F22A1 to H23 Intake Manifold Swap Questions

[toycar]

the iabs do work and can make more power with them working depending on health of the engine mainly and camshaft choice secondly. the reason the iabs installed may make more power is runner length and plenum volume NOT because of the valve itself. the longer runners helps with low end power which is where the stock cam thrives. as soon as you change out to an aftermarket cam you'll want them removed.

But thats because a different cam will change valve lift/duration, which effects the pressure being drawn by the cylinder.


The longer runner allows velocity to build as well as pressure to be maintained while the engine is pulling so few cfm's of air. At a higher rpm, the cfm being moved through the engine is greater, so the secondary runners allow that increased flow as needed, when needed. There is a point with natural aspiration that pressure becomes the enemy. That is why the secondaries open up at the peak of the initial runners flow ability, so they do not become a choke point.



Its all about the pressure in the manifold. Same reason a 70mm TB is not a good idea on an otherwise stock f22. Its way to large in diameter, and so performance suffers. Why? Pressure and the lack there of.

[jdm92_accorn]

the turbulence the butterflies cause is bad no matter the rpm. if you delete the butterflies and block the shaft holes on the iab plate you will make more power all around, i promise. if you dont want to go that route then do it the right way get the black box and the actuator and a rpm window switch and try it that way.

[toycar]

the turbulence the butterflies cause is bad no matter the rpm. if you delete the butterflies and block the shaft holes on the iab plate you will make more power all around, i promise. if you dont want to go that route then do it the right way get the black box and the actuator and a rpm window switch and try it that way.

Its odd that you say you'll make more power all around.


Do you have a before and after dyno to compare? The common opinion, as well as what science suggests, is that the low end will suffer.


Curious if you have a dyno to compare?

[jdm92_accorn]

[GhostAccord]

Is this a comparison between the intake with the butterflies installed + fully open all the time. Vs The intake with the butterflies removed with holes plugged? Where there any other changes?

if it is a straight up comparison of with or without. From what I see these show that removing the butterflies and plugging the holes really doesn't effect things much in the bottom end.

If you compare the curves between the two, you can see that below 4000RPM it doesn't really look like you gain more than 1-2hp power. The power difference is after 4000-4200RPM. And the tq curve doesn't really change until after 5200-5500 RPM. If my memory serves me correctly 4700-4900 is actually where they are programmed to open.

[jdm92_accorn]

actuated by a msd window switch set to 4800rpm vs plates deleted. the butterfly plates themselves causes turbulence.

[Mishakol129]

actuated by a msd window switch set to 4800rpm vs plates deleted. the butterfly plates themselves causes turbulence.

Just took the butterflies out, was easy as 1 2 3. Did the holes make a whistling noise or did you plug them up? Someone on here suggested using jb weld for that.


Do you guys think that Honda made the IAB's in order to work with Vtec specifically? If so that probably explains why Accorn made more power without them, seeing that our cars do not have Vtec. Vtec operates a high rpm's, it is very possible that on the H23 the IAB's operate at the exact same time Vtec engages.

[Accrdwgnguy]

H23A1 does not have VTEC.

I'll have to remove my butterfly plate and leave in the spacer I made. See what happens

[Jarrett]

When you're driving your car you're not always at full throttle. If you're not at full throttle then you need a method of restricting flow to preserve velocity. If you remove the IABs then you've done away with that. This is especially detrimental on an unmodified engine. If you have the right supporting modifications that move the powerband higher up, fine. Otherwise, it's still going to be a loss other than MAYBE a full-throttle dyno run.

[Mishakol129]

When you're driving your car you're not always at full throttle. If you're not at full throttle then you need a method of restricting flow to preserve velocity. If you remove the IABs then you've done away with that. This is especially detrimental on an unmodified engine. If you have the right supporting modifications that move the powerband higher up, fine. Otherwise, it's still going to be a loss other than MAYBE a full-throttle dyno run.

But if there smaller intake space wouldn't the engine have to work harder to intake the air itself? I mean, there would be more restriction and the pistons would not intake air as fast. I hear velocity but what about restriction? It may slow down the whole process of intake, exhaust etc.

And could it be that Honda introduced the IAB's as a way to help gas mileage and not for performance? There should be an official document which describes the purpose and use of the solenoid, ECU activated IAB's. Never seen such a document though, all I hear is people saying what it is but having no actual proof...

[GhostAccord]

But if there smaller intake space wouldn't the engine have to work harder to intake the air itself? I mean, there would be more restriction and the pistons would not intake air as fast. I hear velocity but what about restriction? It may slow down the whole process of intake, exhaust etc.

Where are you getting the smaller intake space from?

The IAB's aren't there to restrict flow exactly. They are there to allow for two different tuned lengths of runners. The longer runners that are always open and are a tuned length (volume/wave pulse) for the low end. The shorter runners are tuned to maintain a flow to allow for quicker cylinder filling @ WOT. The bigger/longer runners are actually the restriction if you really want to look at it in terms of velocity and top end power restriction.

And could it be that Honda introduced the IAB's as a way to help gas mileage and not for performance? There should be an official document which describes the purpose and use of the solenoid, ECU activated IAB's. Never seen such a document though, all I hear is people saying what it is but having no actual proof...

There is.. It's in the Prelude and Accord Shop manual. It states that the "High torque at low RPM is achieved when the IAB valves are closed, whereas high power at high RPM is achieved when the IAB valves are opened".

It's all about runner length and pulse wave tuning, RPM and runner volume. I'm not going to get into that, it's been covered more than a few times. There is no need to reinvent the wheel here.

[GhostAccord]

Do you guys think that Honda made the IAB's in order to work with Vtec specifically? If so that probably explains why Accorn made more power without them, seeing that our cars do not have Vtec. Vtec operates a high rpm's, it is very possible that on the H23 the IAB's operate at the exact same time Vtec engages.

There are two engines with IAB's that are non VTEC. The Prelude's DOHC H23A1 and the CB7 Accord's SOHC F22A6. I think the activation has more to do with the camshaft design and the power band of the engine itself.

[jdm92_accorn]

The iab setup in theory is a good idea. But in reality it only marginally worked and that's why honda no longer mainsyreams in in the 4cyl market. It can work on a bone stock car but as you put an aftermarket header on you up the demand for air and now its a resriction.

[dj_ender]

The iab setup in theory is a good idea. But in reality it only marginally worked and that's why honda no longer mainsyreams in in the 4cyl market. It can work on a bone stock car but as you put an aftermarket header on you up the demand for air and now its a resriction.

I just want to clear up something, I can't tell from your posts if you were just using a gutted plate or removed the plate entirely. Can you elaborate?

[GhostAccord]

The iab setup in theory is a good idea. But in reality it only marginally worked and that's why honda no longer mainsyreams in in the 4cyl market. It can work on a bone stock car but as you put an aftermarket header on you up the demand for air and now its a resriction.

It works the same with bolt-ons. i.e aftermarket headers... If you up the demand for air you change the activation RPM.... it's why people make money tuning. Any time you change something to increase the volume or velocity of the air entering or leaving this air pump you need to make adjustments in order to achieve maximum gains.

iVTEC has kind of taken over the need for IAB's. I would say that has more to do with why newer performance I4 Honda engines don't use them. Now they just have electronically controlled intake valves to make the adjustments.

Take a look at some modern high performance street bikes..... They use both secondary throttles and they also have throttle plates in the exhaust collectors.....