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Hey guys, i have a problem with an engine i built.
Heres the deal. The engine comes from a car that hasnt rolled all last year. Before the car was put away, it was rolling fine. The car though sat outside for a whole month without a hood, so mother nature had the chance to do its magic to it. It had no mafs (turbo cold side opened), no cold side intercooler piping, meaning that the intake manifold had an opening. So with that said i decide to open the bottom end to put a crank collar, new bearings and jun oil pump. While building the engine, ( its my 5th i do for myself and entourage), i measured with plastigauge the clearence of all bearings, as usual, make sure its in specs of nissan shop manual everything is, torqued all bolts from crank bearings to nissan specs with a brand new snap on torque wrench, all rod nuts to nissan specs, i didnt cut any corners round. Put the engine back in the car, install new known working mafs, intercooler piping, and start the car. Marvelous, everything works fine. Adjust timing, tps, flush the first startup oil, adjust water level and decide to go gaz it up with a buddy of mine as a first drive. As we are going, coming to stops the engine's idle goes up and down, meh, will check it out later with new mafs or iac. All we notice on our way to gaz up. During the 5-10 minute drive no knocking was heard. I tell me friend who owed me money gas it up for me. Without me paying too mucb attention, at 25$ i realise that he is putting 87 octane. ****. I tell him fill the other 25$ with 91, and well see what happens. On the way back we started to hear knocking. Flush the old gas, make the tank empty and put 91 in it, still hear knocking. The funny part is, knocking wont occure at idle, neither under boost, neither if you rev it up slowly to 2500 neither if you rev it up super fast. The knocking only happens from 3000-3200 or 3500, with a very mild load without boost on the engine., if you go full throttle no knock, mid throttle with light boost (1 to 2 psi) no knock, if you gas and let go of throttle in the knocking range you will hear it. Let go of the throttle 6k rpm and let it go down, no knocking sound can be heared. When im under the hood and look to see where its coming from, seems to be coming from piston 4-5. Usually engines that knock can be heared at idle, slight gas, high rpm... Anyone got any idea what it could be? The top of engine ( cams headgasket intake exaust manifolds havnt been touched) can a rod knock only happen at a specific rpm?
Thanks for your opinions guys, i just dont feel like pulling back the block appart and be like , " yep" nothing was wrong.
Heres the deal. The engine comes from a car that hasnt rolled all last year. Before the car was put away, it was rolling fine. The car though sat outside for a whole month without a hood, so mother nature had the chance to do its magic to it. It had no mafs (turbo cold side opened), no cold side intercooler piping, meaning that the intake manifold had an opening. So with that said i decide to open the bottom end to put a crank collar, new bearings and jun oil pump. While building the engine, ( its my 5th i do for myself and entourage), i measured with plastigauge the clearence of all bearings, as usual, make sure its in specs of nissan shop manual everything is, torqued all bolts from crank bearings to nissan specs with a brand new snap on torque wrench, all rod nuts to nissan specs, i didnt cut any corners round. Put the engine back in the car, install new known working mafs, intercooler piping, and start the car. Marvelous, everything works fine. Adjust timing, tps, flush the first startup oil, adjust water level and decide to go gaz it up with a buddy of mine as a first drive. As we are going, coming to stops the engine's idle goes up and down, meh, will check it out later with new mafs or iac. All we notice on our way to gaz up. During the 5-10 minute drive no knocking was heard. I tell me friend who owed me money gas it up for me. Without me paying too mucb attention, at 25$ i realise that he is putting 87 octane. ****. I tell him fill the other 25$ with 91, and well see what happens. On the way back we started to hear knocking. Flush the old gas, make the tank empty and put 91 in it, still hear knocking. The funny part is, knocking wont occure at idle, neither under boost, neither if you rev it up slowly to 2500 neither if you rev it up super fast. The knocking only happens from 3000-3200 or 3500, with a very mild load without boost on the engine., if you go full throttle no knock, mid throttle with light boost (1 to 2 psi) no knock, if you gas and let go of throttle in the knocking range you will hear it. Let go of the throttle 6k rpm and let it go down, no knocking sound can be heared. When im under the hood and look to see where its coming from, seems to be coming from piston 4-5. Usually engines that knock can be heared at idle, slight gas, high rpm... Anyone got any idea what it could be? The top of engine ( cams headgasket intake exaust manifolds havnt been touched) can a rod knock only happen at a specific rpm?
Thanks for your opinions guys, i just dont feel like pulling back the block appart and be like , " yep" nothing was wrong.
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