Big Intake

Just had the extrusion delivered from the US so I can now make a start on the plenum chamber for my n/a, I cut a small test piece and had a practice to see how it will come out complete with velocity stacks, every thing will be bolt on no welding.. I want to do it this way as I will be using the standard throttle body to start with then a q45 thereafter so all I will need to do is machine a new end plate and bolt it up

This is what I am trying to achieve

Looks great...How much do you think it will owe you?... good luck with it:)

Looks great...How much do you think it will owe you?... good luck with it:)

The expesive part is the D extrusion that has cost £90 delivered from the US other bits few quid, machining is what I do for a living so nothing to do it all.

will you still be able to keep the battery in situ?

You won't have to cut the plenum back by the #6 intake runner as you're not LHD like the one in the pic????

Doing this like in the pic will hurt distribution to that cylinder. Really you want it to be sloped the other way so there's more volume for the #6 runner to draw on.

Battery will go into the boot and will need to relocate the PS resevoir, I weighed that up about cutting the back at 45deg and realised I dont need to do it, I was thinking of splitting the chamber in two for better distribution to the back cylinders but dont think I will gain anything for the extra work, we'll see how it goes I might monitor both 1 & 6 for egt's after

Nick do you not think the plenum should taper a little?

Sorry my bad just saw the last picture

that looks sweet, any chance of you knocking these up in your spare time

More pics of my progress, just the stacks to machine now and vacuum holes

nice one, very well done

Brilliant work mate

The expesive part is the D extrusion that has cost £90 delivered from the US other bits few quid, machining is what I do for a living so nothing to do it all.

Fancy knocking a few more out after you have finished for a tidy profit trader membership

It looks very nice, but you also have to take into account airflow inside, when it is under pressure.

If it was flowing water, it would probably be OK, but air has some nasty habits of creating high-and low pressure regions so that under stress some cylinders will see fewer air molecules than others. And it's not always the 'obvious' ones either.

Ideally you need to do some R&D, fitting bleeding nipples on the runners (that you can later cap off) and verifying that under vacuum or boost there is no pressure difference among any two cylinders. If there is (most likely case) then you have to start tapering the inside until they are all equalised.

It's not trivial either - 10% more air in cylinder 6 compared to cyl 1 means that cyl6 will be running leaner than 13:1 when cyl1 is at 12:1 (assuming the ECU is allowing the same amount of fuel in all cylinders)

Performance-wise, it is very important for all cylinders to be making the same power at the crank, so they are not working against each other.

Safety-wise, remember that your wideband will be showing an *average* of the 6 AFRs of all cylinders, so you can potentially get a holed piston without the WB showing anything nasty.

Why can't anything be simple

It looks very nice, but you also have to take into account airflow inside, when it is under pressure.

 

If it was flowing water, it would probably be OK, but air has some nasty habits of creating high-and low pressure regions so that under stress some cylinders will see fewer air molecules than others. And it's not always the 'obvious' ones either.

 

Ideally you need to do some R&D, fitting bleeding nipples on the runners (that you can later cap off) and verifying that under vacuum or boost there is no pressure difference among any two cylinders. If there is (most likely case) then you have to start tapering the inside until they are all equalised.

It's not trivial either - 10% more air in cylinder 6 compared to cyl 1 means that cyl6 will be running leaner than 13:1 when cyl1 is at 12:1 (assuming the ECU is allowing the same amount of fuel in all cylinders)

 

Performance-wise, it is very important for all cylinders to be making the same power at the crank, so they are not working against each other.

Safety-wise, remember that your wideband will be showing an *average* of the 6 AFRs of all cylinders, so you can potentially get a holed piston without the WB showing anything nasty.

Totally understand what you are saying and it would be easy to tap each runner and attach pressure gauges to measure presure in each of them and applying a airline with a gauge through a sealed end, not sure about vacuum though but would that matter too much as it is lean anyway when it is sucking air and not under positive pressure?, here is a pic of a plenums inside that jamiep has just got (post *48) http://www.mkivsupra.net/vbb/showthread.php?t=86368&page=4

...it would be easy to tap each runner and attach pressure gauges to measure presure in each of them and applying a airline with a gauge through a sealed end, ...

No pressure line, that is a static condition and everything will look honky-dory. You need to check the readings while there is realistic airflow through the intake, and the engine is consuming air.

Therefore you need to look for pressure differences with the engine running and boosting

If you can't get your hands on differential gauges, then 6 cheap identical boost/vaccum gauges are the next best thing.

They could be fixed next to each other on a piece of plywood, and the passenger could have them in his (or her!) lap while you're boosting. It would immediately be clear if one is lagging behind.

duplicate

Looks a nice bit of kit mate well done

Looks like some tidy machining!

Best of luck!

got onto this one a bit late, how is it going ? is it on the car yet ?

That's a work of art that is!

I'm very jealous of your skills.

How did it work out in the end?

Hi Bromy, did you finished it yet?