I remember my 4.8 not liking getting up anywhere past 5000. I'm concerned with losing torque with a such a high rpm setup, I'm gonna have a lot of extra weight
CK5
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91' Blazer 6.0 LS, 4l80e, Nose swap, Full Top Conversion, and Restoration
- Thread starter Coontail
- Start date
Summer DD, go fast on the on-ramp, and capability to tow
I’m running the BTR stage 2 with 1800 stall. Still needs tuning but it feels strong. It won’t win any races but there not lack of power. I think with a custom tune it’ll be a monster. I also have a little bump in compression (9.8:1). 4:56 gears 4l80e and 37s
Is that static or dynamic compression? I'm also concerned with detonation
An excuse to spend more money? I'm in!
Just kidding, but I will be looking into that for sure
Just kidding, but I will be looking into that for sure
static
So I ended up demoing engine analyzer pro, definitely something worth checking out. I've decided on the BTR Stage 2 V2 Truck Cam, it gives more power across the board compared to the stage 3, XR269, and TR224. I still don't know if it'll detonate on the 706 heads, I still really want to run them
What kind of numbers is it putting out? Just curious. I’m guessing mine, with a proper tune, should be well into the 450-475 hp/tq area. That’s just based off some similar engine builds.
I'm getting 439 hp @6000 and 422 lbs @5000 that's with the higher compression heads
Just want to chime in since something isn't making sense here. You are saying a shorter duration cam will make more power even higher in the RPM range? Even with stock LS heads I doubt that, so something in your demo data seems off. Simulation software is a great tool but frequently can output results that don't make sense, the output is only as good as what is input, and even then there will be limitations, I frequently see output curves I don't believe based on what I've seen in reality, you have to beware when something doesn't seem right.
Also, what do you mean "detonate on the heads"? Do you mean detonate because the heads have a smaller chamber or something? If you are worried about detonation just punch the numbers in and see what the dynamic compression is with each cam and those head combustion chambers. My app will do that easily if you know the head and piston cc, etc. Then you can determine if the dynamic is too high for pump gas.
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My bad in the upper rpm range it was pretty closely matched but from the mid-range down it was making more. This is just off the top of my head right now though so I could be wrong, I'll put a picture of the power curves on here later
Yes on the heads, the 706's will bring the dynamic compression up a full point (~9.25:1) according to https://www.gofastmath.com/Compress...atic_And_Dynamic_Compression_Ratio_Calculator
But on engine analyzer it was coming out almost a full point lower. I found my DCR varied with every calculator I tried so I'm not sure how much I can trust the online ones. I'll have to fiddle around with the program some more tonight
Where can find your app?
Well I disagree with using the intake closing at .050" lift to calculate dynamic compression, you aren't likely to create compression when the valve is open .050". I use the advertised duration, which is closer to when the valve actually closes. Theoretically if the piston speed was high enough it could start to compress, but you are more worried about detonation at lower RPM with high load, when piston speeds are slower. I wouldn't be afraid to use up to 8.5 dynamic with an aluminum head LS combustion chamber, and my calculator. Using the number at .050 is more conservative, but I know from experience that it's safe to use the advertised number assuming your fuel and timing are within a reasonable range. Now I'm sure there are people out there with a manual transmission and 3.73 gears and 40s that release the clutch at 1100 RPM in 4th gear and 3/4 throttle. Those people might be pushing it too far, but for most normal applications it will be fine.
My Gearhead apps can be found in the link in my signature or you can use the online calculators. My dynamic compression calculator uses pure trigonometry and geometry to calculate the dynamic compression based on how the engine works, there is no way around this math (unlike HP numbers and weather and wind effects, etc). So the only way to change the results is if you use the wrong numbers or different intake closing points. I also include a cam math calculator so you can easily find the advertised intake closing point from the cam specs if its not already given.
So I downloaded the app but after entering all the info for a stock lq4 I'm getting 10.68:1 as a static cr. What am I doing wrong?
Wow, that was fast, I hope you like it, I see two things so far...
The compressed gasket volume is likely a lot more than .06 cc, it's probably more like 9 cc or something. Usually I can find the exact numbers from the part number and the manufacturer site or google.
Also, the slider was moved so the piston is above the deck at TDC, this is highly unlikely unless you decked the block significantly. It's usually below deck from the factory. Sometimes as much as .020" but the best way to know is to measure your engine if you have the heads off.
Let me know if you have any more questions.
The compressed gasket volume is likely a lot more than .06 cc, it's probably more like 9 cc or something. Usually I can find the exact numbers from the part number and the manufacturer site or google.
Also, the slider was moved so the piston is above the deck at TDC, this is highly unlikely unless you decked the block significantly. It's usually below deck from the factory. Sometimes as much as .020" but the best way to know is to measure your engine if you have the heads off.
Let me know if you have any more questions.
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Estimated power curves with 706 heads and BTR stage 2 V2 cam
Factory stall is at 2100 - 2200 so I think I might just stick with it
Factory stall is at 2100 - 2200 so I think I might just stick with it
Sweet! I’m loving that torque curve! Wonder if my 1800 stall would make much difference.
Power seems low still. A buddy has a stock 6.0 bottom end, running a little bigger cam than the stage 2, FAST intake and 706 heads and made around 520hp/500ftlb
1800 would be perfect!
