Independent runner inlet manifold

Independent runner inlet manifold

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ChimpOnGas

9,637 posts

178 months

Friday 3rd February 2017
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eliot said:
My late friend who had a Griff 500 bought a thor plenum with the idea of doing the dual throttle bodies idea about 10 years ago (those photos on my site are of the actual unit we bought) After taking a look at it, we decided against it and went with carbon trumpets and 72mm plenum. I cant recall if he ever placed it on the engine to check the clearance, i think (knowing what he was like) he had checked that it would clear a griff bonnet.

There's no doubt it will increase the driveability due to the characteristics of the manifold BUT only if you keep the single OEM throttle body - I think going with dual throttles bodies will result in making it worse though, the "tip-in" i.e just of idle response will be worse as you have two throttles opening up and resulting in a drop in air velocity and probably back to shunting issues again.


Will it restrict top end performance ? Given that most Griff 500's struggle to make much over 280 bhp, I dont think it's going to impact on the smaller largely bone stock 4.0 engine which was fitted with this manifold anyway.


Jonathan Douglas of JE Engineering commented on this manifold:
The throttle body has a 68 mm throttle as standard and again, we often take this out, in this case to 71.5 mm. The Thor manifold, when used with either a standard cam or a mildly tuned cam, gives a strong torque peak at around 2,000 rpm, much higher than that achievable with the Lucas plenum design, but even with careful gas-flow work the power is limited. We find it difficult to achieve more than around 280 bhp with this manifold, where a similar amount of effort on a Lucas Plenum manifold will yield 320 bhp (but with less torque below 3,500 rpm

So if he can get 280bhp out of the manifold with a 71.5 throttle body, making it a dual throttlebody is not going to add much and probably take away driveability - unless you are talking about fitting a pair of ~45mm bodies i guess.

Couple of other points:
1) The idle air bypass is different for the hotwire, you either need to drive the OEM thor idle valve with an aftermarket ECU or plumb the OEM hotwire idle valve inline somehow.
2) The fuel rail is 'dead-headed' - which means there's no regulator on the fuel rail. So you either need to weld a fitting on the end and fit a regulator or I believe it's possible to fit the hotwire fuel rail with a bit of bending and forcing.
3) there's no vacuum nipple - so if you are still using a crappy vacuum advance distributor you will need to fit one (or better bin it and go trigger wheel)

edit;
I've owned range rovers with the hotwire and the later thor manifold and the difference is noticeable in terms of low end torque and driveability in a P38. In a TVR it will probably feel like you have dropped a big block chevy in.

Edited by eliot on Friday 3rd February 12:44
Thanks Eliot, I am not a fan of the twin throttle body idea, I followed the guy who's trying to do this on a Marcos and for me it looked like a blind aly, the Thor manifold design tempts us in this direction but I think it's a mistake, a single throttle body is the way to do this but modifications are clearly required to allow the TVR bonnet to shut.

I run the Canems system so no distributor, this system manages idle via the common Bosch 2 wire idle control valve which can easily be plumbed in substituting the Thor unit. A limit of 280hp is just fine with me as my 4.0 litre is comfortably under this figure, the drivability benefit on the other hand is very much in line with my design brief for my Chimaera.

The OP has contacted me by PM and we are making our plans, as a professional toolmaker by trade he introduces valuable skills to the project and his access to a fully equipped machine shop will no doubt prove invaluable.

Let's see if we can make the Thor inlet manifold idea work on my Canems equipped dual fuel TVR Chimaera?

Boosted LS1

21,165 posts

259 months

Friday 3rd February 2017
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^ Lpg and turbo's would be exciting. A marriage made in heaven.

Once upon a time I tried to get dual fuel injectors from Melbourne but they never seemed to reach production and my dream faded. My other idea was to use a holley to provide the throttle plates and emergency fuel bowls for when the lpg ran out but back then electronic control of lpg injectors wasn't available and I waited and waited... I didn't want a cooker ring stuck on top of the carb, doh. It was also hard to get a donut tank but I decided to put the petrol tank in the spare wheel well and an lpg tank across the rear bulkhead.

It could still happen but with LS power. I've always like lpg.

ChimpOnGas

9,637 posts

178 months

Friday 3rd February 2017
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Boosted LS1 said:
^ Lpg and turbo's would be exciting. A marriage made in heaven.

Once upon a time I tried to get dual fuel injectors from Melbourne but they never seemed to reach production and my dream faded. My other idea was to use a holley to provide the throttle plates and emergency fuel bowls for when the lpg ran out but back then electronic control of lpg injectors wasn't available and I waited and waited... I didn't want a cooker ring stuck on top of the carb, doh. It was also hard to get a donut tank but I decided to put the petrol tank in the spare wheel well and an lpg tank across the rear bulkhead.

It could still happen but with LS power. I've always like lpg.
LPG is a highly underrated fuel, at 110 Ron it's also amazingly resistant to detonation,one if the downsides though is it's energy density by mass.

With these facts in mind forced induction becomes a no brainer.

Boosted LS1

21,165 posts

259 months

Friday 3rd February 2017
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And you get very little oil contamination.

eliot

11,363 posts

253 months

Saturday 4th February 2017
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Trying to find out more about this one:


http://www.v8forum.co.uk/forum/viewtopic.php?p=111...

He says its worked out 40mm lower than the hotwire.

ChimpOnGas

9,637 posts

178 months

Saturday 4th February 2017
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eliot said:
Trying to find out more about this one:


http://www.v8forum.co.uk/forum/viewtopic.php?p=111...

He says its worked out 40mm lower than the hotwire.
Interesting scratchchin

mk1fan

10,507 posts

224 months

Saturday 4th February 2017
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Hhhhmmmm. Interesting. What about adding it to a 3.5 with 14CU?

carsy

3,018 posts

164 months

Saturday 1st July 2017
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Anybody progressed this Thor manifold idea. scratchchin


carsy

3,018 posts

164 months

Sunday 2nd July 2017
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That throttle body cant be a million miles of fitting under the bonnet.

Anyone know of one they can measure.




RobXjcoupe

Original Poster:

3,151 posts

90 months

Sunday 2nd July 2017
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I was ready to do any machining/mod/ prototype work but it never went anywhere

ChimpOnGas

9,637 posts

178 months

Tuesday 4th July 2017
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RobXjcoupe said:
I was ready to do any machining/mod/ prototype work but it never went anywhere
With my Chimaera running like a Swiss watch I became distracted by frivolous things like simply driving and enjoying the car, if I had the time I think the Thor manifold might make an interesting winter project but given it's a time consuming experiment that could possibly just end up producing a power delivery that didn't suit the car.... the truth is I kind of lost interest.

Running a 20 year old TVR means holding a slush fund for general maintenance, I'd rather hold my money back for that than go investing in what might potentially reveal itself to be a red herring project. The clincher for me is the manifold arrangement you consistently see on all modern V8s is the sealed plenum crossover with a single throttle body, quite clearly this is the accepted way for OEMs to deliver great drivability without penalizing top end breathing.

We see the same design time and time again offered by Maserati, Ford, Chevrolet and Jaguar to name but a few and I can't think of anybody currently offering a separated super long runner effort like the Thor. I suspect the development work has already been done so I'm reluctant to repeat the experiments using a setup that's been resigned to the history books, sadly all the evidence suggests the outcome will be more disappointing than be groundbreaking.

I have however recently been made aware of an LS style inlet manifold for the Rover V8 that will become available some time in the future, so that may be another reason I kinda lost interest in whole Thor idea which at the end of the day is a design that closely resembles Lloyd Specialist Developments manifold which they now themselves admit may have been a step in the wrong direction.

It's a shame really as doing anything with a naturally aspirated Rover V8 to significantly increase its power output works out expensive and a used Thor manifold can be had quite cheaply, if we ran a Chevy or Ford V8 things would be very different. We wouldn't even be having this discussion as there's a huge industry built around those engines so economies of scale kick in very nicely indeed, all we really need is a cost effective 350-400hp naturally aspirated upgrade that drops right in, and word on the street is that's something already in the making wink



RobXjcoupe

Original Poster:

3,151 posts

90 months

Tuesday 4th July 2017
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No worries wink

ChimpOnGas

9,637 posts

178 months

Tuesday 4th July 2017
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RobXjcoupe said:
No worries wink
I'm still tempted really wink

Dominic TVRetto

1,375 posts

180 months

Thursday 6th July 2017
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Dividing the plenum into 2 *taking all runners to the same bank* is inherently flawed - just think of the fitting order.

The crossplane crank V8 "burble" is caused because each bank has a pair of cylinders that fire consecutively at a given point in the firing order, and these exhaust pulses are collected by bank - the consecutive pulses audible as a stronger combined pulse, which creates the characteristic sound.

Ie. the banks do not fire LRLRLRLR, rather LRRLRLLR

The aim of separating the plenum into 2 (with our long-duration cams that allow spent charge back into the plenum and contaminate the fresh) is to combine runners from alternately-firing cylinders into groups in order to minimise the effect of the spent charge contaminating each plenum - in a similar manner that you would expect in basic exhaust pulse tuning (think how Clive F's bundle-of-snakes manifold works).

This means that a each plenum of a dual plane manifold system will contain runners to both banks (in the correct order) to ensure the alternate spacing within the firing order is achieved - not all runners to the same bank.

If you don't separate the runners alternatively through the firing order - you will get the same contamination problem as in the hotwire plenum.

So just dividing the plenum into 2 separate plenums, each connected to a single bank, will most likely have exactly the same issues as the current single plenum.

My gut feel on why Thor was developed is to provide the easiest solution to packaging the long runners (extra length complementing the low-down torque stump pulling cam) and nothing to do with driveability - range rovers don't suffer this shunting issue because the standard cam has little overlap, so don't suffer from exhaust gas reversal into the plenum anyway.

Taking the "Clive F's manifold" analogy further, I have wondered whether a cut price alternative to the pricy individual throttle bodies solution might be to create an intake manifold that paired up runners from cylinders that were opposed within the firing order (ie. 4 pairs), each connected to a throttle body - so 4 throttle bodies, each serving an opposed pair of cylinders.

Don't know if it would save much, just a thought...

Edited by Dominic TVRetto on Thursday 6th July 09:07

RobXjcoupe

Original Poster:

3,151 posts

90 months

Thursday 6th July 2017
quotequote all
I think the original plan was to get a Thor manifold working on a tvr installation and measure its torque and real time drivability. Mentioned above was a max 280bhp using the Thor manifold but it's toque measurements seem to be overlooked.
The idea that not all tvr owners drive their rv8 engines cars at max rpm on every gear change, so to do an inlet mod with factory available parts that increases torque in the rev range that a majority of drivers naturally drive to would or could have been a good alternative to increased capacity.
That was the theory at least

drlloyd

145 posts

192 months

Thursday 6th July 2017
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If you look closely at the standard Rover V8 EFI intake base you will see that two of the ports from each bank cross to the opposite side - making the intake base dual-plane. If you then divide the top section straight down the middle you will then make a dual plane intake manifold. It is seems as though Rover had this in mind all along but never followed through with this option.
We took advantage of this fact with our Lloyd Dual-Plane intake manifold. This greatly improves throttle response but the Rover V8 engine is far too cylinder head restricted for any intake modifications to make any significant difference to power output.
Kind regards, Daniel Lloyd

Dominic TVRetto

1,375 posts

180 months

Thursday 6th July 2017
quotequote all
RobXjcoupe said:
I think the original plan was to get a Thor manifold working on a tvr installation and measure its torque and real time drivability. Mentioned above was a max 280bhp using the Thor manifold but it's toque measurements seem to be overlooked.
The idea that not all tvr owners drive their rv8 engines cars at max rpm on every gear change, so to do an inlet mod with factory available parts that increases torque in the rev range that a majority of drivers naturally drive to would or could have been a good alternative to increased capacity.
That was the theory at least
The torque "increase" is due to the longer runners - but understand that runner length merely optimises the torque for a particular rpm (long = low rpm torque, short = torque at high rpms).

As such it is not increasing torque per se, but helping improve torque at low rpms by shifting it from elsewhere (ie. from higher rpms where it is now) - it won't magically create more "down low" in addition to what you already have.

However this would have to be coupled with running a cam designed for low rpms, eg original range rover cam - or you will have *mismatched cam vs runner characteristics*, giving the worst of both worlds.

Note that in this scenario you have returned the engine to essentially OE range rover spec and taken away TVR's upgrades to these engines.

You might get a higher peak torque value than than before, because as I understand it volumetric efficiency is higher at low revs (and declines with higher revs), meaning more energy from each bang - but at the cost of IMO removing everything that makes these cars what they are...


Edited by Dominic TVRetto on Thursday 6th July 14:56

Dominic TVRetto

1,375 posts

180 months

Thursday 6th July 2017
quotequote all
drlloyd said:
If you look closely at the standard Rover V8 EFI intake base you will see that two of the ports from each bank cross to the opposite side - making the intake base dual-plane. If you then divide the top section straight down the middle you will then make a dual plane intake manifold. It is seems as though Rover had this in mind all along but never followed through with this option.
We took advantage of this fact with our Lloyd Dual-Plane intake manifold. This greatly improves throttle response but the Rover V8 engine is far too cylinder head restricted for any intake modifications to make any significant difference to power output.
Kind regards, Daniel Lloyd
Yes, of course it does - doh!

I had completely overlooked that when I posted - please disregard my previous postings about not being dual plane, and my deepest apologies for my assertions that both your plenum and the Thor are not. As you say, the intake base takes care of that...

I stand by my comments on the Thor runner length being incompatible with TVR cams however - and the crossover runners on the intake base mean that it is difficult to get equal length intake runners, I guess this is where individual throttle bodies score an easy win...

drlloyd

145 posts

192 months

Thursday 6th July 2017
quotequote all
No problem. smile
Completely agree regarding runner length vs camshaft spec. The longer runner lengths of those intake manifolds are more suited to Land-Rover spec camshafts. We have actually seen Rover V8 engines making more power on 'lower' spec camshafts (i.e.: less overlap and less duration) with the same longer runner length intake manifolds. All tested on the same hub dyno.

RobXjcoupe

Original Poster:

3,151 posts

90 months

Friday 7th July 2017
quotequote all
drlloyd said:
No problem. smile
Completely agree regarding runner length vs camshaft spec. The longer runner lengths of those intake manifolds are more suited to Land-Rover spec camshafts. We have actually seen Rover V8 engines making more power on 'lower' spec camshafts (i.e.: less overlap and less duration) with the same longer runner length intake manifolds. All tested on the same hub dyno.
For arguments sake, a 4.0 engined chimera completely standard from the tvr factory, compared to a Thor manifolded 4.0 p38 Range Rover.
How do the torque figures compare?
I'm really interested that's all smile