ACT plenum twin throttle body

[ClassicChimaera]

Evening gents.
Just wondering who's running any of the ACT Plenums.

Im Interested in the twin throttle body version.

What sort of gains can I expect.
I use 38 mm trumpets but it's suggested you use 45 mm with these so I'll need a re map etc.

Any idea what I should expect from an engine with about 290 Bhp at the moment.

Any thoughts will be appreciated.

Are there other mods I should consider in conjunction with this mod. Cheers Al

[SILICONEKID345HP]

You can also get the twin with larger throttle bodies .

282328341741.Ebay This car with the twin plenum

Edited by SILICONEKID345HP on Thursday 19th January 19:53

[caduceus]

Just been looking at your profile Alun. That car has had some serious wedge spent on it. How much power do you really want from a 4.6? If it's a keeper, wouldn't turbo charging it be a better option? Big turbo but set at a lower boost. Then when you get bored of the power again later on, just up the boost.

If not, a decent port job on the heads and get all mating surfaces matched. Bigger valves? Depends where you want the power and how it's delivered.
I had the 885/435 cam in mine and it didn't 'feel' that fast. My old 4.3 Griff 'felt' quicker, because of how the power was delivered from the old TVR51 cam and longer primary manifolds. But horses for courses I guess.

[SeiW500]

I have one on my car, 4.3 Griff, not sure how much I if any extra GG's it adds as a stand alone mod but mine was added when the previous owner did some other engine mods, more aggressive cams and full engine rebuild/ blueprinted. I've been told by a marque expert that it's now a match for a 500. I don't know how many GG's it's pumping out but it does feel strong.
I'd say you'd need to have some serious work done on your engine to justify fitting this.

Edited by SeiW500 on Thursday 19th January 21:01

[KateV8]

We tried one a few years ago (stage 2 ported heads at the time, fully decatted and ACT manifolds) and if I'm honest it felt like a waste of money. Not decrying anyone else's experience but it just didn't work for us. We had major problems with the throttle sticking open, air leaks around the plenum base due to it being uneven and when it did work the car felt like it had lost some mid range torque over a standard plenum without really gaining anywhere else (and on Canems then too so mapped to optimise the set up). Maybe the triple would have worked but ours was the twin, It was the disappointment of this that led to Kate becoming SC, now THAT really did make a difference .

[ClassicChimaera]

KateV8 said:

We tried one a few years ago (stage 2 ported heads at the time, fully decatted and ACT manifolds) and if I'm honest it felt like a waste of money. Not decrying anyone else's experience but it just didn't work for us. We had major problems with the throttle sticking open, air leaks around the plenum base due to it being uneven and when it did work the car felt like it had lost some mid range torque over a standard plenum without really gaining anywhere else (and on Canems then too so mapped to optimise the set up). Maybe the triple would have worked but ours was the twin, It was the disappointment of this that led to Kate becoming SC, now THAT really did make a difference .

Is your car at Powers at the moment?

Thanks for the responses and im of the same opinion, I'd need other serious engine mods to justify this.

[mk1fan]

Phazed has ACT's triple plenum fitted to his 5.5.

[ClassicChimaera]

I know. It works well,,, but then so does the rest of the car. 5.5,, he probably needs it

It's a bling thing if like me your still below 300 Bhp.

One might be available, I've already indicated I'm not likely to be interested as I really like my car as it is but if I'm going to go for more power even though it'll cost more N/A as a hobby and over time it's sort of more fun to me and this should be part of that equation.

[phazed]

Mathew P has one.

[QBee]

Law of diminishing returns Alun - and you are exactly at that point.

[KateV8]

ClassicChimaera said:

Is your car at Powers at the moment?

Thanks for the responses and im of the same opinion, I'd need other serious engine mods to justify this.

Our car was returned home by us today, she only went for service/mot and brakes and was ready before Christmas but a combination of long working hours and winter flu have prevented her collection till now. It was a happy and joyous reunion, me and wife back with our beloved Chim

[Matthew Poxon]

You can read my ramblings about the ACT twin throttle body plenum here:
https://matthewpoxon.wordpress.com/2014/05/01/act-...

In summary it is not about increased numbers with this mod, at around 1k it is poor value for money if you are looking for power gains. What it does do however is vastly improve the drivability of the car with a lovely crisp throttle response. Very happy with mine. It helps that the aesthetically it looks epic as well

You are more than welcome to take mine for a spin and see what you think.

[QBee]

Matthew Poxon said:

You can read my ramblings about the ACT twin throttle body plenum here:
https://matthewpoxon.wordpress.com/2014/05/01/act-...

In summary it is not about increased numbers with this mod, at around 1k it is poor value for money if you are looking for power gains. What it does do however is vastly improve the drivability of the car with a lovely crisp throttle response. Very happy with mine. It helps that the aesthetically it looks epic as well

You are more than welcome to take mine for a spin and see what you think.

Our first "ole pals" track day this Spring should be a lot of fun. Looking forward to it.

[ClassicChimaera]

phazed said:

Mathew P has one.

He's also got good exhausts
And many other goodies

It's quite expensive for what I'll achieve on my engine I feel, if I as Mk1fan points out, I get heads etc sorted then this would be the icing,,,

ive just looked at my profile, terrible waste of cash,,, if you spread it over say 15 years of steady Eddie driving
It's cheap,,, I hope

I dunno if you've noticed but I do rattle on about how good it drives,,, I should think so.
I haven't even done the chassis yet and we're at 20 million bucks but you can't take the stuff with you so as I enjoy the car so immensely it's worth every dime.

I'll finish it properly one day and it will be all worth it. I'm close to pulling the body,, I've been chatting up a couple of good mechanic friends to help out disconnecting and lifting the body off. If I hadn't put them mad bad tyre's on I'd do it this week,, but they are so good I can't stop ,,,,, Testing them

Truth is I'm going to drive it through every condition I dare until the riggers are annoying me enough then do a considered job.
I have a mate who's been welding Stockcar chassis for years and his welds are like art. I showed him the chassis and he fell in love with it. Reckons it's strong for s few years yet,, but I'm not convinced.
I want a stronger Chassis.

[ClassicChimaera]

I drove for 24 hrs,,, stupid thing to do but I did have breaks,,,, not because I had to but because I wanted too, and I was comfortable too. At night on my own across mid France, imagining what it was like for some lone fighter pilot and just his Merlin for company, that steady burble and vibration but assurance that fills you with life and will to get somewhere!
Memories are made from events you maximise. Fantastic day in my life I'll never forget.
Brilliant car, it served me with illicit ease.

See it seems well cheap now doesn't it

[Matthew Poxon]

KateV8 said:

We tried one a few years ago (stage 2 ported heads at the time, fully decatted and ACT manifolds) and if I'm honest it felt like a waste of money. Not decrying anyone else's experience but it just didn't work for us. We had major problems with the throttle sticking open.

I agree with the point on the sticky throttle, it seemed to be a common theme when I spoke to owners who had these fitted. I had a conversation with Tim at ACT about this before I bought mine, in summary I told him I loved the product but the throttle linkage design is a bit wk, it clearly does not match the same high quality of the rest of the product. Tim did say that he was planning to improve the product by possibly fitting a Jenvey linkage to the throttle bodies but so far had not got around to it due to other commitments. I said to Tim if you can supply me a plenum with the new linkage I will buy one. You have to hand it to him Tim at ACT is awesome, if I was him I would have probably told be to either buy the plenum off the shelf as is or piss of and don't buy it. Less than a month later Tim had a prototype built and fully tested at Austec on their rolling road. Soon after I had the first plenum with the new linkage fitted and working like a dream. The new linkage gives a really nice smooth throttle travel.

Existing Linkage:


Jenvey Linkage

[QBee]

ClassicChimaera said:

I want a stronger Chassis.

Sportmotive sell one..... expensive link

[ClassicChimaera]

KateV8 said:

Our car was returned home by us today, she only went for service/mot and brakes and was ready before Christmas but a combination of long working hours and winter flu have prevented her collection till now. It was a happy and joyous reunion, me and wife back with our beloved Chim

I dropped mine at Powers yesterday for some ball joints to be fitted. Looking filthy!

Yours a beautiful shocking thing. I could tell she was looking out for you bit lonely she was,
What a wonderful job you've done.

It's only been two days but there's a gaping hole in my life,,, I'm up,super early to get work done just so I can be there early to collect her. Mad but true.

[ClassicChimaera]

Matthew Poxon said:

You can read my ramblings about the ACT twin throttle body plenum here:
https://matthewpoxon.wordpress.com/2014/05/01/act-...

In summary it is not about increased numbers with this mod, at around 1k it is poor value for money if you are looking for power gains. What it does do however is vastly improve the drivability of the car with a lovely crisp throttle response. Very happy with mine. It helps that the aesthetically it looks epic as well

You are more than welcome to take mine for a spin and see what you think.

I'll read this with joy tomorrow Matt.
Yeah, you can check out the super responsive MBE,,, be careful though it's very powerful.
I'd like to see Peters true classic so maybe meet up somewhere and end up at his for a brew.

[phazed]

Matthew, mine is one of the first triple plemuns and has similar linkage to your original one by the looks of it.

Mine has never stuck once so this must be a feature of the twin plenum possibly.