Throttle body size effects

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Joined: Thu Dec 31, 2020 9:41 am

Throttle body size effects

Postby JEALES » Mon Jul 04, 2022 8:22 am

Hi guys,

Just wondering if anyone on here has some insight into throttle body sizes on small 4 cylinder engines.

I upgraded my Suzuki G13B Throttle body to an 65mm SR20 version, which is pretty much a direct bolt on (OEM G13B is 45mm )

People are still making really good power with the 45mm throttle, but I thought bigger is better and already had my intake apart.

Upon installing it, Ive noticed that the power drops off after initial spool. Doesnt matter how much boost you.throw at it, it still seems to dull off. From about 4000-6000 then comes back alive after 6K. The initial spool up/2500-4000 pulls really hard, then it just seems to make all the boost but you can really feel it not go anywhere.

Ive checked timing and AFRs seem pretty reasonable ( 11.2 @ 18psi )

I am just wondering if the bigger throttle body could be causing air velocity issues seeing as its such a smaller engine.

Apologies for my lack of knowledge in this department.

Is there anything else I could be missing on the setup?

Thanks in advance.


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