Hello everyone, I have a problem with the g23 project. I put: F23a7 block Nippon racing k20 pistons Max pending forget rods All bearings acl race Head h22a5 ported and polished H22a7 cams Skunk2 pro intake manifold 410 denso injectors Everything was arranged at the mechanic's, and after working out the engine with the safe map, I went to the rollers to map the car properly. My tuner sent me a graph showing that after 7200 the engine power drops drastically, but it should drop slightly and the engine changes its sound after 7200/rpm, after four pulls on the dyno the engine started knocking, it says that the connecting rod has blown. The mechanic is surprised and says that he did everything 100 percent and checked and he doesn't know why the power dropped so drastically.. The oil pressure is there because otherwise the vtec wouldn't start.. Does anyone here have any idea why this happened?? I am sending a graph

 

If it's knocking then the engine was assembled incorrectly. Period. Either wrong bearing tolerances, torqued incorrectly, or otherwise. If the balance shafts were deleted incorrectly then it's possible you had insufficient oil pressure for high RPM operation, but not necessarily low enough to have VTEC issues or problems in the lower rev range. You should ALWAYS be monitoring oil pressure on a new engine build like this.

If the pistons weren't flipped to be run "backwards" or you bought pistons with insufficient valve reliefs then it's also possible you damaged valves. I have seen this before on setups with similar parts combinations.

If none of that were a problem, I would say that with the F23 crank power will fall off in the higher rev range due to the long stroke. I'm making power to 7800 with one on my turbo car with stock JDM H22 cams so your power shouldn't be falling off that hard regardless. It's likely due to whatever caused the engine failure.

 

The balancers were not wiped on the engine, I used Eneos 5w40 oil. My mechanic fits f23/h22 for the first time, so it's possible that he made a mistake, but it's hard to admit. Is it possible that the oil pump is stuck? I didn't put an oil pressure gauge, but now I definitely will. One thing is definitely not clear to my tuner or to me. How is it that it tells him on the rollers that the vtec is open and the power drops so drastically as if there is no oil pressure and vtec?? What should you pay attention to the most? I don't need a new connecting rod or 4 new ones because you can't buy one and the other crankshaft😰 so I would like this not to happen again, thanks for the answer😃

 

The balance shafts should have been deleted because, once you have altered the internals of the engine, they do nothing. They only exist to eliminate NVH for a "smoother" feeling engine in the first place. They do nothing for engine harmonics. Deleting them also increases oil pressure and lowers oil temperatures by a fairly decent amount.

The oil pump cannot get stuck. It's driven directly by the crankshaft. The internal gears can shatter under some circumstances which would result in no oil pressure at all.

 

I know that it is better to delete the balancers to have better pressure, I read about it but I don't have more budget because I have to pay for expensive repairs and then mapping at the tuner, so I would leave it as it is. So vtec can work even with lower pressure, but that's why the power drops quickly, right? Thank you for your reply

 

I do not know the exact figure but in a completely OEM application, I assume VTEC would require 50-60psi of oil pressure before activating. HOWEVER, in an aftermarket application, it is possible to completely remove the oil pressure requirement for VTEC to activate. This is common practice when tuning cars, especially when they have a JDM VTEC solenoid that does not have an oil pressure sensor. So if your tuner disabled this check in the software, VTEC would attempt to function without sufficient oil pressure.