Spittybug - Designs for converting stock setup to EFI

[Ron]

Makes sense to me but don't you want some "curves" in the plumbing to flow the air?

At first I thought it would be good to leave the W pipe because of that, but thinking further about factory setups, I remembered that the throttle body dumps straight down against the 'floor' of the manifold like a carb (some even have ribs right under them that the flow collides into). Now which is better that far up stream is beyond my knowledge...I know who to ask if someone else here don't know for sure. But I doubt a D could draw it hard enough to make any real difference that mattered....?

; things that work fine as is, so why mess with them?

I was thinking- 'To take advantage of all of the things that are already around'...all we would have to do is build a thin aluminum box, weld an eBay adaptor on it and the rest (throttle body to brain) is laying all over the junk yards.
I'd like to play with any of the several options but I'm not sure what has priority over what for you. I don't want to beat a dead horse here ;-)

Admiral's option of creating an air intake adapter is kind of optional in my mind; cleans things up a lot but isn't required so long as the air deflector plate is removed/locked open.

Split the difference and remove the upper half of the mix unit...?

[dmc6960]

If I was a good fabricator, and the Z7U EFI manifold never existed, I would have mimicked the stock mechanical setup in an EFI form. Instead of fuel rails, I would have a "mock" distributor in the stock location with braided fuel lines following the original locations to the injectors. Unsure how I'd hold them down though, never had to think that far. I know the injector seats are pressed into the heads, so they can be removed, and perhaps replaced with something a little shorter to better accommodate EFI injectors. In this setup the stock idle motor would remain, the cold start valve would be capped off, or possibly the top of the brass pipe modified to be a direct transition to the idle motor. The transition between the air filter and throttle body would be newly fabricated (not a hollowed out K-Jet venturi). This would also have a barb for the idle motor air source, and a bung for the intake air temp sensor. Ideally the temp sensor would be right after the throttle plates and where the idle air rejoins the manifold (best for temperature taking), but that would not be possible using the stock manifold in this manner. An alternate method could be to incorporate the idle motor in with the venturi replacement (sitting in-between the two intake banks) and deposit the idle air where the blanking plate is on the W-pipe. That would free up cylinder #4 for those who dont like taking an extra 2 minutes to remove it when servicing the injector or spark plug.

If you haven't guessed, I'm real big on stock appearances. This is why I've fitted the stock airbox on top of my Z7U manifold. When I eventually get an engine dyno, I'll also experiment with a fitted cone filter to see if it makes any difference. If it does my decision to keep it will probably be based on how big the improvement is. A stock engine shouldn't expect to see any gain, but my engine is far from stock.

[Spittybug]

I've had a PM question on some of the terms in the thread. Just so that we are on the same page, technically correct or not, this is how I've been referring to things:

• W pipe = Horns = Small cast piece between throttle body and manifold
• Manifold=Plenum=Single large cast piece the size of grandma's rocking chair
• Throttle body - contains butterfly valves, connects to W pipe on one end, fuel distributor on other. Has throttle linkage on passenger side
• Fuel distribution unit = Octopus - Everything "upstream" of the throttle body up to the air filter
• K-Jet "stuff"= All that can be revoved once idle air and fuel injection is done
• TPS = Throttle Position Sensor
• MS II = Megasquirt 2
• MAP = Manifold Air Pressure (sensor found on MS circuit board)
• CLT sensor = Coolant temperature sensor
• Innovate LC1 = Wideband oxygen sensor
• IAC = Idle air controller - two basic varieties, open/closed and stepping which is more precisely controlled. I'm NOT referring to the stock one unless specifically stated
• Y Pipe = Coolant pipe down in the Valley of Death
• North and South = Upstream and downstream respectively (tailpipe is deep south )

Sorry for any confusions. I'm going to take a look at what an adapter would need to look like if we removed everything North of the throttle body.

[sean]

W pipe = Horns = Small cast piece between throttle body and manifold
102279.jpg
Manifold=Plenum=Single large cast piece the size of grandma's rocking chair
102260.jpg
Throttle body - contains butterfly valves, connects to W pipe on one end, fuel distributor on other. Has throttle linkage on passenger side
102856.jpg
Fuel distribution unit = Octopus - Everything "upstream" of the throttle body up to the air filter
102807.JPG
Y Pipe = Coolant pipe down in the Valley of Death
102147.JPG

[AdmiralSenn]

These aren't the best pictures (engine bay was still dusty and many of the hoses and wire looms are just "floating" because I was still playing with lengths and routing) but here's a rough idea of what my engine compartment looks like using a stock manifold and rails in the original ports.

P9240038.jpg

Here's my Rice-a-Roni air intake - the adapter is just jammed into the rubber transition piece that attaches to the throttles, the fight is so tight that it doesn't really need anything else. I'll be putting a bracket on to secure it better anyway, but it works like this.

P9240039.jpg

The brackets I use to hold the rails down. Plenty strong enough to keep them from moving - no fires this time!

P9240036.jpg

And the whole thing in all its unfinished, kind of gnarly glory.

The only issue I have with this configuration besides the spark plugs being a tad more annoying to get to is that I haven't gotten throttle acceleration worked out yet - getting it into first without stalling it is a little tricky. My previous tune had addressed this and the car ran fantastically well, so far this build looks like it'll run at least as well if not better.

[Ron]

These aren't the best pictures...

What is it...3000 words?...I like it so far!

[Spittybug]

Adam, it's hard to tell from the pictures, but how much clearance is there from the fuel rails to the spark plug boots and to the sides of the manifold? Would you think that a fuel header and 6 braided hoses to the injectors would be better?

[AdmiralSenn]

Adam, it's hard to tell from the pictures, but how much clearance is there from the fuel rails to the spark plug boots and to the sides of the manifold? Would you think that a fuel header and 6 braided hoses to the injectors would be better?

The fuel rails rest just high enough for the spark plug wires to curve gracefully out of the way instead of being smashed down. The inside edge of each rail is almost exactly in line with the outer edge of the manifold on each side.

A manifold + hoses system would work great for ease of access but would be a plumbing and mounting nightmare.

Consider: If using standard EFI injectors, each injector must be securely clipped down somehow into the port. Then each hose must be VERY securely attached to each injector - hard to do with a press-fit o-ring fitting. There are some clips out there to clip an injector to a rail - I have a few different ones I might be able to scrounge up and photograph - but you'd probably need a "cap" of some kind that would accept such a clip, with a threaded connection on the other end.

And the manifold has to go somewhere too. This means fabricating something to hold it like the bracket that holds my regulator.

Other than that it would work great, and probably use about the same amount of hose that I used. Probably a few extra fittings though - you'd be adding twelve for the injectors (one for each end of the hose) but you'd be eliminating the Y block and duplicated plumbing that I used. I figure 27 total fittings not counting the manifold itself or the plumbing for a regulator.

Definitely worth considering. I think the manifold would almost have to be custom made, though.

(Also, d'oh! "Fit is so tight", not "fight is so tight" in my previous post. Whoops.)

[AdmiralSenn]

Do we know of anyone running a wet, stock manifold, carb or EFI?

I forgot to add that there is someone using a factory manifold with injector bungs added into it - the rails sit between the plenum boxes. There were pictures on the .com archive, they may have been a member too. Not sure. I want to say that Martin supplied the pictures but I could be way off.

I don't remember how they handled air intake though.

[dmc6960]

I first posted that picture to DMCTalk.com, but the original credit goes to Cineman. It was in either an Alpine or a custom built racer. There was a throttle body attached directly to each plenum. The engine suffered a fire, I think during a race. I don't remember if it's been rebuilt since.