Air Requirements??
Discussion
Probably a simple question, but I'm sure the answer takes some very complicated calculations.......For our road going engines 4 to 5ltr, say sub 320bhp, does the single intake pipe provide adequate flow for the occasional 6k blasts and spirited driving or is there room for improvement?
Im curious after recently seeing a number of throttle body conversions, both in the flesh and of course the glorious 5.3 poxon/dom special that's on here.
I except the improved throttle response and probable requirements of air flow on the bigger engines, but, what about lesser engines or cars that don't go racing and so constantly at high rpm?
Heads are generally excepted a restriction on our engines and so just wondering about what would be the 'optimum '??
Im curious after recently seeing a number of throttle body conversions, both in the flesh and of course the glorious 5.3 poxon/dom special that's on here.
I except the improved throttle response and probable requirements of air flow on the bigger engines, but, what about lesser engines or cars that don't go racing and so constantly at high rpm?
Heads are generally excepted a restriction on our engines and so just wondering about what would be the 'optimum '??
In answer to your question yes the plenum does provide enough air, but can fall short at high revs on the 5.0 cars. As a road car no real difference as your not flat out long enough to really starve the engine of air.
Larger throttle body 72 mm as opposed to the standard 65 can be a good mod and help to rush air in there.
Twin or even triple throttle bodied plenum offer quicker pick up response and probably a better flow of air to individual cylinders but only really on highly tuned engines with 350+ Bhp BV heads and ported.
To get the most out of bigger replacement plenum you’d need a tuned engine/ decent Ecu and timing arrangements which make the most of it.
It’s by no means a waste of time but on lessor compression engines more a marginal gain.
Together all these things add up and do add power at higher revs. On its own barely noticeable.
I’ve read in the past the plenum acts as a cooling device for heat to be dispersed up and away from cyl head area so carbon plenum won’t do that, but if it makes any difference is a good question.
For ages I thought the ACT air intake pipe was a rip off, then bought one, coupled with a clean K&N filter, it’s smooth bore nature, thickness which resists heat and the connector pieces that creates a good flow of air as it bends through bodywork, I found this to be a great piece of kit. My engine sounds throaty for a fairly standard engine so it must be right yes
I don’t think a smooth bore elbow does a lot to be honest,,, but I still have one, it all adds up.
Larger throttle body 72 mm as opposed to the standard 65 can be a good mod and help to rush air in there.
Twin or even triple throttle bodied plenum offer quicker pick up response and probably a better flow of air to individual cylinders but only really on highly tuned engines with 350+ Bhp BV heads and ported.
To get the most out of bigger replacement plenum you’d need a tuned engine/ decent Ecu and timing arrangements which make the most of it.
It’s by no means a waste of time but on lessor compression engines more a marginal gain.
Together all these things add up and do add power at higher revs. On its own barely noticeable.
I’ve read in the past the plenum acts as a cooling device for heat to be dispersed up and away from cyl head area so carbon plenum won’t do that, but if it makes any difference is a good question.
For ages I thought the ACT air intake pipe was a rip off, then bought one, coupled with a clean K&N filter, it’s smooth bore nature, thickness which resists heat and the connector pieces that creates a good flow of air as it bends through bodywork, I found this to be a great piece of kit. My engine sounds throaty for a fairly standard engine so it must be right yes
I don’t think a smooth bore elbow does a lot to be honest,,, but I still have one, it all adds up.
Edited by Classic Chim on Sunday 6th October 06:23
Edited by Classic Chim on Sunday 6th October 08:25
Edited by Classic Chim on Sunday 6th October 16:50
Just bear in mind that you can spend a lot of money making very little difference.
The standard TVR set up works fine for road use. Only track days really test the cars, because on track you are averaging much higher speeds for much longer and are constantly on the throttle or brakes.
Also bear in mind that TVR lied.....the standard 5 litre makes 280 bhp at the flywheel, not the claimed 340.
To make them go appreciably faster you either have to spend megabucks naturally aspirated a la Poxon, or go forced induction, which pushes more air in and also costs quite a few thousand by the time you have upgraded brakes, ECU, wheels, tyres (to accommodate bigger brakes).
What you MUST do before you spend your hard earned is ask on here and drive a few cars that have been modified. You might be surprised how good your standard car is, particularly on our crowded U.K. roads.
The standard TVR set up works fine for road use. Only track days really test the cars, because on track you are averaging much higher speeds for much longer and are constantly on the throttle or brakes.
Also bear in mind that TVR lied.....the standard 5 litre makes 280 bhp at the flywheel, not the claimed 340.
To make them go appreciably faster you either have to spend megabucks naturally aspirated a la Poxon, or go forced induction, which pushes more air in and also costs quite a few thousand by the time you have upgraded brakes, ECU, wheels, tyres (to accommodate bigger brakes).
What you MUST do before you spend your hard earned is ask on here and drive a few cars that have been modified. You might be surprised how good your standard car is, particularly on our crowded U.K. roads.
I intentionally kept my 450 to its original capacity having looked at V8D 5 and 5.3's as i felt, to me, the return on investment wasn't there in terms of hp gains, so i choose to stick to 4.6, but maximise/optimise it within the realms of the 'real world'. Ie it's the usual big valve, ported, 72mm plenum etc etc with gems and either a cf tuned manifolds or ACT's
Just curious if the single induction pipe is holding my 300+ lump back a little.
Its highly unlikely (read impossible not going to happen) that id look to go down a throttle body route, just curious to explore different options later down the line. A simease type plenum would gain TWO induction pipes entering the plenum from opposite sides.....surely this must offer a lot to the system - technicalities of the the set up not withstanding.
Just curious if the single induction pipe is holding my 300+ lump back a little.
Its highly unlikely (read impossible not going to happen) that id look to go down a throttle body route, just curious to explore different options later down the line. A simease type plenum would gain TWO induction pipes entering the plenum from opposite sides.....surely this must offer a lot to the system - technicalities of the the set up not withstanding.
I did a test with silicon kid's chimaera which always runs mid 340s hp on my dyno.
he has the ACT smoothbore intake fitted, and I did a back to back test with a straight pipe over the wing ie cool air and no bends/restrictions.
The hp outputs were just about identical between the two tests ... meaning if you've got the ACT induction pipework you're not losing out up to 350hp level anyway. It's fit and forget and great value for money.
he has the ACT smoothbore intake fitted, and I did a back to back test with a straight pipe over the wing ie cool air and no bends/restrictions.
The hp outputs were just about identical between the two tests ... meaning if you've got the ACT induction pipework you're not losing out up to 350hp level anyway. It's fit and forget and great value for money.
spitfire4v8 said:
I did a test with silicon kid's chimaera which always runs mid 340s hp on my dyno.
he has the ACT smoothbore intake fitted, and I did a back to back test with a straight pipe over the wing ie cool air and no bends/restrictions.
The hp outputs were just about identical between the two tests ... meaning if you've got the ACT induction pipework you're not losing out up to 350hp level anyway. It's fit and forget and great value for money.
Ok, cool. he has the ACT smoothbore intake fitted, and I did a back to back test with a straight pipe over the wing ie cool air and no bends/restrictions.
The hp outputs were just about identical between the two tests ... meaning if you've got the ACT induction pipework you're not losing out up to 350hp level anyway. It's fit and forget and great value for money.
It does sound like as good as the carbon double and triple manifolds are, they do seem to be more akin to the 'sport' button you get to press in a lot of modern cars!
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