so i got a couple of nasty warnings from Skunk2 guys about degreeing in my cams. they said +4/+4 is the quick setup, which is pretty much irrelevent since since the head has been milled 0.020". im looking for someone with history or a degree wheel setup who wants to help me get this these cams in and sorted out. “help” will be reimbursed for their lost time. if that person also has a dyno and can tune an obd1 motor, that would be even better
JDM GSR milled 0.020, Mugen head gasket = 11.4:1 static
Skunk2 Tuner2 cams, Tuner gears, tuner springs/retainers
Skunk2 IM V2 port matched to Skunk2 68mm TB, short ram intake
4-1 header, 2.5" collector, 2.5-2.25 test pipe, Tanabe SMH cat back
Well, for starters it would be a great idea to find the center lines of the new cams. Skunk2 shuld be able to provide you with that. Next, compare the center lines to the OEM specs for your previous cams. That should give you a starting point. Add the intake advance due to milling/shaving to the centerline difference and you have a place to start tuning.
…or are you specifically looking to have someone do this?
well since a degree wheel kit runs about $300, and i dont plan on doing this again, i’m looking to have someone do it for me.
i bought a whole skunk2 b16 head, hence all the s2 parts. not my first choice in aftermarket stuff, but the price was right. i was supposed to use the s2 flat valves that are in it instead of milling the head, but 5-6 were damaged(over rev) and Skunk2 wouldnt sell me replacements. the pistons are stock 10.6:1 JDM GSR. my compression test came back 180-181-180-179 so i didnt feel the need to tear the block apart and buy ITR slugs.
Again, those results are from a stock JDM GSR. I dropped it off at the mechanic and asked for a compression test, didnt bother with a leakdown because head was getting redone anyway
dude, wtf are you guys smoking? a 10:1 cranking compression motor makes 185 average. 240 would be like a 13-14:1 race motor.
this is a b16 head on what block? Either way, B16 head chamber is bigger than a gsr head, so on gsr slugs (less dome than B16 slugs) should numerically create lower compression, so considering the setup, thats actually really good compression number.
I would just slap it together and set the cams at -2/2 and fire it, set base timing and see how it sounds. There’s going to be very little variation between degreeing the cams and the base setup.
The B16 pent-roof chamber is indeed larger than the GSR, so it will be dependant on the block/head combo.
Regardless…the centerlines of the OEM cams and the Skunk2 are VERY close. If the head is off the block right now, put the cams in and see what the +/- limits are on the cam gears using a section of an old T-belt. That way when you DO tune the thing, you’ll know what advance/retard will make the valve touch.
My stock block/head b18a read between 180-185 for each cylinder and the book says standard is 184 psi and min is 135 psi for the 9.whatever:1 compression the pr4 b18a/b Ls motor is. Gsr with a b16 head should definetly be in the lower 200’s psi.
okay i must have had my numbers mixed up. i thought the GSR was 200 Nominal, so i figured 180 was good for a used engine, and since they were so close together, it seemed right to me.
heres a seperate scenario:
Milled 0.020" GSR head
JDM ITR +0.25 pistons
0.040" turbo head gasket
since the gasket would compensate for 0.014" of the mill, would i still have the same problems?
I don’t think you’ll have issues at all. The domes on my pistons are over 8cc’s and I have zero issues. The Skunk cams aren’t all that aggressive, but you’d be one step ahead if you can find what degree setting are your limits for v to v contact. You won’t have to worry about hitting the tops of the pistons unless your timing is WAY off.