Thread: things to upgrade for high performance

Back in the 80's most all Japanese diesel manufacturers had cam wear problems and the quick 'fix' was to specify a high 3000+ppm calcium level in the engine oil additive package (and to ban API CG-4 oils from use)

Modern spec mid and low ash oils seem to work fine, even though they have lower calcium levels than was specified at the time as the EP package has been boosted with other compounds.

I tend to think it was a heat treatment/metallurgy problem as it was common to a lot of Japanese diesels at the time and coincided with the introduction of the API CG-4 spec which reduced certain additive levels in the oil.
This was addressed with the API CH-4 spec, but the deed was done and thereafter all the Japanese manufacturers specified CF/CF-4 oils only.

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

I have currently stripped my motor down so it's now "naked" just tidying things up so that it's all properly done.
Whilst doing this I have decided I would like to make a custom exhaust manifold which I then got a piece of plate machined the surfaces and drilled the holes for the studs and am now trying to figure out what I am going to do about having rectangular port holes and making the manifold out of round tube what's the best way I don't know ... the size of tube that covers the rectangular holes I believe will be too large and cause problems maybe due to velocity decreasing due to the larger diameter tube ???

I have also taken off the intake manifold and am trying to figure out what I will do about the water/methanol injection and am thinking the following:

1.I am going to run a pressure switch that will operate once close to max boost pressure.

2.i was considering a nozzle in each runner tube but then wondered what about for that small moment when the intake valve is closed but the water is still being injected i imagine a small amount will accumulate and once valve re-opens it will suck in a minuscule amount but be enough to cause some problems???

3.am I just to put 1 nozzle at the entry to the manifold and let it do it's own thing from then on ?

For my custom exhaust manifold (not finished - had to go down the list):

Sorry I can't remember all measurements and it is in storage a long way from my current location.

I used 12mm thick plate for the head side and turbo flanges and 40 NB (nominal bore) butt-weld elbows, etc. for the rest. From memory I think I chose std weight wall thickness for the 40 NB fittings - the cross section area inside was well suited.

For the head flange a hole was drilled through at each of the 4 port locations. From memory the diameter of the hole matched the width of the port in the head (width is much smaller than height and less than inside of piper fittings).

On the opposite side to the head the flange was machined to match the weld preparation chamfer on the butt-weld elbows, about 1 mm deep only.

Then time consuming work to blend the transition from the rectangular exhaust port in the head to the circular inside diameter of the 40 NB fittings. This transition converges from the top and bottom of the exhaust port and diverges from the sides of the port. The transition angles would be better if the flange was thicker, but I used material that was on hand.

Thanks again John !!
I did not get time to do any cross sectional measurements of the ports or of the tube I have on hand but I'm assuming 40NB is roughly the same area as the ports.
I can foresee the biggest struggle being keeping the runners as short as possible and fitting it in the space provided.
I would love to see your design but I'm guessing it's still down here in nsw close to my location and your up there?

What did you use to go into the turbo flange end ? 4-1 collector ?

Thanks Rick I heard something about that but now you explained it it's all clear now! I'm not to familiar with oil specs but I have found delo400 was good and am now using rimulaX and it seems good.

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

[snip]

What did you use to go into the turbo flange end ? 4-1 collector ?

The collector is critical, IMO you want to minimise sectional area changes and so need a merge collector to maintain velocity.

You can make your own (a PITA, I've done it for NA engines) and probably the only way you'll get one with heavy walls or buy one (probably $$$$, or at least they used to be but it looks like every man and his dog is making them these days)

Yeah if it was thin walled stuff it would be easier but being thick walled I've got some more trouble I recon. You wouldn't have any photos or anything would you ? I would like to see Randy's design but I cannot find any pics unfortunately. I am aiming at keeping the runners as short as possible , thick wall to retain heat , as even length as possible and separated for as long as possible as you would already know.

I'm also wondering is there any significant gains to be made by making a custom manifold on our setups ?Would it be noticeable in spool up time ?

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

Thanks again John !!
I did not get time to do any cross sectional measurements of the ports or of the tube I have on hand but I'm assuming 40NB is roughly the same area as the ports.
I can foresee the biggest struggle being keeping the runners as short as possible and fitting it in the space provided.
I would love to see your design but I'm guessing it's still down here in nsw close to my location and your up there?

What did you use to go into the turbo flange end ? 4-1 collector ?

I haven't got that far, but wanted to try and use the following pulse convertor design - to save typing the following quote is a post of mine from a different forum:

Turbo exhaust manifolds can be pulse, constant pressure, or pulse converter systems.

Pulse and pulse converter systems try to use the higher available energy (relative to a constant pressure manifold) when the exhaust valve opens.

Pulse systems have no more than 3 cylinders per turbine inlet.

Pulse converter systems are used for 4, 8 and 16 cylinder engines because pulse systems are difficult with these numbers of cylinders.

One pulse converter is required for a 4 cylinder engine. 2 converters for an 8 cyl engines, and 4 converters for 16 cyls. There would be one turbine entry at each converter.

They were developed to produce steadier and more efficient flow at the turbine than pulse systems. Turbine efficiency is improved at the expense of some performance at low speeds and loads.

By using a pulse converter to connect 4 cylinders to a single turbine inlet, the low efficiency period between exhaust pulses of a 2 cylinder per turbine inlet pulse system is overcome.

The critical parts of the pulse converter are the nozzles that accelerate the gas as it enters the junction at the turbine inlet. This minimises pressure pulse transmission from one branch to the other branch, avoiding a pulse from one cylinder adversely affecting the scavenge process of another.

In its simplest form (using the 4BD1-T firing order), No's 1 and 4 ports are connected, as are No's 2 and 3, which then merge at a pulse converter at the turbine inlet.

Alternatively multiple entry pulse converters (patented), can be used with 3 or 4 manifold branches joining in the pulse converter at a single entry turbine.

The following diagrams were taken from the Diesel Engine Reference Book. The recommendations for the pulse converter include:
- cross section area of pipe should be 0.5 to 1.0 x area of turbine throat
- cross section area of nozzle should be 0.65 to 0.85 x area of pipe

Edit: The graph is from an 8 cyl engine, comparing a pulse system (left) to pulse converter system (right).

The continuous line with large peaks is the pressure pulse in exhaust branch of No 1 cylinder as the crank angle changes.

The short dashed line is pressure at the turbine inlet. Note that with the pulse system it closely follows the pressure in the exhaust branch and has high peaks and low dips. It is more uniform with the pulse converter.

The long dashed (difficult to distinguish) line is the boost pressure. About 2.3 bar for the pulse system and about 2.5 bar for the pulse converter system.

The heavy bars along the bottom are inlet and exhaust valve periods for No 1 cyl.