ACT Trumpets vs. shortened OE ones (430)?

[900T-R]

Any functional (aerodynamic) difference between the two options and if yes and providing this were to be the only induction mod apart from a smooth bore AFM-plenum hose and heat insulating/reflecting sleeving, would you fork out the £200ish for the former?

[Woody_450]

I went the route of the ACT trumpets, along with the air intake sleeving and plenum heat gasket thing, look here

From just doing these mods it made the car feel a lot better to drive, I don't have any physical data evidence to back this up, no RR sessions etc.

I do know that the ACT ones are actually longer than the standard trumpets, it was a complete sod to get the plenum back on

There seems to be a lot of people on here that have gone down the cut down trumpets so I would assume someone will be along soon with far more knowledge about the correlation between trumpet length and possible power gains and losses.

Rich

[ACT]

900T-R said:

Any functional (aerodynamic) difference between the two options ?

The shortened standard trumpets (as fitted to 4.3 & 4.5 TVRs) only offer more air at high rpm which equates to small increase in peak bhp, as they give more clearance to plenum roof.
The carbon fibre trumpets improve torque throughout the rev range, as they are tapered with bell mouths and 10mm wider at the top, they are 10mm shorter than standard & about 15mm longer than the TVR shortened trumpets.
We have a back to back dyno graph TVR short trumpets V Carbon superflares here : www.actproducts.co.uk/performance.

[900T-R]

Woody_450 said:

I do know that the ACT ones are actually longer than the standard trumpets

ACT said:

The shortened standard trumpets (as fitted to 4.3 & 4.5 TVRs)

If I understand the both of you correctly, this means my 4.3 already has 25 mm shortened trumpets and it's only the four-ohs that would benefit (slightly) from cutting the ones that are in there?

Ta, Eric

[aerospoke]

No he says his trumpets will give you more power at lower rpms. This should be visible in the dynograph in the link, that does not work for me! The graph shows a comparison between the shorter original trumpets and the ACT ones.

Cheers Jens

[900T-R]

aerospoke said:

No he says his trumpets will give you more power at lower rpms.

That I understand, but are the trumpets in the 4.3 & 4.5 'factory shortened' compared to those in the 4.0 (OE Rover I suppose), or does the graph show the difference with a car that had its trumpets cut shorter?

[ACT]

The graph is for shortened trumpets V carbon fibre.

The short ones were fitted to TVR Rover engines 4.3 & 4.5

Tim

[900T-R]

OK forgive me for being thick - but then the OE spec for trumpets is as follows:

4.0 & 4.0 HC: Rover
4.3 & 4.5: Rover, 25 mm shortened
5.0: 44 mm bore TVR

?

[ACT]

900T-R said:

OK forgive me for being thick - but then the OE spec for trumpets is as follows:

4.0 & 4.0 HC: Rover
4.3 & 4.5: Rover, 25 mm shortened
5.0: 44 mm bore TVR

?

Spot on.

[900T-R]

Thank you, Sir!