Room for injectors in a log manifold?

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Wesman07
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Room for injectors in a log manifold?

Post #1 by Wesman07 » Fri Jan 12, 2018 8:03 pm

So I there is something about the log manifolds that it like. It's just simple and compact. I also like fuel injection for daily drivers.

Is there enough room to fit injectors in a log manifold with a reasonable size throttle body? Or is throttle body injection the only option?
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Re: Room for injectors in a log manifold?

Post #2 by pmuller9 » Fri Jan 12, 2018 10:21 pm

Take a close look at installing the injectors in the side of the log where they would point directly into each intake runner leading into the head port.
You would drill and tap for a threaded bung to hold the injectors.
It will be tight on both sides of the carburetor area but I think it is doable.

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Re: Room for injectors in a log manifold?

Post #3 by Wesman07 » Sat Jan 13, 2018 5:10 am

On the side? Not the top, like the efi manifold?
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Re: Room for injectors in a log manifold?

Post #4 by pmuller9 » Sat Jan 13, 2018 6:20 am

Top mounted injectors similar to the stock EFI would probably require a bung to be brazed in place because of the thin wall thickness.
If you go straight in from the side you might get away with just threading the hole for the injector bung.
The injectors would be shooting fuel into the ends of the runners which still works well.

In both case you still have to make your own fuel rail and figure out how to secure the rail to the manifold.
I'm assuming all stock carburetor log intake manifolds are cast iron?

If you're thinking about using the stock injector fuel rail, the injectors angle slightly to the side.
You might consider cutting the lower half of the stock EFI manifold short and welding on an aluminum log that has a larger inlet for the throttle body.
This way you can use the stock EFI fuel rail and mounts and still have the look of a log manifold.

Thoughts?

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Re: Room for injectors in a log manifold?

Post #5 by drag-200stang » Sat Jan 13, 2018 11:27 am

pmuller9 wrote:Take a close look at installing the injectors in the side of the log where they would point directly into each intake runner leading into the head port.
You would drill and tap for a threaded bung to hold the injectors.
It will be tight on both sides of the carburetor area but I think it is doable.

the problem with side location is header heat will be a big issue for the injectors..If you keep one air inlet , fuel for 2 and 5 will get blown down to 1 and 6, because of the velocity of the smaller log.
I will ttt what I am doing I am sure pic are gone..I put then in the runner down by the valve cover rail .It points at the front edge of the valve..I knew that I could break through so I epoxied the valve cover rail on the inside...I would not go this way again, I would mount an angled bung that could be bolted down using a gasket or o-ring , just up from the rail..the large logs are quite flat and all runners (ports) are the same angle and plane there..
I re read your post and I was thinking you meant side of the log , I will leave my post for anyone thinking to put then in the exhaust side of the log.
I goofed up, this post is about the small six. not the big six :oops:
Last edited by drag-200stang on Sat Jan 13, 2018 10:18 pm, edited 3 times in total.
66 Mustang Coupe
200 turbo w/lenco 4-spd
stock adj. rockers, stock timing set, ARP studs
best 1/4 mile ET 9.85/best mph 139 on 8 lbs progressing to 15 lbs boost
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Re: Room for injectors in a log manifold?

Post #6 by pmuller9 » Sat Jan 13, 2018 12:30 pm

drag-200stang wrote:The problem with side location is If you keep one air inlet , fuel for 2 and 5 will get blown down to 1 and 6, because of the velocity of the smaller log.

Good point. Scratch the side location idea.

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Re: Room for injectors in a log manifold?

Post #7 by Wesman07 » Sat Jan 13, 2018 12:49 pm

These are all options to consider. I'm just brain storming. What I'm looking for is a simple design, and something that won't look out of place. To me, the efi manifold looks out of place.

I like the idea of the fi tech throttle bodies, but I feel it is a step backwards from multi port and I don't think the software is up to par with mega squirt. Then I started thinking manifolds with a throttle body and multiport inject run off of the stinger pimp. Minimal wiring, great software and I could still get most of the parts from any auto store or junk yard.
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Re: Room for injectors in a log manifold?

Post #8 by Wesman07 » Sat Jan 13, 2018 12:57 pm

Drag 200 stang- do you have any pictures of what you tried?

And thanks for the input
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Re: Room for injectors in a log manifold?

Post #9 by pmuller9 » Sat Jan 13, 2018 1:01 pm

I was thinking of only using 4 inches of the stock EFI runners out from the head. Injector bungs and fuel rail would be Done!
Weld on a square tube log giving some resemblance of the stock log.

Here is an example with a round tube log with side mount throttle body. You will need to be logged in to fordsix to see the pics.
Yours would be a square tube with top mount throttle bodies.
viewtopic.php?p=595689#p595689

Then you have the option of using three throttle bodies for better air distribution.
The throttle bodies could be three 1 bbl carbs for a cool looking Tri-Power set-up

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Re: Room for injectors in a log manifold?

Post #10 by Wesman07 » Sat Jan 13, 2018 2:38 pm

I like that. Any problem with a throttle body mounted in that location? I typically see side mounts with a tapered plenum.
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Re: Room for injectors in a log manifold?

Post #11 by bubba22349 » Sat Jan 13, 2018 6:00 pm

:hmmm: this is quite interesting! I wonder how close the port layout of a 200 / 250 log head is in comparison to that sawed off 300 EFI manifold's base? :nod:
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Re: Room for injectors in a log manifold?

Post #12 by drag-200stang » Sat Jan 13, 2018 10:10 pm

I fouled up, When you said log manifold my mind jumped to integral log small six..sorry, dis regard my earlier post. :oops:
66 Mustang Coupe
200 turbo w/lenco 4-spd
stock adj. rockers, stock timing set, ARP studs
best 1/4 mile ET 9.85/best mph 139 on 8 lbs progressing to 15 lbs boost
Went 9's when 10's was fast.

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Re: Room for injectors in a log manifold?

Post #13 by Wesman07 » Sat Jan 13, 2018 11:34 pm

I should take some measurement of my efi manifold and maybe I can find some measurements of the stock log manifold.

Is there an HD intake manifold?

Maybe working with an offenhouser or Clifford is an easier direction.

What I want to avoid is building a turbo motor that looks like it was hacked together.
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Re: Room for injectors in a log manifold?

Post #14 by pmuller9 » Sun Jan 14, 2018 6:55 am

I believe the Clifford has a boss for injector bungs.

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Re: Room for injectors in a log manifold?

Post #15 by Wesman07 » Sun Jan 14, 2018 1:59 pm

I've heard that, but didn't see any in the pictures that I looked up.

Would prefer a stock manifold though. Is there much of a loss if the injectors are sitting more up right? I would imagine fuel puddling would be less of an issue with sequencial injection.
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Re: Room for injectors in a log manifold?

Post #16 by pmuller9 » Sun Jan 14, 2018 7:03 pm

It is preferred to inject at the back of the valve head.
It cools the valve while helping to vaporize gasoline.
Will it make a difference? I don't know.

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Re: Room for injectors in a log manifold?

Post #17 by Wesman07 » Sun Jan 14, 2018 9:43 pm

Is there a noticeable difference in tbi to mpi?
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Re: Room for injectors in a log manifold?

Post #18 by pmuller9 » Sun Jan 14, 2018 10:11 pm

The Ford 300 log intake manifold works better with a certain amount of heat to keep fuel droplets suspended.
This also seems to be the case at low rpm with the aftermarket manifolds.
Unfortunately the heated air in the manifold is less dense, less power.

The mpi intake can operate cold, dense air, more power

If the TBI can do a better job at atomizing the fuel than the carb it's replacing and the manifold can be run cold then not much difference.

With a turbocharger heat is added to the incoming air under any boost condition.
The intercooler will play large part in manifold air temps.

The safe answer is MPI has the best chance of making more power.
I don't have a definitive answer. Too many variables.

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Re: Room for injectors in a log manifold?

Post #19 by Wesman07 » Mon Jan 15, 2018 9:40 pm

As always, thank you for your knowledge. I will have to pick up a log manifold and compare it to the injectors in the efi manifold. I think I can make something work well, without making it look like a hack job.
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Re: Room for injectors in a log manifold?

Post #20 by Wesman07 » Wed Jan 17, 2018 7:47 pm

On second thought, it might not be possible. It's hard to take a measurement with the motor together but the fuel rail is 4-5" off of the cylinder head. I think that would be real tight.
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