Plenum Base- Blended or Trumpet
Discussion
Was planning on either blending my plenum base or getting my existing straight pipes flared into trumpets and leave them the same length or possibly cut them down? As after market ones seem to be shorter?
Was wondering which would be the best option? 1997 Griff 500, looking to get a 72mm plenum soon as well. Thanks
Was wondering which would be the best option? 1997 Griff 500, looking to get a 72mm plenum soon as well. Thanks
Fat Griff said:
Was planning on either blending my plenum base or getting my existing straight pipes flared into trumpets and leave them the same length or possibly cut them down? As after market ones seem to be shorter?
Was wondering which would be the best option? 1997 Griff 500, looking to get a 72mm plenum soon as well. Thanks
Why do you need more power Was wondering which would be the best option? 1997 Griff 500, looking to get a 72mm plenum soon as well. Thanks
V8 Villain recons you have a job dealing with what you have now 
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Check out my post at the bottom of this page for dyno numbers on a taraka 500... I'd go with superflare trumpets personally
Check out my post at the bottom of this page for dyno numbers on a taraka 500... I'd go with superflare trumpets personally
until you get rid of the AFM by fitting an aftermarket ecu, you wont see any performance increases anyway, I went from standard tvr pipes to carbon trumpets and have found no noticable difference at all, but will be fitting one of eliots blended bases in the next week or so, and doing some back to back tests to see what it does when running on a better ecu.
the best mod to do while still using the lucas set up is the smooth bore elbow between the afm and the plenum.
not forgetting the insulator plate under the trumpet base.
the best mod to do while still using the lucas set up is the smooth bore elbow between the afm and the plenum.
not forgetting the insulator plate under the trumpet base.
Edited by clive f on Wednesday 7th May 19:27
Fat Griff said:
Funny! Ha Ha Ha, on a serious note i would like peoples opinions on my original question, please. By the way, washed your car yet Pasco!? LOL
Blimey that smiley reminds me of you Hayden for some strange reason
Are you working this Sunday Hayden ?
Edited by Pasco on Wednesday 7th May 21:07
It's like this:
on a typical healthy 500, trumpets over TVR steel tubes are worth around 5-8 bhp and similar torque gains so only a tiny percentage but a gain none the less.
On same engine trumpets over blended base will give much bigger midrange torque gains but little peak BHP gain, the blended base will offer slightly higher peak rpm but in real terms will produce less overall power, one of our graphs was recently posted to show this but not sure where it is.
Here's the thing. on a very highly tuned engine 350 +bhp the blended base will offer more peak power over trumpets, but again less torque in the midrange.
Judging these mods by driving alone is difficult, sometimes by removing midrange torque the car can feel quicker as you have more of a "turbo power curve", but in my book overall torque is king.
Tim ACT
on a typical healthy 500, trumpets over TVR steel tubes are worth around 5-8 bhp and similar torque gains so only a tiny percentage but a gain none the less.
On same engine trumpets over blended base will give much bigger midrange torque gains but little peak BHP gain, the blended base will offer slightly higher peak rpm but in real terms will produce less overall power, one of our graphs was recently posted to show this but not sure where it is.
Here's the thing. on a very highly tuned engine 350 +bhp the blended base will offer more peak power over trumpets, but again less torque in the midrange.
Judging these mods by driving alone is difficult, sometimes by removing midrange torque the car can feel quicker as you have more of a "turbo power curve", but in my book overall torque is king.
Tim ACT
ACT said:
On same engine trumpets over blended base will give much bigger midrange torque gains but little peak BHP gain, the blended base will offer slightly higher peak rpm but in real terms will produce less overall power, one of our graphs was recently posted to show this but not sure where it is.Tim ACT
Presumably your testing was against the taraka blended base, rather than my take on that idea by using a peice of nylon?I suspect that it will be better than a blended base alone, but not as good as trumpets for the mid range torque.
I agree with Tim ACT, efficient trumpets win every time. The scaffolding poles originally specified are a very crude design, are cheap and met TVR's performance objectives. Blending the base as Taraka seems to give an improvement over the standard chimney's, that cant be difficult. The downside is by shortening the effectve runner length by elimiating the intake tubes peak torque and power move down the rpm range away from peak power/torque rpm objectives. This will be detrimental to the intake harmonics and probrably lead to a loss of power in the region of 2-3%. Best to stick to flared trumpets supplied by ACT or SC Power to improve overall volumetric efficiency. The Plenum volume for TVR's is too small and should be by design 1-1.5 times engine capacity, If I understand correctly the Nylon blended base being inserted is on top and in addition to the trumpet base, this leading to further reduction of internal plenum volume probrably in exces of .5 litres. This can only be bad news for performance and engine throttle response. Best to increase the plenum volume and use bell mouth trumpets if possible.
CHGRIFF said:
The Plenum volume for TVR's is too small and should be by design 1-1.5 times engine capacity, If I understand correctly the Nylon blended base being inserted is on top and in addition to the trumpet base, this leading to further reduction of internal plenum volume probrably in exces of .5 litres. This can only be bad news for performance and engine throttle response.
Yes my nylon part does sit on top of the base. It measures 315x120x25, which gives 945cc - so nearly 1L lost.CHGRIFF said:
Best to increase the plenum volume and use bell mouth trumpets if possible.
Has anyone tried this? - I dont see that it would be particulary hard to make sheetmetal plenum lid for the std rover base.Just filled an old plenum lid up with water it took 3L - plus about another 1L in the base part i guess.
Edited by eliot on Saturday 10th May 12:54
eliot said:
CHGRIFF said:
Best to increase the plenum volume and use bell mouth trumpets if possible.
Has anyone tried this? - I dont see that it would be particulary hard to make sheetmetal plenum lid for the std rover base.Plenum volume alone makes a very small difference, we've been making larger single throttle plenums for 11 years, tried everthing from taller extended standard units to wider carbon versions, using the same size throttle comparisons resulted in very small gains.the wider plenums do offer slightly better results due to more space from trumpet to plenum wall.
You will get lots of different opinions in this market and there are lots of new products, although nothing is really "new", people like John Eales, V8 Developments, Castle race, TVR Power, NGK etc have tried everything.
It's all fun though but can be time consuming and good luck to anybody trying their own mods.
You will get lots of different opinions in this market and there are lots of new products, although nothing is really "new", people like John Eales, V8 Developments, Castle race, TVR Power, NGK etc have tried everything.
It's all fun though but can be time consuming and good luck to anybody trying their own mods.
Why is the Rover plenum around 4 litres for their 4.0 litre engine? At the time they had the resource and money to get it right! They could have reduced the plenum volume to save weight and cost. Originally their torque and power requirment would be different to TVR performance objectives with Land Rovers weighing about 2 tonnes and torque being more important. Why reduce the plenum volume when there are better options to improving the poor design and volumetric effiiency of the 5.0l. Ask John Eales if there is an advantage to removing the trumpets, I dont think he does it and he doesn't miss a trick. Proper trumpets win every time.
A few stimulating thoughts on the plenum spacer being manufactured from Aluminium, a superb conductive material. The trumpet base and intake manifold need to be as cool as possible and not a lot can be done about the manifold other than using good insulating gaskets to the cylinder head. If the maifold and trumpet base are hot, this is very detrimental to the intake air temperature as it is warmed through the ducting reducing thermal efficiency. The intake air must be kept as cool as possible. This is the reason for Rover to choose aluminium for their Plenum top, it absorbes heat over a large surface area from the trumpet base and manifold, the heat is then disipated via the plenum top being cooled by external air flow through the engine bay. If you manufactured the spacer from other non metalic materials the plenum top would not work efficiently as heat absorbtion would be restricted due to the insulating factor of the spacer. The result would be excess heat staying within the trumpet base and warming all air flow. Not a good idea. Lets give Rover credit for a superb intake design, it's a pity TVR never took full advantage of the design. Sorry went on a bit here after a late evening glass of wine. Good luck to all those who try to re-invent the square wheel.
A few stimulating thoughts on the plenum spacer being manufactured from Aluminium, a superb conductive material. The trumpet base and intake manifold need to be as cool as possible and not a lot can be done about the manifold other than using good insulating gaskets to the cylinder head. If the maifold and trumpet base are hot, this is very detrimental to the intake air temperature as it is warmed through the ducting reducing thermal efficiency. The intake air must be kept as cool as possible. This is the reason for Rover to choose aluminium for their Plenum top, it absorbes heat over a large surface area from the trumpet base and manifold, the heat is then disipated via the plenum top being cooled by external air flow through the engine bay. If you manufactured the spacer from other non metalic materials the plenum top would not work efficiently as heat absorbtion would be restricted due to the insulating factor of the spacer. The result would be excess heat staying within the trumpet base and warming all air flow. Not a good idea. Lets give Rover credit for a superb intake design, it's a pity TVR never took full advantage of the design. Sorry went on a bit here after a late evening glass of wine. Good luck to all those who try to re-invent the square wheel.
CHGRIFF said:
Why is the Rover plenum around 4 litres for their 4.0 litre engine? At the time they had the resource and money to get it right! They could have reduced the plenum volume to save weight and cost. Originally their torque and power requirment would be different to TVR performance objectives with Land Rovers weighing about 2 tonnes and torque being more important. Why reduce the plenum volume when there are better options to improving the poor design and volumetric effiiency of the 5.0l. Ask John Eales if there is an advantage to removing the trumpets, I dont think he does it and he doesn't miss a trick. Proper trumpets win every time.
A few stimulating thoughts on the plenum spacer being manufactured from Aluminium, a superb conductive material. The trumpet base and intake manifold need to be as cool as possible and not a lot can be done about the manifold other than using good insulating gaskets to the cylinder head. If the maifold and trumpet base are hot, this is very detrimental to the intake air temperature as it is warmed through the ducting reducing thermal efficiency. The intake air must be kept as cool as possible. This is the reason for Rover to choose aluminium for their Plenum top, it absorbes heat over a large surface area from the trumpet base and manifold, the heat is then disipated via the plenum top being cooled by external air flow through the engine bay. If you manufactured the spacer from other non metalic materials the plenum top would not work efficiently as heat absorbtion would be restricted due to the insulating factor of the spacer. The result would be excess heat staying within the trumpet base and warming all air flow. Not a good idea. Lets give Rover credit for a superb intake design, it's a pity TVR never took full advantage of the design. Sorry went on a bit here after a late evening glass of wine. Good luck to all those who try to re-invent the square wheel.
The rover intake a superb design?A few stimulating thoughts on the plenum spacer being manufactured from Aluminium, a superb conductive material. The trumpet base and intake manifold need to be as cool as possible and not a lot can be done about the manifold other than using good insulating gaskets to the cylinder head. If the maifold and trumpet base are hot, this is very detrimental to the intake air temperature as it is warmed through the ducting reducing thermal efficiency. The intake air must be kept as cool as possible. This is the reason for Rover to choose aluminium for their Plenum top, it absorbes heat over a large surface area from the trumpet base and manifold, the heat is then disipated via the plenum top being cooled by external air flow through the engine bay. If you manufactured the spacer from other non metalic materials the plenum top would not work efficiently as heat absorbtion would be restricted due to the insulating factor of the spacer. The result would be excess heat staying within the trumpet base and warming all air flow. Not a good idea. Lets give Rover credit for a superb intake design, it's a pity TVR never took full advantage of the design. Sorry went on a bit here after a late evening glass of wine. Good luck to all those who try to re-invent the square wheel.
Sorry chap but it could have done quite a bit better;
ports 4,6 & 8 all have a double Kink to pull them into an undersized plenum so reducing flow
the throttle is undersized,
The std trumpets are masked by the proximity of the plenum top
The walls of the std plenum are too close to the trumpets so reducing flow
The trumpets are set for peak power at 5200Rpm
Also in TVR's the underbonnet temps is high as the plastic bodywork insulates everything nicely so there is very little in the way of cooling air rushing over the plenum I'm afraid, the plenum is cooled by the air rushing through it which then goes into your engine.
Not helpful for power output or pre-ignition
As for TVR never taking advantage of this intake, it holds the 4.5 and 5.0ltr back quite considerably I've always thought TVR should have produced their own RV8 heads and intake instead of going down the own engine route, they'd have had 400Bhp easily and reliably.
Matt
350Matt said:
CHGRIFF said:
Why is the Rover plenum around 4 litres for their 4.0 litre engine? At the time they had the resource and money to get it right! They could have reduced the plenum volume to save weight and cost. Originally their torque and power requirment would be different to TVR performance objectives with Land Rovers weighing about 2 tonnes and torque being more important. Why reduce the plenum volume when there are better options to improving the poor design and volumetric effiiency of the 5.0l. Ask John Eales if there is an advantage to removing the trumpets, I dont think he does it and he doesn't miss a trick. Proper trumpets win every time.
A few stimulating thoughts on the plenum spacer being manufactured from Aluminium, a superb conductive material. The trumpet base and intake manifold need to be as cool as possible and not a lot can be done about the manifold other than using good insulating gaskets to the cylinder head. If the maifold and trumpet base are hot, this is very detrimental to the intake air temperature as it is warmed through the ducting reducing thermal efficiency. The intake air must be kept as cool as possible. This is the reason for Rover to choose aluminium for their Plenum top, it absorbes heat over a large surface area from the trumpet base and manifold, the heat is then disipated via the plenum top being cooled by external air flow through the engine bay. If you manufactured the spacer from other non metalic materials the plenum top would not work efficiently as heat absorbtion would be restricted due to the insulating factor of the spacer. The result would be excess heat staying within the trumpet base and warming all air flow. Not a good idea. Lets give Rover credit for a superb intake design, it's a pity TVR never took full advantage of the design. Sorry went on a bit here after a late evening glass of wine. Good luck to all those who try to re-invent the square wheel.
The rover intake a superb design?A few stimulating thoughts on the plenum spacer being manufactured from Aluminium, a superb conductive material. The trumpet base and intake manifold need to be as cool as possible and not a lot can be done about the manifold other than using good insulating gaskets to the cylinder head. If the maifold and trumpet base are hot, this is very detrimental to the intake air temperature as it is warmed through the ducting reducing thermal efficiency. The intake air must be kept as cool as possible. This is the reason for Rover to choose aluminium for their Plenum top, it absorbes heat over a large surface area from the trumpet base and manifold, the heat is then disipated via the plenum top being cooled by external air flow through the engine bay. If you manufactured the spacer from other non metalic materials the plenum top would not work efficiently as heat absorbtion would be restricted due to the insulating factor of the spacer. The result would be excess heat staying within the trumpet base and warming all air flow. Not a good idea. Lets give Rover credit for a superb intake design, it's a pity TVR never took full advantage of the design. Sorry went on a bit here after a late evening glass of wine. Good luck to all those who try to re-invent the square wheel.
Sorry chap but it could have done quite a bit better;
ports 4,6 & 8 all have a double Kink to pull them into an undersized plenum so reducing flow
the throttle is undersized,
The std trumpets are masked by the proximity of the plenum top
The walls of the std plenum are too close to the trumpets so reducing flow
The trumpets are set for peak power at 5200Rpm
Also in TVR's the underbonnet temps is high as the plastic bodywork insulates everything nicely so there is very little in the way of cooling air rushing over the plenum I'm afraid, the plenum is cooled by the air rushing through it which then goes into your engine.
Not helpful for power output or pre-ignition
As for TVR never taking advantage of this intake, it holds the 4.5 and 5.0ltr back quite considerably I've always thought TVR should have produced their own RV8 heads and intake instead of going down the own engine route, they'd have had 400Bhp easily and reliably.
Matt
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