What Engine for 500BHP
Discussion
chuntington101 said:
Is there much meat left around the studs? From the above pics there looks to be form the studs you can see. Is it not worth getting the studs and current inserts machined out and larger ones (both studs and inserts) fitted?
That is a possibility - though I would like to try it with a spare block (if I had one) I am going to ask on the alfa forum about the possibility....I'd want to get a spare block and chop it up to look at the CSA in various critical locations too! (no point having the worlds strongest stiffest studs, if they are threaded into cheese.......
(btw, welcome to the world of high performance engine development! Having spent many years and getting far too many grey hairs trying to coax unfeasible amounts to power and torque from various engines, the one thing i would say is "Take nothing for granted, check everything yourself"........ ;-)
(btw, welcome to the world of high performance engine development! Having spent many years and getting far too many grey hairs trying to coax unfeasible amounts to power and torque from various engines, the one thing i would say is "Take nothing for granted, check everything yourself"........ ;-)
Jesus you bunch of wallies are making a right meal of all this with yer clamping loads, composite gasket, dodgy waterway and other assorted b0ll0cks. Good job there's one 'proper' engine builder in here to put you and the OP straight 
It's a simple case of mild det. You can see it clearly in the combustion chamber between the inlet valves. The mottled gray "shot blasted" looking finish. It's blown the carbon off the squish area and over time pushed the gasket out and fretted the head underneath the fire ring. Det that mild is not going to be an immediate failure but it'll always eventually get you in the long run.
You just need to back the CR off a tad and/or the ignition advance on boost and at peak torque. The det is probably only happening briefly at one specific point of high boost and mid range rpm and then the engine is revving past it. If it were more severe or constant the chamber damage would be worse with pock marking of the aluminium like little centre punch marks and corresponding damage on the piston crowns and eventually top ring land failure.
Now then, off to the the naughty step Max and the rest of you. You can come out and play again when I say so after you've apologised for all the silliness and promised to be good little boys in future. You DO NOT want me to have to start taking names and kicking arses!
It's a simple case of mild det. You can see it clearly in the combustion chamber between the inlet valves. The mottled gray "shot blasted" looking finish. It's blown the carbon off the squish area and over time pushed the gasket out and fretted the head underneath the fire ring. Det that mild is not going to be an immediate failure but it'll always eventually get you in the long run.
You just need to back the CR off a tad and/or the ignition advance on boost and at peak torque. The det is probably only happening briefly at one specific point of high boost and mid range rpm and then the engine is revving past it. If it were more severe or constant the chamber damage would be worse with pock marking of the aluminium like little centre punch marks and corresponding damage on the piston crowns and eventually top ring land failure.
Now then, off to the the naughty step Max and the rest of you. You can come out and play again when I say so after you've apologised for all the silliness and promised to be good little boys in future. You DO NOT want me to have to start taking names and kicking arses!
LOL^^ Mr Subtle as always eh Puma!
IMO (i reserve the right to be wrong btw..... ;-) any 'mild' det man enough to push a head gasket backwards assuming a properly clamped and supported gasket, would also damage both that gasket, and probably the ring lands too. Also, in this case, we don't know if the(any) det was pre or post gasket failure. Once you get coolant in the chamber, all bets are off.
I can't tell from those pics if the mottling is really evidence of det, or just dirt/ particles reflecting in the flash. For example, a similar looking pattern is present in some areas completely outside the combustion chamber between the cyls........ And with a coolant leak into the chamber, the carbon will have been removed anyway.
And finally, if you don't fix the gasket now, you will for ever be worried about a repeat. In the ideal world, you'd have the engine so perfectly mapped and controlled that you'd never get any abnormal combustion. But unless you are an OEM, with a state of the art ems, and a team of 100's to develop and calibrate it, the chances are your (high boost) engine could det at some point (wrong temp compensations, hot day, poor fuel, iffy transient fuelling and about a million other reasons etc etc etc)
So, in summary:
COULD you run the gasket as it is? YES
SHOULD you run the gasket as it is? NO (IMO!)
;-)
IMO (i reserve the right to be wrong btw..... ;-) any 'mild' det man enough to push a head gasket backwards assuming a properly clamped and supported gasket, would also damage both that gasket, and probably the ring lands too. Also, in this case, we don't know if the(any) det was pre or post gasket failure. Once you get coolant in the chamber, all bets are off.
I can't tell from those pics if the mottling is really evidence of det, or just dirt/ particles reflecting in the flash. For example, a similar looking pattern is present in some areas completely outside the combustion chamber between the cyls........ And with a coolant leak into the chamber, the carbon will have been removed anyway.
And finally, if you don't fix the gasket now, you will for ever be worried about a repeat. In the ideal world, you'd have the engine so perfectly mapped and controlled that you'd never get any abnormal combustion. But unless you are an OEM, with a state of the art ems, and a team of 100's to develop and calibrate it, the chances are your (high boost) engine could det at some point (wrong temp compensations, hot day, poor fuel, iffy transient fuelling and about a million other reasons etc etc etc)
So, in summary:
COULD you run the gasket as it is? YES
SHOULD you run the gasket as it is? NO (IMO!)
;-)
Edited by anonymous-user on Thursday 5th September 11:48
Max_Torque said:
LOL^^ Mr Subtle as always eh Puma!
I can't tell from those pics if the mottling is really evidence of det, or just dirt/ particles reflecting in the flash. For example, a similar looking pattern is present in some areas completely outside the combustion chamber between the cyls........ And with a coolant leak into the chamber, the carbon will have been removed anyway.
I tried to photograph the surface of the heads, but its not easy, but see belowI can't tell from those pics if the mottling is really evidence of det, or just dirt/ particles reflecting in the flash. For example, a similar looking pattern is present in some areas completely outside the combustion chamber between the cyls........ And with a coolant leak into the chamber, the carbon will have been removed anyway.
Edited by Max_Torque on Thursday 5th September 11:48
The heads are marked with small pock marks on the inlet side & are notably rougher than the rest of the head. A couple of cylinders the head has been eroded away slightly at the edge of the combustion area. The heads were previously aquablasted, which gives a matt/mottled look to the surface. I left the surface like that assuming (rightly or wrongly) that it would help grip the gasket..
The photos of the edge of the piston show that it is also rough & pock marked - I think I need to pull the pistons to get a better look, but dont have time today, hopefully I will manage tomorrow....
Max_Torque said:
I can't tell from those pics if the mottling is really evidence of det,
I understand how hard all this is for you, believe me, and I sympathise and yes, I feel a little sad for you and the other mortals who aren't tuning gods like wot I am and for whom it all comes so easily and obviously.Still, it's a cross I have to learn to bear, being so fvcking good at what I do. But don't get discouraged. You're learning a little more every day and that's the main thing and I'm always here to pick up the pieces and set you straight when you guess wrong. No need to thank me though. Dispensing my wisdom and educating the masses is payment enough for me.
Edited by Pumaracing on Thursday 5th September 15:16
andygtt said:
puma... can you impart your godlike wisdom and let me know what happened to my turbo V6?, was this det 
Yep. That's the type of det wot happens when a nut in the air filter box unscrews and gets sucked into the engine or the tip of a spark plug breaks off and bounces around for a while.Ok, with those better pics, i'd agree and say there has definitely been detonation occurring. Is it on all the cyls equally? Or just the one with the completely failed gasket? (we don't know if the det was pre or post gasket failure). I would expect the cyls furthest from the water pump inlet to det the hardest (being the warmest).
However, this doesn't really change anything for me. That engine still has a weak spot, and i'd suggest will struggle to be a 500bhp engine for very long with a poorly supported fire ring area.
Looking at the general size and geo of the engine (liners, studs, lands etc) i would suggest that a Pmax limit of 95bar would be about right in production spec. Producing something like 2x as much power as std, you need something a lot more robust ;-)
On the WRC scooby, we regularly would see 160bar Pmax, with another 60bar of KPmax on top! And the liners regularly came back tulip shaped at the top.........
However, this doesn't really change anything for me. That engine still has a weak spot, and i'd suggest will struggle to be a 500bhp engine for very long with a poorly supported fire ring area.
Looking at the general size and geo of the engine (liners, studs, lands etc) i would suggest that a Pmax limit of 95bar would be about right in production spec. Producing something like 2x as much power as std, you need something a lot more robust ;-)
On the WRC scooby, we regularly would see 160bar Pmax, with another 60bar of KPmax on top! And the liners regularly came back tulip shaped at the top.........
Pumaracing said:
andygtt said:
puma... can you impart your godlike wisdom and let me know what happened to my turbo V6?, was this det
Yep. That's the type of det wot happens when a nut in the air filter box unscrews and gets sucked into the engine or the tip of a spark plug breaks off and bounces around for a while.
;-)
or, you might be doing it again, but properly, in a few months.......
Sorry, but i subscribe to the Kelly Johnson "don't wound problems, kill them, stone dead first time" ethos !
Sorry, but i subscribe to the Kelly Johnson "don't wound problems, kill them, stone dead first time" ethos !
KellyJohnsonSkunkworks said:
The final thing you need to know is don’t half-heartedly wound problems – kill them dead. That’s all there is to it. Now you can run this goddamn place. Now, go home and pour yourself a drink.
http://www.speedhunters.com/2013/07/greatest-veloc...
I think I need to talk to this guy, he is running 617WHP on the gasket I just blew. Not sure on his tightening or stud spec. But looks more like something Failed on my engine....
I still think I need to go with the best build I can to avoid any future issues - as well as finding and fixing the issue that caused the det in the first place.
I think I need to talk to this guy, he is running 617WHP on the gasket I just blew. Not sure on his tightening or stud spec. But looks more like something Failed on my engine....
I still think I need to go with the best build I can to avoid any future issues - as well as finding and fixing the issue that caused the det in the first place.
Assuming you haven't got knock control on your ecu, you can still fit some knock sensors and use them to roughly estimate the knocking energies for you engine, as follows:
1) fit a pair of knock sensors on the heads (hopefully there are some bosses for them as used by the std cars ems system?)
2) Wire the sensors through ideally a band pass active filter (2nd order - 5Khz to 22Khz) or second best through a low pass anti-aliasing filter (-3db @ ~22Khz), and into a laptop sound card (L & R channel so you can log two sensors simultaneously). Using a audio program (plenty of freeware on net) log both sensors at 44Khz stereo.
3) Fill car with the absolute best quality fuel you can find (say 102 octaine ideally) to try to eliminate any detonation that might occur (you might have to use a global spark retard trim if you can't find 102 fuel, but better to keep the same ignition angle if possible)
4) Log a few sec of the data on the sound card at a matrix of load and speed points
5) Fill car with the normal fuel you run, (having purged out the previous high octaine fuel through very well indeed ) and repeat the logging matrix of points.
Then,
either
6a) Use a .wav to .csv convertor to get the raw signal values. Post process (with excel possibly, but matlab ideally) this data using a Fast Fourier Transform (FFT) to recover the signal energy in the frequency domain.
or
6b) Replay the .wav files through a pc based digital signal processor that has an FFT function.
7) Compare the signal energy levels with your "no det" case. Of course, this doesn't give you a correlation to actual cylinder pressure or knocking pressure, but it should give you a good indication of what sort of levels of high frequency knocking energy is present in your engine, even if you can't hear it with the human ear!
1) fit a pair of knock sensors on the heads (hopefully there are some bosses for them as used by the std cars ems system?)
2) Wire the sensors through ideally a band pass active filter (2nd order - 5Khz to 22Khz) or second best through a low pass anti-aliasing filter (-3db @ ~22Khz), and into a laptop sound card (L & R channel so you can log two sensors simultaneously). Using a audio program (plenty of freeware on net) log both sensors at 44Khz stereo.
3) Fill car with the absolute best quality fuel you can find (say 102 octaine ideally) to try to eliminate any detonation that might occur (you might have to use a global spark retard trim if you can't find 102 fuel, but better to keep the same ignition angle if possible)
4) Log a few sec of the data on the sound card at a matrix of load and speed points
5) Fill car with the normal fuel you run, (having purged out the previous high octaine fuel through very well indeed ) and repeat the logging matrix of points.
Then,
either
6a) Use a .wav to .csv convertor to get the raw signal values. Post process (with excel possibly, but matlab ideally) this data using a Fast Fourier Transform (FFT) to recover the signal energy in the frequency domain.
or
6b) Replay the .wav files through a pc based digital signal processor that has an FFT function.
7) Compare the signal energy levels with your "no det" case. Of course, this doesn't give you a correlation to actual cylinder pressure or knocking pressure, but it should give you a good indication of what sort of levels of high frequency knocking energy is present in your engine, even if you can't hear it with the human ear!
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