Optics

Looking for a few opinions on this setup. Anyone have any performance comparisons between running the fujiracing complete IRTB kit from http://www.fuji-racing.com/fujiracing_005.htm versus the IDA TB's from tweakit at http://www.tweakit.net/shop/product_...7e95371a3bc598 using their IDA webber 6 port manifold http://www.tweakit.net/shop/product_...7e95371a3bc598 run under a microtech lt10s in a large streetport 6 port s5 block?

Would tuning be workable using only the 4 injectors integrated into the TB or would I have to have bungs welded into the LIM for tuning purposes? Also if staying NA there would be no reason to get the plenum for the tweakit TB's shown at http://www.tweakit.net/shop/product_...7e95371a3bc598 is there? If i'm correct that is simply to allow turbo applications a quick gulp of air when you romp on the throttle untill the turbo can spool up and give adiquate air for the tb's... I'm leaning heavily towards the tweakit tb's in a 55m - 50mm taper and IDA webber manifold in 50mm with six port sleves left in but not functional and pineapple racing inserts to help out with flow. The 4 550cc injectors I have should be lots of fuel for this setup but i'm wondering how i would tune this with a lt10s since I dont see any provisions made to mount a map sensor, I guess something custom would have to be plumbed in.

Other than that it looks fairly plug and play, and performance should be a nice increase over the ported s4 manifolds i'm running now. If anyone has an alternative setup that they think might produce a bit better power please let me know your opinions as i havent ordered anything yet. The major advantage of this system in my eyes is that it will remove the stock LIM and allow plenty of space to fit a turbo in the future using standard manifolds available for the FC. Also please not that I'm not willing to custom make an intake manifold, but really like the look / performance of ITB's... I am not a welder nor am I a mathamatician so calulating custom intake lengths and welding / bending a manifold is not a route that I will be going. If anyone knows of a custom manifold to allow space for a turbo while mounting ITB's up top and fitting under the hood besides the two above I'd love to hear about it so that I can explore all the options available here.

Also looking into the TWM induction TB's but I have yet to find one with the tapered aspect and from what I can understand that is a fairly signifigant feature and should increase intake velocity considerably... sorry for the long post, but want to get as much infomation as I can think of out there to get usefull feedback in return. Thanks for the help with this project.

More info on ITBs can be found in the following threads i've come across, but none have really shown a step by step bolt in / tune that i've been able to find... any refereance to such a thread would be greatly appreciated!
https://www.rx7club.com/rotary-car-performance-77/what-can-you-tell-me-about-itbs-na-13b-620007/
https://www.rx7club.com/showthread.p...highlight=ITBs
https://www.rx7club.com/showthread.p...highlight=ITBs
https://www.rx7club.com/showthread.p...highlight=ITBs
some pics at https://www.rx7club.com/showthread.p...highlight=ITBs

EDIT: I've just tried the links to the tweakit site and they dont work... all parts can be found on www.tweakit.net, and navigating to the rotary performance ---> intake manifolds and
----> throttle bodies

Black91n/a

Well the main difference between the Fuji kit and others will be the vacuum manifold for the brakes, the thottle cable setup and some other minor fittment issues, and the intake length. Here's a good thread about that:

https://www.rx7club.com/showthread.p...=intake+design

You basically have 3 options, downdraft, the Fuji, or sidedraft with the stock LIM. Each will have a slightly different powerband. For a street car the sidedraft is probably better.

Now, for a plenum, you want filtered air, and you don't want those filters that slip right over the air horns. You can do a cold air intake with a plenum. The larger the better. There's a guy who did a bunch of testing on a Miata and showed improvements by going with a large plenum (Chris Chan IIRC).

anewconvert

iTrader: (1)

Jimmy said he has yet to sell his kit to anyone in the states. (rotary kit) He is in the process of building a rotary miata that will have some mild porting, full exhaust and his IRTB kit. If I could come up with the cash that is the route I would go, for two reasons:

1) Jimmy has a fantastic reputation in the miata community for making a top notch product and supporting it completely

2) Its a full kit with everything yo would need to get running (if you purchased a microtech through him or had your own standalone) There is no hunting for parts, everything is there.



There is a lot of argument over whether or not a plenum is a good idea. The sock filters have a bad habit of distrubing airflow into the airhorns, but Jimmy seems to dislike a plenum them for whatever reason and argues against them on the miata forums.


BC

veedubbed

Port length and shape will have a huge effect on what works best. What works best on Miata's probably isn't what's best for a 13B. Not that I'm saying it wouldn't, but with a GOOD ITB setup, everything needs to be turned for the exact motor it is going on.

Optics

Thanks for that extremely (long!) informative link black91n/a! Just read through it but honestly will have to read through it once more before i'm comfortable with all the information presented in it. As for the side draft option using the stock LIM... that is not a route that I want to pursue. Like I said i'd like the additional clearance provided by an aftermarket LIM to simplify any future turbo plans that may develop. I will dig around and see if i can find some pictures of my ports to post and maybe give a bit better of an idea regarding the exact intake that would fit my application the best. I'm really happy to hear all of this positive feedback on the fuji racing kit, I suppose I will have to call him to get a bit more information regarding the kit as his webpage is rather limited at the moment. As for the throttle bodies themselves I still think that the tapered nature of the tweakit tb's would be a significant advantage over a straight through system. Thanks for the additional information on the plenum, I was under the impression it would hinder an NA setup due to reduced airflow. But if it would make only a marginal difference it would be worth the extra cost for sure as it would make future upgrades much easier and allow me to re-use my cold air box (with some revised piping). Independent of intake length, and looking strictly at hookups... I dont see any thing extra that I would need going with the tweakit kit over the fuji racing kit... as both are essentially bolt on and the tweakit kit can be outfitted with a vacume source for $26 AUD. Thanks for the info so far!

Black91n/a

The reasons cited for wanting the large plenum was to improve throttle response on tip in. It may not (and probably isn't) better than no filters for power, but if you're going to be having a filter, I beleive it's the way to go as the air has a chance to calm down before going into the TB, and there's that option of COLD air, which is valuable.

Optics

Thanks black91n/a, that does seem to make sense that a filter inches from the throttle butterfly would lead to a rather turbulent (and unpredictable) air stream across them. It sounds to me like this situation could make tuneing quite difficult and lead to headachs down the road. Since I will be streeting this car regularly I will be running some sort of filter, and it sounds like a plenum with a cold air box & re-using my K&N will be the route to take.

From the website it doesnt appear that the Fuji-racing kit uses a plenum and I dont see any options listed to outfit one, although I will ask when I call. The tweakit setup is looking more and more appealing...

coldfire

iTrader: (1)

sounds like an interesting project.
if you do go through with this to completion can you please get on a dyno? i am very interested in what sort of results this gives, and what the powerband changes and gains are like. there's not too much result information on this.
unfortunately it comes down to a lot of physics and math to get things just right i think. matching intake, porting, and exhaust there's a lot of things to consider and i think it's near impossible to get it perfect unless you are an R&D company or race team with a big budget. just throwing a bunch of parts together might gain you some power and what not but it won't be optimal.

Optics

Thanks for the encouragement coldfire,

As for the results I don't know how much can be learned from this project since I don't have a base dyno graph for this engine as it is new. All I can really hope for is good numbers. I just talked with Jimmy at fuji racing, he sounds like a really great guy to deal with. His kit does sound rather limited however. It consists of a carburetor LIM (didn't give a brand), an adapter plate, and a set of OER TB's with a single rail for 2 fuel injectors. There is no plenum, an unknown runner length, no provisions for a map sensor, factory throttle cable made to work using a modified alternator bracket from your engine and a 5 bolt reference TPS. While the kit sounds like it is developing nicely and there will be several improvements down the line it doesnt sound to me like it is completed (or justifies the current cost) at the moment.

I also spoke with Brian from Japan2LA (a forum vendor) and he carries a LIM for a 4 port which he modifies to fit a 6 port block similar to his modification of a TII LIM for the 6 port. This would make for a bolt on application and plenty of clearance for a turbo using any s4/5 aftermarket manifold. This sounds like an appealing option... but runs at $250.00 for the manifold and $100.00 for modification service. The Webber IDA LIM for the 6 port runs just over $200 from most locations and also bolts the TB's up top. Maybe a bit of a UIM could be fabricated to adjust runner lengths to optimum before bolting to the TB's.

The tweakit TB's with the Webber IDA LIM are still sounding like the best performers to me. With 4 injector holes, vacuum nipple, tapered bore design and a plenum that bolts right on they seem like a great setup. This kit also is designed to fit under the stock hood. Weight savings should be fairly large with this kit versus the stock intake tract, and throttle response should be vastly improved. Getting close to ordering this... bit more research to do.

anewconvert

iTrader: (1)

Ok, Im going to try for the 3rd time to post in this thread. Everytime I post it doesnt put it up there.

Jimmy has a fantastic reputation in the miata community for not only supporting his product, but providing a complete product. He uses a webber LIM to mount the throttle bodies on. If you are worried about his knowledge of rotaries he used to work with Kilo racing (Jesus Padilla). He has, on many occasions on miata.net, spoken against using a plenum with ITBs. I dont remember his reasoning, but thats the reason behind not having one.


BC

Black91n/a

http://www.cardomain.com/ride/505452/4

http://forum.miata.net/vb/showthread.php?t=170175

I was wrong, it's Chris Chu. There's some discussion about plenums there. He states that it's to get better flow than those over the horn filters and go big for throttle response. It also helps keep noise down for streetability.

coldfire

iTrader: (1)

maybe fabricating your own UIM would be the best way to go? that way you can design your own runner length based on what you need, and you can even get some calculations done for runner length.
all these LIMs seem to be designed for carburetor usage, and i think just putting the TBs directly on them the runner length would be too short to get a full powerband, unless you are building a higher revving engine than stock.
just a thought.

Optics

I definitely agree with you on the custom UIM advantages coldfire. It wouldnt take much in the way of fabrication skills and i could source out the job to a local exhaust shop for fairly cheep I'm sure. All thats really needed is a bit of bending and welding two flanges onto 2 pieces of aluminum pipe. They couldn't charge me more than a couple hundred dollars for that and based on the link earlier by black91na their could be significant gains from the correct intake length. Will have to start crunching some numbers to find out the lengths I'd need.

As far as the plenum thanks again for those links! very informative, and it seems that there are many advantages to going with a plenum and few disadvantages. Since this setup is mainly geared towards throttle response I think that the cold air charge and less turbulent air would add alot to the setup.

Current plan as it stands is webber LIM bolted to a custom UIM bolted to a tweakit ITB with a tweakit plenum and some custom intake piping to get back to a cold air source with a K & N cone filter on it. Throttle response sounds like it will be great and peak power should see a nice gain if I get the UIM track length fairly close to where it needs to be.

Need to figure out the optimum UIM length with the port durations that I have now. Found those pictures of my ports and if this works like I think that it does they should be below, lol.

Edit: pictures worked, and re: the exhaust port I have a set of tapered sleeves in there to ease the transition to the exhaust and reduce max size a little bit.

coldfire

iTrader: (1)

wow that auxiliary port looks quite large. there hasn't been too many people who have posted results of big bridged aux ports like that, i'm interested to see what that will give. the more proven route is to just bridge the secondary.
did you leave the primary port fairly stock or go aggressive on that too?

that exhaust port looks quite large also. it's interesting you mention putting a sleeve in there. a lot of people think the primary function of the stock exhaust diffuser was to reduce noise but in fact it was to smooth out the exhaust flow to maintain proper velocity as the rotor traveled across the port.

Black91n/a

http://www.yawpower.com/dec2004.html

That's one option, but if you use a manifold like that with 6 ports, the flow won't be too smooth.

Notice they use a plenum?

Sideways7

iTrader: (7)

So you just bridge the aux? Why not the secondary as well? You will still get the same side effects from the bridge, but will have more power potential I would think.

Optics

Primary's are pretty aggressive as well coldfire. Very similar to the porting of the primarys on the yaw power setup linked by 91na for reference sake. Thanks for that link by the way... I LOVE that star race cars intake manifold that they used! I goggled as hard as I could but to no avail... anyone know where to find some contact information for that company? If they have a 6 port manifold I would love to hear about it as they look like their top notch quality.

Thats also quite a large plenum that their running, and its really interesting how they fed it with two separate intake tubes / filters. Are their any advantages to this route versus a single larger filter in a similar setup cold air box? I'd think that if anything it would just increase the surface of the cold air exposed to the hot underhood temperatures and that you'd be better off with one large tube than two small ones... but maybe the small tubes keep intake velocity higher? If anyone knows why they ran this setup versus one large tube I'd love to hear input!

Black91n/a

There may not be enough underhood height to get a larger duct in, and there may not be a larger duct available. It looks like 4" high temp brake duct, and I think that's as big as it gets. I wouldn't really think there'd be any particular advantage one way or the other.

The manifold would be from one of these: http://www.starmazda.com/cars.htm

They only used the 4 port blocks, so there wouldn't be any 6 port manifolds.

Sideways7

iTrader: (7)

I saw some setup a while back that was interesting. It was on a half-pp NA 20b engine or something ridiculous like that. Anyway, he ran the air inlets into a costom made air box (plenum?) that had a K&N filter on it. If done properly, you could actually do this and utilize the stock TII hood scoop for a CAI.
This is my dream if I ever go ITB's, BTW.

Aaron Cake

iTrader: (1)

Continue the bridge down so that it forms a real half bridge. Then bridge the primaries as well. You'll be much happier.

Optics

I love the idea of the TII hood for CIA, never considered that setup before... seems like it would be a very efficient system. You could keep plumbing to a minimum and get some very cool air straight into your airbox with the additional benefit of a ram-air effect at higher speeds.

As far as the porting goes engine is already done and assembled so there wont be any alterations in that arena.

Thanks for the great tips so far, getting some great ideas and products listed... its too bad that star race cars doesn't make 6 port manifolds as their product looks like the best I've seen so far. I just talked to someone with star race cars and they are developing a 6 port manifold but its still in the early phases for a project car. Probably wont be ready for some time yet. Unless something better presents itself in the next week or so it looks like I'll be going with the Webber IDA manifold.

SonicRaT

iTrader: (6)

I use a weber 6port manifold and a one-off TB similar to TWM, it's tapered from 55 to ~52mm or so. I've got an RB spacer between the manifold and TB, then I've got two velocity stacks built into my upper plenum/intake duct. I used this setup for a while as N/a while waiting for parts to arrive and it worked out pretty well on a stock block. It was a torqueless wonder though prior to playing around with spacing and stacks. Now it's got a turbo plugged into the mix, and it works quite well. My injector setup is very similar to stock. Two in the block on the housings still (idle is a million times easier to deal with than running them all in the TB), with two in the TB.

Optics

Sounds like your right where I want to end up sonicrat. That RB spacer you refer to... is that the phenolic ones listed in their weber section? How many spacers did you use to get good torque while still NA? Did you retain the spacers when you went turbo? Also how did you develop your plenum... what was its size and shape, and how long of stacks did you run before mating to the plenum?

Thanks for chiming in, any pictures of your setup would be a bonus by the way .

SonicRaT

iTrader: (6)

I wish I had some pics of it assembled, I'll try to dig up what I can of the parts laying around off the car though. Yes, they're the phenolic (I couldn't think of that word and was in a hurry earlier). I used just one set of them which was roughly 1/2" with gaskets, it didn't make a drastic change while in N/A form as I was just using some short velocity stacks. I'd say it moved the powerband maybe 250rpm or so, but given my driving style it made up enough for where I normally tend to roll from. I still have them on in my turbo setup, I haven't really dialed that in much since shortly after I put it together and made two dyno days with it I moved away, and since a lot has been stolen from the vehicle. It's now in the process of being restored.

The plenum designs have veried. I've tried using an upper plenum that was simply two mandrel pent pipes forming a Y going to my intercooler, and this worked out well for daily driving and I didn't notice any issues with torque/etc. Though when I hit the dyno I wasn't getting nearly what I was hoping for, the top end just seemed to choke and gag, my spool was also pretty abbrassive and late. Rotaryshack sent me some pictures of some of their setups and I tried very hard to buy one from them, but I believe they got busy when we were discussing the setup so I ended up having one similarly made on my own. I have some details of the stack sizes as well as the plenum chamber size/inlet size, but I don't recall where they are. I believe the chamber was 4.25" with a 3" inlet, and the stacks were welded internally. This considerable helped cruise response and seemed to clean up my top-end considerably. I figured I would have lost some with the stacks acting as a restriction, however I think do to the better flow layout and transition between the two rotors there just a better flow characteristic. I went this route as I was hooked on my original 'hackjob' 6-port turbo and I absolutely wanted to keep my 6port engine block. Rather than going the way of Aaron and modifying intakes, I looked for what was already available and how to put what I was looking for together. It's kind of late but I'll see what I can find for you. Needless to say, I was extremely pleased with how everything turned out and I would really never go back and try anything else regarding manifold setups for getting a turbo on my 6port block.

coldfire

iTrader: (1)

another thing to look into for intake design, as if it weren't complicated enough already, is "shared" runners. if you look at the stock Mazda manifolds, the two primary intake runners have a shared intake, as do the two secondary runners. basically there is a path from one rotor port to the other rotor port. this is to take advantage of the pressure wave that is generated when one rotor closes over the port, and helps to push air back up the intake into the other rotor's port that is just opening. i hope that makes sense, it's not a very good explanation, haha.

in addition to this, you can also then have seperate throttle bodies for the primary and secondary ports, just like the stock manifold does. this allows you to have a delay on the secondary TB if you wish, keeping the secondary ports "closed" until a certain throttle percentage, which generates higher primary intake port velocity at lower engine speeds/loads.

i have not seen any intake manifolds that have "shared" runners to take advantage of the pressure wave effect. i think maybe the theory is a little too complicated to factor in, and it's also harder to fabricate a shared runner intake manifold. but i would love to see one designed. just more food for thought...