Will more efficient heads utilize a bigger carb/throttle body?

[thomas butt]

Take two engines with same displacement same intake similar or same cams yet two different heads each capable of using the size of engine and cam but one set of heads are highly developed race heads and the other set are ported factory pieces that work very good but might not make as good of power. Will each engine use a different carb/TB to make best power for their respective set up?

[B Original]

Take two engines with same displacement same intake similar or same cams yet two different heads each capable of using the size of engine and cam but one set of heads are highly developed race heads and the other set are ported factory pieces that work very good but might not make as good of power. Will each engine use a different carb/TB to make best power for their respective set up?

Your hypothetical needs to be more specific to get a good response

[MadBill]

The increased airflow of the better-developed heads should produce a higher WOT manifold vacuum and to a considerable extent driveability is proportional to same, so it could be argued that the higher power combination could utilize more carb flow for a given 'driveability index'. (If there was such a thing.)

[pcnsd]

Take two engines with same displacement same intake similar or same cams yet two different heads each capable of using the size of engine and cam but one set of heads are highly developed race heads and the other set are ported factory pieces that work very good but might not make as good of power. Will each engine use a different carb/TB to make best power for their respective set up?

My experience is that all sub-component designs need to target the application. If one component is more capable than another, then the lagging component(s) become the limiting factor. Improving cylinder heads in airflow or chamber dynamics will not significantly improve performance if the other components are incapable of capitalization. Adding a better designed TB will either improve or fail both systems in question depending on the other factors present. In a well developed motor, it is easier to lose performance than to gain.

[thomas butt]

Take two engines with same displacement same intake similar or same cams yet two different heads each capable of using the size of engine and cam but one set of heads are highly developed race heads and the other set are ported factory pieces that work very good but might not make as good of power. Will each engine use a different carb/TB to make best power for their respective set up?

I wanted to add that an additional constant would be intake/exhaust port size. Say the intake & exhaust are more than capable & appropriate for both heads, will the head making more power naturally need bigger jet sizes or bigger TB or will the efficient head utilize the same size carb better? I am an amateur and no engine builder. I just thought of this earlier today and wondered if there would be a different requirement for each head fuel wise

[Geoff2]

Intake manifold also plays a part. It could become the 'choke' with better flowing heads, so bigger carb does nothing because the intake chokes the flow.

[Scotthatch]

Take two engines with same displacement same intake similar or same cams yet two different heads each capable of using the size of engine and cam but one set of heads are highly developed race heads and the other set are ported factory pieces that work very good but might not make as good of power. Will each engine use a different carb/TB to make best power for their respective set up?

I wanted to add that an additional constant would be intake/exhaust port size. Say the intake & exhaust are more than capable & appropriate for both heads, will the head making more power naturally need bigger jet sizes or bigger TB or will the efficient head utilize the same size carb better? I am an amateur and no engine builder. I just thought of this earlier today and wondered if there would be a different requirement for each head fuel wise

The wording of your question is making it difficult for people to answer ....

Fuel is different than air and injection is different than carburetor...

Air ...... the whole system has to flow enough to support the head ... you put big heads on with stock intake the gain will be very low ... on my dodge truck just fixing the throttle body restriction gained me power

Fuel ... if a carburetor has enough airflow to support the change then it will give you more fuel ...fuel injection if you add more air you need to add more fuel how this happens depends on if the computer can deal with the change and how close to 100 % cycle the injectors are

Efficiency...... if you make the chamber more efficient the fuel demand goes down

[groberts101]

Based on your wording.. I'd guess that VE would improve at least some small amount and be as Bill already mentioned above. It would also stand to reason that the same cam may act slightly larger with a more efficiently flowing cylinder head and allow more rpm capability vs the decently flowing head.

In order for neither of those scenarios to play out in reality.. I would guess the intake manifold would have to be right at the verge of choking off the decently flowing heads before the well sorted head swap was done.