2.4 with an SSD and a 45DCOE
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Thread: 2.4 with an SSD and a 45DCOE

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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    2.4 with an SSD and a 45DCOE

    It's nearing the time for me to install the engine in my GTX car and, as usual, my original plans have changed. I have decided that the challenges of jetting my chromed 40DCOE on this slightly too large engine were beyond my patience level. I had contacted and ordered jets for the 40-on-a-2.4 from two of among the most high profile Weber SD "experts" in the country and gotten wildly different jets from them. Also, I think my chromed 40, that was originally intended for a Harley, has deliberately weakened throttle springs, so that the motorcycle handgrip throttle could operate it easier. It's just a guess.

    So, screw it, boldly going where no Opeler seems to have gone before by putting a 40 on a 2.4 and coupling with that my only using ONE DCOE through an SSD manifold made this whole thing way over my head.

    So I bought a brand new 45 DCOE, the supposedly appropriate sized carb for normal driving of my stock 2.4. As you may recall, RallyBob modified the support and bolting of my Single Side Draft manifold to work on a 2.4 and hogged it out and ported it a bit for the larger 2.4. The Midikit SSD was intended for a 1.9/2.0 headed engine.

    And, thus, this thread's big question:
    What sort of jetting scenario should I start the process of dialing in the jetting on this engine?


    I recall one of our more obscure members making a post about his 2.4/SSD/45 engine and I'm wondering if he'll pop up and reveal the jetting he ended up using?


    Mike's article in The Blitz which just arrived today has got me planning on buying an A/F meter and maybe one of those jet assortment packs that I think are available. As an added benefit, my engine came with the stock 2.4 exhaust manifold, which has the bung for the A/F sensor. Bob fixed that up, too, and made me a custom 2.25" headpipe for my manifold and exhaust for a GT. A little shiny silver jet coating of both items tops it all off.

    So, assuming I get some jets, a decent meter, and figure out how to fit the meter's sensor to fit my manifold or wire the oem sensor my manifold came with to the A/F meter, I should be well set up to tune this stock, used, engine for normal driving use.

    Jetting suggestions?

    Meter suggestions?

    Wiring the oem sensor to a gauge in my car suggestions?

    Last edited by The Scifi Guy; 06-29-2015 at 05:56 PM.
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    2000 Post Club GeorgeOpel's Avatar
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    Gordon any idea where is the best place to get a 2.4L Opel engine? What do they sell for? Thanks

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    Teamwork:Go for the GTX

    Ha ha
    My suggestion is simple.

    1.) Fit all together in the GTX.
    2.) Try to start with the sizes are inside the carb.
    3.) Rent a trailer and bring the GTX to Rally Bob for fine tune up.
    4.)You can drive the GTX with fun

    Norbert
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    7,000 Post Club My location wrench459's Avatar
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    AEM inline controller is about the cheapest way to go.
    After a few hours on the dyno...your dialed-in.

    Si vis pacem, para bellum "If you want peace, prepare for war"

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    Project 1450 supporter... Site Supporter My location RallyBob's Avatar
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    I'd probably run 38 mm venturies in a 45 DCOE on your 2.4. It's a big engine.

    Based on that, a good baseline main jet size is 150 or 155.
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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Thank you for your help so far gentlemen!


    George, my 2.4 engine acquistion is a little bit different than most folks' path towards getting one. In a nut shell, I was wanting to buy a rebuilt 2.0 from OGTS, but they recently removed a 2.4 from a customer's car and offered to sell it to me used and unrebuilt for roughly the same price as the spiffy new 2.0. It was said to have excellent compression(165) across all the cylinders. So, I agreed to the deal and threw in a bunch more cash to have them regasket it, swap a steel GT pan onto it, clean it up and paint it yella.

    Normally you buy a 2.4 through OGTS and have to rebuild and gasket and configure it for a GT and all sorts of sometimes challenging and expensive parts gathering and modifying, depending on what your plans are for the engine. My "plans" are well off the normally trodden path, so I've got a heap of money invested in this. Well over $6000 with chromy bits, custom made widgets, misfires and mispurchases, and a screw up or two on my part.

    You might be able to get a base long block, without the FI that orignally fed the engine, for $3000-$4000, then plan on spending another $1000-$2000+ to get it running reliably somewhere close to it's potential.

    We're all relative rookies at this 2.2/2.4 engine stuff, they're relatively new engines to the American Opel scene. Yeah, they've been available for 20 years but few people have them and knowledge about how to set them up in various configurations is thin. OGTS is making great strides in trying to make these easier for knuckleheads like me to get running.
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    7,000 Post Club My location wrench459's Avatar
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    The 2.4l combo is a cluster at its best.
    I would go with the three inch stroker aka 2.2.
    The 2.2 will give you a better R/S ratio this means that it'll rev without parts flying out
    the hood.....
    2.4l are best known for bottom end TQ
    Not to say that you can't build a 2.7 to rev like a bat-out-of-hell
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    Si vis pacem, para bellum "If you want peace, prepare for war"

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    Is the engine with the front oil pan drip?
    Without disclosing the political details, I guess the problem has been resolved?

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    2000 Post Club GeorgeOpel's Avatar
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    Quote Originally Posted by Lindsay View Post
    Is the engine with the front oil pan drip?
    Without disclosing the political details, I guess the problem has been resolved?
    Can you fit a single side draft ( or dual) instead of FI?

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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Quote Originally Posted by Lindsay View Post
    Is the engine with the front oil pan drip?
    Without disclosing the political details, I guess the problem has been resolved?
    Well, no "resolution" yet, other than that I have to regasket the engine and while doing so figure out why the leak occured. It's extremely likely I over tightened the two front bolts attaching my tranny coolant lines to them and that warped the pan. Then there was the evidence that the head/block union was leaking. Were the head bolts tightened properly? Won't know till I take it apart. I've been given a new set of the best gaskets and I have two aluminum oil pans to try out to see if I can get away with using them and not have the crank bolts hit it.

    I sure wish that Bob would modify a few aluminum pans for 2.4 use.

    Today's quest is to find those formulas for calculating jet sizes on the Internet. I found them one time and can't find them again. Start searchin' for me boys!




    Quote Originally Posted by GeorgeOpel View Post
    Can you fit a single side draft ( or dual) instead of FI?
    Yes you can put any carb set up you want on an engine, it's just a matter of finding or making the parts to do it.

    Heck, Dan don't use no carbs or FI or nothin'! He's got some gee whiz set up where he squirts gas into the ports with a Windex bottle!

    Cue that cool video of Dan's open port engine running.........
    Last edited by The Scifi Guy; 06-30-2015 at 05:36 AM.
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    Project 1450 supporter... Site Supporter My location RallyBob's Avatar
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    Quote Originally Posted by The Scifi Guy View Post

    I sure wish that Bob would modify a few aluminum pans for 2.4 use.

    Today's quest is to find those formulas for calculating jet sizes on the Internet. I found them one time and can't find them again. Start searchin' for me boys!
    Modifying aluminum Opel oil pans is an exercise in futility. I'm pretty patient, but welding those pans tests my limits. I built a custom deep sump aluminum pan for Roger Wilson in 2010, and swore I'd never weld another aluminum pan after that. I guess I was lying to myself, because this past winter I built a dry sump oil pan using an Opel aluminum pan as the starting point. I washed it, then had a shop hot tank it, then washed it again, then had it baked in an oven at 550 degrees for an hour, then glassbeaded it, then washed it again (hot soapy water first, then acetone). It still bled out oil like crazy. It took three full passes with the welder to get a decent seam between the old oil soaked metal and the new metal.

    As far as the jetting, you need to choose the venturi size based on the engine displacement and the rpms it will run at. Then you choose the main jet based on the venturi size. The starting point is typically 4 times the size of the venturi. So with a 38 mm venturi like I recommended, your starting main jet size is 38 x 4 = 152. That's your baseline.

    If you keep small venturies in there it'll be a tractor of an engine! I'd be surprised if it revved over 5000 rpms.
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    ggl
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    Quote Originally Posted by wrench459 View Post
    The 2.4l combo is a cluster at its best.
    I would go with the three inch stroker aka 2.2.
    The 2.2 will give you a better R/S ratio this means that it'll rev without parts flying out
    the hood.....
    2.4l are best known for bottom end TQ
    Not to say that you can't build a 2.7 to rev like a bat-out-of-hell
    Revs are over rated !

    (says the guy with an engine that will self destruct at 6200 rpm)
    "I hate RallyBob"


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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Thanks for the further suggestions Bob!

    Yeah, you've said before that the oil-in-the-aluminum was the problem with modifying them.

    But, it never hurts to keep bitchin' and whinin', though! Maybe I'll catch you on a REALLY good day and talk you into carving me an oil pan out of a giant billet of aluminum!


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    I know the barn doors are now closed off and all, with the DCOE's gone, but your journey in installing those DCOE's was an interesting, fun and informative one. I wish you had stayed the course there....... As an avid reader to that thread, it was a treat to see the latest stuff coming in from the outside suppliers, to see it come together. It had me contemplating that set up as well, but I have no 2.4 in my immediate future to top it off with...

    Thinking Nascar and restrictor plate racing at Daytona and Talladega here; yep, she's a street car with real world speed limits to stick to; that's a given. A weekend warrior and show car at that. But I think you've strangled the true potential of the 2.4 by restricting it with a single DCOE, no matter how big the barrels or venturi's...... Of course, she'll go down the road just fine like any other two barreled carb car and she'll get you a suspended license just as quickly as if you had twin dual throats on her.

    Please take this as non-solicited, friendly and constructive observations and nothing more! I'd equate this set up as a Nascar Daytona configuration set up to run on the Road Course at Sonoma..... a big block LS-6 Corvette motor with it's big Holley Dual Pump carb lifted off and a 325 CFM 2 barrel put in it's place.

    As I too have that Midi Kit manifold like yours, Gordo, I will follow this thread with interest to see what combination you ultimately come up with. This is the great thing about this Opel community, sharing info freely among others....

    Mike
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    Just Some Dude in Jersey My location The Scifi Guy's Avatar
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    Based on my limited, no prior experience, complete novice, research that I've done on side drafts, there shouldn't be a big difference between dual and single side draft performance and function. That's assuming that the shared plenum and the bent, rather than straight, path to the ports of an SSD has a minimal effect. Apparently it's all about pulses of vacuum from the cylinders initiating the sequence of events that make the carb(s) squirt the right amount of gas into the air stream passing through them.

    In a normal side draft set up, you dedicate one carb barrel exclusively to one cylinder, no shared plenum as with the typical Weber down draft set up. Each carb has two barrels, so one side draft for every two cylinders. Each barrel acts as an individual carburetor. The two barrels/carbs share the single fuel bowl and both throttles are locked together. I think that is all the two barrels share with each other.

    With an SSD, you essentially create something like a sideways mounted Weber 38, in which two barrels feed into a common plenum to feed 4 cylinders. Like a side draft, both throttles of a 38 are locked together and open simultaneously. The vacuum pulses coming from the cylinders on their individual intake strokes affect both barrels of the side draft at the same time, rather than one barrel only responding to the demands of one dedicated cylinder, as with the normal usage of side draft where one barrel only services one cylinder.

    So, theoretically, when compared to the individual, dedicated, barrels of a typical dual side draft set up, each barrel of a single side draft, feeding a common plenum, that services 4 cylinders, would have to respond to 4 times as many pulses of vacuum for a given rpm, but 1/2 the volume of air, since you have two barrels servicing each vacuum pulse.


    What does all this mean?


    I don't have a friggin' clue!


    Last edited by The Scifi Guy; 06-30-2015 at 04:22 PM.

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    Well said! Your descriptions took me back to working on the old OMC outboard motors, 2-3-4 carb set ups where it was critical for all carbs to be opening their throttle plates at the same time, feeding all cylinders the same amount of fuel at the same exact moment..... The procedure was termed Synch and Link, for obvious reasons. Been so long removed from that stuff, I forgot pretty much all of that info. Use it or lose it, that knowledge..... The EFI fans will chuckle over this synchronization stuff, with their sensors and inputs telling the throttle body(s) what to do... Have you ever considered the EFI route for the GTX?

    No, I think you've got it down. I look forward to stealing, er, gleaning () your ideas when you come to your conclusions as per jets, etc; on my own project to come in the coming future! Hope all is well there on the banks of the Big Muddy, Cooper River! Take care.

    Mike
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    7,000 Post Club My location wrench459's Avatar
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    Knowing how Gordo likes to keep us in a major state of confusion.

    The EFI guys still looks at the kPa readings.

    99-100 is ok for N/A engines.
    150 it's in limp-in mode :-)
    200 kPa....now your starting to get somewhere
    300 Rock-and-Roll

    Si vis pacem, para bellum "If you want peace, prepare for war"

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    ggl
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    Quote Originally Posted by The Scifi Guy View Post
    What does all this mean?


    I don't have a friggin' clue!


    Ok ....

    You're correct in that a DCOE is 2 carbs sharing a fuel bowl and because they use a common throttle shaft they're always in sync. Always being in sync isn't necessarily the best idea because individual cylinders' need for air isn't always 100% identical, as a result there was a version of the Solex ADDHE, which is Solex' version of the DCOE style carb, where the throttle shaft was split and you could adjust them separately. It's the only place I've seen that so we'll just say it's could be handy sometimes but not worth the trouble/cost

    You're also correct in that a carb can flow more air when it's feeding more than one cylinder as the pulses even out and it becomes closer to a constant air stream, as if you hooked it up to a flow bench

    So, what happens when you bolt a DCOE type carb to a plenum take intake ?

    1. You lose the straight and short path from the throttle plate to the intake valve

    This means weaker throttle response and because the "signal" is now weaker, the pulses are less pronounced as we mentioned above, fuel metering could be suffering and we're most likely losing some torque at lower revs.

    Power at higher revs may not be suffering (much) because as we also mentioned above the air flow goes up and the theoretical max flow of the carb is higher in this configuration

    One of the major advantages of the DCOE style carb is that the fuel nozzle sits in the center of the air stream and gives better fuel atomization and a very even distribution of fuel particles in the fuel/air mix. With a nice and straight path to the combustion chamber, aside from having to make a turn at the inlet valve, this means that the mixture is very homogeneous when it arrives at it's final destination

    In the case of the SSD intake we're introducing some very sharp bends, fuel droplets are heavier than air and doesn't like to turn so the fuel distribution in the mixture will no longer be as even.

    2. You lose the individual runners

    We've already mentioned the weaker pulses but we're also introducing runners of unequal length and that means the pulses won't be evenly spaced.

    Because of the unequal length runners and because the turns aren't equally sharp you're likely to experience "charge robbing" where some cylinder are better fed than other's because they have a better path to the plenum, it would take a seriously well designed intake for this not to take place and given that the reason for the SSD's existence in the first place is to reduce cost and save space ....

    It's not just about how much mixture you can deliver, it's also about the quality of the mixture and it's distribution between the cylinders to ensure that all cylinders are contributing as much as possible.

    It's also more difficult to jet properly because you have to cater to the cylinders who are receiving the weakest mixture to prevent an overly lean condition and as a result the other cylinders will most likely be running a but rich, reducing performance a little as well as increasing fuel consumption

    So, will a DCOE work in a SSD setup, of course it will, it's been used like that almost as long as it's been used in DSD setups, and beyond, but it won't do it *quite* as well and your are giving up something when you do. If it worked just as well Weber could not have sold them in their intended configuration for 60 years as the news would have been out long ago

    Does all this matter, probably not. A friend of mine ran a SSD setup on his Ascona for a couple of years, a Solex 45 on a mild 2.0, and he was quite happy with it and it was still on the car when he sold it if I remember correctly

    Btw, if you have problem wrapping your head around this stuff try imagining a V8 and it's intake manifold with pulses arriving from everywhere ..... it's enough to give you a migraine attack
    "I hate RallyBob"


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    Would a 2.2L be better? Cheaper?

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    now hes trolling the one guy that shows him love. it has officially run its course.
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