The first thing Tom did was to remove the damaged valve seat and replace it with a performance nickel bronze part. Nickle bronze conducts heat exceptionally well, is tough and wears well and is easy to cut. Tom then checked our valve guide clearance and found our guides to be in excellent condition and not in need of any work which is typical for a Japanese performance engine.
|The Nissan SR20VE is a stout and reliable engine. However we suspect it didn’t appreciate us tinkering with it a little too aggressively. The other bummer is that being a JDM engine, you just can’t get parts from your local Nissan dealer if it messes up. Some parts are interchangeable with the SR20DE but just about everything in the head isn’t.|
We could not find any new SR20VE valves in the country and had to turn to the aftermarket. The SR20VE has a shorter valve stem length than the SR20DE so we had to run a valve done just for this engine. Tom sourced some inconel Supertech SR20VE valves. These valves were 2mm larger than the stock valve, a spec that we didn’t really want. A stock bore SR20’s valves are shrouded by the combustion chamber and the oversize is more appropriate for a big bore engine. 2mm oversize is the largest valve you can get into the stock seat.
|Maybe we had problems because our Nissan N1 cams have a lot more lift than the stock cams.|
Since we didn’t want to make a bunch more power and didn’t want to overbore our engine, Tom turned down our valve heads 1mm. This would reduce shrouding and give plenty of valve area for our standard bore. It would also allow Tom to open up our exhaust valve seats a bit for better flow and to seat the valves nice and high for good flow as well.
|We also had our lobe centers turned pretty tight with our JWT adjustable cam gears. We only had about 0.040″ clearance between the exhaust valve and piston. We learned that this is probably not enough the hard way. We will be fixing this as our engine comes back together. Note to self you probably need about 0.055″ clearance on this engine in the future. We will actually shoot for around 0.080″ with custom pistons when we fix the rest of the engine.|