Ultimate city turbo motor

[Glenn_Biscan]

Well it has been suggested in another thread so i thought i would start it off

EL motor, with city turbo inlet and exhaust manifolds, forged internals and a slightly larger turbo

[James]

Its not really an ER if you start with a EL, you should have called the topic "Ultimate Bolt In City Motor" if thats where you wanted to go.

[James]

Hah, I just remembered that guy who came on here ages ago, saying that he had built a dohc head for his city turbo motor on his uncles CNC machine. And that he had it revving to like 11k or something, making some ridiculous power output. If it was real, that would be the ultimate ER engine!

[BOOSTBOY]

Has to be ER...

Billet short stroke crank
Block guard
New bore liners, maximum bore size
black metal bearings
H beam rods, longer than original
forged pistons
w-ringed steal head gasket
ARP fasteners all over

Now the good bit - Find a head from a big bore bike, say a CBR1000RR or the like - something that matches the bore spacing of the city.  Remove all headstuds fromt eh ER block and fill.  Redrill and replace to suit new head.  Water galleries wont be a problem due to the block design of the ER.  Oil galleries will need custom work.  Billet cams to be made to suit the ER rotational dirction.

8.5:1 comp ratio
titanium exhaust manifold
HKS GT-RS turbo
Custom inlet with quad throttles
PWR liquid to air intercooler setup
Motec M880 ECU


Custom twin plate clutch
straight cut dog engagement gear set
1.5way LSD
Billet driveshafts

[James]

Ohhh im loving Boostboys engine, thats a sexy beast.

The cylinders are siamesed and so close together aye, you can hardly get any more bore out of them in the position they are, so my idea if your going for a custom crank anyway, move the cylinders apart, space them to suit whatever dohc head you are fitting, then install new cylinder liners, then go from there, might be able to get a good 1600 or so out of the block then.

[BOOSTBOY]

Isn't the bore spacing equal?  Cant remember now!

[James]

nah the middle two cylinders are siamesed together I think, I can't quite remember either, but I remember looking at the block and going, damn you can only get like a 1mm overbore out of that at the most.

[BOOSTBOY]

ok, well we'll have to keep the standard bore size.  My bike head idea will be limited to whatever bikes had their cam drive at the end of cyl no1, i think alot of them have the cam drive between 2 and 3.

I'd like to play with pneumatic valve actuation too, maybe that can fix the above problem...  ;)

[James]

I have had thoughts along those lines, but I was thinking of hydraulic valve actuation, but now I tihnk about it, air would probably be better, less mass to move around.

Have you put much thought into that idea boostboy? be interesting to hear your ideas if you have.

[BOOSTBOY]

A bit of thought yeah...

Imagine the possabilities!  No camshaft actuation so already there is a parasitic gain.  Then you need some other form of control so you'd have some sort of ECU powered valving sytem for the actuators that could be reprogrammed to suit varying engine conditions.  100% constantly varying valve timeing/duration/lift.  Performance upgrades would be easy, just a simple remap of the ECU.  Endless possibilities.

Now find me valving with fast enough response times and i'll take it further!

[James]

yeah, it does seem relatively simple when you thin about it. Have any of the car manufactures done it? It would really be the ultimate in efficiency and power.
You could run the engine in a miller cycle configuration for light loads and idling, then you could ramp up to a full blow lots of overlap race cam when you step on the gas, it would be like the most versatile piston engine ever.

You could dynamically alter the compression ratio aswell by leaving the intake valve open for a period of time during the up-stroke (miller cylce effct).

So you could run a 7.5:1 for easy starting and idling, then ramp it up to a 15:1 when the revs are high enough, it would be kinda like your engine was turboed, but without a turbo :p

[BOOSTBOY]

Exactly, its has many pluses!  I dont know of anyone that is using it but F1 uses pnematic valve springs - not control though as far as im aware.

I think you'd run into problems with air being a compressible fluid though, especially at the speed's we're talking about.  Maybe some other type of gas could be used that doesn't have the same level of compressibility as air could be used.  Any liquid couldnt be moved fast enough.  I dunno, im no chem eng!

[James]

yeah need a chem eng and fluid dynamics end in the same room!

We should work out some opening times, see how quick you actually need it to work. Based on rpm, lift and how long the intake stroke is.

Just found this quote

"Camless technology is being worked on by all the major automakers but it's got a long way to go before it's going to be feasible. It's extremely difficult to replicate the soft-open soft-close characteristics that a mechanical cam has using electrically driven valves. The functioning engines with these types of setups that I know about are extremely RPM limited. If you rev them, they simply snap the heads off the valves as the slam shut."

Which sound a bit strange, in NASCAR engines, the rocker isnt actually on the cam when the valve shuts, they have profiles that lob the rocker off the cam, that means they snap shut extra fast because its just the spring acting on them, they arent actually touching the cam profile.


Some guys rambling on the topic
http://www.halfbakery.com/idea/Camless_20engine

A diesel engine that actually runs pneumatic valves.
http://www.sti.nasa.gov/tto/Spinoff2004/er_3.html

A dudes thesis on the topic
http://www.me.sc.edu/Research/AARG/Thesis%20Final.pdf

Lotus' Effort
http://www.pistonheads.com/news/article.asp?storyId=7005

These rotary valves are worth a look too
http://www.coatesengine.com/

[BOOSTBOY]

Ok then.

Normal 4 stroke IC engine
Max RPM = 7000rpm  

Therefore:
Valve opens once every 2 crank turns
Valve opens 3500 times per minute
Valve opens 58 times per second

valve is open for say 200deg of a camshaft revolution
Lift is say 8mm

now, 7000rpm crank speed = 117rev per sec
so, one crank revolution takes 0.009sec
therefore, one camshaft revolution takes 0.017sec

at 200deg duration
200/360 = 0.55 = valve open 55% of one cam revolution

so, 0.55 x 0.017 = 0.009s

At 7000rpm and with the above cam specs, the valve is open for 0.009 seconds! Yep, 9 thousandths of a second!  The valve has to open and then shut in that time frame!

:)

[BOOSTBOY]

So other people are thinking about it too!