[jlm]

I've compiled some info from my spare engine and since questions arise, thought I would put them in one place: (maybe this should be a sticky?)

Block:
bore: 77mm (3.03"), piston area: 46.5 sq cm,
stroke: 85.8mm (3.380") (from the Mullet link to Tridec; not personally measured)
displacement per cylinder: 399 cc (1600cc total)
bore-to-bore centerline: 85.34mm (3.36"), web between bores: .330"
rod length: 130mm (5.11") (eye-center to eye-center)
Rod/Stroke ratio: 1.53
deck height: -3.6mm (-.145") piston is below deck surface;
head gasket: .025"( compressed)
piston: flat with .020 depression to 1/2" of perimeter


(comment: a 1mm ovebore gives 1640cc, about 40cc increase and recuces the web to about .290".)

Head:
intake ports: 1.675" x .85"
exhaust ports: 1.348" x .8"
intake valve: 30.2mm (1.189"), throat below seat: 25.9mm (1.02")
exhaust valve: 23.3mm (.918"), throat below seat: 18.8mm (.74")
rocker ratio: intake 1.65:1; exhaust 1.43:1

cam: base circle 1.185" dia
lobe lift: intake .202", exhaust: .217"
valve lift: intake .333" exhaust: .310"

(PROMINI cam: base circle 1.145" dia intake, 1.132 dia exhaust)
lobe lift: intake .228", exhaust: .240"
valve lift: intake .378" exhaust: .343")

valve adjusters are hydraulic piston, located in the rocker, dia .47"
cam followers are rollers

header ports: 1.366" x .975" (Supersprint is 1.60" x 1.05")
header primaries: 1.36" (Supersprint is 1.63")
header secondaries, Supersprint is 1-3/4"
header collector: 2.3" (Supersprint is 2.5"")

intake runners:
-valve back to flange: 3.5"/4.6" (bottom of port/top of port);
-intake flange to manifold interior plenum: 4.0"/4.5"
total, plenum to valve: 7.5" along port bottom, 9.1" along port roof.

exhaust runners:
-valve back to flange: 2.6"/3.45"

[obehave]

Cam durations?
Great to have all this in one spot.
Thanks

[Humourl3ss]

Good post. I'm just starting to grok the particulars of engine specs; nice to see something that's especially relevant.

-CW

[jlm]

I gave up trying to measure cam duration since it is tough with the hydraulic lash adjusters. When I get my head back, I may give it another go.

[stryder]

Interesting stuff, I'm not really inclined to make it a sticky, because stickies tend to clutter up the view and more people complain that there's too many stickies then something isn't a sticky..

On the other hand, maybe it could get compiled into the technical info or an FAQ, I'll check on that happening.

[obehave]

Quote: Originally Posted by jlm

I gave up trying to measure cam duration since it is tough with the hydraulic lash adjusters. When I get my head back, I may give it another go.

Didn't think about having to measure it, not a simple thing to do.
I was thinking you had them from a spec sheet.

Thanks

[Andy@Ross-Tech.com]

Great info, thanks John! Did you measure valve lift or calculate it using the rocker ratios? Were you able to simulate the hydraulic valve lifter actions using springs inside the lifters? I have visions of some crazy oil-plumbed workbench.

[jlm]

I assembled the cam and rockers, held the valve against the rocker with finger pressure (but not compressing the lifter), rotated the cam and measured the valve travel with a dial indicator. that generated the rocker ratio and the total lift. lobe lift you can get by measurig directly on the cam.

duration is hard because the rise rate is so slow on the ramps (so .050" lifter clearance is usually used, hard to get without mechanical lash adjusters), but lobe center spacing would be useful.

all of the measurements were directly measured at my secret lab.

[miniracerX]

Great resource, you wouldn't happen to have the runner lengths for the head and intake would you?

[Paul]

Some basic engine specs from Tritec, for all the Tritec engines (3 of them):

http://www.tritecmotors.com.br/engli...ors/tabela.htm

[jlm]

bump; runner lengths added to post 1

[wmd]

Quote: Originally Posted by obehave

Didn't think about having to measure it, not a simple thing to do.
I was thinking you had them from a spec sheet.
Thanks

From the tech paper on the MINI powertrain that was published by five BMW engine group leaders back in July 2002:

Duration intake/exhaust: 236/243º (zero lash)
Valve Overlap: 20.4º
Intake centerline: 111º
Lobe separation angle: 110º (cam degrees)
Valve angle intake/exhaust: 22º/20º

For comparison the Promini cam has duration 262/262º.

[markjenn]

I see a lot of things in this engine that suggest toughness: relatively long stroke limiting RPM and giving a relatively flat torque curve, cast iron block, hydraulic lifters, and roller rockers. And there have been no bottom end changes for the JCW. This suggests we may have an engine, while not as refined as a Honda 4-banger, that will be very long-lived.

Has anyone heard of any major "hard parts" failures in one of these engines (pistons, crank, etc.). With perhaps half-a-million of these engines in the field, the lack of any issues here is impressive.

- Mark

[olddad]

jlm, is there room to raise the piston pin, or are longer rods impossible?

[jlm]

I don't know for sure; Larry is changing out the rods and will be using his special pistons that will deck .100 higher, and probably have a higher pin location, so it seems likely the R/S ratio can be improved.

[jlm]

olddad: check out Too"s response

[miniracerX]

Quote: Originally Posted by jlm

bump; runner lengths added to post 1

Excellent, thanks...

[olddad]

Doesn't sound like good news for the stock pistons and the pulley reductions. TOO is saying ANY boost increase requires better pistons unless there is perfect mapping. Maybe there has not been enough miles put on these cars to see how the long before the pulleys kill them.

[obehave]

OK, what is TOO's response?

Boost killing engines sounds bad.

[Paul]

Especially if they happen during the JCW warranty period.