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Old 10-30-2013, 04:45 PM   #241
JAWS
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Default Re: Blown 45 build

I wish I had a mill and lathe at home. I am thinking of twin mags. Single drive. Independently and totally adjustable.
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Old 11-01-2013, 01:43 AM   #242
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Default Re: Blown 45 build

Everyone should have an mill and a lathe in his garage. i'm still short of the mill but i'm working on it.

Frenchowl gave me some prints of the internals for an distributor cap for the mag.
If i feel that i got time for that too, that would be really intresting to dig into.
Highest prio is to get this thing up and running
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Old 11-01-2013, 04:20 AM   #243
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Default Re: Blown 45 build

Elffors,
not knowing any thing about mags when I rebuilt mine, I called these guys... http://www.morrismagneto.com/ . Dave and his son answered all of my questions, even some I hadn't thought to ask, they really took the time to make sure I knew what I was doing. Ya might drop them a line about single firing your mag.

BTW, your thread is one of the first ones I opened when we got moved and set back up. Love what your doing and how your doing it...
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Old 11-01-2013, 06:42 AM   #244
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Default Re: Blown 45 build

Yes, this is very interesting thread... I love these old flatheads and the idea of supercharging and tuning them.
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Old 11-01-2013, 07:17 AM   #245
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Default Re: Blown 45 build

Thanks for the kind words!
I already have what morris has to offer in terms of single fire adapters for my mag.
I will run it and expect it work.
But..
If i can make something myself thats not an ugly electronic gizmo, but an mecanical good looking, good working solution. That would be so much more badass in my book.

Nothing is impossible, it just takes more time....
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Old 11-01-2013, 10:43 AM   #246
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Default Re: Blown 45 build

Quote:
Originally Posted by Elffors View Post
If i can make something myself thats not an ugly electronic gizmo, but an mecanical good looking, good working solution. That would be so much more badass in my book.

Nothing is impossible, it just takes more time....
Yeah!! We share taste in literature!
M
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Old 11-01-2013, 11:43 AM   #247
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Quote:
Originally Posted by mads4 View Post
Yeah!! We share taste in literature!
M
I cant read, but share the same philosophy.

My other idea was dual point plated single distributor. Wont do reverse polarity, so there will be wasted spark. It will allow for timing of the second set of plugs. Could be modified to do single fire.

Like I said Im working on it for my cone shovel.
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Old 11-05-2013, 02:38 PM   #248
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Default Re: Blown 45 build

Finally something happens again.
Got the throttle arrangement working. Need an return spring of the proper strenght and some bolts of the proper prettiness, but i kinda like it.

Maybe the wiregrooves in the brasswheels needs to be cut deeper, time will tell.

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Old 11-10-2013, 03:13 PM   #249
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Default Re: Blown 45 build

It feels like there's a light in the end of the tunnel!
Last steps of the 2do list is like ten steps long but there are only 2 major things on it. The rest goes like draw fuel lines or add oil in the charger.

Major isn't so major, it's make an contrapation to hold the magneto in kicking position. Had an idea about that but scraped it after seeing a clever device on youtube. copy paste.

The other is making the SU work without fuelpump.
i Have the SU Hs4 carb and the problem area of it i think is the floatbowl needle being so small that i cant enlarge the fuel inlet enough.
But those carbs where made in Hs6 and Hs8 seizes to, so i will order an needle from one of those carbs and make my carb work with it.

After it makes it's first supercharged noises there will be tons of little stuff to fiddle with til summer so it won't be done by far when fires for the firts time
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Old 11-10-2013, 04:26 PM   #250
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Default Re: Blown 45 build

Hi Elffors, My inlet needles, before on right, after on left, twice the diameter, so 4 times the surface area.




The new one was just a touch sticky so I waisted it in the middle, now perfect...

Patrick
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Old 11-10-2013, 05:05 PM   #251
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Default Re: Blown 45 build

Hmmmm.
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Old 11-11-2013, 02:39 AM   #252
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Default Re: Blown 45 build

Quote:
Originally Posted by thefrenchowl View Post
Hi Elffors, My inlet needles, before on right, after on left, twice the diameter, so 4 times the surface area.




The new one was just a touch sticky so I waisted it in the middle, now perfect...

Patrick
Well that's intresting.
But mine's is a super light piece of hollow plastic with an steel tip. I ain't sure if the original bowl has the capacity to lift an all steel needle. but you got me thinking i new patterns.
What size and make of carb do you use?

Last edited by Elffors; 11-11-2013 at 02:32 PM.
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Old 11-11-2013, 07:44 AM   #253
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Default Re: Blown 45 build

Hi Elffors

Mid seventies S&S MGAL, 47mm throat:



You can see the 1/2 stainless line on the left. I also added an SU float chamber, all empty to increase bowl capacity from 175cc (S&S alone) to 300cc with both. It doesn't lean out after 2 miles flat out. Haven't tried yet to run a 3rd mile on the go!!!

Patrick
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Old 11-11-2013, 02:54 PM   #254
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Default Re: Blown 45 build

That's alot of carb!
But you run methanol and that's like 70% more fuel(?)
does it need more air to burn all that fuel?

Hmm.. i'm thinking that i might have undersized my carb...

Today i shortened the inletpipe for some better chain clearance, draw some oil lines. And ordered an "racing" floatbowl needle
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Old 11-11-2013, 03:28 PM   #255
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Default Re: Blown 45 build

Issue is btu of alcohol to gas. Depending on application will determine, well everything about cfm, fuel volume and rate of consumption.
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Old 11-11-2013, 04:09 PM   #256
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Default Re: Blown 45 build

Fuel usage is very dependant on supercharger, revs, size and ratio...

I did a lot of calcs before hand and while the engine seems happy with them, fuel consumtion is now twice what the calcs said for the amount of air the engine ingests. Real mystery to me!!!

Air to gas weight ratio is about 13 to 1. Air to methanol is supposed to be half that, 6 to 1. From my jets and consumption, it's running now more like 3 to 1...

At Bonneville, it took just over a minute from standing start to crossing the end of mile 2 at 123mph and a bit. On paper, that was 1 liter of methanol needed. I'm using about 2... And my good tuning friend Richard was thinking I was still a bit lean .

Engine at about 5000rpm, charger twice that at 10,000rpm. 500cc per charger rev, so that's 5,000 liters of air ingested per mn. Every time one inlet valve opens, a liter fills one 450cc cylinder plus 100cc combustion chamber = 550cc (CR 5.5 to 1). Don't know what the pumping losses are, hard to know, I never had the engine on a dyno. All my calcs were with 10% losses.

A supercharger certainly makes your engine drinks a whole lot more of whatever you choose to feed it!!!

Patrick
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Old 11-11-2013, 04:45 PM   #257
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Default Re: Blown 45 build

That is true.

From my experience, which is limited, supercharged engines exceed VE. Depending on the chargers rate of compression and size, effectively boosting displacement and compression. This is known. What Ive found is closer to 3 times the fuel consumption with alcohol. It has been similar with gas as well.

I believe its the different atmospheres created above and below the charger. I also believe the sheer velocity of the fuel mix and exhaust moving through the chambers as rpm increases, causes another atmosphere change where a vacuum occurs outside the exhaust valve and port. Similar to scavenging.

Makes me wonder about exhaust configurations.
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Old 11-12-2013, 03:26 PM   #258
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Default Re: Blown 45 build

My only hands on experience from blown engines is my blowthrough carb turbo set up.
In such a case like that the standard carb doesn't present an restriction cause the air forced past the venturi accelerates causing a greater pressure drop across the jet drawing more fuel through the carb.
4 38mm carbs have successfully supported 400bhp on the dyno. And jetting stays almost the same as N/A!

So before this build i read some books about this and they claimed that a similar situation should be present in an drawthrough set up.

i found it a hard to belive cause bigger engines demand bigger carbs than small engines and the carb itself have no idea what ever a big engine is asking for x cfm of air or an small engine assisted by an charger is asking for the same x amount of air?

There where an discussion about this on my swedish build thread but since drawthrough charger set ups is virtually non existent in sweden i decided to go by the books an stay with the 38mm size carb i had before

My question to frenchowl where if he had to go extra large in carb size cause of his use of methanol or did he needed that size anyway cause of the charger application?

Quote:
Originally Posted by JAWS View Post
Issue is btu of alcohol to gas. Depending on application will determine, well everything about cfm, fuel volume and rate of consumption.
Quote:
Originally Posted by thefrenchowl View Post
Fuel usage is very dependant on supercharger, revs, size and ratio...

I did a lot of calcs before hand and while the engine seems happy with them, fuel consumtion is now twice what the calcs said for the amount of air the engine ingests. Real mystery to me!!!

Air to gas weight ratio is about 13 to 1. Air to methanol is supposed to be half that, 6 to 1. From my jets and consumption, it's running now more like 3 to 1...

At Bonneville, it took just over a minute from standing start to crossing the end of mile 2 at 123mph and a bit. On paper, that was 1 liter of methanol needed. I'm using about 2... And my good tuning friend Richard was thinking I was still a bit lean .

Engine at about 5000rpm, charger twice that at 10,000rpm. 500cc per charger rev, so that's 5,000 liters of air ingested per mn. Every time one inlet valve opens, a liter fills one 450cc cylinder plus 100cc combustion chamber = 550cc (CR 5.5 to 1). Don't know what the pumping losses are, hard to know, I never had the engine on a dyno. All my calcs were with 10% losses.

A supercharger certainly makes your engine drinks a whole lot more of whatever you choose to feed it!!!

Patrick
Quote:
Originally Posted by JAWS View Post
That is true.

From my experience, which is limited, supercharged engines exceed VE. Depending on the chargers rate of compression and size, effectively boosting displacement and compression. This is known. What Ive found is closer to 3 times the fuel consumption with alcohol. It has been similar with gas as well.

I believe its the different atmospheres created above and below the charger. I also believe the sheer velocity of the fuel mix and exhaust moving through the chambers as rpm increases, causes another atmosphere change where a vacuum occurs outside the exhaust valve and port. Similar to scavenging.

Makes me wonder about exhaust configurations.
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Old 11-12-2013, 06:00 PM   #259
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Default Re: Blown 45 build

I know this much all cfm seems to do is limit rpm potential on a blown engine.


Simple test I found is using a vac gauge below the carb. At WOT there should be 0 vac if cfm is adequate. If there is a reading, then there is a restriction to the pressures trying to equalize. This holds true on na setups as well.

Opposite as well. If 0 is before WOT.

Bear in mind I am not talking about fuel mixes here.
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Old 11-12-2013, 06:41 PM   #260
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Default Re: Blown 45 build

Hi Elfors, Jaws...

Can't really say I designed the bike with another carb 1st.

What happened was I got that carb as a gas carb on a 74 ci 1967 CH engine... Way too big for the bike so it ended up on the shelves for a long while...

Then I acquired an XLRTT, same again, 74ci, but with huge domed Dytch pistons. Wouldn't rev past 2000rpm on gas... So decided to mod the carb to methanol, n.a.

That took about 5 years to set up, not cause I'm an idiot, just that I did not use the bike that much cause of work loads, maybe 2 or 3 times a year...

Eventually, got fed up of the methanol palava on the XLRTT, castor oil, flushing oil... Put it back to std with a 38mm race Tilly fed with regular gas.

Big carb back on the shelves until I decided to build the Bonneville bike. When I received the Ansin AMR500 supercharger, the ports did impress me, about 2" x 2" square... seemed to be asking for a big carb to hand out there...

MGAL off the shelves and on the bike...

Patrick
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