High compression & Oem stock block

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Jan 6, 2020 | 12:52 PM
  #1  
Working on my personal build. Thinking about a dry sump high rpm 377ci. I know it's an odd question but anyone know if these GM blocks (LS3/L92) can hold 14+ compression or will it require sleeves?
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Jan 6, 2020 | 01:31 PM
  #2  
Quote: Working on my personal build. Thinking about a dry sump high rpm 377ci. I know it's an odd question but anyone know if these GM blocks (LS3/L92) can hold 14+ compression or will it require sleeves?
I know of a few who went 13.8-14.0 on their sbe LS7's while running E85, but anything higher than that I would think a sleeve would be prudent.
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Jan 6, 2020 | 01:56 PM
  #3  
NA compression is nothing compared to boost pressures being run in forced induction applications. I wouldn’t think you’d have a problem.

You’ll make at most like 600 ft lb out of a 377.
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Jan 6, 2020 | 03:12 PM
  #4  
Nice! Good to know for sure. I was thinking of resleeving or going to the LS9 block. I know I can do a 416 but this is more of a personal challenge to push a 377ci pretty far N/A max rpms 8500ish lol
In the brain storming process now.
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Jan 6, 2020 | 03:54 PM
  #5  
Quote: NA compression is nothing compared to boost pressures being run in forced induction applications. I wouldn’t think you’d have a problem.

You’ll make at most like 600 ft lb out of a 377.
Yep, It's not a matter of compression, It how much cylinder pressure any given combination will produce N.A or boosted during the combustion process.
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Jan 6, 2020 | 06:11 PM
  #6  
Quote: Nice! Good to know for sure. I was thinking of resleeving or going to the LS9 block. I know I can do a 416 but this is more of a personal challenge to push a 377ci pretty far N/A max rpms 8500ish lol
In the brain storming process now.
I would be more concerned with how you're going to oil it at 8500

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Jan 6, 2020 | 08:59 PM
  #7  
Quote: I would be more concerned with how you're going to oil it at 8500
Aivid external oil pump setup. I'm certain I misspelled it.
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Jan 7, 2020 | 07:49 AM
  #8  
Quote: Yep, It's not a matter of compression, It how much cylinder pressure any given combination will produce N.A or boosted during the combustion process.
^This. Similar topic was just discussed regarding boost. Only thing that matters is cylinder pressure.
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Jan 7, 2020 | 08:27 AM
  #9  
As ER asked oiling ....you gotten past that. You can do a resleeved block in which case you may as well get a larger Piston. Which would put more HP on the plate. Or do the economical thing and just hard block it. If it isn't no Cubic inch rules why would someone resleeved and stick to the as is bore size? $2000 + Vs hard block? The cylinders move around with Hi RPM and compression...Story from ER yrs ago on the Stock cubed 8800 rpm Ls3.
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Jan 7, 2020 | 08:36 AM
  #10  
Quote: As ER asked oiling ....you gotten past that. You can do a resleeved block in which case you may as well get a larger Piston. Which would put more HP on the plate. Or do the economical thing and just hard block it. If it isn't no Cubic inch rules why would someone resleeved and stick to the as is bore size? $2000 + Vs hard block? The cylinders move around with Hi RPM and compression...Story from ER yrs ago on the Stock cubed 8800 rpm Ls3.
It's more of a personal challenge for myself, I want to stay stock cubic inch (376ci)
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Jan 7, 2020 | 11:12 AM
  #11  
Brother Y would you spend the 2000.oo plus just to retain the stock cylinder size? Or just add a few bucks for a better block. I understand wanting to stay @ a certain cubic inch limit. Just don't see the need or want to resleeve a block unless doing a larger bore and or a larger engine - Sleeve for a FI application. I get the point of retaining the cubic inch size.. If u like it I luv it.... A fill kills the problem with cylinder movement also heard a few good things about block fill and DR track applications. Not so great for the street.... Keeping the oil cool with a larger oil cooler is key ...
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Jan 7, 2020 | 11:27 AM
  #12  
I get your thought...
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Jan 7, 2020 | 11:53 AM
  #13  
A member of the CF forums (RobZ) ran a de-stroked LS7, 388 ci , in his Vette.........9K RPM if I remember correctly.
That motor was up for sale for a while, but it might give an insight on what he did on his build

https://www.corvetteforum.com/forums...-upgrades.html
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Jan 7, 2020 | 12:42 PM
  #14  
Quote: A member of the CF forums (RobZ) ran a de-stroked LS7, 388 ci , in his Vette.........9K RPM if I remember correctly.
That motor was up for sale for a while, but it might give an insight on what he did on his build

https://www.corvetteforum.com/forums...-upgrades.html
Bighammer here also runs a 388 turns it 8600+. 62 if I ever build my bottom end, it will be 13:1 (or as close as i can get it) for street duty on e85. With your heavy car I would seriously consider more stroke and less RPM (8000) just to give it that punch in the gut feeling when you nail it
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Jan 7, 2020 | 01:33 PM
  #15  
Quote: Bighammer here also runs a 388 turns it 8600+. 62 if I ever build my bottom end, it will be 13:1 (or as close as i can get it) for street duty on e85. With your heavy car I would seriously consider more stroke and less RPM (8000) just to give it that punch in the gut feeling when you nail it
I'm shooting for 3000lb race weight, I'll never see the streets with this build really but I might have to do some more homework as I do wish to turn 8k+
Goal is to hit 8.60s or better 1/4 ETs on raw power. I like what the SBE guys are doing but I will not invest good stuff while running stock rods and pistons etc I know it is a tall order but I like to party.
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Jan 7, 2020 | 01:34 PM
  #16  
Quote: Brother Y would you spend the 2000.oo plus just to retain the stock cylinder size? Or just add a few bucks for a better block. I understand wanting to stay @ a certain cubic inch limit. Just don't see the need or want to resleeve a block unless doing a larger bore and or a larger engine - Sleeve for a FI application. I get the point of retaining the cubic inch size.. If u like it I luv it.... A fill kills the problem with cylinder movement also heard a few good things about block fill and DR track applications. Not so great for the street.... Keeping the oil cool with a larger oil cooler is key ...
I'd like to stay stock LS3 block vs aftermarket or sleeving it. I was thinking of even doing a 416 maybe 83-8500rpms max and half fill the block. I'm just looking for A to B 1/4 mile passes.
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Jan 7, 2020 | 01:58 PM
  #17  
I have a very similar build on the stand now. I also used an Aviaid external oil pump. I had a lot of issues with a melting pump and not loosing pressure throughout the run. I data log, Racepak, oil pressure and can clearly see what starts as 80lbs at launch drops to just over 40 by the lights. I made the switch to Dart only because I had trouble keeping the bores round. 13.75-1 compression and 28 degrees timing. This was with a LS3 block and 416ci. 7700rpm shifts and almost 7600 lights.
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Jan 7, 2020 | 02:53 PM
  #18  
Quote: I have a very similar build on the stand now. I also used an Aviaid external oil pump. I had a lot of issues with a melting pump and not loosing pressure throughout the run. I data log, Racepak, oil pressure and can clearly see what starts as 80lbs at launch drops to just over 40 by the lights. I made the switch to Dart only because I had trouble keeping the bores round. 13.75-1 compression and 28 degrees timing. This was with a LS3 block and 416ci. 7700rpm shifts and almost 7600 lights.
Nice! I really wanted to stay with a stock block but have been told the bores will shift within time. Thank you for your input, that really helps me pick what block.
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Jan 7, 2020 | 03:06 PM
  #19  
Quote: Nice! I really wanted to stay with a stock block but have been told the bores will shift within time. Thank you for your input, that really helps me pick what block.
Not an issue if you hardblok it. Fill it at least 3/4 of the way up.
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Jan 7, 2020 | 03:12 PM
  #20  
Quote: Not an issue if you hardblok it. Fill it at least 3/4 of the way up.
Good to know, I've never had that done but can any water be ran through that being 3/4 filled?
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