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Esprit Turbo project car - part3 - the further continuation


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Something else really needs to be clarified. There are book tolerances for parts. Measuring is tricky and there are serval errors that can affect readings. I have found even though a part may be in spec its performance may not be perfect. This is really where you gain by knowing this engine. The specialists can examine parts and instantly know when its toast or reusable. Thats why a specialist checked over all of my parts on the previous build before I assembled the engine and why I have done exactly the same this time. Unfortunately last time they were ok and this time they were not.

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On 16/02/2020 at 16:01, 910Esprit said:

Venolia - an American brand.    The slight variation being that they are oversised that allowed them to be used in rebored original liners.   As mentioned, now at 40k miles in engine running at upto 10psi with HC compression (and an HC head)

Whats the difference on an HC head? Im pretty sure the two Professional Mahle piston builds are using the standard LC head.

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3 hours ago, Lotusfab said:

Well my engine is currently being worked on by the professionals. Because of the three failures I am obsessed with metal fatigue. This engine is effectively new. Heres why from the top down! 

two replacement camshafts and cam carriers.

new steel cam followers

New cylinder head studs

cylinder head professional rebuild, new guides, inlet and exhaust valves.

new collets.

 good used Mahle pistons

 new piston rings

new big end bolts

crankshaft regrind to 10 thou,

new thrust bearings.

New main bearings

New big end bearings.

New steel liners

professional liner install, ring gapping and piston installation.

new replacement auxillery housing, new oil pump annulus and Rotor.

Im thinking about replacing the tensioner, but this might lead to new pulleys and a round tooth cam belt!

If I finished this build I will be just bolting it together and shiming the valves, which I have already done before. The shimming and sealing on my previous build were as good as any professional job. My issue now is time and whether I have enough to complete the job with all my other comitments.

The automatic tensioner is a concern. I replaced the springs and tensioned it perfectly using the correct procedure and with the correct Lotus guage. I would say when I took the engine apart the tension on the belt had reduced! If this system is used again the belt tension must be watched carefully! 

 

 

Oh and add

4 new round tooth pulleys

New round tooth cambelt 

A fixed belt tensioner.

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Inlet ports are larger.  Water stub at front is smaller (but can be swapped).   Ideally you should replace the inlet manifold etc, but I got good results from  simply opening up an LC manifold to blend with the larger ports.   I'm running larger main jets in DHLA40s  LC carbs, which actually have a larger venturi that correct HC DHLA45s.  Although lacking the 'power' jets fitted to the DHLA45s

Edited by 910Esprit
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2 hours ago, 910Esprit said:

Inlet ports are larger.  Water stub at front is smaller (but can be swapped).   Ideally you should replace the inlet manifold etc, but I got good results from  simply opening up an LC manifold to blend with the larger ports.   I'm running larger main jets in DHLA40s  LC carbs, which actually have a larger venturi that correct HC DHLA45s.  Although lacking the 'power' jets fitted to the DHLA45s

Interesting you have  made so many mods. I have been told my two specialists that no mods to the engine are required to operate with the Mahle pistons. The reson is the gasket. The original gasket was 1 mm thick. The HC compression is 10 PSI more per cylinder. The Goetze gasket is 1.7 mm thick. This extra thickness results in the compression ratio being reduced back to the LC ratio. I will measure the compression before the engine is run to confirm this is correct.

45 minutes ago, Steven162 said:

Are the professionals fitting the head?

Not sure yet, I may do it.

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Another feature of the Venolia pistons was that the spec compensated for for the reduced compression of the Goetze gasket!   All the mods are just about giving the car some extra 'go' but within the acceptable limits of a carburated turbo.   As mentioned ealier, I've done 40K in this config, so I guess its OK.   There is also an Alunox manifold on it too....

I assume your advice is correct. but bear in mind that Mahle pistons in Nickasil liners run a much closer tolerance than LC pistons do in  standard iron liners.  (IIRC its something like 2thou vs 6thou)    TBH I've never checked whether the liner ID or the piston OD accounts for the clearance reduction.

 

 

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Having researched it I think the cam belt must be converted to round tooth. With so much invested I cant risk tooth slip. Its also a major step forward to,replace the tensioner, especially as my HC block is designed for it already. I am also upgrading the needle bearing. In the end of the crank, I never liked that bearing even though I renewed it. 

To upgrade to round tooth you need three pulley wheels and the crankshaft one. The fixed tensioner parts are all available new from S and J. Talking to the experts the three biggest issues on the engine are the adjustable tensioner, square tooth belt and the pistons. Replacing all of these hopefully will result in a very robust power plant. IMG_0976.thumb.PNG.27893f5eea9d7496b7357e41b08c4210.PNGIMG_0981.thumb.PNG.42190fe128c0e18ac3fbd4508b5be683.PNG

I wont flower it up its very annoying what has happened but I think I'm heading for a far improved engine.

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1 hour ago, Lotusfab said:

Heres why I switched outbthe exhaust valves for solid ones. This engine rebuild series is well worth a watch! Of course they dont have the complicated Lotus oil pump, but theres a lot more engine! 


Really? That’s a completely different engine, with completely different valves, which had a specific issue with its sodium-filled valves at that time which, but the way, had much larger valve heads.

In my opinion, if the valves measured up within spec, you’re throwing the baby out with the bathwater, but hey-ho.

Margate Exotics.

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1 hour ago, Chillidoggy said:


Really? That’s a completely different engine, with completely different valves, which had a specific issue with its sodium-filled valves at that time which, but the way, had much larger valve heads.

In my opinion, if the valves measured up within spec, you’re throwing the baby out with the bathwater, but hey-ho.

Some of the valves were worn. I posted it for the valve construction info and interest only. Its nothing to do with the engine. The fact is new solid valves are very unlikely to fail compared with worn 40 year old ones that have suffered more than one mechanical failure. Im not convinced any of the new replacements are sodium filled having heard of a sodium valve that was cut in half and found to be solid, in the case they were bought for the Cosworth! But you have to make that choice yourself when replacing them. You can get second hand ones, but then you dont know what life they have had. My only reservation with solid was the temperature they will operate at, but that has already been tested by the experts who tell me its not an issue. So new valves it is. If they dont live up to expectations I will let everyone know.

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You posted that video up saying its content was the reason you will be fitting solid-stem valves. Now you’re saying it’s because some of your valves are worn, and it’s nothing to do with your engine. Make your mind up, because some people will be incorrectly influenced by what you posted.

I watched that video some time ago, and, probably like many other professional engineers, winced because whilst Tyrell may be a clever bloke, he doesn’t make it clear enough that the issue was not with sodium-filled valves per se, just with the Lamborghini V12 engine. Frankly, posting it on this thread was a waste of time unless you have one of those engines, which you don’t, and by your own admission your engine is unrelated. It should have gone into the general pics and videos section, not here.

Sodium-filled valves have been around a very long time, and have very good heat-dissipation qualities which the majority of solid stem valves cannot match. I’ve worked professionally with both types over many years, and in my experience, I’ve never seen a single sodium-filled valve fail. If you can find me one that’s failed in a 910 engine that hasn’t been due to timing problems, I’ll be surprised, and willing to be proven wrong.

 

Margate Exotics.

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5 minutes ago, Chillidoggy said:

You posted that video up saying its content was the reason you will be fitting solid-stem valves. Now you’re saying it’s because some of your valves are worn, and it’s nothing to do with your engine. Make your mind up, because some people will be incorrectly influenced by what you posted.

I watched that video some time ago, and, probably like many other professional engineers, winced because whilst Tyrell may be a clever bloke, he doesn’t make it clear enough that the issue was not with sodium-filled valves per se, just with the Lamborghini V12 engine. Frankly, posting it on this thread was a waste of time unless you have one of those engines, which you don’t, and by your own admission your engine is unrelated. It should have gone into the general pics and videos section, not here.

Sodium-filled valves have been around a very long time, and have very good heat-dissipation qualities which the majority of solid stem valves cannot match. I’ve worked professionally with both types over many years, and in my experience, I’ve never seen a single sodium-filled valve fail. If you can find me one that’s failed in a 910 engine that hasn’t been due to timing problems, I’ll be surprised, and willing to be proven wrong.

 

The bit in the video I was reffering to was the description of the sodium valves. The fact they are hollow and the weak point is around the head. I hadnt considered switching to solid valves until it was first mentioned by a well know restorer and expert that always replaces all the valves when they build an engine. The video is just for entertainment. As Ive said countless times do not  replicate anything on here and if you do so its at your own risk. Everything here is for entertainment and my own view. I thought it was a really good video!

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40 minutes ago, Lotusfab said:

 

The bit in the video I was reffering to was the description of the sodium valves.  I hadnt considered switching to solid valves until it was first mentioned by a well know restorer and expert that always replaces all the valves when they build an engine. The video is just for entertainment. As Ive said countless times do not  replicate anything on here and if you do so its at your own risk. Everything here is for entertainment and my own view. I thought it was a really good video!

 

My point here, which you seem to be doing your level best to avoid, is that you are making sodium-filled valves (fitted as standard in most of the later Lotus 900 series engines) sound to TLF members as though they're devil's own work. They are not, and in fact they are superior in this case due to their longevity and better heat-transfer properties.

By way of an example, the valves in my S4s cylinder head have been cleaned, are all within tolerance and will be refitted. This is after covering 75,000 miles, and with both sets of valve guides knackered. No drama, no heads falling off, they just work.

I'm out.

 

 

 

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Margate Exotics.

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