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  #16 (permalink)  
Old 01-05-2012, 05:28 AM
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Quote:
Originally Posted by KA67_72
With your converter you may not have issues with tip in. Even if you have problems with it at first, there are things you can do to sort it out like progressive linkages.

Kevin

What things can one do about tip in, it sounds like you have some info perhaps?

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  #17 (permalink)  
Old 01-05-2012, 06:22 AM
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Quote:
Originally Posted by Project89
how about a common plenum per 2 cyls, sinc eno 2 cyls on the same side will be pulling air at the same time if u built a common plenum feeding 2 runners using 2 tbs to feed each plenum, should solve the issue of them being to small.

though this woudlnt be a true itb setup, i would assume it would still act the same as if it were
perhaps the worst intake design ever. I'm not going to get into why but you need to balance the pulses.

As for tip in slide carbs, efi throttle bodies, or carbs wil accelerator pumps will fix that.

Compared to a tpi unit the total throttle plate area is bigger but each runner doesn't pull from the total area.

A rule of thumb is that the throttle bore should be about the size of an intake valve on a good ir setup (assuming a hot well sorted out engine build). That puts you at no less than a 50mm throttle bore. Depending on the carb design going to a 52 or 54 may be needed.
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Old 01-05-2012, 06:43 AM
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Don't worry about tip in now. Get it running. If it's an issue you can deal with it later.

Kevin
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  #19 (permalink)  
Old 01-05-2012, 09:11 AM
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I think i am going to run a carb while i build this setup - this is fairly complicated. I am planning on running efi with itbs not carbing it. a carb setup sounds like a pita to tune and keep running with out adjusting it every time i take it out of the garage.

I was thinking a max of 50 with what I am doing. I am not sure if there is a motorbike with that large of throttle bodies with efi.
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Old 01-05-2012, 05:04 PM
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Originally Posted by ap72
perhaps the worst intake design ever. I'm not going to get into why but you need to balance the pulses.
please do im here to learn just like most are.over the years i have designed and built many one off custom inatkes for my own v6 turbo camaro.
some have worked very well with hp gains of almost 40hp over a ported stock intake. and some while making big numbers had lots of issues at cruise.
i did all of these by trial and error along with a few others that i can post actual pics of once i rember my photobucket password lo.

so id love to learn more for future intake builds





another




and one other itb design i never did finish

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Old 01-06-2012, 06:35 AM
How fast is fast enough?
 
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While I'm sure you enjoy making intake manifolds, your approach is all wrong. You need to tune the intake dimensions based off of total runner length, csa, and taper. They also need to transition from the plenum and head in a manner that is as least disruptive as possible. I'm not going to get into it here but Google is your friend. If you spend more time with a calculator and paper before you bust out the welder you'll have MUCH better results. Intake manifold tuning is even more complex than exhaust tuning.
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Old 01-06-2012, 12:27 PM
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Quote:
Originally Posted by ap72
While I'm sure you enjoy making intake manifolds, your approach is all wrong. You need to tune the intake dimensions based off of total runner length, csa, and taper. They also need to transition from the plenum and head in a manner that is as least disruptive as possible. I'm not going to get into it here but Google is your friend. If you spend more time with a calculator and paper before you bust out the welder you'll have MUCH better results. Intake manifold tuning is even more complex than exhaust tuning.
funny you say with a calculator, that is literally how i think. i plan then do. in other words i 100% agree with ap72 here.
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  #23 (permalink)  
Old 01-06-2012, 03:27 PM
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Quote:
Originally Posted by ap72
While I'm sure you enjoy making intake manifolds, your approach is all wrong. You need to tune the intake dimensions based off of total runner length, csa, and taper. They also need to transition from the plenum and head in a manner that is as least disruptive as possible. I'm not going to get into it here but Google is your friend. If you spend more time with a calculator and paper before you bust out the welder you'll have MUCH better results. Intake manifold tuning is even more complex than exhaust tuning.

those were rough drawings just to get my ideas into a visual state, the actualy manifolds were all bellmouthed were runners met the plenum, tapered runners etc also not shown is the base, they were all 2 part manilfolds. at the time when i drew those up i didnt know how to draw in bellmouths and how to draw complicated bevels so i did them as simple as possible.

i actually need to remember my photobucket password so i can get picks of some of the finished manifolds i built

the top manifold was also adjustable the plenum and base bolterd together over the runners i had 3 diff lenght runners that could be swaped out

and i also wouldnt call a 40hp gain a wrong aproch

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Old 01-13-2012, 01:33 PM
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So - anyhow, any opinions on mm size for the throttle bodies for a 180cc port size on the heads?
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Old 01-13-2012, 02:27 PM
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Many, many years ago, Ed Iskenderian used to recommend, I think, 1 square inch of venturi for each 40 hp. A venturi diameter of 1.13" will yield a venturi area of 1.002 square inches. I'm thinkin' that 1.125" would work (0.994 square inches) and might be easier to machine to. We're talking venturi size here, not throttle bore size.
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Old 01-14-2012, 12:52 AM
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ITBs would look cool. How about a stand alone EFI "carb style" like the FAST EZ EFI or Powerjection III. You could run a carb now and then upgrade later with out switching manifolds or complicated fuel mapping. Where does the MAF sensor go with the ITB set up you are looking at? Is there one per cylinder or do you need a common plenum feeding the ITBs?


Also you mentioned plumbing in dry nitrous. Just an FYI, you can't get on a road race course with a bottle in the car. Even if it's empty and disconnected.
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Old 01-14-2012, 08:56 AM
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With 180cc runners I assume you're running a 1.94" valve and targeting around 400hp. With those guidelines a 50mm throttle body is about right, going smaller will help throttle response going larger will slightly help top end hp. If its a road course car I would go on the slightly smaller side to help throttle response, maybe 48mm. Don't forget to tune your length and taper as well.
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  #28 (permalink)  
Old 01-15-2012, 10:13 PM
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Quote:
Originally Posted by ap72
With 180cc runners I assume you're running a 1.94" valve and targeting around 400hp. With those guidelines a 50mm throttle body is about right, going smaller will help throttle response going larger will slightly help top end hp. If its a road course car I would go on the slightly smaller side to help throttle response, maybe 48mm. Don't forget to tune your length and taper as well.
180mm with 2.02/1.60 valve

I was also told that the cfm at max lift the heads will allow is also a factor. I agree that on the smaller end but not too small would be best as well. I am not sure hp goals can be considered in this. Instead- what the engine configuration is. ie the size valve as aforementioned and intake runner and compression and bore/stroke and cfm at allowable lift through the heads etc.
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Old 01-15-2012, 10:15 PM
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Quote:
Originally Posted by Landshark928
ITBs would look cool. How about a stand alone EFI "carb style" like the FAST EZ EFI or Powerjection III. You could run a carb now and then upgrade later with out switching manifolds or complicated fuel mapping. Where does the MAF sensor go with the ITB set up you are looking at? Is there one per cylinder or do you need a common plenum feeding the ITBs?


Also you mentioned plumbing in dry nitrous. Just an FYI, you can't get on a road race course with a bottle in the car. Even if it's empty and disconnected.
Noted on the bottle, the map would be in the actual intake (that cross the heads and valley) past the itbs.
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  #30 (permalink)  
Old 01-16-2012, 07:17 AM
How fast is fast enough?
 
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Your map cannot just go to the intake. What heads are you looking at? What are your goals? Your goals should be the first thing you're considering.
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