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kehoeautomotive

Boost regulation

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So I took my buddy's car out for a spin today since he told me that the engine was "cutting out" under acceleration. I quickly determined that the boost was going to high and I'm guessing that the computer is shutting off the fuel. There is a valve under the turbo that I suspect controls the boost. The manual I have shows a completely different set up that this car has. Here is a picture of the valve. Is there supposed to be a bolt in the bottom of it? I also noticed that his turbo return line is leaking oil so I brazed in a new return line while I was poking around under the car. Does anyone know where I can get a manual on this turbo set up? Did a bolt just fall out of this? Or does it have some sort of vacuum seal or spring inside of it?

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Missing adjustment bolt?

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That's what I was wondering. The manual I have shows a vacuum dash pot with an arm that goes to an internal valve. This set up does not have that. I have no idea without a manual on this set up if it's supposed to have a bolt in there.

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There's no adjustment bolt on the Lotus wastegate.

Edited by sailorbob

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This port is open to ambient pressure as per design, your problem lies somewhere else.

There is a spring and a diaphragm in there, boost is not adjustable, the spring tension takes care of limiting the max boost if I remember well. I'm sure some turbo whiz will chip in.

I don't have my manual close but if I remember there is a diagram in there.

 

Edited by Mesprit87
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Thanks guys for chiming in! I will take that gizmo off, clean it up and put a new diaphragm into it and see what happens. I will also make sure to beat it with my favorite rock as well.  

 

I also made made up a new turbo return line too. Here is a picture of it. Can make more if anyone else needs one as I now own the correct Teflon tubing that the correct crimp shells and dye. Here is the picture.

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Nice piece of pipework!! As for the wastegate, there's already a load of stuff about it on the forum, currently.  I have mine in bits and am making up some internals to render the boost adjustable, using the hole in the bottom of the wastegate for a bolt and locknut to set the pressure. The standard wastegate has no means of adjusting the boost...this is preset by the spring fitted and the thickness of the aluminium spacer below the gasket. The gasket gets holed...in my experience, they last about 10 years apiece. S&J sell them for about £65 each...sounds a lot, but the first one I bought was in 1988 and cost me £130!! You need two special gaskets, too, one either side of the diaphragm. You may find that the four bolts holding the wastegate together are seized in their threads...the first time I dismantled mine, three of them sheared! I had to turn the base through 45° and redrill and tap as needed..used stainless fasteners and it has goven no such problem since.

Running these engines at more than standard boost is a quick road to disaster. I'm making mine adjustable as all I get is 6psi instead of 8....so I want to squeeze it up a bit.....since it's in bits anyway.....

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You remember the other source you had for turbo stuff in the US john?

This guy is from the states so it would be cheaper for him.

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I would be very interested in one of those oil return lines! Did you make the whole thing or re-use the end fittings from the original?

The computer cant be shutting off the fuel as there isnt one. But it could be going lean and as already mentioned overboosting is a serious problem with possibility of melting pistons.

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On March 11, 2016 at 17:03, Andyww said:

I would be very interested in one of those oil return lines! Did you make the whole thing or re-use the end fittings from the original?

The computer cant be shutting off the fuel as there isnt one. But it could be going lean and as already mentioned overboosting is a serious problem with possibility of melting pistons.

I used the original fittings for the oil return line. I can whip up the line in about an hour and it fit perfectly. Mail me an old one and I will fix it up. Just do it soon as I'm moving to Australia this summer.

The car does has a fuel cut computer/module as well as a computer that controls the frequency valve and fuel enhancement items for the k jet system. 

We took the regulator out and fixed it. The valve inside of the boost regulator was rusted in place. I beat on it with my favorite rock, put anti seize on the shaft and installed a new diaphragm.

It's nice to see the car back on the road and running like new. Even got the idle up for the Ac system adjusted just right.

Now we have to fix the fuel gauge. I plan on taking the sending unit out of the tank and testing it. I suspect it is stuck too. I will to clean it and then beat on it with my favorite rock.

A Chinese luck dragon once sat on my favorite rock and that's why it can fix so many things.

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4 hours ago, kehoeautomotive said:

The car does has a fuel cut computer/module as well as a computer that controls the frequency valve and fuel enhancement items for the k jet system. 

 

Thats interesting. I always thought the early cars which had that type of wastegate never had the K-Jet system even on US cars. They must have gone over to the K-Jet very early in the production run on the US version.

The oil return line I was going to keep "in stock" as mine isnt currently leaking although they often do. But I will see if I can get another one to send. Thanks!

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20 hours ago, Andyww said:

Thats interesting. I always thought the early cars which had that type of wastegate never had the K-Jet system even on US cars. They must have gone over to the K-Jet very early in the production run on the US version.

The oil return line I was going to keep "in stock" as mine isnt currently leaking although they often do. But I will see if I can get another one to send. Thanks!

Glad it had it. I may have saved the engine since we've never experienced over boost we could have destroyed it. Does your car have a fuel injection? Is it purely mechanical? 

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K-jetronic started in 1986 for the G-bodied North american models, exact same as what you have in the Stevens '88 and some '89 IIRC.

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On 3/10/2016 at 11:22, molemot said:

Running these engines at more than standard boost is a quick road to disaster. I'm making mine adjustable as all I get is 6psi instead of 8....so I want to squeeze it up a bit.....since it's in bits anyway.....

There is a bright ali spacer ring separating both halfs of the wastegate. These rings were added as a quick fix to re-calibrate the boost level at which the w/g opens.

Proper length of the spring should be 105-110mm.
Normally, w/g starts opening at 7-7.5 psig with the ring, and at 9-9.5 psig without it. Service notes specify 9.5 psi as a spec.
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 in the early turbo cars, which had to do with the (early, cast) pistons crowning and causing excessive clearances which caused hot blow-by contributing to the ring land failure resulting in broken rings/ pistons. HCI and later cars received forged Mahle pistons, which solved this problem.

Make a couple of gaskets to insulate the diaphragm from the hot housing flange and the stem.
I used "Graphoil" gasket material from the eBay.
You will need to make two ring-gaskets, one on the "hot" side (0.030" thick), and a second one (0.010") at the bottom.

For more information Google: " X180 External waste-gate renovation."

Edited by MrDangerUS
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Crikey....another John D....(!)

Very useful info. I knew that the thickness of the aluminium spacer was used to set the boost level, but actual figures have been elusive. Didn't realise that the X180 shared the same type of wastegate as my 82 turbo...and that now has forged pistons, so ought to be better than the cast ones.  Thanks for that!

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37 minutes ago, molemot said:

Crikey....another John D....(!)

Very useful info. I knew that the thickness of the aluminium spacer was used to set the boost level, but actual figures have been elusive. Didn't realise that the X180 shared the same type of wastegate as my 82 turbo...and that now has forged pistons, so ought to be better than the cast ones.  Thanks for that!

I didnt realise that either. When did they change over to the integral wastgate?

 

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5 hours ago, Andyww said:

I didn't realize that either. When did they change over to the integral wastegate?

89 MY in US. In UK might be 88 MY.

 

 

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18 hours ago, molemot said:

Crikey....another John D....(!)

 Didn't realise that the X180 shared the same type of wastegate as my 82 turbo...and that now has forged pistons, so ought to be better than the cast ones.  Thanks for that!

X180 was a code name for the re-engineering programme which produced the new Stevens body (starting in 1988). '88 Federal was the last year of Bosch CIS K-Jetro injection. '88 in UK had carbs.

In 89 different turbo was introduced (with internal waste gate), and it was called Esprit Turbo SE- X180 style. So, X180 is a Body Style.

X180-R is a designation for the 20 street legal SCCA/IMSA racer car replicas built in 1990, and a further refined versions of the 91 car. They had full roll cages and many other racing upgrades, like brakes, air foils, tyres, wheels,etc.

Edited by MrDangerUS

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On 3/28/2016 at 10:46, Mesprit87 said:

K-jetronic started in 1986 for the G-bodied North american models, exact same as what you have in the Stevens '88 and some '89 IIRC.

My stevens has electronic fuel injection from a GM. Looks to be the same system as a chevy Corisica or perhaps a Cavalier.

 

This has been very useful information. Thanks so much. There service manual has a different set up in it so I had to go in blind. But the car is running great. The fuel sending unit was stuck and I beat on the top of the tank with my favorite rock and it now works again. I'm checking the fuel filter for rust not it has a hundred miles on it. If I find any, I will pull the tanks.

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