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Peter-san, can you post links to sound files of IRTBs here?
 

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i have been tossing the idea around too, when i was at the 1996 Miata Games at Road Atlanta there was a guy with a set of these on his car. As he came out of the last turn (the one that is like driving off the face of the earth) He started to get back on the throttle........ hard .... at the apex of the turn, ugh....... It sounded so freaking sick!!! Just killer man, really...... It was a sound i would never forget.

There is a local Tuner here in Florida i want to visit, and he installs, tunes & races them, if i dont get a turbo this will be the way to go.

http://www.fuji-racing.com/fujiracing_004.htm

PhatMiata
 

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I'm still up in the air about these...seems without some motor work, they're almost like expensive noisemakers...
 

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What's to moderate when there is no content? Where is everybody? Sometimes I feel like I'm talking to myself here. I know, I know, give it time. If you build it, they will come.
 

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Gains?

i wanna know if its worth the money to get IRTBs. i know they sound cool, look cool, are cool... but is there really a huge gain on the HP end? i can imagine if you build the motor sure but what kind of numbers do you get with just bolting on the IRTBs? and what goes best with IRTBs?


:?: :?: :? :?: :?:
 

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Cornflake, your questions are a little basic for this forum but I will do my best to help you. It sounds like you're already a little bit in over your head so I would also suggest that you head over to Miata.net and type "IRTB" into the search function, toss a bag of popcorn in the microwave, and get comfy for many hours worth of reading. Much has been discussed at length providing excellent knowledge about IRTBs.

Sound cool: yes

Look cool: yes

Are cool: yes

Huge HP gain: yes, depends on your definition of huge and whether or not you have other mods to support the IRTBs. They alone might make 30-40hp if the original intake was a severe restriction and all the other necessary go fast mods are present.

HP gain everything else stock: 0 to 20hp to -10hp depending on tuning.

What goes best with IRTBs: RoadsterJDM.net, for one. Or how about a 2.0L stroker motor made of forged crank, forged connecting rods, forged high-compression (greater than or equal to 11:1) pistons, upgraded main bearing support, better oiling (perhaps better baffle tray, true high volume pump, Accusump, or dry sump), ARP hardware throughout, gasket matched everything, fully built head including larger titanium valves, solid lifters with shim under bucket design, titanium valve keepers, fully radiused valve seats, high performance valve springs, big cams, adjustable cam gears, high-strength timing belt, dual feed fuel rail, bigger primary injectors mounted outside the throttle plates, quality tuned header and exhaust system sans cat (otherwise you'll destroy it during tuning when running rich), thermal and friction reduicing coatings throughout, everything lightened, balanced, and blueprinted, a whole bunch of other secret pro engine builder tricks, killer standalone engine management, 100 hours dyno time with the assistance of a professional tuner, etc.

IRTBs just help the motor breathe better. If your motor can use the extra breathing capacity then you might realize some performance benefit from them. IRTBs can breathe hot, dirty air or they can breathe clean, cool air. They can provide the head with good intake velocity or the poor intake velocity. They can make power or they can rob power and driveability and fuel economy. It all depends on the other components in the system and how well the IRTBs are set up and how well the fuel injection system is tuned.

So is it worth the money? That depends on what money is worth to you and what kind of experience you want from your Miata. Do not look at modifications to your car in a way like how much X can I get for as little $. The Miata is not that kind of car. Think of your modifying experience as an emotional one that changes the character of your car and how you interact with it when driving. What type of experience you want to have when you drive your car will dictate whether or not IRTBs are right for you.
 

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freedomgli said:
What goes best with IRTBs: RoadsterJDM.net, for one. Or how about a 2.0L stroker motor made of forged crank, forged connecting rods, forged high-compression (greater than or equal to 11:1) pistons, upgraded main bearing support, better oiling (perhaps better baffle tray, true high volume pump, Accusump, or dry sump), ARP hardware throughout, gasket matched everything, fully built head including larger titanium valves, solid lifters with shim under bucket design, titanium valve keepers, fully radiused valve seats, high performance valve springs, big cams, adjustable cam gears, high-strength timing belt, dual feed fuel rail, bigger primary injectors mounted outside the throttle plates, quality tuned header and exhaust system sans cat (otherwise you'll destroy it during tuning when running rich), thermal and friction reduicing coatings throughout, everything lightened, balanced, and blueprinted, a whole bunch of other secret pro engine builder tricks, killer standalone engine management, 100 hours dyno time with the assistance of a professional tuner, etc.
Keep in mind the motor alone built with all that, assuming you do none of the work, is in the $8-10k neighborhood, and that's assuming you put the thing in yourself...
 

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So is it necessary to build up the engine like that to get good benefits from the IRTB setup.
 

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Yes and no. All engines need air and fuel to make power. Fuel is no problem (since you can always add bigger fuel pumps, injectors, etc.) but air is - this is why people add forced induction. If you're going to stay naturally aspirated and still want to make power than you need to pump more air - more engine displacement, higher revs, and/or more efficient breathing. Look at the entire system from the environment from which the car inducts air to the exhaust system that spits it back out and everything in between. To get any reasonably decent performance results from IRTB (despite what Jimmy at Fuji Racing might try to say otherwise- remember, he's a salesman first and foremost) you will need a built head with big cams and lots of port work, stiffer valve springs to rev higher and prevent float, and standalone engine management. At some rpm level the stock hydraulic lifters, ignition system, bottom end and other components will become a problem. Obviously, each year is a little different and so not all advice can be applied equally to all Miata.
 

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freedomgli said:
Obviously, each year is a little different and so not all advice can be applied equally to all Miata.
What you're saying though basically applies. The Miata's BP and B6 engines more or less have fixed capabilities for flow, compression, rev limits (pre-programmed and real limits before things start going to crap), etc. Those limits do not really allow for IRTB's to have great potential with the engine in stock internal form.

An engine is an air pump, and the way to make it more powerful is to get more air through it per unit time. The only way to do that is find a way for it to process more air (improvments in port matching, machining, etc.), force air into it (turbos/SC's), or spin the heck out of it (higher rev limits and necessary reinforcements needed to achieve said revs).

EDIT: Alternatively, as pointed out, the other solution is to allow more air as a baseline (larger displacement).
 

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Hmmm, sounds like I'll be keeping my SC for awhile while I build up a spare motor.
 

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i don't think i am in over my head. maybe i just wasn't clear on my question. i guess i wanted to know what the gains would be with a stock motor that has a header and exhaust (no cat hehehehe :D ) i have a 97 with a JR header and a RB single tip exhaust. i also have a J&S timing retard computer but the car is no longer SCed so it just sits there and looks pretty.

so since you are so full of information and since this is a new forum why not rant about your experiences with IRTBs so all of us people that are 'in over our heads' can learn rather then searching through TONS of threads on miata.net?

and what your saying about modding the car and the experience? i am not a ricer but im also not rich. i can't decide on forced or NA so i am asking around.
 

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To put it simply, IRTBs aren't things that you can just bolt on and get a guaranteed specific hp improvement like you can with an FMII kit.
 

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soooo i hear that a stock miata with a MS can make an added 20HP..... (yes, tuned) what do you think the gains would be with IRTBs and a MS with JR header, and no cat and RB exhaust? since i wasn't asking what just bolting on a IRTB setup would make i thought i would elaberate.
 

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touge miata said:
soooo i hear that a stock miata with a MS can make an added 20HP..... (yes, tuned) what do you think the gains would be with IRTBs and a MS with JR header, and no cat and RB exhaust? since i wasn't asking what just bolting on a IRTB setup would make i thought i would elaberate.
It is not uncommon for a well-tuned standalone ECU to add 10-20rwhp to a mostly stock car. Not just the MS.
 

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touge miata said:
since i wasn't asking what just bolting on a IRTB setup would make i thought i would elaberate.
Your car might as well be stock since adding just an exhaust and header alone to a '97 BP motor isn't really the type of mod that allows you to utilize the extra breathing capacity of the IRTBs. My educated guess would be that 4 properly tuned throttles might add at most 20-25 whp to a BP with standalone, JR header, test pipe, and RB exhaust, most of which is due to leaning out the fuel mixture with the standalone. To make real hp numbers with 4 throttles you need to rev high, do lots of head work, and the necessary bottom end mods to support it. Like in life, there are no free lunches when it comes to N/A tuning.
 

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Bryan said:
touge miata said:
soooo i hear that a stock miata with a MS can make an added 20HP..... (yes, tuned) what do you think the gains would be with IRTBs and a MS with JR header, and no cat and RB exhaust? since i wasn't asking what just bolting on a IRTB setup would make i thought i would elaberate.
It is not uncommon for a well-tuned standalone ECU to add 10-20rwhp to a mostly stock car. Not just the MS.
yeah i didn't mean to make it sound like just the MS ECU could do it... i guess i was thinking of this post someone made about their MS...


Freedomgli,

how much do you need to build the bottom for high revs? can you get away with just head work (ie: springs and retainers?) and reach maybe 8 or 9k?
 
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