Thread: things to upgrade for high performance

Can I stop saying thanks John and you just automatically assume I have said it ???
I was looking at a few other documents and found similar findings as you just posted with the 2-1 pulse converter it is an interesting idea that in theory should give some beneficial gains.. I can foresee a lot of work trying to replicate Randy's design as he seems quite clever with his hands but I could give it a go.. I may need to minimize the thickness of the head side flange as I am using 18mm plate opposed to your 12mm I done this worried about it warping under extreme heat but now looking at it it's overkill ....
I would like to see how randy made his transition from the port hole shape to the circular tube wether he done what you have done as previously stated or tyred something different...
Reason for me thinking about starting this mod is that even though it has been suggested that the factory turbo manifold is probably the best off the shelf construction I looked at it and seen that No*1. and No*4 cyls do have an abrupt and quite close 90* which also abruptly cuts off No*2&3 cyls.

John, I wonder if anyone has done any comparative testing of a pulse system vs a merge collector ?

mmm would be interesting to see what the difference is and then compare them to the log manifold.
only part about the converter one that you suggest john is the part where you said about low end is effected as i am looking for as much low end as possible. then again i may have misunderstood your statements?

Originally Posted by rick130

John, I wonder if anyone has done any comparative testing of a pulse system vs a merge collector ?

Sorry I don't know. Most of the work on pulse converters that I am aware of including the info I included above seems to have been done by manufactures of diesel engines used to power ships - they can realise large gains and justify developement.

IMHO the valve timing used in the pre 1989 4BD1/T would lead to greater gains from the use of a pulse converter system - the exhaust valve opens earlier and closes later compared to later engines.

Originally Posted by c.h.i.e.f

mmm would be interesting to see what the difference is and then compare them to the log manifold.
only part about the converter one that you suggest john is the part where you said about low end is effected as i am looking for as much low end as possible. then again i may have misunderstood your statements?

Where did I say that?

I think the pulse converter might even improve low end as the exhaust valve overlap between the cylinder where the valve has just opened before BDC (which provides the high pressure pulse) and the cylinder that fired before it and still it's valve open (where the pressure is lost) covers a longer time.

Originally Posted by Bush65

Sorry I don't know. Most of the work on pulse converters that I am aware of including the info I included above seems to have been done by manufactures of diesel engines used to power ships - they can realise large gains and justify developement.

IMHO the valve timing used in the pre 1989 4BD1/T would lead to greater gains from the use of a pulse converter system - the exhaust valve opens earlier and closes later compared to later engines.

When I get the time I plan to run a CFD simulation of the OE 4BD1T manifold - thanks to Dougal who drew up the geometry. It would be relatively easy to simulate a few manifold options at the same time.

John (and others) - care to suggest the most suitable boundary conditions?

Originally Posted by isuzurover

When I get the time I plan to run a CFD simulation of the OE 4BD1T manifold - thanks to Dougal who drew up the geometry. It would be relatively easy to simulate a few manifold options at the same time.

John (and others) - care to suggest the most suitable boundary conditions?

Sorry I can't add much help re boundary conditions.

Just out of interest what CFD package do you plan to use?

One of the better engine analysis I remember seeing used Ansys MultiPhysics - they modelled the entire engine including fuel injection and combustion. I used this many years ago (ver. 5 from memory), never had occasion to use the CFD part of it, but it seemed quite good (can't remember the name of the CFD part of it - too many sleeps since).

Originally Posted by Bush65

Sorry I can't add much help re boundary conditions.

Just out of interest what CFD package do you plan to use?

One of the better engine analysis I remember seeing used Ansys MultiPhysics - they modelled the entire engine including fuel injection and combustion. I used this many years ago (ver. 5 from memory), never had occasion to use the CFD part of it, but it seemed quite good (can't remember the name of the CFD part of it - too many sleeps since).

We use OpenFOAM. It is free (open source) and is rapidly taking over from ANSYS/FLUENT.

[ame=http://www.youtube.com/watch?v=T9WafiQFEpA]Engine Ignition Simulation with OpenFOAM - YouTube[/ame]

OpenFOAM for Internal Combustion Engine Simulations, Combustion and Spray - Ofwiki

The best part is that we have a 9000 core computer to run it on. No company in the world can afford 9000 Ansys licences.

By Boundary conditions I was mainly looking for your best guess for a suitable (pulse) flow rate, frequency, pressure, temperature etc... At the exhaust ports. We can of course calculate it from (assumed) VE, cam timing, assumed stoichiometry etc... However I thought it may save time if you had a rough idea of the numbers already.