Guest adegnes Posted June 13, 2007 Report Share Posted June 13, 2007 During a recent visit at a local wreckyard, I found a homemade dump valve, it's construction is really simple; Just a a alu housing with two big and one small port (in, out and vacum) and a spring loaded piston with a rubber seal at the bottom. It looks really well made, but... when aplying pressure to the vacum input, there's a small leak out the resirk port (there's no seal on the top of the piston) could it be usable anyways? there is no leak to atmosphere, so the afm's readings will be right, but I'd suppose i'll lose some pressure since it leaks trough the resirk and into the intake pre turbo/post afm. will the bov operate correct? maybe if I try adding a rubber seal (or a o-ring) near the top of the piston...? I'll post a picture of it asap. Quote Link to comment Share on other sites More sharing options...
Guest adegnes Posted June 13, 2007 Report Share Posted June 13, 2007 pics of the dump: Quote Link to comment Share on other sites More sharing options...
Bean Posted June 13, 2007 Report Share Posted June 13, 2007 Does it leak on vacuum as well? (that's a bigger concern...) If it leaks only on boost, and it's very slight, then that's not really going to be an issue since the volume of air being used is so high - the leak is going to be insignificant. If it leaks a fair bit - then you essentially have a "bleed" in the system and the turbo has to work harder for a specific amount of boost... Hard to say for sure without know much about the leak - but it sounds like it'd be fine. Rabin Quote Link to comment Share on other sites More sharing options...
Guest adegnes Posted June 13, 2007 Report Share Posted June 13, 2007 yepp, leaks on vacuum to... I think I'll just have to try it out to find out.... btw, found it in a saab turbo, it was used as a replacement for the original resirk valve Quote Link to comment Share on other sites More sharing options...
Toni Lindroos Posted June 14, 2007 Report Share Posted June 14, 2007 yepp, leaks on vacuum to... I think I'll just have to try it out to find out.... btw, found it in a saab turbo, it was used as a replacement for the original resirk valve You can buy the original Saab/Bosch by-pass valve for ~30 e (Saab p/n 4441895 and Bosch p/n 0 280 142 110, more info). Quote Link to comment Share on other sites More sharing options...
Guest adegnes Posted June 14, 2007 Report Share Posted June 14, 2007 hmm.. I'll try fitting a O-ring near the top of the piston, should seal it of.. Quote Link to comment Share on other sites More sharing options...
norcal505 Posted June 14, 2007 Report Share Posted June 14, 2007 Does it leak on vacuum as well? (that's a bigger concern...) If it leaks only on boost, and it's very slight, then that's not really going to be an issue since the volume of air being used is so high - the leak is going to be insignificant. If it leaks a fair bit - then you essentially have a "bleed" in the system and the turbo has to work harder for a specific amount of boost... Hard to say for sure without know much about the leak - but it sounds like it'd be fine. Rabin btw, adgenes, how much psi are u running?? Quote Link to comment Share on other sites More sharing options...
Guest adegnes Posted June 14, 2007 Report Share Posted June 14, 2007 Before I started the rebuild of my car, I was running ca. 14-15 psi. With The big FMIC, 3bar FPR, bigger injectors (and maybe some kind of water injection) hopefully I'll be able to raise it to 20-21 psi Don't know if the stock turbo can handle it though... If I was to use it as a daily driver, I would have backed the boost of a fair bit.... Quote Link to comment Share on other sites More sharing options...
Bean Posted June 14, 2007 Report Share Posted June 14, 2007 If you're planning to run at that PSI the stock turbo is going to be out of it's range of efficency and it'll likely generate a wack of heat. The FMIC will help of course - but you'd be much better off using a turbo sized so that's nicely in it's efficency curve. Car will also flow more air volume which is just as important as boost values, so a better turbo will make more power at the same boost by flowing more air, and producing it with less heat. Rabin Quote Link to comment Share on other sites More sharing options...
Guest adegnes Posted June 15, 2007 Report Share Posted June 15, 2007 True... I can get a T3/T4 hybrid (T34? the one with T3 exhaust, T4 compressor) cheap, you think that'll do? Maybe I'll manufacture a top mount manifold while I'm at it... (will be fun with my allmost non-existent welding experience...) Quote Link to comment Share on other sites More sharing options...
Bean Posted June 15, 2007 Report Share Posted June 15, 2007 A T3-T4 hybrid would be pretty much perfect... If you can get the specs of the trim levels of the compressors used there should be some tables available that will tell you exactly what range of efficency it has - and it'll show you how good of a fit it will be for the engine. If I can afford it I want to use the new Garret GT series of turbos... (Maybe a GT28 or 30 - depending on the requirements since I want boost ASAP!) Rabin Quote Link to comment Share on other sites More sharing options...
V-M Posted June 15, 2007 Report Share Posted June 15, 2007 Before I started the rebuild of my car, I was running ca. 14-15 psi. With The big FMIC, 3bar FPR, bigger injectors (and maybe some kind of water injection) hopefully I'll be able to raise it to 20-21 psi Don't know if the stock turbo can handle it though... If I was to use it as a daily driver, I would have backed the boost of a fair bit.... I would not go over 1.1-1.2 bar with original turbo and min. 2,5" (3" recomend) down pipe. Back pressure is generating just heat and not gaining any power. Water injection is nice but it has very minimal effect on power dependin if it's on spray to cylinder or spray to FMIC?. Some Subaru WRX test was at it was more effective on FMIC but amount of water needed is back gained by weight of water V-M Quote Link to comment Share on other sites More sharing options...
Trevor Posted July 11, 2007 Report Share Posted July 11, 2007 dont forget about the volvo bypass valves. I'm a big fan of those things. they're easy to come by around here and fit will in your pocket. They are all metal construction (aside from necessary diaphragms and seals) and seem to work beautifully. PSHHHHH Quote Link to comment Share on other sites More sharing options...
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