Aftermarket or alternative t/b and intake

[ctchme]

Hey guys,
Just wondering if there is any aftermarket throttle bodies for an NA8, or if there are throttle bodies from different engines that can bolt on, and same for intake manifold??

[NitroDann]

The real question is Why?

Dann

[project.r.racing]

94-97 Mazda 323 Astinas (1.8) and Proteges (1.8), 94-97 Ford Laser GLXis and Lynxs run the same throttle bodies.

[ctchme]

The real question is Why?

Dann

because a larger tb and/or intake improves the flow of air into the engine, have done it on my n12 turbo, gotten a jap spec intake and a larger tb, and it improved the running of the engine, and slightly increased hp, due to the fact it was taking more air in

[Matty]

The subtext of Dann's question is that the throttle body isn't a significant restriction on an otherwise unmodified MX-5. It's already 55mm. You'd need to open up the rest of the breathing (more than just intake and exhaust) before the TB is worth doing. Same for the intake manifold, unless you want snappy throttle resonse from some quads (which again would need lots of other work to justify)

[NitroDann]

What matty said.

Cheers (ever considered being a professional interpreter?)

Dann

[Okibi]

Matty do you have a link to that "free flowing an MX-5" article you did?

[Steampunk]

Matty do you have a link to that "free flowing an MX-5" article you did?

Voila!
http://autospeed.com/cms/A_110680/article.html

[NitroDann]

There was a vast discussion that I was a major part of on miataturbo, where a bloke asked what he should expect from going to quad throttle bodies on a stock na8. I told him he would expect no straight line improvement. He couldnt believe that removing the TB 'restriction' that no improvement would be made. But imagine your standing in a queue to buy a movie ticket, and the line goes out the door, making the door 10% wider wont get you in faster will it?

Dann

[PaulF]

There was a vast discussion that I was a major part of on miataturbo, where a bloke asked what he should expect from going to quad throttle bodies on a stock na8. I told him he would expect no straight line improvement. He couldnt believe that removing the TB 'restriction' that no improvement would be made. But imagine your standing in a queue to buy a movie ticket, and the line goes out the door, making the door 10% wider wont get you in faster will it?

Dann

This interests me. I presume what you're saying is that there are other things which restrict the flow of air more than the throttle body in an MX-5 engine. You say "no straight line improvement" - would there still be an improvement in response time or something? Because it's a fairly popular mod to be achieving no improvement.

[Okibi]

Usually with ITBs you might loose some low down but you'd gain peak power ... quicker in a straight line really depends how long the bit of road is.

[NitroDann]

The owner of the 180hp 1.6 Ae86 with itb's disagrees.

You wont gain anything up the top from quads over an adequate single throttle intake, you also wont lose bottom end. All of that has to do with runner length, the same applies to IM's.

You do gain response though.

Larger throttle bodies on a mostly standard (say.. less than 1.3 times stock power) engine will rarely increase power (definately not on an mx5, they have decent sized TBs).

Ill give you a test you can do yourself to find if they are big enough. This test works awesome with a 3.8 commodore as those cars have so many design cheats that non enthusiasts fall for. Like a huge TB.

Drive along the road in a high gear, say 4th at 50 kph. now increase the throttle to 50% and feel the power. Now repeat it but before its accelerated a lot increase it to full throttle. ie: start at half and 3000rpm, now snap it to full at 3500 and you will notice NO power difference, because the throttle plate is large enough to flow enough air for the car at just half throttle. Now do the same test instead with 3/4 throttle and full throttle at maximum power revs.

Again, no difference between full and 3/4 throttle. seriously test it. Thats because a stock mx5 TB flows enough air to not be a restriction at only 3/4 throttle standard.

Imagine the air flow hole that a stock TB (55mm) allows at full throttle, now imagine how little throttle plate angle is needed to achieve this airflow with a dinner plate sized throttle body. You essentially achieve maximum throttle with just 2 mm of throttle on the pedal.

This is the reason people think there car is faster with a larger TB, its because we get the same flow with less throttle used, so the car seems to have gained power, but it achieves the same power at half throttle as the old TB did at full, and no more anywhere past that.

Dann

[Okibi]

...You wont gain anything up the top from quads over an adequate single throttle intake, you also wont lose bottom end. All of that has to do with runner length....

A lot depends on what else has been done to the engine/exhaust to help remove any restrictions to see how effective ITBs are, I guess the debate here is at what point the stock throttle (and plenum) stop being "adequate".

The diameter of the throttle body and trumpet also effects where the engine makes more or less power than stock.

[Matty]

...You wont gain anything up the top from quads over an adequate single throttle intake, you also wont lose bottom end. All of that has to do with runner length....

A lot depends on what else has been done to the engine/exhaust to help remove any restrictions to see how effective ITBs are, I guess the debate here is at what point the stock throttle (and plenum) stop being "adequate".

The diameter of the throttle body and trumpet also effects where the engine makes more or less power than stock.

I think Dann was treating the runner length and diameter as a separate variable from the throttle position and number. Of course, moving to quads gives you the ability to actually change those, that the standard manifold doesn't. But theoretically it would be possible to make a single-throttle manifold with equivalent runners.

My intake article is of no relevance here, I didn't test the throttle body. It can be done in a similar fashion but you need a few more hands and a valve to stop your manometer being sucked empty... Or an accurate differential pressure gauge

[Steampunk]

Yeah IRTB's are junk, anyone who even considers putting a set on are simply clueless and inept.