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vwracerdave
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Joined: November 11, 2004
Posts: 15303
Location: Deep in the 405
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 Posted: Mon Jan 13, 2014 8:19 pm Post subject: |
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I agree with what 58 Tub said.
I've said for years the largest engine I would build with dual Kads or ICT's is a 1776. Anything larger is just a waste of money.
A well build 2110 with dual DRLA's or IDF's can get 100,000 miles.
EFI is grossly overated
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clonebug
Samba Member
Joined: January 29, 2005
Posts: 4027
Location: NW Washington
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| Posted: Mon Jan 13, 2014 8:36 pm Post subject: |
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| vwracerdave wrote: |
I agree with what 58 Tub said.
I've said for years the largest engine I would build with dual Kads or ICT's is a 1776. Anything larger is just a waste of money.
A well build 2110 with dual DRLA's or IDF's can get 100,000 miles.
EFI is grossly underrated |
Fixed it for ya Dave..... 
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| vwracerdave wrote: |
Take a good long look in the mirror and report back on what you see. |
| Paul.H wrote: |
| That one line on that chart is probably better info than you can get from this place in a month |
My Megasquirt Fuel Injection Turbo Buggy Build
Water/Alcohol Injection
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Upgraded to MS3Pro-Evo
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http://www.shoptalkforums.com/viewtopic.php?f=3&t=127936 |
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modok
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Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Mon Jan 13, 2014 8:43 pm Post subject: |
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| clonebug wrote: |
And I ask again......Do you think you would have a better chance with a set of worn out rusted 40 year old carbs with the throttle shafts flapping in the breeze that you picked up on the classifieds sight unseen for hella cheap????
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Yeah, actually.
To be specific, the carbs are now more like 20-30 years old.
Guys put them together wrong or whatever and I pick them up for 50-100$ per carburetor.
I prefer junkyard carbs over new. Cheaper and better quality. Same with your ghetto injection |
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bugguy1967
Samba Member
Joined: January 16, 2008
Posts: 4341
Location: Los Angeles, CA 90016
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| Posted: Mon Jan 13, 2014 8:46 pm Post subject: |
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Since no one really answered his question, I'll toss some numbers out there. Feel free to let me know if they're off.
40 IDFs/28 vents - 90-100 HP
44 IDFs/36 vents - 150-160 HP
48 IDFs/40 vents - 190-200 HP
48 IDAs/37 vents - 160-180 HP
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MURZI
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Joined: August 25, 2005
Posts: 5063
Location: Madisonville, La
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| Posted: Mon Jan 13, 2014 8:59 pm Post subject: |
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I think you could add 20-25hp to each of those figures as a max HP
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62 vert
2276
Tim’s welded heads
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modok
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Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Mon Jan 13, 2014 9:03 pm Post subject: |
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| Looks about right, based on venturi sizes of them. |
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MURZI
Samba Member
Joined: August 25, 2005
Posts: 5063
Location: Madisonville, La
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| Posted: Mon Jan 13, 2014 9:09 pm Post subject: |
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Raby routinely pulls 180+ out of 36 vents.
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62 vert
2276
Tim’s welded heads
45 Dells
A1 sidewinder
Fk44 cam |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Mon Jan 13, 2014 9:12 pm Post subject: |
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On this property there are currently two megasquirts and 7 sets of Italian carburetors. It's all good stuff.  |
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58 Plastic Tub
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Joined: September 03, 2007
Posts: 418
Location: Nowhere, USA
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| Posted: Mon Jan 13, 2014 9:18 pm Post subject: |
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Clonebug,
You sir, appear to have woken up on the wrong side of the bed, or had a tough day at the office, or something. You seem to be missing the point of this thread. Whether or not EFI is intrinsically superior, or if I have the native intelligence to tune it (I can assure you, I do) is 100% beside the point.
When you have an hammer, everything looks like a nail. I'm not sure what the deal with Megasquirt crowd on this forum is, but not every discussion needs to devolve into an opportunity to evangelize about EFI.
The point of this thread was not to compare IDAs to EFI. The point was to establish a maximum displacement and horsepower for one specific, size tiny carburetor kit (Weber ICTs)-- not for you, or me, or anybody but this one particular guy... who happens to believe that any stroke over 69mm is "askin' fer trouble" anyhow.
FWIW, you don't have to convince me of the near limitless possibility of digitally controlled spark and fuel metering. I'm on board, especially as it relates to spark. As an aside to my aside-- it'd also be really neat to have variable valve-timing and more controlled coolant temperatures, but then we'd have a Subaru. That's not bad, but it's beside the point.
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"Everybody is entitled to their own opinions, but not their own facts." |
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johnwesley
Samba Member
Joined: May 08, 2013
Posts: 165
Location: Mena, Ar
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| Posted: Tue Jan 14, 2014 6:54 am Post subject: |
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| bugguy1967 wrote: |
Since no one really answered his question, I'll toss some numbers out there. Feel free to let me know if they're off.
40 IDFs/28 vents - 90-100 HP
44 IDFs/36 vents - 150-160 HP
48 IDFs/40 vents - 190-200 HP
48 IDAs/37 vents - 160-180 HP |
so a persion looking to get 130-140 hp is better off with 44idf? what about rpm that the engine is spinning? doesn't that make some diff on carb size?
does a 2.3l turning 5000rpm and making 140 need the same carb as a 1776 making 140 at 8000 rpm?
just curious 
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ralf
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Joined: July 08, 2008
Posts: 1215
Location: r4
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| Posted: Tue Jan 14, 2014 7:32 am Post subject: |
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it would need more carb...
although doing the numbers and math it lets us see it should be "close"
but in reality it isnt the case...
just like it is possible to run a 1600cc type1 to make 170whp with 48ida's and 9000rpm
not everyone could make a 2276 with 40idf's do 170whp
it also prolly would depend on the application.. i think the 2276 could hit the mark with 40idf;s and peak at 4k rpm be done by 5pm LOL
then u have to factor in valve size...
could proly have a 44idf on a 1776 and its good enough..
spin it higher and run 44 valves = gonna be weird having the same valve and throttle plate... how do u ratio the vents
but there are better experts that would chime in.. let us wait
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ALB
Samba Member
Joined: August 05, 2008
Posts: 3483
Location: beautiful suburban Wet Coast of Canada
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| Posted: Tue Jan 14, 2014 2:57 pm Post subject: |
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Guys- I've asked and posts have been removed that weren't pertinent to the discussion; yes, I know fuel injection is superior and has all sorts of wonderful benefits but this is about what about carbs can do. If some of you want to discuss carbs vs fi further, start another thread. As I've said before (2 or 3 times now), the gentleman has a set of carbs and is intent on using them, and we have to respect his wishes. As Stan (58 Plastic Tub) pointed out, we're just trying to get him comfortable with going a little bigger.
I appreciate the info given and if anyone can expand on any of the questions in my original post that would be great. A couple off the top of my head- Gerico got 158hp (6,000rpm) with 40IDF's on his 2276; is that their limit, or has anyone gone higher? What's the limit of 44's (IDF's) or 45Del's with 38mm vents? Anybody machined 39mm vents? How'd it run? Again, thanks for your time. Al
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AlteWagen
Troll
Joined: February 23, 2007
Posts: 8501
Location: PNW
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| Posted: Tue Jan 14, 2014 5:05 pm Post subject: |
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Ive used ICTs on several engines over the years, 1500, 1600, and a mild 1914. Off idle torque was great but mid and top end suffered and was done by 4500 rpm. If there is no choice but these carbs dont bother getting a cam bigger than W100 or Web 218
I know a few people that have ended up putting some on a Type 4 2L/1800 and while better than the progressive/FI. In the end both engines suffered seat failure attributed to extremely worn throttle shafts causing equally extreme lean conditions which are NOT good for a bus with a load.
Dual singles are good starter carbs for a beginner not concerned with high performance. Dual dbl barrel carbs will get the most of any size engine and if quality linkage and air filtration is used the throttle response and power output cant be beat.
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modok
Samba Member
Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Tue Jan 14, 2014 5:58 pm Post subject: |
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| ALB wrote: |
A couple off the top of my head- Gerico got 158hp (6,000rpm) with 40IDF's on his 2276; is that their limit, or has anyone gone higher? What's the limit of 44's (IDF's) or 45Del's with 38mm vents? Anybody machined 39mm vents? How'd it run? Again, thanks for your time. Al |
I don't know how some of the DRD dyno results are so high. Not the only one.
Based of WAG and bugguy's estimates, I made up a rule of thumb:
HP potential is venturi size squared, divided by eight.
And, like I mentioned, venturi should be 75%-86% of carb bore.
We could create a more scientific formula.........but honestly I think that's more than close enough for benchracing. Of course all rules of thumb can be bent if desired, but I don't know why you'd want to, unless it's in the rules.
What happens if the venturi is too big for the carb?? Usually can be made to run ok at WOT, and IDLE, but in between......is weird |
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58 Plastic Tub
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Joined: September 03, 2007
Posts: 418
Location: Nowhere, USA
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| Posted: Tue Jan 14, 2014 6:52 pm Post subject: |
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| modok wrote: |
[Based of WAG and bugguy's estimates, I made up a rule of thumb:
HP potential is venturi size squared, divided by eight.
And, like I mentioned, venturi should be 75%-86% of carb bore. |
So, I ran some numbers... and it's like magic! 38 vents= 180 hp. 40 vents- 200 hp
... 26 vents? 85 whoppin' hp. Yep- 1835, thick-wall 92s, and a W100 cam. He'll love it. Maybe we think he shouldn't, but he will.... 
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bugguy1967
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Joined: January 16, 2008
Posts: 4341
Location: Los Angeles, CA 90016
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| Posted: Tue Jan 14, 2014 7:24 pm Post subject: |
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So I was pretty close! That was all just from reading old HVWs back issues from the 80s till now!
Gerico's 160 HP was with what vents? 40s have vents available up to 34 or 36.
I must add that I'm positive that only a very small % of people know how to build a combo that will get max carb and head flow at powerband peak, so my numbers were cushy.
Jake Raby's got computers, flow benches and dynos to get the most outta them.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine" |
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johnwesley
Samba Member
Joined: May 08, 2013
Posts: 165
Location: Mena, Ar
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| Posted: Tue Jan 14, 2014 7:43 pm Post subject: |
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| modok wrote: |
I don't know how some of the DRD dyno results are so high. Not the only one.
Based of WAG and bugguy's estimates, I made up a rule of thumb:
HP potential is venturi size squared, divided by eight.
And, like I mentioned, venturi should be 75%-86% of carb bore.
We could create a more scientific formula.........but honestly I think that's more than close enough for benchracing. Of course all rules of thumb can be bent if desired, but I don't know why you'd want to, unless it's in the rules.
What happens if the venturi is too big for the carb?? Usually can be made to run ok at WOT, and IDLE, but in between......is weird |
If you run the numbers and it looks like a 32 venturi is the size needed what ratio would you then use for the valve size? I assume you would want a 40x35 head with that size vent.
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modok
Samba Member
Joined: October 30, 2009
Posts: 26785
Location: Colorado Springs
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| Posted: Tue Jan 14, 2014 8:12 pm Post subject: |
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Yep, that would be about right.
Could use 40idf w32, or better yet 44 idf with33, or even better 40 dellorto DRLA with 32, or one of the other more exotic italian models |
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AlteWagen
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Joined: February 23, 2007
Posts: 8501
Location: PNW
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FV195
Samba Member
Joined: February 19, 2005
Posts: 480
Location: carlisile, pa
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| Posted: Tue Jan 14, 2014 8:34 pm Post subject: |
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| I am running dual 34 webers with a 110 cam in an 1835. 042 heads, it pulls strong to 6k. Lopey idle good drivability got such a deal on the carbs, planned to upgrade later, but very happy with them! If I was going to change I would go with a single double barrel to make working on it easer, engine removial and plug changes, it's in a 74 thing if that matters to anyone |
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