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Need Help determining a problem... car falls on its face at 6000 rpm

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Old 02-16-2011, 08:25 PM   #21
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My old cam tailed off at 6k as well.. I thought it was an issue of not enough cam for my engine...

I'm starting to wonder if its an issue with an improperly marked timing set possibly
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Old 02-17-2011, 02:56 AM   #22
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Speculation:

Those cam numbers don't mean much. What are the rest of the cam specs, 0.2? Heads max flow at what lift?

CAM :
If thats a lazy lobe that is not quick on the ramps, you are going to kill off massive compression.

VACUUM
what is the vacuum of the engine at WOT where it starts to fall? Keep in mind 112s peak hard fast, then take a dive.

LOBE STYLE
If their cams are comp LSK lobes, I say no cam issue, otherwise I'm looking at the cam lobe lobe style more than duration as a potential problem in this case.

TUNING
tuning can be a big deal. If the engine doesn't take off good at low rpm, its not going to wind up as well, ie, won't take in as much air. The torque curve, seems to drop too quick after the max torque is attained. Makes me wonder about AFR or spark values in this area without touching top end tuning data.

CRANK CAM GEAR
which degree mark did you line up the crank gear on?
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Old 02-17-2011, 11:58 AM   #23
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It is not a cam lobe issue...
112 lsa does not fall off like a rock at 6k on a big cam
If you knew who I was you would know its not a tuning issue

And I honestly believe its an issue with the timing set.
It acts like its off by a tooth... even though 3 people saw it dot to dot.
Cam degree wheel will tell for sure when I crack it open next week
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Old 02-17-2011, 12:19 PM   #24
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my decked out 383 is doing the exact same thing, trickflows, 242/250 620 110 camfast 102 1 7/8 headers 11.8 cr etc. I have my cam advanced a bit and think that is the problem, but also think my 5200 stall in the th400 may be doin it too, dont wanna tear the engine apart for no reason. 27 degrees timing low 13 afr. let us know what u fin out
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Old 02-17-2011, 01:43 PM   #25
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sound engineer if your running a single chain im selling a new lower adjustable gear as mine was degreed ok straight up. just sayin.
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Old 02-17-2011, 06:40 PM   #26
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The level of care you do in your tuning needs to be applied to your engine also. Start with the basics, degree your cam and measure your pushrod length. Do it right do it once. I've seen a lot of people with disappointed setups and they all have 2 thing in common: So and so told them that 7.xx p-rod length would be ok and I installed my cam dot to dot! If you rule out these 2 issues I would look into your lifters as you may be collapsing them at high rpm. Seems unlikely but those are fairly agressive springs for a hydraulic roller cam.
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Old 02-17-2011, 07:32 PM   #27
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Quote:
Originally Posted by disc0monkey View Post
sound engineer if your running a single chain im selling a new lower adjustable gear as mine was degreed ok straight up. just sayin.
Negative ghostrider..
This has a brand new manley double chain in it
you don't do a single when you mess around with what I'm doing..
There's gonna be 500hp of Nitrous on this motor later this year and a supercharger by early next year

Last edited by soundengineer; 02-17-2011 at 07:37 PM.
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Old 02-17-2011, 10:05 PM   #28
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dam your going north of 900hp?
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Old 02-17-2011, 10:23 PM   #29
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Quote:
Originally Posted by disc0monkey View Post
dam your going north of 900hp?
Plan is 10's on motor, low 9's on spray, 8's with all of it plus supercharger.

And I almost forgot.... all of this in a daily driver with fully functional Air conditioning... and a passenger seat to haul a hot girl around in.
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Old 02-18-2011, 07:42 AM   #30
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got logs?
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Old 02-18-2011, 08:46 AM   #31
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Very well said I had an instructor in school that would say when we had diffculty solving a problem "It always goes back to basics"

Quote:
Originally Posted by Nitroused383 View Post
The level of care you do in your tuning needs to be applied to your engine also. Start with the basics, degree your cam and measure your pushrod length. Do it right do it once. I've seen a lot of people with disappointed setups and they all have 2 thing in common: So and so told them that 7.xx p-rod length would be ok and I installed my cam dot to dot! If you rule out these 2 issues I would look into your lifters as you may be collapsing them at high rpm. Seems unlikely but those are fairly agressive springs for a hydraulic roller cam.
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Old 02-18-2011, 10:46 AM   #32
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And I almost forgot.... all of this in a daily driver with fully functional Air conditioning... and a passenger seat to haul a hot girl around in.
Fix the A/C and she won't be hot anymore.
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Old 02-18-2011, 02:18 PM   #33
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Quote:
Originally Posted by Nitroused383 View Post
The level of care you do in your tuning needs to be applied to your engine also. Start with the basics, degree your cam and measure your pushrod length. Do it right do it once. I've seen a lot of people with disappointed setups and they all have 2 thing in common: So and so told them that 7.xx p-rod length would be ok and I installed my cam dot to dot! If you rule out these 2 issues I would look into your lifters as you may be collapsing them at high rpm. Seems unlikely but those are fairly agressive springs for a hydraulic roller cam.
Thanks for your concern.... but its not the lifters.
I didn't use cheap gm lifters...
I bought ones designed for high rpm and high spring pressures
I've put more money into my engine than some people have in their entire car(car price included)
The pushrods are not the wrong length....
Measured and have proper length and preload.

I sincerely believe the issue to be timing chain related...
I will find out when i get home off the road next week.

I've also now researched and have found several other people that have had a mis-marked chain...**** happens.... nobody has 100% quality control all the time

One engine builder has told me he has had chains from several manufacturers that were marked incorrectly...some only by a degree or two... one he got was 14* wrong...lol
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Old 01-13-2018, 01:39 AM   #34
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i know this is old thread but ur graph almost mimics my power loss after 6k.. did u ever figure out what was causing ur issue...Thanks
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Old 01-13-2018, 12:20 PM   #35
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i know this is old thread but ur graph almost mimics my power loss after 6k.. did u ever figure out what was causing ur issue...Thanks
You both have one thing in-common. You can see the common trait of it when engine starts to accelerate peak jumps up, then dips an starts to go higher.

In his case the problem is less sever allowing his engine's power to fall off at a slower rate than your's does.

To make power you have to have air intake velocity to pack cylinders, and exhaust air velocity out so the next intake charge will fill cylinder as close to max as possible. On the exhaust side you have things effecting engine's ability to get max cylinder fill, "Back Pressure caused by incorrect dia of exhaust pipe, muffler(s), sever bends that slow air flow as air doesn't like to bend either, flows best in straight pipe", an "Exhaust cylinder pulse Reversion Wave traveling pack up exhaust pipe slowing exhaust velocity air flow also".






Last edited by poorhousenext; 01-13-2018 at 12:28 PM.
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Old 01-13-2018, 08:13 PM   #36
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id still like to know what ended up causing his problem. Might lead me to look in the right direction..
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Old 01-17-2018, 01:07 AM   #37
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Quote:
Originally Posted by poorhousenext View Post
You both have one thing in-common. You can see the common trait of it when engine starts to accelerate peak jumps up, then dips an starts to go higher.

In his case the problem is less sever allowing his engine's power to fall off at a slower rate than your's does.

To make power you have to have air intake velocity to pack cylinders, and exhaust air velocity out so the next intake charge will fill cylinder as close to max as possible. On the exhaust side you have things effecting engine's ability to get max cylinder fill, "Back Pressure caused by incorrect dia of exhaust pipe, muffler(s), sever bends that slow air flow as air doesn't like to bend either, flows best in straight pipe", an "Exhaust cylinder pulse Reversion Wave traveling pack up exhaust pipe slowing exhaust velocity air flow also".





I caught that common denominator as well
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