IRTB goodies

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Re: IRTB goodies

Postby twmboy » Wed Feb 13, 2008 12:37 am

no matter what itb setup you get ( fuji (oer), jenvey, twm ) you shouldn't have to tune it much at all. the stuff I listed above was based off of jimmy ( fuji-racing's ), miata. a lot of people think that with itb's they'll be able to get a decent bump in power ( ie. 15-25hp ). in actuality this is very optimistic with low compression pistons. jimmy's put in about $4000 (msrp) into his motor, but he'll never admit that. if you're aiming for a fun engine with about 140-150 hp, I'd get a '01 bottom end, shave a tiny bit off a 99-00 head and get a megasquirt. that should run you a bit over $2000, and still be very competitive. spend your money on a good tune instead of going to itb's. it'll be worth more in the long run. I was at huffaker today and witnessed the result of a bad tune on one of jim russells new engines (http://www.jimrussellusa.com/index.php? ... &Itemid=57), and it wasn't pretty.
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Re: IRTB goodies

Postby Caoboy » Wed Feb 13, 2008 12:51 am

greasem0nkey86 wrote:wait for ed to come back from learning how to drive

he'll chime in on the ffsc, and he's not happy about it
:lol:


uh oh, i was planning on one for the next car
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Re: IRTB goodies

Postby greasem0nkey86 » Wed Feb 13, 2008 1:06 am

i dont think its the sc thats bugging him, more of the electronics
oh and that spark plug that somehow got fuxored
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Re: IRTB goodies

Postby LastManStanding » Wed Feb 13, 2008 1:09 am

twmboy wrote:no matter what itb setup you get ( fuji (oer), jenvey, twm ) you shouldn't have to tune it much at all.

Adding itb's drastically shortens the length of the intake shoving the resonant frequency of the intake into the far upper range. You wouldn't need a drastic tune, but you would need a real tune and a real engine management system or you won't see any real gains (other than throttle response). Like you said, don't expect too much power gained from itbs alone. To make the most out of it you would need to do some internal work; compression, cams, higher redline.
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Re: IRTB goodies

Postby twmboy » Wed Feb 13, 2008 1:33 am

LastManStanding wrote:
twmboy wrote:no matter what itb setup you get ( fuji (oer), jenvey, twm ) you shouldn't have to tune it much at all.

Adding itb's drastically shortens the length of the intake shoving the resonant frequency of the intake into the far upper range. You wouldn't need a drastic tune, but you would need a real tune and a real engine management system or you won't see any real gains (other than throttle response). Like you said, don't expect too much power gained from itbs alone. To make the most out of it you would need to do some internal work; compression, cams, higher redline.


exactly. I like cr.net and all but apparently most of them lack this very basic common sense. itb's were designed for top end power out of a "built" motor. itb's on a stock motor is just throwing money away. throttle response on a low powered car will be just that... throttle response on a low powered car! throttle response alone doesn't make up for hp. throttle response plus a fully built N/A motor is another story. remember, jimmy advertises that he did a 1:34 at laguna ( or some number like that ), what he doesn't advertise is that he was 4 seconds off a higher hp miata.
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Re: IRTB goodies

Postby Ken P » Wed Feb 13, 2008 8:49 am

ok, the no need to retune stuff is good to know. So if i do decide to take the ITB route, i will be running a 94 bottom end (higher comp pistons, maybe 11:1? with forged rods), 99 head with mild valve cut, definitely a MS, and In and Outs. would i be able to run the factory size injectors with this setup, or am i better off with a higher flowing one? im only looking to get about 140-ish to the wheel but with useble midrange torque.
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Re: IRTB goodies

Postby Ken P » Wed Feb 13, 2008 8:52 am

[quote="greasem0nkey86"]only thing you need to worrry about is syncing the throttle bodies and checking the linkage

no need to retune if you have a good setup

didnt you have to sync your bike throttle bodies? (No, theyre not carbs. newer bikes are self diagnosising.)

you can go irtbs or sc for what you stated
OR a small turbo setup (No, this is a discussion about ITB's. stay on topic)
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Re: IRTB goodies

Postby thepass » Wed Feb 13, 2008 11:12 am

My bike has carbs, just had them re-sync'd. Haven't done that myself yet but it's not supposed to be a big deal, and is probably even easier on say, a miata w/ itb's since they are sitting in teh middle of the engine bay and you don't have to remove a thing to get to them.

Perhaps I was optmistic about the 'easy' 145 whp with itb statement I made. I too was referring to Fuji's car. However, I think that redoing the head with the necessary parts to rev higher, bumping the compression (would a head shave be enough for a good difference or would you need to go pistons?) and itb's plus of course, header + exhaust which many already have, would be a pretty damn quick motor... and the real important thing is that it'd be a very very responsive motor as well which is what I was saying is the reason for going this route even though hp vs. dollar is less than going w/ boost.
Really, that's not all THAT much... yea you could dent the credit card alot if you pay for tons of labor, but I've put motors together before, if you buy the necessary parts for the head (titanium valves, stiffer springs, etc.) you can put all that in yourself, drop the head off to get it shaved, pop the motor in the car and install the itb's yourself. Then it's just a matter of going to the dyno a few times to tune.

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Re: IRTB goodies

Postby Papa Smurf » Wed Feb 13, 2008 11:49 am

oh my bazagas! :shock:
NCR window decals! $4
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Re: IRTB goodies

Postby nitewing117 » Wed Feb 13, 2008 11:56 am

I saw that huge CF...balloon looking thing and knew it had to be a honda thing right away. The s2k has an intake like that; this huge CF..thing. Too bad it costs like a grand.
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Re: IRTB goodies

Postby thepass » Wed Feb 13, 2008 12:04 pm

I can make one of those 'ballon things'... Fiberglass or CF, to form-fit any application needed, it's just a matter of shaping it out of foam and test-fitting first. Fiberglass would be less $$ since CF is ~$60-$70 / yard right now :D

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Re: IRTB goodies

Postby nitewing117 » Wed Feb 13, 2008 12:08 pm

same :D Does anyone know what the benefits of one of those would be for?
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Re: IRTB goodies

Postby Ken P » Wed Feb 13, 2008 12:30 pm

larger available air volume. its like sucking air through bong vs a joint.
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Re: IRTB goodies

Postby twmboy » Wed Feb 13, 2008 1:22 pm

thepass wrote:My bike has carbs, just had them re-sync'd. Haven't done that myself yet but it's not supposed to be a big deal, and is probably even easier on say, a miata w/ itb's since they are sitting in teh middle of the engine bay and you don't have to remove a thing to get to them.

Perhaps I was optmistic about the 'easy' 145 whp with itb statement I made. I too was referring to Fuji's car. However, I think that redoing the head with the necessary parts to rev higher, bumping the compression (would a head shave be enough for a good difference or would you need to go pistons?) and itb's plus of course, header + exhaust which many already have, would be a pretty damn quick motor... and the real important thing is that it'd be a very very responsive motor as well which is what I was saying is the reason for going this route even though hp vs. dollar is less than going w/ boost.
Really, that's not all THAT much... yea you could dent the credit card alot if you pay for tons of labor, but I've put motors together before, if you buy the necessary parts for the head (titanium valves, stiffer springs, etc.) you can put all that in yourself, drop the head off to get it shaved, pop the motor in the car and install the itb's yourself. Then it's just a matter of going to the dyno a few times to tune.

-Ryan


assuming you have a 94 engine (8.8:1 pistons), shave a bit off the head (maybe get half a compression point if your engine builder feels safe with that), you're still only about 9.3:1 compression. putting on stiffer valve springs and titanium valves willl allow you to rev higher, but then your weak point will become the stock rods (which were not designed for higher revs). you could hit 8000 every once in a while and be fine, but if you plan on using it for a track set-up, I hope you have AAA.

don't get me wrong, 145 whp isn't bad for a miata motor, but there are cheaper ways to do it ( and not have to go FI ). one way to think of building a motor is like this. you put your boxers on before you put your pants. not the other way around.

if you add it up:

$3000 for stage 3 cams, megasquirt, and OER( "fuji-racing") throttles. (assuming you already have a header/exhaust)
+$500 for a 99-00 head
+$500 for a tune (probably more if they know how to tune properly)
+$100 for filters
=$4100 before tax. completely gut your car with this setup and maybe you can run a 13.9 with a fast reaction time.

on the other hand....

$499 for 11:1 wiseco pistons at http://www.racingmazda.com/bseries-enginerebuilding.htm
+$299 for cat rods at http://www.949racing.com/index.asp?Page ... &ProdID=73
+$625 for stage 3 cams at http://www.integralcams.com/miata.htm
+$500 for 99-00 head on ebay
+$695 for megasquirt at http://www.diyautotune.com
+$500 for tune (assuming it'd take about 3 hours)
+$1000 for labor (unless you can do it yourself)
=$4119 before tax. gut your car out with this setup and you'll embarrass the guy who paid the same for "throttle response"

have you noticed how many people sell their OER throttle setup? it's because they realized they paid a shit ton for an under powered car with a noise maker for "throttle response". don't get me wrong. I love itb's, but most people who love itb's more than a built motor, haven't experienced a properly built motor ( or an under powered motor with itb's ).
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Re: IRTB goodies

Postby Ken P » Wed Feb 13, 2008 3:12 pm

Im stickying this. a lot of good information on here. thanks joey.
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Re: IRTB goodies

Postby LastManStanding » Wed Feb 13, 2008 8:25 pm

Gee Oh Dee wrote:Would i be able to run the factory size injectors with this setup, or am i better off with a higher flowing one? im only looking to get about 140-ish to the wheel but with useble midrange torque.

It's pretty hard to get into a range that you would need new injectors. You do gain some power by removing some intake restriction, but you arn't really putting more air in the engine. Revving higher does require more fuel though. If you get past 11K, that's about a 30% gain in fuel needed, at which point you might think about upgrading. You could always just bump fuel pressure a couple psi and avoid the whole issue.
Don't expect much midrange. If you do this you're putting your stock in the high revs. Shorter runners favor the high rpms. Itb's are pretty damn short. To give you an idea of how much intake length effects power you can read the below pages which came out of my mazda service manual. I'm not too familiar with miata intakes so I don't know if it's variable, but I've got 1 butterfly valve in mine and you can feel the boost right when it hits. Some really nice itb set ups have those variable stacks, which are sweet, but I'd imagine they are incredibly expensive to make/tune.

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Re: IRTB goodies

Postby Ken P » Wed Feb 13, 2008 10:15 pm

from what i understand, the itb characteristics is very good throttle response, and better midrange torque. i also understand that shorter velocity stacks are for quicker acceleration while the longer stacks are for better top speed. so i would imagine that if you can tune the setup to your specific driving needs. am i mistaken in assuming that this is the case?

ps: this is turning into a pretty good discussion so im moving all the pictures to another thread.
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Re: IRTB goodies

Postby greasem0nkey86 » Wed Feb 13, 2008 11:02 pm

Gee Oh Dee wrote:
didnt you have to sync your bike throttle bodies? (No, theyre not carbs. newer bikes are self diagnosising.)

you can go irtbs or sc for what you stated
OR a small turbo setup (No, this is a discussion about ITB's. stay on topic)



i said throttle bodies not carbs, and if they're self diagnosising, then why did my friends 04' ninja didnt self diagnose? had to send it into the shop to do it

and it was just a suggestion

joey, any comments on rod length, something about the ratio of piston and rod(forgot the exact terms), not being suited for sustained high rpms, because of undesired rod length i believe?
not sure if you remember, it was a thread that started on cr.net, small while ago and i think you participated on the discussion

oh and any reason you specified the 949 rods?
was looking at FM's carrillo A beams, i mean, since we're building a N/A motor with good throttle response, isnt a lighter drivetrain desired?
seems like the A beams fit the bill, light, and not as strong as the H beams, but we wont be exerting extra pressure from boost
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Re: IRTB goodies

Postby Ken P » Thu Feb 14, 2008 12:06 am

i believe the term you are looking for is "stroke".
as for the bike's throttle bodies (i used carbs as a point of comparison, not insinuating that you dont know the difference), my gixxer's are self diagnosising, but that doesnt mean they resync themselves. that would be self adjusting. self diagnoising only allows the ecu to determine which cylinder(s) is running lean or rich and vary the pulses for the other ones to even out the combustion. the bike will start to run inconsistently untill you resync them. so in theory they dont NEED to be resynched, but its usually a good idea to do that at maitenance intervals.
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Re: IRTB goodies

Postby LastManStanding » Thu Feb 14, 2008 12:48 am

Gee Oh Dee wrote:From what i understand, the itb characteristics is very good throttle response, and better midrange torque. i also understand that shorter velocity stacks are for quicker acceleration while the longer stacks are for better top speed.

Top speed, more than anything, is a function of gearing, redline, and whether or not you have the power to make it to redline.

For example; The mx recieved a detuned version of the 1.6 miata moter. Take the miata motor, subtract an oil channel, reroute the coolant, put a distributor on the exhaust cam, retard the engine a bit, and that's what I have. On top of that they decided to make me even slower by giving me longer gears. Even with the power loss though I can hit 120mph without even flooring it. The car redlines at a little over 130mph. From what I've heard that's pretty much out of reach for the 1.6 miatas.

You are able to tune the stacks for certain areas. The basic idea behind them is you want as much air velocity with the least amount of restriction. Unfortunately these are conflicting terms; for a given flow rate velocity increases as a runner becomes narrower (or longer), but resistance rises. This can all be shown by Helmholtz's equations. As it relates to cars: Low rpms have little flow, thus favor long narrow intakes. High rpms need more flow, or short fat intakes. This same idea is mirrored in exhausts. Hondas improve their efficiency by catering to the low rpm with those laughably small stock exhaust systems. With itb's you can have decent velocity stacks to maintain your low end, but overall you can see their length doesn't compare with the length of a stock intake. Not that you should care though; with an NA car it's all about the high end =b
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Re: IRTB goodies

Postby Savington » Thu Mar 13, 2008 12:34 am

In a 4-stroke, 4-cylinder motor, only one cylinder will ever be attempting to fill itself with air at any given time. Why the hell would you want to fill that cylinder through a 40mm or a 45mm TB vs. a 60mm+ TB? The gains from ITBs can be matched with a well-ported intake manifold, you don't need to spend a shitload of money on engine management, internals, and headwork to make a new intake manifold work well, and when you decide that throttle response is overrated and you're tired of every new Accord and Odyssey mopping the floor with you off every stoplight, you can bolt a turbo to an intake manifold like you should have done in the first place.

And Jimmy is the biggest moron of them all, the KING of shitty dyno charts. Anyone else remember the "FUJI RACING 175WHP ON IRRRRRRRRRRRRRRTBS AND STOCK MOTOR" thread on CR.net? Anyone else remember his Fuji header vs. RB header chart? (the one where he brags about how good his header is, and then posts a chart where the RB header makes 2lb.ft more than his header does at every RPM)

If you guys really want a nice, NA build, take a look at Bob. Professionally-assembled motor, 10:1 pistons, proper fuel management, nice headwork, and a STOCK INTAKE MANIFOLD. Then take a look at my car, and know that I have 80whp on Bob and I spent half of what he did.

You guys REALLY ready to sacrifice 80whp and five thousand dollars for throttle response?
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Re: IRTB goodies

Postby Ken P » Thu Mar 13, 2008 12:49 am

naaaaawwwwwwwwwwwwsss
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Re: IRTB goodies

Postby Popstoy » Mon Mar 24, 2008 3:04 pm

Can I butt in, while I've never had IRTB's, I have had many multible carburated on individual runners, and they're a pain in the ass, they require constant balancing, particularly if you require maximum performance, they won't idle worth a damn, even worse with a built motor, makes the engine very finicky to atmospheric conditions, like temp, humidity, altitude. On a computer controled engine like the Miata, where the a/f ratio is controled by sensors, and adjusted after the fact by the 02 sensor, which is an average of all 4 cyclinders, I sure wouldn't want different cyclinders running at different a/f ratio's, and that's what you'd get unless they're kept in perfect balance. Then you've got the problem of how to filter the incoming air. Sure you could put individual filters on them, or build something, so that they all draw air from a common soarse, like a huge airbox, as used on most motorcycles. You know, there are many ways to improve throttle responce, and power, dollar for dollar, irtb's have to be one of the more exspensive, least productive, and high maintance way's to go. Bob
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Re: IRTB goodies

Postby Ken P » Mon Mar 24, 2008 3:26 pm

hey pops welcome! fwiw, sometimes its not about cost efficientcy.
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Re: IRTB goodies

Postby Popstoy » Mon Mar 24, 2008 3:36 pm

Ken, You know me, well enough to know that cost is the last thing I consider. If they provided a reliable, trouble free, improvement, I'd already have them. Bob

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