cgoldhill

Ive been reading alot of posts on ITB setups and have started to see some asking the question "Could i just use a plenum on a set of itb's and run the stock maf?". Well i'm going to attempt to answer that question.

The plan/project is to use a 1996 Miata 1.8l, install a set of gsx-r 1000 itb's on a cut stock manifold and then use a combo of the gsx-r 1000's original airbox and TWM's 4 cylinder itb plenum. This will allow me to use the stock fuel system. I will then use the stock maf and a regular cone filter set up. The itb setup will be complimented by the usual header, exhaust, exhintake cam, some ignition advance and such.

I know many of you say " why even try?" and my answer is because no one has really, atleast that I can find.

I understand that ill probably need to play around with the intake length as their needs to be a balance between when the throttle plates open and when the MAF registers airflow, relocation of vacuum hoses, etc. My main concerns/questions are this:

Could the car be tuned with a safc 2 installed onto the stock ecu with the car on a dyno? (Ive also been looking into an APEXi igniton timing controller)

How can i splice the itb TPS into the stock wiring harness and have the stock ECU still read the signal as it should?

As far as idle control goes, can i just relocate the original IAC/ICV or must it be directly connected to the manifold?

Again, as I said, I know many of you would say why not just megasquirt, but the fact is I want to do just to say i did it. I know i wont realize all the performance gains of the ITB set up but its a jumping off point for me when I'm rdy to change over to a full stand alone.

I'm a DIY kind of guy so heres what the cost is looking like:

ITB's - $50
Various hose, silicone couplers and such - $100
SAFC-2 - $200-$300
GSX-R air box - $40
TWM Plenum - $300
Velocity stacks - $100 (optional)
All the do over, band aids, beer, and odds and ends - $200
Dyno time - $500

That adds up to a complete kit and running car of about 1500-1700 bucks for everything. If it works I'd say thats not bad. when it was all said and done I could offer a couple of home brew kits. I just need some input. If it can be done I'm going to do a full write up. If I'm missing something, or you dont think i quite understand something, please feel free to inform me but pls dont bash me, I have a vision haha. Thanks guys!

epikeddie

You're not going to get the adjustability of a true stand-alone for sure. I guess it can be a start for you. Make sure the runner lengths are matched to your setup and figuring out how to incorporate the TPS signal to the stock ECU is going to be a REAL challenge lol.

You say you're a DIY guy and making a DIY kit is alright and proper at times. But honestly, the management is going to hurt you and it's not even worth bothering to try.

Look how many guys complained about the piggyback OER management. Even with the simple turn-dials....people still ditched them and went straight for MS.

I think your hardware can definitely be done and you should try it if you don't want to plunk down the cash for a pre-made setup i.e. Fuji Racing (OER) IRTBs.

But please stray from those S-AFC and other piggybacks. There's a reason why all the Honda ITB guys are doing stand alone, there's a reason why 97% of the guys running IRTBs here are doing the same, and there's a reason why Shaun Church (Church Automotive- tuning guru) told me the exact same thing.

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1993 Miata (NA6CE): Integral Stage 2 cams, MSPNP9093, Bride VIOS III, H&R Race springs, Tokico shocks, Konig Rewinds, Header, Midd-Tenn Headlights, Mazdaspeed Test Pipe, Back to stock exhaust

freedomgli

Honda guys are lucky because they have MAP sensors from the factory. The Miata is stuck with craptacular flapper door AFM or hot-wire MAF. I've never seen anyone make decent performance with an Apex'i SAFC on a Miata that couldn't be done better/easier/cheaper using a different tool. Mazdaspeed sold a kit in Japan for the B-spec that basically did what you are describing. However, I don't know all the details on how exactly it worked. AFAIK no one has done any chip tuning on the US spec 1996 ECU.

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freedomgli

http://clubroadster.net/forum/viewto...?p=61541#61541

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FooSchnickens

It could, but you might also want to take a look at the HKS unit that came out a little while back. It might be suited more towards your needs.

It shouldn't be that difficult, you just need to get the aftermarket TPS to output the same readings as the OEM TPS. Nothing a little fiddling can't fix.

This is probably going to be your toughest obstacle. The stock IAC feeds into the manifold just past the throttle body. With the ITBs you'll need to find a way to do the same for each cylinder. The way that the OER kit does it is probably the easiest way for you to do it as well. Grab a chuck of aluminum and machine out the area for a nice vacuum log then have it split off to four hoses which would then connect to each throttle body assembly.

You would probably have an easier time if tried out the system on a single throttle first. That way, you retain all the normal idle controls and don't have to worry about properly calibrating the aftermarket TPS. Just slide out the butterflies from the TBs you have and run them open inside your plenum.

Hope it all works out for you, it will be interesting to see the results.

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cgoldhill

This is great stuff guys, Thanks so much. As far as a piggyback, it really doesnt matter to me what is used, as long as its around the same lines of an SAFC2 as far as price and simplicity(generally speaking) and still allows me to use the stock ECU and dyno tune it without having to fly someone in from Japan. What is the name of the HKS system?

The iac valve situation seems fairly easy to overcome and I think i understand what your talking about. Do any companys offer this hunk'o aluminium pre-drilled out and such? I dont really have the resources to construct something like this myself.

Again thanks so much guys, it looks like my biggest obstacle will be finding a good tuning system that will fit my needs. Any more suggestions on that?

FooSchnickens

Thing is, by the time you get an SAFC or HKS unit you're about $200 shy of a MSPnP and well over the cost of a homebuilt Megasquirt setup.

MS is stupid easy to tune with and use yourself. It's also a great learning experience that gives you a great understanding of just how your engine does its thang.

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cgoldhill

I do realize that but Ive had bad experiences with standalones and wires, wiring diagrams, and paying other people to do work for me isnt really my thing haha. I own a 240sx with a swapped rb20det which is controlled by an apexi power fc and all its been is a nightmare. Stupid expensive to tune, stupid complicated, and just alot more trouble than its worth in my opinion.

The closest dyno I have to me that would actually want to touch a stand alone is like 2 hours away and they arent even an apexi dealer/apexi certified.

Not too long ago I went into my local tuner shop to ask some questions and only one guy in the shop had heard of megasquirt. The rest of them looked at me like I was going to try and sell them some crazy hentai porn. It was mainly a honda shop, there isnt alot of "variety" on the east coast which makes things difficult.

I dont want to make it more complicated then i have to as the car will be my daily and i need it in running condition as much as possible aside from the regular brakes, oil changes, and tune ups. My experience with things is the more complicated things are, the more things go wrong, and alot harder it is to diagnose problems.

By no means am i trying to bash your advice as it is very much appreciated nor am I being close minded or ignorant. Many may say that MSpnp is really easy; I'm sure it is and I could probably figure it out but i just cant afford to have the car down for long amounts of time while i try to figure things out.

Thanks again guys for everything and anymore advice is welcome.

cgoldhill

Btw found that Fuji racing offers an IAC block so it seems that problem is solved. Now on to the tuning issue and everything should be sorted out...

coupeloop

theres your problem. If you know any toyota specialist thats done 20 valve swaps, or just ITBs in general would for sure know what MS is.

but I've seen this done but on another car. My mechanic's daughter has a 86 gts running 20 valve throttle bodies, with a custom plenum built over it. using NO engine management whatsoever. intake pipe just leads to the AFM and filter. car drives fine with great response.

you may come in to the problem of running rich on the miata with just a piggyback, i had my ITBs with the HKS vpc and the there was not much room for adjustments.(though i may be wrong with how adjustable a SAFC is because i never dealt with one before)
I had clocked the VPC all the way to lean and it was still dumping too much fuel. with all the time which comes to making the manifold, and plenum you can save yourself a headache by just getting a full standalone.
when i had installed MSpnp, fired right up with the ITBs. and it was like day and night.
but of course you would still need a tune out of it if you want to see higher numbers

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Believe.

FooSchnickens

It's totally the opposite with MS. If you get the PnP, it's exactly that: Plug and Play. It literally took me 5 minutes to uninstall the stock ECU, wire up the TPS and IAT sensor, run the MAP vacuum line, plug in the MS to the STOCK, UNTOUCHED harness, flash the firmware, load the basemap, and start the car. Seconds later I had my WBO2 hooked up and talking to the MS. All this was done without changing a single setting (except to initialize WBO2 support).

Marty, to this day, hates me for that. He was working on his drift car that day and saw the whole process and just stood there, incredulous.

As far as tuning, most of it was done prior to taking it to the dyno. Really the only things that were changed were timing settings because they were set conservatively. MegaLogViewer is an awesome utility for getting VE tables set up (especially if you're new to it), and the autotune feature inside MegaTune is pretty nice as well once you get the hang of it.

Talk to Scott (braineack) about going the homebuilt route. I'm sure he can shed some light on that aspect of it.

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revlimiter

I hate to tell anyone that a project is a bad idea or not worth it or anything. EVERYTHING is worthwhile to someone. I wish you luck.

That said, I've learned this during my time with Miatas: a boring engine with a good ECU is a joy to drive. A fast/fun engine with a bad ECU is a nightmare. Mazda's first attempt at an OBDII ecu is what I'd quantify as "nightmare."

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Adam

Braineack

someone said home built MS?

cgoldhill

Can i "borrow" one of those ms setups?

FooSchnickens

I'm sure he'd let you if you let him "borrow" some of your money

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cgoldhill

Haha damn you saw right through my plan. Well i think im going to give my idea a shot and see what happens with it. I will be buying a spare manifold to cut up so worst case scenario is If it doesnt run well I'll just switch back over to stock, save all my bits and pieces and re use it all once I have MS installed and all. I won a set of GSX-R 1000 ITB's off ebay for 30 bucks shipped with the TPS sensor so now I feel compelled to take on this project.

Now all I have to do is sell my 240 to fund this endeavor, anyone interested in a race ready 90 240sx hatch drift car?

FooSchnickens

Talk to Marty. He'll probably know someone.

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cgoldhill

Very cool, thanks for the tip.