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need help with snorkel size on GQ with 454

Posted: Tue Oct 25, 2011 9:02 am
by ANDREWGQ 351
Hi all,
My 1990 GQ has a 454 vortec motor with twin 425 impco gas mixers. The current setup has the 2 mixers on their side each with 4" tubing blending together onto the top of the inlet manifold with one 850 DP holley base plate. Then there is an exposed oval filter on the mixers.

I want to add a snorkel, I was thinking of removing the oval filter and sheeting around the filter area and then coming off with a 4" outlet.
Ebay has 4" enclosed pod filters that claim 700cfm ail flow, then through the guard using 4" tube to the top of the windscreen.

will this setup work and are the sizes ok for the 454. CFm calculators show for 100%VE at 5500rpm i need 720cfm,

thanks in advance

Re: need help with snorkel size on GQ with 454

Posted: Tue Oct 25, 2011 10:06 am
by toughnut
Apart from looking great. Wouldn't it be easier to box in each pod filter on each side of the engine and then run 2 snorkels? A 4 inch snorkel makes for a pretty big blind spot. The other thing you can do is think about the routing of the snorkle/s. Going through the guards creates a couple of problems that can be overcome by routing them differently.

Firstly you have more tight bends if you route it through the guards. It also pushes the snorkel to the outside of the guard where it can be easily damaged.

The other option is to route the snorkels up through the rear corner of the bonnet. This way you can minimise the bends in the pipe work and you keep it away from the edges of the vehicle until you run it up the 'A' pillar.

The sizes you are talking about are fine and running a single 4 inch snorkel and single pod filter. If you decided to go for a twin snorkel set up then you could go with 2 smaller pod filters and twin 3 inch snorkels. It would look more balanced and would also balance the flow of air to the mixers better but is a bit more work and will take a bit more space in the engine bay but will give better results.

Just some food for thought that I'm sure you've already considered.

Re: need help with snorkel size on GQ with 454

Posted: Tue Oct 25, 2011 10:17 am
by ANDREWGQ 351
I didnt want 2 snorkels as i dont think that it would look rite, it may be better ballanced though, the problem with running out the drivers side is the lack of space due to the main battery, water bottle and brakes in the way

Re: need help with snorkel size on GQ with 454

Posted: Tue Oct 25, 2011 11:25 am
by toughnut
No worries. The numbers that you've done are fine. You shouldn't have any problems.

Re: need help with snorkel size on GQ with 454

Posted: Tue Oct 25, 2011 10:49 pm
by purplebus
I am running a 454 injected vortec as well... :armsup:
was told by the dyno guys that anything under 4'' is a waste of time.
I will be doing ( my mate Paul who can built these) a double 3'' up through the corners of the bonnet into an airbox with a internal pod hopefully, but will be ages yet..

this is the old bus with a 3'' snorkel through the bonnet. pic wont show up sorry, heres the link.

http://s827.photobucket.com/albums/zz19 ... llter8.jpg" onclick="window.open(this.href);return false;

here is the link to the burnouts last weekend. the clutch wouldnt hold 3rd and kept slipping. you can see the smoke as we move of the line and grab 3rd. had to go 2nd. rear locker wouldnt re-engage for some reason. 1st time out with the commo boys and had a blast..


http://www.youtube.com/watch?v=0HHRhE0A ... re=related" onclick="window.open(this.href);return false;

Re: need help with snorkel size on GQ with 454

Posted: Wed Oct 26, 2011 6:31 am
by ANDREWGQ 351
nice video, mine is more of a tow truck that can now pass others up any hill, unlike the old 4.2, it can still melt the tyres thouhg.
i am currently changing the cam to a 225 at 50 duration so that should wake it up a little.
What size exhaust do you have, i have a 2.5" single but are considering changing to 3" mandrel with a flowmaster 70 muffler.

Re: need help with snorkel size on GQ with 454

Posted: Wed Oct 26, 2011 11:48 am
by purplebus
a mate of mine (Paul again) modified mine for me. He is ShortyIQ genius :armsup: :armsup: it originally came with the headers but the diff hit them and smashed the starter motor and bingo fire in eng bay. make sure you use a proper holden starter as the multifit ones off ebay are a curse.depends on what conv kit you have. mine is a markes kit and i used a 5.7 holden starter with the offset holes. he has remade the drivers side to run forward. they are 4x 2'' pipes for the each side joining to 2 x 2 1/2'' running accross the front of the engine around and all pipes joining to a 3'' single pipe with a very open muffler to a dump pipe at the diff.

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Re: need help with snorkel size on GQ with 454

Posted: Sat Oct 29, 2011 3:33 pm
by vanbox
toughnut wrote:Apart from looking great. Wouldn't it be easier to box in each pod filter on each side of the engine and then run 2 snorkels? A 4 inch snorkel makes for a pretty big blind spot. .
I have twin 4" on my GU and I can barely see them from the drivers seat. Definitely not a blind spot!

A GQ would be worse though. I had twin 3" on a GQ and could see them about as much as the 4" on the GU

Re: need help with snorkel size on GQ with 454

Posted: Mon Dec 19, 2011 9:08 pm
by 440 BB
have you got a link to the ebay filters im having trouble finding them

Re: need help with snorkel size on GQ with 454

Posted: Tue Dec 20, 2011 12:59 pm
by Ricko
440 BB wrote:have you got a link to the ebay filters im having trouble finding them
Not sure - is it this one, it doens't look like it uses a pod filter though.
http://www.ebay.com.au/itm/PATROLDOCTA- ... 2eba08af21" onclick="window.open(this.href);return false;

Re: need help with snorkel size on GQ with 454

Posted: Tue Dec 20, 2011 2:07 pm
by 440 BB
http://www.ebay.com.au/itm/5-OD-ALUMINU ... 2a152e2aee" onclick="window.open(this.href);return false;