Since the re-build I have this valve train noise at idle and just above ... anyway thought it was collapsed lifter so finally got around to checking it out. What I found was that both inlet cams were missing their vtc check valves hence making a bad lifter really bad and obviously NO vtc working. All back together and the difference was very noticeable ... put the car back on the dyno to check the tune and measure the difference the vtc has made. Below are comparison graphs: 4/11/08 = pre rebuild with no porting, no manifold and turbo exhaust housing mods ... does include cams and no vct. 2/12/10 = 200km on new engine with no vct ... does include porting, fancy valve seats, modified exhaust manifolds and turbo housings VCT = after a couple of runs to check the tune was safe (no tuning done) ... includes vct. There is easily more there if time is spent playing with a/f ratio (quite rich at top end), timing, vct release point and cam timing and more boost ... injectors are at 85% using factory fpr. The dyno didn't show a massive difference in the way the boost comes on ... on the road is VERY different (eg. 10psi is showing at 4000rpm)????? must have something to do with different loadings ?? In summery: Still looks a bit "lazy" under 4000rpm ... a function a running Turbos with larger Exhaust Housings ... definitely feels more lively on the road Power is up from 415rwkw to 434rwkw (mainly by increasing boost from 14 to 16psi) but is making 415rwkw 625rpm earlier Torque is up from 615nm to 647nm but is making 615nm 1100rpm earlier Boost is coming in earlier with 14psi being made about 1100rpm earlier The greatest improvements actually came from the work I did to improve how the engine flowed and getting the VTC working is icing on the cake .... Is VTC worth it? hell yes!!!
Turbos = tb2804 (Pulsar GTiR) .86 exhaust housings with the wastegate hole filled and ground/polished smooth. CAMS = 274.11 Duration ... 9.31mm Lift ground by local CAM Shop.
Gee m8. Thats pretty impressive. Using those turbos along with a 270 odd degree cam, Id guess your going to be hard pressed to get it to grunt up much around 4 and fill that dip. I tend to think that hole is highlighted more by pretty good low down rather than much wrong in the "hole" Once that thing lights up, it has a long and hard pull right to 7 grand and Id say well beyond before youd bother changing gears. Id suspect apart from messing with ignition would be to go smaller turbine housings in an efforet to boost it up lower down but at the expense a bit of tha particularly impressively long top end. Its a fair cam you have in there! Cheers E
Got to love the VCT great numbers ! but yeah like tas said .86 and the big 274 kills down low with .64 you will definitely spool better and still have a good topend with 274 cams
Is that enough to convince you to put S2 gears back on Chrispy? You know you want to fiddle around with your cam timing some more
The only drama with our VCT is its a fixed amount and stepped. On or off. If it were continuously variable CT then THAT would be worth the effort to mess with and yield good results! L8r E
.64's would have definitely helped the bottom end, but I had decided I wanted .86's and by god I was going to make them work The car actually is quite nice to drive with it's current mode of power delivery in that you can actually use some throttle without inducing instant wheel spin. Accelleration is steady (not slow ) then the thing just goes nuts, but by then the momentum reduces the "need" to break traction ... although at full power in 3rd it is still trying to break loose ... it is an "odd" feeling accelerating hard past 160k/h with the rear tyres slipping then catching repeatedly.:br:
I am sure more improvement could be made by playing with the cam timing, I am reasonably happy with what I have (for the moment , at least ) so I can't justify the extra expense in both hardware and dyno time. My inlet gears are adjustable but have set them to zero.
We'll see I put the check valves in the cams and reinstalled the solenoids. All I need to do is put on the VTC gears. I did notice that the solenoids did contact the check valves when installed. Is that normal? S2 cams with S1 check valves. Their is no circlip groove for the check valve in the S2 cams either. I loctited the valves in. Might have to get my old cams off you...
Have updated the dyno graphs (a couple mistakes with transfering #'s) ... there is no "edit" available so had to repost the new ones.
Do you want to take it down there next time for the tune? Maybe it just doesn't like me any more like a dog hates the vet after surgery :rofl: I could follow out of sight with a trailer for the inevitable drama she always throws out there. So far ~350kws at the wheels on 11PSI @ 6800RPM still climbing sharply and not even fine tuned [TIS] BUT that counts for nothing if it wont run properly - should be OK now except maybe for VTC noise if it starts. The real challenge will be to beat you with my own car without spending up large on cams .... now THAT wont be easy.
Went to the SDU dyno day yesterday ... the car had an issue eg: leaning out and detonating from about 4500rpm on the high boost setting (16psi) ... any way tried it on low boost (13psi), still detonating a little bit but we felt ok to make the run which = 374wkw (ecu was most likely pulling timing as well) ... so, not that bad really but concerned but the lean issue, obviously!! On the way home was trying to think what could have changed since the tune ... only thing I could come up with is when I had it tuned the VTC gears were really rattly and may not have been working correctly and not advancing fully so when I replaced them with some non-VTC adjustable gears set to what the VTC cam timing should be ie 10' adv. (actually set them to 9') the extra cam adv. throw the AFR's out ?????? What makes me think this is, although the boost level was only 13psi the car made 100nm more @ 4500rpm than it did @ 16psi when it made 434wkw. Disapointed but optimistic :br: Dyno Run:
It's a shame I had to work yesterday, I'm sure we could have squeezed that 11Kw at the wheels to beat you Time we built that test rig for the engines I think, get all these little pain in the ass issues out of the way BEFORE bolting the engines in the car. Looking at the graphs your car is just a little behind (30-40KW) mine most of the way but then peaks just a little higher. Not a bad effort given yours was on ~13PSI and mine on 23 tapering down to 19 (was set for 17PSI but boost controller not operating well). Time for some very subtle cams in mine just to help out a little without killing off boost power :br:
