View Full Version : Aluminium manifolder og afgangsknæ
Miss Mancini
21-12-2008, 19:14
Mange saltvandskølede udstødningssystemer er oftest i støbejern og efter en grum tid i favnen på det hidsige saltvand, så sker det at de gennemtærer eller "skaller", så de blokerer kølekanalerne.
Udover forskellen på støbejern og aluminium, er der også en stor vægtmæssigbesparelse....Her er lidt kolde facts, som jeg foretog i fredags:
Eet komplet sæt manifolder og afgangsknæ ( V8 ) i støbejern vejer 65 kg.
Eet komplet sæt manifolder og afgangsknæ ( V8 ) i aluminium vejer 25 kg.
Er der nogen der har erfaring med et saltvandskølet aluminium udstødningssystem ?
Der findes/fandtes alu systemer til visse V8ère men de var beregnet til lukket kølesystem eller i det mindste både der sejler i rent ferskvand - i saltvand med et åbent kølesystem forsvinder de hurtigt der er flere tråde om disse alu manifolde på iboats.com
lille tut
21-12-2008, 20:35
Jeg kører med EMI THUNTER som er alu med saltvands køling idet min ferskvands køling er halv.
Der er garanti for gennemtæring de første 5år i saltvand/skriver de:D
Købte alu for at spare på vægten plus lysningen er større=mere moment-.ljjj-
Lyder spændende - har kun læst om slumanifolde på iboat men aldrig selv haft en
Det er jo en klar fordel at vægten er mindre
Stainless marine laver også udstødningsmanifolder af aluminium med rustfri stål albuer.
Her er et sæt til en small block V8: http://www.stainlessmarine.com/myProducts.CFM?CFID=6157968&CFTOKEN=a2e58b5d9b5b2aec-B2EED222-3048-2D85-1B9C07E80D41335D&parentcategoryid=43%7CSB%20Manifold%20KITS&productID=19&showDetail=1&categoryID=43|SB%20Manifold%20KITS&vendoridtodisplay=0&filterFor=&collection=
Jeg mener også at der er 5 års garanti på dem selv ved brug i saltvand, men kunne ikke lige finde noget om det på deres hjemmeside. Der er mange som bruger dem på OSO (offshoreonly.com) og de lader til at holde bedre end standard støbejern.
De må behandle dem på en eller anden måde siden de holder så godt.
Skibsbyggeren.
22-12-2008, 00:08
Det må være en alu-legering - ren aluminium ville tære op. Alle Offshorekonstruktioner er beskyttet mod tæring med anoder af aluminium. Vi har for et halvt år siden leveret plies (pæle) og transisionspieces (overgangstykker) til havvindmølleparken "Horns Rev II. Disse 92 overgangstykker af 100 T stykket, var alle udrustet med alu-anoder. Aluminiumsanoder har ca. dobbelt så lang levetid som zinkanoder i salt og brakvand.
Se evt. www.bladt.dk for at se billeder af omtalta anoder.
Her er der en beskrivelse af Stainless marines aluminiums manifold:
The Stainless Marine Hi-Torque exhaust manifold is the most sophisticated on the market. Unlike the run-of-the-mill cast aluminum manifold, the Hi-Torque is a hybrid, utilizing a casting where it is needed, and metal fabrication where desirable. We probably have two or three times the man-hours in each manifold than the cast guys, but it pays off for the boater in the long run. We cast the runner portion of the manifold in A356 aluminum. A356 is best castable alloy in strength vs. corrosion numbers. We then draw form the cooling jackets of 5052 aluminum, zero temper. 5052 is the best alloy of noncorrosive cold-formable aluminum sheet.
Before assembly, we inspect the cast runner inside and out. It is a simple 2 dimensional shape, like the exhaust manifold on a car or truck. After it passes inspection, we assemble it with the half-shell cooling jackets and water fittings in a fixture, and tack weld it together. We have a 500 degree oven to heat the manifold assembly before welding. When the manifold reaches 500 degrees, the jackets are welded together around the seam. The entire assembly cools together, minimizing stress.
We machine the welded assembly, pneumatically test it, chemically treat it and send it to powdercoat. When it comes back, it is ready for use. What is the difference between our method and everyone elses? Even Superman can’t look into the innards of a 3 dimension cast exhaust manifold, full of lost cores and such. Might be perfect. Might not. Guess who is going to find out. We have the only answer for that problem. We made the inside of the manifold two and one half times as thick as the outside cooling jacket. When it dies, and it will, it promises to tinkle in you bilge, AND NOT IN YOUR ENGINE! We have been using this method for 17 years, and in all that time, we have seen exactly ONE manifold where the inside failed before the cooling jacket.
We were the first company with a five year limited warranty (also the first with 36 and 50 month warranties). The other guys had to follow, but they weren’t happy about it. Another comparison that we face is the occasional ‘new guy’ who gets the great idea of building an all-stainless manifold. Guess what! This company was founded 27 years ago making stainless steel manifolds. One of the great metallurgical lessons of all time! Fabricated stainless steel does not like to see 1400 degree exhaust gasses. Hot-cold-hot-cold-break. Stainless steel is a great material for risers. The aluminum water cooled manifold soaks up some of the 1400 degree heat, and delivers it to the stainless steel riser at a manageable 700-800 degrees F.
Another lesson that we learned the hard way has to do with corrosion. We have very few failures during the warranty period. When a manifold fails, we replace it and cut the old one open for a post-mortem. One thing that confused us was the fact that some of the best cared for, best looking manifolds had the most severe damage. I went to a seminar at the IBEX show in Ft. Lauderdale a couple of years ago, conducted by Ward Eshelman, who is the guru of electrolytic corrosion. After the seminar, I stayed and spoke to Ward about our situation. He explained the following: Standard equipment at that time was sacrificial anode (zinc) for each manifold. A manifold sitting full of salt water with a zinc to protect is a happy situation. If you are a careful owner, or a fresh water boater, or both, and flush the engine after every use, the manifold now sits full of fresh water. The zinc changes its name from anode to cathode, and now the manifold is protecting the zinc! We deleted the zinc and changed the water fittings from hard anodized aluminum to a space age fiberglass reinforced plastic. There is a fair chance that the current Stainless Marine manifolds could outlive your boat!
Købte alu for at spare på vægten plus lysningen er større=mere moment-.ljjj-
Kan du mærke forbedringen i praksis ? Har du fået større topfart ?
lille tut
22-12-2008, 16:54
Må være svar skyldig satte det org duo på samme vinter så hvad der har givet og hvor meget til hver???? men den er god til at nå max rpm hurtigt og planer hurtigt.
Igen jeg kører med F-5 props og har 4800 rpm med fri udblæsning så der er træk nok i snoren hvis man lukker op:yoyo:
Ang top ligger den på 53 efter loggen den gik 48 med sx og gamle manifolder
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