Big Issues with Cylinder Pressure (DCR)

[plovett]

Continuing on the topic of CAI and ambient temps, part of this build was ceramic coating the headers and intake man. Any thoughts on if this will actually do anything to reduce temps in the engine bay?

I think ceramic coating of headers can make a big difference. I am not so sure about the intake manifold.

paulie

[David Redszus]

I can appreciate every point in this reply.
For me personally, it's about incorporating "the stuff I have laying around" AND mixing it up with the current and more advanced thinking. This thread alone, which has contributions from the usual suspects, has shed some light on possible places where I might make progress while still immersed in the old school mechanical bits. (If that makes sense).
Take the OP's (remember him?) original post with regards to DCR . That acronym has elicited both ridicule and insight with regards to it's validity. I've taken from that what I think to be relevant and will pursue it (even if my build turns out to BE imaginary) and see where it takes me.
I'm one who appreciates all of the replies.
It used to be my job to source information. Now it's my job to take that information and assimilate it. 8.4:1 DCR and iron heads? Yesterday I'd say no way. Today, maybe not so much.

Thanks, a big reason i don't rely on DCR as a thing is because it doesnt give me the information i need.
take a 632
16:1
4.6 bore
4.75 stroke
6.7 rod
102 ivc


now try a
598
14:1
4.6 bore
4.5 stroke
6.7 rod
76ivc

both cams are the same size, only difference is intake centerline. Could you load the 632 on pump gas?
why did the 632 make almost 300 more hp granted the dynamic compression ratio is junk?

DCR is never junk if the input data is accurate. They are always useful but sometimes not adequate.

Your posted IVC numbers lack clarity. Are they ABC or BTC? It makes a difference.

[David Redszus]

Continuing on the topic of CAI and ambient temps, part of this build was ceramic coating the headers and intake man. Any thoughts on if this will actually do anything to reduce temps in the engine bay?

I think ceramic coating of headers can make a big difference. I am not so sure about the intake manifold.

paulie

To be effective, a ceramic coating must be very thick. Then the difference in thermal expansion rates becomes
problematic..

A coating applied to the outside of a header does very little since the iron will still absorb heat from the exhaust
gas. Therefore, the thermal barrier coating should be applied to the inside of the header, not the outside surface.

Similarly, with an intake manifold. Evaporating fuel will cool the inlet charge but also cool the manifold.
Coating the inside will be beneficial. Even more useful is to use a polymer manifold, not aluminum, in order
to improved charge density.

[nitro2]

Can you share what the technology is?

Injector timing, valve timing, ignition timing, combustion shape torque management etc.

I don't consider what you've listed as "technology" per se but a different approach. What I was hoping for was a discussion on the science or more importantly a direction on where to find the relevant papers by those who have pioneered this work.

I'm not sure which "you" you were referring to but as far as this "you" (me) is concerned, what I am talking about is new technology, just not new to me (because I have sat on it for quite awhile). It has nothing to do with any sort of fancy footwork with injector/valve/ignition timing etc. It works just fine even for engines that don't have computers, as it is not dependent on the precise juggling of the usual parameters. When applied to really high powered engines with turbos, superchargers, nitrous, nitro etc., power can be turned up a LOT as detonation is near to an impossibility. Sounds wonderful, and it is, and not too complicated, but it is also not legal in normal sanctioning bodies and OEMs would need an infrastructure change before using it. Basically all dressed up and nowhere to go lol.

[ClassAct]

Injector timing, valve timing, ignition timing, combustion shape torque management etc.

I don't consider what you've listed as "technology" per se but a different approach. What I was hoping for was a discussion on the science or more importantly a direction on where to find the relevant papers by those who have pioneered this work.

I'm not sure which "you" you were referring to but as far as this "you" (me) is concerned, what I am talking about is new technology, just not new to me (because I have sat on it for quite awhile). It has nothing to do with any sort of fancy footwork with injector/valve/ignition timing etc. It works just fine even for engines that don't have computers, as it is not dependent on the precise juggling of the usual parameters. When applied to really high powered engines with turbos, superchargers, nitrous, nitro etc., power can be turned up a LOT as detonation is near to an impossibility. Sounds wonderful, and it is, and not too complicated, but it is also not legal in normal sanctioning bodies and OEMs would need an infrastructure change before using it. Basically all dressed up and nowhere to go lol.

That’s a damned shame. Just for the sake of killing the curious cat...can you ballpark a number that the infrastructure change you mentioned would cost?

[David Redszus]

Injector timing, valve timing, ignition timing, combustion shape torque management etc.

I don't consider what you've listed as "technology" per se but a different approach. What I was hoping for was a discussion on the science or more importantly a direction on where to find the relevant papers by those who have pioneered this work.

I'm not sure which "you" you were referring to but as far as this "you" (me) is concerned, what I am talking about is new technology, just not new to me (because I have sat on it for quite awhile). It has nothing to do with any sort of fancy footwork with injector/valve/ignition timing etc. It works just fine even for engines that don't have computers, as it is not dependent on the precise juggling of the usual parameters. When applied to really high powered engines with turbos, superchargers, nitrous, nitro etc., power can be turned up a LOT as detonation is near to an impossibility. Sounds wonderful, and it is, and not too complicated, but it is also not legal in normal sanctioning bodies and OEMs would need an infrastructure change before using it. Basically all dressed up and nowhere to go lol.

I would like to call attention to the fact that we can easily make more power than we can use.
In a given race class, what percentage of available (dyno) power is actually transferred to the ground?

[hysteric]

Injector timing, valve timing, ignition timing, combustion shape torque management etc.

I don't consider what you've listed as "technology" per se but a different approach. What I was hoping for was a discussion on the science or more importantly a direction on where to find the relevant papers by those who have pioneered this work.

I'm not sure which "you" you were referring to but as far as this "you" (me) is concerned, what I am talking about is new technology, just not new to me (because I have sat on it for quite awhile). It has nothing to do with any sort of fancy footwork with injector/valve/ignition timing etc. It works just fine even for engines that don't have computers, as it is not dependent on the precise juggling of the usual parameters. When applied to really high powered engines with turbos, superchargers, nitrous, nitro etc., power can be turned up a LOT as detonation is near to an impossibility. Sounds wonderful, and it is, and not too complicated, but it is also not legal in normal sanctioning bodies and OEMs would need an infrastructure change before using it. Basically all dressed up and nowhere to go lol.

Fair enough.

[hysteric]

I don't consider what you've listed as "technology" per se but a different approach. What I was hoping for was a discussion on the science or more importantly a direction on where to find the relevant papers by those who have pioneered this work.

I'm not sure which "you" you were referring to but as far as this "you" (me) is concerned, what I am talking about is new technology, just not new to me (because I have sat on it for quite awhile). It has nothing to do with any sort of fancy footwork with injector/valve/ignition timing etc. It works just fine even for engines that don't have computers, as it is not dependent on the precise juggling of the usual parameters. When applied to really high powered engines with turbos, superchargers, nitrous, nitro etc., power can be turned up a LOT as detonation is near to an impossibility. Sounds wonderful, and it is, and not too complicated, but it is also not legal in normal sanctioning bodies and OEMs would need an infrastructure change before using it. Basically all dressed up and nowhere to go lol.

I would like to call attention to the fact that we can easily make more power than we can use.
In a given race class, what percentage of available (dyno) power is actually transferred to the ground?

Are you talking about drive train efficiencies?

[David Redszus]

I'm not sure which "you" you were referring to but as far as this "you" (me) is concerned, what I am talking about is new technology, just not new to me (because I have sat on it for quite awhile). It has nothing to do with any sort of fancy footwork with injector/valve/ignition timing etc. It works just fine even for engines that don't have computers, as it is not dependent on the precise juggling of the usual parameters. When applied to really high powered engines with turbos, superchargers, nitrous, nitro etc., power can be turned up a LOT as detonation is near to an impossibility. Sounds wonderful, and it is, and not too complicated, but it is also not legal in normal sanctioning bodies and OEMs would need an infrastructure change before using it. Basically all dressed up and nowhere to go lol.

I would like to call attention to the fact that we can easily make more power than we can use.
In a given race class, what percentage of available (dyno) power is actually transferred to the ground?

Are you talking about drive train efficiencies?

Drive train power losses are a normal factor regardless of power level.

But when we begin to make large power, we quickly become traction limited, whether we know it or not.
Keeping tires on the ground is part of the problem but often dwarfed by tire traction grip limits.

Disregarding aero downforce, how much traction force can a 3000 lb car put to the ground?

[hysteric]

I would like to call attention to the fact that we can easily make more power than we can use.
In a given race class, what percentage of available (dyno) power is actually transferred to the ground?

Are you talking about drive train efficiencies?

Drive train power losses are a normal factor regardless of power level.

But when we begin to make large power, we quickly become traction limited, whether we know it or not.
Keeping tires on the ground is part of the problem but often dwarfed by tire traction grip limits.

Disregarding aero downforce, how much traction force can a 3000 lb car put to the ground?

I'm not there yet. I need to solve the problem of making more power first.

[Orr89rocz]

Water injection would certainly help things when pushing high cyl pressure and temps with fuel that could not handle it on its own

[Orr89rocz]

Thanks, a big reason i don't rely on DCR as a thing is because it doesnt give me the information i need.

...both cams are the same size, only difference is intake centerline. Could you load the 632 on pump gas?
why did the 632 make almost 300 more hp granted the dynamic compression ratio is junk?

I'm going to noodle around with that data and see how it shakes out using the same methodology as my builds. About the only similarity though is that they're engines. At 14:1, I'm sure the dynamics are very different.
This is really just an exercise in keeping myself entertained while hoping for some progress on my own project.

Kinda goes back to what camking said earlier. Cyl fill doesnt end at bdc. Induction dynamics from intake design to header design will change volumetric efficiency. Thus cylinder pressure and temp are greatly changed irrespective of a calculated “closed valve compression ratio” or DCR as most call it. But its not dynamic by any means it simply is a ratio based on when the valve is closed by the cam. Dynamic implies change and changes come from the induction dynamics as rpm changes

[skinny z]

The cylinder may not stop filling at BDC but it most certainly stops when the intake valve closes. Unless there's some weird science going on. And I doubt that.
I think that's what the various calculators and attempting to illustrate. Use them as you might see fit.
From the empirical data we've collected over the years, and I'm not saying I'm part of any huge think tank on the subject, we've learned that there's a definite correlation between the SCR, the IVC (generally demonstrated as DCR) and what works or doesn't work in our applications.

[Nut124]

This whole DCR and the idea of giving an engine more cam to combat detonation risk seems confusing, rather backwards to me. Then again, I'm not a V8 guy.

Is it not the purpose of a cam profile is to maximize cylinder fill and pressure, VE, for max torque/HP? If a cam is used to reduce DCR, due to detonation concerns, then SCR is too high to start with. Right?

[skinny z]

Just elaborate on the "what works in our application" comment above, it seems we've found the upper end limits. That is, go beyond this number and the timing has to be dialed back from an ideal or measures out in place like water or meth injection to help keep detonation in line.
What I haven't explored, other than by mis-design, is what the lower limits are for acceptable results.
It would seem from some of the posts here, that the higher output engines, with very high SCRs, tend to care less about the DCR (as it were).
It would be interesting see what a 7.6:1 vs a 9.6:1 test result might be with respect to DCR. But would the offset be created via lowering the static compression or by moving the IVC?