Sr20VET drift engine tuning advice

Dear Community!

We just finished tuning and dynoed a Nissan sr20vet engine which will be used in competiton drifting. Here is a short spec list: P11 head, 1mm/2mm bigger intake/exhaust valves Kelford 180ST camshafts, supertech valve springs and retainers, mild port work. Bullet engineering billet block, 91mm crankshaft, carillo rods, cp pistons 89mm, 10.5:1 compression, dry sump system. 8370 borg warner efr twin scroll turbo. Haltech nexus r5 ecu. Fuel E85

One of the dynosheets is with a 75hp nos shot, the other without. The tune is quite conservative, we left 20 to 30 hp on the table to have a greater safety margin. There is a bump in the hp and nm graph and the engine is also getting a bit richer there. No knock, everything else is as it should be. May the members and tutors give some advice what can cause this bump, for me it looks that the cylinder filling is decreased in this rpm band. With the nos shot the bump disappeared.

Thank you and happy eastern!

I can't find those cams on Kelford website, are you still running the VVL? If yes, does the bump happens at a VVL switching point?

Hi!

Thanks for the reply! I made a mistype, the cams are the 184-ST. The VVL switch point is at 5800.

Hi Christian,

comparing the two graphs, I think that the dip in the NOS graph has not fully disappeared, it is still slightly visible. Could you maybe change (lower) the smoothing setting for the graphs? This might help to see what is going on.

I do not think it is the vvl switching point as it is so far away, but just to rule things out, you could maybe try to move the switching point around to see if it has any influence on the dip at all?

On a side note, did you log the turbo speed on the runs? I am asking as even with this highly efficient engine and E85, you might be in the red zone above 800 PS.

I've seen some partially blocked oil passage or sticky VVL solenoids that were retarding the actual switching point. Right now I don't see nothing happening at 5800rpm on both graph, so either your switching point is realllyyyy at the right moment so the airflow is linear (which I doubt) or the switching point is happening too late. I would still try to change the switching point for a lower RPM (like 5000RPM) to see if the dyno curves change.

Regarding the turbo speed, yes we log it and at 2.5 bars which is the maximum boost we are running it is around 119.000 rpms ehich is around 10.000 before the maximum allowed allowed shaft speed of 128.000 rpm. So we are on the edge but not overspeeding it.

We also checked the vvl activation with a generic output when the car idles and it works, so a sticking vvl can be ruled out.