Individual throttle bodies for K20 YUMMY...
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Joined: Apr 2002
Posts: 144
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From: San Diego, CA, USA
Re: Individual throttle bodies for K20 YUMMY... (1 Special CTR)
that looks like the mugen (i thnk) itb for the b18........ what size are those? from my estimates, even 50mm tb's wouldn't be enough for our engine.
Re: Individual throttle bodies for K20 YUMMY... (merlyn)
From the mods you have listed, you don't need anything bigger than 50mm.
Ok, say you have a 65mm throttle body stock. Thats a little over 15mm for each cylinder. Now you have individual throttle bodies and thats 50mm for each cylinder, do the math.
Ok, say you have a 65mm throttle body stock. Thats a little over 15mm for each cylinder. Now you have individual throttle bodies and thats 50mm for each cylinder, do the math.
Honda-Tech Member
Joined: Dec 2001
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From: Colorado Springs, CO
Re: Individual throttle bodies for K20 YUMMY... (SuperStreetRX7)
Ok, say you have a 65mm throttle body stock. Thats a little over 15mm for each cylinder. Now you have individual throttle bodies and thats 50mm for each cylinder, do the math.
Brian
Joined: Apr 2002
Posts: 144
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From: San Diego, CA, USA
Re: Individual throttle bodies for K20 YUMMY... (MJ23FE)
Even a 50mm setup offered by TWM is too small IMO. It will work fine for a basic street engine, but for really serious hp, it just won't do.
You need to examine the displacement per cylinder to see just how big the TB's should be. With a K20, we're looking at 500 cc per cylinder. This is on par with the big liter twins like the SP2 and Ducati 998. The SP2, in preparation for homologation and racing setup, uses _62_ mm throttle bodies!!
I know of several race teams in import drag racing that won't use the available ITBs on their all-motor cars because they'd lose power vs. their optimized intake manifold setup. Not because an intake manifold is better, but because the ITBs just won't flow enough.
How many cylinders are breathing from the intake plenum at one time on an I4 engine? In reality, its one. But because of the close proximity of intake pulses at high rpm, you might consider it to be the equivalent of 2 cylinders at one time if the plenum is small.
On a top all-motor Honda engine, you're looking at TB's of 70-75mm in diameter. Combine that with a large intake plenum (say 2.0 liters) and each cylinder is basically breathing through a big throttle body by itself.
The problem with such huge throttle bodies and plenums is that you're killing throttle response and low rpm/light throttle flow velocity. Going with smaller individuals gives you back all that part throttle and low rpm power/response while giving you all the top end you want (assuming proper sizing). Additionally, the shaping of the flow path on ITBs tends to be far more ideal than your typical intake manifold (although the RSX-S manifold is really, really good for an OEM).
You need to examine the displacement per cylinder to see just how big the TB's should be. With a K20, we're looking at 500 cc per cylinder. This is on par with the big liter twins like the SP2 and Ducati 998. The SP2, in preparation for homologation and racing setup, uses _62_ mm throttle bodies!!
I know of several race teams in import drag racing that won't use the available ITBs on their all-motor cars because they'd lose power vs. their optimized intake manifold setup. Not because an intake manifold is better, but because the ITBs just won't flow enough.
How many cylinders are breathing from the intake plenum at one time on an I4 engine? In reality, its one. But because of the close proximity of intake pulses at high rpm, you might consider it to be the equivalent of 2 cylinders at one time if the plenum is small.
On a top all-motor Honda engine, you're looking at TB's of 70-75mm in diameter. Combine that with a large intake plenum (say 2.0 liters) and each cylinder is basically breathing through a big throttle body by itself.
The problem with such huge throttle bodies and plenums is that you're killing throttle response and low rpm/light throttle flow velocity. Going with smaller individuals gives you back all that part throttle and low rpm power/response while giving you all the top end you want (assuming proper sizing). Additionally, the shaping of the flow path on ITBs tends to be far more ideal than your typical intake manifold (although the RSX-S manifold is really, really good for an OEM).
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