72mm plenum vs act twin carbon plenum .
Discussion
SILICONEKID 345HP 12.03 said:
trev4 said:
There is another option, Mat Smith has modified a standard plenum to take a 90mm throttle body, I am toying with having one fitting to mine when he fits the Emerald system after Christmas.
Phazed tried that and the result was less power .That was on my 4.6. What you ddin't know is that we found during a leakdown test after was that I had a lot of valve leakage going on.
I had the heads refurbed but went back to a single plenum without refitting the bigger throttle bodied plenum............ anything is possible.
As for increased performance with a twin? You have great results with your single do I doubt that there is much more to be had but as said, throttle response should be better.
My 5.5 has a triple and response is instant, you have been in my car on track if you remember.
https://m.youtube.com/watch?v=fa5oKqEgkME
You just got to make sure the overall diameter will not be too large for your flow (in laymen's terms) - or as I understand it gas speeds will drop with undesirable consequences on VE and therefore torque and consequently power. And obviously not too narrow.
So you need to calculate what the optimum diameter will be for your capacity/revs and make a decision from there regarding the specifics of the various options on offer, I would have thought...
Edited to add: I assume the maximum flow characteristics of the intake manifold will have a bearing on it too, as they appear to be the main restriction once you have nicely ported heads as you do.
So you need to calculate what the optimum diameter will be for your capacity/revs and make a decision from there regarding the specifics of the various options on offer, I would have thought...
Edited to add: I assume the maximum flow characteristics of the intake manifold will have a bearing on it too, as they appear to be the main restriction once you have nicely ported heads as you do.
Edited by Dominic TVRetto on Sunday 24th December 22:38
Having read about Plenum capacities in the distant past isn’t the size of the Plenum itself an issue on highly tuned engines as it’s already marginal how much air it can process on a 5.0
The capacity of the Plenum rather than how much air can hit it sort of thing.
So unless your Plenum is slightly bigger your overall performance won’t change much.
Are the Act ones bigger in capacity to standard.
This is assuming nothing else is holding the induction back.
Then there’s exhaust gases that from recent reading is also holding these engines back.
I recently drove Peters car trying to keep up with him in mine and I noticed the instant go.
Thought it was just his engine and torque but I do think the throttle bodies gave high speed air flow into the Plenum and a sense of instant power.
Possibly negates the loss of torque you’d get without it on his high sucking engine.
As said above you’d ideally need to make some calculations as to how much air the intake pipe can draw before going any further!
The capacity of the Plenum rather than how much air can hit it sort of thing.
So unless your Plenum is slightly bigger your overall performance won’t change much.
Are the Act ones bigger in capacity to standard.
This is assuming nothing else is holding the induction back.
Then there’s exhaust gases that from recent reading is also holding these engines back.
I recently drove Peters car trying to keep up with him in mine and I noticed the instant go.
Thought it was just his engine and torque but I do think the throttle bodies gave high speed air flow into the Plenum and a sense of instant power.
Possibly negates the loss of torque you’d get without it on his high sucking engine.
As said above you’d ideally need to make some calculations as to how much air the intake pipe can draw before going any further!
Bigger plenum doesn't work as the extra air available is the wrong side of the throttle and can cock up the already poor response. I experimented for a while with the 'spacers' and concluded they are fit for the bin and nothing else. You want the extra air into the engine and not filling a bigger void first. As someone has already commented other factors come into play with the air flow and speed and just chucking stuff on here and there can make things worse.
Happy Christmas guys
Happy Christmas guys
Edited by macdeb on Monday 25th December 14:10
Edited by macdeb on Monday 25th December 14:12
So looking at the science of it
There’s no ram air effect as the filter or in Daz case filters are side onto the rushing air.
So your relying on compression and sucking the air in via your pistons.
Would a bigger air intake pipe be the first thing to change or is it accepted the standard one 65mm or whatever it is will supply enough air on a high hp engine.
Intakes simple to me, pucker up your lips and suck with a small hole, high resistance, open your chops wide and suck,,,, simples lots of air.
Air speed is very important as slowing down the air can have detrimental effects on fuel air mix so it’s not just as simple as just supplying lots of air.
I’d have thought the inlet manifold is the biggest restriction as is the valve/ Cam set up.
Bigger hp means an even higher lift cam surely.
Chilli car with a big handmade air box before the throttle bodies has big hp so maybe there’s something in it.
There’s no ram air effect as the filter or in Daz case filters are side onto the rushing air.
So your relying on compression and sucking the air in via your pistons.
Would a bigger air intake pipe be the first thing to change or is it accepted the standard one 65mm or whatever it is will supply enough air on a high hp engine.
Intakes simple to me, pucker up your lips and suck with a small hole, high resistance, open your chops wide and suck,,,, simples lots of air.
Air speed is very important as slowing down the air can have detrimental effects on fuel air mix so it’s not just as simple as just supplying lots of air.
I’d have thought the inlet manifold is the biggest restriction as is the valve/ Cam set up.
Bigger hp means an even higher lift cam surely.
Chilli car with a big handmade air box before the throttle bodies has big hp so maybe there’s something in it.
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