Montere luftfilterboks V8 bensin Windy 22. Brannfarlig?

[Maruma]

I en ellers så stille V8 bensin er det mye støy fra forgasser når man drar på litt, kunne da tenkt meg å montere en luftfilterboks ved siden av motoren. Noe sier meg at dette kan bli brannfarlig ved oppstart om motoren skulle gi fra seg et tilbakeslag.

Er det noen som har meninger/erfaring rundt dette?

 

Jeg har tenkt på en luftfilterboks fra Hiace og lage rørtilkobling selv.....

[Bearded Beast]

jaha? hvorfor meir brannfarlig i båt enn i bil?

[DieselDahl]

Jeg har sett luftfiltere stå i brann så du har et poeng der i at det ikke bør være noe brennbart rett før forgasseren. Jeg har vært på noen billøp og på lydsjekken hender det at biler med plenty lyddemping på eksosen blir dømt ut på for mye støy som skyldes innsuget. Hvis du utformer motorlokket som en lyddempet boks kan du nok fjerne mye sjenerende lyd.

[Hakkannen]

Det er mindre brannfarlig om du har luftfilteret i boks på siden av motoren, altså på litt avstand fra forgasseren. Et tilbakeslag gir ikke voldsomt lang stikkflamme, selv om enkelte med filteret rett oppå gasseren har opplevd tilløp til brann i filteret ved kraftige tilbakeslag. Det skal litt til at svake tilbakeslag klarer antenne et luftfilter. Så er større fare med å kjøre standardløsningen sånn sett, selv om slikt hører til sjeldenhetene om tenning og forgasser er riktig.

 

Uansett ville jeg i tillegg til luftfilterboksen ha sørget for en plate mellom boksen og motoren med tanke på at strålevarmen fra motoren gjør at innsugslufta kan blir varm. Kjølig luft er å foretrekke da motoren vil yte bedre og kan man løse slikt billig med en skjermende plate, så hvorfor ikke For hver grad du senker innsugslufta tjener du ca. 0,16% moment/hk, altså senker du innsugstemperaturen med ca. 31,5°C vil motoren får ca. 5% mer moment/hk (kilde: artikkel om trimming av V8 av Torbjørn Lindstrøm)

[Bearded Beast]

mao totalt ubetydelig! Du trenger nå strengt tatt ikkje ha papirfilter i luftfilteret da. Det holder med boksen. Er det slik fatt du ikkje har plass til et heilt ordinært stekepanne type boks?

Redigert 26.Oktober.2013 av Plutonium (see edit history)

[adeneo]

Det er helt sikkert mulig å få til noe for å få mindre lyd fra forgasseren, men det er vel så vidt jeg kan huske første gang jeg har hørt at noen er plaget av lyd fra forgasseren og at denne bråker så mye at det er et problem.
Uansett, K&N lager filtre for båter, med bomullsfiltre, hvorvidt de bråker mindre vet ikke jeg, men det er i hvert fall mer "filter" enn på helt åpne flammedempere.



Benytter muligheten til å sitere litt fra et rundskriv utgitt av U S Department of Transportation

Most boaters driving gasoline powered inboard boats know that there is something on top of the carburetor.
They probably think it's to keep bugs, loose clothing and other airborne objects from being sucked into the engine.
Those who are more knowledgeable may know it is a backfire flame arrester, but don't know how important it is.
Some might even think about taking it off to "let the engine breathe" better and increase speed, even one-tenth of a mile per hour.
On one boat some years back, with a V-6 stern drive, the arrester had been replaced with an automotive paper element air cleaner.
The owner still had the sack from the auto parts store with the sales slip.
There was an engine compartment explosion and ensuing fire. A little girl, who was asleep on cushions under the fore deck, never made it out.
They sued the boat manufacturer, the stern drive manufacturer and even GM [General Motors], which made the basic engine.
They didn't get a dime.

Backfire flame arresters serve a very important safety function. All gasoline engines with carburetors tend to vent fuel vapor after shutdown. lf shut down from high speed, they are hot and will boil off some of the fuel in the float bowl. This vapor goes into the engine compartment and will linger for a while unless taken out by the ventilation blower.
The vapor itself does no harm , as long as there is no source of ignition present. Sources of ignition can be electrical or from a backfire in the engine intake system when it is restarted.
Most of us have heard a backfire. On a boat, flames spouting out of the carburetor can ignite that fuel vapor in the engine compartment.

The operating principle of the flame arrester is to cool and quench the flame front by forcing it to pass between some closely spaced metal elements that act as a heat sink.
Since the engine must take in air without too much restriction, many elements are required with many small spaces between, hence the typical arrester design of a circular shape that is six or more inches in diameter and an inch or more in height. Some form of delayed or late ignition takes place in one of the cylinders at a time when the intake valve is open and the resulting flame ignites the fuel and air vapor in the intake manifold.
The pressure created has to go somewhere, and that's back out through the carburetor or intake system.
With a working flame arrester, only the pressure is released and none of the flame gets out.
A damaged flame arrester is little, if any, better than none at all. The slip of a tool that spreads the metal elements apart, even in one spot, can let that flame pass through.
Damaged arresters should be replaced, and inspection of the arrester should be a part of every commissioning. Occasional careful cleaning with oil and grease dissolvers will keep the engine breathing normally.

A tight metal-to-metal joint is probably the best, with an elastic stop nut used on the hold down stud to make sure it stays tight.
Most two-cycle gasoline engines don't need flame arresters. Such inboard engines are found on personal watercraft and jet boats, basically outboard powerheads coupled to water jet pumps.
Backfire flame arresters and the power heads of such engines are required to pass similar tests to be certified (as an acceptable means of backfire flame control).
This consists of being subjected to a 50-cycle test procedure in which the carburetor, with the arrester installed, is mounted on top of a cylindrical chamber simulating the volume of an intake manifold.
The outside of the carburetor is in another chamber of several cubic feet in volume with a spring-loaded lid.
Both chambers are filled with an explosive mixture of propane and air. The mixture in the chamber below the carburetor is ignited by a spark plug.
The resulting explosion and flame front must not ignite the mixture in the upper chamber.
To complete the test cycle, the mixture in the upper chamber may also be ignited by another spark plug to prove that it was in the explosive range.
There must never be an incident where the upper chamber mixture is ignited as a result of the mixture in the lower chamber.

Federal law requires that inboard gasoline engines be equipped with an acceptable means of backfire flame control (a Coast Guard approved device or one which meets UL IIII or SAE I928). lt's a good safety precaution and one that has prevented a lot of boat fires and saved more than a few lives over the years.

[Maruma]

Takk karer :-)

Grunnen til at jeg spør er jo fordi jeg ikke vil gjøre noe som gir større brannfare, båt er båt og bil er bil. Rundskrivet som du refererer til Adeneo understreker farene.

Støyen plager meg ikke veldig, men å få det stillere er jo fint :-) Jeg skal undersøke litt om hva slags filter som sitter i Hiace boksen, papir er det ikke så vidt jeg kan huske.

Et stekepannefilter har jeg god plass til, men jeg vil tro at en boks vil dempe lyden mere.

Takk for tips og linker alle sammen :-)

[ehrnst]

Når man først er inne på det. Hvordan vasker jeg denne flammedemperen best?

 

Sent from my Lumia 800 using Tapatalk

[Maruma]

Vaske den i bensin er det jeg ville gjort.