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  #46 (permalink)  
Old 07-28-2013, 04:22 PM
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Thats great. Now take it to a engine dyno shop and get it dyno tested.
Setting it all up on the dyno ( timing jettting boost ratio timing under boost etc etc) and finding and correcting all the little things
as well as being able to break it in under controlled conditions will save you time and money.

If the dyno shop is not setup to run the wet marine manifolds, find some old Merc Magnum marine manifolds
Or find a set of shorty style headers that best simulate your marine manifolds.
and run them dry on the dyno, for testing.
It would be real nice to dyno test it using your manifolds on the dyno.
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  #47 (permalink)  
Old 07-29-2013, 04:17 AM
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Unfortunately are dynos for marine V8's rare in Germany...
I do not know anyone.

I will check it (and adjust it) onboard with Lambda sonde and exhaust pyrometer.
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  #48 (permalink)  
Old 09-03-2013, 05:34 AM
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Restart...

Thanks @all for your help, the restart was successfully!
Now the engine will reinstall in my boat and break in for 15-20 hours.

One problem with backfire when I quickly activate the secondaries from idle.
Within the primaries the engine takes the gas snappy.
Carb is 750 Mighty Demon 5402010BC.
Any ideas?

Andreas
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File Type: zip Restart.m4v.zip (1.44 MB, 4 views)
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  #49 (permalink)  
Old 09-03-2013, 05:52 AM
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what cam is in this motor?

spark advance: timing at idle ,,, timing at max mechanical advance.
Boost retard control box?

Carb jetting and accelerator shooter size.
Blower motors need a different timing curve setup.
Low idle timng will cause it to spit and nackfire when you wack the throttle.
Do not wack the throttle open when the blower and engine are cold.
Let it warm up a bit.

Fix the timing.

A out of the box "stock timing curve will not work on this motor.
Blower motors need a ton of timing at idle yet modest timing when under boost @ WOT.
Often the engine runs best with full locked out timing curve with 32 to 36deg BTDC at idle
But then needs less timing @ WOT when under boost * especially on pump gas.
A boost retard box allows this reduction of spark timing under boost.

If you are not going to dyno test this motor first to get the timing and carb jetting right,
then start with modest timing under boost 26 ish deg under Boost and rich carb jetting
76 primary and 88 sec.
Power valve must be boost referenced. Hook up the vacuum line for the extrenal boost reference to the intake manifold

What is the blower pulley drive ratio, engine compression ratio and what fuel used?
you need to start wth modest boost and timing and sneak up on the tune.
The crappier the gas in the tank the more conservative the timing @ WOT and boost ( blower drive ratio)
If you are going to self tune build your self the simple "engine ears" knock listener head phones so you can listen for detonation under boost @ WOT.

post all the final real build specs of this engine.

find yourself a engine dyno shop. It friggin Germany...They make the friggin dynos there.
.

Last edited by F-BIRD'88; 09-03-2013 at 06:18 AM.
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  #50 (permalink)  
Old 09-03-2013, 06:22 AM
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Low idle timing makes it back fire when the throttle is opened, especially when its cold
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Old 09-03-2013, 06:23 AM
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Ok, I will compile all data.

I have the possibility to fine tune with AFR and EGR.
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Old 09-03-2013, 06:28 AM
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AutoSpeed - DIY Detonation Detection - Part 2

easy to build
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Old 09-03-2013, 06:31 AM
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Knock sensor is also built in...
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Old 09-03-2013, 06:32 AM
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does this carb have a external boost reference vacuum line on it?
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Old 09-03-2013, 06:38 AM
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I don't know, where can I find it?
It is a blower carburetor.
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Old 09-03-2013, 06:46 AM
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The supercharged tuneup on a car is a little different that what works on a boat.
On a car, where generally you are only @ WOT running hard at max boost for only a few seconds
at a time
Like a drag race you can run fairly agressive boost and then reduce the timing under boost to stay out of detonation. generous boost retard)

But on a boat that runs hard WOT under boost for a long time ( accross the lake etc)
if you try this the exhaust temps get too high from the retarded timing. Its real hard on the ehxhaust valves.

So.... in order to run hard with timing (little or no boost retard) you need to either go easy on the blower boost or increase the fuel octane.

For extended WOT running on good pump gas you need to find the right ombo if bloer boost and timing under
boost. Generally you wat that timing in the 30 to 32deg range @ WOT so the exhaut valves don;t get too hot.
THat measn the boost you can run is detemined by the fuel octane.
Higher fuel octane can run more boost at X amount of timing.

Lower fuel octane ditctates running less boost. Know the difference.

Short runs @ WOT you can get fairly agresive on boost and depend on timing retard,

long extended WOT running hard you cannot do this for long.

So if you wanto to run it flat out Hard with lots of boost, then put high octane gas in the tank
100+ octane R+M/2 unleaded and or Get a water / methanol system.

In the mean time keep the boost around 5psi, keep the timing reasonable under boost 29-32deg
and keep the carb jetting a bit rich @ WOt 12.5:1 afr or richer 10.5 11.50:1AFR
and use the best available premimum pump gas.
Sneek up on the tuneup.
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  #57 (permalink)  
Old 09-03-2013, 06:47 AM
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Quote:
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I don't know, where can I find it?
It is a blower carburetor.
I give up...........
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Old 09-03-2013, 06:49 AM
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what is the pulley diameters?
what cam?
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Old 09-03-2013, 06:54 AM
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Quote:
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I don't know, where can I find it?
It is a blower carburetor.
If you cannot identify the boost reference source on this carb then you need a pro
to dial this in for you. it is either on the side of the carb body


or on the carb base or on the carb primary metering block.
Not all "blower carbs" have a boost referenced power valve.
If it does not then install a 10.5" rated primary power valve.
If it does then hook that up to the intake manifold below the supercharger
so it reads and reacts to blower boost.
Do not run under boost until you get this figured out.
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Old 09-03-2013, 06:57 AM
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often the available gasoline at Marina s is not that good (octane)
keep that in mind. Crap gas is not your friend.
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