Just an update...

The engine in question in this thread with the Revolver cams, we took the car out tonite for it's first shakedown. As you recall we found the LC on the intake cam was at 87 ATDC. That meant we were 22 degrees from Revolvers suggested 109. We made up this difference with 11 cam degrees retard with Fidanza pulleys.

From the first start up a couple days ago, the idle was very smooth and the engine seemed to run very nice. Tonite we ran off spring pressure as high as 18 pounds. The car felt really nice for a conservative tune we thought. Car will be mapped in a month buy a professional so will keep you posted.

Spec of friends Evo 6 is 2 litre Evo 8 motor, autronic sm4, aries pistons, eagle rods, revolver cams, evo green, ported intake mani, exhaust mani, and throttle body. Oh and a Greddy IC.

Also my other friends Evo 6 with Buschur head and shortblock is in and running well too... spec is also HKS 272's, autronic smd, evo 9 turbo.

And!.. my Magnus 2.4 crate motor finally shipped! Should have it next week! Spec also is Autronic SM4, MAD spec Piper cams, AMS GT35R, Magnus intake mani, 63mm ported TB, and an APS intercooler. I'm praying I don't do anything wrong getting this motor going. We live in the Caribbean, so tuner flies down to do the mapping. However, we are forced to get the cars up and running off base maps and some tweeking to make sure the cars are ok prior to the tuner coming. It's scary!

Anyway, hopefully the Revolvers are happy how we have them set on my friends car. Will keep you posted once the mapper comes and we run some real boost.

Ohhh! Our drum of VP Import arrived this week too! Getting exciting!

 

so there are grossly out of spec revolvers out there?

 

learned so much with this thread

 

Well this is what we found... but we are not experts thats for sure

However I can tell you, my friends engine is idling and running very smoothly with his intake cam retarded a whopping 22 degrees crank. I guess we'll know more when Mark from England comes to tune and we see how the engine performs at various settings at full boost.

 

This car was tuned and is running well with the cams degreed as described in this thread. On very crappy pump gas (can't say what it is cuz the gas stations here don't have labels! lol) the car ran 12.1 with a 1.95 60ft and 116mph on the first pass.

Then second pass switched to race fuel the car ran 11.6 with a 1.9 60ft at 116 mph (my friend lifted off at the end cuz the track here is a little sketchy).

No third pass because on the second pass the gearbox casing on the bell housing side cracked.

Moral of the story... I think this car ran very well and we had I believe the intake cam set 11 CAM degrees retarded. Which is a lot and I would guess anyone running that cam straight up would not have a good result. Just a educated guess though.

 

Quick question for you guys! How you do for a MIVEC intake cam if the cam is out of spec? I guess playing with the MIVEC map to cover (if possible) the degrees that is off. Right?

 

Did you test this yourself or is it a assumption? Anyone else who did this test?

 

This truism has been around as long as the hydraulic tappet has existed. In 2008, with cam specs in hand and my engine on the stand with degree wheel mounted, I had an opportunity to check the cam timing my own engine after I made that last post in this old discussion. Indeed I found that my wishful thinking was incorrect. Just as with hydraulic lifters on the V8s in the 'old days', the hydraulic 'pivot' on the 4G63 gave enough to distort the readings just the same.

The lifter must take up all slack in the valvetrain and remain absolutely rigid against spring pressure to allow the follower to transfer the exact contour of the cam lobe to the valve stem. When the engine is running and the lifter has the benefit of oil pressure, this is more or less the case. When the engine is not running and the lifter compresses even slightly against valve spring pressure, this is not the case.

 

Thanks for clearing that up. I am sure lots of people are still measuring without solid lifters. I hope they read this and adjust their way of cam degreeing.

 

I get the impression that few here bother to go through this exercise. Those who do will likely realize what's happening as quickly as I did.

 

I did it when I put together the 4g63 for friends 2g gsx. The hydraulic lifter definitely made everything weird, so I gave up. It was a good idea to double check, but in all reality not really a huge concern in these engines with fixed valvetrain geometry. And especially with how accurately most companies are able to produce camshafts these days, especially Kelford and GSC..