Snorkel Diameter/Airflow How big does it need to be??

[leehamescort]

G'day all.

I currently have a standard type plastic snorkel on my surf running a 308 V8 with a 470CFM Holley Truck Avanger (vacuum secondaries). I've been told by the Dyno tuner that i need a bigger snorkel as the vacuum caused by the snorkel is playing havoc on the carby.

I'm running a standard holden 308 aircleaner with a flexi hose from the snorkel to the intake on the aircleaner snout.

I'm not a fan of putting a massive 4" snorkel on the car so though i would put two 2" snorkels. A quick bit of the old maths on the calculator and i worked out that 2 x 2" snorkels only gives me half the area of a 4"!!

How big do i really need the snorkel to be?

Thanks for any help.

Leeham

[GUEEY]

I had twin 3 inch ( Black ) snorkels on my 350 Chev FJ40, feeding a Q-jet.
It run fine on the dyno and on road.
I was told by my tuner than twin 3 inch was the required airfow.
fitted to a large diameter airbox.

Grant.

[Struth]

Mines 3" on the 5.0 and the dynotuner told me that he reckoned it was too restrictive as well.

I don't like the idea of a 4" snorkel either but reckon it will look better than twin 2" or twin 3"

What size is the inlet on the 308 air cleaner, could probably do with a custom air cleaner can with bigger inlet as well.


You are right though

2 x 2" snorkel will give you6.3" of tube area,
1 x 3" will give you 7.1" of area,
1 x 4" will give you 12.5" of area,

They are big differences and 1 x 3" will be more effective than 2 x 2".

Poor air flow will also destroy your fuel economy so the right size snorkel will help extend your range.

I have the parts to go single 4" on mine ATM so let me know if you are intersted in a single 3" jobby.

Cheers


Cheers

[Dzltec]

Your tuner should be able to measure how much of a restriction it is. If he can't or doesn't want to, find someone else. What is so wrong with a good fabbed 4" snorkel?


Andy

[Struth]

Your tuner should be able to measure how much of a restriction it is. If he can't or doesn't want to, find someone else. What is so wrong with a good fabbed 4" snorkel?


Andy

They are pretty big when bolted to a Surf, but I reckon they are the best option for good airflow.

Cheers

[Kitika]

I reckon my 4inch snorkel looks small on my 80series and would prefer a 5inch. I got a snorkel head from a truck spares shop for $60 to suit the 4inch pipe and the mouth of it easily swallows a standard safari type 3 inch head
Will the 4inch flow enough air for say a 350/Ls1 V8? As that's what i'm putting in at the moment.

[vanbox]

Is there an equation for working out airflow?

got this of donaldson website. can anyone confirm?

http://www.donaldson.com/en/catalogs/engine/033609.pdf

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