Throttle bodies for Megasquirt

[Bullet Bob]

Okay, I planned to get on this about six months ago when I received my mill but It keeps getting pushed back because of higher priorities (day job). I am now ready to give this a go though I need some help.

I plan to develop inexpensive throttle bodies that can be used for EFI conversions and these will be specifically for the 911 engine. Unfortunately I do not have an engine I am converting so it makes the trial and error portion a bit tougher.

First question... Do most people upgrade to the Megasquirt EFI for reliability reasons, or for performance, or both?

If going for performance, would a high butterfly setup be more beneficial? How about individual barrel valve throttle bodies?

My though was to sync these in much the same way as the high butterfly system (http://www.eurometrix.ws/highButterfly.html), though these would be individual units. Any forseen problems with that approach?

I also assume these would need mounting provitions for a throttle position sensor, correct? Are these pretty standardized? If not, is there a particular brand or model I should design around?

In a previous post regarding this exact same topic someone recommended designing around Bosch fuel injectors. Is there a particular model or part number I should use? I will also investigate adapters for mechanical injectors per a prior request.

What intake port diameter range should these be available for (35mm, 38mm)?

Lastly, any guinnea pigs out there that want to be part of the prototype/ initial testing part of this? This will happen eventually and though I hate to put a specific date on it, I would like to have the prototypes (billet machined, anodized red?) done in the next few months.

I look forward to some feedback.

Bob

[Vipergrün]

Bob, sounds like a great project. To me, simpler is better and the fewer moving parts the better. You may consider modeling after the TWM 3003 series of TB's. While not true ITB's, the are similar (basically replicas) of the Weber IDA series and I believe use the same or similar linkage. However, true ITB's, like the TWM 3006 series or Jenvey's are the bomb.

I think most folks use MS ECU due to its affordability and tuneability aspects. Quite a few folks are running them and they appear to be reliable as well. The installation of the MS relay board is almost a necessity for a clean installation

Yes, a TPS setup would almost be mandatory.

You may want to have provisions for both the Bosch-style and Pico injectors (shorter ones). I believe only the fuel rail mounting would be affected to accomodate the different 'heights' of the injectors. IIRC, the bungs are the same between the two.

Please keep up updated. I would LOVE to be a guinea pig for you

cheers
-Brad

[lateapex911]

I am working on a similar system for my car. The guys at Motomotions, (Mike and Souk?) who post here have a great kit set up that includes the ITBs, the Megasquirt, the injectors and rails, and relay board and so on. It's priced pretty reasonably too.

I like the kit, but have a few reservations, no doubt they are probably unique to me, LOL

I like the look of the iTBs, but not the rails and injectors. For an old car, I think that modernization is cool, but, the appearance of all that gear doesn't thrill me.

I'm looking into using a set of MFI TBs and stacks, and hiding the injectors and fuel delivery system. persona preference, perhaps, but you might want to consider that in your desgn, if you find others who agree.

My reasons for switching are basically better day to day operation. I don't ecpect a significant power increase over the Webers, but drivability should be far better.

Just some thoughts for you.

[Vipergrün]

Originally posted by lateapex911


I'm looking into using a set of MFI TBs and stacks, and hiding the injectors and fuel delivery system. persona preference, .......

Late, are you putting the injectors in the heads like with MFI? Are you able to fit a TPS to the MFI butterflies?

Thanks
-B

[lateapex911]

WEll, I'm in the research stage now. So I haven't finalized anything. But I would like to NOT pull my engine apart to do this, LOL. So nothing in the head. I have been considering high mounted injectors, but I'm working thru the issues with that right now.

In the long run, I am sure it would be more prudent for me to just get the Motomotions kit, and be done with it, but a little research can't hurt.

[rfuerst911sc]

I am running a Motomotions EFI setup with the TWM's and they are a nice piece. They are quite simple as basically it just has butterflies,air adjustment screws,vacuum ports and on the passenger side a TPS sensor and ofcourse the fuel rails and injectors. The way the injectors are angled you really have to look to see them plus the air cleaners help hide the injectors. And they mount on Weber manifolds and utilize the stock throttle linkage and sell in the $1200.00 ballpark.

[Bullet Bob]

Does anyone have experience with barrel valves? What about ITB barrel valves with top mounted injectors?

Jake, what is your timeline on coming up with a solution? Would you be interested on collaborating with me on this? Is this for a 2.7? If so, I currently have one sitting in my garage on an engine stand (2.7 RS-spec, MFI) so getting things to fit right would be easy.

Bob

[Bullet Bob]

Originally posted by rfuerst911sc
I am running a Motomotions EFI setup with the TWM's and they are a nice piece. They are quite simple as basically it just has butterflies,air adjustment screws,vacuum ports and on the passenger side a TPS sensor and ofcourse the fuel rails and injectors. The way the injectors are angled you really have to look to see them plus the air cleaners help hide the injectors. And they mount on Weber manifolds and utilize the stock throttle linkage and sell in the $1200.00 ballpark.

I am hoping to come up with that sort of package in the TWM 3006 style with the linkage, bodies, and manifolds for a similar price. I think I can make it work but we'll see :-)

[lateapex911]

Time line?? Whats that? LOL. I have crapy Webers on it now that need rebuilding, but it is drivable, just annoying.

It's been a long time to get to this stage so there is no real rush. I'm digging thru the options now. I used to work in vehicle and product development design and fabrication, so i know the calender issues, !

Motomotion has put together a pretty neat setup...but the kit is a lot more all up. I think the $1200 price mentioned above is for the ITBs only, and the lesser of the choices.

My car is a 2.7, solex cams, (Kinda like E cams, I think) and just under 10 to 1 cmpression, if I recall correctly.

[rfuerst911sc]

Yes the price I mentioned was what I payed for the throttle bodies only.

[Bullet Bob]

How about the throttle position sensors, are those pretty much one size fits all?

[rfuerst911sc]

There are many configurations of TPS sensors, my recomendation would be to design your throttle body to use a cheap readilly available GM or Ford sensor. When I researched the TPS sensor that is supplied with the TWM throttle bodies it is a Range Rover part!!! Not easy to get on a Saturday afternoon if you had to.

[Bullet Bob]

What port size should they be built for?

[herman maire]

Great discussion...... I was speaking with the TWM head office a few day's ago.When I mentioned the 3006 series he told me to stay away from those for a street/track car. He told me the 3003 were the way to go for a car driven on the street/track.

He was even steering me away from the more expensive 3006. What does this mean.... I dont have a clue . The $1200 was not that bad either.

What makes the 3003 not a ITB set up vs the 3006????

[herman maire]

Oh..... He also said 46mm were plenty even for my 3.6 VS the 3006 with 50mm+

[Bullet Bob]

Originally posted by herman maire
he was even steering me away from the more expensive 3006. What does this mean.... I dont have a clue.

Why was he steering you away from the 3006?

My guess is bore sizes (not sure what the minimum is for the 3006), throttle linkage adjustment difficulties (would need to be re-tuned if they were taken off the engine), and air filter selection (the spacing of the three throttle bodies is wider that a Weber type setup). These are just guesses though.

[Vipergrün]

Originally posted by herman maire


What makes the 3003 not a ITB set up vs the 3006????

The 3006 is a true ITB, whereas the 3003's are a *unit* if three throttle butterflies, not truely individual. Are you guys getting a quote of 1200.00 for the throttle bodies, manifolds and linkages??? That seems really low. Thanks!

-Brad

[Bullet Bob]

I guess I mis-quoted the post above. I went ahead and edited it.

Any ideas as to why they would steer Herman away from the 3006 setup?

[herman maire]

Originally posted by Bullet Bob
I guess I mis-quoted the post above. I went ahead and edited it.

Any ideas as to why they would steer Herman away from the 3006 setup?

Hey Bob..... The impression I got was that the 3006's with the larger throttle
body's 50+mm will only be happy in the higher RPM. He told me that low speed
driving in the low RPM would not be enjoyable at all.

I dont know what to think..... I guess I am always looking at the more expensive
model and thinking " I need that one" but if the cheaper 3003's can do the job and they are alot cheaper.... That makes them pretty damn attractive to me.

By the sounds of it, if the 3003's are plenty with a 46mm throttle body for a 3.6 they could easily handle 2.4-3.6 who know's maybe even 3.9

I am going to messure the diameter of my runners on my stock 3.6 intake manifold just as a comparison.

I just hope the sales guy know what he is talking about heh, heh. If he does'nt
jeeeeezzzzz that would be dumb.

[Bullet Bob]

That makes perfect sense, just like buying headers that are too big in diameter hurts low end performance. So if a 3006 style throttle body was available in 44-46mm it would be the best of both worlds, right?

Also, how much are the 3006 units as a set?