Souk's setup looks NIIIIIICE.... I think if I ever build up an engine, I'd love to go with something like that!

Someone could have alternative engines to swap into the car . . .

Thanks Matt! Mike deverse all the credit for that project.

We're working hard to exploit the system Mike has developed. We'll have some nice basic maps to work from soon enough. Unfortunately we don't have numbers from his engine on the dyno with the Webers he sold to "trade up" to the EFI, but we'll definitely have dyno numbers when his engine is tuned.

We're also building a 3.4 engine over the winter that will use the ITB-EFI setup, with twin-plugs and new cams that are currently being developed. First dyno results were very VERY promising, with peak HP over 330 at the crank on a 3.4 with carbs and those cams...I can't wait to see what the ITB-EFI will do.

We also have a client building a hot rodded 2.7 for his DE/street car that will use the system.

Mike will probably stumble onto this thread, or you can check out his thread on the system where there is a lot of information.

http://forums.pelicanparts.com/showthread.php?s=&threadid=225593&highlight=motomo tions

That's what I'm doing with the 3.4 John. My '76 still has to be emission tested in Illinois every two years, but it'll sit on the shelf when not on it's way to the test station :)

OK so what diameter is this common plenum? ITB/Megasquirt is really a dream of mine. Didnt know it would be possible before this thread.

Sometimes it's hard to obtain good vacuum when running hot cams and ITB's...in that case using Alpha-N method is better than MAP.

Alpha-N means that computer only cares about throttle position and RPM. Bonus is that motor behaves very MFI-ish with such setup (MFI is basically nothing else but Alpha-N setup realized in mechanical non-programmable compontents)

and let's face it boys, deep down , it's mfi you want
y'all are just in denial about it :D:D

Well I believe people want instant throttle responce and good performance from their EFI.

MFI offered that, but it's technologically "locked" to WWII technology...Alpha-N EFI will give you all that, cheaper and more flexible.

Alexander,

The TWM's have a port on each throttle body that I tied together a vacuum manifold that I got from McMaster-Carr. I used 3/8" fittings IIRC. I'm not sure of the length of the manifold, but it has 3 ports on the front and one on each end. You can see it pretty well in this picture (little black box at the firewall):
http://www.motomotions.com/images/P6250001.JPG

Some people have run lines to small fuel filters if that gives you any help on volume. From the manifold, I ran a line to the Megasquirt controller. I was able to get a fairly stable MAP signal at idle with this setup.

However, Goran is right about alpha-n. Through my tuning process I decided to ditch the speed density (MAP/RPM) and go with alpha-n (TPS/RPM). I just couldn't get a good consistent MAP signal with my setup, at a 2500 rpm I was already at 100kpa. So, I am in the process of dialing in the alpha-n tables. I will have more info soon...

Problem with Alpha-N is that it's somewhat instable. You usually build your engine, make sure everything works and then do the mapping. Alpha-N doesn't like big changes...put on different filters, change cams or headers or simple thing like gearing of throttle-linkage and tables go out of whack.

When it works it works very well...but all mechanical fiddling must be done before mapping or you are forced to map it again. Due to it's simplicity, it's much more sensitive for VE changes than MAF-equipped cars. On the other hand, it's simplicity also means it doesn't care about vacuum or hot cams...it's completly blind for noise in vacuum signal as it doesn't need one.

This is interesting. I'm learning a lot from you guys, thanks.

Could anyone explain (or link to an explanation) how the ECU uses the vacuum signal and the advantages of doing so, versus ignoring the vacuum signal? My understanding of this stuff is really weak.

Also, with alpha-n, can you still use a knock sensor to protect against detonation?

Finally, Mike how are you doing the mapping? Do you have to spend a fortune on dyno time or can you do it on the road / in the garage? Is this a high-tech process involving a laptop and lots of data analysis?

isn't knock protection based on ignition retarding? if so , then i would think this wouldn't be a problem sine alpha-n is a fuel delivery thing , not an ignition thing...?

i suppose it's not much different from mfi tuning

you need a base to start with
for mfi that's the space cam

for efi , you'de have to guestimate a bit
or use one from somebody who has a similar engine

then either strap it to a dyno , and have a wideband sensor up it's tailpipe

or run with an LM1 hooked up...

that's for the fuel at least, if you run electronic ignition , it becomes slightly more complicated , since you also have to figure out the ignition at the same time...

Most of the mapping can be done with the use of a wide band O2 sensor (PLX Devices, LM-1, etc...)and a laptop or palm pilot on the road. This is what I am doing. It would work the best if the wideband in wired to the Megasquirt. Megasquirt has software available that allows you to input your datalogs and recommend maps based on the data. In addition, as long as you are using wideband, you can also program the ECU to meet specific AFR (air/fuel ratios) for your VE (volumetric efficiency) table. For high load tuning, some dyno would be handy, but not required.

<edit> The ignition maps can be extrapolated from distributor curves and programmed into the ECU to get you up and running, but dyno time is highly recommended to get the timing dialed in.

Those ITB's are gorgeous. But they make me wonder...if you guys already have those things running on an EFI system with electronic ignition timing, then do you really need to have a throttle? If you have the computer controlling the fuel and spark, then why not use those two parameters to control the RPM's and remove all restrictions from the intake?

Oh yeah, and does anybody know about Ferraris' ITB's that supposedly change length depending on RPM in order to dynamically "tune" themselves? I met a guy at autocross last year who drove a Maserati and claimed his motor was the same as the Ferrari version except for the "variable length intake" trumpets. I always wondered if he was pulling my leg.

You need throttles to keep fuel / air ratios close to stoichiometric (14.7 to 1). Diesel engines vary fuel to develop more power (no throttles). You have to meter both air and fuel in a gas engine to keep the ratios the same.

Doug

those length changing TB's... you mean like Vario Ram , Developped by Porsche for the 993 ??? :D

Boy, those are funny looking air filters:D

If you need a track test car in florida, you can put me on your list.:)

Yes, variable length pretty much has to mean variable _apparent_ length. It is possible to have sliding concentric tubes, but they would be troublesome with a little grit -- and -- why bother.

you could off course devise something in the intake manifold, below the butterflies with springs
so they are "deployed" at lower revs, and upset the air flow so you get the same effect as short stacks... and at higher revs, they are closed by the air flow/pressure...

movable parts , they would have to be durable and heat resistant...and able to withstand the burping caused by hot cam overlap
only takes one failure to have chunks in your engine.. wouldn't trust it myself, but i guess it is possible

as far as i can tell, varioram style systems are never with ITB's/butterflies...