Custom Plenum & Cam gear adjustments

[Trust33]

great for a natually aspirated engines plenum, but they only get in the way when used in a turbocharged car.

I tend to dissagree with that

I suppose i think of it like blowing through a straw 1.1@10cm 2.1@20cm 3.1@30 cm long.

The shortest one will allow more flow of air whilst your mouth (plenum) exphells the excess and as the tubes get longer the air passing takes longer to get rid of the air in the plenum.

Given that.the ammout of air that can be consumed by the cylinders and the ammount of gas that the exhaust will pass (thus the need for tunned length extractors) will determine the legnth of the ram tubes.Also the direction of velocity that the air is taking from the intercooler pipe also would play a key role.R&D is a science not a guessing game.

And the engine takes air as it needs it when the plenum has an empty space it fills it with more air it doesnt wait in-line.

I suppose i think of it like blowing through a straw 1.1@10cm 2.1@20cm 3.1@30 cm long.

Id make the front ram a few mm shorter to the last.

[drunkenmaster]

Is there an effective way to measure the air flow to each cylinder?

[S3_Girl]

S3girl's husband: I had a look at it on friday, we were benchracing this plenum last saturday when it was getting fitted. It builds boost quicker with this plenum

but noses over up top. Revs changed aswelll, before it made 270rwkw at around 6800rpm, it now makes 240rwkw up around 7500rpm. It also makes makes slighlty more power on the low boost setting , which from memory right up top bleeds of to the same boost as the high setting(integrale wastegate), but obviuosly loses a tonne of power in the midrange. Physics is a tricky thing :goddam:

cheers

darren

[Trust33]

Yes i suppose you could theoreticly predict the air flow to give a good indication..He hasent given us a plenum volume yet,intercooler pipeing diameter lengths of the ram tubes.

What volume of air can a rb25det induce per cylender?

And i still cant answer your question.

[Sydneykid]

Is there an effective way to measure the air flow to each cylinder?

A/F ratio in each primary pipe of the exhaust manifold.

[dnb]

would you just use a standard a/f sensor ? weld a nut on each pipe and go through 1 by 1 with the sensor and check the a/f ratios?

[Sydneykid]

would you just use a standard a/f sensor ? weld a nut on each pipe and go through 1 by 1 with the sensor and check the a/f ratios?

We have 3 X F&W sensors, so only takes 2 power runs for a complete set of 6 ratios. Gotta make sure they are calibrated the same though.

[dnb]

do you find much variation between cyls? and do you put it down to uneven inlet flow?

[Sydneykid]

do you find much variation between cyls? and do you put it down to uneven inlet flow?

I always flow the injectors, so no variation there. I have found #6 to be the leanest usually, followed by #5. There are a number of possible causes other than inlet distribution differences, but I put it mostly down to that:cheers:

[drunkenmaster]

S3girl's husband:  I had a look at it on friday, we were benchracing this plenum last saturday when it was getting fitted.  It builds boost quicker with this plenum

but noses over up top. Revs changed aswelll, before it made 270rwkw at around 6800rpm, it now makes 240rwkw up around 7500rpm. It also makes makes slighlty more power on the low boost setting , which from memory right up top bleeds of to the same boost as the high setting(integrale wastegate), but obviuosly loses a tonne of power in the midrange. Physics is a tricky thing  :goddam:  

cheers

darren

Doesnt sound the best. be interesting to compare charts?

I have this plenum too as I wanted a front facing T/B for bonnet clearance issues on my RB30DET.

[dnb]

im about to make a custom inlet manifold but i still havent decided if i should make a front feed tapered design or a log style middle feed. any one care to state their theories/experiences?