Omega Owners Forum
Chat Area => General Car Chat => Topic started by: Shackeng on 11 May 2013, 16:25:31
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Some of you may be interested. Chatting to a friend this morning who has an engineering company that made camshafts for Lotus who put them in the LC engine.
Not a lot of people know that, but now you do. ::)
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Lotus Carlton cams are standard 3.0lt 24valve jobbies. So I fear your friend is mis-informed
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Lotus Carlton cams are standard 3.0lt 24valve jobbies. So I fear your friend is mis-informed
I'll check with him tomorrow, he mentioned 2 stage cams???
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maybe an after market kit but LC's don't use any different valve train bits than the gsi except for exhaust valves which were same in size but apparently filled with sodium.
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maybe an after market kit but LC's don't use any different valve train bits than the gsi except for exhaust valves which were same in size but apparently filled with sodium.
He definitely supplied Lotus with the camshafts, and thought they went into LC's. He owns a specialist engineering co. and supplies many companies with parts, so he may have got the application wrong, I'll ask him today again. :y
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Update. It was about 1990, Lotus were importing Opel cars (Lotus Omegas?) and were supplying engines for other uses. He supplied camshafts that had different profiles which were moved longitudinally hydraulically at higher engine speeds to give a different profile. He does not think that they tried them in the Carlton engine, (despite his musings yesterday) and thinks they were for experimental use anyway, as they only produced a small batch.
Has any heard of any engine in production that used such a design?
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Think I'll go with Doz's explanation :y :y
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the standard gsi 24v also has sodium filled valves :y
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so lotus carlton was 3,6 twin turbo and used same cams as 3.0 normal aspiration then ?
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Yep that's the gist of it. In fact the only change to head was some machining to lower the compression ratio. Otherwise that's the same to.
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so did lotus bore out 3.0? I know chevy stovebolt is about 4 litres so surprised they didnt use that block as basis or v8 for that matter-either way LC was awesome then and now :y
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No boring, stroked to 3.6.
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Which begs the question as to what Irmscher did to make the 4.0 24v lump :-\
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stroked it even more!!!! Had to notch the block to allow for the throw on the crank
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Update. It was about 1990, Lotus were importing Opel cars (Lotus Omegas?) and were supplying engines for other uses. He supplied camshafts that had different profiles which were moved longitudinally hydraulically at higher engine speeds to give a different profile. He does not think that they tried them in the Carlton engine, (despite his musings yesterday) and thinks they were for experimental use anyway, as they only produced a small batch.
Has any heard of any engine in production that used such a design?
you've just described the Rover VVC system quite well. Its just one form of variable valve timing
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The Irmscher 4.0 was bore + stroke
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You may be wrong there. There isn't a lot of meat to be boring them which is why they are always stroked
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98mm vs. 95mm 8)
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Oh god now I'm gonna have to go down to the back of the workshop and measure my old block I'm positive both 3.0lt and 4.0 lt 24 valves were 98. 3.6 Irmscher 12 valve was 96. Do you know how dangerous my workshop is? There's all sorts of strange and wonderful life forms down there
Where you getting your info from?
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Well I stand corrected. As they say everyday is a school day. 98 versus 95. I've got a spare 3.0litre engine I rebuilt almost 20 years ago. Back then pistons were mega expensive. The engine had covered 208 k miles. The machinist managed to find some pistons which were half the price however they were bigger dia. I ended up with a lump just under 3.1 and I had a ported head done for it. Covered around 4 k miles before I had to scrap the car. I kept the engine and it's sat in the workshop all covered up with the pots and engine filled to the brim with oil. Must get it fitted to the gsi. It went like the hairy clappers.
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Oh god now I'm gonna have to go down to the back of the workshop and measure my old block I'm positive both 3.0lt and 4.0 lt 24 valves were 98. 3.6 Irmscher 12 valve was 96. Do you know how dangerous my workshop is? There's all sorts of strange and wonderful life forms down there
Where you getting your info from?
I have some old Opel information.
it seems they did play "musical bore sizes", especially if you include 12v and the likes of Mantzel, etc.
But as the question referred only to the Irmscher 4.0, I'm confident that the answer is 98mm ( in addition to the long-throw crank )