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| LTD351 |
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Hello all
Need info on intake plenum and runner design for my turbo engine, I have no idea how to calculate the optimum runner length or plenum size??? Please help me if you can? examples, links, names of experts who might be able to help, anything at all??? I have found some basic info and it says that the runner length has a great effect on where the engine will make max TQ, but less of an effect on HP. Whreas plenum volume effects HP more than TQ??? I am lost?? HELP!!!! |
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I was pretty sure that intake manifold design didn't matter so much when you went turbo. Apart from getting even air to each cylinder. Because the turbo messes up all the resonant tuning of conventional NA cars.
That's why Ford didn't bother installing the BBM valves in the XR6T manifold. Other than that find $40,000 for a 3D fluid dynamics package and an engineering degree. To do it properly there are no simple answers. I worked on a FSAE racing car and you have all sorts of stuff like matching the resonant peaks of the exhaust, intake and working out the velocity of the intake air through the valves and ports at different RPM and the effect of the throttle on air turbulence and restriction.
_________________ Manual EL Gli.
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| EBXR8380 |
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Ammm ??? Id use the F351 lower fab up 8 trumpets on plate , then box over them with alloy box...With two throttle bodies...
Thats for efi... Blow through carb?? I guess big single plain???
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| LTD351 |
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Thanks for the input lads.
EB- I am using clevo heads so normal off the shelf intakes wont fit, only the BOSS manifolds do. So far I have heard that having the plenum volume the same size as the engine capacity is best, but not sure about runner length. I think the runner length I use will be solely dependant upon how much space I have for the runners. |
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general rule is 2.5 times engine capacity for high boost set ups. short runners of the port diam', and trumpets. Have a look at what the hoden guys are doing
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| EBXR8380 |
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Ahhh Clevo!!!Heads....
Check these guys out... http://www.hogansracingmanifolds.com/
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| LTD351 |
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yeah nice pipe work on that car, But I wanna keep mine under the hood.
I think at the end of the day I am only going to be able to build what I can fit under the hood, I'll just go as big as i can with the plenum and possibly try to get a cross-ram style layout with the runners, see if i can find some intake trumpets to suit, have a wide plenum where the trumpets for the right head are on the left, if that makes sense. OR just make something simple and easy, that might actually get finished! probably have more power than I can handle anyway stuff is starting to arrive now, can't wait for the turbo!!!!!!!!!!! |
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Yeah, Id keep it simple to start off with... it'll have heaps of power even befor you start altering the inlet manifold. good luck with it all
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| EBXR8380 |
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Hmmm ??? some ideas..
http://www.hotrodsolutions.net/IntakesEFI.html
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| LTD351 |
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Ran some numbers on an engine analyser program and with the cam i have around 2" runners are most beneficial. Shorter gives more peak, anything more than 2.5" and the whole HP curve drops a bit without much increase in TQ, so 2 it will be. the numbers I got based on head flow, boost and cam specs i have are around the 1000HP and 1000TQ mark, with peak TQ around 4500 (which is where the converter should flash to) and peak power at 6250. The TQ curve is very broad and the HP curve will be very good with the stall I have. I wonder how accurate the program is. Most of the head data was from a buick as there is no clevo heads in the database, and the turbo specs are all a guess as I don't know anything about it but the a/r. So I think the actual results will be different to some degree. When I change the data to that of the CHI 3V's with 218cc runners the power and TQ jumps heaps and boost can be raised some more too.
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Without knowing your turbo specs it wouldnt be too accurate as there is a huge difference in turbos, even those with the same ARs.
I wouldnt get too deep into the numbers just yet, get it all on and sorted and see how it all comes together |
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| EBXR8380 |
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Have you considered using hi flow Windsor heads and boxed TFS R lower manifold or similar ?? It maybe less hassle and could even work out cheaper?? Depending on cost and efficiancy of manifold...
Have you asked Joe or T.M forrums of flow chart for your turbo? That way you'll have some idea of flow numbers.Lb per min of air .etc... Ahh yes you are waiting for the 5 bolt head?? Then the manifold above would fit?
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| LTD351 |
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you are spot on, waiting for the 6bolt heads from World.
Thats why I just got a solid flat tappet, bolt on RR's and use my old heads, also make cheap inlet and use reversed cast iron manifolds just for now, should still make good power just not as much. Once I get the 6 bolt alloy heads, then get custom roller cam, good inlet, make nice thick walled exhaust manifolds, and get some Cu gaskets or cometics, run more boost, I would have done it all at once but the heads arent out yet so... I spent the money i had for the top end on powerglide instead, the clevo stuff only cost about 640$ to fix up heads(hardened seats) and 280$+140$ for custom solid cam, when I get the alloy heads I can put the clevo ones on my everyday car. |
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| EBXR8380 |
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Ummm ??? on 351 your going to have issues anyway with clearance...Maybe converted Boss carb manifold to efi ???
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