Intake runner length....technical question
#1
Lexus Test Driver
Thread Starter
Intake runner length....technical question
So, as some folks may remember I've been designing an intake system thats gonna be really cold air and blah blah blah....but right now I'm focused on the intake length to keep the max torque in the 4800 rpm area just like stock.
According to my calculations the length from the valve opening to the tip of the intake tube should be about 2.6 ft. My question is this: what is the total length from the throttle body to the intake valve opening. I have no real way of measuring that and would appreciate one of you more technical fellas (**COUGH loboxracer COUGH** ) pointing me in the right direction.
According to my calculations the length from the valve opening to the tip of the intake tube should be about 2.6 ft. My question is this: what is the total length from the throttle body to the intake valve opening. I have no real way of measuring that and would appreciate one of you more technical fellas (**COUGH loboxracer COUGH** ) pointing me in the right direction.
#3
Don't forget that the intake is dual stage and therefore the lenght is dependent on the baffle postion. Sounds like you want the maximum lenght regardless but it could be better to consider both low and high RPM conditions.
#4
Tech Info Resource
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Total length from the throttlebody to the intake valve isn't the important part of this because you have a plenum supporting the intake runners. The length you're wanting to manage is the runner length. 31 inches sounds like a lot of runner - you might want to consider half wave (16.5 inches) from a packaging perspective.
Who's calculator are you using for this?
Who's calculator are you using for this?
#5
Tech Info Resource
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This is only true for the 4GR-FE, it is not true for the 2GR-FSE.
#6
Lexus Test Driver
Thread Starter
Total length from the throttlebody to the intake valve isn't the important part of this because you have a plenum supporting the intake runners. The length you're wanting to manage is the runner length. 31 inches sounds like a lot of runner - you might want to consider half wave (16.5 inches) from a packaging perspective.
Who's calculator are you using for this?
Who's calculator are you using for this?
but then this would move the torque curve significantly below the 4800 mark.
#7
Lexus Test Driver
Thread Starter
now heres the funny thing...according to the calculations, with a displacement of 210.5 cubic inches and the supplied 4800 max torque rpm (from lexus) it says the frontal area should be 1.9 square inches. The stock intake frontal area is practically 3 inches squared. Why supply 1/3 more frontal area than is needed?
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#8
Tech Info Resource
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now heres the funny thing...according to the calculations, with a displacement of 210.5 cubic inches and the supplied 4800 max torque rpm (from lexus) it says the frontal area should be 1.9 square inches. The stock intake frontal area is practically 3 inches squared. Why supply 1/3 more frontal area than is needed?
Yes, you can double the length and still have a viable piece, but you'll change the balance of harmonics at other frequencies. If the engine were designed to run at a specific rpm all the time (like a stationary generator set) then you could fully optimize intake length and gain some pretty impressive efficiencies. Since car engines have to run widely variable rpm, you have to make a best fit compromise. My bet is you'd be happier with the shorter length if you have any way you can make it work.
#12
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