Will a M116 4.2 intake manifold fit a M116 3.5

[Tony H]

Might seem like a silly question at first. I'm building my "iron block" 5.6 project but I don't want to run a new engine with an unknown ignition/FI system since I am using Megasquirt/EDIS. So my idea was to first install my old 3.5 and get it running well on the new FI/Ignition then transfer it to the 5.6. It would be close enough to run until I could get it dialed in. The 3.5 D-jet manifold requires different pintle caps so I wanted to use the same style intake manifold as the 5.6 so the injectors would fit. I think the alum and iron block M116 have the same block height so it seems like it would work.

[Frank Reiner]

Tony,

I think you'll be correct on block height, but would want to examine the match of the later manifold to the early heads. There may be idle air passages in the 4.2 manifold that could leak (or they could be plugged).
Do you have a manifold or gaskets from a 5.6? The head face of both of the alum. engine manifolds should be the same, although the width is different.

[Tony H]

I do have 5.6 gaskets-good idea-I will check tonight. The manifold is cheap at the Pick n Pull but getting it out will take a bit. When I got my 5.6manifold at the PNP a bolt broke off and it was a real pain. Bolts seem to stick/strip in the aluminum engines a lot more than the iron engines.

[GGR]

If you want to use Megasquirt you should use a D-Jet manifold as it was designed for EFI. The K-jet is of a poor design for EFI. I did fit a 4.5 D-jet manifold on my 5.0 M117, it works great!.

[Frank Reiner]

GGR:

Originally Posted by GGR

If you want to use Megasquirt you should use a D-Jet manifold as it was designed for EFI. The K-jet is of a poor design for EFI.

Would you be so good as to share with all of us your insights and knowledge on the subject of intake manifold design, so that we may become wiser, and better understand the subtle differences that make a K-jet manifold so ill suited for use with pulsed injection?

[GGR]

Originally Posted by Frank Reiner

GGR:
Would you be so good as to share with all of us your insights and knowledge on the subject of intake manifold design, so that we may become wiser, and better understand the subtle differences that make a K-jet manifold so ill suited for use with pulsed injection?

Why that tone?

A few years ago, I did Megasquirt an early euro 5.0 M117 originally fitted with a K-jet CIS. In the process, I did some reading about EFI, Intake manifolds etc. and my conclusion was that the D-jet manifold was better suited for my application for a number of reasons related to performance, parts availability, work involved and costs. I'm no engineer, so this is empirical, but 3 years and 60.000 miles later I'm very happy with the results in terms of performance and reliability.

The D-jet design has its throttle body in the center of the plenum which according to my readings ensures a better flux distribution. In addition, the shape of the air filter housing around the TB also acts as a giant venturi which accelerates air flux straight down the center of the plenum.

It's a near direct fit (I believe 100% direct fit in Tony's case) and allows to re-use most of the D-jet hardware such as injectors, fuel rails etc. Parts are easily available in many junk yards.

The K-jet system is designed around the need for an air plate sensor. Once you've taken it out, air flow through the ruins of the K-jet system is less than ideal and results in less flux acceleration. TB being in the front, air distribution is also less ideal. If you use a later K-jet manifold, you also have to deal with these plastic pipes between the injectors and the heads which put EFI injectors nozzles in a non ideal position given their spray pattern (too high). If you take these plastic pipes out, then you have to sort out an idle system. Finally, the diameter of the runners on the 5.6 manifold is 41mm, and only 39mm on the 4.5 heads which I believe Tony H is using. So there will be some porting needed on the heads so as not to end up with turbulences at the junction. If one really wants to use a K-jet manifold on this application, the early 4.5 is better adapted as it will save the idle and port diameter problem. In the end, it will work, but it will be more work and performance will be less than with a D-jet manifold. So why bother, when the D-jet manifold is a straight fit? This also allows to save a lot of work, time and money compared with adapting different injectors and fabricating rails.

[Tony H]

Sorry-I did not mean for this to be controversial. I am planning my project around 5.6 heads so that’s why the 5.6 intake. I believe I have resolved all the issues around using them on an iron block engine. Back to my original point-I want to get my new fuel/ignition dialed in before I use it on a new engine so I want to use my 3.5(well broken in) as a test bed for the Megasquirt/EDIS and then transfer it to the new 5.6. Since injectors that fit the Djet 3.5 manifold won’t fit the 5.6 manifold I wanted to put a Kjet manifold on the 3.5. Ford injectors fit without modification and they are Inexpensive and plentiful in a variety of capacities. Thanks to all for the input.

[GGR]

Originally Posted by Tony H

Sorry-I did not mean for this to be controversial. I am planning my project around 5.6 heads so that’s why the 5.6 intake. I believe I have resolved all the issues around using them on an iron block engine. Back to my original point-I want to get my new fuel/ignition dialed in before I use it on a new engine so I want to use my 3.5(well broken in) as a test bed for the Megasquirt/EDIS and then transfer it to the new 5.6. Since injectors that fit the Djet 3.5 manifold won’t fit the 5.6 manifold I wanted to put a Kjet manifold on the 3.5. Ford injectors fit without modification and they are Inexpensive and plentiful in a variety of capacities. Thanks to all for the input.

Tony, there is surely nothing controversial in your original question. I've just been surprised by Frank's tone over a simple advise I was giving you out of my own experience.

the injectors are in the heads, not in the manifold. And the D-jet injectors do fit in the heads (mine did). Apart from the hose top, D-jet and Ford injectors are of a similar shape at the bottom end. Are you keeping the black idle pipes? If not, have you thought of an idle system? The EGR port in the plenum could be used for that effect.

Just that you know, the 4.5 D-jet manifold will fit on the 5.6 heads. You will need to grind a bit where the injectors collars bolt on as the injectors will sit a few mm lower in the heads. This is what I did. And it will be closer to original, both in concept and looks, which if I remember well is also the reason why you're keeping an iron block instead of going with a 5.6 engine. If you go with a D-jet manifold, you will have to consider porting the runners where they mate with the head, from 39 to 41mm diameter or so. The TB on the D-jet is 65mm diameter instead of 70mm on the 5.6. 65mm is good for at least 300 hp (that's what my engine delivers) even if the calculator on the MS website says you need bigger for 300hp. I think the difference here is made by that venturi shaped air cleaner housing base which accelerates air flux. That set-up may be good for more, but I don't know by how much. In my case it is not restrictive as map is reading very close to 100% (no vacuum in the plenum) at WOT and max rpm. There would be some vacuum if the set-up was restrictive.

In any case, I'm not trying to convince you to go a different way, just sharing my experience so that you can choose among various options.

[vandor]

GGR,

>65mm is good for at least 300 hp (that's what my engine delivers)

May I ask what mods other the MS did you do to achieve that?
Thanks,

[GGR]

Originally Posted by vandor

GGR,

>65mm is good for at least 300 hp (that's what my engine delivers)

May I ask what mods other the MS did you do to achieve that?
Thanks,

More exactly, 254hp DIN were measured at the rear wheels, which translates into 300hp DIN for the engine (with manual transmission) according to an online conversion site.

My engine is an early euro 5.0L out of a 450SLC 5.0 which develops 241hp DIN in stock form. I have kept the long block stock with 8.8:1 CR and an estimated 200.000 miles on it when dynoed. I have retained the tri-Y exhaust system that was on the 450SLC 5.0. I have fitted the engine with a pair of AMG 50.1 camshafts with solid lifters, the D-jet intake and Megasquirt which controls injection and EDIS wasted spark ignition.

As a reference, back in the day, AMG reported 276hp DIN on that same engine, with a bump from 8.8 to 9.2 CR, heads ported from 39 to 41mm, bigger intake valves and the same 50.1 AMG camshafts with solid lifters. My engine makes 24 more hp without all these changes apart from the camshafts. Megasquirt is certainly a good part of it, but I think the D-jet manifold is also playing a role. However, some caution should be used by comparing hp figures as they can vary depending on dynos, formulas (ancillaries taken into account or not), and I don't have all the details. But given the mileage on my long block, its stock form, and driving comparison with some cars fitted with AMG modified engines , I believe the package I have used is quite a good one, especially when it comes to the "work + cost = results" equation.

[Strife]

I have a 380SL engine out, and I've been considering Megasquirt for future use. The later intake design seems to have a lot of consideration for the offset throttle body (the lower part of the intake would seem to help in evening things out), so I don't know if this would really be "worse" than the older intake, although it certainly is more of a pain, being so low. Other Megasquirt-related problems with the newer manifold I see are that the posts for the mechanical FI would definitely need to be ground down, and the rails will interfere with the throttle and the engine hoisting pieces (obviously important, if you intend to pull the engine). I have a 380 (aluminum 116) and 560 (aluminum 117) engine out and the differences are startling - the 560 manifold is a LOT larger.

[Tomguy]

I still want to know if an m119 intake would fit, or could be made to fit. That's an interesting concept to me

[vandor]

Thanks GGR! I assume the 50.1 AMG camshafts are impossible to find?
Did you notice any drop in low end torque with them?
Thanks,

[GGR]

At the beginning I had a bit of trouble at lower rpm due to backflow. The reason is most seemingly my rather low CR. I advanced the camshafts by a few degrees and it helped a lot. I have lost a tad bit at max rpm in doing so. However this being a daily driver, I am rarely at max rpm, and I enjoy the gained driveability very much. Engine now is running very smoothly at all rpm, thanks to the 100% EFI and ignition tuneability. It is difficult to say if I lost low end torque because I converted to a manual transmission at the same time. I think I did, however I think it is preferable for the life of the manual trans. All in all I like the compromise I reached. Very driveable and trouble free.

I sent you a PM regarding the camshafts.

[Tony H]

I am aware of 2 people producing the AMG camshafts-$650 a pair for reground and $1100 for ones made from new blanks(the base circle is not cut)