Carbon Fibre Plenums..... worth the money?

[MPoxon]

Afternoon,

I have been looking at potential upgrades for my Griff and have made the decision to simply improve on what I have without modifying the engine for the time being.

The obvious start for this is 72" Plenum, CF trumpets, heat insulator & ACT smooth bore hoses.

I have seen a number of cars with Carbon Fibre Plenums recently. Purely from an aesthetical point of view I think they look absolutely fantastic. Does anyone have any experience with these and what benefits do you get over the standard 72" & CF trumpet modification?

V8D Single Throttle Plenum


ACT Twin Throttle Plenum


ACT Tripple Throttle Plenum


Matthew

[JR]

Six feet! That's one big plenum. I think that you'll find it's 72mm :-) and this is the crux of the matter: most of the cast plenums will not take a hole that big safely but cast your own in CF and you can make it whatever size you wish - that's what Tim has done.

[spend]

I don't recall that Tims multi-throttles are actually that big when you work out the cross-sectional areas? Much more of the effort was getting good airflow AIUI.

[MPoxon]

JR said:

Six feet! That's one big plenum. I think that you'll find it's 72mm :-)

[JR]

MPoxon said:

Does anyone have any experience with these and what benefits do you get over the standard 72" & CF trumpet modification?

From memory for a standard engine you'd hardly see any benefit, ie too small a difference to measure and even for a tuned engine it would have to be very highly tuned for the triple plenum to be of a benefit. Spend seems to recall a little differently though. Maybe the designs have been revised. If I were you I'd have a chat to Tim directly.

[spend]

The throttle butterfly is only one element of the plenum design, and was all I was commenting on due to the 72mm (mis)quoted by the OP which is what he referred to.

[Richieboy3008]

3 is a bigger number than one so it must be better, so get the triple.

[topsparks]

My 5.5 made 330 BHP on a Group A twin plenum,which I had polished and looked great,but with an Act triple it made 370 BHP!

[roysum]

If you have an airflow meter, there surely would be no benefit ?

[JamesK]

Mine has the triple, although a previous version looking at the current one as mine isn't quite as blingy

I can't give you a before and after comparison sadly but I can say that the throttle response is hilariously good. This may be partly a pre-cat party trick compared to my 500 in fairness.

Hmm, not sure that helps really

[900T-R]

Same here with the twin - great throttle response making a sensibly specced/built 4.x litre engine feel more like an AJP/S6 but with the right sort of noise and low down urge. The carbon fibre shaves a kg or two from the top of the engine assembly too which can't be bad...

[MPoxon]

900T-R said:

Same here with the twin - great throttle response making a sensibly specced/built 4.x litre engine feel more like an AJP/S6 but with the right sort of noise and low down urge. The carbon fibre shaves a kg or two from the top of the engine assembly too which can't be bad...

That is good to know - thanks. I do not really rate the throttle response on mine, I find the pick up very sluggish unless in the correct gear. It may be worth the investment on the grounds of throttle response in that case.

[MPoxon]

JamesK said:

Mine has the triple, although a previous version looking at the current one as mine isn't quite as blingy

I can't give you a before and after comparison sadly but I can say that the throttle response is hilariously good. This may be partly a pre-cat party trick compared to my 500 in fairness.

Hmm, not sure that helps really

That must be the Holly Grail of throttle response 4.5BV + triple plenum!

[SILICONE KID]

You can get a 72mm plenum,45mm trumpet base with short flared aluminuim trumpets and a port matched inet manifold for £450. plus a insultor gasket for £17.50.would that improve a 4l and 4.5.

[roysum]

SILICONE KID said:

You can get a 72mm plenum,45mm trumpet base with short flared aluminuim trumpets and a port matched inet manifold for £450. plus a insultor gasket for £17.50.would that improve a 4l and 4.5.

Yep !

[SILICONE KID]

It seems alot more for your money than a bit of plastic !

[MPoxon]

SILICONE KID said:

You can get a 72mm plenum,45mm trumpet base with short flared aluminuim trumpets and a port matched inet manifold for £450. plus a insultor gasket for £17.50.would that improve a 4l and 4.5.

I did look at the option of replacing the inlet manifold and trumpet base for port matched versions however I understand that to remove and replace the inlet manifold is quite a big job as which will disturb oil and fuel waterways and could even take a TVR specialist up to 5 hours labour. For this reason I was potentially looking at a multi-throttle carbon plenum to maximize the potential of the existing inlet manifold.

You mention that your suggestion would improve a 4l and 4.5l, what would you recommend for a 5l?

[roysum]

MPoxon said:

I did look at the option of replacing the inlet manifold and trumpet base for port matched versions however I understand that to remove and replace the inlet manifold is quite a big job as which will disturb oil and fuel waterways and could even take a TVR specialist up to 5 hours labour. For this reason I was potentially looking at a multi-throttle carbon plenum to maximize the potential of the existing inlet manifold.

You mention that your suggestion would improve a 4l and 4.5l, what would you recommend for a 5l?

Off you go then Daz ! Megasquirt ?

[SILICONE KID]

I have the above on my 5l .V8D supplied and fitted it when they built the engine back up.I can`t help saying it but its making 339bhp can i say it again 339bhp

I can`t see it being that much of a job, just remember to stock up on the Silicone

I thought the 5l came with this setup as standard !

Edited by SILICONE KID on Wednesday 2nd February 20:49

[Alexdaredevilz]

Whilst were all on the topic of plenum upgrades

Would you think welding this on the plenum would have a gain over a 72mm conversion?

As im in several minds on what to do with mine,