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Esprit Turbo project car - part3 - the further continuation


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Thanks. Yep that will be the plan. I’m running 43s and still have a lean spot. If I pull the choke the stumble is gone and it really flies. 

 

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1 hour ago, 910Esprit said:

Are you going to install one of his 'reversed' crownwheel/pinion sets?

As a point of note when I change from 40's to 43's I need to turn in the mixture screws exactly one full turn to achieve the same idle CO2 - my datum is 2 full turns for 43's 3 full turns for 40's.   (measured with a gas analyser).

NB - I passed my MOT yesterday and he was very impressed with the emissions readings until we spotted the probe had fallen out half way through the test!

 

 

Have you got a lambda sensor on the exhaust?

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The whole point of 3-piece wheels is so the correct offset can be achieved for the car in question without the need to cast or spin them specifically, which is prohibitively expensive for low volumes. Single piece wheels can only have so much material machined from them before they become too weak.

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Margate Exotics.

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On 01/04/2021 at 12:57, 910Esprit said:

Are you going to install one of his 'reversed' crownwheel/pinion sets?

As a point of note when I change from 40's to 43's I need to turn in the mixture screws exactly one full turn to achieve the same idle CO2 - my datum is 2 full turns for 43's 3 full turns for 40's.   (measured with a gas analyser).

NB - I passed my MOT yesterday and he was very impressed with the emissions readings until we spotted the probe had fallen out half way through the test!

 

 

My car needs only 1 more MoT and then its exempt! 

All my new jetting has arrived, can’t wait to fit and test over the next week.

Will be interesting to see what effect the smaller choke and other jet changes makes. The one thing that can’t be changed very easily is the progression hole drillings. If you make them larger there is no going back! 

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I will film the rolling road stuff (if I am allowed). It will be very interesting. My brief is I don’t care about power. I want a car that drives smoothly without hesitation during the acceleration. 

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I will post all of the jetting info in detail. I have heard some of the professionals say they have never been able to get rid of stumbles on some cars. I am pretty determined to make this car drive perfectly. Reading about the Dellortos the stumble is a common problem. People who keep going with the jetting seem to achieve good results.

I have been thinking of changing the pump jet to a smaller size and increasing the delivery volume. I think this would sustain the extra full burst   for longer as the HC pump jet is a 35 and not a 48 H. This is something I think I will leave until the results of the idle jet/idle jet holder and smaller choke are known and understood. 
I think I will stick with these carbs initially, but if I cannot perfect the car with them I will look at other options.

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1 hour ago, Lotusfab said:

NB - I passed my MOT yesterday and he was very impressed with the emissions readings until we spotted the probe had fallen out half way through the test!

At my MOT last December Gerald said that tester commented that the emissions were better than a lot of modern cars.

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This :

https://vintagetechnologygarage.groups.io/g/sidedraft

The host, Keith Frank, is a man of high technical capacity who's been exhaustively analysing carbs of the sort for many years. He has emulsion tubes for the Dellorto's which, as with those he's done for the DCOE's, quite transform the roll-on behaviour. His products have been widely lauded, and his analysis of what actually occurs within the subsystems ( circuits ) is quite illuminating.

Cheers

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As long as we talk about a set of original OZ Futura Modular, which was made specifically for the Esprit and also other cars, say big Mercedes and others, the wheel's individual parts are made from an center 5 spoke star, an inner drum and an outer lip. All bolted together with a various number of bolts, depending on wheel diameter.

Those bolts are locked with nuts on the inner drum's rearside, and loctited. A bead of sealant is then laid in the center cavity that is between the three main pars, once bolted up in the factory. Same is done if you do them yourself. The procedure of tightening is described on my own thread. Completely done, balanced, and works perfectly.

The star are the most important part. The outer lips and inner drums can be bought either from OZ second hand wheels, or as copies from other brands, such as Felgenfuchs, and their aluminium outer lips or same in radinox stainless steel.

Despite me moving up in width, the completed wheel with it's 315 tyre, is still lighter than for example another Lotus original wheel, such as AWI Monobloc.

I used well proven bouble and acid free sealant.

Running these wheels gives the Esprit (1989 onwards; not 1988 because it's got smaller wheel arches), an enormous mechanical grip. It's very noticable, and is glues to the road.

Kind regards,

Jacques

 

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Nobody does it better - than Lotus ;)

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Well the new jets and idle jet holders are installed. I now need to remove the plenum to get access to the chokes. In theory making the choke smaller should richen the mixture due to the increase in venturi effect. I have no practical experience of this, just what I have read and been advised. I will have to retune the car and see what happens. I stumbled across a rule of thumb for calculating the main jet sizes. Interestingly the Lotus selected sizes don’t match the rule of thumb calculations!

My wheel is fully cured and tyre should be back on by Tuesday. Looking forward to seeing if these jetting changes sort the problem. It will still be off to the rolling road to perfect the set up, then its job done I hope!

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I was just thinking if it would Ben possible to reinforce the wheels with something like a giant G clamp and rubber/wood, so that when the higher pressure bangs the tyre into place, the rim is supported and doesn’t have to take the whole hit by itself. 

Just a thought ...

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I think it will be fine if sufficient lubrication is on the barrel and wheel. Tyre bead sealer needs to be on the lip as well. I am using Voodoo motorsport to put my tyres on from now on. My local garage isn’t up to the task. They treat it as a modern wheel, which you really can’t. They have cost me four days of hard work and fractured a wheel lip so far! 

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On 01/04/2021 at 17:28, Chillidoggy said:

The whole point of 3-piece wheels is so the correct offset can be achieved for the car in question without the need to cast or spin them specifically, which is prohibitively expensive for low volumes. Single piece wheels can only have so much material machined from them before they become too weak.

Makes sense. I had assumed (probably wrongly) that they came from a racing background where the wheel/tyre could be assembled without carrying around a tyre fitting machine.

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7 minutes ago, Andyww said:

Makes sense. I had assumed (probably wrongly) that they came from a racing background where the wheel/tyre could be assembled without carrying around a tyre fitting machine.

Yes, I think you’re right, originally developed for race cars. Having rebuilt several different sets over the years including a dreadful set of Compomotives, it’s a slow process and of course you can’t afford not to get it right first time, which makes me wonder whether race teams ended up just carrying different wheel sizes/offsets for testing purposes.

If I had the choice, I’d have a single-piece wheel every time!

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Margate Exotics.

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1 hour ago, Chillidoggy said:

 

Nope, you've lost me there. Care to elaborate?

Its all about what they look like! 

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