matt-tastic

Has anyone ever heard of this fuel unit? I have a friend that was talking about it and said it can work on a car with a MAF "Hot Wire".

Braineack

iTrader: (62)

good thing you have a flapper style AFM.

matt-tastic

Well, I'm kind of torn between finding a used fuel management system and just going through the hassle of running a vacuum style unit + injectors + fuel pump. If i read correctly, the stock fuel system will run 300hp before running out of steam. And I'd almost rather spend a few extra dollars at the beginning than going the cheaper route and having to rework the fuel system once I realize 200hp is not enough.

So basically, I've been told these cheaper Fields units run well on Supras and other cars with a hot wire MAF so I was thinking about running this unit and an MSD Timing Retard vs. running the cheaper way around.

patsmx5

iTrader: (16)

You car does not have a MAF sensor. Get a MSPNP. Done.

samnavy

iTrader: (7)

Correction. The stock FUEL PUMP will FLOW enough fuel for 300whp at stock fuel pressures... if you have a large enough injector and ability to control it. But the pump is only good for about 80psi on a good day. Even with the commonly accepted size of 330cc being the largest injector the stock ecu can handle, that's only good for 200whp.

So, a very common "complete" bandaid setup would be:
Walbro 190lphHP
Supra 305's
Bipes
O2clamp
Begi 2025 AFPR
With any small/medium T25@12psi boost and 100psi of fuel pressure, you make 200whp/180wtq. A GT2560 on a 1.8 with that setup will make 220whp. Properly tuned, your AFR will curve about 2-3points... the clamp lets you keep AFR in the 10-10.5:1 range at boost onset, leaning to 12.5 or so midrange... and the stock ECU riches things to 10:1 up top. You can lean it out a little on top to make more power, but that runs you dangerously lean in the midrange. You can raise the boost a little to lean things out up top, and pull a little more timing, but that hurts midrange torque. The stock ECU's fuel curve is the limiting factor in making power. The factory timing curve is actually pretty decent for boost, and the knock-sensor equipped cars do even better.

But the O2clamp and Bipes require you to hack up your factory ECU harness that you have to then repair to install MS. Don't do it. Conventional wisdom, doing it correctly from the start, from guys who have been there... quality engine management should be your first start. Get MS installed, tuned, and running on the car bone-stock, and drive it for awhile. Then pick a day to install the Wideband and MAF delete. Then pick a day to install injectors and retune fuel. Take your time buying quality turbo hardware and do it over the course of 6-10months... which is much better than going super-cheap all at once and having the car be broken for that amount of time... then spending your money on a ring-job because you boosted 12psi on the stock fuel system.

matt-tastic

Argh. OK. Let me ask you this though, with a MS, if I understand correctly, it will do EVERYTHING you need to run FI. I am just puzzled on how to get it to pull timing based on manifold pressure? I did not see a vacuum port on the MS. Or do you just run a set timing map in the MS? Or will it not pull timing at all and a separate unit is needed?

On a better more positive note, I did find a tubing bender to build a cage / bar (undecided) today!! At least that's something I know how to mess with. And has anyone ever seen how cheap tubing is compared to the price of bars? 20ft stick of DOM 1.75 .12x wall is like 45-50 bucks.

patsmx5

iTrader: (16)

Megasquirt will do everything you can think of. So yes, it will control timing six ways from sunday. Type in "megamanual megasquirt" in google and read up. It's huge. It's like the bible on megasquirt though. Anything you could ever think of that's not currently under development is there. For example, you could read about "timing" for 2 days if you wanted to. Plenty of info there and a FAQ to answer the simple questions fast.

Seamless tubing?

matt-tastic

Holy **** that's alot of info. Thanks for the heads up. And yes, seamless it is supposed to be, it seamlessed kinda cheap to me (haha get it?), but that's what I was quoted from a company that I usually purchased material from.

samnavy

iTrader: (7)

Megasquirt is an engine computer. It can completely replace (standalone) your stock ECU, plugged into the exact same harness connector your stock ECU does, or it can be run in parallel with the stock ECU. In parallel, only the wires that control fuel/spark/sensors are routed to the MS, then ones that control OBD/idle/AC/security/etc... are still attached to the stock ECU. This takes a "patch" cable that is easy to make or have made for you.

YOU program the Megasquirt to do whatever you want with regards to fuel and timing. Most people start with a base map (MSQ) which is the entire set of parameters (hundreds of them) to run the car. You can get this MSQ from another member of the forum that has a similar setup to yours. Start with that, and use the built in tuning software in Megatune/Megalogviewer to sweeten up your own individual MSQ.

The Megasquirt take all the inputs from all your stock sensors, has an onboard MAP sensor, input for wideband, IAT, knock, coolant, etc... and by evaluating these inputs as you drive in boost, you can add/subtract fuel/timing by just clicking the mouse. Running too rich at 4000rpm and 8psi of boost?... Click-click-click a little less fuel... go for a drive, datalog... fixed. Knocking a little at WOT between 3000-3500?... Click-click-click-subtract a little timing... go for a drive, datalog, fixed.

You REALLY need to find someone in your area to go meet up with and show you how easy the whole thing is. I understand your apprehension, it seems extremely complicated, and it's not. If you saw it in person once, everything would come together and you'd have no more worries.

matt-tastic

Well I did meet a guy the other day named Abraham?? I think?? He owns Able Racing here in Midwest City. They have built quite a few very fast cars and I believe have a decent understanding of MS, however, on the rest of the project I don't think they have built many Miatas, if any at all. I guess I just need to quit whining and get on with it. I just really didn't get how comprehensive MS is and how lackluster everything else, at least, seems to be. In addition, I came into this thinking I was going to be able to pickup a turbo kit relatively cheap, however, now I've kinda got a bug, in that, I figure if I'm going to spend this much, I might as well do it right and make a decent amount of power. I came to the realization that to have 5k in a decent track car really isn't that bad. I've had more than that in bikes before and they seem to be much more prone to sliding down the track (and doing damage to themselves) than cars. LOL

Joe Perez

iTrader: (8)

Indeed. Although it's build on fairly primitive core technology (who uses an 8 bit CPU anymore?) the Megasquirt is a surprisingly capable ECU. You asked a few posts back how it can "pull timing based on MAP". It's important to understand that the MS isn't a piggyback, it's a full-on replacement computer. So it's not "pulling" timing so much as it is in full control of timing. And the MS lives and breathes MAP. When you install it, you can remove your stock air flow meter altogether- like many modern high-performance vehicles, the MS system runs on MAP and RPM alone. As you research it, you will find that most of the important tables, such as the fuel table, the spark table, the boost table, the AFR table, etc., are 2d "spreadsheet" style charts with RPM on the Y axis, and MAP on the X axis. Here is an example:



The numbers in the cells are ignition timing in absolute degrees BTDC. So you can see that, at 4,000 RPM, if you are at 43kPa (about 17") which is a light cruise situation, the spark advance is at 34°. When you hammer on it and are now at 184kPa (about 12 PSI of boost) the timing is now at 14°. The system smoothly interpolates between cells as you move about, to produce a reasonably smooth output.



As to the shop you refer to... I'm always torn on such matters, as I believe that the best way to know your car is to build it. I'm not saying you have to do your own machine work, but to me, things like a turbo kit and a Megasquirt fall into the category of relatively simple bolt-on mods.

That said, I realize that not everyone is comfortable with this. If the shop you're looking at knows the Megasquirt, then to me that says they at least have some experience and knowledge of the subject of turbocharging imports. And apart from the fact that the flywheel is pointing the "wrong" war relative to most other rice-burners, there's not much that sets the Miata apart in terms of complexity or fundamental operation. In some ways it's simpler than your average Honda, as it lacks some of the complexity of those engines such as VVT or ludicrously high compression. It's really quite an easy car to work with the the grand scheme of things.


I guess it depends on your definition of "everything". There are other ECUs on the market that are just as capable, but what sets MS apart is its price. The Hydra Nemesis, for example is a popular ECU in the Miata domain, however it costs over $2,000.