70mm too big?

[Vtechno]

my previous post has been edited.

[TheNextEpisode]

when most people my age go out and get wasted on the weekends, i read about stuff liek this. cause im a nerd, lol.

Yeah fluid mechanics wins out over getting wasted any day.


hmm.. yeah I meant 5 hp+, not 55 hp+. That was a horrendous typo.

But yeah, I hear you regarding the research Honda, and pretty much all car manufacturers, puts into their engines. I remember reading an article in super chevy where they built a rat motor. They tried endless combinations of aftermarket parts and then engine dyno'd it after each modification, and with different modification packages. Most often, the more mild modifications won out dramatically. 1200 cfm carbs were heavily outperformed by 650 cfm carbs and so on.

That type mentality that bigger=better is a shame to engine tuning.


I'd hope to have a modest H at the end of the day, with my normal I/H/E modifications, a pending intake manifold, throttle body, and gasket combo, hopefully bisi H headers, and my delta 262 cams. (Maybe type s pistons, if I have to tear down the engine again.) With that in mind, I wouldn't expect to have a real high power band, so yeah, something like a skunk2 pro series manifold might be a little inappropriate for me.

Those Blacktrax spacers are looking more and more tempting. Maybe I should stick with those, at least until the rest of my engine is deserving of a freer flowing IM. AHHH I can't wait to receive my ecu from MRX.



Wait, maybe we're talking about the same Chevy magazine engine build.

[F20A CB7]

THIS is a NEWBII question, but what is the Bore for the F22A motors

[TheNextEpisode]

cylinder bore is 85 mm

throttle body bore is 60 mm

[F20A CB7]

SO what needs to b done to have maxium flow, bore out the cylinder to 60mm to match the throttle bore

[TheNextEpisode]

Oh hehe, nah, I only mentioned cylinder bore cause I wasn't entirely sure which bore you were referring to.

What the original poster was referring to was the throttle body bore.

Throttle Body

It's the thing right in the middle of the picture, with the golden butterfly valve. When you apply pressure to the throttle pedal, you are actually opening that golden butterfly valve so that air can enter the combustion chambers via the intake manifold.


Basically, the stock inner diameter of that circular passage is 60 mm. Since all air entering the combustion chambers must go through this circular passage, some people like to bore out (make the inner diameter larger) their throttle bodies so that when throttle is applied, more air will be able to flow through that larger diameter circular passage.

Then the thing owequitit was referring to was port matching. Like I was saying earlier, air, modulated by how far open you have the butterfly valve, will pass through your throttle body and into your intake manifold. However, if you have your throttle body bored to a larger diameter, the complementary hole on the intake manifold will still have the inner diameter of your original throttle body. By port matching your intake manifold, you are trying to enlarge the smaller diameter hole on your intake manifold so it will match your newly enlarged throttle body bore.

If you didn't port match your intake manifold, then your bored throttle body would be nearly ineffective, since its point was only to increase flow. If your intake manifold wasn't port matched, the intake manifold's hole would still be small and air flow wouldn't be increased.

[simpL cb7]

I have seen someone weld on a Q45 90MM TB onto a JDM Manifold. Sick job.

[Camurai]

To get maximum flow, you'll have to match all of your components. owequitit put it pretty well. Each item that you upgrade is part of a system. Every part will affect how every other part operates. If you're going to put a huge throttle body on your car, you're going to have to do a lot more work to realize the maximum potential of that part. You have to take into consideration: your intake manifold, cylinder head, cams, cam and ignition timing, compression ratio, fuel pump, injectors, fuel rail, and your entire exhaust system. The entire powertrain is in a delicate balancing act, and if you upset the balance by adding one grossly exaggerated part, you're going to be severely disappointed with the results. Every part is a piece in a giant puzzle.