Holset HX35 Install info on om603

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08-20-2010, 08:53 AM #58

(08-20-2010, 07:15 AM)muuris
(08-20-2010, 06:44 AM)ForcedInduction Yes. I have produced over 50psi backpressure on my engine . . .

There is no data to suggest the 606 should perform differently.
Post a 605/6 dyno with an HY35 and show us how bad it really is.
Come on. Your engine has nothing in common with OM606, except manufacturer and fuel. Besides you've got like 40hp/liter, how can you say anything about not-lacking-power-effects?

I haven't had HY35 in mine, but jeemu has in his. I also have tried various backpressure/boost combos with VNT/VGT. So we might actually know something, when you are stubbornly arguing with jut some loose facts based on another engine. I don't want to dyno when it feels like something is strangling the engine.

(08-20-2010, 06:44 AM)ForcedInduction I know for a fact backpressure isn't a danger on the 606 due to the stock turbo.
With stock turbo the boost peaks 12psi at low rpm and drops to 8psi at high revs. Why is this? Becouse with stock turbo, the backpressure would be too high even with such low boost. How about when its 30-45psi boost and similarly greater backpressure at high revs? Stock 606 doesn't pull hard 5000-6000rpm.

Try it out. I already have. It makes a hell of an ugly noise, the engine dies for few seconds (smokes blue, shakes, no power etc). When this happens under hard acceleration (small gear) it may even stall the engine. After a minute everything is ok and engine runs normally.

Changing exhaust valve springs to stronger ones cures this.

I think we can ALL agree that excess Back-Pressure is a bad thing.

--In fact I can see both F.I.'s point and Muuris's points...

Guess where the issues are, are the Effects of this and how a larger turbo relates to it with Added Boost pressure, and the possible restrictions that 'add up' when using a larger turbo with higher pressures......

IS a 605/606 SO Substantially Different and MORE Sensitive, than --any other engine--with regards to this issue.

Many 'disagreements' between guys seems to relate to this point.
--Are the exhaust-valve-springs 'weaker' (Less poundage) than would normally be expected in the 05/06 engines?

One thing I remember, was one of Jeemu's comments--Of which he was very proud, He was getting only 1.8 bar backpressure (I think thats how much) with three bar boost, so this does seem to be a very important item to choosing a turbo....

Personally I havent got much of a clue-Turbo 'curves' are more complicated than Vacuum-Tube 'curves'-of which I'm aquainted!--Would just love some informed guy--who has tested one--to tell me best turbo to use with OM.606 to give 350BHP and GOOD Drivability!
--There has been debate on HX35, some say way too small housings some say its good....
I dont want to 'waste' 600 quid on a turbo to find its no good! Big Grin

Alastair E