Cast EFR 8374 IWG Large StreetPort FC3S Dyno 503rwhp @ 17.5psi
01-30-17 | 03:29 PM
#27
Thread Starter
Joined: Dec 2001
Posts: 7,094
Likes: 122
From: Twin Cities, MN
In the past yes, I broke a S4 t2 plate at 450rwhp 10 years ago on stock dowels/tension bolts with 2 stages of 50/50 water alcohol.
Literally slapped a new S5 big dowel rear pate on and our 10mm stud kit and it did not happen again...
Literally slapped a new S5 big dowel rear pate on and our 10mm stud kit and it did not happen again...
01-31-17 | 11:22 AM
#28
"Elusive, not deceptive!”
Joined: May 2007
Posts: 930
Likes: 13
From: Slidell, LA
I haven't done any testing with E85 so I have no real-world detonation limits to share.
Each power event is different as you accelerate to 8000 rpm it only takes a few to set up preignition and detonation.
My thought is to always use water in the mix to delay detonation.
This is my 8374 on the ragged edge. Boost is 18 psi with the correct amount of advance for 93 oct.
But the pressure is going to high (1430 psi). I feel that the Water/meth stabilizes the burn rate and allows this engine to live at these pressures (and higher).
I also endorse the 3rd gen plates.
Each power event is different as you accelerate to 8000 rpm it only takes a few to set up preignition and detonation.
My thought is to always use water in the mix to delay detonation.
This is my 8374 on the ragged edge. Boost is 18 psi with the correct amount of advance for 93 oct.
But the pressure is going to high (1430 psi). I feel that the Water/meth stabilizes the burn rate and allows this engine to live at these pressures (and higher).
I also endorse the 3rd gen plates.
01-31-17 | 02:55 PM
#30
Exhaust Manifold Leak
Joined: Jun 2005
Posts: 766
Likes: 26
From: western europe
I haven't done any testing with E85 so I have no real-world detonation limits to share.
Each power event is different as you accelerate to 8000 rpm it only takes a few to set up preignition and detonation.
My thought is to always use water in the mix to delay detonation.
This is my 8374 on the ragged edge. Boost is 18 psi with the correct amount of advance for 93 oct.
But the pressure is going to high (1430 psi). I feel that the Water/meth stabilizes the burn rate and allows this engine to live at these pressures (and higher).
I also endorse the 3rd gen plates.
Each power event is different as you accelerate to 8000 rpm it only takes a few to set up preignition and detonation.
My thought is to always use water in the mix to delay detonation.
This is my 8374 on the ragged edge. Boost is 18 psi with the correct amount of advance for 93 oct.
But the pressure is going to high (1430 psi). I feel that the Water/meth stabilizes the burn rate and allows this engine to live at these pressures (and higher).
I also endorse the 3rd gen plates.
What Ign angle you have at this cycle?, to get an rough idea of ignition delay.
Would you say in this condition that you are knock limited, or maximum chamber pressure limited?
02-01-17 | 03:01 PM
#31
"Elusive, not deceptive!”
Joined: May 2007
Posts: 930
Likes: 13
From: Slidell, LA
Rub,
My guess is max chamber pressure. But I am a big chicken when it comes to blowing up engines.
On the earlier attachment did you notice the pulsing after peak pressure ... that is getting close to a detonation profile I think.
Nice! the other pressure trace, I guess is compression without combustion?
Correct
1400 psi is somewhere what low-mid spec turbo piston engine run these days.
We have very little info on what the structural limit is. The highest I have experienced is 1600 psi.
What Ign angle you have at this cycle?, to get an rough idea of ignition delay.
Attached are two burn rate cycles.... the first is a normal... followed by one with pre-ignition. It takes about 10 deg for the burn kernal to start to register on the sensor, the second is caused by (I think) active radicals from exhaust reversion and it starts 22 deg earlier with the same computer directed timing.
Would you say in this condition that you are knock limited, or maximum chamber pressure limited?
Correct
1400 psi is somewhere what low-mid spec turbo piston engine run these days.
We have very little info on what the structural limit is. The highest I have experienced is 1600 psi.
What Ign angle you have at this cycle?, to get an rough idea of ignition delay.
Attached are two burn rate cycles.... the first is a normal... followed by one with pre-ignition. It takes about 10 deg for the burn kernal to start to register on the sensor, the second is caused by (I think) active radicals from exhaust reversion and it starts 22 deg earlier with the same computer directed timing.
Would you say in this condition that you are knock limited, or maximum chamber pressure limited?
On the earlier attachment did you notice the pulsing after peak pressure ... that is getting close to a detonation profile I think.
Last edited by Barry Bordes; 02-01-17 at 03:11 PM.
02-01-17 | 03:19 PM
#32
Exhaust Manifold Leak
Joined: Jun 2005
Posts: 766
Likes: 26
From: western europe
Possible, to get a feel what it looks like I would run the motor into knock at part load, where it shouldnt cause immediate damage. to get a feel about the frequency of the oscialltion.
At work we use knock amplitude or knock peak to peak. this get calculated for as the difference between the unfiltered pressure trace and the pressure trace filtered over the average of the last x measurements (usually around 20 measurements with 0.1 deg resolution, varying with rpm). as a calibration guideline we use rpm/1000 for knock peak to peak signal in bar.
In the first pic of you previous post, do you have any idea why the chamrber pressure lies below the compression trace near TDC? do you think the apex is lifting? What funny is that on these old skool paper comrpession tester you can see where the seal passes the leading plug hole.
At work we use knock amplitude or knock peak to peak. this get calculated for as the difference between the unfiltered pressure trace and the pressure trace filtered over the average of the last x measurements (usually around 20 measurements with 0.1 deg resolution, varying with rpm). as a calibration guideline we use rpm/1000 for knock peak to peak signal in bar.
In the first pic of you previous post, do you have any idea why the chamrber pressure lies below the compression trace near TDC? do you think the apex is lifting? What funny is that on these old skool paper comrpession tester you can see where the seal passes the leading plug hole.
02-02-17 | 10:59 AM
#33
"Elusive, not deceptive!”
Joined: May 2007
Posts: 930
Likes: 13
From: Slidell, LA
"In the first pic of you previous post, do you have any idea why the chamber pressure lies below the compression trace near TDC?"
One is theoretical and the other is actual collected pressure data.
Great questions .. but let me apologize for taking this rabbit track away from Turblown's thread.
I should find some time to make a separate compression testing thread.
Barry
One is theoretical and the other is actual collected pressure data.
Great questions .. but let me apologize for taking this rabbit track away from Turblown's thread.
I should find some time to make a separate compression testing thread.
Barry
11-13-17 | 12:16 PM
#35
Car is back togeather finally, scope creep ended up including a paint job....BMW sakhir orange metallic...will get it back on the dyno in the spring, it's now down for it's long winter's nap...
Last edited by RockLobster; 11-25-17 at 03:34 PM. Reason: Picture problems
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