Building a 10,000 rpm NA engine.

[Dessertrunner]

Harvey,
I think this is a good debate to have because the operation temp of the engine should be agree on if possiable. You and I may have to agree to disagree in the end but its worth trying to get some sort of understanding on this issue.

I accept for the best fuel economy the higher the burn temp the better.

For a race engine and getting the most power from the engine I don't agree.

The quick big of checking I did quickly indicate that exhaust gas temps are around 1,500F what we are debating is the difference between 140F and 180F whic is 2.6 % difference in the start temp to end temp. By reducing the engine temp the gains as I see it are, that we can get higher volume metric fill rate due to densor air and the engine will be less inclined to denotate.
As regards coating etc I haven't seen any mention of it in the articale we are talking about so I can't say if it has any effect.

Over to you to know convince me, I seem to remember you telling me the guys with the SC kits needed to get the engine temps down.

Tony

[icingdeath88]

Originally Posted by TomsSVX

Its there... out of the pump and into the y pipe

Tom

So then there is a bypass so the water can recirculate before the stat opens...?

[Dessertrunner]

Did some research seems there are some that so the hotter the better but by far the majority suggest cooler the better. Here is one of a number of articals. Will keep looking.
Tony

http://books.google.com.au/books?id=...rature&f=false

[SilverSpear]

Originally Posted by Dessertrunner

Did some research seems there are some that so the hotter the better but by far the majority suggest cooler the better. Here is one of a number of articals. Will keep looking.
Tony

http://books.google.com.au/books?id=...rature&f=false

I think that the issue of ideal temperature should be addressed according to engine. Germans for example love high temperature, and from our experience (20 years owning Mercs, around 14 cars and counting), the German engine takes 3x to get cooled when parked in comparison to both my Nissan and Subaru. Mercs run at 90~100*C. Our Jeep's ideal temperature is around 100*C or 210*F.

Following the hypothesis above, I assume the Japanese run at 80*C or less.
And since the EG33 is a 1.5xEJ22, it is logical to consult with the EJ experts and ask about the ideal operating temperature of these engines.

But I am inclined to agree with your link Tony. I think the EG33 will be happy at 80.

[SVXRide]

Originally Posted by bazza

As per my post here:

http://www.subaru-svx.net/forum/show...postcount=1339

This is all that is required. Each head already has a return, so we just add another one at the wax pellet to ensure the pellet is seeing real time flow and can open accordingly. Its actually nicer to do what Tony did and just add a little hole to the thermostat - less stuffing around etc. We can of course block the other return lines to the pump but considering the subaru turbos run a third return (and some svx) for the oil cooler I don't see a problem leaving them.

Also Bill you've got to remember that Tom and Dan have no real data - which means we're guessing.. Recall my eg33 did a heap of laps recently at Mallala and didn't blow up - based on your logic the engine must be fine and works. However the data shows oil surge in every single corner from lap one - oil pressure down to 10 psi. It was just luck it didn't fail. This is why we must ensure we have data proving the theories rather than just theories.



Tony that's good info about that v10.

Bazza,

You bring up a good point. There are many times in life that we don't realize how close we truly are to failure. Guess that's why we're always 3x redundant with everything we do at NASA, yet still have unforeseen failures.

Bill

[oab_au]

Originally Posted by Dessertrunner

Harvey,
I think this is a good debate to have because the operation temp of the engine should be agree on if possiable. You and I may have to agree to disagree in the end but its worth trying to get some sort of understanding on this issue.

I accept for the best fuel economy the higher the burn temp the better.

For a race engine and getting the most power from the engine I don't agree.

The quick big of checking I did quickly indicate that exhaust gas temps are around 1,500F what we are debating is the difference between 140F and 180F whic is 2.6 % difference in the start temp to end temp. By reducing the engine temp the gains as I see it are, that we can get higher volume metric fill rate due to densor air and the engine will be less inclined to denotate.
As regards coating etc I haven't seen any mention of it in the articale we are talking about so I can't say if it has any effect.

Over to you to know convince me, I seem to remember you telling me the guys with the SC kits needed to get the engine temps down.

Tony

I agree that it is worth discussing, as it is a very involved topic.
There are quite a few different temps in the engine that we are looking at, the water temp is just the end result, of the heat that is lost from the combustion. While we use water as the cooling medium, we are constricted by its low boiling point, oil or Air-cooled engines run at a higher temp for more efficiently and power.

The whole objective of the engine is to fill the cylinder with as much dense air as we can, then heat it as hot as we can, so that we get the highest expansion pressure, to push on the piston.

To this end we would do the best if we could get the gas temp of 1075*C to heat the air, but besides heating the air it also has to heat the piston, and the combustion chamber surfaces, that are running at 374*C. This reduces the amount of heat that we can get into the air, so our developed pressure is less, with a thermal efficiently of 36.45%

If we can maintain the temp of the piston and chamber at a much higher temp, we won’t waste as much heat. We can reduce the heat lost to the metal by using an insulating surface coating on all the metal in contact with the burning gas, the proportion of gas heat lost to the water will be less, and the heated air expansion pressure will be higher, for the engine to develop a higher torque.

So in our case the engine metal will need to be cooled, and as we are using water, we need to run the water temp as high as we can, while maintaining it in a liquid form.

The ultimate engine would be one that needed no cooling, with all the heat put into the gas, and the only loss being to the exhaust gas.


Looking at the temps, that the engine shows in Simulation at 6000rpm.
The mean gas temp is 1075*C.
The cylinder head temp is 374*C.
The piston temp is 374.4*C.
The cylinder liner temp is 211.4*C.

Harvey.

[Dessertrunner]

Hi Harvey,
So lets simplify the debate,
Do you agree that if the engine runs 2 hot at a given fuel and timing map if the temp of the engine goes up its more likly to cause denation?

[oab_au]

Originally Posted by Dessertrunner

Hi Harvey,
So lets simplify the debate,

I don’t think that is possibly Tony. To put it simply, the more heat used, to heat the air in the chamber, the more torque we will get.

Do you agree that if the engine runs 2 hot at a given fuel and timing map if the temp of the engine goes up its more likly to cause denation?

Well if you agree that you are running that engine outside its tuned parameters.
If the engine was tuned to operate at a particular temp, and it was getter hotter than it should, it will start to run outside its tune parameters, and detonation can occur.

Harvey.

[bazza]

In that article about the V8's - they only run the thermal coatings so they can run far leaner (hotter) during the races which means less kg wasted in fuel loads. In quallie they richen up (increase power and drop exhaust gas temps). Also in the F1 the other night one of the cars was running "lean / fuel saving mode" but was told to richen it up as the exhaust gas was to hot.

I think with our engines, cooler will be better as it looks after the exhaust valves, drops inlet temps (increasing power) and also allows more timing before detonation (more power again). 1 degree of timing in my turbo EG33 is about 25 bhp! Also our cars tend to run rather rich for their power compared to proper race cars. If we run a cooler engine jacket we can theoretically lean the engine out. We actually tend to run far to rich and you can lean out the fuel mixtures and gain a lot of power. For example mine is around 0.7 AFR with E85 - the V8's run about 0.88 AFR in quallie and 0.92 AFR in race (IIRC). If I leaned out from 0.7 to 0.85 I'd gain about 25-40 bhp!! The reason I can't is the risk of the possibility of the stock piston melting, however dropping the engine temp may allow it.

The only benefits of a hot engine seems to be economy and theoretically more power although many sources disagree on power.

[TomsSVX]

Originally Posted by icingdeath88

So then there is a bypass so the water can recirculate before the stat opens...?

Yes but not soley for this purpose... rememer i am tapping 2+ year old memories

Tom

[TomsSVX]

[IMG][/IMG]

You can see back r/s of y pipe i added the outlet for the heater core post powdercoat... hence paint run.

Tom

[Dessertrunner]

Originally Posted by oab_au

Why don't you ask me some thing hard.

If you are not looking at what the cam does to time the valves, then it is a pretty wide topic.


The Camshafts in our engine are unique, in that they can develop a harmonic resonate action that is increased with higher valve loads. When you look at how the valve load is applied to the shaft, it has a regular frequency that moves down the shaft, cylinder after cylinder, so that a harmonic frequency is developed, as each cylinder’s valves load the shaft in turn.



There is a lot of work on the lobes, to help the flow velocity at low speeds, while using higher lifts and valve timing that will increase the power at higher speeds. The inlet cam in the EZ30R is a good example.

Harvey.

Well Harvey lucky you mentioned the "harmonic issue" because it shed light on something we just found out. I spoke to Bazza last night he said that the EZ30R cams are set up so the two cam lobes for the values in each cyclinder are slightly out of time (I might have the wrong engine). This lead me to sctrach my head why,
I think its a couple of reason,
- First the two lobes out of time on each cyclinder means that the harmonics would be broken up. Would greatly reduce the issue.
- Reduce the load on the timing belt.
- Quite possiable that it enables more air into the cyclinder because it can squeze that last bit in. (not sure just guessing).

Opening to suggestions as to why you would do it.

Tony

[oab_au]

Originally Posted by Dessertrunner

Well Harvey lucky you mentioned the "harmonic issue" because it shed light on something we just found out. I spoke to Bazza last night he said that the EZ30R cams are set up so the two cam lobes for the values in each cyclinder are slightly out of time (I might have the wrong engine). This lead me to sctrach my head why,
I think its a couple of reason,
- First the two lobes out of time on each cyclinder means that the harmonics would be broken up. Would greatly reduce the issue.
- Reduce the load on the timing belt.
- Quite possiable that it enables more air into the cyclinder because it can squeze that last bit in. (not sure just guessing).

Opening to suggestions as to why you would do it.

Tony

I think the actually valve action for each cylinder would be the same, but the lobes for the two valves in the cylinder could be a few degrees out of phase.
This is done on some engines, to help direct the incoming gas flow, to one side of the cylinder so that it doesn't go straight out the exhaust valves on overlap.
This would not change the harmonic action on the shafts.

Harvey.

[bazza]

Originally Posted by Dessertrunner

Well Harvey lucky you mentioned the "harmonic issue" because it shed light on something we just found out. I spoke to Bazza last night he said that the EZ30R cams are set up so the two cam lobes for the values in each cyclinder are slightly out of time (I might have the wrong engine). This lead me to sctrach my head why,
I think its a couple of reason,
- First the two lobes out of time on each cyclinder means that the harmonics would be broken up. Would greatly reduce the issue.
- Reduce the load on the timing belt.
- Quite possiable that it enables more air into the cyclinder because it can squeze that last bit in. (not sure just guessing).

Opening to suggestions as to why you would do it.

Tony

Tony - check this: http://blog.perrinperformance.com/perrin-h6-build-up/

I found the information about the cam lobes on NASIOC - trying to find the link, it was posted by PDXTuning IIRC and included a heap of pictures of the cam lobe and head.

Also the EZ30R runs two timing chains - to reduce engine length.

[Dessertrunner]

Hi Harvey,
It would effect harmonics because you can't get harmonics on a randon effect. In other words a tuning fork repeats its action. Our cams repeat the pattern every 120degrees of the cam reveloution, therefor easy to create harmonics, if we gap those loads by even a couple of degrees we create 6 unequal loads/events, in other words long gap then short gap then long. Becomes a lot harder for the cam to create Harmonics.
Its the same as soldiders marching on a bridge have to break step, create a rand event.

I accept that it would be better for harmonic fix if the cam gap was larger but it will still reduce the point at which the shaft will break due to the harmonics.

Have a great day.
Tony