hope that the company making them had worked out the measurements involved and manufactured accordingly, otherwise, I'll sue them for using the phrase "Equal length" - it's a Trade Description misdemeanor!!
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Lol. Ok, we could clump together and make it a class action class, or is that just an American thing 😜

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Yes thanks - I understood that bit!!
It's just the numerous combinations of possible effects that are confusing.
I ordered my EL's in the hope that the company making them had worked out the measurements involved and manufactured accordingly, otherwise, I'll sue them for using the phrase "Equal length" - it's a Trade Description misdemeanor!!
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.

You can silicone a metal plate to the bottom flange of each downpipe and then fill up the downpipe with water from the top, measure how much water it takes to fully fill each downpipe and then you will have an idea of how equal they are.
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Radical. Down pipes by displacement lol.

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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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Radical. Down pipes by displacement lol.

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Archimedes would have been proud Pud!!
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