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Old 03-02-2021, 06:38 PM   #15
cmitchell17

 
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Originally Posted by s346k View Post
the marks on top of the piston are not worrisome. the missing piece of the piston on the outside edge is why you need to replace it.

consider most setups using aftermarket, preassembled short blocks are making 2-3x more power than you are and have a plethora of variables ultimately leading to the engines demise.

it sounds like you need to replace that piston with another stock one and carry on. you might be able to get away with doing that in the car.
Yeah I understand and am with you, at least I need to look at it and to do that I basically have to pull the engine anyway and pull the piston out to get a look at it and may find unexpected damages anyway. It would seem like trying to get under there and figure out how you could torque back the rod bolts under the car seems like a nighmare haha.
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Old 03-02-2021, 06:42 PM   #16
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there are several pistons available for these engines. the question is: what is your goal with this engine? if you're staying na, i wouldn't bother with upgrading the pistons and rods. my rock stock long block has seen 7k+ for several months and a few thousand miles now, i wouldn't be afraid to upgrade the valve train and spin 7500.
Thanks, I am hearing a lot of different opinions on RPMs. Obviously I know the valve train being the weakest point for RPMS, but I am not sure if that is because it could be hitting a harmonic or something else.

With the damage I saw to my valve seats, I don't' see how I could completely rule out too high of rpms, I never road raced it or anything so when it did see high rpms they weren't sustained but it did happen pretty frequently and did see 7300+ before it could completely cut the fuel and decelerate.

My goal is to stay NA, I think FI is better suited for a truck LS application when you have more room for ICs and stuff. I am kind of torn between just not caring and trying to have a somewhat decent idle, it can be really annoying get shaken around at idle and is extremely annoying when you are at a rolling idle on the brake and the car is surging and lunging back and forth, and the worst part about having a bad idle is it makes your car look broken to clueless people who don't know anything about them. I was hoping there would be some analytical way of approaching trying to optimize idle and make all the power I can, but it looks like you just have to guess and check based on what someone else tells you. I like the idea of VVT but yes I understand it makes a negligible difference and is there mainly for its EGR effect, that doesn't mean I don't want to try to retain it and attempt to make use out of it. Yes I know with higher spring pressure than stock it becomes uncontrollable, I wish there was just some way we could fix that.

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Old 03-03-2021, 12:50 AM   #17
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my car saw a 10-15 whp loss when we started messing with the vvt (just to see what would happen). i don't think it would take much more camshaft to overcome the power loss. you must also consider low rpm and peak+ power delivery, ie power curve. on my car, the vvt really helped down low and past peak. the factory settings are optional for the stock camshaft, no doubt about that.

i'm in the same boat, which explains my interest. had a snafu that potentially compromised the #2 piston. ill find out more once i get the car out and about this year.

my plan now is increased compression with a very mild camshaft and an aftermarket cyl head. been looking at fed pretty hard. i spoke with them at pri a couple years ago and they are very knowledgeable, id trust their product. my money will be in the top end. id love to swap the piston with another stock one if it becomes a problem and then move on.

imho reliable 7k+ rpm requires, at minimum, a better than stock rocker (or maybe btr shaft setup if they release one for us) and a -better than- ls7 lifter. i have btr trunions to install. i'm hoping they'll limp me through this year. the car sees a lot of action in the warmer months, so i'm not completely convinced itll survive the year given what i did to it haha.
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Old 03-03-2021, 12:10 PM   #18
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Originally Posted by s346k View Post
my car saw a 10-15 whp loss when we started messing with the vvt (just to see what would happen). i don't think it would take much more camshaft to overcome the power loss. you must also consider low rpm and peak+ power delivery, ie power curve. on my car, the vvt really helped down low and past peak. the factory settings are optional for the stock camshaft, no doubt about that.

i'm in the same boat, which explains my interest. had a snafu that potentially compromised the #2 piston. ill find out more once i get the car out and about this year.

my plan now is increased compression with a very mild camshaft and an aftermarket cyl head. been looking at fed pretty hard. i spoke with them at pri a couple years ago and they are very knowledgeable, id trust their product. my money will be in the top end. id love to swap the piston with another stock one if it becomes a problem and then move on.

imho reliable 7k+ rpm requires, at minimum, a better than stock rocker (or maybe btr shaft setup if they release one for us) and a -better than- ls7 lifter. i have btr trunions to install. i'm hoping they'll limp me through this year. the car sees a lot of action in the warmer months, so i'm not completely convinced itll survive the year given what i did to it haha.
One of my only real interests in retaining some VVT movement is to see if it would help idle quality, I don't think it will but it would be nice to be able to test it to see.

I could see justifying the 3k+ amount in aftermarket heads, but only if it could get me more compression, for that amount of money I could buy new blocks and rotating assemblies.

So you think you "dropped" a valve seat?
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Old 03-03-2021, 12:38 PM   #19
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Originally Posted by cmitchell17 View Post
One of my only real interests in retaining some VVT movement is to see if it would help idle quality, I don't think it will but it would be nice to be able to test it to see.

I could see justifying the 3k+ amount in aftermarket heads, but only if it could get me more compression, for that amount of money I could buy new blocks and rotating assemblies.

So you think you "dropped" a valve seat?
I had to retune mine to get it to idle good, with the help of the tuning school and goat rope garage. It wouldn't idle at the rpm it was set to and would sometimes die when letting it return to idle while driving. It's a .640 lift cam, and idles rock solid now, low rpm driveability also got a lot better.
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Old 03-03-2021, 06:50 PM   #20
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I had to retune mine to get it to idle good, with the help of the tuning school and goat rope garage. It wouldn't idle at the rpm it was set to and would sometimes die when letting it return to idle while driving. It's a .640 lift cam, and idles rock solid now, low rpm driveability also got a lot better.
I left all my idle parameters 100% stock because non of that helped. I had to decrease virtual torque in the idle regions to get timing back up as it was pulling to much timing trying to keep it from over speeding at idle. I think it does help for stability with big cams if you let the throttle open more and let it dial back the timing and use more of the timing range for control rather than trying to let it barely crack the throttle to control speed at idle.

However, to adjust a lot of that you have to have a GEN III or GEN IV, we don't have access to a lot of the parameters we need on GEN V to control that kind of stuff, so you are left with what we have available in HP Tuners.

With the virtual torque adjustments, I was able to get back a reasonable timing value at idle (10-20 degrees, instead of negative timing almost) this helped the stability and sounded a lot better than the blattey and loud sound you get from not enough timing coming from the exhaust.

The only idle problem I have now is sometimes when you blip the throttle say when loaded up a hill and it revs to 1000 or so then let off sometimes it stumbles a little below idle speed. Again, I don't think we have the parameters we need to correct little drivability problems like this especially given the extra complexity of the GEN V stuff. Besides that I don't have any idle problems but then again my cam only had 4 degrees of overlap at .050.
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Old 03-03-2021, 06:51 PM   #21
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Does anyone have any experience running a .028 head gasket? This looks to be about my cheapest and only option to get more compression.
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Old 03-07-2021, 10:12 PM   #22
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I am thinking about a torque converter, since I am going to pull the motor and I should be able to just pull the old TC off and put a new one on while the motor is out.

I just feel like I would have to turn it more RPMs if I was to go with a bigger converter, so I could run a bigger cam?

I hate the idea of killing my driveability and I am scared the TC won't lock anymore in 2nd gear, and I've heard they won't lock until 4th or 5th with a higher stall at WOT and I want it locked 100% of the time at WOT? I think HP Tuners could have the ability to fix this and force any TC to lockup, but I think we just don't have the proper access to the certain tables we need to control lockup.
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Old 04-12-2021, 10:42 PM   #23
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So I want to bring this thread back up since my engine is out of my car and my heads are still with my machine shop and I don't know where to go next. There seems to be no info out there on valve seats.

So you can't buy stock replacement seats apparently, which makes it more difficult to size them. I have contacted CHE and other companies and haven't heard anything. The only thing I can find about upgraded valve seats are aftermarket castings that already have supposedly upgraded seats.

Also my exhaust seats looked fine but I'm not sure if I should try to upgrade them or not too.

So does anyone anywhere know of better seats to use or custom make some but with what material?

Its almost like you just basically have to buy aftermarket heads, I would definitely buy aftermarket castings if it would help get a smaller combustion chamber for more compression but that's apparently not the case with any of them as they just maintain the same chamber size.
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Old 04-12-2021, 11:17 PM   #24
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Originally Posted by s346k View Post

imho reliable 7k+ rpm requires, at minimum, a better than stock rocker (or maybe btr shaft setup if they release one for us) and a -better than- ls7 lifter. i have btr trunions to install. i'm hoping they'll limp me through this year. the car sees a lot of action in the warmer months, so i'm not completely convinced itll survive the year given what i did to it haha.

The factory rocker will last at 7K+ rpm with a trunnions upgrade like CHE. Brandon Hill run them, Brady ran them in his car, along with a lot of other guys/gals out there spinning their cars up above that. Once you going to an aftermarket rocker you’re adding more weight over the valve which isn’t the best thing. Also, Gwatney did a test with stock and aftermarket rockers. The factory rocker with a trunnion upgrade made more power and was more stable at higher rpm than the aftermarket stuff.
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Old 04-12-2021, 11:26 PM   #25
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Originally Posted by cmitchell17 View Post
So I want to bring this thread back up since my engine is out of my car and my heads are still with my machine shop and I don't know where to go next. There seems to be no info out there on valve seats.

So you can't buy stock replacement seats apparently, which makes it more difficult to size them. I have contacted CHE and other companies and haven't heard anything. The only thing I can find about upgraded valve seats are aftermarket castings that already have supposedly upgraded seats.

Also my exhaust seats looked fine but I'm not sure if I should try to upgrade them or not too.

So does anyone anywhere know of better seats to use or custom make some but with what material?

Its almost like you just basically have to buy aftermarket heads, I would definitely buy aftermarket castings if it would help get a smaller combustion chamber for more compression but that's apparently not the case with any of them as they just maintain the same chamber size.
You can get 14:1 out of the factory pistons and heads with flycutting, milling, and thinner gaskets.

A stock head milled .040 with .040 gaskets will get you around 13:1.

I personally am at 14:1 with a thinner gasket, milled CID small chamber heads, and flycut pistons
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Old 04-13-2021, 06:25 PM   #26
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The factory rocker will last at 7K+ rpm with a trunnions upgrade like CHE. Brandon Hill run them, Brady ran them in his car, along with a lot of other guys/gals out there spinning their cars up above that. Once you going to an aftermarket rocker you’re adding more weight over the valve which isn’t the best thing. Also, Gwatney did a test with stock and aftermarket rockers. The factory rocker with a trunnion upgrade made more power and was more stable at higher rpm than the aftermarket stuff.
i have been following those guys. i have upgraded trunnions. the only thing i'm not sold on is durability. those are racecars. naturally they're going to want every last hp and ounce of weight off the valve train. i put 12k+ miles a year on my car. not a dd, no winter driving. i often find myself 800-1k miles from home. i also know the factory style rockers are proven to deflect. is it enough to merit concern? idk. id still be leery of putting a stock style rocker on a 7500 rpm street car that never has the valve covers off and is getting driven all over hells half acre. i think that shaft mount setup will be great for them and certainly would be beneficial.
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Old 04-13-2021, 09:30 PM   #27
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Originally Posted by 17camaroSS View Post
You can get 14:1 out of the factory pistons and heads with flycutting, milling, and thinner gaskets.

A stock head milled .040 with .040 gaskets will get you around 13:1.

I personally am at 14:1 with a thinner gasket, milled CID small chamber heads, and flycut pistons
Thanks, I calculated I should be at 12.95:1 with a .015 head mill, and a .028 gasket but maybe im using bad numbers:
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Im using piston to deck height at TDC that I measured with calipers at .013, and 59.02CC stock chamber size and figuring 3.3 CCs off the stock chamber by milling .015 but not sure if thats accurate, and using normal head gasket bore size with .028 compressed height (Cometic Gasket).
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Old 04-13-2021, 10:49 PM   #28
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i have been following those guys. i have upgraded trunnions. the only thing i'm not sold on is durability. those are racecars. naturally they're going to want every last hp and ounce of weight off the valve train. i put 12k+ miles a year on my car. not a dd, no winter driving. i often find myself 800-1k miles from home. i also know the factory style rockers are proven to deflect. is it enough to merit concern? idk. id still be leery of putting a stock style rocker on a 7500 rpm street car that never has the valve covers off and is getting driven all over hells half acre. i think that shaft mount setup will be great for them and certainly would be beneficial.
I get what you’re saying for sure, but Brandon drives his car all over as do I and I even drove my Trans Am for 3 years daily with a trunnion upgrade and spun it to 7300-7400 every other weekend. I personally wouldn’t hesitate at all to do run the factory rocker with a setup like that. Lots of guys do it with their streetcars. Just something to look at IMO
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