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| turbotrana |
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I dropped off my forged BA pistons to my engine machinist to have the valve relief milled out to match a stock E series piston.
He suggested that I first check with the dummy assembly as to whether it actually needs the notches milled as he reckons he has come across a few engines that have notches milled but when they checked found that they could get away with no notch. The valve notch when done is the weak area of the piston. Has anyone ever checked this. It would entail most of the engine assembled then rotating it with some plasticine in the critical area to see what clearance you get on a full rotation of the engine.
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| ebs_4l |
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i know people have checked this with big cams, and yes, PTV clearance was an issue
_________________ EB 4L, 8.4:1, R154, GT4202r, 4in exhaust, Greenslade Engineering exhaust manifold, plenum chamber, 90mm throttle, Garrett W2A cooler, Surecam custom, autronic SM4, Bosch 120lb, Crane HI-6, LX-92, LM-1, Turbosmart Reg, 2x bosch 044, turbosmart 48 gate. 470kw+ @ 18PSI |
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| EBXR8380 |
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The weak link is when there's little material between piston top and first ring...
Usually caused by detonation....
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| aaron_hogan |
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Side by side the BA piston to the E-series. The BA inlet valves notches are not directly in the same place but it is close. (you probably knew that already).
Surely the crowns aren't that thin that it becomes an issue to remove such a minor bit of material. Consider how much is lost in a Clevo valve relief toward the top ring land? Also bear in mind the difference in depth of the EF-L notch compared to the more shallow AU notch. Most books will tell you if it clears when dummy assembled less head gasket then you won't have a worry. The problem with that is your cam timing then becomes a factor. Presumably you may want to retard the cam a tad? In that case its maybe even less of an issue. I don't think cam lift has any bearing on it. I am no engine builder so I would err on the side of caution and do a dummy build with an old gasket and bolts and a bit of plastiguage. If you can remove and re-fit pistons at home then it lessens the headaches of doing this. Plus you would only have to dummy one piston/rod assembly with no rings. There are people here with much more experience than me on this stuff.
_________________ EA SVO Fairmont Ghia - Recaros, Bilsteins, Sunroof, SVO rims and body kit, Genie headers, DBA rotors. T5 steeda triax short shifter. 3.27 lsd. (EL 4.0 ported/polished, rebuilt and balanced, Dev5 cam. J3 chipped EL ecu, AU injectors). |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
turbotrana wrote: I dropped off my forged BA pistons to my engine machinist to have the valve relief milled out to match a stock E series piston.
He suggested that I first check with the dummy assembly as to whether it actually needs the notches milled as he reckons he has come across a few engines that have notches milled but when they checked found that they could get away with no notch. The valve notch when done is the weak area of the piston. Has anyone ever checked this. It would entail most of the engine assembled then rotating it with some plasticine in the critical area to see what clearance you get on a full rotation of the engine. you could always notch them yourself. the tool for doing it doesn't cost alot. but yes as with anything on a build like this one, dummy assemble and check every thing. More then once. So long as you dont make the piston crown to thin, you can never have enough piston to valve clearence, cutting it there even if you could get away with out might just save your engine if something lets go one day |
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| turbotrana |
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now knowing that the AU has a shallower depth than the E series then I think I will get him to mill it to the AU depth. But I need a AU piston for him to measure from. ANYONE with a used AU piston that they can send me. I will pay for postage.
EBXR8 -yes with the E series when notched leaves minimal material on the upper lip so this is why my machinist had concerns in this department. EBS-4L I think you definately need the notch but I am glad I asked because it looks like that you can reduce it to the AU size so that it does not impact on that upper lip as much
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| turbotrana |
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Aaron-Hogan : to my surprise the BA piston has exhaust valve notches but no notches for the inlet valve. I had them side by side and tripple checked. At least I hope I am right otherwise my forged pistons will be cut wrong.
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| macxr8 |
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Age: 55 Posts: 451 Joined: 3rd Jan 2005 Ride: AU XR6 with BF Turbo engine Location: Sydney |
If you are using E Series rods, you will also have to machine the pin boss on the forged pistons out. E series is 23.17mm BA is 22.00mm
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| turbotrana |
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using BA ARGO RODS
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| aaron_hogan |
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oops i was looking at the piston back to front
_________________ EA SVO Fairmont Ghia - Recaros, Bilsteins, Sunroof, SVO rims and body kit, Genie headers, DBA rotors. T5 steeda triax short shifter. 3.27 lsd. (EL 4.0 ported/polished, rebuilt and balanced, Dev5 cam. J3 chipped EL ecu, AU injectors). |
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| HiBoost |
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turbotrana wrote: I dropped off my forged BA pistons to my engine machinist to have the valve relief milled out to match a stock E series piston.
He suggested that I first check with the dummy assembly as to whether it actually needs the notches milled as he reckons he has come across a few engines that have notches milled but when they checked found that they could get away with no notch. The valve notch when done is the weak area of the piston. Has anyone ever checked this. It would entail most of the engine assembled then rotating it with some plasticine in the critical area to see what clearance you get on a full rotation of the engine. in few weeks time im buying a set of H-beam rods and forged ACL piston to suite the xr6 turbo engine which will make its way into my 4lt el donk for high boost levels, it will cost me $2000 for piton and rods
_________________ 4LTR-JET: 9.1 @150mph!! |
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
macxr8 wrote: If you are using E Series rods, you will also have to machine the pin boss on the forged pistons out. E series is 23.17mm BA is 22.00mm
you can't use E series rods with BA pistons. the compression hight is different. Last edited by tickford_6 on Mon Dec 29, 2008 7:25 pm, edited 1 time in total. |
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| auturbz |
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I'm not very mechanically minded but if i were to rebuild my au motor using xr6 turbo pistons and rods to bring down compression (au is turboed)would it fit hassle free in the au block?
Thanks in advance |
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| turbotrana |
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It would fit no problem, just make sure you use the stronger LPG rod as the stock BA turbo rod is pretty weak
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| ebs_4l |
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so wheres the outcome from this thread??
_________________ EB 4L, 8.4:1, R154, GT4202r, 4in exhaust, Greenslade Engineering exhaust manifold, plenum chamber, 90mm throttle, Garrett W2A cooler, Surecam custom, autronic SM4, Bosch 120lb, Crane HI-6, LX-92, LM-1, Turbosmart Reg, 2x bosch 044, turbosmart 48 gate. 470kw+ @ 18PSI |
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