New intake- Pontiac w/ LSx upper
 

Take a peak at my new EFI Conversion manifold.
It’s an Offy 2x4 that Luhn Performance did some machining/welding/fitting on. Mark made some adapter plates, and built the fuel rail— they’re a great price, by the way!
Check out the video- I did a brief run down of intakes leading to this one:
https://youtu.be/BWACzcKYdso

You can contact Mark at http://www.luhnperformance.com/
for more info on getting your own done.
Tell him John sent ya!

Preview

Very cool! Great idea!

I was inspired by a post Tom V. did about 5-6 years ago when he was working at Ford. I really dug his intake and it got me to thinking... Then he mentioned Mark Luhn, so I made contact with him-- so glad I did!

Does anyone have an accurate CAD model of any Pontiac intake? Don't care which one, as long as the cylinder head/intake port location is correct.

I really enjoyed making use of the Nash/Warrior aluminum intake as a boosted EFI intake with the LS top Pieces (modified for the Nash/Warrior Dominator Carb spacing). The Dual Quad Offy intakes always worked well on the track, flowed well on the bench, and were fairly easy to acquire.

Mark @ Luhn does some nice Design & Machine work.

Tom V.

Glad I gave you the inspiration to get a intake from Mark.

actually I just found my blue prints!!!!:clap2:

have no digital copy as the laptop with all my solid works stuff (and my program maps)....is LOST somehow.:confused: can shoot a copy and post it. It is for my Torker II that I EFI'ed

https://nastyz28.com/data/xengallery...59e89fb133.jpg*

https://nastyz28.com/data/xengallery...5ce119dcf4.jpg*

https://nastyz28.com/data/xengallery...24297aed93.jpg*

circa 2008 when I made it all.......don't think there have been any revisions to port locations by Pontiac....lol

HOWEVER
my fuel rails sit LOW as I used the PICO (short) injectors

https://forums.maxperformanceinc.com...ictureid=14202
https://forums.maxperformanceinc.com...ictureid=14203

obvious note.....all metric dims (25.4 0r .03937 ..your choice.)

https://forums.maxperformanceinc.com...ictureid=14203

https://forums.maxperformanceinc.com...ictureid=14202

Sweet. Been talking about this for years.

First intake I converted was in '98, an HSD that I had bungs & stands made for, and rails. That was an Accel Gen 6 EFI setup. MARREN did the work.

Then did a Tomahawk, MARREN again did the bungs, stands, and rails for it.

Even had an Offy I was going to do, but there were few options for configs other than running 2 throttle bodies. When the modular tops came out, was disappointed I had already sold my Offy.


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Steve Grebeck was killed in march 2002. He welded the EFI bungs on my Warrior Intake about 4 years earlier so that would mean my EFI project for a Pontiac started about 1998.

Now I intake sat for several years on the shelf due to Grebeck's death then I had a fabrication shop in Livonia finish the intake and do the upper plenum design and fabrication.

I used years ago the Holley High Ram intake plenum top piece (with the carb mounting portion of the top machined off) and a custom Warrior intake plenum port pattern (Dominator) plate welded to the area machined off.

I also used a 105mm Throttle Body upper Plenum vs the 95mm plenum top (as I already had a 105mm Holley Throttle Body). A fun project, but $$$$.

Mark at Luhn Performance apparently has several OFFY intakes either machined or mostly machined.

Tom V.

Thanks for that! It's a good start. What I really need is the intake port locations in 3d space, or at least a distance from the centerpoints of, let's say, between two intake gasket-locating counterbores on opposite heads. Once I reverse-engineer a gasket I can then locate the ports in 3d space if I know how far apart they are.

I suppose it wouldn't be that difficult to put a manifold on a surface plate and with the help of a knee, use a height gage to get something accurate enough.

If anyone is interested in one, it looks like Mark at Luhn Perf. has an Offy 2x4 available.

The bit I don't like about the Offy 2x4 is the 'dog leg' in the ports, the air has to turn almost 90 degrees. When I reworked mine I cut the top of each port off and welded in a new roof so that the air had a straight shot at the head ports.

Typical method for measuring \-----------/

would be part sitting flat and use 2 dowels..... 0\-----------/0

with know diameters and measure over the outside then a little trig per the known angle (45)......onless you have a couple moldmaker ball-pins ;)
https://us.misumi-ec.com/vona2/detail/110300560910/
and a CMM.

Otherwise it's going to take you a minute to do all the set-ups accurately and then figuring per plane.

I can measure the width INSIDE where the injectors enter the runners....since my intake is on the shelf....to show how far "inside" the intake they are. Appears to by 285.600 mm CL ---> CL ....in width. but that does NOT give you "where" that is in relation to the intake ports

Why not use a gasket for rough measurements? You could use the gasket itself as a template and cut out some 1/4" plates on a CNC. Or even have someone do it for you.

If that's not good enough, get an old intake and cut off the end plates.

You can bolt the plates to heads that are mocked up on a block and get cross measurements. Or even build off the plates mocked on the heads/block.

You can use existing top plates to create a topper, and build intake tubes. Or get a Holley EFI ram and cut the legs off, and make new ones that line up with the head side plates.

Can even use carbon fiber and do pretty much anything you want.


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As for injector placement, you want the injector end pointing directly at the back of the intake valve. You can choose injectors with different spray patterns depending on desire.

Due to intake runner designs, etc, it is not always possible to lean the injector over far enough, so you can make up for that with different spray patterns. For example, if the runner has a hump in it, or a very tall ram style runner design, the rail may hit the runner or other area.

If you have room, and get creative, you can actually put the injectors on the opposite side of the runner, in the valley area. But that can make it tough to maintain. (injector replacement, etc)

When you think about TBI setups, the injectors are at the very beginning of the intake. Those type are usually a 'fan' or 'fog' pattern injector nozzle.




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I did a year and a half study on injector placement, at my job years ago, and
I will say that there is no IDEAL injector "Point" location for the spray based on that very accurate, engine dyno Research Study.

Way too many variables involved.

The key thing is that: depending on the speed of the air/fuel charge as it approaches the valve seat (engine rpm), the air flows differently around the
valve seat and into the chamber. That is why ports will have tumble which may change to swirl and vise versa depending on the head design.
A 4 valve head has much better control of the flow patterns into the combustion chamber/cylinder vs a 2 valve head.

That is why there are so many variables in 2 valve head design.
But I guess Generic Statements are as good as anything else in injector
placement and angle.

The reality is you would probably be with-in a couple of HP if the injector rails (from an end view) were vertical on the intake vs trying to get the injector pointed exactly at the back of the valve. If you were doing Emissions work, maybe you create 4 or 5 designs and see which one gives the lowest emissions for the EPA Testing.

Just my experience on this topic.

Tom V.

I would still think pointed down the port towards the valve would be better than pointing straight down at the floor of the runner, or at least that would be my line of thinking. Maybe a 45 degree 'lean', down the port even.

But suspect you're right about not much of a difference. I was parroting what Marren told me in previous conversations. Guess it's more of a general' or 'generic' statement as you mentioned Tom...

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If you are running in a water craft at a given fixed speed then you can design the fuel spray for spending most of the time at that engine rpm point.

Same deal with a Drag Race engine. Not the case with a Road Race Engine or a street driven application.

So you are correct, for Drag Racing pointing the injector at the center of the valve bowl might be better but cannot believe that anyone using a Offy dual quad intake is assuming max power and needs more than a simple vertical Injector Position.

Tom V.

I know how to measure the manifold using dowel pins; was just trying to save the 5 min setup time. You know, being lazy! But, I had forgotten about tooling balls. That's a great idea. Probably best to use a factory intake vs an old aftermarket one as hopefully they're machined more accurately-- but that's probably wishful thinking.

hahahah...then you trow i running a batch fire system.....where it gives 3 aquirts with the valve CLOSED.....

bigger issue of what size are the holes...I know all mine are for standard dowel sizes! still a PITA .. obviously work in machining?

I will add one piece of advice given to me long ago by a Chief Engineer:

"ONE PIECE OF DATA, TOM, IS WORTH MORE THAN 1000 OPINIONS.

Tom V.

Never thought about combining vectors for the injector nozzle spray. Kinda like compensating for windage at the gun range. The faster the intake port velocity the farther upstream it needs to point?

Are any of these up and running on engines? Do you know the runner length?

All of the Offy Manifolds have very short runner lengths.

They built the manifolds for easy installation.

Manifolds tune by harmonics. 1st harmonic length was long, like the old Chrysler
Cross Ram Intakes. See Picture below.

Other Runner Length manifolds were designed for racing speeds.

The Offy intakes fit that situation but are good because of the Injector Placement options, not the tuned length.

Tom V.

This is an illustration of what a 1st harmonic, 2nd harmonic, 3rd & 4th harmonic waves look like.

Tom V.

Just as an update I called Luhn about these intakes last week. Unfortunately they are waiting on some small parts to finish them up. Iirc he said he had several (6-7) very close to finished up. I called to inquire of the rpm range of the intake. He believes it will be great in the 1500-6500 rpm range with very strong torque production.