blown engine
02-06-2017, 05:00 PM
#887
There are a few points:
- Mainly because I was afraid of CEL and the DME not able to compensate with 11.1% displacement increase
- I asked Jake and Tony and both of them recommended 3.8 (between 3.6 and 3.8)
- Without modifying the intake and exhaust, I'm not sure I can make a 4.0 that could live up to its full potential
- 3.8 is proven and there are quite a few here on RL who did that, either with Jake or other builders
- Mainly because I was afraid of CEL and the DME not able to compensate with 11.1% displacement increase
- I asked Jake and Tony and both of them recommended 3.8 (between 3.6 and 3.8)
- Without modifying the intake and exhaust, I'm not sure I can make a 4.0 that could live up to its full potential
- 3.8 is proven and there are quite a few here on RL who did that, either with Jake or other builders
02-06-2017, 05:32 PM
#888
Drifting
Rebuilt M96 benchmarks
This is the only source IIRC for any data for the ideal performance of a newly rebuilt M96.It is an invaluable benchmark for any who rebuild an M96 and wonder how to asses the success or otherwise of the work,money and time.
But it may be important to note that this engine has run 90 miles and 2+hours in several sessions.,including a Smog Test.
In this link 200+ miles is mentioned !
http://986forum.com/forums/performan...emissions.html
I found that the Durametric readings taken just a few minutes after running for the first time after the rebuild were misleading.It needs a while(how long?) for things to settle and be read multiple times by the DME before a meaningful result is obtained?
Then there is the issue of the Drive Cycle before Smog Testing for all the Readiness Monitors to set. How did Ahsai get the Drive Cycle done so fast?
But it may be important to note that this engine has run 90 miles and 2+hours in several sessions.,including a Smog Test.
In this link 200+ miles is mentioned !
http://986forum.com/forums/performan...emissions.html
I found that the Durametric readings taken just a few minutes after running for the first time after the rebuild were misleading.It needs a while(how long?) for things to settle and be read multiple times by the DME before a meaningful result is obtained?
Then there is the issue of the Drive Cycle before Smog Testing for all the Readiness Monitors to set. How did Ahsai get the Drive Cycle done so fast?
Ok, here's the update some of you have been waiting for!
Car passed smog and the 3.8 indeed pulls strong! Very similar to my '03 3.6 below 3k but above 3k, it's pulling very strongly all the way to 6k (I have not touched the redline yet). Put 90 miles on it so far and it's fantastic. The idle is silky smooth. Smoother than my '03 for sure. I guess my meticulous part swapping piston/rod/pin/rings balancing paid off!
The engine cranks with very even compression and it fires right up with gusto cold or warm. I can barely feel it idling. All the fuel trims are practically 0.
FRA is 1.02 on bank 1 (i.e., 2% of fuel is added under heavy load)
FRA is 0.99 on bank 2 (i.e., 1% of fuel is pulled under heavy load)
RKAT is 0.66% on bank 1 (i.e., 0.66% of fuel is added at idle)
RKAT is 1.41% on bank 2 (i.e., 1.41% of fuel is added at idle)
Cam deviations are 3.48 on bank 1 and 2.58 on bank 2. I'm not worrying as I can always adjust them later if needed. Rough cylinder measurements at idle hovers around 0.0 most of the time and it goes to at most 0.7 for all cylinders! Again, very very smooth.
MAF is ~5.2g/s at idle as compared to ~5g/s for my 3.6. It make sense because 3.8 is about 5.5% increase in displacement so it sucks in about that much more of air (I know it's not linear but it's darn close). The fuel trims above also have answered a question I have had for a long time. Are they w.r.t the measured air mass or an absolute air mass expected at a specific rpm? The answer is the former. It makes a lot of sense because each engine has some variations so some breath better than the others and the DME will have to be able to compensate and handle them. With only 5.5% increase, the DME has no problems handling the extra 200cc. It just adds more fuel (compared to 3.6) to reach the stoichiometric ratio. The fact that the fuel trims are close to 0 means everything is good.
Coolant temp and oil pressure are also great and normal. Alternator voltage output looks great too (I installed a brand new y-cable).
Now the chassis itself needs some attention. The tires are all-season. The front tires are 8yrs old! Gonna put a set of Continental DW on. The left radiator shroud so that will be replaced soon. The transmission is great. The suspension feels tired but coming out from my x74, everything else will feel very sloppy.
Overall, the car is in excellent shape.
Next stop is 300 miles. Oil change and the oil pan will be dropped for inspection, along with other inspections.
Car passed smog and the 3.8 indeed pulls strong! Very similar to my '03 3.6 below 3k but above 3k, it's pulling very strongly all the way to 6k (I have not touched the redline yet). Put 90 miles on it so far and it's fantastic. The idle is silky smooth. Smoother than my '03 for sure. I guess my meticulous part swapping piston/rod/pin/rings balancing paid off!
The engine cranks with very even compression and it fires right up with gusto cold or warm. I can barely feel it idling. All the fuel trims are practically 0.
FRA is 1.02 on bank 1 (i.e., 2% of fuel is added under heavy load)
FRA is 0.99 on bank 2 (i.e., 1% of fuel is pulled under heavy load)
RKAT is 0.66% on bank 1 (i.e., 0.66% of fuel is added at idle)
RKAT is 1.41% on bank 2 (i.e., 1.41% of fuel is added at idle)
Cam deviations are 3.48 on bank 1 and 2.58 on bank 2. I'm not worrying as I can always adjust them later if needed. Rough cylinder measurements at idle hovers around 0.0 most of the time and it goes to at most 0.7 for all cylinders! Again, very very smooth.
MAF is ~5.2g/s at idle as compared to ~5g/s for my 3.6. It make sense because 3.8 is about 5.5% increase in displacement so it sucks in about that much more of air (I know it's not linear but it's darn close). The fuel trims above also have answered a question I have had for a long time. Are they w.r.t the measured air mass or an absolute air mass expected at a specific rpm? The answer is the former. It makes a lot of sense because each engine has some variations so some breath better than the others and the DME will have to be able to compensate and handle them. With only 5.5% increase, the DME has no problems handling the extra 200cc. It just adds more fuel (compared to 3.6) to reach the stoichiometric ratio. The fact that the fuel trims are close to 0 means everything is good.
Coolant temp and oil pressure are also great and normal. Alternator voltage output looks great too (I installed a brand new y-cable).
Now the chassis itself needs some attention. The tires are all-season. The front tires are 8yrs old! Gonna put a set of Continental DW on. The left radiator shroud so that will be replaced soon. The transmission is great. The suspension feels tired but coming out from my x74, everything else will feel very sloppy.
Overall, the car is in excellent shape.
Next stop is 300 miles. Oil change and the oil pan will be dropped for inspection, along with other inspections.
Last edited by Schnell Gelb; 02-07-2017 at 05:35 PM.
02-06-2017, 06:23 PM
#889
Rennlist Member
Can you explain the cam deviations and your ability to "adjust" this. I was thinking of deviations as "slop" but apparently it is more a deviation from ideal cam timing..?? So you will re-time the cams to improve/reduce the deviation? And why wasn't the initial timing correct?
02-06-2017, 06:33 PM
#890
Drifting
I had similar results for Bank 1 after the rebuild..
The smart guys (not me) said - Converted to crankshaft degrees, these deviations are trivial. But there is an interesting question of if you should focus more on "Actual Degrees"-via Durametric than Deviations. And then there is the 'is it degrees advanced or retarded " question - and when does it throw a code. But I'll let Ahsai answer.
Note - always buy extra scavenge pump O rings !
The smart guys (not me) said - Converted to crankshaft degrees, these deviations are trivial. But there is an interesting question of if you should focus more on "Actual Degrees"-via Durametric than Deviations. And then there is the 'is it degrees advanced or retarded " question - and when does it throw a code. But I'll let Ahsai answer.
Note - always buy extra scavenge pump O rings !
02-06-2017, 11:04 PM
#891
IMO, 90 miles is more than enough to get some relevant readings. In general, after DME reset, it doesn't take that long for the adjustments (e.g., fuel trims) to readjust to the previous values before the reset. In a newly rebuilt engine though, the new parts are breaking in so it may take longer to converge to some final readings.
It didn't take 90 miles to get the emission ready. I could have done it in a couple of drives but I needed to do the break in routine where I will be doing WOT pulls and engine breaking often and that will exceed 3k rpm for sure. Anytime above 3k, those emission tests will be halted/restarted.
By adjustment, I meant re-timing. However, I don't see the need to do that if those values stay where they are. My understanding is the DME expects to see a certain cam position relative to the crank position. The crank position is picked up by crank position sensor sensing the teeth on the flywheel and the cam position is picked up by the cam position sensor sensing the reluctor on the intake cam. The DME expects a certain offset between the two if the timing is right on. However, if the cam is lagging behind a bit, you will have negative cam deviation. Porsche spec is +/- 6 degrees. The reason is this deviation will become more negative as the cam pads wear and timing chain stretched as they age.
Now why I didn't get 0 degree cam deviation? There could be multiple factors. One major factor could be because I didn't use the mechanical chain tensioner tool that insert into the chain tensioner holes to tighten up the timing chains. I used the regular chain tensioner pumped up with oil. However, I suspect even with those tools, one most likely won't get 0. One very easy way I can think of to avoid this is to fab up a special timing pulley that has a hole that is ~2 degrees behind the normal TDC hole on the stock pulley. That way you pre-retard the crank by 2 degrees or so when timing the engine.
It didn't take 90 miles to get the emission ready. I could have done it in a couple of drives but I needed to do the break in routine where I will be doing WOT pulls and engine breaking often and that will exceed 3k rpm for sure. Anytime above 3k, those emission tests will be halted/restarted.
By adjustment, I meant re-timing. However, I don't see the need to do that if those values stay where they are. My understanding is the DME expects to see a certain cam position relative to the crank position. The crank position is picked up by crank position sensor sensing the teeth on the flywheel and the cam position is picked up by the cam position sensor sensing the reluctor on the intake cam. The DME expects a certain offset between the two if the timing is right on. However, if the cam is lagging behind a bit, you will have negative cam deviation. Porsche spec is +/- 6 degrees. The reason is this deviation will become more negative as the cam pads wear and timing chain stretched as they age.
Now why I didn't get 0 degree cam deviation? There could be multiple factors. One major factor could be because I didn't use the mechanical chain tensioner tool that insert into the chain tensioner holes to tighten up the timing chains. I used the regular chain tensioner pumped up with oil. However, I suspect even with those tools, one most likely won't get 0. One very easy way I can think of to avoid this is to fab up a special timing pulley that has a hole that is ~2 degrees behind the normal TDC hole on the stock pulley. That way you pre-retard the crank by 2 degrees or so when timing the engine.
Last edited by Ahsai; 02-07-2017 at 12:24 AM.
02-07-2017, 01:26 AM
#892
I had similar results for Bank 1 after the rebuild..
The smart guys (not me) said - Converted to crankshaft degrees, these deviations are trivial. But there is an interesting question of if you should focus more on "Actual Degrees"-via Durametric than Deviations. And then there is the 'is it degrees advanced or retarded " question - and when does it throw a code. But I'll let Ahsai answer.
Note - always buy extra scavenge pump O rings !
The smart guys (not me) said - Converted to crankshaft degrees, these deviations are trivial. But there is an interesting question of if you should focus more on "Actual Degrees"-via Durametric than Deviations. And then there is the 'is it degrees advanced or retarded " question - and when does it throw a code. But I'll let Ahsai answer.
Note - always buy extra scavenge pump O rings !
02-07-2017, 12:14 PM
#893
Drifting
My deviation is negative 2.5 degrees on Bank One.
Your photo of the wire pointer trick arrived after I had installed the engine
Thanks for taking an interest.
I have already ordered the big O rings to correct it ,eventually. I am preoccupied with bigger issues unrelated(?) -Misfire on 1,2,3. Injector connections checked,coils ,plugs are new,no mix-ups in the wiring. If all 3 are misfiring it suggests a fault at a point common to all three
Your photo of the wire pointer trick arrived after I had installed the engine
Thanks for taking an interest.
I have already ordered the big O rings to correct it ,eventually. I am preoccupied with bigger issues unrelated(?) -Misfire on 1,2,3. Injector connections checked,coils ,plugs are new,no mix-ups in the wiring. If all 3 are misfiring it suggests a fault at a point common to all three
02-07-2017, 01:40 PM
#894
My deviation is negative 2.5 degrees on Bank One.
Your photo of the wire pointer trick arrived after I had installed the engine
Thanks for taking an interest.
I have already ordered the big O rings to correct it ,eventually. I am preoccupied with bigger issues unrelated(?) -Misfire on 1,2,3. Injector connections checked,coils ,plugs are new,no mix-ups in the wiring. If all 3 are misfiring it suggests a fault at a point common to all three
Your photo of the wire pointer trick arrived after I had installed the engine
Thanks for taking an interest.
I have already ordered the big O rings to correct it ,eventually. I am preoccupied with bigger issues unrelated(?) -Misfire on 1,2,3. Injector connections checked,coils ,plugs are new,no mix-ups in the wiring. If all 3 are misfiring it suggests a fault at a point common to all three
The crank pulley diameter is 148.6mm, circumference is 466.8mm. The notch on the pulley for TDC #1 is about 2mm wide and that’s already 1.54 degrees. Having said that, 4mm will give ~3 degrees and you (we) can't be possibly be 4mm off of the pulley TDC mark. I suspect the deviation comes from somewhere else.
I wonder if a new flywheel is also part of the equation because of manufacturing variation of the positions of the missing teeth, which the DME uses to locate TDC cyl #1. Now I regretted a bit not measuring the true TDC (by using a dial gauge on the top of the piston) w.r.t the pulley TDC hole.
Re your misfire on cyl 1, 2, 3, have you checked for air leak and what are your fuel trims?
02-07-2017, 01:49 PM
#895
Drifting
Thank you for your thoughtful response Ahsai.
I am 'on duty' until Sunday and hope to do more diagnosis then. I shall answer your questions then I hope.
I agree about the TDC measurement with a dial indicator . The timing issue is so tedious to rectify after installation that any double checking dome with the engine on the stand is wise advice.
I am 'on duty' until Sunday and hope to do more diagnosis then. I shall answer your questions then I hope.
I agree about the TDC measurement with a dial indicator . The timing issue is so tedious to rectify after installation that any double checking dome with the engine on the stand is wise advice.
02-08-2017, 01:06 PM
#898
02-08-2017, 01:16 PM
#899
Drifting
or the long block route?
http://www.ebay.com/itm/Porsche-996-...lUBh2t&vxp=mtr
a little more work?
http://www.ebay.com/itm/00-Carrera-9...1X20Ab&vxp=mtr
or as an example the real deal but 3.2:
http://www.ebay.com/itm/PORSCHE-OEM-...hYmJzt&vxp=mtr
http://www.ebay.com/itm/Porsche-996-...lUBh2t&vxp=mtr
a little more work?
http://www.ebay.com/itm/00-Carrera-9...1X20Ab&vxp=mtr
or as an example the real deal but 3.2:
http://www.ebay.com/itm/PORSCHE-OEM-...hYmJzt&vxp=mtr
02-08-2017, 10:18 PM
#900
Rennlist Member
Originally Posted by Ahsai
Thanks! What happened to your engine again? Short block from the dealer is still quite expensive and you won't have the option to go 3.8
Your thoughts