Supra Forums banner

481 - 500 of 515 Posts

·
Flying Dutchman Pilot!
Joined
·
2,172 Posts
Next question. Am I the only one that has noticed an error on the cam card for the exhaust cam or did other GSC S2 users get a different card then me? The total duration at .040 is listed as 240 degrees. It says the exhaust cam opens at 58 BBDC and closes at 2 BTDC.



If you follow these numbers on a degree wheel you end up with 236 degrees total duration not 240. Remember the motor spins clockwise. Follow the degree wheel from point to point and you will count 236 degrees.



I checked the duration of the cam in the motor and it is 236 degrees not 240 like the card states which is correct if the opening and closing angles on the card are correct. This also makes the overlap 6 degrees not 10 assuming the exhaust opening and closing angles are correct. I just want to make sure the error is in the total duration on the card and not one of the opening and closing angles(or both) as I don't want to have to go in and do this again.

In any case, with my dial indicator matching the angle of the valve stem, my intake cam was dead on but the exhaust was opening at 49 degrees BBDC, effectively giving me an overlap of 15 degrees, not the 6 this cam is supposed to have. Ultimately I think I have nailed my wideband reading issue but I will know for sure next time I get on the dyno. I currently have the cams dialed in as per the card specs now. Hoping at least the opening and closing angles are correct. I called GSC today and got the Pat answer of "its normal and you're probably seeing timing belt and lash variances." This didn't even make sense since the numbers on the cam card not adding up have nothing to do with my engine variances. Whatever, again, I just want confirmation the valve opening and closing angles on the card are correct and the error was the spec'd total duration.
 

·
Registered
Joined
·
1,695 Posts
Joliroger4 did you notice this during installation or after dyno tuning and then went back to see why it's not running right? If so do you have data to share on the before and after, if so where was the power curve affected before and after the change? Thanks! Good catch, I had mine set to the card at a machine shop that built a special jig to correct an angle on TDC marker. These guys are engineers and am surprised they didn't catch it. It took them about three hours and they said it was difficult to set. I have about 10hg of vacuum at idle. What amount of vacuum do you read at idle now?
 

·
Flying Dutchman Pilot!
Joined
·
2,172 Posts
I've been having an issue with the truck for the last 2 months with the wideband(what I believe to be the overlap affecting the A/F that I posted about above). We got the motor to pull clean but with the erroneous A/F numbers we were not comfortable tuning the car so we stopped there. Of the clean pulls the best number we got 669 at the wheels with stock cam gears. I can post my after numbers once I am off the dyno but it wouldn't be a fair comparison since the A/Fs probably wont be consistent between pulls, not to mention we will be changing a bunch of things once we confirm the wideband issue is gone. I'd have to look for the sheet. The truck pulls 12 in/hg cold and 14-15 once warm. It idles at about 1000rpm. Much less emissions and lope once I degreed them. It is a pain to get the indicator on the bucket properly and match the right angle. I had to make a special end for the indicator to do this. It is also nice having an ati damper with a degree wheel already etched in it as well as an indicator permanently on the motor indicating true tdc. Once you have these things in place, degreeing the motor was a breeze.

Just an update to this. I got a call back from GSC and was told the exhaust valve opening angle is indeed 58 BBDC but the error is the closing angle which should be 2 ATDC not BTDC. This yields a total duration (@ .040) of 240 degrees. I don't totally believe this as I am confident of when I checked my cams the scale on my damper went 236 degrees but I am not too concerned with that. The opening angle was correct and that was what my exhaust cam adjustment was based off of. Wherever the closing angle lands is where it lands.
 

·
Registered
Joined
·
150 Posts
I have gsc2 zero'd out and it sounds identical to this



i totally agree, and even mine sounded way too smooth

but thats ok, like i just said, i worked on my idle.

ive actually changed it slightly since this video, now it kind of alternates between roughness and 50% of the time it starts loping like a 1 cylinder (like it constantly is in the video).
so it sounds absolutely vicious and there is no mistaking monster cams when you hear it.


in my experience, the richer it is with gsc s2, the smoother it will sound, and the timing affects it too. +/- from 15 degrees will make it more choppy. mine idles the strongest around like 18 degrees timing and it sounds the best when AFR gets up leaner than 15:1.
definitely stay away from 12/13 to 1 AFR with retarded timing, it will sound OEM.

as we speak, mine is set to fluctuate between 14.7-15.5 AFR (just a touch richer than in the video, i didnt like how it was idling like WHUP WHUP WHUP WHUP WHUP. im a man that prefers blub-blub-blub-blub WHUP WHUP WHUP blub-blub-blub-blub), and i am using vlad's ignition hunting techniques (look on youtube "how to tune aem v2")--where it retards 10 degrees if idle is off by 100 rpm, and advances 10 degrees if it drops below 100 rpm, and my deadband is set to 100rpm as well.
my timing is also around 18-19 degrees at the rpm/vacuum area in which the car idles.
 

·
Registered
Joined
·
583 Posts
I am putting my engine back to gether with S2 cams. I plan to do a compression test and was wonder what I should see for cranking compression. The motor is stock C/R. I know before I pulled the head I saw 155-160 on a cold engine.
 

·
Registered
Joined
·
4,692 Posts
140 +/- 10 psi if you are lucky. These engines do not put out high cranking compression, and it decreases with HP cams. I would not even test it.

A leakdown test is much more informative, just as easy, and doesn't wear down you battery or cylinder walls. Just need a tester.

Al
 

·
Registered
Joined
·
1,910 Posts
What turbo kit is this Alpha love the dyno and how safe this set up should be if not pushed to much on stock block.

Is the higher number on the Dyno Race gas or E85
 

·
Premium Member
Joined
·
4,435 Posts
What turbo kit is this Alpha love the dyno and how safe this set up should be if not pushed to much on stock block.

Is the higher number on the Dyno Race gas or E85
ETS. We're a dealer for them so if you're interested e-mail us for pricing.
 

·
Registered
Joined
·
5 Posts
Super Amped up to get my car back From induction performance! Alpha and Victor are great guys. Alpha tuned my 6466 and was able to get me 774 @ 36 psi on my stock motor and GSC 2 cams.
 

·
Registered
Joined
·
18 Posts
If I have 1mm oversized ferrea valves and just bought 10:1 pistons do the pistons need to be cut to accept the larger valves?
I'm buying gsc s2 cams as well.
Any info would be great thank you
 

·
Registered
Joined
·
160 Posts
The GSC 1 is the way to go if you want drivability, although i've heard the S2's aren't too bad either. I am getting dynoed mid-jan and I might be putting in the S2's by then so i'll see what numbers I can get.
 

·
Stock Twins King
Joined
·
4,546 Posts
Curious to hear feedback because with my modified hybid turbos, I am not considered a "single". I have HKS 264's now, and currently building with CP 10:1 pistons and Manley rods. So I am wondering if it makes sense to switch to S1s. Mostly because of the new piston set up. At the 1/4 I am at 139mph at 8000 rpms in 4th gear. Don't know if the 10:1 will change any of this. I am good to about 8500 on the rev. It appears that the S1s are bigger than the 272's. I figured the 272s were too big for my set up, but the design of the S1s looks appealing.

Stu
 

·
Registered
Joined
·
13,584 Posts
...It appears that the S1s are bigger than the 272's. I figured the 272s were too big for my set up, but the design of the S1s looks appealing.

Stu
Stu,
Not sure what you mean by "bigger" but the S1's are 269 duration so less than 272's. But GSC's have great lift and an aggressive profile. HKS 272's and 280's have 9.3 lift; HKS 264's have 9.0 lift.

S1 Specs gsc-6030S1
Intake 269 Duration 9.90mm peak lift, 108 degree Centerline
Exhaust 269 Duration 9.90mm Peak Lift, 114 degree Centerline
 
481 - 500 of 515 Posts
Top