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BH Primary upgrade - sorta kinda how-to


Marky
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Figured I\'d do a real quick write up on how (& as it turns out why) you\'d do a VF27 / BB core upgrade to your BE/BHShort version is that first off all the turbos - VF25, 26 and 27 - all share the same "wheels". I have no idea about any of the earlier models. The differences are that the 25 and 26 primaries have journal bearing cores, the 25 is the auto-model with a smaller exhaust housing than the 26, and the 27 is a BB core and in the secondary position with no wastegateSo I *thought* my primary was on its way out, and figured I\'d give it a whirl putting the 27 in instead being 1/4 the price of a 25/26 and also being that I was curiousFirst step is removing the original turbo - this job sucks. Need to remove the intercooler - unbolt the water pipe and oil feed - disconnect the wastegate arm - then go get beer cause you\'ll need itThe super bastard a-hole bit is trying to get the turbo core out, without having to try and crack the exhaust housing off. If you want to go that way then sure - I didn\'t bother. Regretted it a bit. The way I did it was to unbolt the oil return off the core, undo the circlip holding the turbo together - and then lever the mofo out. Bastard bit was getting the oil return unbolted, not much room to work with. Step two is deciding how you\'re getting the new core in there. Three options - 1: Make a "spacer plate" donut of approx 1mm to space the VF25/6 housing out enough to fit the slightly deeper BB core, and sandwich it in - bit iffy as you need to disassemble the turbo to do it and it\'s pretty redneck (even for me)2: Do it the proper way and get your VF26/5 housing milled out that tiny bit to fit 3: The Marky method of "rounding half the allen bolts holding the housing together, giving up and making it work facing the wrong way instead"Options 1 and 2 are self explanatory - option 3 was simple for me as it worked in nicely with the FMIC piping I had anyway. One point to note was the WG actuator then needs to be drilled to suit the wrongly-placed lugs on the turbo (oh and you need to drill that out too). The other thing is that you are left without a wastegate feed point - I just feed mine off the manifold anyway but it may be something you need to allow for. Fitting it back in is ^^ in reverse, at this point I noticed that apart from being ripped beyond hope (they do it with age anyway) the inlet to the primary is ridiculously tight - so I just replaced it with a 2" silicon bend cut to size. Mucho more openo. Rest of the inlet seems not as bad and is in the too hard basket anyway. DSC_0216_zps9b8ea01e.jpgDSC_0191_zps4498839d.jpgNow the fun bit - why did I do it- I *thought* my primary was on it\'s way out, was starting to get a bit of a whistle on boost. In hindsight chances are it was an air leak from the inlet pipe as it seems just fine. - Using 10psi as a "marker" - the best I\'d normally see that level at would be around 24-2500 in 4th, just bumbling around. Driving it now is honestly almost like a diesel - it makes 10psi literally by about 1700 rpm, the gauge just pivots in time with my foot regardless of RPM. (On a side note this did my already crook clutch no good) VOD is drastically reduced too, it just feels like a momentary stumble rather than the big dip it normally is. (I don\'t know how much the FMIC has helped with this mind you)As for argument as to why bother - for $50 and an afternoon of my time it was well worth it. The response is genuinely that fast - it wakes up faster than anything I\'ve driven but without the drop off in top end you\'d normally get and makes it really nice on the roadWhy they didn\'t just make it like this in the first place is beyond me

Edited by Marky
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