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Re: Crankshaft experiment

Posted: Fri Oct 28, 2016 3:22 am
by koncretekid
Jack,
You mentioned there would be a lot of overlap in the valve timing to run over 7,000. Of course with a blower, you might not need as much. But with a normally aspirated motor, how much would be too much? The reason I ask is because I increased my overlap this year from about 66º at .040" lift to about 80º as well as adding about .050" more lift on the exhaust valve (higher ratio rocker arm). I had to jet down for both Loring, ME and Bonneville, and went .5mph slower at each event. Have I gone too far?

Also I'm using a lobe centers of 110º intake and 106º exhaust (single cam of course) with durations over 290º. There are not a lot of cam options out there unless I get a custom one made. I can change the lobe centers with my 5 keyway crank pinion.

Any ideas on which way to go would be appreciated.

Tom

Re: Crankshaft experiment

Posted: Fri Oct 28, 2016 6:20 am
by Jack Gifford
I'm not much help to you with N/A single-cylinder engines. Your need to jet down certainly appears that you "went too far" with overlap. I've come to depend on Dyno2000 simulator software for multi-cylinder engines; are there any simulators available for what you're doing?

Re: Crankshaft experiment

Posted: Mon Jan 09, 2017 6:21 am
by Jack Gifford
hemi_four_jan17.JPG
Not ready for dyno yet. Hoped to fire it up in 2016 but didn't quite make it. I was finally ready to try it December 31st- it fired up a few times on gasoline primer, but with zero bottom-end oil pressure showing I quit before alcohol flowed, so didn't hear it actually "run" more than a few seconds. Fixing the oiling was straightforward. But now it's refusing to light-off, and I'm looking at the magneto possibly being insufficient. Cranking speed isn't very fast with 12.5:1 compression ratio.

Re: Crankshaft experiment

Posted: Tue Jan 10, 2017 11:02 pm
by skippy
Jack Gifford wrote: the magneto possibly being insufficient. Cranking speed isn't very fast with 12.5:1 compression ratio
You would want a strong magneto to get enough voltage at slow speeds to overcome the resistance of 12.5:1 compression and being advanced as well.

Re: Crankshaft experiment

Posted: Wed Jan 11, 2017 8:49 am
by Jack Gifford
It's askiing a lot of a magneto to perform well at 10,000 RPM and also down at cranking speeds. So I've modified the magneto wiring to allow externally switching it to operate as a traditional points/coil/battery system during starting. After it's proven I'll replace the switch with a relay driven from the starter button.

Re: Crankshaft experiment

Posted: Tue Mar 07, 2017 6:32 am
by Jack Gifford
I was having trouble getting the fuel system close enough to keep the engine running on methanol. Finally got it to run steadily at about 3,000 RPM for 20 seconds or so today;.. prior to the explosion! The distorted piece of 3/8" 6061 was formerly the bottom of the blower manifold- wasn't intended to be a "burst panel", but might have served that purpose. Don't know yet about damage to engine or blower. In any case, this will significantly delay the project.

I can only guess at the cause- perhaps too lean, since it was running on only the hat nozzles. I had temporarily blocked the port nozzle delivery so I could check that the popoff valve was functioning.

Re: Crankshaft experiment

Posted: Tue Mar 07, 2017 7:10 am
by Barry Creary
It must be disappointing for you Jack :roll: :uhu

Re: Crankshaft experiment

Posted: Tue Mar 07, 2017 11:18 am
by beat
Hmmmm <201 <201

this means, as the blower blows itself up . right ?

was it a pneumatic force ore a mechanical part that cames across :?:
:shock:

Re: Crankshaft experiment

Posted: Wed Mar 08, 2017 7:42 am
by Jack Gifford
I won't know how disappointing until I assess the condition of the blower and engine.
Beat- it was an explosive force! Luckily I was wearing mickey mouse ears, but the blast still hurt my ears. I had to scramble to extinguish a dozen fuel/oil fires. Although it blew out the furnace and scrambled stuff on shelves, I'm lucky it didn't break any windows.

Hopefully I'll learn something from it. Talked to the dyno shop today to explain that there will be some delay. The guy who does tuning of blown-alky engines was sure that my setup was much too lean. He feels that the engine software I use "loses touch with reality" in this case- a huge blower on a tiny engine.

Re: Crankshaft experiment

Posted: Thu Mar 09, 2017 9:25 am
by b50root
This is sooo intresting. Keep on sharing.

A video when it runs would be nice.

Rickard

Re: Crankshaft experiment

Posted: Fri Mar 10, 2017 6:45 am
by Jack Gifford
b50root wrote: ... when it RUNS would be nice...
:mrgreen: :mrgreen: :mrgreen:

The explosion may have been merely a "symptom" of a "torched" engine due to extremely lean running. Cranking compression is way low, so it's got to come all apart for examination. Don't hold your breath... :cry:

Re: Crankshaft experiment

Posted: Fri Mar 10, 2017 8:55 pm
by beat
Jack Gifford wrote:due to extremely lean running.
any values, any methods of measuring available ?

beat <017

Re: Crankshaft experiment

Posted: Sat Mar 11, 2017 6:49 am
by Jack Gifford
Beat- no, nothing for measuring air/fuel ratio. I've provided bungs in the headers for thermocouples to measure temperatures during dyno testing, but I don't own any thermocouples or readouts. I was at fault for not being more alert during the brief running. I should have noticed more quickly that it wasn't running in the typical manner of a non-loaded alky engine- unsteady, loping, and misting a slight "fog" of unburnt alcohol. Instead, speed was very steady and exhaust note was "flat" rather than "sharp and crackling".

Re: Crankshaft experiment

Posted: Sat Mar 11, 2017 10:49 am
by stew79
good reply to beats question, its not about numbers on a display, but the sound and feel. (with the odd explosion as well!) with so many variables all going on at the same time i think it will just take patience and good luck to arrive at the right setting for every thing. then perhaps you could use a lambda sensor to see what the mixture is. but as its not been made for "steady cruising along" any readings will be irrelevant. i think to monitor egt would be the best way to protect the engine from valve /piston damage, but you would need to have an upper temp reading to keep below. 700 deg c ?
stew
ps i cant help thinking that fixed timing at max advance, might have contributed to the back fire.

Re: Crankshaft experiment

Posted: Thu Mar 30, 2017 6:15 am
by Jack Gifford
Damage isn't as bad as it could have been. Can't find any cracks in block or head, crank is straight, pistons & rods are fine, cylinder walls only have some very shallow scratches, blower appears to be unharmed. One small torched spot in cylinder head is being repaired, and I'm machining for new valve seats in that cylinder (seats lost their press fit). Re-constructing the blower manifold will be a challenge, but it's do-able.
The next time around I'll first run it naturally-aspirated for awhile to [more safely] iron out the general setup.

Re: Crankshaft experiment

Posted: Fri Mar 31, 2017 1:22 pm
by Mark Cook
What material are you using for the valve seats Jack?

Re: Crankshaft experiment

Posted: Sat Apr 01, 2017 5:22 am
by Jack Gifford
Valve seats are either manganese bronze or silicon bronze- need to look through my notes.

Edit: seats are manganese bronze- "Alloy 25" per supplier.

Discovered a couple of days ago, a major contribution to the incident. I meant to go larger on hat nozzles than the Hilborn #20's I used in my last blown-alky engine, so I bought #24's. But I mistakenly got Enderle 24's which are equivalent to Hilborn #9 nozzles... ouch!!! :shock:

Re: Crankshaft experiment

Posted: Thu May 18, 2017 5:30 am
by Jack Gifford
Been awhile since my last post. Pretty much found answers for everything. Been busy re-constructing stuff. Still working with the head- more than a couple valve seats lost their press fit, and a number of surfaces "moved around". Shortblock is back together. Blower manifold is re-done, this time with an SFI burst panel and four(!) popoff valves. And the top machined to accept the injector, for initial naturally-aspirated test-running this time.

Re: Crankshaft experiment

Posted: Thu May 18, 2017 8:35 pm
by beat
....... and still no measuring of A/F R ore others :?: :?: <201
<939

Re: Crankshaft experiment

Posted: Mon May 22, 2017 5:13 am
by Jack Gifford
No, still no measuring of A/F ratio. I only need to be in the ballpark for test running. And so many errors were identified in the prior setup that I'm confident I'll be okay now. Nevertheless, I'll use caution- run it first unblown to allow unhurried observation of all systems. Then eventually add the blower, but initially drive it much slower- 80% of crank speed vs. the prior 125%.

With fingers crossed... and a new fully-charged 10 pound Halon extinguisher within arms' reach... ;-)

Re: Crankshaft experiment

Posted: Mon May 22, 2017 9:33 am
by minetymenace
Jack Gifford wrote:Halon
:shock:
You yanks really are convinced that global warming is a myth!

Re: Crankshaft experiment

Posted: Mon May 22, 2017 11:30 am
by stew79
global taxing (true name) is the biggest global con ever ! but isnt this going a bit off topic ?
stew

Re: Crankshaft experiment

Posted: Tue May 23, 2017 6:20 am
by Jack Gifford
Minety- my new extinguisher is filled with 100% "reclaimed" Halon. The U.S. complies with the UN's ban on Halon production. Use of existing Halon stock is not banned. The UN declaration makes an exception to allow Halon production for aircraft systems, since no other agent meets all requirements of airliners. Since the aircraft systems are routinely serviced, there is plenty of reclaimed Halon available- albeit at ten times what it cost in the past. I'll gladly spend the extra money for such a desirable home extinguishing agent- efficient suppression (especially of burning liquids), non-toxic, non-contaminating, non-staining, no cleanup required, etc.

Re: Crankshaft experiment

Posted: Tue May 23, 2017 11:47 am
by minetymenace
Yep nothing better for fire extinguishers, in the UK only permitted to be used by aviation, police and anyone with guns (which are also banned). Non-existent extinguishant in civi-street as we recognise it is very very nasty to the environment, as manufacture has ceased, probably best leave the existing stocks for where there is no alternative. I do realise other countries have a more lackadaisical approach to the planet, that was all I was pointing out.....

Can you be <910 in <910 :?:

Re: Crankshaft experiment

Posted: Wed May 24, 2017 12:32 am
by skippy
I live in a hole in the ozone layer and as i am not that young anymore, I know the difference when it comes to getting sunburnt.

Re: Crankshaft experiment

Posted: Wed May 24, 2017 6:21 am
by Jack Gifford
minetymenace wrote: ... other countries have a more lackadaisical approach to the planet...
It seems you're including USA in that? I don't agree- although use of reclaimed Halon is legal here, it's expensive enough to almost totally discourage it. I'm probably one-in-a-thousand who would spend $100+ for 10 lb. of it. And as for actual usage- the 2 1/2 lb. I recently used was the only instance in 40 years of having the extinguisher. [Full disclosure: during my 20 years of competition I did witness a few instances of track personnel giving a small squirt of Halon from a pocket size extinguisher to kill oil/fuel fires]. So... I wouldn't characterize our full compliance with the international ban as "lackadaisical".

As originator of this thread, am I allowed extra freedom to post off-topic? ;-)

Re: Crankshaft experiment

Posted: Sun Aug 13, 2017 4:05 am
by Jack Gifford
After 3 months of delay (life gets in the way of racing), I finally got my son to help (mostly observe) as I fired it up today. I'm a little bit surprised how "mean" it sounds unblown- very good throttle response. Only about 30 seconds running, but didn't hear/see anything out of line. I'll do some checking (compression, leakdown, etc.), then some more running (to get up-to-temperature to check coolant flow, etc.) before bolting the blower back onto it.

Re: Crankshaft experiment

Posted: Mon Aug 28, 2017 6:29 pm
by hwan
Fascinated by the valve seats coming loose - bad fit, or something to do with the cylinder pressures?

Wots up with CO2 in the extinguisher - just as effective in a closed space - and just as lethal if you happen to be in the closed space :grin:

Ask the Texan's if they believe in global warming ?

At least you are not burning hydocarbon ...

Re: Crankshaft experiment

Posted: Mon Aug 28, 2017 11:43 pm
by skippy
CO2 is the best way to stop a runaway diesel engine.

Re: Crankshaft experiment

Posted: Tue Aug 29, 2017 6:30 am
by Jack Gifford
hwan wrote: ... Fascinated by the valve seats coming loose - bad fit, or something to do with the cylinder pressures?...
The explosion was very severe- loss of the .006"-,007" press fit of some valve seats is not unexpected, especially in an aluminum head cast about 55 years ago- not nearly the strength of today's high-strength alloys.

Re: Crankshaft experiment

Posted: Wed Aug 30, 2017 11:59 am
by hwan
So the explosion was in the cylinder and not in the Blower/Inlet ...

I would imagine that unlike centrifugal blowers, the peak pressures in the inlet system of a p/d supercharger can reach high values, even in normal running - hence the blow-off/safety-valve requirement.

Without a positive method of pressure release, inlet system pressures could reach explosive values - particularly with a lean mixture pop-back igniting any incoming mixture ... ?
However you are running fuel injection - direct or into the inlet ports.

I'm thinking out loud with the above comments, really ..... you appear certain(ish) that it was a lean mixture which caused the damage.
I'm wondering about possible inlet explosions with a suck-through carb'ed set-up - and the best design of pressure relief valve (i currently only have P. Irvings book, for info).

Interesting comment about valve seat 'fits' - didn't realize it could be an issue.

Is there any decent info out there about sizing positive displacement superchargers ??

Re: Crankshaft experiment

Posted: Thu Aug 31, 2017 6:33 am
by Jack Gifford
Thanks for your interest. I'll attempt to respond to some of your comments.
I have to assume that the intake valve was open at that instant, so the site of the explosion was the entire intake tract.
A single spring-loaded "pop off" valve was in place, but was too small to alleviate the explosion's pressure. However, I have experienced these valves doing a good job of preventing damage during "routine" incidents (small "pops"), such as too much spark advance during cold weather starting, etc. (I now have four pop-off valves and an SFI burst panel in the manifold).
Fuel is injected both in the "hat" and to individual port nozzles, so, yes, their is a potential for a very explosive intake mixture.
A burst panel is as good as can be done for safety. Beyond that, sacrificial blower studs (hollow aluminum) and blower restraints (required by all sanctioning groups) serve to prevent the engine being a "bomb" and injuring people.
I don't know where to refer you for blower sizing and drive ratio. Personally I've just taken a common sense approach to a starting point- deliver X-amount more fuel/air mixture then the engine would ingest at 100% volumetric efficiency, with X being an educated guess. Then observe boost pressure and adjust drive ratio accordingly.

Re: Crankshaft experiment

Posted: Thu Aug 31, 2017 11:05 am
by hwan
You may guess i'm trying supercharging for the first time - something to try before i die.

Spurred on by a supercharged B25 i was watching the last weekend - boy was it LOUD (+128 dB) - suggesting either the cam overlap or general timing is very wrong as it was way louder than HOBBIT (twin 750 commando+twin superchargers - UK record holder - sub 9s run on s***y track) on the same sound meter/distance away.

However, when the B25 behaves itself, it can do some very respectable runs. It had a very short inlet manifold (contrary to all opinion?), but two safety valves ...
Maybe he was breaking up the excess pressure pulses so problematic on a single, via the safety valves ????

My current concern is the AMR500 I've bought, is too big for the 350 its going on...... :roll:

Re: Crankshaft experiment

Posted: Thu Aug 31, 2017 1:27 pm
by minetymenace
hwan wrote:i'm trying supercharging for the first time - something to try before i die
Oh Yes! :cool: <096

Re: Crankshaft experiment

Posted: Fri Sep 01, 2017 5:56 am
by Jack Gifford
hwan wrote: ... the AMR500 I've bought, is too big for the 350 its going on...
I don't know that blower. Can't you simply drive it as slowly as needed? I'll be using a billet 14-71 (511 c.i.) on my 182 c.i. four cylinder, drive ratio yet to be determined- but significantly under 1:1.

Re: Crankshaft experiment

Posted: Fri Sep 01, 2017 9:49 am
by hwan
Jack - that what i'm planning - under driving it - hence my request for info really......

I presume, a lobed compressor will have some leakage at lower RPM - hit a 'sweet' operating spot somewhere around mid rpm, then go inefficient again at higher rpm.
Talking to an old boy racing a ALLARD (lobed blower) blown MG TA last weekend - he gets max torque, just off idle with a tapering off of boost pressure as rpm increases - smokes his tires or wrecks his gearbox, but he just loves the initial acceleration.

I liked the centrifugal blower i saw on a CR500 @ Bonneville last year - simply 1/2 a Turbo, mechanically driven 10:1 off the crankshaft. Minimal boost at low rpm, with increasing boost as rpm goes up.
Seemed (at the time) to match four-stroke engine requirements - particularly a side-valve (dont ask!).
Unfortunately its 'not within spirit' of the vintage/classic hill-climb/sprinting rules over here in the UK - the AMR, is cos it looks like an old Shorrocks type blower, so they will accept it.

The one thing i have learned over the (countless) years - if you dont try, you never REALLY know -
So f***-it, i'll try and set up the AMR with minimal boost as a start (gearing + blow-off valve), then work from there .................
Not a BSA in sight, but will report back if/when it starts rolling.

I will now have to listen to COOKY go on about water injection, and pay attention this time ............................

Re: Crankshaft experiment

Posted: Sat Sep 02, 2017 4:47 am
by Jack Gifford
Sounds like a plan. Keep us posted.

Re: Crankshaft experiment

Posted: Wed Sep 06, 2017 12:31 pm
by hwan
Yep, will do.
Am waiting on the blower arriving, already I've realized it may be too big for a 350 :???:

Hmmmm suck through carbs and explosions in manifolds seem to be a common problem on highly tuned drag bikes - hence all the rubber hosing and worm-drive clips i suspect !!!
Also a reason many use V or multi V belt drives if they can, in case of a backfire/explosion the blower tends to 'stall' damaging direct drive systems unless theirs a clutch/shear-pin of some type.....

Despite the massive blower on the B25 drag bike, it has no blow off valve and a low volume inlet tract ???
(Must try posting a pix again)

Re: Crankshaft experiment

Posted: Fri Nov 10, 2017 7:10 am
by Jack Gifford
I've run the engine a few times now- repairs seem to be okay. A little more run-time needed to finish tuning for a reliable idle, before bolting the blower back on. Hope to get it on the engine dyno sometime this winter.

Re: Crankshaft experiment

Posted: Thu Nov 16, 2017 12:06 pm
by koncretekid
Jack,
Good luck on your continued testing and I hope to see you in Loring in July. Any chance of that?
Tom