fuel injection for the log?

CobraSix

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the divide log topic on the 200 forum got me thinking.

What if you were to put a TB on the log in place of the carb, and put 2-4 injectors batch firing right in the log (or 6 pointing right at each runner?) Seems to be a pretty easy set up. Just widen the inlet some for a TB from a 5.0...slap a MS or SDS on there...

Slade
 
It's a lot of money to convert a log to EFI (something besides a simple TBI). Injector location and angle is critical. You wouldn't be able to use a single fuel rail either because the runners are all at different angles. Once you get done, if you ever crack/warp the head, or drop a valve you have a lot of work down the drain.

That said, why not divide the log and run a couple of TBIs from an HSC motor (Tempo or Taurus)? That would be simpler, look really cool (ever seen one?), and I would gamble would make more power from better airflow.

Simpler yet, run a CFI unit (Ford's TBI). If a 2100 Autolite can be made to fit a log, this will fit just the exact way.

You have to keep the cost down on these ideas. For almost the same money to put MPI on a log head someone could do a Oz head or even venture a x-flow conversion and get way better results. Did you know, that there are NEW heads being made in Argentina? 250-2V Killin' SP heads at that. Problem is, no one has had the capital and interest to bring any up.
 
u couldnt just grab a fuel injection setup from a toyota inline or something like that (i seen one at pick-a-part, but it was already half apart)...how crucial is the angle and why? Definitely a good idea though...what about a fuel injection from a V6..then u could split the log in half and put 3 to a side...hmmm. if u got a spare engine and time and money then it would be worth a try.
 
I hate to disagree with Inliner, but injector angle is not critital, so long as it isn't so flat as to have the wall inferfere with the spray pattern. OEM port injection systems have to meet all manner of EPA and DOT tests that have little or nothing to do with what you are asking, so you should feel free to mount your injectors at any reasonable angle, from about 15 degrees incline (minimum) to 90 degrees on the runners, to straight in from the outboard side of the log (centered over each runner). All would work about equally well, and any would be totally superior to the center-mounted carby position.

IMO, about the best place to mount the injectors is with about a 20 degree angle (from horizontal) right inboard of where the indivudual runners branch off the log. That way the spray pattern is inside the runner, but as far from the intake valve as possible, since that promotes maximum evaporation. It is easy to do, too, since all you'd have to do is chuck up the head in a drill press at the right angle and drill the injector bosses. Alternatively, make a jig and you can skip the drill press.

Now, the difficult part is getting the 'yoda ECU to talk to the Ford lump... :shock: :D ;)
 
Stan,

Place the injectors as far away from the valve as possible? That sounds new to me. The angle may not be very critical, but idealy, you would at least want them all at a similar angle. As for the angle, there's no way to use one fuel rail and have all the injectors at the same angle. 20* from horizonatal may be ideal, but the problem is that the runners are at different angles. You'd need at least 2 if not 3 rails to keep the injectors at a similar angle. Now, moving them back towards to the log, does help you out as far as there being less runner angle difference, but you will end up with the fuel rain interfering with your throttle body....

I'm not saying it can't be done, but the log is just a horrible candidate for this swap, and in the end, you are still breathing through it. If the object is performance - you are screwing yourself. If the object is just driveability, that can be done a lot easier via TBI.

Slade is approaching this the right way. The Aussie manifold is a perfect platform for MPI.
 
Yes, place the injectors as far as possible from the valve to provide the maximum time for the fuel to evaporate before entering the cylinder. It is an old racing trick that has been used for decades. Some racing engines even mount them a couple of inches above the bell-mouths of the trumpets, adding even more time for evaporation.

The idea of placing them near the valve only came about in response to pressure to reduce emissions. Placing them near the valve ensures all the fuel goes in the intended hole, but at the cost of less time for evaporation. Nearer the valve also makes for easier packaging in many cases, and results in lower shut-down emissions.

As for the fuel rail interupting the TB, simply use two rail sections, connected by a curved section of hose. In any event. the angle of the spray pattern isn't important, even if it's not parallel with the runner. So long as the spray cone doesn't intersect the wall the airflow will ensure that the fuel makes it to the cylinder.
 
Sorry if this sounds stupid but why can't you use something from a datsun. they were I6 and EFI. got a 280z but really havn't looked. just wondering.
Paul
 
Thanks Stan. It makes sense now. Still polishing a turd IMO, but....
 
Stan is right about angle not being so critical, but 'as far from the valve' doesn't always hold true- it depends on whether your manifold was designed for wet flow or dry flow. Keeping a predictable spray pattern near the valve does several things:
1. cools the valve a bit, also helping to vaporize the fuel. Believe it or not, EFI guides actually last longer because there is less A/F 'saturation' in the port over a given time (which washes off the light oil).
2. promotes consistency between cylinders.
3. avoids the dreaded 'puddling' at certain speeds.
4. the patterns are often tuned as part of swirl ports & chambers. The 2V and 4V Tritons are done so, as well as the GM LS1.

For angle, that's also a function of flow range. Like I've said before, some high HP setups actually angle the second injector (on a dual setup) back 20-45 degrees to help dispersion.

EFI on the log head is basically putting a skirt on a pig- there simply won't be enough airflow to be able to justify it (without major rework).
 
Just thinking outside the box for discussion's sake.

I plan to do MPFI on the Aussie manifold, mounting the bungs about an inch from the flange and at about a 30* angle to line it up pretty close with the runners on the head.

Slade
 
One other problem brought up before with no remedy.

Due to the cast on log manifold shape and manufacturing techniques, the air flow to each cylinder is not the same, some runners flow better than others, some worse. Air flow to each cylinder not being the same, no way to match injector output to match each separately. Computer commands each injector to supply the same amount of fuel to each. The middle two could be perfect and the end ones would be rich.

The only EFI that is going to work is a single TBI, one air entry point and one fuel injection point so it is "premixed" to the same F/A ratio prior to entering the runners. Each cylinder could get different volumes of fuel/air mixture but the F/A ratio would be the same.

It would be difficult to make a dual TBI system flow the same volume and achieve the same F/A ratio from each.
 
You guys all bring up great points. In my defence I was simply trying to answer Slade's question directly without either snowing him under with too much info or discouraging him from experimenting on his own.

Yes, we're talking about polishing a turd here, I'll grant you that! :D But it's a fun turd to polish, and playing around with them provides endless hours of harmless entertainment for Little Johnny. We all know that nothing is going to turn this sow's ear into a silk purse, but that's not the motive. Heck, if we wanted to overcome the log-headed engines' shortcomings, we'd just drop in a five-oh with a T5 and be done with it. Call us stubborn if you will... :LOL:

Jeff is right about dry runners. Try my suggestion on a five-oh's 270-ish degree intake system and I doubt it would even run. I was talking specifically about the short, relatively straight (wet) runners found on log-heads, not on modern dry flow manifolds. Jeff is also correct about the other things he lists, which is what I had in mind with my comment above about things "that have little or nothing to do with what you are asking".

Keep thinking outside the box, Slade! It informs and motivates the rest of us. And for what it's worth, I think you'll have great success with the Ozzy manifold. Be sure to check out the MegaSquirt EFI for your project. Even if you are like me and a complete idi0t when it comes to electronics, you can buy one off eBay all assembled and tested for about the same price as a used OEM ECU, and it'll be infinitely better suited to your engine. That's what I'm planning to do for mine.

Cheers! :D
 
Nice thing is Big Al is only about 20 minutes from me...he's good at electronics. I think I may go with Holley's Commander system, but I'm still researching that part. I've got another intake manifold coming. It's going to be interesting...and just part of my system. Think Turbo with MPFI on a 200...muhahahahahaha :eek: :eek: :eek:

I just keep looking at the left over turd heads I have in my garage and wondering if there is something I can do with them besides practice welding.

As far as the manifolds. Is it a safe assumption that is an intake was designed for carbs, then it is a wet manifold?

I'm hoping to have the MPFI up and running by this time next year hopefully with the turbo installed as well. But, I also have to upgrade my brakes, rear end, and T5 this winter (my old 4 cylinder one isn't doing so well and I don't know if it can hold up to a turbo).

Slade
 
I wouldn't touch ProJection with a 10 foot poll on a 302.

That system is only slightly better then a carb, and that's from people that work at Holley. the Commander 950 system is much better, and does come as a TBI.

But, TBI suffers problems as being just an electronic feedback carb and doesn't have a lot of the benefits of MPFI. I may run TBI temporarily while I work out some of the manifold issues, but the end goal is MPFI.

Slade
 
Good to know - i will stay away form that. It's too bad really cause it LOOKS like a good setup but in reallity i guess it is just a glorified carb

John
 
Don't get me wrong, projection is okay...just my opinion is if you are going to do it, get the best and most up to date.

Slade
 
If you go over some old posts, you'll see how simple to inject the log is. There is a way of making it work, but you have to make a line of best fit for the injectors. The front runner dips at 25 degrees, the rear at about 40. So if you settle on a 30 degree dip, and follow the Hillborn and Offenhauser aproach, you can stick with the existing exhast ports, do some cutting, and end up with an EFI system which uses most of the existing log as possible, but has a single throttle body of a 5.0 or 4.9.

There is nothing hard about it. Use an extruded alloy fuel runner, and settle on a Megqsquirt, SDS, or Delco EFI control unit.

Once you sit there looking, a big bolt of lightnening will hit, the :idea: will strike, and you'll see that the log is an assett, not a disadvantage.

The Datsun/Nissan L26/L28 efi intake won't fit the log head easily, as the bore spacing is 3.8125", not 4.08". So there is about 650 thou offset at number one and six runner, while the centre runners are out due the the phasing of the wider spacing of the centre runers on the little Ford I6.

With some work, the manifold and injection runners could work as the Nissan 280ZX casting is quite thick.

Just my 50 cents. I've almost done my EFI log mock-up.
 
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