free hit
counters
Esprit Turbo project car - part3 - the further continuation - Page 234 - Esprit 'Project & Restoration' Room - The Lotus Forums Jump to content
Lotusfab

Esprit Turbo project car - part3 - the further continuation

Recommended Posts

Gearbox selector shaft

There were quite a few modifications to the gearbox pre and post C35. My original was pre C35. It had a different bolt on the 5 th gear synchro that allows oil through. The used box I bought is a C35. I could not pass up the opportunity to upgrade the gear selector. Not only was the used one corrosion free, but the spring used to centre the arm has been redesigned. It is smaller and weaker which means its easier to move the lever in and out of the box. The strong spring used in the older type was probably responsible for so many snapped gear levers. Its a big improvement which I look forward to testing. I have now checked all the gear changes and , as before, its all working perfectly. Now just waiting for the new output bearings to finish the build. 

  • Like 1

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

Forget these are you are in trouble! 2F42FD78-CE95-4C9E-A64D-BB0CEDC30EDF.thumb.png.ab9d803821f34f1b343d07833e414b9a.png

I’m taking it slowly and being extra pedantic. Lots of time off work now to get this done correctly without distraction. I think I prefer engine to gearbox work!

Share this post


Link to post
Share on other sites

It will be very Interesting to see how quickly this engine builds oil pressure from dry. The spec now for the pump and pick up pipe is as it left the factory. If it builds pressure easily the reason for all our oil pressure woes must be the pump or pick up pipe.

Share this post


Link to post
Share on other sites

The ultimate in Esprit heads?


British Ambassador to Florida, New York, Denmark and Newfoundland.  And Sweden.

Share this post


Link to post
Share on other sites
5 hours ago, Lotusfab said:

this is the ultimate in Esprit heads!

Looks very nice Fabian ,  ,  what extra's have you had done , other than change the valve material spec. ( so much can be done ,  it would be nice if you could list it all with photo's  ) ...   I  would also be interested on the chosen combustion chamber volume , looks like its had a good skim and valve seats cut back..   You will need to know this , along with your piston bowl volume , deck height and chosen head gasket squish size , to calculate you static compression ratio.  Especially as you have changed piston type and block as well .   When you have your static C/R  figures , you can then calculate your waste gate boost setting requirements to give the desired final C/R.   Otherwise you could be showing stock boost level but running much higher final C/R..   

2 hours ago, Lotusfab said:

Forget these are you are in trouble! 

I would also put a bit of thread sealer on those grub screws. 

Keep up the good work.. 

D   

 

  • Like 1

Share this post


Link to post
Share on other sites

Thanks Dave, I got a bit Enthusiastic and got carried away!  I haven’t done anything to increase power output. In fact Mike has a CNC head which is far superior in terms of power output and gas flow as I’m sure your ported heads are Dave. I think it gained 40 Hp! By ultimate spec I was really referring to all the upgrades - valves, helicoils, machining. I have nowhere near your understanding of engine design so have to try and keep it simple.
I plan to assemble and check the compression prior to running. If what I have been told is correct it should be the same compression as a stock Turbo when it left the factory with standard pistons. Why because the new gasket we alL use is thicker than the original. I know of two engines identical to this that have no issues running Mahle pistons. The compression on a standard Turbo is reduced. The upgraded pistons should bring it back to factory spec. I plan to check the compression prior to running the engine to confirm this is the case. 
Luckily I remembered to use loctite on the grub screws!
Giorgio has got me thinking about the oil pump test. From my research these type of rotor oil pumps generally don’t need priming. The problem comes because Lotus decided to mount the pump at a higher level than the oil reservoir. The pump will need to pump air first before the oil arrives. In order to pump gas there has to be a good seal. If there is no oil in there thats tricky. I have thought about this a lot after the previous disaster. I have packed the pump with graphogen. I am going to syringe oil directly into the housing through the oil feed to the head before I put the head back on. I will then do the pump test by pumping 1 litre of oil out through the Turbo feed line using a drill connected to the auxiliary pulley  . I will note the time It takes so there is a rough guide for anyone else attempting this.

  • Like 1

Share this post


Link to post
Share on other sites
10 hours ago, Lotusfab said:

I have packed the pump with graphogen. I am going to syringe oil directly into the housing through the oil feed to the head before I put the head back on. I will then do the pump test by pumping 1 litre of oil out through the Turbo feed line using a drill connected to the auxiliary pulley

John Douglas, AKA molemot, used to swear by spinning the auxiliary shaft with an electric drill until pressure was registered, obviously that was before fitting the drive belt. :thumbup: 


Cheers,

John W

http://jonwatkins.co.uk

Share this post


Link to post
Share on other sites

Hi Dave, thanks for pointing this out. I just spent some time this morning going through static compression ratio calcs with an expert. We made allowances for all of the components that were changed using figures they know from experience. The result was such they said  it was unnecessary to make any measurements.

However, It seems a simple matter to measure and calculate the static compression ratio, but it will add some time, which I am short of. I am considering whether to measure it. Knowing the static compression ratio how can you translate this to a boost pressure change? Will it be of any significance? I know the other two engines have no running issues so I am edging towards pressing on with the build.

Share this post


Link to post
Share on other sites

Actually I have all of the equipment needed to calculate the compression ratio, so I might as well get on with it! 

  • Like 2

Share this post


Link to post
Share on other sites

Finished the head assembly. I am working really hard now to sort this car! Tomorrow I will calculate the CR as Dave suggested. I have been trying to get manufacturer details on the Gasket, without much luck. I need the compressed thickness and Bore diameter. The are plenty of online calcs to assist. I will post the CR on here out of interest for anyone else considering Mahle pistons.E60AF923-5D2E-46F3-A82B-5C95F5450FAE.thumb.jpeg.f07ad88f6fe76993cd76ef14354d65a6.jpeg something is missing from the head, any ideas? 

06E0522D-E9A3-4A03-B8B2-3CAC17EE9C2A.jpeg

Share this post


Link to post
Share on other sites

Oil pump

I have learned the hard way with this. I asked an expert whats their take on it. Basically it doesn't require priming, you can pack with graphogen or similar. When its spun up with a drill there should be oil pressure quite quickly.  If their isn’t something is wrong. I will put this to the test and spin it up as is. I am 100 per cent confident the oil pump is now as new, so if it doesn't work I really will be stumped.

 

  • Like 2

Share this post


Link to post
Share on other sites

I’ve not packed mine - I will force prime it like i did last time. Remove oil feed to turbo and whack about 1/2 litre into the supply pipe with a pump.

remove spark plugs - remove crank sensor and turn it over until you get more than 1/2 litre out that same pipe. Job done. Let’s hope it works again this time 🤪

  • Like 2

Only here once

Share this post


Link to post
Share on other sites

Static Compression ratio

I used perspex and a syringe. Heres my calcs. I couldn’t find the manufacturers gasket spec, so I used figures I have seen else where. When I went through it with the expert we calculated 7.7 CR. Heres what I got after measuring.34ED97EC-36DD-4130-B859-E9BBE2D5247B.thumb.png.922c6ea5b3c911cbfa772ed05d6723e9.png

 

  • Like 1

Share this post


Link to post
Share on other sites

So if this is correct the CR has increased to half way between the HC and standard Turbo. The question now ( I’m not qualified to answer) what would be the effect of this and is it necessary to adjust the boost pressure? 
remember standard Turbo    7.5.1    
                    HC.                           8.1

Fabians Bond car.                7.76.

assuming the gasket thickness is correct? 

Share this post


Link to post
Share on other sites

At 7.76:1 you would probably be fine..   You could also just tweak  boost back a fraction to get spot on ..  You can use one of the on line calculators to give boost for required final C/R.     

I have to take my hat off to how quick you did all the measurements..   well done .  

  • Thanks 1

Share this post


Link to post
Share on other sites
10 minutes ago, CHANGES said:

At 7.76:1 you would probably be fine..   You could also just tweak  boost back a fraction to get spot on ..  You can use one of the on line calculators to give boost for required final C/R.     

I have to take my hat off to how quick you did all the measurements..   well done .  

Thanks Dave, I’m glad you brought this up its nice to know exactly what the CR is and I would not have measured it without your input. I will look into the boost correction and modify it as required.

Share this post


Link to post
Share on other sites

6EA3C71B-7C03-4C82-BBA2-5FE2FC2D3BC2.thumb.png.e84dea32bc11dce4cc7b59d9e858367e.pngI am thinking using this graph to stay within the original engine parameters I should reduce the boost from 8 to 6 psi?

Share this post


Link to post
Share on other sites
3 hours ago, Lotusfab said:

Static Compression ratio

I used perspex and a syringe. 

Out of interest did you balance the combustion chamber volumes? 😀


Cheers,

John W

http://jonwatkins.co.uk

Share this post


Link to post
Share on other sites

Combustion chamber volumes, of course! 😄😄😄Heres my piston check, little grease on the edges to hold the water. Same  for the head with the spark plug in.1D9BCF64-DF71-4FC5-AFA4-191588FE79B6.thumb.png.2f943894d1ee4905427aceca43e3ccf0.pngI think the wastegate will have to start to operate at 5.5 PSI to achieve 6psi max. I don’t have any practicle experience of this, its entirely theoretical.  I know the other engines are running standard wastegates. I think the spring length will have to be shortened to achieve reduced psi  or a shim made for the casing. The HC has uprated cooling and I’m not racing, I want reliability, so it might be wise to reduce the boost to give the same final compression as the stock Turbo.

Now I really must get on with the build!😄😄😄😄

Share this post


Link to post
Share on other sites

This time I have dotted the I’s and crossed the T’s twice!ACDF1AED-E160-4B31-B5CB-986F955F7619.thumb.jpeg.39434333c49706a309875327b63377f2.jpeg

EE769E67-67FF-4950-B925-8CFF95B8718F.thumb.jpeg.68d94acdd798ee7e6c49e7100e36c055.jpeg80FBCA05-32FE-426E-8E07-548A8ECC9231.thumb.jpeg.663fde1dc6b4105836be3154bfeaa403.jpeg

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...