What trumpets?
Discussion
Hello all, sorry for the cross posting from the chim forum but I know a few guys on here have a few mods on their RV8s.
I have ordered a TVR Power modified plenum today via Ian at Torque RVT, has anyone eleso on here gone for the overbored plenum and if so what trumpets have you gone for diameter/length?
Anyone tried a few combinations?
Ian is coming back to me with the reccomended toobs but I thought I would just ask.
Ta Corin
I have ordered a TVR Power modified plenum today via Ian at Torque RVT, has anyone eleso on here gone for the overbored plenum and if so what trumpets have you gone for diameter/length?
Anyone tried a few combinations?
Ian is coming back to me with the reccomended toobs but I thought I would just ask.
Ta Corin
Mine look the same as Quinnys. I dont think they are set height per cylinde and likley just set so teh flares dont touch.
Whilst I could understand that some one may have studied how the air comes into the plenum and the tall ones nearer the entrance may play a part in how the air flows into the lower ones around them?
Prehaps someone can explain ?
BB
Whilst I could understand that some one may have studied how the air comes into the plenum and the tall ones nearer the entrance may play a part in how the air flows into the lower ones around them?
Prehaps someone can explain ?
BB
the trumpets in the middle are longer than the outer ones because, if you look at the inlet manifold intself you will see that the outer ones have a longer route to the ports than the inner ones which are shorter, the trumpets are therefor compensating for this by making the inner ones longer, by fitting taller trumpets than the outer ones, personally I don`t think that the trumpets are helping things at all, the air is sucked into the phlenum, and the trumpets are an obstruction to the airflow, whereas a taraka stlye trumpet base, that has no trumpets at all, with the holes in the base given nice rounded edges will give a much better air flow, but the benefits of this would only be apparent after being rid of the lucas ecu and the airflow meter, hoping to play with this in the autumn.
Clive, now i look again I see exactly what you mean. I also understand what you mean with the plenum base. Would it not be the case that once all cylinders are drawing air flow would be better without trumpets as this might disrupt flow inside the plenum. In open air scenarios like on my Mexico the trumpets are pulling from 'open air' and work a treat but in an enclosed situation????
Happy to be educated by someone who knows best.
Happy to be educated by someone who knows best.
Edited by Bomber Denton on Tuesday 27th March 22:25
I've run lots of cars now with and without trumpets .. there seems to be no general rule either way .. there's no "best option" as far as i can tell .. I have seen strong and weak engines in both configurations. the strongest engine on my dyno on a plenum had a blended trumpet base though if that helps any .. but mongoose's brilliant road 5 litre runs alloy trumpets .. as i say, I've seen no definitive answer one way or the other.
The trumpets improve air flow the bellmouth helps the tube or tract breath, effectively squeezing more air in, trumpets will scavenge air from the side as well as directly above, we've also found that in most cases stand alone trumpets (as in the alloy ones) are more effective for torque than blended bases or airbox backplates
The improvements from fitting trumpets depends on engine spec, especially the cam.
Here's an example: TVR Taraka engine, using blended base (no trumpets) will give you the highest peak bhp, if you fit trumpets to this set up you'll gain torque everywhere exept high rpm, loosing a bit of Peak power, but TVR Power developed this package for top end punch.
Back to back bench dyno tests at V8D on a standard 5.0L saw a small gain everywhere when fitting trumpets compared with standard 5.0L base ( up to 9 lb ft)
It's true that results vary but this gives an indication.
The improvements from fitting trumpets depends on engine spec, especially the cam.
Here's an example: TVR Taraka engine, using blended base (no trumpets) will give you the highest peak bhp, if you fit trumpets to this set up you'll gain torque everywhere exept high rpm, loosing a bit of Peak power, but TVR Power developed this package for top end punch.
Back to back bench dyno tests at V8D on a standard 5.0L saw a small gain everywhere when fitting trumpets compared with standard 5.0L base ( up to 9 lb ft)
It's true that results vary but this gives an indication.
RobPhoboS said:
what do these trumpets actually do ?
I've seen them soo many times on cars are FOS, and thought they looked incredible but NO idea what they are for
I've seen them soo many times on cars are FOS, and thought they looked incredible but NO idea what they are for
It's no doubt a bit more subtle than this, but this is how I see it. Air is elastic stuff. To draw air into the engine, you need to accelerate it smoothly, to avoid simply creating an area of low pressure by drawing on it too hard, because of this elasticity. If you look at the shape of the trumpet you can see how it does this, enabling the engine to pull air in from a greater area than simply that of the tube it's connected to. A blended base achieves similar effects to a trumpet, however it will not work as well around the outer edge as a trumpet does.
Steve.
Edited by Steve_T on Wednesday 28th March 17:37
I'm currently working on my second version of my improved blended trumpet base. I'm hoping to get it dynod to see if it actually works.
For the second version, ive actually made the tooling to cut the flares more consistently:
I also hope to test the 71mm throttle plenum also:
www.mez.co.uk/ms12.html#71mm
For the second version, ive actually made the tooling to cut the flares more consistently:
I also hope to test the 71mm throttle plenum also:
www.mez.co.uk/ms12.html#71mm
eliot said:
I'm currently working on my second version of my improved blended trumpet base. I'm hoping to get it dynod to see if it actually works.
For the second version, ive actually made the tooling to cut the flares more consistently:
I also hope to test the 71mm throttle plenum also:
www.mez.co.uk/ms12.html#71mm
For the second version, ive actually made the tooling to cut the flares more consistently:
I also hope to test the 71mm throttle plenum also:
www.mez.co.uk/ms12.html#71mm
I'm making my mould for blended trumpet bases now, well my second mould as the people i approached a year ago to do it turned out to be less than professional
but the people whi will be making them for me now used to make race parts for the tvr factory race teams as well as F1 teams so i think they'll be a bit more enthusiastic 
ACT said:
The trumpets improve air flow the bellmouth helps the tube or tract breath, effectively squeezing more air in, trumpets will scavenge air from the side as well as directly above, we've also found that in most cases stand alone trumpets (as in the alloy ones) are more effective for torque than blended bases or airbox backplates
The improvements from fitting trumpets depends on engine spec, especially the cam.
Here's an example: TVR Taraka engine, using blended base (no trumpets) will give you the highest peak bhp, if you fit trumpets to this set up you'll gain torque everywhere exept high rpm, loosing a bit of Peak power, but TVR Power developed this package for top end punch.
Back to back bench dyno tests at V8D on a standard 5.0L saw a small gain everywhere when fitting trumpets compared with standard 5.0L base ( up to 9 lb ft)
It's true that results vary but this gives an indication.
The improvements from fitting trumpets depends on engine spec, especially the cam.
Here's an example: TVR Taraka engine, using blended base (no trumpets) will give you the highest peak bhp, if you fit trumpets to this set up you'll gain torque everywhere exept high rpm, loosing a bit of Peak power, but TVR Power developed this package for top end punch.
Back to back bench dyno tests at V8D on a standard 5.0L saw a small gain everywhere when fitting trumpets compared with standard 5.0L base ( up to 9 lb ft)
It's true that results vary but this gives an indication.
Ah ha !
Ok more importantly...
Does it sound better ?
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