2 fuel injectors per cylinder

G

GFOLSOM

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My V12 (not 12V, but Vee-12 cylinders) had two spark plugs per cylinder.
...if you read my introduction a few months back, you'll see I'm working on converting a 27liter V12 rolls royce Meteor engine (post WWII transport engine) to run on diesel/jet fuel instead of gasoline...

Most all of the 4 stroke diesels around here have one injector mounted in the centerline of the cyliner. From what I've learned, there are only a few 2 stroke diesels that have two injectors in the cylinder mounted about 65-75% of the way out from the centerline and aimed toward the center, but with offset Beta angles to create swirl.

Our original idea was to use one injector in one of the old spark plug holes and put a glow plug in the other, now we are considering putting injectors in both locations to help us keep the injector size down around something purchaseable instead of truly custom machined.
(27L/12cyl=2.25L then 2.25/2injectors=1.125liter-cylinder per injector)
This would be about the same size requirement as a 6.75Liter 6 cylinder...

My question though is about trying to determine how much swirl to induce due to the angular offset of the injectors.

Based on the current construction of the engine and our planned modifications to the bottom end, we may be able to run something like 8-12psi boost from the turbos. (nothing like what most of you can run, but I can keep that up all the way to high altitudes!)

Thanks for any insight you have.
 
Sounds like it can work, but the big question is how are you gonna manage spray angle and get both patterns into the bowl?
 
Cool project! :Cheer:

Few ???

In light of the intended use, doesn't weight & max potential HP/CI make a Merlin more sensible?
Or are enough custom/aftermarket parts planned...

Since compression ignition is spec'd, my 1st question is what pistons are you using? Or is that one of the items still in the design phase...
Given the Meteor's massive cast pistons (3 compression rings & 2 oil control rings IIRC), no doubt any bowl geometry can be had, but why not go forged & use the rest of the bottom end's ability to handle 25psi forced induction-generated combustion pressure?
I mean, at least TIG-reweld the cast's machined bowls & cryo - 12psi is SO gasser! LOL

What fuel injection system is planned - that'll greatly affect your A/F homegenization strategy (assuming that's what you meant by "swirl" - don't think you'd want swirl in what I suspect is the application;))

I don't think beta injector angles are warranted, or beneficial - you've got 4 valves/cylinder, so don't think in 12V terms... in our shop I would spec this beast with indexed pairs of 8-hole asymmetric-flow re-entrant HPCR injectors - have to check for certain, but I imagine using the spark plug bore axes would work fine.
However, if it was my decision - I'd machine oblong bowls to synergize the injectors... should have plenty of material to work with and CCs won't be an issue since 6:1 C/R should dictate longer rod, lower pin height, etc. anyway.
That'd greatly reduce the required amount of orifice imbalance while using the bore to greater efficiency, and Somender grooves in the squish (assuming you can get to compression ratios featuring squish from a 6:1 foundation! :hehe:) could be added to fine-tune the trail-blazing injector scheme based on combustion pattern.
 
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Wow, awesome project:rockwoot:. Best of luck and cant wait to hear how it goes:pop:.
 
OK, don't forget, if you didn't know already, that a R/R Meteor is about 80% Merlin right out of the box. Except for the beefier lower engine block and the symmetric camshafts. There are additional accessory drives and a couple of things like that around, but the rotating gear is all Merlin and if you put them side by side it's real easy to see the heritage. As for application - you guessed it! When I purchase "Merlin" parts the P-51 guys jack up the price and I'm not rich. When I purchase "Meteor" parts, then people act normal. Meteors are basically a Merlin that was converted to life on the ground and then toughened up. They weight about 100lbs more than a Merlin when both are stock, but I designed a tuned port aluminum tube intake and am working on the exhaust too. The entire magneto system will go away and be replaced by a couple of mechanical fuel pumps similar to P7100s on steroids with a idler gear that will enable injection timing on the mechanical system. (as much as I'd like to to CR, it's too risky to fully rely on electronics) The original fuel pumps can go away too, along with the high priced avgas that went in them. I'll be adding 2 additional cross bolts to each of the 7 main caps so they'll have 6 bolts holding them and also adding the typical steel plates to each side of the lower block where the cross bolts come through. Merlins with this work done can run upwards of 100in-Hg at over 4000RPM for 20 minutes (that is, of course, after flying all the way across the country to Reno NV.)

The connecting rods are coming out of an allison V1710 and the pistons are all custom machined. I downloaded a free diesel engine design program from some Russian university (please don't dog me on the politics, I'm a True blood U.S. Navy brat) that really has taught me a lot about CI. (Diesel-RK Net) I am working toward a compression ratio of about 15:1, which is why we think we can dispense with the glow plugs. I have been lurking around this forum reading until my eyes hurt and learning a bunch from you guys - thanks. I have sketched up a shallow bowl STEEL piston with three rings in the upper region, and none down low on the skirt, more like ya'lls more modern racing/pulling pistons. This current sketch has the bowl set at 4.75" x .40" deep at the center. .25" radius on the cone point to .60" deep at the outer walls with a .25" radius there also. The compression walls have a 5deg. reentrant angle. - Anyway that's the sketch for now.
This engine MUST run at ~80% throttle for up to 4 hours at a time and be able to run at 100% for upwards of 15-20 minutes during climb. Refuel and do it all again...

Concerning Injector spray angle...
I haven't really figured out how to limit the Beta angle, whether it's right toward the centerline or off axis, but I currently sketched up a new nose/tip for a Cummins injector with 5 holes spaced 5 degrees apart and pointed 13deg. down. I am still learning about fuel timing and trying to keep the fuel in the bowl while the piston is coming up, so I may have missed the number, but I'm not machining anything yet, so it's a place holder for now. I don't know how to control the clocking angle of the ports since the fuel injector is simply screwed in to the old spark plug ports. I'm going to have to create some sort of clocking key (any ideas?)

Am I on the right track with 2 injectors, or is there any reason not to do that?
 
Sure, the Meteor started out as a low-cost, blower-less version of the Merlin spec'd for Brit tanks... still awesome to behold.
Who couldn't love 48 valves that big? :woohoo:

Figured it was for NCAR - I bet Dad never missed a single race while he was Reno Air's Chief Pilot... his last year there he got to watch my brother's Hornet do the Blue Angel routine for the event - Go Navy!

I could brainstorm for hours on this...

Why aren't you targeting higher power production?
(seems quite a bit will be left on the table)

A link to the rules you're subject to would be helpful.
 
BTW, Allisons were the original gasoline powered engine in P40s during WWII but most of them got destroyed by the drag-boat racers in the 60's and 70's so they cost more the Merlins do nowadays. There were two versions of the P40 with Merlins sold to Britian. It was easier for them to maintain that engine, since several other British birds used the Merlin.
The Meteor stayed in production up until 1991 in ground equipment so the blocks are readily available and cheap when purchased in Europe (~$9k instead of the ~$50K for Allisons) That's why we're using the Rolls Royce motor.
We've already got them running on gasoline, but that has the problem of avgas availability. You may know that avgas (100LL) is currently about the only fuel in the world that still uses lead and there is a big push to switch all of the GA airplanes (from Cessnas to Gulfstreams) to an unleaded fuel. The problem is 1: octane and 2: high altitude flash point.
Vapor lock is REALLY bad!
That's what started this whole insane idea of switching over to the diesel cycle with Jet-A, which is always readily available and actually cheaper than avgas. The increased fuel mileage will be a nicety.

..and oh yes: I love the smell of Jet fuel in the morning...:doh:
 
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