Independent runner inlet manifold

Independent runner inlet manifold

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RobXjcoupe

Original Poster:

3,151 posts

90 months

Thursday 13th July 2017
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Ok so no one has comparable torque figures.
That seems a bit strange as there is a lot of figures going around after modification.
Below are a couple of interesting pictures of a modified 3.9.
Claimed figures are 250bhp with 270ftlb of torque. Not sure where in the rev range though. Looks like a version of a Thor manifold.


Dominic TVRetto

1,375 posts

180 months

Sunday 16th July 2017
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Surely that's a set of throttle bodies mounted on a John Eale's crossover manifold?

That's the set-up I would have if going further down the NA route - unfortunately works out petty much the same cost as a turbo kit, so you have to question whether you want less power but better response vs big power...

Boosted LS1

21,165 posts

259 months

Sunday 16th July 2017
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Turbo's can be very responsive especially if the stock compression is maintained.

RobXjcoupe

Original Poster:

3,151 posts

90 months

Monday 17th July 2017
quotequote all
Boosted LS1 said:
Turbo's can be very responsive especially if the stock compression is maintained.
Under bonnet temps are high anyway without an additional heat source. I'm not one to cut out cooling vents and holes although I'm sure a turbo conversion is extremely good.
I'm ok with n/a power but I'm looking at this dual plane inlet conversion and it seems all I've found don't cross over the middle four inlets to Eliminate charge-robbing between consecutive firing cylinders. Without obviously changing the firing order, a middle crossover inlet would give a LRLRLRLR induction order.

Dominic TVRetto

1,375 posts

180 months

Monday 17th July 2017
quotequote all
From what I understand, if you are looking at designing an intake system (dual plane or not), there are a number of considerations to maximise the volumetric efficiency within the cylinders and increase the torque.

Ignoring cylinder firing order, some of the considerations include (in no particular order)..:

1. Plenum volume
2. Plenum shape (minimise turbulence, pressure wave tuning, etc)
3. manifold runner length (tuned to rpm you wish to maximise torque at)
4. manifold runner cross-sec. area (corresponding to flow at rpm you wish to maximise torque at)
5. manifold runner shape (packaging & necessity vs. least restriction to flow, minimising fuel dropout etc)
6. Distance between inlet tract opening & plenum "roof" (tuning helmholtz resonance at rpm you wish to maximise torque at)

There are loads of factors I will not have touched upon, as this is an extremely complex area which I know very little about but find extremely interesting.

Something I found useful as an intro - and comparatively brief - was this pdf here.

I cannot comment on it's scientific exactness, but it will give you an intro into the concepts and terminology involved in this area...

HTH,


Dom

RobXjcoupe

Original Poster:

3,151 posts

90 months

Monday 17th July 2017
quotequote all
Dominic TVRetto said:
From what I understand, if you are looking at designing an intake system (dual plane or not), there are a number of considerations to maximise the volumetric efficiency within the cylinders and increase the torque.

Ignoring cylinder firing order, some of the considerations include (in no particular order)..:

1. Plenum volume
2. Plenum shape (minimise turbulence, pressure wave tuning, etc)
3. manifold runner length (tuned to rpm you wish to maximise torque at)
4. manifold runner cross-sec. area (corresponding to flow at rpm you wish to maximise torque at)
5. manifold runner shape (packaging & necessity vs. least restriction to flow, minimising fuel dropout etc)
6. Distance between inlet tract opening & plenum "roof" (tuning helmholtz resonance at rpm you wish to maximise torque at)

There are loads of factors I will not have touched upon, as this is an extremely complex area which I know very little about but find extremely interesting.

Something I found useful as an intro - and comparatively brief - was this pdf here.

I cannot comment on it's scientific exactness, but it will give you an intro into the concepts and terminology involved in this area...

HTH,


Dom
It's very interesting to read. I've got some good ideas of which are explained and it gives me more ideas smile
The hard part is getting the middle four inlets crossed over and maintaining the minimum factory internal diameter of those runners. I have a good idea how to do that and it doesn't use conventional pipework which keeps the height down to fit under a standard bonnet which is a huge hurdle to start with wink

Dominic TVRetto

1,375 posts

180 months

Tuesday 18th July 2017
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The other issue is that cross over runners will be longer than the others, if you go in a straight line - hence the others would have to be artificially lengthened through curving in order to be of equal length (think of the single "coiled" header in an equal-length manifold for a 4-pot)...

These curled ones would then have different flow characteristics to the cross-over ones, due to the effects of bends on gas flow, etc etc

This is why in some ways the individual throttle bodies solution is preferable - it completely eliminates the need for crossover runners etc, and delivers the most effective solution for the effects you are seeking, in the most simple package... At a price.

And is not for track cars only - so many performance cars have them from E46 M3 and Speed 6 TVR's upwards, due to the benefits they bring.

I'm all for dual plenum as a cost effective solution - is just a pain to have to do all the development work yourself (where the failure rate may render it not cost-effective), when there are off-the-shelf alternatives on offer...

But with time and a workshop on hand I wish you all the best and will continue reading with interest smile

Edited by Dominic TVRetto on Tuesday 18th July 13:30

RobXjcoupe

Original Poster:

3,151 posts

90 months

Tuesday 18th July 2017
quotequote all
I understand, i think it's a matter of not making the dual plenum a regular shape and possibly using baffles inside to correct any volume issues. I can make these adjustable to a degree, to give longer or shorter runner length and also create a Venturi to increase air flow and reduce air pressure if I can't get a specific runner length under the bonnet. I'm a long way off at the moment though.
My biggest headache is getting the electronic side of things working. That I really haven't a clue but I suppose that's a future different thread smile

drlloyd

145 posts

192 months

Tuesday 18th July 2017
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RobXjcoupe said:
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
Hello Rob. Sorry for the late response, don't get on here often.
We have never had a Thor manifolded 4-litre P38 on the dyno and it is difficult to accurately compare a rear-wheel drive manual transmission to a 4WD auto transmission - due to the differences in transmission losses and the subsequent errors in estimating those losses. The only way to accurately work out the answer to your question is with an engine dyno and really you need to take out any other variables as well - e.g.: difference in camshaft profile, compression ratio, etc.

If you ever want a significantly more prompt response, contact me through my work e-mail! smile

RobXjcoupe

Original Poster:

3,151 posts

90 months

Tuesday 18th July 2017
quotequote all
drlloyd said:
RobXjcoupe said:
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
Hello Rob. Sorry for the late response, don't get on here often.
We have never had a Thor manifolded 4-litre P38 on the dyno and it is difficult to accurately compare a rear-wheel drive manual transmission to a 4WD auto transmission - due to the differences in transmission losses and the subsequent errors in estimating those losses. The only way to accurately work out the answer to your question is with an engine dyno and really you need to take out any other variables as well - e.g.: difference in camshaft profile, compression ratio, etc.

If you ever want a significantly more prompt response, contact me through my work e-mail! smile
No probs and thank you smile