MR2 turbo er relativt uvanlig i Norge. I usa der de ble produsert og solgt er den langt vanligere. Og der er det viden akseptert at om du overstiger 1 bar ladetrykk på orginal turbo og motor så risikerer du motorproblemer.
Gi meg en 2. gen motor med CT26 og jeg skal klare å ødelegge den helt enkelt bare ved å øke ladetrykket
Det er en kombinasjon av de omstendigheter som oppstår når man øker trykket som tar livet av motoren. Så jeg står fremdeles fast på at 1 bar er øvre sikre grense.
Om du vil kjøre over den sikre grensen er jo opp til hver enkelt. Det eneste som er viden akseptert er at om man vil være på den sikre siden så er det 1 bar som er grensen. Over det så kan det meste skje.. Du kan være heldig og kjøre problemfritt på 1,2 bar.. eller du kan få motorras på samme trykket.
Dette er gamle biler og man har ingen mulighet til å forutsi hva som kan skje da man ikke vet tilstanden på alle involverte komponenter. Så jeg står fremdeles fast på at med helt orginal motor, orginal ct26 og orginal IC og eksos så hadde jeg ikke villet lade noe mer enn 1 bar.
Sier ikke at motoren sprenges når man går over 1 bar, sierbare at risikoen for ødelagte stempelringer, ringlands osv øker betydelig når man kommer over denne "sikre" grensen.
Litt nytting og relevant info:
Maximum stock boost pressure is 10-11psi. With the addition of three simple, inexpensive devices, this can be
safely increased to 15psi for a gain of nearly 10rwhp per additional pound of boost. After doing this, you can expect to be producing approximately 200rwhp. First, you need an accurate boost gauge to
be sure that you are not boosting above 15psi. The stock boost gauge is slow to respond, peaks below 15psi and has no numbers to tell you how high you are boosting. Second, you need to raise the point at which the protective fuel cut feature kicks in from around 12psi to 16 or 17psi.
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The notion that a CT-26 just puts out hot air above 15psi is nothing more than hot air. All turbos produce hot air and the higher the boost the hotter it is. Proper intercooling allows higher boost to be safely used regardless of which turbo is being used to produce it.
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When the boost starts, high air volumes from the turbo push their way forcefully through the intercooler shedding heat before entering the manifold and cooling it as well. The bottom line is that a CT-26 with appropriate intercooling produces very safe, usable boost above 15psi.
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The CT-26 compressor has been found to produce 22psi of boost pressure at 3.5K RPMs if the actuator hose is blocked and the turbo allowed to build maximum boost.
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The real problem with the CT-26 at higher boost levels is that the small turbine housing with twin scrolls to maximize the exhaust energy concentrated on the turbine wheel at low RPMs is actually "chocking" the engine. Once the exhaust system has been opened as far as it will go, the only restriction preventing exhaust from escaping the cylinders is the exhaust valve, the exhaust manifold and the turbine. If two boost gauges are attached to the 3S-GTE, one measuring intake manifold pressure and the other exhaust manifold pressure, what is seen is that at boost levels of around 10psi (what the stock MR2 Turbo was designed to operate at) the boost pressure in the intake manifold and the exhaust manifold are practically equal once the CT-26 spools up. This is a very desirable situation and speaks highly of Toyota's ability to match a turbo to their intended application in the MR2. At 15psi of intake manifold pressure, however, the exhaust manifold pressure climbs to over 20psi. This is not desirable. What is happening is that the exhaust gases are being held back by the turbine and, once that starts to happen, the turbine is unable to extract any additional power from the exhaust to push the compressor harder. The only way to produce more power in this situation is to allow the exhaust gases to move more freely across the turbine. There are several ways to do this: 1) get a larger turbine housing that permits more exhaust to flow across the turbine, 2) get a smaller turbine wheel that allows more exhaust to pass across it or 3) "clip" the existing turbine wheel to allow more exhaust to pass through it.
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Ved å booste over 15 psi på orginal motor, ic og orginal ct26 går vinningen opp i spinningen, samtidig som man øker faren for detonasjoner.
Derfor er 15 psi ansett som den øverste sikre grensen. Alt over dette er egentlig meningsløst om man ikke oppgraderer motoren noe: Intercooler, eksos osv.
Info hentet fra:
http://mrcontrols.com/primers/primers.htm
vel og merke med en oppgradert ct26 eller annen turbo.
