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1987 Turbo Esprit HCI
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66 Posts
Discussion Starter #1
I had the chronic issue of my manifold coming loose.
With the engine out, and me ready to put a tube header on, which fasteners should I use to avoid the loosening problem forever?

I have the 12point 12mm squish nuts, the Aerotight 13mm nuts, and with my Alunox manifold came another set of 13mm metal lock nuts in a different style. (They're all metal lock nuts, it just didn't photograph well)
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Since I was missing 2 of the locking tab plates I ordered a set of stainless m8 Nordlock washers instead. If that's a mistake I can always order some replacement tab plates, but they didn't seem to work before.
Anyone who has removed the manifold with the engine in the vehicle is a far better mechanic than I am. It was hard enough on an engine stand. I can't imagine trying to wiggle my arms past everything while it's in the vehicle.

As far as the manifold and turbo gaskets go, I have the same question pretty much.
I have the HCI ones, the regular Esprit ones, and the ones Alunox supplied. Which are my best option?
The manifold to turbo gasket Alunox supplies is the puffy perferated looking kind vs the laminated steel kind that the Lotus came with.
The alunox gasket looks like it could flow better, but I'm wondering if the gasket material between the top stud and the opening is enough, the other two designs have a lot more meat there.
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As always, thank you for any input. For how small this community is you guys sure know a lot and respond quickly.
 

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Those composite gaskets should never be used on turbo manifolds! What is that company thinking? They get blown out in no time and leak, then lose compression and the fasteners loosen. Ding bats!
 
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It might be worth looking at "Stage 8" locking fasteners. I am using them on a V8 with very good results. Last time I worked on my son's '90 Esprit I tried fitting some but the tolerances between the manifold and the stud were too close for the configuration of tabs I had on hand. I believe a little imagination and engineering cold provide a possible locking tab for the 4 cylinder. The 4 cylinder will probably be coming out sometime in the near future and I plan to try to work something out.
 

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1987 Turbo Esprit HCI
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66 Posts
Discussion Starter #7
Are you not using lock plates?
Two of mine were lost on the road somewhere, They didn't seem to work last time, and that seems to be a problem many people have had. I don't don't think they'd work with the 12point nuts if I use those either.

Those composite gaskets should never be used on turbo manifolds! What is that company thinking? They get blown out in no time and leak, then lose compression and the fasteners loosen. Ding bats!
From what I understand Lotus originally did it, but they moved to the laminated steel ones for the high compression engines.
I was leaning towards using the HC Lotus ones, and I think you've made up my mind.
 

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It's been a few years, but if I recall, the most trouble I had was losing the stud on the end at #4 top. I put new stainless studs in with loctite, new distorted thread stainless lock nuts and lock plates that I had water jet cut from my own drawing. I didn't have trouble after that, besides the cast manifold cracking again and going to my own 304 stainless design/fabrication. The manifold was probably the only thing salvageable, and at the $226 insurance auction for what was left, a bargain.
 

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Dreaded Prior Owner
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My 910 seems to hold together with copper-coated distorted thread 6 point 13mm nuts over Nordlock washers on stainless studs, using the #2 style gaskets under my Alunox manifold. I don't have a whole lot of miles on the combo though. On my head the exhaust ports/manifold flange ID did not quite match, so I trimmed a bit of the interior of the gasket to match the bigger dimension.

My thought is that the Alunox manifold is much less likely to have sealing or stud issues, as the individual runners can float in the collectors, and the joint is not trying to compensate for the expansion of one big piece of dissimilar iron.
 

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1987 Turbo Esprit HCI
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66 Posts
Discussion Starter #10
My 910 seems to hold together with copper-coated distorted thread 6 point 13mm nuts over Nordlock washers on stainless studs, using the #2 style gaskets under my Alunox manifold. I don't have a whole lot of miles on the combo though. On my head the exhaust ports/manifold flange ID did not quite match, so I trimmed a bit of the interior of the gasket to match the bigger dimension.

My thought is that the Alunox manifold is much less likely to have sealing or stud issues, as the individual runners can float in the collectors, and the joint is not trying to compensate for the expansion of one big piece of dissimilar iron.
Since you have the manifold on an 85, what was your solution for the pressure signal for the waste gate?
 

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Dreaded Prior Owner
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My situation probably doesn't apply to your setup.
I bought the Steven's model manifold in order to use an internal wastegate turbo. I pull wastegate control pressure right off the compressor scroll through a solenoid for boost control. Electronic boost control is based on actual manifold pressure sensed by my MAP sensor off the plenum, with PWM control by my Megasquirt ECU.
 
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