I've mentioned before that i'm working on some 5PW R1 throttle bodies for my track car and just wanted to see if my calculations for the runner length is about right and i'm not making some hideous mistake.

Does a runner length of 303.125mm sound reasonable if i'm aiming for peak torque at 5,500rpm?
I believe that the calculation i used aims to use the second wave reflection which i read is the most effective for improved induction.
I have used 205* as the cam duration which i believe is the standard XU10J4RS duration, although i'm undecided whether to get some slightly more agressive cams.


Another question is about the ram pipes, from research it appears that the ideal angle is somewhere between 7* and 7.5* from the axis, and that a big radius is better, and that the radius is to stop after 90* from the axis to prevent air being sucked in from behind the ram pipe opening. Is there any ideal radius or is it a case of the bigger the better?


The final question i have at the moment is about the air filter, i've read all over the internet how awful socks are so i'm undecided whether to go down the route like yanni took with an airbox with a paper filter element in and run this to the front grille to get maximum cold air, or whether to use a foam style filter like the itg jc50.


Thanks in advance for any help/advice.

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Goldie the track car.

Thanks for the feedback, I saw those adjustable ram pipes in a magazine a while ago.
From more reading it seems there is no set length and calculations are only for a rough idea, so i may have to knock up something similar to them to allow for quick and easy adjustment during mapping.

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Goldie the track car.

inlet length is very important, key to mid range torque. look at a pug1off dyno graph and all there torque figures seem abit low, even on there 300hp n/a race builds peak torque is only around 180lb. with a decent inlet tract should be able to see those kind of torque figures from around 220 bhp... (ie my brothers engine 194bhp@wheels, 179 ft lb )
this is partly due to running a short inlet manifold, jenvey/longman usually. ive always believed a stronger mid range is better than a peakier engine due to having the grunt where you need it when exiting a corner. Where do you want power? not at 8.5-9k imo.


ive just been out and measured my length......

inlet is 145mm from head to the join of inlet/tb's

jenveys are 115mm

trumpets are 40mm

overall length 300mm


in my honest opinion, don't waste the time messing around with bike bodies. no home grown bike bodie setups are ever that good, there pretty good at not the producing power and inlet leaks with bodged manifolds though... costing time and money on the rollers.
the only good bike bodie setups are the TU ones that colin satchell makes, proper inlet, proper trumpets and properly designed and proven.

go down the Jenvey route or speak to colin satchell about the 45mm lotus tb's, one of his decent length inlets and some trumpets.

re filter, please don't buy socks whatever you do, the trumpets rub on the filter and parts of foam get sucked in to the engine, ive seen first hand throttle jamming open. also getting sucked in and sticking to the spark plug making it run like a back of shit. buy a proper itg filter or somthing similar

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230 hp 2.1 16v XU 205 rallye on jenveys Project thread here
309 3dr K20 Type R

good luck with it sounds like your going to be doing it properly

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230 hp 2.1 16v XU 205 rallye on jenveys Project thread here
309 3dr K20 Type R

Whats wrong with bike bodies? I got one 306 s16 with 42mm bike bodies and cams and one std. s16.
with the funny inlet manifold. The one with bike bodies outperform the std. one from any rpm ,speed and gear.And that without a remap.

I think buying Jenveys is a waste of money,when you can buy cheep bike bodies.
Its all about how you fit them.

Remember somebody cant hammer a nail thru a pice of shit without destroying both.

Oh yes it overflows. I dont wanna hurt somebodys feeling but there is so many bad "mecanics" out there.
Last night i talk to a man that runs a 405mi16 in something we call rallycross here in Norway.He had bought a chip that would give the mi16 50hp extra without any other work.
I think he is lucky if he find 1hp with that chip.

I like the word too.

I've had a little more time to play about in CAD tonight, i only did the throttle bodies as simple blocks as it would be far too time consuming to model them properly, however they are dimensionally correct for the bits that matter.
Here is my intended setup so far:


I havent bothered with trumpets yet, still undecided on how to mount them to the bodies.

Here's a slightly better view of the inlet side of things.



Jim, do you think it would be difficult to weld the normal inlet manifold casting to the flange? I think the flange material will most likely be HE30 grade. (I'm not a welder and not too in-the-know with welding alloys).
The flange will have pockets milled into the rear face for the runners to sit in, the runner ends will be milled flat so they sit inside the pockets nicely.

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Goldie the track car.

Lego bodies FTW

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Team 'unintentional rat look'

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