intake manifold modification

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Originally Posted by OldMav

Sadly these guys and I will not write there name but its only a STD manifold made pretty. these guys missed the boat and the opportunity to do something special. I haven't flow benched this manifold but I already know from experience it is marginal and as pressure rises it will get less results than the Bog STD manifold due to the absolutely silly radiuses on all edges. Even the Nissan engineers knew this and made there radius 15mm radius minimum.. Also $1500 for a pretty looking no better than a STD manifold is a joke.

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presume this is to do with ebays pic of manifold .
agree $1500 lol.

more radius adds turbulence if air is introduced centrally?

Now I'm a little confused,
gtr's plenum round, in all 3 dimensions.

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Originally Posted by OldMav

The 4 inch does do a bit. I actually fitted a 5 inch on the manifold lol it did give a increase on the dyno Kw and Nm. Which gave me the motivation to do the current cooler manifold system.

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Ok, I wouldnt be able to fit a 5 inch pipe to my manifold.... is it better to be round?

Would I be right in saying that the first major goal of manifold design should be equal flow to all cyclinders? Then chase better allround figures?

Maybe off topic a bit, but with an intake system is there a boundry layer of air and what affect can that have on design?

Cheers
Benny

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Originally Posted by Robo

presume this is to do with ebays pic of manifold .
agree $1500 lol.

more radius adds turbulence if air is introduced centrally?

Now I'm a little confused,
gtr's plenum round, in all 3 dimensions.

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Robo Yes the comments are towards the ebay pic manifold only. For runner entry or divider edges there can be no sharp edges above 15mm radius edges give diminishing returns but under 15mm radius entry edges to the runner create vortex turbulence at those edges which extend into the runner causing choke or less area for fast accelerating air to pass in other words makes the runner entry smaller as air accelerating air. This manifold has no more than 5mm radius edges. For our diesel plenum lid it a accumulator not a plenum as such so the lid top makes no difference for top entry position, But for front entry systems then at least the radius of the entry tube does have a minimal improving effect.

Quote:

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Originally Posted by OldMav

Robo Yes the comments are towards the ebay pic manifold only. For runner entry or divider edges there can be no sharp edges above 15mm radius edges give diminishing returns but under 15mm radius entry edges to the runner create vortex turbulence at those edges which extend into the runner causing choke or less area for fast accelerating air to pass in other words makes the runner entry smaller as air accelerating air. This manifold has no more than 5mm radius edges. For our diesel plenum lid it a accumulator not a plenum as such so the lid top makes no difference for top entry position, But for front entry systems then at least the radius of the entry tube does have a minimal improving effect.

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G'day Peter,

I am now going down the chev V8 diesel path. I wonder if you have had much to do with those engines, if so, do they also suffer from intake manifold problems as well?

I have just sent the following e-mail to Jim from Baylock.

"G’day Jim,

The last time I wrote to you I was seeking advice regarding your switchblade turbo set-up to suit a Nissan Patrol 4.2 turbo diesel engine.

However, things have now changed, I am currently in the market place to purchase a Nissan Patrol with a Chev 6.5 turbo intercooled diesel engine conversion.

Question: Jim do you provide a switchblade turbo set-up to fit this type of engine?

If yes, what would be the cost mate?"

I will keep both you and nissannewby informed of my progress.

Regards,

RLI

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Originally Posted by Ben-e-boy

Ok, I wouldnt be able to fit a 5 inch pipe to my manifold.... is it better to be round?

Would I be right in saying that the first major goal of manifold design should be equal flow to all cyclinders? Then chase better allround figures?

Maybe off topic a bit, but with an intake system is there a boundry layer of air and what affect can that have on design?

Cheers
Benny

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Benny Your manifold is a very nice manifold and addresses the distribution component very well but the issue here is not the manifold its the air speed changes that happen when air has to change its acceleration speed so many times. For example high speed air entering the cooler then abruptly slows down to be cooled then has to speed up again to exit the cooler then slow down again as it enters the plenum. The cooler to plenum caused a backup effect when you are trying to go from high boost to low boost situations, due to the shortness of the system unlike a front mount this in my experience helps to causes surge. Even just a 4 inch pipe there does reduce this effect allowing the plenum and cooler volume to reduce this effect as a accumulator. Hence my cooler to plenum connection system. This is only my experience for fast spooling high volume turbo's like the 3071 type.

Hi Paul
Yes mate I have looked at the 6.5 Chev..I have actually rebuilt one only and driven a number on long trips and in play. I am going to try to be positive here and that is really really difficult to do when you are looking at 1940's diesel design. But if you like lazy power with very short revs connected to a manual Nissan gearbox not suited to its short torque curve then they are a great engine as there is no replacement for displacement. But I will warn you this engine is not designed with strength as a paramount virtue. The head has odd smallish runners with odd curves and a manifold that is designed around petrol design and vacuum. But they do react to a turbo quite well but you have a limit as to how much air volume you can pump into the combustion chamber, As pressure doesn't automatically mean volume.

To answer your question that's a yes they do have intake induction system issues, but fixing them is difficult to do with centre V induction.

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Originally Posted by RLI

G'evening Lounge Lizards,

Due to me selling my 4.2 turbo diesel GU wagon, as previously advised, i am currently putting my Patrol back to stock. Therefore, i will be taking off the UFI inlet manifold built by Matt Craig in WA, which is designed to fit to the Cross Country intercooler set-up.

PS, i will keep you posted when i offer it up for sale.

Regards,

RLI

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Gday mate,sent you a pm,not sure if you got it though??

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Originally Posted by tassie wombat

Gday mate,sent you a pm,not sure if you got it though??

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G'day mate,

I received your PM, I will contact you soon.

PS, i am a lazy bastard at times. lol

Regards,

Paul

No worries mate,cheers.

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Originally Posted by OldMav

Robo Yes the comments are towards the ebay pic manifold only. For runner entry or divider edges there can be no sharp edges above 15mm radius edges give diminishing returns but under 15mm radius entry edges to the runner create vortex turbulence at those edges which extend into the runner causing choke or less area for fast accelerating air to pass in other words makes the runner entry smaller as air accelerating air. This manifold has no more than 5mm radius edges. For our diesel plenum lid it a accumulator not a plenum as such so the lid top makes no difference for top entry position, But for front entry systems then at least the radius of the entry tube does have a minimal improving effect.

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Think I'm reading you, given the preferred radius and---
so adding volume/space by raising the top by 50mm gives the air flowing inwards room to become less turbulent and thus allows for a larger air volume to enter & flow though the runners.
and at the same time keeping inlet manifold size optimal to not suffer pressure drop.