| acammer |
11-08-2022 06:39 AM |
Quote:
Originally Posted by morepowerjoe
(Post 11250538)
Ok guys it's been a wild ride. Let me say this first, I am in no way blaming anyone for the results I'm about to post it's just what it is. So after a lot of tuning and I mean a lot, my set up only made 455 whp @ 6300 and 429 wtq @ 5100 with the Cold Air Inductions lid cover removed. Now that may seem pretty low as compared to others with the SS3 VVT cam and really low once you figure that I had made 438 whp originally with the old grind SS1 VVT. So I paid the tuner again to pull the cam back out to verify that it was indeed a SS3 VVT and it was of course. But I did build the engine for boost and now it's ready for it. One of the things that may have kept it from making a little more power was the compression ratio because I was told by the machinist to use a ls9 gasket which is .054 thick which then I found out he had figured the 10.94:1 ratio with .040 gaskets. Big goof on him for that so my end compression ratio ended up being 10.57:1. Now I can always change those out to boost the compression if I decide too in the future which I probably will. Another problem we encountered was the pushrod length. We started out with a 7.375 because I thought after .035 removed from the heads that's about as much lifter preload as I wanted but something was off because the vvt wasn't working. After measuring with a pumped up lifter with no preload it came out to being 7.3. So we went ahead with the maximum amount of preload at .125 and put the 7.425 back in and magically the vvt started working but they also said that the cam phaser had fallen apart when they removed it so whatever. I think they just changed it because the vvt wasn't working. What I think was really going on was the lifters were using so much oil pressure by having too much preload and with my mishimoto oil cooler that there just wasn't enough oil pressure to activate the vvt. I was reading up on lifter preload and some say that by adding a lot of preload the lifter acts like a slow leakdown lifter and doesn't have to use as much oil. But that's just my take on it. Also after a few dyno runs without the vvt not performing as expected they then wanted to pull out my short runners from the Fast intake and out put the long runners back in which we did and I think it would have moved the peak power to a higher rpm with the short runners being that wasn't the problem with the vvt not working. So I have a few things to work on in the future but these are my results with my combination of parts that I've installed. And one more thing I would like to say is the amount of support that I received from Andrew Cammer at GPI was phenomenal and I sincerely thank him for his help through all of this.
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Hey man - I respect the honesty. We've talked a LOT the last few weeks, and I know it's not the results either of us were expecting, and definitely a little disappointing when you compare to what other similar builds have done. Couple of notes on what you shared (you already know, but for the other viewers that haven't been in our mile long e-mail chain).
- Compression - for something that's planning on seeing boost in the future, staying with a modest 10.5:1 is reasonable. From a naturally aspirated perspective, that definitely was a missed opportunity to make some more power. It's not less than stock - and we would have expected it to perform similarly to other SS3-VVT builds with stock compression.
- Lifter Preload - Realistically, the lifter behaves pretty much exactly the same, no matter where in it's travel it is preloaded to. For a OEM style lifter, we would typically target anywhere from .050" to .130" for preload, and either set of pushrods should have delivered essentially the same results. Lighter preload does not consume additional oil pressure. It is true that heavier preload reduces the potential for squish in the lifter, and it will act more like a solid lifter - however with the modest valve-spring pressure in this combination, I don't believe any power differences were related to preload and pushrod length.
- Phaser Functionality - Prior to above, I had not heard that the cam phase in the car had come apart. That explains all the problems with the VVT early on in the tuning phase of this build - I have seen many more get trashed than successfully repaired once you let that spring out.
- Prior Cam - it's important to note that the SS1-VVT cam that came out of this car was what is now our SS2-VVT camshaft, and we've actually scaled back the current SS1-VVT to be a bit better behaved with the stock converter. All that to say, in general, I expect our SS2-VVT to gain about 15whp on our SS1-VVT, and the same going from our SS3-VVT over our (and your previous) SS2-VVT.
- Intake Manifold and Runner Length - The FAST LSXR has never proven itself on the LS3, in my opinion. They are a great cathedral port manifold, and I run one myself for my raised rectangle port LS7 heads, but the LS3 variant just doesn't really make any better power than a ported and rod-modded OEM intake. It's not a bad manifold, but it doesn't really show much value on milder LS3 combinations. The runner length is math - a given runner length will produce it's best resonance and power in a given rpm range. The long runners match up with where the camshaft you have wants to live. The mid and short runners for the LSXR are spicy, they will consume substantial bottom end and midrange power to move the power curve up over 1,000rpm higher. That's not where the rest of your combination wants to live, and so I was not surprised that they didn't perform. Definitely the long runners are the way to go for almost all combinations.
There are a lot of factors to consider on this one. Even after pouring over them all, I'm a little surprised that it doesn't make more power. The rebuild looked to be solid and done with care, and I've spent time talking with your tuner, who is experienced with plenty of demonstrated excellent results on this platform and even with this camshaft. Nobody knows where that last 15whp is. Overall, the gain is really not far off what I'd expect, based on what the last setup put down. The motor is fresh, and running great, produces a big wide VVT power curve, and despite whatever we all hoped the dyno would say, this should run very well on the street and the track. I know, first hand, all too well what it's like to chase power and ET numbers - but at the end of the day, we're chasing smiles per gallon. I think this setup is gonna deliver big on those! |
