Plemun and trumpets
Discussion
clive f said:
I assume the new bellmouths are simply a mouth to fit over the opening in the base, but I may be wrong.
I've seen some pics and they look like they are intended to add 'flares' to the otherwise parallel sided straight cut 500 type tubes. I guess there could well be some effect from them as they will soften what must be some pretty hefty standing wave reflections off the abrupt ends of the standard stacks if nothing else... whether that effect will be beneficial is another story and will prolly depend on your own perceptions of what the power characteristics should ideally be as much as anything 
SC power suggest revising trumpet lengths when fitting the flowed bell mouths. Revising the engine runner lengths changes the breathing harmonics, and when matched to cam specification improvements in volumetric efficiency and filling of the cylinders are achieved. Raising the plenum using the spacer assists by improving air flow to the trumpets and increases air volume within the Plenum to improve throttle response, as intake drag is reduced. It is produced from aluminium to assist heat disipation externally through its wall, upper plenum heat being further reduced by the insertion of a heat insulating gasket between the intake manifold and the trumpet base.
Realistacly, filling of the combustion chambers are improved by approximaly 5% when matched to peak power and torque rpm using revised runner lengths and bell mouths. Its all about getting as much air as possible into the cylinders.
Realistacly, filling of the combustion chambers are improved by approximaly 5% when matched to peak power and torque rpm using revised runner lengths and bell mouths. Its all about getting as much air as possible into the cylinders.
Pupp said:
Still think that is a cracking idea Eliot... do you still have the tooling or was it CNC?
I'm made the tool myself and done it on a 30 year old milling machine!More photos on my rover manifold archive:
http://www.mez.co.uk/ms12.html
eliot said:
Pupp said:
Still think that is a cracking idea Eliot... do you still have the tooling or was it CNC?
I'm made the tool myself and done it on a 30 year old milling machine!More photos on my rover manifold archive:
http://www.mez.co.uk/ms12.html
CHGRIFF said:
It is produced from aluminium to assist heat disipation externally through its wall
Could you clarify how that works? Convention wisdom would say that when you have something you are trying to keep cold (the plenum top) connected to something hot (the trumpet base, heated via the inlet manifold) you use an insulator not a conductor. Making this spacer out of aluminium seems like a massive own goal.
I spoke to Colin Harvey at SC Power (very helpful). There is a 15mm ali spacer between the bottom of the plenum and the trumpet base then a 2mm insulating gasket that fits under the trumpet base. Total 17mm increase in height which should fit under a standard Griff bonnet and give the plenum a capacity of 4.6 litres. The trumpets Colin said he could give an exact length of the inlet tubes to be cut to according to the state of tune of the engine. He said he was planning to offer the service of supplying the tubes already cut to the correct length - which is what I'm waiting for. I assume from the replys so far that no one has done this upgrade? Maybe I will be the first and let you know how it all goes.
GreenV8S said:
CHGRIFF said:
It is produced from aluminium to assist heat disipation externally through its wall
Could you clarify how that works? Convention wisdom would say that when you have something you are trying to keep cold (the plenum top) connected to something hot (the trumpet base, heated via the inlet manifold) you use an insulator not a conductor. Making this spacer out of aluminium seems like a massive own goal.
My 20mm thick spacer is made of a very bad conducting composite just the right thing too use imho
And fits under the bonnet without issue
Pasco said:
GreenV8S said:
CHGRIFF said:
It is produced from aluminium to assist heat disipation externally through its wall
Could you clarify how that works? Convention wisdom would say that when you have something you are trying to keep cold (the plenum top) connected to something hot (the trumpet base, heated via the inlet manifold) you use an insulator not a conductor. Making this spacer out of aluminium seems like a massive own goal.My 20mm thick spacer is made of a very bad conducting composite just the right thing too use imho
And fits under the bonnet without issue
Just been over to Tim's place today (ACT) and noticed that he had recently done a further test into the blended base vs ACT trumpets debate. Based on a 500 Taraka engine, back to back tests were done with the blended base vs the ACT trumpets with no remap (just power runs with each). Here are the results:
The red line is ACT trumpets, the orange is blended base. Note that the BHP is increased overall and slightly at the top end, though the peak is brought a little lower. The torque however sees some good gains across the whole range.
All in all, glad I've got the ACT stuff!
The red line is ACT trumpets, the orange is blended base. Note that the BHP is increased overall and slightly at the top end, though the peak is brought a little lower. The torque however sees some good gains across the whole range.
All in all, glad I've got the ACT stuff!
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