^ cool maybe when i get it then i will take it out and hone alittle on the inside to give it lil space

 

A general rule is that a bigger opening gives more flow and will be good for high speed/top end. A smaller opening will create more vacuum and give better acceleration. That's why a full bore race car that runs at Daytona gets beat on an autocross course....and a few other reasons....-Bob

your results may vary...

 

Yes ,drag engines are designed around power in the upper rpm range and autocross need a balance of mid and high rpm. Yet they can both use the same size T/B.I guess what we need to determine is what is considered big. I personally fell 68-70mm is big. 72 & up is huge for most hondas. I dont think you would see or fell any difference from a 68mm to 70mm t/b if switched.

 

My last sentence was "your results may vary"....and for good reason. I was talking about sheer volume of air going through an engine at top end at Daytona, versus a smaller volume of air during acceleration at an autocross.

Floor the gas with a smaller carb and smaller intake runners and it will accelerate sooner than flooring the gas with a huge carb and huge runners. Hugh openings will likely "cough" and then start accelerating......

Your post causes me to think that you are talking about drag racing which is not constant top end, versus autocrossing....usually not at constant top end, as well as not reaching and holding top end.......but reality is that if by testing, a person finds the right combination, for whatever they are doing, it cannot be denied that the combination works.........but until something is developed and tested, everyone has an opinion. Thanks for posting.-Bob
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If we were to explore this further,
Hugh turbo chargers will give you greater top end but smaller turbos will give you better acceleration according to some people......and some people say that if you put a huge turbo charger on a small engine, that it will be unable to use a huge volume of air and will run worse......

 

just to clear things up. if anyone knows anything about fluid dynamics. alot of factors come into play when choosing a throttle body size. your intake manifold, port work done,valve job,cams,compression. you want to have a certain level of velocity for your motor to be its most efficent. large throttle body,large intake manifold decreases air speed. disrupts air distribution,turbulence and ultimately atomization. just do some research and make sure all your components work with eachother rather than against eachother.

 

agreed. lol i was just about to say the same thing. the size of your plenum is a huge determining factor as to what tb size to go with. you can't just say one size is good and one size is bad. if i remember correctly if you have a bigger plenum you use a smaller tb and smaller plenum can use bigger tb...i'll go verify that and get back to you. although manifold sizing isn't the only factor, it is a very important one. i will say tho, i have the pro2's with a 66mm tb and s2 manifold and i wish i went bigger. that's why itbs are next on the list...

 

damn this was a kindda olddie already bought a 65mm i messure all my shit and bored my intake to it,altho i am running skunk2 pros so i need all the air i can get but thanks for more info

 

You wish that you went bigger for more top end?
What's the top end now? Can you make the fuel pump run out of fuel?-Bob