PatAllen

myth buster: exhaust manifolds...

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since i have a flow bench, and tons of various manifolds, i decided to test some of them.

My test consist of placing the manifold over the bench and make it suck air from it, to measure global resistance. My flow bench is not very accurate with open pieces like that, but it shows any variation possible. A toothpick placed over the port can show a difference in the readout.

I never totaly bought the idea that a Tii manifold was "that much" a wow item.

I tested 3

a Tii one, without any smog port drilled out (no egr or injeciton tubes), removed from a Tii engine

a very early type with only the egr port (blocked off)(from a 121Ti head type with very low vin)

a smog one with egr and injection port, but the injection tubes removed, from a late 75', the ports looks like much opened up that the 3 others, with no "bumps" in the ports for the studs (which would mean more flow essentialy)

Results ??

the one with the injeciton tubes removed flows more than the Tii piece, and the old one with the egr port blocked-off flow exactly the same as the Tii one....

121Ti: 253.40

smog:254.70

Tii: 253.40

note that thoses numbers are just "units of flow" because my FB is not calibrated over 240cfm.

Do your own conclusions. I did mine.

Is there specific part numbers for the Tii manifold ?

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hey pat,

u don't have a non-tii manifold to test do u? i'm assuming no since that was not tested. i would love to see results for that as well.

edited: is the smog manifold a non-tii one?

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yes, read carefully, i tested 3

1 (one) Tii

2 non-Tii, one from a old 121type motor (1969 iirc) and one from a 75 full smog spec.

yes the smog one is non-tii, there was NO smog equipment at all on the Tii (no egr of air pumps)

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Hey Pat, did you try flowing each port( runner) separately?

I too had noticed that, while the tii port is wider in section,

the ports on the air injection version seemed to be pretty similar

in diameter. Never bothered to mold them, tho...

Nice.

t

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Hey Pat, did you try flowing each port( runner) separately?

I too had noticed that, while the tii port is wider in section,

the ports on the air injection version seemed to be pretty similar

in diameter. Never bothered to mold them, tho...

Nice.

t

its on my to do list to flow each port individualy.

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All great info Pat.

What about any shape differences of the ports? Exhaust is hot and it expands.

John

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All great info Pat.

What about any shape differences of the ports? Exhaust is hot and it expands.

John

they show all exact same flow path and shape, the only visible difference is the smog one with the air injections tubes, it doesnt have the bumps near the studs at the inlet of the ports that would logicaly impede flow performance, the end result proves my theory there. i guess with the tubes the engineer found out that the manifold was too much restrictive so they made the casting a little bit larger to compensate. so with the tubes removed it flows very well.

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Cool info.

Wasn't Metric Mechanic a fan of ported stock manifolds?

John

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Cool info.

Wasn't Metric Mechanic a fan of ported stock manifolds?

John

yes they did. they opened them up pretty mad. much larger than the head, to use their patented anti-reversionnal effect.

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nice info. Thanks!

Now I just need some caps to plug the smog ports on my CA smog manifold.

:-)

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Guest Anonymous

it would be nice to see how the 02again and IE shorty manifolds flow

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Nice, I can already see the Tii manifolds coming down in price lol. Not that I know, but are they typically more expensive?

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is there any other exhaust type anyway? (apart from the smog ones)

When i look through the online ETK i get only one part number for every car from 2000-2002tii - does this mean they had all the same headers or does it mean they only sell one now but had different ones back then?

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Pat, with the large store of manifolds you have, do you know, or does anyone know, if the air nozzles in the CA smogger are threaded or pressed in?

There is a flat side on it that suggests it was threaded in.

I was wondering if it's feasible to remove it. But I don't want to snap it off, yet.

Thanks.

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