Build your own twin plenum
Discussion
Anyone ever seen this done before ?
Not sure how he's handled the airflow metering but seems feasible otherwise.
http://www.mgbv8.co.uk/twinplenum.htm
Chris
Not sure how he's handled the airflow metering but seems feasible otherwise.
http://www.mgbv8.co.uk/twinplenum.htm
Chris
i've yet to see any reliabe data for these types of plenums, but seing as thetd single plenum is rstrictive, and even a 72mm plenum starts to lose flow over a massive opening at 270hp worth of airflow I cant see any good reason why these siamesed plenums shouldn't work at least in pure airflow terms.
Nick spent a huge amount of time on that plenum but the car's not quite finished so we don't know if his work was worth the effort. I once did something similar but with a pair of chargecoolers inside which could be removed/changed if need be. My plenum ended up looking square and had a central pivot on top to work the throttles. The coolers could be pulled out from the front.
Boosted.
Boosted.
How would you handle the airflow meter?
Does the airflow meter just output a voltage in proportion the the airflow ?
If so it wouldn't be that hard to build an electronic circuit to 'add' the voltages together, assuming the ECU could still handle the higher voltage ranges.
Or would you just go for an ECU that didn't need any metering ?
Doing that though I guess you'd never know just what advantage you get with the twin plenum over the standard one.
The Rover twin plenum always seems restrictive to me with a single airflow meter.
Does the airflow meter just output a voltage in proportion the the airflow ?
If so it wouldn't be that hard to build an electronic circuit to 'add' the voltages together, assuming the ECU could still handle the higher voltage ranges.
Or would you just go for an ECU that didn't need any metering ?
Doing that though I guess you'd never know just what advantage you get with the twin plenum over the standard one.
The Rover twin plenum always seems restrictive to me with a single airflow meter.
Interestingly enough my first job was at TWR with a chap who had one of the old SD1 touring car lumps in his TR7, he said during the sd1 touring car development they tried making a plenum just like this one and it was worse than standard.
Only when they moved the intakes side by side to produce the twin plenum design did it outperform the std intake.
The reasoning at the time was the incoming air-streams collide with each other and created a partial vacuum inside the plenum.
I suppose you could potentially sort it by having a wall between the two halves.
Matt
Only when they moved the intakes side by side to produce the twin plenum design did it outperform the std intake.
The reasoning at the time was the incoming air-streams collide with each other and created a partial vacuum inside the plenum.
I suppose you could potentially sort it by having a wall between the two halves.
Matt
350Matt said:
Interestingly enough my first job was at TWR with a chap who had one of the old SD1 touring car lumps in his TR7, he said during the sd1 touring car development they tried making a plenum just like this one and it was worse than standard.
Only when they moved the intakes side by side to produce the twin plenum design did it outperform the std intake.
The reasoning at the time was the incoming air-streams collide with each other and created a partial vacuum inside the plenum.
I suppose you could potentially sort it by having a wall between the two halves.
Matt
I can verify this as well, i have dynoed a few motors with this set up one being a 4.2 a 5.0 and a 5.2 for different customers the end results have all been the same, absolute outright bhp so above 5500 rpm it picks up a little, on the 5.0 ltr it gained 5bhp, however on all 3 engines they lost bucket loads low down and mid range, the said 5.0 lost 35 ftlb at 2500 rpm, over a 72 mm plenum. Only when they moved the intakes side by side to produce the twin plenum design did it outperform the std intake.
The reasoning at the time was the incoming air-streams collide with each other and created a partial vacuum inside the plenum.
I suppose you could potentially sort it by having a wall between the two halves.
Matt
Barkychoc said:
How would you handle the airflow meter?
2 ways: Ditch it in favour of an aftermarket ECU
Make something like "MafSim". It simulates MAF sensor voltages given throttle, manifold pressure and temperature inputs - none of which are affected by having multiple throttles.
http://www.teamcarr.pwp.blueyonder.co.uk/MAFSIM/
I suspect that if you have the time and skills to do the 2nd, a VEMS or Megasquirt would be well within your capabilities and the better choice of the 2.
BTW, I have a true twin plenum on my Griff now - The first of it's kind. 2 throttle bodies and 2 totally separate plenums, each feeding half the cylinders such that alternate cylinders are fed from alternate plenums. Oh and long primary tubes too.
It's just a shame it doesn't run yet due to a broken throttle cable, lack of air filters and a lack of time to fix it...
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