7/14/2023 0 Comments Turbo calculator hp![]() Right so have found a calculator for accurately calculating the runner lengths from valve to the plenum to be on target to the 2nd or 3rd harmonic to of what i wanted.Īs for the plenum size and design general rule of thumb I formed was that a plenum volume be of approximately double the engine capacity is a good place to be and if end fed from a throttle body to have a ruff taper across the plenum to maintain the air speed towards the furthest cylinder away from the throttle body and to have them all be feed equal, plus have all the runners be trumpet shaped of the plenum into the runners to the Chambers.(So just like a set of individual intake trumpets but inside the plenums base plate) So would this be to take again a ruff ball educated guess to what it's going to make, set it up, Map it see what your get power wise then correct from there to refine? Was hoping for a more mathematical calculation to figure single TB from the start rather than this of needing to wastefully be making inlets, getting TB's to test and home it in that way □Īlso the new question possed here is to how to calculate plenum size if focusing on just upto the TB.? 63mm working for 200bhp engine 7500rpm peak.) Even thou 63mm gives 223bhp on the graph they say to go 10% bigger than to that what the engines making to play safe to no restriction. 45mm as above) but for single TB I see alot based on throttle body size figured off rpm and power output so (e.g. (Itb's is case of just match the runner diameter you have calculated e.g. Still as say how do you then calculate throttle body diameter accurately for single tb turbo. So only way i can see to figure accurate runner diameter would have to make a ruff ball guess on diameter then map the car see what your getting max VE in boost then adjust diameter of the pipe proply based on that to then make the calculation work for you and be more accurate.Īm taking that again the plenum is going to work as a dampner so be making the runner length calculation work from plenum to back of valve match harmonic. Two questions thou So in running a plemun and single tb setup the runner diameter would be figured like ITB's would "but" the calculation above then wouldn't work straight off for that of your peak VE would be higher in boost depending on amount of boost etc etc. ![]() And yes the idea of using just upto the TB makes sense being as you say the intercooler would act as a dampier to the harmonic infact so would a plenum so just upto there. OK so I get what your saying when it comes to pressure not changing the harmonic bit like blowing on a trumpet harder your blow still gets the same note. Heck, maybe incorporate into the vehicle with a suitable controller.įor the TB diameter, as has been said, around 45mm shouldn't restrict it and still allow a degree of throttle control at small openings - some sort of progressive linkage should help a lot there. ![]() If it's something you are really interesed in following up, you could fabricate a manifold with two main parts - the planum and slip tubes, and the head flange with matching tubes that allow the two to slide like a trombone. ![]() In this application, I wouldn't concerm myself with anything up-stream of the TB, as what pressure waves aren't dampened, absorbed and dissipated within the plenum shouldn't be able to make much affect as upstream there is considerably larger volumes of air, flexible hoses and fittings, and a charge cooler that will act like a massive pressure dampener. ![]() The runner diameters should be the same, as it's moving the same volume of air, or so I would expect. I looked for a few minutes and there doesn't seem to be easily found data on the affect of pressure, but i seem to recall an engineer saying the difference was negligible, but may be mis-remembering it. In theory, you should be able to use one of (or several and take the mean value(s)) the available formulae for the overall runner length, as you would for N/A, and modify it for the change of the pressure wave velocity under the higher pressure. Just to confirm, this is a single throttle body on a plenum that feeds individual runners to the cylinders? My thoughts as discussion points - don't take them as gospel. ![]()
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