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GR-RRR!
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I thought I'd start another thread since my original rocker thread went about 20 different directions. To recap for those who haven't been following along, I installed:

-Comp Cams Pro Magnum 1.8 ratio roller rockers
-Lunati dual springs, retainers, seals locks and spring perches (the springs provide about twice the stock LS2 spring pressures)
-Comp Cams Magnum Chromoly 5/16" 7.400 length pushrods

To accommodate the new rockers I also had to install valve cover spacers and I put on Dragon Fire 8.5mm spark plug wires along the way mostly for looks (they are orange). I also found that the balancer bolt was loose so I installed a new GM bolt, drowned it in red LocTite and installed it per the shop manual.

I had broken in the springs on Saturday but hadn't driven the car yet with the new rockers. Weather wasn't great today but it stopped raining and got into the mid 40's so I decided to take it for a spin. I have to take it in for an alignment tomorrow due to the recent header install so I thought it would be best to drive it a bit before tomorrow in the event anything were to crop up due to the rocker install.

At first I drove very conservatively to get the engine warmed up. Even once it was warmed up I was a little tentative about revving it too high, I'm always nervous after I've been inside an engine. The only problem I noticed was that one of the headers was buzzing against one of those little brace studs at certain RPMs but at least I knew what that was. I must not have trimmed it down far enough. Minor problem and it seemed to go away after the car warmed up. At first I got it up to about 4k in first and second. No problems, seemed happy. Then I ran it up to about 6k in first only, no problems. Then I drove for a little while further looking for a good place to get after it. I went quite a ways, just getting into it a little at each stop. I drove out to my favorite spot in Mexico, turned around and drove real slow to get past a jogger, didn't want him to think was trying to run him over!

Then I banged through first through fourth hitting redline (6500, rev limiter at 6700) in first and second and about 6200 in third and fourth. It seemed REAL happy. If I were to raise the rev limit I'm sure it would pull real hard well beyond redline but since the LS2 cam is done by redline I don't see the point. But the breathing capacity is there and there was no valve float felt at all. It pulls very hard all the way to redline. I really noticed the improvement in the midrange and top end, not much benefit down low I could detect. I only drove it once after the long tubes went in, similar weather that day and I can definitely tell the rockers have added to the package quite well. The combo of the rockers, headers and FAST 102 really seem to be a good combo for a stock long block. I'm sure the tune helped a bunch too.

The sound didn't really change, but it does feel more rev happy, slightly more aggressive. Better throttle response just off idle. Maybe that's all in my head but whatever the case I'm happy with the results.
 

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2006 GTO
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Nice! I felt a great improvement from 3500rpms to redline after the FAST 102 and 1.8's. Without the tune being changed from just headers and a CAI my car made 394hp/392tq and it pulled hard. After the tune was cleaned up it made 409hp/402tq and absolutely screams. Now all you need is 3.91 gears from Oz!

Edit: Your comments are spot on. It definitely does rev faster and the off idle throttle response is much improved. It really feels like the engine is breathing properly.
 

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GR-RRR!
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Discussion Starter #3 (Edited)
Your comments are spot on. It definitely does rev faster and the off idle throttle response is much improved. It really feels like the engine is breathing properly.
The FAST helped with that to a great extent. Then the LT headers helped more and I feel that rockers took that aspect even further. These have all be modifications where I could tell right away things had improved at each step. The LS2 cam is not particularly remarkable in any way but it is clear GM saddled it with a crappy intake manifold, crappy exhaust manifolds and lackluster lift numbers not to mention a WAAAAY overly conservative tune. But then GM has done this crap forever.

One ancient example I can site from intimate experience is the L79 which was the 350hp 327 from the mid-1960s. It is a really rip roaring engine but was saddled with restrictive exhaust manifolds and a weak tune. The biggest factory limitation though was the mechanical advance in the distributor. A good rule of thumb for engines of that era are to have mechanical advance that is all in at least by 3000 RPMs. The mechanical advance they installed on the L79 didn't deliver full advance until about 500-600 RPMs prior to redline. This makes the engine really soft at low RPMs and dramatically weakens the midrange punch which is a bad deal since it is a relatively small engine trying to move a fairly heavy car (a 65 Chevelle in my personal experience). Just changing the mechanical advance springs makes it an entirely different beast.
 

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One ancient example I can site from intimate experience is the L79 which was the 350hp 327 from the mid-1960s. It is a really rip roaring engine but was saddled with restrictive exhaust manifolds and a weak tune. The biggest factory limitation though was the mechanical advance in the distributor. A good rule of thumb for engines of that era are to have mechanical advance that is all in at least by 3000 RPMs. The mechanical advance they installed on the L79 didn't deliver full advance until about 500-600 RPMs prior to redline. This makes the engine really soft at low RPMs and dramatically weakens the midrange punch which is a bad deal since it is a relatively small engine trying to move a fairly heavy car (a 65 Chevelle in my personal experience). Just changing the mechanical advance springs makes it an entirely different beast.
kinda wish i was arund back then just so i could have lived in the era of cool little modifications like that.
 

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I guess this is similar to putting 1.6 rockers on a SBC, but with much-better flowing LS heads. Good to hear you can feel an improvement from this mod!
 

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GR-RRR!
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Discussion Starter #6 (Edited)
Not quite the numbers I was hoping for but it improved across the entire RPM range. And the improvements feel like much more SOTP than the dyno shows. I very much do like how it drives now, much more midrange. And look how flat that torque curve is. The first three pulls on the graphs are 3rd gear pulls just to check the tune.

HP: 387
TQ: 390

500838
500839


Also, the tuner was using the very latest Dyno Jet software. He says every time they update the software numbers go down. FWTW. He laughingly said if he were to go back to the original software he had when first got the dyno it'd be showing 450 or more. :D Anyway, software has been updated at least three times since I was previously on the dyno with this car. He did adjust some of the timing, but the fueling was fine. He said he could have added more timing to gain 3-4 more HP but that would be pushing it out of the conservative range.

Best part of the day was the alignment. He was able to give me 1.3 negative camber up front. The rear toe was off quite a bit in back. Steering wheel is dead straight now. He was able to move the rack over. This is good since it was just barely touching a header tube. I've noticed the driver's side header is occasionally buzzing against the frame brace stud so I need to remove it completely I guess (I only cut off about half of it).
 

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GR-RRR!
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Discussion Starter #8
One take away from all this is probably that JBA shorties and high flow cats are pretty good stuff.
 

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Well, shit. I don't know anything about the software version at CSP but if you have confidence in the tune and it runs it's ass off then that's awesome. Enjoy!
 

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I know I did. The SOTP feel after about 2500 is completely obvious and then it pulls hard all the way to redline. I mean, just look at that torque curve. I know the LS2 torque curve is generally like that, but it revs so much quicker now while accelerating. After we get a few more rains to clean the roads off I need to go to Mexico with my G-Tech and see what I can do. No tracks really nearby, but the last time I was at the track my G-Tech was within .01 of a second of the timeslips.

The other nice thing is that there are no blips in the HP curve so the springs are doing their job admirably.

I do think I have a rear main seal leak though and that bums me out. I replaced the seal when I did the clutch.
 

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GR-RRR!
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Discussion Starter #14
Maybe, but the dyno is just a number. At least I know I made progress. EXPENSIVE progress but at this point I'm just having fun. And really, when it was all said and done a friend GAVE me a set of LS7 heads which I sold which has paid for everything thus far and I still have some funds left over so all this (headers, rockers) hasn't really cost me anything. Thanks buddy Jim!
 

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Nicely done!
Went to your website, mighty Pretty car! And nice presentation, thoughts and comments.
Super nice Dyno numbers, esp "Torque". I think I read about your mods long time ago, Super Chevy? I can't remember exactly but I think they also did new lifters. Reason it caught my eye was: "Bang for the Buck", good results for pennies on the dollar.

You are making son and me rethink our build! Was all set to pull trigger and then this.
 

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My Chevelles have both been in Super Chevy a few times and those same articles have been recycled on their website a few times. They've never done anything about the GTO there though.
 

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You know I woke up and thought about this thread and your dyno numbers. Are you able to see the Air/Fuel ratio throughout the RPM, the timing, anything? Can you scan for KR? I have dual autometer gauges that scan for about 100 different things so I can see these things as well as my Wide Band that's plugged into the drivers side rear O2.

I feel like even with this "software" talk there is something not right about the power you put down. When I was at CSP he was adjusting all those things and others in small increments of about 500rpm it looked like and he did about 10 pulls. But even with the unchanged tune from 2013 it made 390's on hp and tq. I feel you should be making more is all. Is the AFR between 12.7-13.0 with as much timing as you can without getting KR? Stuff like that I would want to know.

Edited for spelling.
 

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One take away from all this is probably that JBA shorties and high flow cats are pretty good stuff.
the factory manifolds flow as much as the shorties, your power gained is from the high flow cats. I did those on my car with the factory manifolds and that was the biggest difference.
 

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GR-RRR!
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Discussion Starter #20
You know I woke up and thought about this thread and your dyno numbers. Are you able to see the Air/Fuel ratio throughout the RPM, the timing, anything? Can you scan for KR? I have dual autometer gauges that scan for about 100 different things so I can see these things as well as my Wide Band that's plugged into the drivers side rear O2.

I feel like even with this "software" talk there is something not right about the power you put down. When I was at CSP he was adjusting all those things and others in small increments of about 500rpm it looked like and he did about 10 pulls. But even with the unchanged tune from 2013 it made 390's on hp and tq. I feel you should be making more is all. Is the AFR between 12.7-13.0 with as much timing as you can without getting KR? Stuff like that I would want to know.

Edited for spelling.
Yes, he was monitoring all that. He had a wideband installed in a header collector. There is a convenient extra bung just for that use. AFR is perfect. I told him about the buzzing against the brace stud and he specifically looked at KR due to that and saw none. He typically tunes fairly conservatively. He gets the AFR all set and then plays with the timing. He starts real low and then adds 2 degrees to timing and does another pull. If it adds 5-10 HP he adds 2 more degrees and runs it again. When he reaches a point where adding 2 degrees only adds 2-3 HP he backs it off. He says this leaves it shy of maybe 5-6 HP overall doing it this way but this doesn't threaten it with detonation and all the trouble that can create.

But like I said before, it's just a number. I gained with these upgrades, that's the most useful information. On paper it may only be 9-10 HP, but I can most definitely feel the difference and it is mostly in the midrange and top end where I can actually use it and get the power to the ground. The LS2 cam is kind of a soft cam, but it is what I have and plan to stick with. If I ever do decide to do a cam, I already have good rockers and springs and I'd just have to choose a cam that would work with them. One other thing, with the stock valve train I never felt I experienced valve float, but it is most definitely more firm up top than it was.

Something else just occurred to me looking at the new chart: at the strip I'm shifting waaaay too late. I have my shift light set at 6500 so I'm shifting at 6500. I should be shifting closer to 5800-6000. That alone would probably improve my 1/4 mile times. Power doesn't drop off a cliff, but I've been taking it well beyond the power peak of the cam. I learned with my old Chevelle that winding the engine out beyond the power peak was making me slower. I'll have to try to remember this my next time out.
 
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