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Search found 594 matches

by BCjohnny
Sat Jul 11, 2020 4:47 am
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

brentry Thanks, couple of clarifications from the second graph ...... Total weight for steel mass weight is 2523.19 lbs @ 24" OD x 20" L Acceleration rate is 4000 rpm spread over 9.46 secs = 423 rpm per sec gain 'Total Gear Reduction' ratio is 2.1 So, is it simply a question of dividing the mass we...
by BCjohnny
Fri Jul 10, 2020 5:46 am
Forum: Engine Tech
Topic: Shortening valve springs
Replies: 13
Views: 680

Re: Shortening valve springs

I don't think there's much else, on a reasonable budget, you can do other than introducing coolant directly to the process

So maybe adding a fixture to some kind of unloved or obsolete 'wet grinder' might be the way to go
by BCjohnny
Fri Jul 10, 2020 4:53 am
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

Interestingly the subject of flywheel 'weight' has not been addressed, unless I've missed it, so I've had a look around at other diyers musings This guy kind of echoes what I've said Every few years I get the urge to build an inertia dyno for testing engines. So it’s cold out and my brain is wanderi...
by BCjohnny
Fri Jul 10, 2020 4:29 am
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

MOI = 'Moment of Inertia' I've used PMI, which is possibly technically incorrect, and is an abbreviation of 'Polar Moment of Inertia' But we're all referencing the same phenomenon Get a foot long piece of heavy rope and swing it above your head in circles, now get a twenty foot piece and do the same...
by BCjohnny
Wed Jul 08, 2020 3:53 am
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

Stan Weiss Yes sorry misread, it was late and I'd had a couple of apple based beverages ......... but no excuse Even at 12" r / 24" D, 335 lbs seems shy, in as much as : I've not seriously researched inertia dynos, as I'm not building one, but am aware of the inertial effects relative to what I'm d...
by BCjohnny
Tue Jul 07, 2020 7:53 pm
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

Not wishing to argue, and not run the maths (I'm not building an inertia dyno), but I'd imagine if using a solid steel disc you'd be looking well in excess of 1000 lbs at 12" dia Apologies if I'm wrong but 335 lbs @ 12" seems shy, to me ? Empirically : IIRC a Dynojet car inertia roller dyno has a dr...
by BCjohnny
Tue Jul 07, 2020 1:59 pm
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

Powertrip You'll be spinning a helluva lot of weight relatively to keep the rpm gain reasonable, obviously depending on the torque / horsepower curve of the V8 your testing That's why it's more practical use brakes with diminishing load to control rpm gain rather than using pure inertia The big ine...
by BCjohnny
Tue Jul 07, 2020 4:01 am
Forum: Engine Tech
Topic: Steel Main cap material
Replies: 25
Views: 880

Re: Steel Main cap material

I have seen the two extra studs/bolts inclined at about 10 degrees, is this worth it ? - top wack of the motor will be about 120BHP....
For the amount of work you're investing anyway it's not going to hurt anything ..... although I doubt it's absolutely necessary

Good luck with it all
by BCjohnny
Tue Jul 07, 2020 3:40 am
Forum: Engine Tech
Topic: Homemade Engine Dyno
Replies: 62
Views: 2137

Re: Homemade Engine Dyno

Not sure if the comment was directed at me, but ...... 'step testing' was the most common method used until the advent of computer controlled 'sweep testing' on brake dynos It still has it's uses when ignition and fuel mapping I only mention it in this context as a computer controlled sweep control ...
by BCjohnny
Mon Jul 06, 2020 5:06 am
Forum: Engine Tech
Topic: 302 Clevo 2V Heads with undersized valve guides
Replies: 10
Views: 377

Re: 302 Clevo 2V Heads with undersized valve guides

...... just a comment - the cleveland valves seem to be some of the worst wearing valves on the stems that i have ever seen ......
Function of the compound valve angles and inline follower location ?
by BCjohnny
Mon Jul 06, 2020 5:03 am
Forum: Engine Tech
Topic: 302 Clevo 2V Heads with undersized valve guides
Replies: 10
Views: 377

Re: 302 Clevo 2V Heads with undersized valve guides

Almost thirty years ago I went to the liquidation auction of a cylinder head rebuilding company ..... one of the items was the 'machine' that reduced valve stem diameter so the valves could be re-used in undersized guides It resembled a glorified horizontal belt sander, even in my callow youthfulnes...
by BCjohnny
Mon Jul 06, 2020 4:49 am
Forum: Engine Tech
Topic: Dart SHP 351 main studs
Replies: 7
Views: 262

Re: Dart SHP 351 main studs

There are a great many other variables that affect the torque setting other than just diameter and material, in fact it's almost a whole science Thread design & engagement, effective clamping length, surface finish, even type of coating etc etc Hence 'torque' is often a poor metric for tightening a ...
by BCjohnny
Sun Jul 05, 2020 6:19 pm
Forum: Engine Tech
Topic: Valve job with stones
Replies: 29
Views: 1010

Re: Valve job with stones

I don't 'lap' the valve into the seat ...... not in the conventional sense most here would regard as, anyway ......
by BCjohnny
Sun Jul 05, 2020 2:06 pm
Forum: Engine Tech
Topic: Valve job with stones
Replies: 29
Views: 1010

Re: Valve job with stones

I always use a bounce spring, and put light pressure to 'kiss' the seat and get back out fast .... you will have to do this several times to bring the seat or angles in Not using a spring can be a recipe for disaster, and can get you into trouble fast .... especially when learning the ropes Be caref...
by BCjohnny
Sun Jul 05, 2020 9:03 am
Forum: Engine Tech
Topic: Steel Main cap material
Replies: 25
Views: 880

Re: Steel Main cap material

Almost any HRS structural grade will do, ask a local flame cutting shop for offcuts, they go in the scrap usually If you're jobbing all the machine work out the actual cost of the steel is infinitesimal compared to all the other costs, so EN8 might make you fell better If they're made accurately eno...