[LotusElise]

My memory on that is as sharp as a Ninja sword , s. https://www.k20a.org/forum/showpost.php?p=3126577&postcount=314

 

[M111]

Why did you not modify the pistons for more clearance or is the extra cam angle not needed anyway with this setup?

 

[LotusElise]

Why did you not modify the pistons for more clearance or is the extra cam angle not needed anyway with this setup?

I did ask Mahle about this, they don't release a further cutting of 1.0-1.2 mm in their pistons because of safety issues. A 50° capability would be great as significant torque increase comes with it. The DAMPFHAMMER engine is designed to love it, because it is an NA VE border riding engine design, but safety comes first.

 

[M111]

I'm surprised they sell a piston that is designed for performance builds that does not allow this, its not as if the A3 is a big cam.

Also very surprised you compromised on this as maximum VE over the widest range was the whole point of the build.

 

[LotusElise]

I'm surprised they sell a piston that is designed for performance builds that does not allow this, its not as if the A3 is a big cam.

Duration aren't the right measurement to rate the VTC, it's the centerline and the steepness of the valve lift gradient after the valve lash. Take a DC 3.2, which has roughly the same duration, but is likely able to run 6°-8° more.

Also very surprised you compromised on this as maximum VE over the widest range was the whole point of the build.

Stability of the piston crone and the combustion efficiency/duration. Also having bigger or higher edges beside the valve reliefs = more knock. All calculations and simulations are done on the actual capability of VTC. It's still ok .

 

[t3gav]

Looking good! Have you got a complete list of engine mods so I can have a guess? ; )

 

[LotusElise]

Looking good! Have you got a complete list of engine mods so I can have a guess? ; )

You can make guess out of competition as the guessing game had unfortionally a deadline for guesses. Out of the competition you can do a guess.

The List:
CAI, IM, Port, H and CATback reflect the DAMPFHAMMER concept, I did develope, and are prototyed. The concept included also standard aftermarket parts for load control, CR increase, valve timing and loudness control.

 

[Scider]

So it were ITB's with an EFI system they use there?

Hopefully this link works:
https://photos.app.goo.gl/rk97RR4rRMVKC4i1A

If not, let me know! This is a set of ITBs for the GM Indycar circa 2002. The big hole in the side was actually where an injector block would get bolted in and would direct fuel flow into the left and right ports as well as up the velocity stack. One injector was used on the top of the injector block. It didn't have a spray pattern, more like a laser to shoot liquid methanol into the cylinders. At an AFR of 4:1 if the fuel didn't evaporate it would be enough to hydro-lock the engine

 

[LotusElise]

This is a set of ITBs for the GM Indycar circa 2002. The big hole in the side was actually where an injector block would get bolted in and would direct fuel flow into the left and right ports as well as up the velocity stack. One injector was used on the top of the injector block. It didn't have a spray pattern, more like a laser to shoot liquid methanol into the cylinders. At an AFR of 4:1 if the fuel didn't evaporate it would be enough to hydro-lock the engine

Thanks for the pictures Scider! I read about the approaches in a SAE paper about using non-spreading-spray pattern to increase the VE and the cooling capacity. But for this you need fuel with a low evaporation temperature and low specific heat capacity to get it properly mixed in the chamber. Alcohols and other stuff like Hydrazin are perfect partners for this approach. I run pump fuel, so I have to go a bit a different route for the best compromise on those two counter fighting parameters.

Otherwise, I know a colleague, who did some combustion analysis for one of the four big OEM's here in Germany with high pressure port injection to follow a similar route like the Indy-race engines. We talked about this for my project, but I would need for this a special driver to run the injectors. I also didn't like it because my aim is to reach my goal with as most standard parts as possible for the essential systems and to introduce innovations there where aftermarket is typically innovating.

To the hydro-lock issue. I know from Drag Engines, who run on Hydrazin or Nitro-Methan fuel which are really near to hydro-lock to get the fuel in for boosted applications. Top fuel dragsters are filled up their OT chamber volumes with almost 50 % Nitro-Methan because of the very low AFR of 1.28:1 down to 1.00:1 they run at WOT (AFR stoich. = 1.7:1), the pretty high CR and impressive boost levels of 60+ psi.

BTW, a 4:1 AFR would be around a lambda of 0.6, this need to be a very fast and hot flame front not to get extinguished by the liquid fuel in the chamber. What fuels are allowed in the Indy-Car Series?

 

[LotusElise]

Also very surprised you compromised on this as maximum VE over the widest range was the whole point of the build.

For your interest, Lotus told me the CP pistons with extra deep valve pockets feature have 3 mm PtV clearance on his 93 mm stroke engine. If the piston deck height is the same, it should also apply to the 86 mm stroke engine. But these pistons are low silicone content Alu alloy's, not like the 4032 alloy of Mahle, having a lower thermal expansion coefficient. Maybe Lotus can chime in and report about the eventual noise he can here at lower loads with the CP's?

 

[Lotus]

Markus, my pistons are from supertech, not CP.
They are mode from a 4032 type of alloy. I once even heard the forging slugs are supplied by Mahle, but I am not sure.
I run a nominal 80µm piston to bore clearance with them and have no hearable noise during cold operation.
Nominal as the centre of the bore has closer to 100µm cold clearance.
The reason is that during honing (with a honing brace) focus was on roundness, not absolute diameter. Rings seal better in round bores.
In the middle, it took a tad more to get them round.

 

[LotusElise]

Markus, my pistons are from supertech, not CP.
They are mode from a 4032 type of alloy. I once even heard the forging slugs are supplied by Mahle, but I am not sure.

Oh sorry for wrong remembering. Concerning the technology transfer Supertech states on their website: "Supertech pistons are manufactured in Argentina with technology transferred from European manufacturers.". Who know what it include.

I run a nominal 80µm piston to bore clearance with them and have no hearable noise during cold operation.
Nominal as the centre of the bore has closer to 100µm cold clearance.
The reason is that during honing (with a honing brace) focus was on roundness, not absolute diameter. Rings seal better in round bores.
In the middle, it took a tad more to get them round.

I run a similar piston to bore clearance with my 4032 alloy Mahle piston too. Good to know they don't slack around .

 

[LotusElise]

Update

Fluid systems:
Fuel system is almost finished now. We just have to add the fuel pressure sensor. The coolant system made a huge step forward because the big circuit piping is finished.

The coolant-oil-flow concept:



The big circuit coolant piping:



First check of interface clearance:



Shows my welder is a Genius at work! You can see the piping coming down from the oil-coolant-cooler and get connected to the 2-path thermostat left-hand and to the big circuit piping on the right-hand side, like the concept shows. The pump will get attached to the short circuit.

The thermostat get flowed in closed position from engine to pump and in open position from front cooler to pump. It opens at around 82 °C and is fully open at around 96 °C. The ECT closed loop control will keep the temperature at around 88 °C, there where the thermostat flow is in a "near to linear" flow to lift behavior for easier control and depress oscillation of the ECT between these two control circuits. I am really curious if the will gonna work as intended as there are many open questions left whose answers I did assume...not the best engineering method, but still a method . I hope the inaccuracy in my assumptions can be compensated by the boost control function tuning (= ECT control tuning). The mapping is so flexible, it should work for even biggest failures in them.

 

[LotusElise]

Fluid system:
Upgraded the pump an the cooler to CWA400 and ECD54-182 because of specification and safety reasons. Some reports about the C43-182 use for racing and the still guessed oil flow flux of the K20A2 oil pump over pressure made me deciding for it. That means doubling flow and pressure capability of the pump, doubling of rated heat flux from oil to cooler and less than half of pressure drops on oil and water side. It was an expensive decision, but better than replacing it later. An indication for oil flux I found a few days ago on K20a.org, stating it is according the RSX manual 54 l/[email protected] rpm...maybe flow without pressure.

Electric system:
Sensors sent to welder. The E-technician is briefed and have all the sensor harness informations (flow schematics, sensor list, control functions, ...) he need. Need to get an arrangement of the mechanic stuff finish due date to start the harness stuff.

 

[t3gav]

Fluid system:
Upgraded the pump an the cooler to CWA400 and ECD54-182 because of specification and safety reasons. Some reports about the C43-182 use for racing and the still guessed oil flow flux of the K20A2 oil pump over pressure made me deciding for it. That means doubling flow and pressure capability of the pump, doubling of rated heat flux from oil to cooler and less than half of pressure drops on oil and water side. It was an expensive decision, but better than replacing it later. An indication for oil flux I found a few days ago on K20a.org, stating it is according the RSX manual 54 l/[email protected] rpm...maybe flow without pressure.

Electric system:
Sensors sent to welder. The E-technician is briefed and have all the sensor harness informations (flow schematics, sensor list, control functions, ...) he need. Need to get an arrangement of the mechanic stuff finish due date to start the harness stuff.

I saw your post on FB, hard to believe it will only decrease oil temps by 3 deg, be good to see some actual results on the setup, maybe join the oil lines together and do a before and after

 

[LotusElise]

I saw your post on FB, hard to believe it will only decrease oil temps by 3 deg, be good to see some actual results on the setup, maybe join the oil lines together and do a before and after

Sure I will test it t3gav . What I've shown there is following setup:

• oil volume flux = 40 l/min ->
• Oil inlet into cooler = 120 °C
• Coolant inlet into cooler = 85 °C
• coolant volume flux = 120 l/min

If you take those values for the Oil outlet of cooler temperature check of the C43-182 data, then your finger will point on spot at 117 °C, which is a tiny decrease of 3 °C.



If this result doesn't fit real life experience the oil volume flux would be lower in reality and the RSX manual value of 54 l/[email protected] rpm is at zero pressure. If the pump sees more pressure at the outlet, the flow rate decreases of course. Finally the flow rate is a function of the system back pressure over the flow rate map. This makes first order assumption challenging as oil flow rate as well as the back pressure of the oil circuit is unknown and just can be based on assumptions.

Edit: the diagrams are based on exact those temperatures according laminova which I took.

 

[LotusElise]

I have to add, the needed flow rate of coolant at peak power is almost 155 l/min, just to cool the engine heat away. This value considers the percentage values radiated, convected and unburned heat based on measured values of a typical gasoline I4 engine. Nice to know, almost 10 % of the wasted heat is bounded into unburned fuel at a operation point at the lean side of a lambda of 0.92. In total 742 kW are wasted while just 224 kW are seen at the flywheel at this point, laughable, but the K-series engines are on the better side. If you consider a Subaru EJ275, which is one of the worst ones, the ratio of utilized power and waste is around 26-28 %. One of the best ones of its time, the GM (Opel) C20XE (best point 38 %) is around 33 % at WOT.

Nice to know, my engine will produce around 1000 hp, just at the wrong output :devil:.

 

[Lotus]

Markus,
beyond some 2000 or 3000 rpm oil pressure is limited by the spring. Excess flow is returned to the pump inlet. I can nicely see this on my pressure gauge.
I run a 1.5mm shim on the pump valve spring and see 5.4 bar max. oil pressure.
They 54 l/min may be what the pump pumps, but not what is actually flowing through the engine.

 

[LotusElise]

...They 54 l/min may be what the pump pumps, but not what is actually flowing through the engine.

Thanks Lotus. From the available data, I also get the impression of it is just the back pressure less volume flux. Maybe stated in the manual for test reasons, filling up cans to check the flow rate.

 

[Lotus]

OK, Fiat Tipo engine and cold oil, but at 2000 rpm they measured an oil flow on the order of 5 l/min.

http://mtmcongress.com/proceedngs/2016/Summer/3/08.THE INFLUENCE OF LUBRICATION OILS AND FILTERS ON THE OILS PRESSURE, TEMPERATURES AND FLOW DURING ENGINE WARM-UP AT SUMMER CONDITION.pdf

Fully warmed up 1.5l inline 4 turbodiesel: at 3 bar they saw 10 l/min total oil flow with half of that coming from the piston cooling oil jets.

http://eprints.nottingham.ac.uk/36081/1/2016-01-1045.pdf

Iveco 3l inline 4 150-210HP 350-470 Nm turbodiesel: 10-30 l/min measured actual oil flow though engine
https://www.mdpi.com/1996-1073/11/1/10/htm




These oil pumps are overdimensioned a lot just like mechanical water pumps as they have to provide proper lubrication even at very low rpm. All the excess is returned through a pressure relieve recirculation valve in the oil pump housing.

I believe this number of 54 l/min, but this is total flow at zero back pressure, i.e. no recirculation flow. The flow though the engine is way smaller.

There are now developments of electric oil pumps to curb the unnecessary power zapped by too fast spinning oil pumps.

I would say you won‘t be too far off calculating with 10-15 l/min.

If one has a spare block, you could actually force feed it with a low viscosity oil (to simulate hot oil) pressurized at 5 bar and measure actual flow.