Lotus Excel

Has anyone out there ever fully "Blueprinted" a 912 engine and if so what were the results? Following a cylinder head failure on my SE I am considering a full engine rebuild!

Give the boys a call at LotusBits, Mike Taylor is running big horsepower from the 912, and i run one of Mikes earlier race engines. I run about the 200hp at 8000 at the moment, this is with porting and big cams + Four branch with larger bore exhaust...........Will be looking at adding mapped ignition and throttle bodies at some stage, but not necessarily at the same time.

Thanks for that "Previously Jerry". I am wondering about the realms of flywheel,crank,con-rod and piston ballancing as well as head work etc. Any ideas folks?

There was an engine on E bay that had been rebuilt, blueprinted with a ported head and tubular 4 2 1 manifold it was 220hp

General story is you need a tubular manifold to get a decent output + a headport and figures are between 200 - 220, i'm guessing a 200 to 210 on a stock engine and 210 to 220 on a bluprinted one

I had a blueprinted / balanced Rover V8 in a TVR I used to run. It doesnt really add to the power fugures of the engine, but it makes the engine feel that it will put up with you thrashing it because of the smoothness, so in a way, it will make it faster. My party trick was to stand a twenty pence piece on its edge on top of the running engine! Im not sure about the 912 but I also had a light flywheel on the Rover, which makes it also rev cleaner and quicker. If you go down this route, I would also get the engine balanced properly.
Blueprinting on its own just optimises all the engine bits. If you get it tuned properly this should be done anyway.

Bash

Thanks for that Bash. It's clear that whilst the bottom end of the engine could be inproved by ballancing obviously if the head is allowed to "breath" properly it will result in an improvement. Another 40 or so bhp sounds interesting! Looking at the "LotusBits" site certainly makes things plain. Does any member know of an engineer in West Yorkshire who can do the head work?

Hi, why not speak to Mike at lotusbits about having him do the headwork, he gets it done for the race engines and knows the engine, could be better than going to someone who has no experience of the 900 series head.

I agree, if you want a proper job, go to somebody who knows what they are doing because they will have flow benched numerous heads to get a result, no doubt ruining a few along the way. New valves, three angle valve seats with ports blended into the seats, matching the manifold and exhaust ports and a different exhaust cam will all realise small improvements, but, if you pay for sombody to do all these things, who may know there way around engines in general, you could end up paying as much as you would going to somebody like Mike who really does know what works, and has proved it in his rally car.

hope this helps

Bash

Out of curiosity how much (ball pak figure) do you think it would cost to have the engine fully rebuilt, blueprinted and blanced?

According to Mike Taylors website, anything from £4000 to £10000 depending on what spec you want


http://lotusbits.com/upgrades_engine.html

That does seem quite reasonable for a tuned/rebuilt engine

Just out of curiosity if anyone has had an engine rebuilt/blueprinted, did it improve the smoothness much?

My engine is fine once it's warmed up till about 6400 RPM, before that point vibration seems about the same, and it's generally quite smooth, but after that the vibration get's much stronger and more noticable were as before that point you don't really notice the higher rev's except for the engine note, after that i can feel it through the gearstick wheel

Would a rebuilt balanced engine be totaly smooth throughout the range, or is this very top end increased vibration simply inherant in the design?

I have no vibration all the way to 7700

Doesn't the rev counter only go up to 7000???

Jerry has a tuned 2 litre, if i recall from prev posts

When i say vibration it's not like the whole car starts shaking, but below those RPM levels, you can feel the engine thrumming away through the gear level, but on a very low level, and i'd say normal level, when driving around you just don't notice it unless you put your hand there and feel for it if you know what i mean

But on going past 6000, that light thrumming starts to get a lot more noticable and i can feel it when i change gear, below those RPM levels i dont really notice it when changing gear, and was wondering if others had the same thing and if those with a blueprinted/freshly rebuilt unit had it ?

Mine is without PAS and AirCon belts and there is no water pump belt either. The only belt (apart from cams) is the to the alternator.

Before getting rid of these accessories I had rev related vibrations but that turned out to be the usual broken PAS pump mount / PAS pump out of alinement.

With only an alternator to drive mine is very rev happy and smooth.

But I do appreciate that a "Friday afternoon " factory engine build and/or an unlucky collection of tolerances will result in a rough revving engine.

On the other hand there's bound to be a few sweet standard 912 engines out there that have a lucky collection of tolerances and the benefit of a factory engine builder who cared.

Engine /gearbox mount condition will have an effect on vibes through to the cabin of course.