Author Topic: Air flow into an L series  (Read 531 times)

Offline .

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Air flow into an L series
« on: November 04, 2011, 10:49:00 AM »
Does anyone know what sort of air flow is generally required to run an L series?

I grabbed a calculator of the net and applied the details of my engine and it comes out at 2,968 CFM at 1000 RPM up to a whopping 38,000 CFM at 8500 RPM.

That sounds over the top to me.....any thoughts?

I have an idea that would boost air pressure in the intake like a turbo but would not require any fan blocking the intake. But by my calculations it would be a stretch to achieve 38,000 CFM. But on the plus side there is no restriction required so even if it only supplied modest boost at low revs there is no down side at high revs.

Offline Scoota G

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Re: Air flow into an L series
« Reply #1 on: November 04, 2011, 02:45:34 PM »
Check the CFM delivery of a 45mm Carb (think it's just below 400 CFM). If an L series Needed more than that it would have to have a bunch of mods done to it.
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Offline benny

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Re: Air flow into an L series
« Reply #2 on: November 04, 2011, 03:10:16 PM »
Woo hoo, you are spot on. I have checked and you are correct around 400 CFM but that is per venturi so its around 2400 CFM total. My idea is totally achievable then :)


you sound like an evil scientist at the moment Greg!!

Offline dat2kman

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Re: Air flow into an L series
« Reply #3 on: November 04, 2011, 04:31:48 PM »
a piston is a pump in a cylinder.
the cylinder is not closed a lot, it has valves that are controlled by a cam, with overlap between exhaust and intake.
It is surprising how much fresh fuel air charge can escape out the exhaust port at rpm.
I flow plenty through a single 50 mm L28 injection throttle body, as much as any triple weber carbed, or a SU carbed car, it is all dependant on which pistoon pump is drawing air, and how much.
I just race old datsuns:
Group S Historic 280Z ( not a zx but a USA 280z)
Group O/T Historic Datsun Sports 2000
Group G Datsun 120y  with FJ24 fitted( ex G. Fury)
Marque Sports Datsun Fairlady 1966 -SR20DET

Offline peter mc

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Re: Air flow into an L series
« Reply #4 on: November 04, 2011, 05:04:57 PM »
mmm you need a 95mm throttle to flow 6, 45 Weber's just to match the cfm and then you need the manifold to flow that air ,,, but there is more going on then air flow when you look at manifold volume, and some times the single 50mm will make more torque through the range ,,,but if you go to big on the throttle you will not have good control of idle and it will be a pig to drive this is where the ITB start to work and if you wont it to rpm and make power in the top the ITB kick ass
one more thing to think about the port when worked over flows about 230cfm and with a single throttle manifold with lots of work ..the port now flows about 190cfm ,and with a big port race weber manifold and carb it flows 220cfm
« Last Edit: November 04, 2011, 05:14:57 PM by peter mc26 »

Offline dat2kman

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Re: Air flow into an L series
« Reply #5 on: November 04, 2011, 05:15:34 PM »
Hey Pete, I have to use it, Group S Historic prod sports rules, so i just make it the almost best it can be. I have done more airflow testing on some things not yet fitted, they comply with rules, i just need certain things done to the inside of certain things, yes secret squirrell, stuff, but i have a competitor trying to do one the same, so we are all a bit sshh sshh!
what a bloody giggle this all is, the sheep stations we race for are SSSOOOOOOO HHHHUUUGGGEEE!!!
I just race old datsuns:
Group S Historic 280Z ( not a zx but a USA 280z)
Group O/T Historic Datsun Sports 2000
Group G Datsun 120y  with FJ24 fitted( ex G. Fury)
Marque Sports Datsun Fairlady 1966 -SR20DET

Offline peter mc

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Re: Air flow into an L series
« Reply #6 on: November 04, 2011, 05:28:16 PM »
heheheh i no but its fun
and i have seen how fast your car is so you now how to play there game ...and i am in awe of peter halls car and him as he is so fast with so many dumb rules ,,he was telling me that he picked up 50hp on his car since he went to 3 44 carbs over the 240 carbs ,but its not all about the engine the hole car is a package and you need to put the power to the ground and its often over looked in the search for more power
« Last Edit: November 04, 2011, 05:35:09 PM by peter mc26 »

Offline MaygZ

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Re: Air flow into an L series
« Reply #7 on: November 04, 2011, 05:30:35 PM »
With my new engenious invention I will make every turbo and supercharger obsolete and I will take over the world, Nwwaaa ha ha ha ha haaaaaa!!!! (queue image of big, scary guy flexing his long fingers together)
Zeds are more fun than women!!   You know I'm right, but you're too scared to admit it!!

http://www.viczcar.com/forum/index.php/topic,7841.0.html

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Re: Air flow into an L series
« Reply #7 on: November 04, 2011, 05:30:35 PM »