Independant Throttle Bodies (ITB's/IRTB's)
- Thread starter flat_black
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I've been reading through this thread and doing a little searching on the net, but I can't find good answers. I see having 4 mid-sized throttle bodies is good since it gives you a much larger area overall but doesn't sacrifice low-end power.
I'm curious on how exactly they work, or maybe just some good pictures of them installed in a car similar to ours. They need a howstuffworks page for ITBs
I'm curious on how exactly they work, or maybe just some good pictures of them installed in a car similar to ours. They need a howstuffworks page for ITBs
khaosman said:I've been reading through this thread and doing a little searching on the net, but I can't find good answers. I see having 4 mid-sized throttle bodies is good since it gives you a much larger area overall but doesn't sacrifice low-end power.
I'm curious on how exactly they work, or maybe just some good pictures of them installed in a car similar to ours. They need a howstuffworks page for ITBs
Here's TWMs website.
http://www.racetep.com/twm2000.html
Here's a Miata with some IRTBs.
http://forum.miata.net/vb/attachment.php?attachmentid=1555
http://forum.miata.net/vb/attachment.php?attachmentid=1556
Just picture that sideways for a Protege.
There's not anything mystical about how they work. Instead of having one throttle body, a plenum and 4(or 8) intake runners, this setup has 4 intake runners, each with a single throttle body, and one velocity stack/horn per runner. You can make the the runner's diameter small enough to aid low RPM velocity, but because of the low restriction, high-flow nature of individual throttle bodies, you don't choke off high RPM power. Check out this dyno of a 1.9 litre Miata BP with stock cams. It still makes 125lb-ft, but look how much high RPM power it makes on the stock cams.
http://forum.miata.net/vb/attachment.php?attachmentid=3674
Throttle response is second to none, as the volume of air past the throttle bodies is minimal. Once you hit the throttle, it takes almost no time for air/fuel to enter the combustion chamber. With a typical single throttle body/plenum/runners(or dual runners) setup, air takes time to get moving into the combustion chamber once the throttle is open, since air is elastic.
Then there's the sound. There is no way to make your car sound better, than with IRTBs. Here's a Miata with them:
http://www3.telus.net/terence_chu/coolstuff/irtb.mpeg
I hope that answers all your questions.
flat_black
Member
Finished 'em, but I'm rebuilding a new set. Need to order a new ECU at the end of January.
flat_black
Member
Me, so far. I've made two sets. The second is still waiting for a mount for the manifold, though. Hint: Use 45mm to 48mm runners. The 42's I had before weren't really large enough.
I'm still waiting for a standalone ECU, but once I get that, I'll post results. You'll need a standalone, too, if you want to run ITB's.
I'm still waiting for a standalone ECU, but once I get that, I'll post results. You'll need a standalone, too, if you want to run ITB's.
flat_black
Member
Yep. You're still removing the EGR, and such, at that point. Lots of emission control stuff goes away with the ITB setup.
flat_black
Member
MAP is pretty easy to run off a vacuum manifold, and so on, thankfully.
flat_black
Member
I'm not sure if I can do it right yet, but the price will be pretty steep... Over 2.5k, most likely.
This would include four total (Twin DCOE) throttle bodies, with a cast lower manifold to which that attaches. Then the fuel rail on top of that, ported for 11mm Japanese-style injectors, linkages between the throttle body sets, and a properly angled double sprung throttle cable linkage. Most of the assembly is aluminum. This would come with stacks to make the runners aproximately 11" in length total, and you'll need motor mounts to avoid that hitting the firewall. A fuel pressure regulator would also be included, and a vaccuum tree, plus vac ports on the underside of the intake runners.
I really wish I could take some pics of it, but yet again, my camera is dead. Which pisses me off a lot, since I have a head that's being done up, too.
This would include four total (Twin DCOE) throttle bodies, with a cast lower manifold to which that attaches. Then the fuel rail on top of that, ported for 11mm Japanese-style injectors, linkages between the throttle body sets, and a properly angled double sprung throttle cable linkage. Most of the assembly is aluminum. This would come with stacks to make the runners aproximately 11" in length total, and you'll need motor mounts to avoid that hitting the firewall. A fuel pressure regulator would also be included, and a vaccuum tree, plus vac ports on the underside of the intake runners.
I really wish I could take some pics of it, but yet again, my camera is dead. Which pisses me off a lot, since I have a head that's being done up, too.
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twilightprotege
Member
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- 2001 323 Astina SP20 (P5)
look what i found : http://www.boostcruising.com/readersrides/entry/6/10515.html
the guy is from my city, but no idea who he is or what else is done to the car, but the quads look very nice
the guy is from my city, but no idea who he is or what else is done to the car, but the quads look very nice
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