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Calibrating the Turbo Wastegate.... - Page 2 - Induction/Turbo/Manifold/Exhaust - The Lotus Forums #ForTheOwners Jump to content


Calibrating the Turbo Wastegate....


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:thumbup: All's well that ends well :)

88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

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Now if you had trailered it to my house instead, a few miles away we could have fixed it in a few mins, I even have spare hoses! :)

But glad it all got sorted. "Unable to proceed" is never a pleasant experience!

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Andy...had I only realised.....!! Still, it's all about the experiences one gets....and this was one to add to the list!! Fourth time on a flatbed; first was when the cambelt broke a few days after I bought her in 1988...complete with full service history from Bell & Colville, cambelt change service signed off...( proper scrutiny of the book suggested this was a forgery!!) Then a round trip to our workshops in Acton in 1996 so I could spray her (neighbour in Kew had been complaining of blue washing) and this was the fourth. Very pleased with everyone concerned.... S&Js new premises are streets ahead of the old gaff, and work on shop and so forth proceeds. Spares are no longer quite so crowded...over a million pounds worth, Steve reckons. Everyone agreed with the "red hose v crossgate adjustment" thing, too......(!)

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Good to hear you didn't get half as wet as you usually do in your garage... I still remember one of your "wettest" story! Glycol doesn't rime with Lotus but they sure go hand in hand!

Something I learned about cars or planes, it all works until it doesn't anymore...sometime there is no way around it!

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  • 3 months later...
  • 5 months later...

External waste-gate was made by NormaiAir-Garrett Manufacturing, Melbourne, Australia. Originally, it was made for aviation industry (hard to believe, it weighs a ton!).
Faulty w/g may lead to poor performance or even the engine destruction. See 88 Turbo Esprit Runability Issue

Boost is calibrated by adding/removing the aluminum ring (spacer) sandwiched between upper and lower half.

These rings were added to re-calibrate the boost level at which the w/g opens. Proper length of the spring should be 105-110mm.
Normally, it opens at 7-7.5 psig with the ring, and at 9-9.5 psig without it.
Majority of 84-87 (and some 88') Turbos had their boost restricted to 7.5psig by the means of installing an aluminum spacer ring between two halves of the waste gate.
There was an issue on the early turbo cars, which had to do with the cast pistons crowning and causing excessive clearances causing hot blow-by contributing to the ring land failure resulting in broken rings/ pistons.

HCI and later cars received forged Mahle pistons, which solved the problem. Spacer ring thickness was reduced on these cars and some Federal cars had them removed.

I have removed the ring and added two 0.8mm thick graphite gaskets ("Graph(f)oil" from eBay) to protect the diaphragm from melting. Additional 1mm graphite disc was added above the piston to protect diaphragm from hot gases blow-by trough the housing bore to piston stem clearance gap. This clearance should not be larger than 0.0010".

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Edited by MrDangerUS

MrDangerUS

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Once you separate two halfs successfully, examine carefully the valve stem to housing clearance. If excessive, take it (and valve) to a reputable machine shop to press in a 3/8" ID steel guide with an internal spiral grooves. It will significantly reduce hot gases blow by. OE housing has a BARE HOLE (no sleeve) and often wears off extensively.

Guide spec: Valve guide, hard steel, spiral bore, ERS 02282

New stem to guide clearance should be 0.007" -0.010".

Don't use bronze guide sleeve. It may not survive due to a long term harsh environment (high temps and no cooling jacket !).

Stem is hard chromed and it should not have any significant wear, but check the valve stem diameter in couple spots.
DO NOT attempt to grind or polish the valve stem!

MrDangerUS

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3 hours ago, MrDangerUS said:

 OE housing has a BARE HOLE (no sleeve) and often wears off extensively.

 

Bear in mind that cast iron can run well with virtually no lubrication, so I suspect its a bare hole by design (in common with cylinder heads that have cast iron valve guides or no guides at all....

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On 07/07/2016 at 03:27, Mesprit87 said:

Good to hear you didn't get half as wet as you usually do in your garage... I still remember one of your "wettest" story! Glycol doesn't rime with Lotus but they sure go hand in hand!

Don't talk to me about "wet"....I was in the UK all winter getting chemo for the prostate cancer. When I got back to the French hovel I found that, although I had turned off the water, the stopcock had needed about 10 degrees more turn.....so when the freeze came in January, the pipe to the water heater burst; come the thaw, and the trickle through the stopcock and burst pipe was enough to flood the place, over the 8 weeks or so before I got back. Kitchen floor, hall, toilet, bathroom....all very sloshy. Of course, it drained through the floor onto the workshop ceiling and descended in several slow motion Niagaras upon the workshop contents....viz. the Lotus...and the floor of the workshop was about 2/3 under water. I wasn't very happy...this was when I discovered that the stopcock needed a rather more Herculean effort than I had used before my departure.

We got the place dryish with mop and bucket and squeegee. Then, after a few days, it was time to fire up the washing machine and get the first tranche of washing done. So I carried it all to the workshop in a Useful Bag...and opened the door to the washing machine..

It was like that bit in The Dambusters just after the Mohne Dam had given way. The machine had been full of water...so full that there was no obvious level line across the glass door...and all this came spewing forth over Moley's finest carpet slippers...it seemed to keep on coming...I almost expected some canoe types to be riding the wave, or surfers "in the tube".....and the workshop floor was once again awash. Happy days.

Now the insurance assessor has been and I have €5000+ in my account and the estimates are coming in I do feel a bit better...just waiting for some decent weather to get the Lotus clean and shiny again. Pleased to report that, even after all this, she fired up first prod as usual.....

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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Oh! mon ami...

What a return back home!

We're a little off topic but the important bit is you getting rid of that cancer.

Good luck with everything.

Something I learned about cars or planes, it all works until it doesn't anymore...sometime there is no way around it!

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