Offroad-Express

hi all i have a hilux with a 350 chev in it i made a snorkel for it but its only 2inch which is to small as i have found out lol
what size pipe shud i use and anny body here with one on a chev powered 4x4 give me anny help thanks

sell it to me maybe???

I'm going to run a 3 inch snorkel on my 350 chev

What about two? just make another one for the other side?

Wopass breaths through 2 x 3" pod filters mounted off the carb, so thats 6" of breathing room.

Blackcruisers old LPG set up on his 383 used to breath through a 4" single pod filter type set up.

I wouldn't go under a 4", its all about CFM with these motors!!!!!

DieselBoy wrote:Wopass breaths through 2 x 3" pod filters mounted off the carb, so thats 6" of breathing room.

Not quite.
2 x 3" pipes has similar air flow to a single 4" pipe.

mint thanks guys will get some 4inch pipe and start to play

A good rule of thumb is to make it a little bigger than the throat size of ya carb.....same goes for a prefilter if you have one...make it slightly bigger as well so it doesnt act as a restrictor.

KiwiBacon wrote:

DieselBoy wrote:Wopass breaths through 2 x 3" pod filters mounted off the carb, so thats 6" of breathing room.

Not quite.
2 x 3" pipes has similar air flow to a single 4" pipe.

from a vague memory one 4" pipe = 4 x 2" pipe for cross section area,

cheers

Pedro wrote:

KiwiBacon wrote:

DieselBoy wrote:Wopass breaths through 2 x 3" pod filters mounted off the carb, so thats 6" of breathing room.

Not quite.
2 x 3" pipes has similar air flow to a single 4" pipe.

from a vague memory one 4" pipe = 4 x 2" pipe for cross section area,

cheers

Yep.
It's diameter squared.

2 squared = 4.
4 squared = 16 (which is four times four).

The 4" pipe has a little less than twice the area of two 3" pipes, but will flow the same or better because there's 50% less pipe wall for the air to drag against.

KiwiBacon wrote:

KiwiBacon wrote:

DieselBoy wrote:Wopass breaths through 2 x 3" pod filters mounted off the carb, so thats 6" of breathing room.

Not quite.
2 x 3" pipes has similar air flow to a single 4" pipe.

Yep.
It's diameter squared.

2 squared = 4.
4 squared = 16 (which is four times four).

The 4" pipe has a little less than twice the area of two 3" pipes, but will flow the same or better because there's 50% less pipe wall for the air to drag against.

Kool, thats something for the note book!!!!!!!

DieselBoy wrote:Kool, thats something for the note book!!!!!!!

Actual area is 3.141*diameter squared/4.
But if you're comparing two different pipes you can boil the size difference down to just diameter squared.

gimmemud wrote:What about two? just make another one for the other side?

I know someone else running the same motor as mine that uses x2 3 inch snorkels one on each side of his truck.
The way i see it. If the throttle body inlet is 4 inches? Why make it bigger? Having x2 snorkels might look cool. But I recon the more stuff bolted to the side of your truck, the more chances you have of it getting ripped off?

I seeked advice from the guy who dyno tunes my truck on this before I altered my snorkel. I did have a 3 inch job on it at one stage but when it was on the dyno it was proved that it reduced power, a lot.
So a 4 inch snorkel and airbox was made up. Dyno results proved I was getting maximum performance with or without snorkel. The only problem i came across with a 4 inch setup was finding a 4 inch air ram. I ended up finding one through "Canterbury Truck Spares". That's my 5c worth.

i think i need a bigger v8

petefj40 wrote:

gimmemud wrote:What about two? just make another one for the other side?

I know someone else running the same motor as mine that uses x2 3 inch snorkels one on each side of his truck.
The way i see it. If the throttle body inlet is 4 inches? Why make it bigger? Having x2 snorkels might look cool. But I recon the more stuff bolted to the side of your truck, the more chances you have of it getting ripped off?

I seeked advice from the guy who dyno tunes my truck on this before I altered my snorkel. I did have a 3 inch job on it at one stage but when it was on the dyno it was proved that it reduced power, a lot.
So a 4 inch snorkel and airbox was made up. Dyno results proved I was getting maximum performance with or without snorkel. The only problem i came across with a 4 inch setup was finding a 4 inch air ram. I ended up finding one through "Canterbury Truck Spares". That's my 5c worth.

The only reason for going bigger than the TB is because as you increase the length of a pipe it flows less so to keep the same flow you need to go slightly bigger the longer you make it. It isn't much but it can be a factor with a highly tuned motor.

Also I got my 4" ram head for about $25. ie cheaper than a normal 4x4 one!! Brand new from truck part supplier as well.

darinz wrote:

petefj40 wrote:

gimmemud wrote:What about two? just make another one for the other side?

I know someone else running the same motor as mine that uses x2 3 inch snorkels one on each side of his truck.
The way i see it. If the throttle body inlet is 4 inches? Why make it bigger? Having x2 snorkels might look cool. But I recon the more stuff bolted to the side of your truck, the more chances you have of it getting ripped off?

I seeked advice from the guy who dyno tunes my truck on this before I altered my snorkel. I did have a 3 inch job on it at one stage but when it was on the dyno it was proved that it reduced power, a lot.
So a 4 inch snorkel and airbox was made up. Dyno results proved I was getting maximum performance with or without snorkel. The only problem i came across with a 4 inch setup was finding a 4 inch air ram. I ended up finding one through "Canterbury Truck Spares". That's my 5c worth.

The only reason for going bigger than the TB is because as you increase the length of a pipe it flows less so to keep the same flow you need to go slightly bigger the longer you make it. It isn't much but it can be a factor with a highly tuned motor..

After the hours spent on the dyno I would say the LS1 I'm running is now, "highly tuned". Like I said. We found no difference in kWs at the rear wheels with, or with out the 4 inch snorkel. Any bigger is over kill.

One other thing is you need an air filter that can flow that amount of air efficiently, Look at the size of PeteFJ40's Airbox and he is running a K&N in it i think, this will also be a potential point of restriction on most 4x4's as very few needed to flow the amount of air the 350 wants so you may have to adapt some other airbox or get something custom made.

Pete has also dyno'd his truck more than once so I am sure his results are accurate.

Steve_t647 wrote:One other thing is you need an air filter that can flow that amount of air efficiently, Look at the size of PeteFJ40's Airbox and he is running a K&N in it i think, this will also be a potential point of restriction on most 4x4's as very few needed to flow the amount of air the 350 wants so you may have to adapt some other airbox or get something custom made.

Pete has also dyno'd his truck more than once so I am sure his results are accurate.

I've lost count how many times my 40's been on the dyno.
The air meter you're talking about Steve isn't present on both V8's I own. They measure the air flow but also reduce it. That's the reason both vehicles have been on the dyno so much. A mafless tune takes a lot more time to get right. But when it's right it flies.

petefj40 wrote:I've lost count how many times my 40's been on the dyno.
The air meter you're talking about Steve isn't present on both V8's I own. They measure the air flow but also reduce it. That's the reason both vehicles have been on the dyno so much. A mafless tune takes a lot more time to get right. But when it's right it flies.

Funny how over here they throw away the airflow sensor and rely on the MAP sensor in the manifold instead.
In the US they fit bigger airflow sensors, obviously because their emissions regs are tighter. But Aussie emissions regs are getting tighter and tighter too, they don't seem to fit oversize sensors.

Steve_t647 wrote:One other thing is you need an air filter that can flow that amount of air efficiently, Look at the size of PeteFJ40's Airbox and he is running a K&N in it i think, this will also be a potential point of restriction on most 4x4's as very few needed to flow the amount of air the 350 wants so you may have to adapt some other airbox or get something custom made.

Pete has also dyno'd his truck more than once so I am sure his results are accurate.

I guess I'm the only one running a restriction gauge on my airfilter. That way I know exactly how hard the engine has to suck through it. With the benefit of knowing when my filter needs cleaned.
I run a toyota 100 series air element in a home-made housing. It's enough to feed a 4 litre diesel with 20psi. Wonder what the turbo territories are running. They'll have one of the highest air consumptions of current engines.

KiwiBacon wrote:

petefj40 wrote:I've lost count how many times my 40's been on the dyno.
The air meter you're talking about Steve isn't present on both V8's I own. They measure the air flow but also reduce it. That's the reason both vehicles have been on the dyno so much. A mafless tune takes a lot more time to get right. But when it's right it flies.

Funny how over here they throw away the airflow sensor and rely on the MAP sensor in the manifold instead.
In the US they fit bigger airflow sensors, obviously because their emissions regs are tighter. But Aussie emissions regs are getting tighter and tighter too, they don't seem to fit oversize sensors.

There are other sensors all over the LS motors, knock sensors, air temp sensors etc. The air flow sensor is great for trimming the fuel on cruise control and telling you if the air filter needs changing etc. But if you are after max hp and aren't after the best fuel economy and clean your air filter regularly there is no advantage to having one. Granted, the motor needs a shit load of tuning before the tune is sorted with out a airflow sensor. But as I've found, the horse power gain is very substantial. The economy goes out the window. If you want heaps of hp, economy is the last thing on your mind.