Building a stock bottom end LS7
Building a stock bottom end LS7 Hello all, been collecting parts for my LS build and have some questions now that I have a solid direction. I'm starting with a core LS7 block and rotating assembly, with plans to use the stock bottom end unmodified, essentially. I'm looking at the induction side and was looking for advice. So far, here are some ideas:
-Mild came in the 22x/22x range, unsure on lift/duration. Looking for good idle/street manners
-LS7 heads w/ new valve guides, OEM valves, single springs to .650 lift, light milling of heads.
It seems milling only vice mill/port job is the most economical for hp/$, any insight into this?
-Intake manifold, I'm between a ported Stock LS7 intake or Ported Fast 102 with matching TB port on either. I am thinking on a mild build, the ported Fast may be wasted money.
-Will the factory ZO6 air intake/plenum be sufficient, or is there much to gain replacing that piece?
-Anyone seen the difference between 1.75 vs 1.85 primaries on headers, all else being equal? Will I be giving up power with the smaller tubing?
All of that should give me more than enough power on this engine, I'm interested in keeping the TI rods and stock valvetrain for lightness. The idea is for a roadcourse friendly engine behind an MM6 t56 and 3.43 or 3.27 gearing.
-Mild came in the 22x/22x range, unsure on lift/duration. Looking for good idle/street manners
-LS7 heads w/ new valve guides, OEM valves, single springs to .650 lift, light milling of heads.
It seems milling only vice mill/port job is the most economical for hp/$, any insight into this?
-Intake manifold, I'm between a ported Stock LS7 intake or Ported Fast 102 with matching TB port on either. I am thinking on a mild build, the ported Fast may be wasted money.
-Will the factory ZO6 air intake/plenum be sufficient, or is there much to gain replacing that piece?
-Anyone seen the difference between 1.75 vs 1.85 primaries on headers, all else being equal? Will I be giving up power with the smaller tubing?
All of that should give me more than enough power on this engine, I'm interested in keeping the TI rods and stock valvetrain for lightness. The idea is for a roadcourse friendly engine behind an MM6 t56 and 3.43 or 3.27 gearing.
Hello all, been collecting parts for my LS build and have some questions now that I have a solid direction. I'm starting with a core LS7 block and rotating assembly, with plans to use the stock bottom end unmodified, essentially. I'm looking at the induction side and was looking for advice. So far, here are some ideas:
-Mild came in the 22x/22x range, unsure on lift/duration. Looking for good idle/street manners
-LS7 heads w/ new valve guides, OEM valves, single springs to .650 lift, light milling of heads.
It seems milling only vice mill/port job is the most economical for hp/$, any insight into this?
-Intake manifold, I'm between a ported Stock LS7 intake or Ported Fast 102 with matching TB port on either. I am thinking on a mild build, the ported Fast may be wasted money.
-Will the factory ZO6 air intake/plenum be sufficient, or is there much to gain replacing that piece?
-Anyone seen the difference between 1.75 vs 1.85 primaries on headers, all else being equal? Will I be giving up power with the smaller tubing?
All of that should give me more than enough power on this engine, I'm interested in keeping the TI rods and stock valvetrain for lightness. The idea is for a roadcourse friendly engine behind an MM6 t56 and 3.43 or 3.27 gearing.
-Mild came in the 22x/22x range, unsure on lift/duration. Looking for good idle/street manners
-LS7 heads w/ new valve guides, OEM valves, single springs to .650 lift, light milling of heads.
It seems milling only vice mill/port job is the most economical for hp/$, any insight into this?
-Intake manifold, I'm between a ported Stock LS7 intake or Ported Fast 102 with matching TB port on either. I am thinking on a mild build, the ported Fast may be wasted money.
-Will the factory ZO6 air intake/plenum be sufficient, or is there much to gain replacing that piece?
-Anyone seen the difference between 1.75 vs 1.85 primaries on headers, all else being equal? Will I be giving up power with the smaller tubing?
All of that should give me more than enough power on this engine, I'm interested in keeping the TI rods and stock valvetrain for lightness. The idea is for a roadcourse friendly engine behind an MM6 t56 and 3.43 or 3.27 gearing.
You can make more power porting the heads if someone good ports them. They are really good straight from GM, except for the issue with the exhaust valves dropping. Usually, new guides and solid stem exhaust valves fix the problem, so I'd say you're on the right track. A trunion upgrade for the rocker arms may not be a bad investment either.
I would shoot for more exhaust duration on the cam. You can go bigger on the intake duration too with a healthy amount of overlap and still have good street manners, but it's going to be heavily influenced by the guy tuning the ECM. I've driven around in a LS7 ZO6 with a 23x/25x cam and would cruise along just fine under 1000RPM without any crazy surge or bucking.
You can make more power porting the heads if someone good ports them. They are really good straight from GM, except for the issue with the exhaust valves dropping. Usually, new guides and solid stem exhaust valves fix the problem, so I'd say you're on the right track. A trunion upgrade for the rocker arms may not be a bad investment either.
You can make more power porting the heads if someone good ports them. They are really good straight from GM, except for the issue with the exhaust valves dropping. Usually, new guides and solid stem exhaust valves fix the problem, so I'd say you're on the right track. A trunion upgrade for the rocker arms may not be a bad investment either.
Thanks for info on the cams, this makes sense as I was drawing too much of my information from the smaller 6.0/6.2l motors, with smaller ports on the heads. Just haven't seen a lot on LS7 cams like what I'm doing. The +.600 lift stuff is a turn off to me with routine valve spring replacement, breakage, and excessive maintenance, basically, in addition to the added valvetrain weight.
Tony Mamo was kind enough to offer his opinion on the heads and intake, and he felt the ported Fast 102 and Ported heads is worth the extra effort, and if you think about it, you can gain power here without stressing components as much compared to N2O or bigger cams. I think I will look into going this route if I do end up with the Fast intake.
1 7/8 headers are going to be a tight squeeze, but I think we can get them in. They offer a nice set of long tubes for my configuration. Not a pleasant install, though.
Was this the Halltech piece you were referring to? SCP halltech intake
Last edited by msmnick; Jun 6, 2014 at 04:22 PM.
TECH Junkie
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You need to step up to at least a cam in the mid 230's and probably mid 240's on the exhaust. It will idle just fine with those cubes. Plenty of custom cam people out there to get quotes from.
I don't know how big the exhaust port is on the LS7 head but on an LS3 head it is 1.625". That is the reason I went with a 1 3/4" x 1 7/8" stepped header. Something to consider if your exhaust port is the same size and if it helps with any with the needed room. So like a nice project you have.
I don't know how big the exhaust port is on the LS7 head but on an LS3 head it is 1.625". That is the reason I went with a 1 3/4" x 1 7/8" stepped header. Something to consider if your exhaust port is the same size and if it helps with any with the needed room. So like a nice project you have.
You need to step up to at least a cam in the mid 230's and probably mid 240's on the exhaust. It will idle just fine with those cubes. Plenty of custom cam people out there to get quotes from.
I don't know how big the exhaust port is on the LS7 head but on an LS3 head it is 1.625". That is the reason I went with a 1 3/4" x 1 7/8" stepped header. Something to consider if your exhaust port is the same size and if it helps with any with the needed room. Sounds like a nice project you have.
I don't know how big the exhaust port is on the LS7 head but on an LS3 head it is 1.625". That is the reason I went with a 1 3/4" x 1 7/8" stepped header. Something to consider if your exhaust port is the same size and if it helps with any with the needed room. Sounds like a nice project you have.
-LS7 block, Darton wet sleeved block
Block had one bad sleeve, originally was going to do one, then was going to do ERL superdeck, decided on wet sleeves for strength/economical balance
- LS7 Stock Rods, Stock pistons, Stock crank
Using the stock titanium rods due to weight. The Titanium rods vs H-beam
aftermarket steel rods saves you 3.3lbs (4xx grams vs 6xx grams for one
popular aftermarket rod)
-Stock LS7 heads to Air-Flow Research for cnc and hand porting
Tony Mamo will be handling the port work. He will also handle the cam
cam selection, spring selection, and assembly. This will be Stock TI intake
valves, aftermarket solid stem exhaust valves, and PAC spring/retainer kit.
-FAST102mm Intake for LS7
To be ported by AFR.
-Morrel lifters, Comp Cams Trunion kit, Comp cams push rods
Lifters and trunion kit for reliability mods mostly. On the shelf. Pushrods
to be spec'd on assembly.
-Tentative engine items:
-E67 ECM/Pedal/Wiring harness
-Scoggin-dickey LS7 wetsump conversion spacer
-LS3 style oil pump/pickup/timing set
-Halltech Superbee Intake
-Sensors and everything else from Donor 5.3
-LS9 valve covers/coils
-LSx corvette front drive accessories
-Turn-one steering pump
-LS2/3 ATI damper
-1 7/8 Primary long tube headers
Anyone have suggestions or tricks to add? I think even if its not perfect, it will be a winning combination. I left out the timing/wet sump conversion stuff and other parts that I'll need.
Block had one bad sleeve, originally was going to do one, then was going to do ERL superdeck, decided on wet sleeves for strength/economical balance
- LS7 Stock Rods, Stock pistons, Stock crank
Using the stock titanium rods due to weight. The Titanium rods vs H-beam
aftermarket steel rods saves you 3.3lbs (4xx grams vs 6xx grams for one
popular aftermarket rod)
-Stock LS7 heads to Air-Flow Research for cnc and hand porting
Tony Mamo will be handling the port work. He will also handle the cam
cam selection, spring selection, and assembly. This will be Stock TI intake
valves, aftermarket solid stem exhaust valves, and PAC spring/retainer kit.
-FAST102mm Intake for LS7
To be ported by AFR.
-Morrel lifters, Comp Cams Trunion kit, Comp cams push rods
Lifters and trunion kit for reliability mods mostly. On the shelf. Pushrods
to be spec'd on assembly.
-Tentative engine items:
-E67 ECM/Pedal/Wiring harness
-Scoggin-dickey LS7 wetsump conversion spacer
-LS3 style oil pump/pickup/timing set
-Halltech Superbee Intake
-Sensors and everything else from Donor 5.3
-LS9 valve covers/coils
-LSx corvette front drive accessories
-Turn-one steering pump
-LS2/3 ATI damper
-1 7/8 Primary long tube headers
Anyone have suggestions or tricks to add? I think even if its not perfect, it will be a winning combination. I left out the timing/wet sump conversion stuff and other parts that I'll need.
