Esprit Turbo project car - part3 - the further continuation

[Andyww]

1 hour ago, andydclements said:

Those are the verier pulleys, the "vernier" refers to a way the scales for readings are set, just like a vernier gauge.

Ah OK.

I was thinking of the pulleys which are fitted as standard on Ferrari engines which have a vernier adjustment using dowels placed in vernier holes like this

 

[CHANGES]

14 minutes ago, ekwan said:

If you are running a standard camshaft, there is not a lot to be gained by tweaking the camshaft timing. So I would see this as an unnecessary expense. You would need to pay for the pulleys, cost of an engine tuner, and rental of a rolling road to set all this up properly............just to gain 3-5BHP.

I am running standard cam shafts....  I have tweaked the timing ... and i went to the expense of buying the pulleys and renting the dyno for a day ,  BUT ..  along with a few other little mods.. I only initially gained ... 147 BHP  .... Later on we took that to up to 197 extra bhp with a few more mods .. 

But you don't need a dyno to set up to engine design timing , the link above and a bit of capability will do that  ...   And it does make a difference , you may not feel it but your engine will know it .. 

[ekwan]

2 minutes ago, CHANGES said:

This statement is so wrong..  By skimming the head you reduce the distance between the cam and crank pulley's so the cam timing changes..  Lotus used to provide oversize head gaskets to compensate for skimming of the head , giving guide lines on what to skim off to stay withing the given cam timing set ups..   This is why people believe when you go outside what is recommended the head is scrap..  utter rubbish,..  The adjustable pulley's  compensate for the skimming now only one gasket is available . regardless of how much you need to skim.  

Isn't the use of different gaskets after skimming to compensate for the reduced head thickness and to raise the compression ratio again, which of course, is more critical in an older turbocharged car that doesn't have a knock sensor? The relative rotational positions of the camshafts, relative to the cam pulleys remain unchanged. Also, there is a limit a head can be skimmed for various reasons......first being physical contact between valves and pistons, second being the fire ring of the cylinder gasket no longer offers effective sealing.

You are absolutely correct in saying that the physical distance between the crank and cam pulleys change after skimming. But this is a linear measurement. We are worried about rotation measurements that don't change. 

[Andyww]

25 minutes ago, ekwan said:

1. I had the impression that Lotus replaced the trapezoid belt with the rounded to comply with CA regulations that require the belts to run for at least 100,000 miles as part of the revised emission regulations. Yes, the rounded tooth belts will last out the 100,000 miles if that's the case, but then the trapezoid belts and tensioners will last out right through the recommended replacement intervals.

 

 

I remember back in the day when this was all happening and Mike Walters, the ex-Lotus guy who was Club Lotus tech guy would talk about it.

It is true that the main reason the round tooth belt was introduced was belt life and they even did a test of lifetime. But back before that they did have jumping teeth on the Jensen-supplied engines which resulted in massively expensive warranty claims. This mainly happened in very cold climates at startup. So they designed the spring tensioner and also added some extra belt snubbers. I cant remember which came first but I recall they had to have various tries at it before they eliminated the problem. The introduction of the round tooth belt and the 100,000 mile test they did confirmed they could go back to the fixed tensioner.

[ekwan]

10 minutes ago, CHANGES said:

I am running standard cam shafts....  I have tweaked the timing ... and i went to the expense of buying the pulleys and renting the dyno for a day ,  BUT ..  along with a few other little mods.. I only initially gained ... 147 BHP  .... Later on we took that to up to 197 extra bhp with a few more mods ..     

So did I. I did a few mods on my Lotus Elise S1, tweaked it on a dyno and went from 118 to 320 BHP. But it was just a "few" mods 🤣

[Andyww]

6 minutes ago, ekwan said:

 

You are absolutely correct in saying that the physical distance between the crank and cam pulleys change after skimming. But this is a linear measurement. We are worried about rotation measurements that don't change. 

That would only apply if the belt length either side of the pulley were the same which its not though. The belt run is much longer on one side than the other.

[ekwan]

1 minute ago, Andyww said:

I remember back in the day when this was all happening and Mike Walters, the ex-Lotus guy who was Club Lotus tech guy would talk about it.

It is true that the main reason the round tooth belt was introduced was belt life and they even did a test of lifetime. But back before that they did have jumping teeth on the Jensen-supplied engines which resulted in massively expensive warranty claims. This mainly happened in very cold climates at startup. So they designed the spring tensioner and also added some extra belt snubbers. I cant remember which came first but I recall they had to have various tries at it before they eliminated the problem. The introduction of the round tooth belt and the 100,000 mile test they did confirmed they could go back to the fixed tensioner.

I was working at FoMoCo as an engine designer. We were designing the CVH engines in the early-mid 1980s when the instruction came in to specify 100,000 mile belts due to pending regulatory issues in CA beginning year 1990.

[CHANGES]

15 minutes ago, ekwan said:

You are absolutely correct in saying that the physical distance between the crank and cam pulleys change after skimming. But this is a linear measurement. We are worried about rotation measurements that don't change. 

As the gap between the exhaust cam pulley and the crank pulley reduce ,you get a rotational effect on said pulley's because the belt is a constant..  

15 minutes ago, ekwan said:

Isn't the use of different gaskets after skimming to compensate for the reduced head thickness and to raise the compression ratio again, which of course, is more critical in an older turbocharged car that doesn't have a knock sensor?

It does compensate for CR change at the same time , but if needed that can be altered and facilitate for in other ways when only the one thickness of gasket is available and outside the tolerance .

 

15 minutes ago, ekwan said:

Also, there is a limit a head can be skimmed for various reasons......first being physical contact between valves and pistons, second being the fire ring of the cylinder gasket no longer offers effective sealing.

There is always a limit , but i have gone .055 without issue ... Different set up and piston design may need measurements to make sure , but that is all part of engine building .... when changing any one thing ... Check check check again..  

Not sure why you would think the fire ring would be less effective at sealing . The clamping process is the same .  

[ekwan]

2 minutes ago, CHANGES said:

As the gap between the exhaust cam pulley and the crank pulley reduce ,you get a rotational effect on said pulley's because the belt is a constant..  

It does compensate for CR change at the same time , but if needed that can be altered and facilitate for in other ways when only the one thickness of gasket is available and outside the tolerance .

 

There is always a limit , but i have gone .055 without issue ... Different set up and piston design may need measurements to make sure , but that is all part of engine building .... when changing any one thing ... Check check check again..   

Don't people need to sleep??? 🤣

Yes. As engine builders, there are a host of things can do from an engineering aspect.........machine deeper valve pockets, shim head gaskets, skim off piston crowns, enlarge combustion chambers, lower boost pressures, retard ignition timing etc. Each to his own.

[ekwan]

24 minutes ago, Andyww said:

Ah OK.

I was thinking of the pulleys which are fitted as standard on Ferrari engines which have a vernier adjustment using dowels placed in vernier holes like this

 

The very old Alfa Romeo engines used on the 105 series cars had no crankshaft or camshaft markings. You timed them in using a dial gauge and a special tool. And neither do the latest Range Rover diesel engines either.

[andydclements]

16 minutes ago, Andyww said:

Ah OK.

I was thinking of the pulleys which are fitted as standard on Ferrari engines which have a vernier adjustment using dowels placed in vernier holes like this

 

Ah, yes understandable. I'm also sure that if you went to ebay or similar you'd find "Digital vernier gauges" , which those things are not, but people have become less understanding of how a verier scale works and so think of verier as a style of an item.

Dave @CHANGES has already shown his engine with those sprockets, but if every you want to think about the ability of those fixings, think of the flywheel (where a lot more torque is applied than these), that tiny little c6mm dowel isn't what stops the surfaces slipping, it's the friction due to the bolts, so the bolts on the pulleys should be fine.

[CHANGES]

13 minutes ago, ekwan said:

yes. As engine builders, there are a host of things can do from an engineering aspect.........machine deeper valve pockets, shim head gaskets, skim off piston crowns, enlarge combustion chambers, lower boost pressures, retard ignition timing etc. Each to his own.

So if you know all of this , why did you make the statement......

56 minutes ago, ekwan said:

3. Skimming the head changes nought as far as the TDC position is concerned. TDC refers to the position of the piston at the top of it travel, usually no. 1 & 4 pistons. As for the camshaft pulleys, no changes either. You still time them in using the original markings. Yes, the use of vernier pulleys may allow you to time in the camshafts more accurately, but this is merely taking care of production tolerances during the camshaft grinding process, and nothing more. 

All it did was confuse those who are not fully in touch with the technicalities of engine building , and waste my time sending bloody replies to correct such twaddle...    If you know better you should not mislead the readership with statements like that...   People read these forums to find out more not get false leads ...   I give up...       

[ekwan]

15 minutes ago, CHANGES said:

So if you know all of this , why did you make the statement......

All it did was confuse those who are not fully in touch with the technicalities of engine building , and waste my time sending bloody replies to correct such twaddle...    If you know better you should not mislead the readership with statements like that...   People read these forums to find out more not get false leads ...   I give up...       

Because we are re-building a standard engine, not modding them. The gist of my statements.......remove then reassemble the way you found it.

Edited February 27, 2020 by ekwan

[CHANGES]

23 minutes ago, ekwan said:

Because we are re-building a standard engine, not modding them. The jist of my statements.......remove then reassemble the way you found it.

OK ... Firstly you state '' quote '' re-building a standard engine..   Not reassembling .. when you re build , you need to machine surfaces and change parts etc etc..  because of this you can not reassemble the way you found it..       If you remove strip and reassemble an engine ... all you do is repeat what you had, same failings, same worn / faulty parts...  This is what @Lotusfab  found with his PRV.. admittedly he did not fully strip but you get the idea... a fault was repeated.  

In my book it make no different standard or modded , A physical dimension on an engine should be as close as possible to perfect....   When an engine is rebuilt or reassembled you should measure the cam timing regardless... In most cases it will be out and adjustable pulley's are the answer....  You don't have to fit them , you can run sub standard engine , but readers do have the right to know that there is an alternative and it does make a difference ..Especially on older engines where parameters get changed....   its all about maintaining a standard...      Understanding what is available , what has been done and why, is how people move forward..   

I shall not say anymore on this subject unless asked . it is Fabians thread not a debate forum..     

[Lotusfab]

7 hours ago, CHANGES said:

OK ... Firstly you state '' quote '' re-building a standard engine..   Not reassembling .. when you re build , you need to machine surfaces and change parts etc etc..  because of this you can not reassemble the way you found it..       If you remove strip and reassemble an engine ... all you do is repeat what you had, same failings, same worn / faulty parts...  This is what @Lotusfab  found with his PRV.. admittedly he did not fully strip but you get the idea... a fault was repeated.  

In my book it make no different standard or modded , A physical dimension on an engine should be as close as possible to perfect....   When an engine is rebuilt or reassembled you should measure the cam timing regardless... In most cases it will be out and adjustable pulley's are the answer....  You don't have to fit them , you can run sub standard engine , but readers do have the right to know that there is an alternative and it does make a difference ..Especially on older engines where parameters get changed....   its all about maintaining a standard...      Understanding what is available , what has been done and why, is how people move forward..   

I shall not say anymore on this subject unless asked . it is Fabians thread not a debate forum..     

HinDave, have you written an engine build book? If so please can you post a refernce. Thanks.

[Lotusfab]

I have  been trying to sort issues on the head and engine today. I can now with 99  percent confidence explain why my engine failed. The scoring was caused buy blast residue left over from bead blasting which was logged in the cam covers. I cleaned them but the media was released when the engine got hot. This media cause all of the upper cam and follower scoring. I know because like all these things it has happened before on four other engines I know of!  None of the failure was due to aqua blasting. The rest of the wear was caused by the sticking PRV. 

This build I am leaving nothing to chance. I measured the free length of the springs almost all of them were out of spec. Some of the  inlet collets were pretty worn. I have managed to get excellent replacements. I am convinced its a very good move to replace all of the valves. The exhaust valves I am using are made of a modern material with excellent heat transfer properties. The inlet and exhaust faces of the head are being machined then it will be skimmed and helicoils fitted. Oversized guides will be fitted throughout.

I have now got the fixed  tensioner, bracket, round tooth pulleys and crank pulleys. The teeth are a lot depper than the square tooth belt, which is probably why it doesnt slip.  Now just need to wait until all the machining is complete and then reassembly can take place. 

[Barrykearley]

Cam covers? Or cam towers?

the cam covers really haven’t got anywhere for grit to hide.

[Lotusfab]

Definately, cam covers..The blasting grit gets stuck in them and cleaning other than vapour blasting doesn't get it out. When the engine heats up its released. Lesson is do not powder coat blast on any interior surfaces. Aqua blasting is fine if followed with  washing. I will now have to get the cam covers aqua blasted and then washed to ensure theres no more media stuck in them! I have a weld repair in one which is ideal for bits to stick in! 

[drdoom]

10 hours ago, Lotusfab said:

Definately, cam covers..The blasting grit gets stuck in them and cleaning other than vapour blasting doesn't get it out. When the engine heats up its released. Lesson is do not powder coat blast on any interior surfaces. Aqua blasting is fine if followed with  washing. I will now have to get the cam covers aqua blasted and then washed to ensure theres no more media stuck in them! I have a weld repair in one which is ideal for bits to stick in! 

. . . just as I had advised, Fabian you're on the right track in my opinion.

[Andyww]

This is probably not helped by the fact the Lotus castings of the day were not very good, they were a typical 80's British motor industry product. They have a rough surface and they had problems with porous castings sometimes.

[CHANGES]

12 hours ago, Lotusfab said:

Definately, cam covers..The blasting grit gets stuck in them and cleaning other than vapour blasting doesn't get it out. When the engine heats up its released. Lesson is do not powder coat blast on any interior surfaces. Aqua blasting is fine if followed with  washing. I will now have to get the cam covers aqua blasted and then washed to ensure theres no more media stuck in them! I have a weld repair in one which is ideal for bits to stick in! 

 

2 hours ago, drdoom said:

. . . just as I had advised, Fabian you're on the right track in my opinion.

Not convinced by this .....  I understand the reasoning but not the Logic..    

Lets just say you had some media lodged in the cam covers that had not washed out on all the clean ups you did..  Its then released  when the engine got hot...    Its path will be to flow with the oil into the sump.  From there it will go into the oil pick up and pump inc the PRV.,.   From there to the cooler and filter... Journeys end ...   It could not get into the main oil gallery to grind away at those cam bearings and other parts as indicated..    You have to realise these bearings are at the ends of the oil run and the oil is under pressure within these. There is no way any  media could go against the pressure flow..    Any media that was left in any part up stream of the filter then yes,  but to do the damage it did it will need to have been on the lines of aluminium oxide.. so unlikely again..      All the damage you have shown is what we would expect to see with the engine running dry .. once this damage was done ,  then it was a slippery slope to eventual failure..  I expect the initial start up and lack of primed oil pressure for far to long was the primary cause..  It was as you stated escalated by a stuck PRV.  This may have been caused by ingress of media from the source you mention , But looking at the PRV pic you posted , there was an obvious previous issue within that area which had been overlooked.. So as to the reason it stuck this time being the last build or a previous oversight not being picked up on, will be a matter of conjecture.       I feel you must now put the causes behind you . It serves no purpose to look for a scapegoat..  concentrate on assembly with knowledge gained , most importantly prime the engine prior to starting and monitor closely during break in period.. 

 

[Lotusfab]

I posted this so others dont fall foul of the same problem. The  four newly rebuilt engines I mentioned  all failed completely due to cam cover contamination and needed complete rebuilds. My case is different because the PRV was also unfit for service. These other engines all had perfect oil punps. The grit got into the cam follower areas and like mine resulted in the skirts wearing away and then failure. Somehow this lead to total engine failure. Mine seemed to have oil that was more like grinding paste than oil.  This is exactly what happened to my cam followers! Although, other damage I think was definately due to the PRV and oil pressure issues. 

I agree nothing more to gain from further discussion. All efforts must now be applied to constructing a robust Turbo Esprit engine. 

The machining work is going  to take longer than I had hoped, but you cannot rush any of this, it takes how long it takes. The head is being rebuilt as previuosly described. Im rebuilding the new  auxillery housing. The shaft is removed. Im cleaning up the bearing surfaces and then it will get a new rotor, annulus and seal. I will remove the PRV and examine for scoring and action in the sleeve. When Im happy it will all be put back together. I found slight distortion in the pickup pipe neck. So it has been replaced with a brand new one, wire gauze etc from S and J. 

I will check the spec of the pump again then  it gets packed with graphogen. I'll do what Barry sugested  and test it on the stand pumping at least 1/2 litre of oil out with a power drill turning the rotor. I'll put some pumping figures on here to help anyone else whos doing a build.

[Barrykearley]

2 hours ago, Lotusfab said:

I'll do what Barry sugested  and test it on the stand pumping at least 1/2 litre of oil out with a power drill turning the rotor. I'll put some pumping figures on here to help anyone else whos doing a build.

Be very aware that the oil will drain back pretty damn quickly after you have done this. I tried to extract some from my oil to turbo supply pipe by turning over the car with the plugs out the day after I’d removed the turbo - nada - nowt - nothing. It drains back that fast. This is why the recommendation is to pack the pump with graphogen on build 

[CHANGES]

16 hours ago, Lotusfab said:

I posted this so others dont fall foul of the same problem. The  four newly rebuilt engines I mentioned  all failed completely due to cam cover contamination and needed complete rebuilds.

Just so all people building or buying rebuilt engines don't have a panic ...  I am sorry Fabian but I can not except this as a sweeping statement of fact...  Doing so would be remiss without any categorical evidence other than your statement..   For one I am sure if four newly built engines all failed as you say from contamination on cam covers needing complete rebuilds , then it would have been common knowledge on this forum ... and others ..  Also very remiss of the builder..     I can not help but feel here,  you have been fed false news which conveniently fits your agenda 

16 hours ago, Lotusfab said:

These other engines all had perfect oil pumps.

Statement of fact......   Any media that gets into an engines oil system always damages the oil pump ..  it is the single most unprotected part in the engine .  Its only filter protection is a gauze which only stops the larger particles ..  Anyone who builds engines that have failed always check the oil pump first ... its a useful indication of reason.  Any engine that has failed as you indicated will have damage on the oil pump.  

16 hours ago, Lotusfab said:

The grit got into the cam follower areas and like mine resulted in the skirts wearing away and then failure. Somehow this lead to total engine failure. Mine seemed to have oil that was more like grinding paste than oil.  

For your oil to be more like a grinding paste than oil , you would need a considerable amount of media .  It would need to be of a very aggressive type and become attached to the associated surface on mass.  To do this level of damage in and on the surface you mention , the media particles would need to be smaller than .0005'' just to get into that area and have any effect , also of harder material than the iron follower..  

16 hours ago, Lotusfab said:

This is exactly what happened to my cam followers!

OK lets just say,  you did not clean your cam covers and left them so contaminated that particles were in sufficient quantity and nature to eroded your cam followers to the point of detonation.     That still does not explain the camshaft bearings and all the other bearing surfaces than were worn out.  ..     

16 hours ago, Lotusfab said:

Although, other damage I think was definately due to the PRV and oil pressure issues. 

Now we get back to a more plausible reason..   Lack of oil and pressure ....   All the damage to your cam followers, cam shaft bearings and housings etc , will have been from the effect of a form of micro welding of the moving surfaces due to lack of lubrication. Once this has started it escalates quite quickly and introduction of oil after will only slow the eventual failure not stop it..   This form of contamination happens from within the friction surfaces ( un-lubricated contact area's )  , not from an outside media..  It does create its own media which then goes on to pollute other area's within the engine..    poor oil pressure from stuck or sticking PRV after would only compound the issue ...  When this sort of failure happens , it is not unusual to see sticking PRV . This is the result of metal parts from worn surfaces finding there way into the valve. ( as stated in previous post )..     

What we seem to keep coming back to is blaming something that there is very little evidence in this case to back up  ,                ( massive media contamination) . This is pure supposition  as apposed to a diagnosis based on other failures with same symptoms and results .. In the main these failures  were due to poor assembly , previously worn parts being refitted , but most commonly lack of oil/pressure...      You yourself admitted you ran the engine for some time with no oil pressure on initial start up ..   This is where you need to be focusing your attention.   I understand people like to divert the blame elsewhere,  not admitting it was their own procedures that was really at fault.  But when evidence points , you would be wise to consider.    

Fabian i only say this as you will be repeating the same faults over, if you blame media contamination and do not give credence to other areas on assembly and start up .. 

Please do not take this as a personal criticism, it is only mean't as a balanced observation on a public forum, nothing more than dialogue  .  Stay positive ,  Always here if needed ... 

 

[Lotusfab]

7 hours ago, CHANGES said:

Just so all people building or buying rebuilt engines don't have a panic ...  I am sorry Fabian but I can not except this as a sweeping statement of fact...  Doing so would be remiss without any categorical evidence other than your statement..   For one I am sure if four newly built engines all failed as you say from contamination on cam covers needing complete rebuilds , then it would have been common knowledge on this forum ... and others ..  Also very remiss of the builder..     I can not help but feel here,  you have been fed false news which conveniently fits your agenda 

Statement of fact......   Any media that gets into an engines oil system always damages the oil pump ..  it is the single most unprotected part in the engine .  Its only filter protection is a gauze which only stops the larger particles ..  Anyone who builds engines that have failed always check the oil pump first ... its a useful indication of reason.  Any engine that has failed as you indicated will have damage on the oil pump.  

For your oil to be more like a grinding paste than oil , you would need a considerable amount of media .  It would need to be of a very aggressive type and become attached to the associated surface on mass.  To do this level of damage in and on the surface you mention , the media particles would need to be smaller than .0005'' just to get into that area and have any effect , also of harder material than the iron follower..  

OK lets just say,  you did not clean your cam covers and left them so contaminated that particles were in sufficient quantity and nature to eroded your cam followers to the point of detonation.     That still does not explain the camshaft bearings and all the other bearing surfaces than were worn out.  ..     

Now we get back to a more plausible reason..   Lack of oil and pressure ....   All the damage to your cam followers, cam shaft bearings and housings etc , will have been from the effect of a form of micro welding of the moving surfaces due to lack of lubrication. Once this has started it escalates quite quickly and introduction of oil after will only slow the eventual failure not stop it..   This form of contamination happens from within the friction surfaces ( un-lubricated contact area's )  , not from an outside media..  It does create its own media which then goes on to pollute other area's within the engine..    poor oil pressure from stuck or sticking PRV after would only compound the issue ...  When this sort of failure happens , it is not unusual to see sticking PRV . This is the result of metal parts from worn surfaces finding there way into the valve. ( as stated in previous post )..     

What we seem to keep coming back to is blaming something that there is very little evidence in this case to back up  ,                ( massive media contamination) . This is pure supposition  as apposed to a diagnosis based on other failures with same symptoms and results .. In the main these failures  were due to poor assembly , previously worn parts being refitted , but most commonly lack of oil/pressure...      You yourself admitted you ran the engine for some time with no oil pressure on initial start up ..   This is where you need to be focusing your attention.   I understand people like to divert the blame elsewhere,  not admitting it was their own procedures that was really at fault.  But when evidence points , you would be wise to consider.    

Fabian i only say this as you will be repeating the same faults over, if you blame media contamination and do not give credence to other areas on assembly and start up .. 

Please do not take this as a personal criticism, it is only mean't as a balanced observation on a public forum, nothing more than dialogue  .  Stay positive ,  Always here if needed ... 

 

Hi Dave,

Thanks for comenting. I'm all for anything that helps me and other forum members to successfully rebuild. I won't coment publically any more about the four engines, but will tell you all about it privately if you wish. I thinkhere mentioned a wheeler dealers episode (I believe an Alfa Romeo) where they blast the Cam covers and the blaster meticulously masks the internal parts because of previous failures he experienced, someone may have a link? 

Anyhow, its a fact all four were rebuilt by an expert, all four failed and needed total rebuilds. The cause was the media logged in the cam covers - released at high temp. The cam follower damage description was Identical to mine. I agree the PRV was the main cause of damage in this case. So readers you decide, blast the cam cover internals with powder coat media, clean them with brake cleaner or Aqua blast and wash. I know what I will do this time! No more comments from me about the failure.

Think I was pretty unlucky really. If I had know about the removable PRV and not blasted the cam cover I would still have a servicable engine! I wont make those two mistakes again!