- Joined
- Sep 6, 2003
- Messages
- 492
Two new racecars in NZ
- Thread starter Frans
- Start date
I would try it a it is. Might have to put the timing forward a degree or two, it may not make that much difference on total power output, but will de-stress the motor a bit--- You can't win 'em all...........
I can't remember how many heads you have! Can you build the dry-sump engine without this head? Can you get satisfactory performance from 12.07:1 in some other way?
Is it possible to heat-treat the softened head? I read somewhere that this is possible but expensive. Way beyond my skill/experience level.
What a problem. Too MUCH metal on the head!!!!
Is it possible to heat-treat the softened head? I read somewhere that this is possible but expensive. Way beyond my skill/experience level.
What a problem. Too MUCH metal on the head!!!!
In my mind the percentage gain in performance from 12.07 to 12.4 would be quite small, maybe 2%. I have no testing to prove this, only that compression ratio gain has diminishing returns at that level, although also dependant on the fuel used.
What thickness head gasket do you use? Some years ago I had a custom one made for a BMW E30 M3. The standard gasket was 72 thou compressed, the new one started at 40thou, although of course this can introduce valve clearance problems with the size cam you are likely to be using, but no different to removing material from the head face. A lot of work, but the block and liners could be machined to allow the pistons to protrude into the head gasket thickness area to gain some more compression.
What thickness head gasket do you use? Some years ago I had a custom one made for a BMW E30 M3. The standard gasket was 72 thou compressed, the new one started at 40thou, although of course this can introduce valve clearance problems with the size cam you are likely to be using, but no different to removing material from the head face. A lot of work, but the block and liners could be machined to allow the pistons to protrude into the head gasket thickness area to gain some more compression.
Be nice to get you and Frans together!
Hi,
I did some more checking in the cylinder and forgot that I made the pistons 0.9mm below the deck because of the old head being so thin. That is 0.4 lower than the factor I used in my calcs. That changed everything to a new low CR.
I have decided and calculated that I need to take 0.6mm off to get to a respectable 12.1:1 CR as Dauphproto suggested. That will leave me with a bit for future mishaps.
Thanks for the feedback, it helped a lot.
Frans.
I did some more checking in the cylinder and forgot that I made the pistons 0.9mm below the deck because of the old head being so thin. That is 0.4 lower than the factor I used in my calcs. That changed everything to a new low CR.
I have decided and calculated that I need to take 0.6mm off to get to a respectable 12.1:1 CR as Dauphproto suggested. That will leave me with a bit for future mishaps.
Thanks for the feedback, it helped a lot.
Frans.
Hi,
The head has been skimmed and it is now a respectable 12.18:1 compression ratio. I have checked the spring tensions and there is no difference in pressure than the last rebuild. I thought that I had to do it because of the different head. The head is now assembled and waiting to be fitted after I'm finished with the bottom end.
I ordered rod and main bearings a while ago but only the rod bearings arrived. After removal and checking the mains, they can and will be re-used because I can't wait any longer. They are however in pristine condition.
That cannot be said about the rod bearings. I have opened them up just in time, or shall l say the head failed in time because I don't think I would have done it. Luckily the journals are still perfect. The rod bearings normally work much harder than the mains and if you can remember, they went through a couple of races with the oil temp off the scale at 150+ degrees. Luckily they are the new ones that arrived. The bottom end is almost complete except for the sump and flywheel. Just for curiosity, I checked the cam timing which is still spot-on.
A photo of the journal.
These are the bottom halves that go into the rod cap.
These are the top ones in the rod itself. Well worn and about to let go.
I haven't had a timing chain tensioner yet that lasted. Every time that I open the motor the tensioner's "hook" that holds the rubber part has broken off. I have already welded it once and that split took a small bit of metal with it when it broke. That means that it wasn't bad welding but maybe a lot of tensioning and slacking by the chain as the followers go over the lumpy cam at idling. I believe that when the engine is revving high, that slack side of the chain will be more constant than at idle speed. I had to weld it again.
So, the old wet-sump engine is almost ready to go, but the dry-sump is still waiting for the head which had a lot more work to be done. It doesn't look like I'll have it this year.
Regards, Frans.
The head has been skimmed and it is now a respectable 12.18:1 compression ratio. I have checked the spring tensions and there is no difference in pressure than the last rebuild. I thought that I had to do it because of the different head. The head is now assembled and waiting to be fitted after I'm finished with the bottom end.
I ordered rod and main bearings a while ago but only the rod bearings arrived. After removal and checking the mains, they can and will be re-used because I can't wait any longer. They are however in pristine condition.
That cannot be said about the rod bearings. I have opened them up just in time, or shall l say the head failed in time because I don't think I would have done it. Luckily the journals are still perfect. The rod bearings normally work much harder than the mains and if you can remember, they went through a couple of races with the oil temp off the scale at 150+ degrees. Luckily they are the new ones that arrived. The bottom end is almost complete except for the sump and flywheel. Just for curiosity, I checked the cam timing which is still spot-on.
A photo of the journal.
These are the bottom halves that go into the rod cap.
These are the top ones in the rod itself. Well worn and about to let go.
I haven't had a timing chain tensioner yet that lasted. Every time that I open the motor the tensioner's "hook" that holds the rubber part has broken off. I have already welded it once and that split took a small bit of metal with it when it broke. That means that it wasn't bad welding but maybe a lot of tensioning and slacking by the chain as the followers go over the lumpy cam at idling. I believe that when the engine is revving high, that slack side of the chain will be more constant than at idle speed. I had to weld it again.
So, the old wet-sump engine is almost ready to go, but the dry-sump is still waiting for the head which had a lot more work to be done. It doesn't look like I'll have it this year.
Regards, Frans.
That thing doesn't look like wear on the bearings. To my eye, that screams ripped welds.
Hi Frans
Yea those bearing shells are suffering fatigue failure in the bearing metal. Or put less scientifically "hey Frans give us a break with the heavy work"
Possibly a harder bearing might be worth considering if available !
Jaahn
Yea those bearing shells are suffering fatigue failure in the bearing metal. Or put less scientifically "hey Frans give us a break with the heavy work"
Possibly a harder bearing might be worth considering if available !
Jaahn
That kind of damage is very similar to what I see when a milling (or lathe) cutter welds itself to certain aluminium alloys. Using coolant (or a different cutter, or feed/speed or a combination of all of the above) makes it go away, but all of these are just measures to reduce temperature. I think an oil cooler would go a long way to mitigating the effects of pushing the engine hard. There hasn't been contact between the crank and bearing yet but it's not far. I would say the oil pressure was very good and that saved the engine so far but I agree with Frans. Lucky you took the engine apart.
Now that is so typical Murphy. The mains arrived about an hour after I fitted the sump!!!
Angelo, I am sure that it was a factor. The oil got so hot lately that the temp was somewhere over 150 because that is how far the gauge goes. In one of the videos, you can see that on the last lap the pressure dropped to about 10psi or there about. I have never had starvation due to aeration. That normally destroys the engine instantly. I have in the meantime done quite a bit on the cooling side with great success.
But as SZ said mentioned, I had some luck on my side by stripping the engine in time.
Regards, Frans.
Angelo, I am sure that it was a factor. The oil got so hot lately that the temp was somewhere over 150 because that is how far the gauge goes. In one of the videos, you can see that on the last lap the pressure dropped to about 10psi or there about. I have never had starvation due to aeration. That normally destroys the engine instantly. I have in the meantime done quite a bit on the cooling side with great success.
But as SZ said mentioned, I had some luck on my side by stripping the engine in time.
Regards, Frans.
Murphy is alive and well but certainly not looking at your big ends!! Those conrod bearings are quite a sight! You must use good oil Frans.
Lucky, lucky, lucky.........
Sorry Ray, I never saw the question. It is 55 psi up to 145 degrees, 60 psi when it drops down to 130 degrees.
I have just fitted the old engine with its new head and I will start it tomorrow. So holding thumbs that it is back to normal reliability like in the past. The old head had one valve guide that was fitted at a different angle as the others, it was lying visibly further out towards the outside, but they are all in line with this head
. That is a plus for me although I never had issues with the other skew valve.
I won't drive it yet as I will need a new Warrant of Fitness and that I can only get next week.
Regards, Frans.
I have just fitted the old engine with its new head and I will start it tomorrow. So holding thumbs that it is back to normal reliability like in the past. The old head had one valve guide that was fitted at a different angle as the others, it was lying visibly further out towards the outside, but they are all in line with this head
. That is a plus for me although I never had issues with the other skew valve.I won't drive it yet as I will need a new Warrant of Fitness and that I can only get next week.
Regards, Frans.
Oil temp in Celsius I presume? That's so interesting, for me at least. Mine has run 60 psi at 3000 rpm at normal water temperatures forever. If it gets over 90 degrees (water not oil) it drops a wee bit below 60. Never idles below 22-25 psi regardless of temperature. 360,000 km and one set of new bearings in 1988.Sorry Ray, I never saw the question. It is 55 psi up to 145 degrees, 60 psi when it drops down to 130 degrees.
I have just fitted the old engine with its new head and I will start it tomorrow. So holding thumbs that it is back to normal reliability like in the past. The old head had one valve guide that was fitted at a different angle as the others, it was lying visibly further out towards the outside, but they are all in line with this head
I won't drive it yet as I will need a new Warrant of Fitness and that I can only get next week.
Regards, Frans.
Best wishes to you and yours for 2022 Frans.
And the best to you guys as well John.
Yes, that is Celsius. I had the same oil pressure as you on the Matra down to the South Island and back, but that was with an oil temp of 100 -110 degrees all the way running around 4k rpm. When the race car's temp exceeded the gauge's scale of 150 + the oil press dropped drastically. It could have gone to 180 deg who knows. That is surely the reason for the condition of those big-ends. I have recently changed to the thickest full Synthetic oil, Penrite. It was running on Mineral oil for the last 9 of 12 years.
I have made the scoop under the body to catch air and force it through the oil cooler that helped the temp to stay around 140 -145 deg. That maintained the oil press very well. I have now added 2 x 12V server fans, those that sound like a helicopter taking off, in the ducting and incorporated their switching into the onboard PLC so that they stay off with normal driving and activate as soon as we start racing, all automatically. That is an inverted/opposite operation of the alternator that runs during normal driving and turns off when racing. Because I use a small 18 Ah battery I did a test with the battery and ran the fans for about 20 minutes with no substantial voltage drop. This is yet to be tested.
I started the new-head engine on the 31st and it sounded as good and crisp as always. Johan and I decided to go to a Playday first before we enter a full race day. Our racing season is buggered in any case because of the lockdown and the first race is in Taupo, 800 km return. I wouldn't like to test the engine so far away.
I will let you know how it went at the test.
Regards, Frans.
Yes, that is Celsius. I had the same oil pressure as you on the Matra down to the South Island and back, but that was with an oil temp of 100 -110 degrees all the way running around 4k rpm. When the race car's temp exceeded the gauge's scale of 150 + the oil press dropped drastically. It could have gone to 180 deg who knows. That is surely the reason for the condition of those big-ends. I have recently changed to the thickest full Synthetic oil, Penrite. It was running on Mineral oil for the last 9 of 12 years.
I have made the scoop under the body to catch air and force it through the oil cooler that helped the temp to stay around 140 -145 deg. That maintained the oil press very well. I have now added 2 x 12V server fans, those that sound like a helicopter taking off, in the ducting and incorporated their switching into the onboard PLC so that they stay off with normal driving and activate as soon as we start racing, all automatically. That is an inverted/opposite operation of the alternator that runs during normal driving and turns off when racing. Because I use a small 18 Ah battery I did a test with the battery and ran the fans for about 20 minutes with no substantial voltage drop. This is yet to be tested.
I started the new-head engine on the 31st and it sounded as good and crisp as always. Johan and I decided to go to a Playday first before we enter a full race day. Our racing season is buggered in any case because of the lockdown and the first race is in Taupo, 800 km return. I wouldn't like to test the engine so far away.
I will let you know how it went at the test.
Regards, Frans.
Sounds good Frans! I've often wondered what my oil temperature is. After a hot run here, the coolant is around 90 degrees and the oil hotter than usual - must be hotter because there's a threshold of some sort where idle speed oil pressure fluctuates rapidly in the 20-25 psi range rather than being fairly steady at its usual 24-26 psi. I use Penrite 20-60 mineral oil (the one with "full zinc"). Hardly racing conditions of course!
I reckon server fans are a great idea.
Do you remember the oil cooler on the 1950s Talbot-Lago GP cars? Tubular thing on top of the bodywork directly in the airflow.
Best wishes
John,
Your oil temp will fluctuate between 95 and 110 C. The Matra does have an oil temp gauge and down to the South Island, it crept up to 110 C on steep mountain passes. Other than that it remained at 100 C. The Matra's cooling system is good because you can't even provoke it to overheat.
My Skoda Fabia company car's oil temp remains at 95 C and on steep hills, it goes up to 104 C. It has a digital readout.
Frans.
Your oil temp will fluctuate between 95 and 110 C. The Matra does have an oil temp gauge and down to the South Island, it crept up to 110 C on steep mountain passes. Other than that it remained at 100 C. The Matra's cooling system is good because you can't even provoke it to overheat.
My Skoda Fabia company car's oil temp remains at 95 C and on steep hills, it goes up to 104 C. It has a digital readout.
Frans.