Spun bearing turned stroker build
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Teching In
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Spun bearing turned stroker build Sorry in advance guys, may come off as a newb to some of thee LS overlords, my first time building an engine. So I've got my engine torn down and I'm ready to order some parts and get some machine work done. I have an LS2 aluminum block that I want to turn into a 402 (stroker crank, pistons, rods, bearings, the whole balanced rotating assembly). I see kits available from damn near everybody but they all have different compression ratios for whatever size may be (65) combustion chamber. Throw the cam in the equation and I'm just getting lost in space as far as numbers and ratios go. My pop's is telling me a .600 lift cam is too high for the street but that's about all I see on Texas speeds web sight. My plan was to use the ls2 heads and change out the springs but will those heads even work with the longer throw crank and when searching cams do I search for stroker cams or just regular ls2 cams? I'm kind of confused if you have not noticed.
The engines going in a Trailblazer SS that's street driven. Was leaning on the Summit racing 402 stroker kit as it was the one closest to the compression ratio the engine had. (stock 10.9:1, summit 11:1, both at 65mm combustion chamber) Was going to pair that with the TSP 233/239 .600"/.600" 112 LSA Camshaft as it states having no piston to valve clearance issues but like I was saying pops says that's too much for the street in his opinion. Next thing is I have cathedral port heads so do I need to stick to a strictly cathedral cam? The questions go on, again sorry guys. Maybe one of you pros that have stroked out your LS can point me down the right path.
The engines going in a Trailblazer SS that's street driven. Was leaning on the Summit racing 402 stroker kit as it was the one closest to the compression ratio the engine had. (stock 10.9:1, summit 11:1, both at 65mm combustion chamber) Was going to pair that with the TSP 233/239 .600"/.600" 112 LSA Camshaft as it states having no piston to valve clearance issues but like I was saying pops says that's too much for the street in his opinion. Next thing is I have cathedral port heads so do I need to stick to a strictly cathedral cam? The questions go on, again sorry guys. Maybe one of you pros that have stroked out your LS can point me down the right path.
Sorry in advance guys, may come off as a newb to some of thee LS overlords, my first time building an engine. So I've got my engine torn down and I'm ready to order some parts and get some machine work done. I have an LS2 aluminum block that I want to turn into a 402 (stroker crank, pistons, rods, bearings, the whole balanced rotating assembly). I see kits available from damn near everybody but they all have different compression ratios for whatever size may be (65) combustion chamber. Throw the cam in the equation and I'm just getting lost in space as far as numbers and ratios go. My pop's is telling me a .600 lift cam is too high for the street but that's about all I see on Texas speeds web sight. My plan was to use the ls2 heads and change out the springs but will those heads even work with the longer throw crank and when searching cams do I search for stroker cams or just regular ls2 cams? I'm kind of confused if you have not noticed.
The engines going in a Trailblazer SS that's street driven. Was leaning on the Summit racing 402 stroker kit as it was the one closest to the compression ratio the engine had. (stock 10.9:1, summit 11:1, both at 65mm combustion chamber) Was going to pair that with the TSP 233/239 .600"/.600" 112 LSA Camshaft as it states having no piston to valve clearance issues but like I was saying pops says that's too much for the street in his opinion. Next thing is I have cathedral port heads so do I need to stick to a strictly cathedral cam? The questions go on, again sorry guys. Maybe one of you pros that have stroked out your LS can point me down the right path.
The engines going in a Trailblazer SS that's street driven. Was leaning on the Summit racing 402 stroker kit as it was the one closest to the compression ratio the engine had. (stock 10.9:1, summit 11:1, both at 65mm combustion chamber) Was going to pair that with the TSP 233/239 .600"/.600" 112 LSA Camshaft as it states having no piston to valve clearance issues but like I was saying pops says that's too much for the street in his opinion. Next thing is I have cathedral port heads so do I need to stick to a strictly cathedral cam? The questions go on, again sorry guys. Maybe one of you pros that have stroked out your LS can point me down the right path.
Sit down with your machinist and have a conversation about what you want from this build. Dont exaggerate and don’t leave out any details with him. He should be able to give you sound advice and get you on the right path for your rotating assembly, cylinder head work, and even camshaft choice. Trust your builder. I cannot stress that enough. You’ll get 10 opinions here on what works best, and nothing will aggravate your machinist more than you telling him what you read on the internet.
Being this motor spun a bearing, I assume it is an AWD model. If you are not tied to the AWD, I would look heavily into doing a RWD conversion with an LS2/LS3 oil pan to get a rear sump. The front sump is the main cause of bearing issues in those SUVs. @84ta406 can help you out with some solid opinions as he has a pretty nice setup in his.
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Teching In
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Being this motor spun a bearing, I assume it is an AWD model. If you are not tied to the AWD, I would look heavily into doing a RWD conversion with an LS2/LS3 oil pan to get a rear sump. The front sump is the main cause of bearing issues in those SUVs. @84ta406 can help you out with some solid opinions as he has a pretty nice setup in his.
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@CuttaCal,
@Che70velle is 100% right. Before you order anything, sit down with the machinist or builder and be honest about your goals, budget, converter, gears, fuel, and how you want it to drive. That will keep you from buying parts that don't match, and it keeps your machinist from having to undo internet decisions.
On the cam side, .600 lift by itself isn't too much for a street LS. What makes one feel street-friendly or not is duration and valve events, not lift alone. Your LS2 cathedral heads will work fine on a 402, and you do not need some special “stroker cam” or “cathedral cam”. You pick the cam for the combo and the powerband you want, then verify piston to valve clearance with your exact parts and machine work.
If you are leaning towards one of our Pro LS 402 rotating kits to stay close to your compression target, that is a reasonable starting point. Just don't lock it in until your machinist confirms the final bore and deck, and you have real chamber volume numbers for your heads.
Also, confirm what year TBSS you have so the crank reluctor matches what the ECM expects. 2006 is typically 24x, while 2007 to 2009 is typically 58x, and that can steer you toward the right crank and front cover parts.
Once you have those details nailed down, the cam choice gets simpler, and you avoid surprises.
@Che70velle is 100% right. Before you order anything, sit down with the machinist or builder and be honest about your goals, budget, converter, gears, fuel, and how you want it to drive. That will keep you from buying parts that don't match, and it keeps your machinist from having to undo internet decisions.
On the cam side, .600 lift by itself isn't too much for a street LS. What makes one feel street-friendly or not is duration and valve events, not lift alone. Your LS2 cathedral heads will work fine on a 402, and you do not need some special “stroker cam” or “cathedral cam”. You pick the cam for the combo and the powerband you want, then verify piston to valve clearance with your exact parts and machine work.
If you are leaning towards one of our Pro LS 402 rotating kits to stay close to your compression target, that is a reasonable starting point. Just don't lock it in until your machinist confirms the final bore and deck, and you have real chamber volume numbers for your heads.
Also, confirm what year TBSS you have so the crank reluctor matches what the ECM expects. 2006 is typically 24x, while 2007 to 2009 is typically 58x, and that can steer you toward the right crank and front cover parts.
Once you have those details nailed down, the cam choice gets simpler, and you avoid surprises.
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Be aware the LS2 block has very short cylinder sleeves (I think 5.45 inches) and a long stroke can be an issue if you do not order the correct pistons. This is where the machinist can come into play and get you the right pistons is you go with a 4-inch stroke. I think many of them like to keep it and a stroke of 3.8-3.9 inches and under for an LS2 block.
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Verdad Gallardo All good advice. For long term reliability, a 3.875 stroke isn’t a bad idea. With a 4.00" bore and 3.875" stroke, you end up at 390 cubes. This is only 1.5 cubes/cylinder less than the 402, and I don't think you'd ever notice the difference power wise.....
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From: Mefis
True, but who makes an affordable 3.875 crank? You could do a K1 or Compstar 3.9 crank. Or an L8T crank at 3.858 with 6.2 in rods and shelf 1.115 CH pistons and be .004 out of the hole. But then you'd probably need Mallory to balance it, a 8 bolt flex plate and a modified crank gear to accommodate the radius on the snout.
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Joined: Jun 2016
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From: Central Cal.
Actually a .025" difference, but who's counting??
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,615
From: Central Cal.
