David K Posted October 16, 2003 Share Posted October 16, 2003 The pump will be my next project i suppose Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 16, 2003 Share Posted October 16, 2003 One idea: You can take the plug out of the oil pump, drill a hole in it, tap it for a large bolt, then cut the head off the bolt and cut a slot in it for a screwdriver and put it back together, now you have adjustable pressure. I think someone sells something like this, maybe MSA? A buddy made mine, and gave it to me when he no longer needed it. It works, but it drips just a little bit. I'm not a clean freak though. I'd rather have the oil pressure where I want it and have a little drip... Jon Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 16, 2003 Share Posted October 16, 2003 Hmm...I don't know why you couldn't just put some kind of sealant (or even epoxy) over it when you have your pressure set. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 16, 2003 Share Posted October 16, 2003 Good point. I won't be adjusting that thing for a LONG WHILE Jon Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted October 16, 2003 Share Posted October 16, 2003 I've thought about making one of those but, just never got around to it. I think it would be best used on the high volume pump and not the regular pump. That way you would have plenty of volume with the added pressure. Quote Link to comment Share on other sites More sharing options...
Afshin Posted October 16, 2003 Share Posted October 16, 2003 benefit of hydraulic lifters: -quiet (by decreasing slack in valvetrain) -no loss of lift or duration from heat expansion -built in shock absorber reduces wear and tear on valvetrain -long service interval, so more likely that valve lift and duration are not off Benefit of solid lifter: -cheaper -tolerant of dirty oil (relatively) -better function at higher RPM (over 6500-7000 rpm). Properly matched springs and HLA can still run over 7000RPM, it's just that the solid lifter will perform better at that point. Regarding the bleeding of lift or duration it has been argued that it may decrease the area under the curve for the power band (by causing less lift/duration as mentioned by Jon). However some have claimed the bleeding at low rpm (causing shorter duration or lift) would increase low rpm torque and widen power band), and crane actually makes high performance HLA designed to bleed at low RPM but not at high RPM(sort of a variable valve timimg) . All in all, most experts seem to agree (never all) that for under 7000RPM any performance difference is minimal (and certainly not 20 or 10 HP). Considering this along with less wear and tear, quiet and more likely not to be out of adjustement, almost all modern day engines have HLA despite the higher cost (including MB, Porsche, corvett, audi, some motorcycles and Lycoming aircraft engines....). The oil pump is not a measurable factor for HP loss in solid vs. HLA lifter (same oil pump in solid lifter and HLA ZXT's) Off course I still want a high pressure and volume oil pump for the track Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 16, 2003 Share Posted October 16, 2003 I don't think they were saying that the oil pump would affect hp, I think they were talking about lifter noise. Quote Link to comment Share on other sites More sharing options...
Afshin Posted October 16, 2003 Share Posted October 16, 2003 the guy said that the loss of HP was on a built engine and it was due to the added volume that the oil pump must provide for the HLA's Hi Bill, I was refering to this statement made earlier, which Cody also said did not make sense. I was confirming his opinion. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted October 16, 2003 Share Posted October 16, 2003 Okay... now about rockers... I was always under the impression that the p90 and p90a used different rocker arms. Is that the case or are they compatible? I seem to have bad luck with worn rocker arms.... Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 16, 2003 Share Posted October 16, 2003 Ahh...I must have skipped that statement. No, the reason for the potential ultimate hp loss does not have to do with oil pressure, it's basically an issue of the HLA being able to "keep up" with extreme cam profiles at very high rpm's. The problem is this...until you're tuning 8000rpm pushing about 800hp out of your L28...it's not a problem. Quote Link to comment Share on other sites More sharing options...
240ZinTN Posted October 16, 2003 Share Posted October 16, 2003 I finally remembered my password! I recently found a turbo motor with a P90A head. everything looked good until I took off the valve cover. Apparently someone had gotten to it before I did and snagged one of the Hydaulic lifters. Does anyone have a good source for replacements? Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted October 16, 2003 Share Posted October 16, 2003 Rhodes and Crane make hydraulic lifters for taming bigger cams. They basically "bleed down" at slower speeds where oil pressure is not as high. I suspect that a larger oil hole is part of the equation, but I believe the Crane design also had some sort of a flapper valve for oil control purposes. The Crane seemed to be a quieter design IIRC. Another advantage of the larger oil hole would be the "anti pump-up" feature at higher rpms (which would tend to limit the valves opening/closing action and thereby limit rpms). Having said all of this, if you are using the stock cam and getting all the way to redline, I wouldn't open up the oil hole... JMHO based on the very little I have gleaned over the years. Brad Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 16, 2003 Share Posted October 16, 2003 Brad makes good sense here. I was thinking that the lifters would bleed at high rpms, but it makes a lot of sense that they would bleed at low rpms when oil pressure is down, and may hold the valves open at high rpms if the pressure in the lifter is too high. Thanks Brad! Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted October 16, 2003 Share Posted October 16, 2003 what about the rockers arms? are they the same between the hydraulic and non hydraulic heads or what? Quote Link to comment Share on other sites More sharing options...
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