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Spyderman · Alfasud Joined: 04 Sep 2003 Posts: 48 Location: Hampshire

Heres a question
These hard to get hold of Cross over exhausts, think Ansa used to do them.

Are they worth while, in terms of a power mod.

If so what sort of power increase would they be worth if fitted to a 1.7 16v
I know i would have to get one custom made , but as it would be going in my kit car it will be custom made anyway.

Toad · Alfasud Joined: 19 Mar 2003 Posts: 42

145/146 Boxer's had a crossover exhaust.. If that's any help to you
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James Granger · Alfa 33 Joined: 10 Apr 2003 Posts: 302

I've heard that the original exhaust system was as good as any cross-over performance mod. They are apparently a waste of money - might sound nice though!

tvatavuk

mannit · Guest

Hi,

My 1993 16v has a crossover as standard which apparently is to reduce the manifold length to fit in the cat, but I think it is to give a power gain to try and make up for the cat!

Had a full Ansa system including crossover manifold on an Alfasud 14 years ago which was fantastic. It used to go bannanas over 4500rpm. The only problem was the ground clearance. On the 33 though the manifold bends round the sump so not a problem

John

Buck Bundy · Alfasud Joined: 30 Oct 2003 Posts: 68 Location: Anglesey

I had a full Ansa system put on my first Sprint. The guy who fitted it reckoned it was good for an extra 8bhp on an otherwise standard 105bhp engine.

Whether it was or not I'd never be able to tell because when I gave him the car it was badly set up, but when I got it back it was superb. The crossover pipes got a good few dents put in them but were pretty tough.

The sound was superb, but I guess you could have achieved the same from just the Ansa back box.

The Sprint I have just bought is also fitted with a crossover manifold, but it isn't nearly as low as the Ansa, a compromise, perhaps? Unfortunately it has been fitted with a 'Kwik fit' type of system behind it, which will have to be replaced.

Buck
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Peter D · Alfasud Joined: 15 Aug 2003 Posts: 60 Location: Denmark

The original 16V cross-over manifold found on some cars are not the real thing, because the lenght of each pipe before gathering together is not the same.

The cross-over manifold gives a better, more even flow, due to the ignition sequence (two cylinders in the right side fire after each other, and then two cylinder in the left side of the engine fire after each other). But the lenght of the individual pipes should also be the same.

I have not made tests on the 16V engine, but in the old days we made a lot of tests, and the cross-over manifold gave about 5 bhp extra, and in the whole rpm-range, not just at the top.

The extra bhp was less on a standard 1.2 (maybe 2 bhp), but the gain increased with the capacity and tuning grade, so that on a 1.5 tuned to about 110 bhp, the gain was about 6 bhp.

Peter (DK)

Eddie W · Posted: Tue Dec 09, 2003 9:56 pm Post subject:

Does anybody have pipe dia. and length figures for these exhausts. presumably the dia is different for a 1500 as against a 1700.
Regards Eddie
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RpmHead · Posted: Wed Dec 10, 2003 3:02 pm Post subject: Re: Cross-over manifold

Peter D · Alfasud Joined: 15 Aug 2003 Posts: 60 Location: Denmark

Hi Stian

Thank you. Iresa obviously still exists. Then I will contact them.

On their website I cannot find the informations that you found about partnumber and price. How did you find it?

I do not have experiences in the form, how much more power does the Iresa manifold give on a 16V boxer (only the old experiments that I told about).

I had the manifold on my 1.7 16V racecar (now sold), and I still have it on my 1.5 8V supercharged trackday car. But most of the changes were made at one time, so you cannot single out how much each change contributes.

I now (after 15 year of use without problems) want to change my 1.5 8V supercharged engine to a factory new 1.7 16V with the same supercharger, and then I need the cross-over manifold for the 16V.

Peter (DK)

RpmHead