FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: funsummer on July 07, 2017, 05:39:22 PM
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eBay got the better of me while working out at sea!
Purchased 4 split dominators for a great price. Have a fresh built 390 stroker with 4.250 rpm steel crank.
Ordered new flat top pistons from Barry to raise comp at 10.7 with unshaved heads.
Question is could the Carbs be mounted on individual runner intake similar to webers?
Or maybe a tripower style arrangement if I must keep them progressive with a plenum?
Limiting factor on rpm as I see it will be the t@d street rockers.
If I go to a solid or solid roller camshaft what is max rpm that I can reliably achieve with my setup?
Understand that cylinder port flow will be critical to the max hp achieved so will be getting the kc stage 2 heads flowed and hopefully improved locally.
Any advise on the intake setup?
What camshaft would be recommended if individual runners are used not used?
Will reversion be an issue?
Thanks
Joel
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Carbs are going to want a plenum.
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Scott I was thinking as there be a carby Venturi able to feed each port I might be able to run independent runners. Like the Weber carburettors do so successfully.
Is the reason I require a plenum due to using holleys?
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Just do this:
https://bangshift.com/bangshift1320/ooga-booga-intake-and-carbs-this-cfe-sheet-metal-intake-manifold-plumbed-for-nitrous-and-topped-with-split-dominators-rules/
;)
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That link has your standard pro stock sheet metal manifold.
Certainly effective but not at all what I am trying to achieve.
If I cannot run them on a short individual runners then I will look at a tri power intake with progressive linkage.
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Whit a IR carb intake system the carb venturi size is the problem "choke" it will take dual dominator's to feed a T/A Boss 302 producing
470 HP or so
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If you wanted to get creative, you could use one of Jay's adapters with a Bud Moore 351C maxi plenum intake, and make a custom top for it so that you mount a split Dommie over a 2-cylinder pair. :)
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How big are the throttle bores on those carbs? FYI a 48 IDA Weber setup has 48mm throttle bores, which is just under 2". When I dyno tested those, if I recall correctly I put in 45mm venturis to max out the airflow potential. They were pretty tough to beat up to 550 HP or so, but after that they fell off somewhat compared to the other intakes. I would say that whether or not you can make an IR intake work with those carbs will depend on the venturi size and your horsepower goals.
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Scott I was thinking as there be a carby Venturi able to feed each port I might be able to run independent runners. Like the Weber carburettors do so successfully.
Is the reason I require a plenum due to using holleys?
Above comments are correct...not near enough throttle bore dia. for IR. I also don't think the carb is designed to deal with the reversion like a Weber but that might be more a function of throttle bore dia. than actual design.
The original Weiand Pro Ram intake was designed to bolt a Holley Dominator right o top of the runners. In fact, it still has the same bolt pattern today. I forget who did the R&D (I think it was Smokey) but two Dominators on a SB Chev were not big enough for an IR appplication. Just food for thought. Ultimately they decided they needed a common plenum. Another point of reference...look at the size of the butterflys on your typical individual runner MFI set up. That'll give you a clue as to the demand of an IR intake design.
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Not that I feel like adding anything to the thread......
but where do you work offshore?
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Jay I have your intake book and studied the numbers, I am aiming at 600hp, the great results shown by the webbers were the reason I was interested in trying the IR manifold.
These carbs came off a 812 cube sonnys prostock engine and look to be heavily worked.
The throttle plates are 2.2" so I think they should flow enough for my use.
I was concerned they be way to big if used on a plenum hence suggestion of tripower.
Also why I was interested in cam specs as currently have a 232" @ .50 hydraulic roller on order and was thinking I need to go solid/ solid roller to get more rpm to utilise these carbs.
And if IR then options to reduce reversion.
I do have the reversion plates so that should help.
Love the look of webbers and thought this be a interesting and individual intake setup, and hopefully as successful as Weber IR.
Am in contact with CFM as carbs were produced by them.
Brent thanks for info will google that manifold you suggested tonight.
I am all ears. Jays intake was in my plan if I go IR.
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Brent, that box intake seems like it was before it's time, many new efi intakes employ the same long runners that cross over..
I like your suggestion but there is a budget and as soon as the words rare vintage and NASCAR or canam are put together it usually is well above my budget.
Definitely food for thought, I was thinking short runner as it be very direct and almost vertical inlet.
What are the gains/losses in having the longer runners? I have a bonnet with scoop so tunnel rams are not possible. Would more fuel fall out of suspension due to the long horizontal runner?
Drew, have pm you briefly before.
For everyone's info I am currently working for Mcdermott on a small vessel owned by solstad.
I am in itchys field off north Western Australia.
Few weeks ago I pulled in the mooring chains on the worlds heaviest semi sub platform.
Google Impex explorer, she a seriously large vessel.
3x 30 MW gas turbines I believe..
Not FE related but might interest some.
Joel
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If the carbs have a venturi diameter of 2.0" or so, the IR idea with those carbs might just work at a 600 HP level. Sure would be fun to try that; what a unique induction system that would be! Post some pictures and test results if you go forward with that.
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Jay,
Thanks for the input.
Posted looking for some feed back and input.
With all your intake experience if you think it's worth a go then that's reason enough for me to have a go at it.
What about camshaft specs to limit reversion?
Would cam suitable for webers be best place to start?
Joel
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Not to put a big damper on your idea, but even if the throttle bore and venturi size end up working out for you, you may very well find the metering blocks, air bleeds, etc. are no where near what your application needs, compared to what they where designed for. Carbs of that sort are pretty specifically designed for the combo. It's an interesting experiment though, let us know if you go forward.
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Kevin,
Agree totally about the carbs internal setup.
Hence why I have contacted the original carb supplier and will be seeking there advice on changes required.
It's certainly not going to be a simple bolt on part.
Will also be buying and reading a few carburettor books to really understand the reasoning and methodology behind recommend changes.
And also being able to give more detailed analysis of problems encountered.
Steep learning curve for sure, but something I am very interested in.
Appreciate your input
Joel
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You just have to keep an eye on the amount of overlap you have when you're working with individual runner setups. With a solid flat tappet or solid roller, you're in a better situation because there's less major intensity. In contrast, a lot of the hydraulic rollers we use have a really high advertised duration in comparison to the .050" duration, so you're already at a disadvantage with the amount of overlap that you have. That's why you see a lot of individual runner camshafts on a 112-114 LSA. You will need to keep velocity high at the carburetor, or else you'll see a little cloud of fuel hovering over the engine.
It's certainly do-able, but there are too many variables at this point to nail down a .050" duration, advertised duration, LSA, etc.
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Brent,
First place I was going to start after confirmation from carby builder was to get cylinder heads flowed to confirm flow numbers.
Then see what numbers can be achieved at what $$
Hopefully somewhere close to 300.
What other numbers/ things need to be done before I should consider cam specs?
I have rest of engine/ car built or ready to assemble.
444 cube, 65 galaxie, built c4, 2800 converter, 3.89 diff.
Heavy car, tough street certainly not a daily driver.
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You might experiment with some big-bore single cylinder engine reed valves. I know a few guys who have played with this idea on conventional intake manifolds but not sure if anyone has used them with an IR intake. I know some four stroke MC engines use them.
I would talk to Chris Straub about the cam.
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Brent,
First place I was going to start after confirmation from carby builder was to get cylinder heads flowed to confirm flow numbers.
Then see what numbers can be achieved at what $$
Hopefully somewhere close to 300.
What other numbers/ things need to be done before I should consider cam specs?
I have rest of engine/ car built or ready to assemble.
444 cube, 65 galaxie, built c4, 2800 converter, 3.89 diff.
Heavy car, tough street certainly not a daily driver.
Head flow numbers are very important as well as port volume and valve sizes. You will need to know the exact compression ratio as well. There would also be a difference in cam specs if you go with a plenum type situation, or if you do go with an individual runner setup.
With a 2800 stall, you can't get too carried away with duration. Are you willing to change that, or are you willing to keep the rpms down? If you're willing to keep the rpms down, then I would skip the risk of a solid roller and go for a hydraulic roller. Hydraulic rollers and FE's don't have a good relationship with each other and unless your engine builder or cam grinder has an extensive experience history with that combination, it will be difficult to nail the camshaft down.
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How about my Hillbilly Split Dominators?
Nothing even remotely modern here, an M/T cross ram with 4 Holley 4412 500 cfm 2 barrels. Yes I know they're not Dominators, but at 500 cfm each you can kind'a sort'a think of them that way after a couple beers.
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Cant wait to see the air cleaner, really cool love it 8) ,ha cfm this and cfm that, only numbers thats counts is the one you looking for on bottles and cans ;)with one eye shut,helps focusing :o
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Haha, thats cool!!!
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Measured the carbs.
52mm at the smallest area near the booster.
56mm at the throttle plates.
Independent Runner will be plan A
Plan B might be Jays New Billet runner manifold with a tri power setup or conventional prostock split dominators.
Plan A sounds more interesting but a lot more challenging.
Plan B with TRI POWER be so cool.