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912 Engine on Dyno - Engine/Ancilliaries - The Lotus Forums Jump to content
markjonesx

912 Engine on Dyno

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Engine looks nice, what did you paint the cam covers with? :thumbsup:

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What spec are the engine innards?

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It's all completely standard apart from new pistons as my old ones were out of tolerance.

Nothing special or trick, just set and built correctly.

Crank/rods/piston/flywheel were all balanced professionally, runs as smooth as silk.

As soon as I have the dyno' print outs I'll post these also.

Will probably show another 5-8BHP with the 4-1 manifold.

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Very pretty! When I did my cam covers, I wiped the paint off the machined ribbing and lettering; seems to make them stand out more?

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Nice job Mark. Looking at the max hp rpm, is that with two 107 cams?

A well known head guy on our west coast said on the dyno he picked up 30hp using a lotus elite airbox, the one with the single 3 1/2" inlet.

I'm building a 907/912hc hybrid, and with big overbore, should end up at about 2290cc's, and looking to build 225hp on std valves. Here is my topend and paint job on the cam covers, self ported the 912hc head.

topend_001.jpg

Brian

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I'm building a 907/912hc hybrid, and with big overbore, should end up at about 2290cc's, and looking to build 225hp on std valves.

Looks nice, did you gas flow the head yourself?

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I did not 'flow' it John, but did send it to Richard Reymen at West Coast Cylinder Heads, he has it currently. He is installing new bronze guides and seals, new stainless valves, cutting the seats, full comp valve job, skimming, and shimming the cams. He has ported dozens of lotus heads. He was quite pleased in what he saw, and said absolutely nothing else needed to be done, that I had worked all the areas that needed attention, and was quite impressed with what I had done with the bowl porting. He is the most respected lotus porting specialist this side of the pond. They don't do very many lotus heads these days as compaired to years ago, now it is all chevy cnc 5 axis porting of LS7 heads and such.

I shared with him I was quite happy with his analysis, considering that was my first 'head job' at age 62. A little head never hurts! :)

Richard is the one that had the 30hp experience on the dyno with the elite air box (no filter) verses just the velocity stacks. All he could attribute it to was 'acoustics', just like a tuned header. He was working on a ported and cammed 2.2, was trying some jetting changes, and was around 205-210 hp, and the jetting was not making much difference. Said he went back to the beginning jetting, put the elite box on, and pulled 240hp! I'm going to see if I can plumb in the elite box, not sure enough room up front under the engine cover.

I would be glad to list some of my design and build ideas I am trying if you like, but I feel pretty bad that I have intruded on your thread Mark.

Brian

Edited by bharper

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Mark,

Is that indeed 107 cams? I take it you went high compression pistons? Looking at the dyno run, I would want the 4-2-1 header that run was made with. Once you get a full breakin on that engine, the numbers should increase even a little more.

I have no idea why you would want to go a 4-1, you will lose a lot of the bottom end torque. The only reason you might pick up some additional top end is if the primary tubes are too short, which a well known British available 4-1 has. Most 4-1's do not measure that much better than the stock lotus setup. If you are running 107's, that would not be a good match up.

I am in the queue for a custom 4-2-1 header on this side of the pond from lotus esprit parts dot com. I drool over the lotusbits stainless setup, but just can not afford it once you factor in shipping.

Your esprit build looks absolutely fantastic!!! Can see the love, time, and skill that has been put into it.

Brian

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I think the cam are std 104, I'll have to check.

 

The pistons were a slightly higher compression, these are the same pistons SJ use from Omega.

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Cam covers look great!!  Going to redo mine now with the Lotus script and rib painted.

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If those are the original cams, I would expect both are 107's.  If you look right behind the cam pulleys, a 104 will have 4's, where a 107 will have 7's around the circumference of the cam.  The hp peek sure appears to be that of 107 cams....

 

Brian

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