Ok - so the plenum i've got waiting for my engine 'looks' a bit on the small side...

It'd be a real shame not to use it as its a very well made bit of kit.

Is there a formula i can use to see if its up to the job?

Or are there any 'rules of thumb' i.e

For 'XYZ' power you'll need a plenum of 'ABC' and a minimum throttle body diameter of '123' etc.

Cheers

 

BTTT just for the very clever insomniacs out there

 

Short answer - NO

Throttle body size to some degree is easier to spec. However it is based on two factors, BHP and air density. The greater power you require the larger the TB diameter, but conversely the greater the charge density the smaller the TB you require.

Hence just use a std cossie TB, it will be adequate for whatever you're doing.

 

Cheers Karl,

The Focus WRC Inlet plenum only runs a 56mm body - i was doubtful as to whether that'd support over 350-400bhp and was hoping to push a bit harder than that...

 

how big are the ports in the head? how many cylinders are drawing air at once?

 

GARETH T





I know that it hasn't got any runners on...

It's meant to run with ITBs, but i'll knock up some runners with injector bosses in once i've measured up clearance spaces etc.

The more i look at it - the more it looks 'restrictive'.

The cylinder head is a quite heavily ported ST170 head with +1mm valves. Should have the flowbench figures back midweek...

 

Up for more opinions

 

what car is that off?

 

Its a Cosworth made Focus WRC plenum rear section...

Needs a shit load of work doing to make it useful though

 

it'll be a waste not to run the ITB on that inlet, would look great with them on there but as karl says a standard cosworth throttle will flow more than enough than you will ever need

what i was trying to get at with sizing is,,, that only one cylinder is drawing at any time,,,

 

I know what you're saying mate

But by the same token - i know we've found the limits of evo inlet manifolds and 57mm throttle bodies in the mid 4's - and on GTiR's and the like, we've had to remove the 4 ITB's and chop the end of the plenum off to make a single throttle body conversion.

I want to go single throttle body really for ease - mapping with ITB's on isn't going to be fun, especially as i've got a shot of gas to jet in as well

 

I HATE YOU



+



=

 

how much and how easy are these to get hold of



would you be able to give me some dimensions of this please



might be what im looking for

 

I paid around Ł275 for mine mate - it's a case of keeping an eye on ebay i'm afraid

I dare say phone calls to Ian Howell/M-Sport type people might turn one up for you

Try PMing dub7even on here as well...

The problem is - you only get the rear section - there's 3 sections - the rear, the middle which is the ITBs, water injection etc. - and the front which mates it all up onto the head (which i'm not even sure is the same bolt pattern!)

I'm going to have to do a lot of fab work/drilling/tapping/studding/machining on mine to make it useful - but it is a nice bit of kit and well made

 

yeah mine would be going on a set of jenveys so would need alittle work



but hey ho



i like

 

Yeah - in that case

I'll be speaking to Ian Howell tomorrow - i'll have a word with him - see if he's got any

 

that would be awesome


much apreciated dude