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Making my own EFI intake... The First Casting


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Ahhh, Lucal Slide Valve Injection...

 

I got SO lambasted for making comments about the way that system injects fuel (take a close look at the injection orientation)...

 

 

It looks like they're pointing towards the air stream. Kind of like "pissing in the wind"

 

As for moving the injector position, they will have the exact same rotation possibilities as the stock setup did, it's more movement than you think.

 

You could orient them all the same angle to front or rear, depending on 'harness drape' to give maximum visual effect with the loops of injection harness going to them...

Well I have a plan to try and hide the wires. Not sure if it will work or not though.

 

The only thing different I did on mine (other than mine leaked like a seive and sidelined my project---hint, don't simply think drilled finish is anywhere close enough! LOL) was I put the retention 'ears' for the screws up a little higher using a wider guide and the body of the screw to hold the cap straight instead of putting them at the bottom of the thing.

 

This kept the injector from hitting the 'ears' the screws go through, further restricting movement.

Well I orbited in with a .375" mill and then brought it to size with a boring head. Super smooth and true bore. I put a chamfer on the hole to aid in the insertion of the injector. The top of the injector hits a shoulder and then compresses the injector into the manifold making the vacuum seal.

 

Derek

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Well I have a plan to try and hide the wires. Not sure if it will work or not though.

 

How about running a second stainless line to each injector like you have for the fuel and putting the wires through that. You could somehow clamp the tubes to each injector together, with the wiring one on the bottom.

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How about running a second stainless line to each injector like you have for the fuel and putting the wires through that. You could somehow clamp the tubes to each injector together, with the wiring one on the bottom.

 

Actually my plan is to drill a small hole in the web and run the wires straight down and under the manifold. They'll go into the same loom as the balance vacuum lines and pop out at the log. I'll put the upper wires in gray heat shrink so they'll kind of disappear. I'm waiting until I get the header on my mock up head so I can see what kind of room I have to work with.

 

 

 

Derek

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Wow, even better. Consider some protection against the heat.

Like, use some Tefzel wire (Higher heat rated insulation) and some good quality fire/heat retardant loom. I like this stuff, you can't get it to burn even with a naked flame and it seems to block heat quite a bit. http://au.farnell.com/jsp/search/productdetail.jsp?SKU=1346821 Probably better stuff out there though.

With this stuff you will need 1 run of loom for two injectors as the biggest it comes in is 6mm.

 

Wow, I can't remember being so excited about someone else's project before.

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I put mine (I only had two injector leads to hide) inside vacuum tubing. I did use Tefzel as well due to my concerns with the heat. If it can lay across the bleed air plenum of a GE F100 Engine in an F15C, I figure it's good enough for me. Aircraft Spruce has it available, shielded as well for those TPS and CAS triggers... It was a very big decision fos me to put the injector UNDER the barrel, instead of firing down the throat as with the stock SU air Cleaner there are PLENTY of hoses running in there that wouldn't be needed with EFI, and more than an easy job to run the injector wires to them. Most of the other sensors were hidden similarly inside the maze of vacuum tubes on a stock 74 SU setup.

 

The injectors should be free-floating. They should be able to rotate. The fuel blocks should be at a fized distance to affect a seal, but not solidly clamp an injector. It should float slightly axially, bottoming before a seal is broken, and should easily rotate when everything is bolted down. A firm clamp will not only transmit a LOT of heat (o-ring being the only thing touching doesn't allow direct metal-to-metal transfer through conduction) it has a chance to distort the body when something grows through heat expansion.

 

As far as 'pissing into the wind' do it sometime and tell me what happens to that stream, and you will get the idea and impetus behind that type of positioning. The heated discussion I got into involved a nondisclosure agreement I had with Cosworth Engineering in Lomita after some site visits to their shop and discussing their Counterflow Methanol Injection Scheme for CART engines. I couldn't at the time tell the person on the 'other end' of the discussion where I was getting my information, but my contention was it was 'common' and spelling out which machines of the past 3 decades employed it (since he was totally unfamiliar with any of them) was counterproductive (old technology doesn't count, what uses it today was what his retort was, I believe...). Rest assured, when the story hit major automotive press, I recalled the earlier discussion and called out his 'what modern engines employ counterflow injection' and pointed out the article. Nothing is more frustrating to me than knowing some high tech stuff, but being covered by a Non-Disclosure. I wasn't in there doing engine development work or anything. I was attending to their compressors and air system in the shop....but when the engineers on the floor realized I was asking cogent questions and understood what they were accomplishing (as well as 'gazaming' over up-close and personal revelations of very cool features of the engines, they offered to give me a full tour...after reminding me that I DID sign a Non-Disclosure as a condition of being admitted to the facility! Then they revealed all sorts of neat things. That ND expired earlier last year matter of fact. Jan/Feb 2008.) Curiously their revelation on injector orientation was not public till almost mid-late 2007! Which is surprising given the fact that as the photo shows, Lucas MFI and others used counterflow long before Cosworth employed it. Hell, they were counterflow injecting the methanol in FRONT of the turbo to aid in cooling.

 

Hmmmm, what does that sound like?

 

The in-head Barrel-Throttle is what got me!

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The injectors should be free-floating. They should be able to rotate. The fuel blocks should be at a fized distance to affect a seal, but not solidly clamp an injector. It should float slightly axially, bottoming before a seal is broken, and should easily rotate when everything is bolted down. A firm clamp will not only transmit a LOT of heat (o-ring being the only thing touching doesn't allow direct metal-to-metal transfer through conduction) it has a chance to distort the body when something grows through heat expansion.

 

 

Hi Tony

I based my injector mounting on this info

We usually make these out of 1 inch bar stock. We like to seal the vacuum side of the injector with a 5/8 ID- 3/4 OD O-ring slid over the nose of the injector body. This will work on any standard injector. You can pull off the stock O-ring and pintle cap. Bore the bar stock to .640-.650, straight through. This allows a slight air gap between the boss and injector to reduce heat transfer and fuel boiling. A .740 counterbore, .040 deep is machined at the end for O-ring retention and sealing. We usually cut off the bosses at 45 degrees so that they are about 1.35 to 1.5 inches long. This is a good entry angle for many injectors into the runner and is an easy angle to saw at.

rx7-18.jpg

 

Taken from this site http://www.sdsefi.com/techinta.htm

 

At the time it seemed like the best way to go. There is quite a bit of air gap between the manifold and injector. The base of the injector body is sitting on an o-ring . I'm afraid if I don't have the injector clamped down I'll have a vacuum leak at the base of the injector.

 

I did use Tefzel as well due to my concerns with the heat. If it can lay across the bleed air plenum of a GE F100 Engine in an F15C, I figure it's good enough for me. Aircraft Spruce has it available, shielded as well for those TPS and CAS triggers.

 

After putting together a few CNC retrofits I'm a big fan of multi conductor shielded wire. I'm using it on everything. injectors, sensors, the works. And single point grounds as well. I learned one thing early on, noise sux.

 

Derek

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Hi Tony

I based my injector mounting on this info

We usually make these out of 1 inch bar stock. We like to seal the vacuum side of the injector with a 5/8 ID- 3/4 OD O-ring slid over the nose of the injector body. This will work on any standard injector. You can pull off the stock O-ring and pintle cap. Bore the bar stock to .640-.650, straight through. This allows a slight air gap between the boss and injector to reduce heat transfer and fuel boiling. A .740 counterbore, .040 deep is machined at the end for O-ring retention and sealing. We usually cut off the bosses at 45 degrees so that they are about 1.35 to 1.5 inches long. This is a good entry angle for many injectors into the runner and is an easy angle to saw at.

rx7-18.jpg

 

Taken from this site http://www.sdsefi.com/techinta.htm

 

At the time it seemed like the best way to go. There is quite a bit of air gap between the manifold and injector. The base of the injector body is sitting on an o-ring . I'm afraid if I don't have the injector clamped down I'll have a vacuum leak at the base of the injector.

 

 

 

After putting together a few CNC retrofits I'm a big fan of multi conductor shielded wire. I'm using it on everything. injectors, sensors, the works. And single point grounds as well. I learned one thing early on, noise sux.

 

Derek

 

 

Hey Derek-

Your project is looking awesome, really nice machine work and design. I think that the injector is going to be spraying on to your bar stock though. It is way too close and you would loose some atomization. It will work like that but it would be alot more effecient if you did not have all of that stock around the pintle.

 

Scott Holcombe

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I had found an engineering drawing of the recommended Bosch injector mounting, pressure side was 13.5 mm (0.531"), manifold side was 14 mm (0.551").

I bought a couple of straight reamers to finish the holes cleanly, drill them as 1/2", then finish to exact size.

Can't find the drawing or link now dammit, seems like it was on the Motec site.

 

Carter

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I wouldn't move the pintile caps. Strange things happen to the injector spray pattern when you do that---unless they are talking about somie sort of pintile/o-ring combination fitting like an MSD GM style injector or something.

 

Nissan clamped their injector bodies down using that big rubber ring, and a smaller flat o-ring on the pintile. I mounted mine using a standard O-Ring on the nose sealing like Nissans design, with the body clamp and everything. This let me the freedom to free float my fuel rail separately due to the close areea in which I was working. I got it all to fint inside, but there has to be an easier way. When I get the time, I'll work on it some more and eventually get it to where I like it.

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I wouldn't move the pintile caps. Strange things happen to the injector spray pattern when you do that---unless they are talking about somie sort of pintile/o-ring combination fitting like an MSD GM style injector or something.

 

Nissan clamped their injector bodies down using that big rubber ring, and a smaller flat o-ring on the pintile. I mounted mine using a standard O-Ring on the nose sealing like Nissans design, with the body clamp and everything. This let me the freedom to free float my fuel rail separately due to the close areea in which I was working. I got it all to fint inside, but there has to be an easier way. When I get the time, I'll work on it some more and eventually get it to where I like it.

 

Too late!

Since I opted to go with the procedure I mentioned earlier the manifold won't even accept an injector with a pintle cap.

I guess we'll just have to see how it runs.

 

Derek

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Got everything done for the test fit. The last part was the injection line looms.

P1010005.jpg

 

My plan was to anchor the looms with insulators to stop the heat transfer. I changed plans after the first set and decided to let the lines free hang and anchor the fuel block to the head. There's nylon tubing between the looms and the stainless lines. Mostly to stop electrolysis but it will help in heat transfer.

P1010008.jpg

 

The fuel block has the inlet on the bottom and the regulator goes on the side.

 

P1010006.jpg

 

There's a decent amount of air gap between the valve cover and the lines. If there's a version 2.0 I'll bring them even further out. I'm pretty happy with the lines as a first effort but I'd relly like to scrap them and start from scratch. Wouldn't be prudent at this point though!

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Wait for it

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Keep waiting

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BAM!

P1010009.jpg

 

Ok the scuzzy ass engine makes this pretty anticlimactic but I promise I'll improve that before I do the final install. It really looks a lot better in person.

And now for the bad news. I'm not really happy with the ascetics of the angle of the manifold. I feel it's pointing upward a little more than I would of liked.

Now for the good news. It hit's the hood so I have no choice but to fix it!

 

P1010012.jpg

 

I designed it to have the best possible (in my mind) angle into the head. I knew it was going to be close so I have plenty of meat on the intake flange so I can bring it down a few degrees.

P1010013.jpg

It's definitely Tuff looking though

P1010014.jpg

 

Now comes the hard part. Staying focused on work while this is going on.

 

 

Derek

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