Ls2 408 stroker
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I think a cam change is likely going to be your cheapest option.
Sorry you're still not seeing the results you want. For what its worth, the manton pushrods were a good move.
You coulddd also...sell your top end complete and start fresh with some different heads, 1.7 rockers and 1207x springs and probably wouldn't be out too much in the long run.
The combo you have is probably better suited for someone with a solid roller and a heavy spring.
Sorry you're still not seeing the results you want. For what its worth, the manton pushrods were a good move.
You coulddd also...sell your top end complete and start fresh with some different heads, 1.7 rockers and 1207x springs and probably wouldn't be out too much in the long run.
The combo you have is probably better suited for someone with a solid roller and a heavy spring.
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Hi, Ive just read thru your thread, nice build. My old engine was ls2 454ci 239/254 hyd roller , ported ls3 heads 2.180 intake with fast lsxr long runners and it had 560rwhp. On the same dyno my mate just had his ls3 408 stroker , ported heads with a 236/248 cam and oem intake make 480rwhp . The highest a 408 has made on that same dyno has been 518rwhp So if your getting 500rwhp i think your somewhere in the ball park.
I think the reading you got from your previous engine was on a very generous dyno also, are you on the same dyno with new engine ? Has it been calibrated since you had the previous engine run up ? Dyno's are variable, drive it and see how your butt dyno goes
I think the reading you got from your previous engine was on a very generous dyno also, are you on the same dyno with new engine ? Has it been calibrated since you had the previous engine run up ? Dyno's are variable, drive it and see how your butt dyno goes
I am from Geelong.
I have been using the same dyno for quite a few years.
It's a pro dyne dyno and it reads lower than the others I have been on in the past.
There was a place down here that was reading 12rwkw higher than the one I usually go to.
The one that reads the lowest is the one that is usually the most accurate.
Your mates power figure is about right.
I have the FAST with the long runners so this would make a little bit more.
As stated in the thread I either need to change rockers or maybe go with a cam motion camshaft (with less lift) with the same hardware and see how I go.
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I usually take off 15-20% of power to match what is down here. (when I see it's on a dyno jet)
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From: VA
I have successfully beat the horsepower calculators with my dyno numbers 3 times with my "dyno jet" numbers. My car weighs 3050ish in race form made 563 SAE and trapped 135. Same dyno same car when it made 450 SAE bolt ons it trapped 131. If you take 15% off those power levels it would be way skewed. I think local to me our numbers are pretty accurate.
Originally Posted by bortous
I always thought the US dyno figures are a bit inflated.
I usually take off 15-20% of power to match what is down here. (when I see it's on a dyno jet)
I usually take off 15-20% of power to match what is down here. (when I see it's on a dyno jet)
That there is no change makes me think you do not have a valvetrain instability issue
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From: Melbourne, Australia
I have re-read your thread and what stands out is you say your builder advanced the cam more than what the cam card stated. Advancing a cam brings the power/torque lower in the rev range, torque /power fall off faster in the top end. Usually you run th cam at whats speced.
Im gunna say your cam timing is wrong
Im gunna say your cam timing is wrong
Spanks said it best early on:
- Early posts swear its not valvetrain stability, later posts swear it is valvetrain stability. The graph hasn't shown signs of valve float/instability.
- You've spent on pushrods what a Holly Sniper intake or knock off costs that would put to rest whether or not its an intake manifold problem. Didn't see any resolution to whether or not there was still an intake restriction from the logs. Yes mid-length runners were swapped on, no response on intake restriction. If there was still a restriction then it wasn't the heads that were sent out.
- What is the torque converter slip in high gear through the WOT curve?
- As said a compression test doesn't tell all. Leak-down for starters and need to check for weak spark/injectors.
- Can also measure backpressure easily in the exhaust.
- No info on AFR/spark numbers on the pull.
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I have re-read your thread and what stands out is you say your builder advanced the cam more than what the cam card stated. Advancing a cam brings the power/torque lower in the rev range, torque /power fall off faster in the top end. Usually you run th cam at whats speced.
Im gunna say your cam timing is wrong
Im gunna say your cam timing is wrong
Camshaft came with 1 degree of advance built in and it needed another 2 degrees which it received.
Valve events are correct.
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From: Melbourne, Australia
Mayb im wrong but you cant change the centre line by advancing it more than the cam card states. The centreline is ground in.
Ive seen where a guy dynoed his cam as cam card stated, then dyno'd again advancing it 2 degrees and below 3900 it had more torgue/hp and above it had less with it losing 43nm an 50hp less at 6300rpm
Ive seen where a guy dynoed his cam as cam card stated, then dyno'd again advancing it 2 degrees and below 3900 it had more torgue/hp and above it had less with it losing 43nm an 50hp less at 6300rpm
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From: HTown, Texas
Spanks said it best early on:
- Early posts swear its not valvetrain stability, later posts swear it is valvetrain stability. The graph hasn't shown signs of valve float/instability.
- You've spent on pushrods what a Holly Sniper intake or knock off costs that would put to rest whether or not its an intake manifold problem. Didn't see any resolution to whether or not there was still an intake restriction from the logs. Yes mid-length runners were swapped on, no response on intake restriction. If there was still a restriction then it wasn't the heads that were sent out.
- What is the torque converter slip in high gear through the WOT curve?
- As said a compression test doesn't tell all. Leak-down for starters and need to check for weak spark/injectors.
- Can also measure backpressure easily in the exhaust.
- No info on AFR/spark numbers on the pull.
On The Tree
Joined: Jun 2019
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From: HTown, Texas
Mayb im wrong but you cant change the centre line by advancing it more than the cam card states. The centreline is ground in.
Ive seen where a guy dynoed his cam as cam card stated, then dyno'd again advancing it 2 degrees and below 3900 it had more torgue/hp and above it had less with it losing 43nm an 50hp less at 6300rpm
Ive seen where a guy dynoed his cam as cam card stated, then dyno'd again advancing it 2 degrees and below 3900 it had more torgue/hp and above it had less with it losing 43nm an 50hp less at 6300rpm
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Camshaft was a custom spec at a 242/257 113lsa +1.
In order to get the Valve events where we want them at ivc 51 and Evo 65 and 110 icl we needed the extra two degrees of advance.
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I'm a great listener so you got that wrong.
On The Tree
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From: HTown, Texas
I agree, you have been great at listening to bad advice. Stop wasting your money, stop throwing parts at it, and do a proper check for dead cylinders. You missed an opportunity the last time it was strapped to the dyno; your "tuner" could have made a series of pulls, each with a different injector unplugged. Any pull that didn't lose power would have confirmed a dead cylinder.
While you're at it, get a different "tuner", this one is a hack! Didn't he say that the data logs showed a restriction after the first test? So you went out and bought the shorter runners (which was a dumb idea anyways). How did that work out for ya?
Then he says that it must be the lack of spring pressure because someone didn't shim the springs enough, so you let him shim the springs. How did that work out for ya?
Lastly, he says it must be valvetrain instability, despite no signs of it on the graph, but you went and bought the stiffer pushrods anyways. How did that work out for ya?
How many more chances are you going to give this "tuner" before you wise up?
While you're at it, get a different "tuner", this one is a hack! Didn't he say that the data logs showed a restriction after the first test? So you went out and bought the shorter runners (which was a dumb idea anyways). How did that work out for ya?
Then he says that it must be the lack of spring pressure because someone didn't shim the springs enough, so you let him shim the springs. How did that work out for ya?
Lastly, he says it must be valvetrain instability, despite no signs of it on the graph, but you went and bought the stiffer pushrods anyways. How did that work out for ya?
How many more chances are you going to give this "tuner" before you wise up?
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I agree, you have been great at listening to bad advice. Stop wasting your money, stop throwing parts at it, and do a proper check for dead cylinders. You missed an opportunity the last time it was strapped to the dyno; your "tuner" could have made a series of pulls, each with a different injector unplugged. Any pull that didn't lose power would have confirmed a dead cylinder.
While you're at it, get a different "tuner", this one is a hack! Didn't he say that the data logs showed a restriction after the first test? So you went out and bought the shorter runners (which was a dumb idea anyways). How did that work out for ya?
Then he says that it must be the lack of spring pressure because someone didn't shim the springs enough, so you let him shim the springs. How did that work out for ya?
Lastly, he says it must be valvetrain instability, despite no signs of it on the graph, but you went and bought the stiffer pushrods anyways. How did that work out for ya?
How many more chances are you going to give this "tuner" before you wise up?
While you're at it, get a different "tuner", this one is a hack! Didn't he say that the data logs showed a restriction after the first test? So you went out and bought the shorter runners (which was a dumb idea anyways). How did that work out for ya?
Then he says that it must be the lack of spring pressure because someone didn't shim the springs enough, so you let him shim the springs. How did that work out for ya?
Lastly, he says it must be valvetrain instability, despite no signs of it on the graph, but you went and bought the stiffer pushrods anyways. How did that work out for ya?
How many more chances are you going to give this "tuner" before you wise up?
I'm going to see him personally next Thursday.
All my contact has been via text.
I will update this thread once I have new information.
As stated cylinders were checked. There are no dead cylinders.
This was done at the beginning.
Even Patrick Guerra said it is those yella terra rockers and that camshaft I have which are most likely causing these issues.
And also having too much lift. He also says, the valvetrain setup I have is more suited to a LLSR and would work really well with it as it's far more stable.
I am also the one that decided to go the higher ratio and heavier rocker but I was advised against it and still went ahead anyway.
Also the camshaft, was never intended for a higher ratio.
I called up the camshaft place a while ago and told them my issue and their first response was to take off those **** heavy rockers, go back to a stock ratio GM rocker or get the ultra lite pro YT in 1.7.
This will resolve the issue I am told.
Spring choice is good though.
I will see what happens.
Most likely by the looks of things I will probably end up going the LLSR as it's the easiest way of doing it.
But we will see.
I can always sell the other parts.
