WCCH Small Bore LS7 heads
You can fit an LS7 head on an LS3 block. I believe CSP did that. I think the final bore was either a 4.090 or 4.100.
Also as I said earlier the small/medium bore from Mast were discontinued because of lacking demand and they did such a great job witht he LS3 heads.
Also as I said earlier the small/medium bore from Mast were discontinued because of lacking demand and they did such a great job witht he LS3 heads.
TECH Addict
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From: Battlecreek, MI / Mansfield, OH
True. After doing some reading, I saw 4.100 is safe to run LS7 heads on. But I wouldn't feel comfortable going 4.100 on an LS3 even with a sonic checking though.
Staging Lane
Joined: May 2010
Posts: 63
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I wish people would get off the flow numbers soap box. All this tells me is the max amount of air that can run through the intake runner at each lift. It's the aerodynamics of the port, meaning how fast your intake manifold and cylinder head intake runner working together can fill your cylinders with fuel and air. That's why port velocity is more important. There's a cylinder head article I read within the past year talking about port shapes, CFM, and port velocity. One cylinder head designer showed an example of two BBC heads flowing the same amount of CFM, but one made a 150hp more then the other. Why is that? because of a better port design and a flatter valve angle which equated to a higher port velocity. This also applies to an intake manifold. Someone was using a GM performance parts intake manifold and ported it to keep up with his 400CFM heads then switched over to Carys two piece intake and picked up over 30Hp if I remember right. Why is that, a better port design and more velocity. Also it makes no since to me putting a set of high flowing heads on a motor with out the intake manifold to match the heads. A very popular cylinder company put the L92 victor jr. on a set of heads that flowed 360 CFM while they were on a flow bench and they dropped to around 318 CFM. Food for thought.
Last edited by dwill73; Feb 24, 2011 at 07:34 PM.
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I noticed the new Trick Flow LS7 and LS3 heads are exactly the same flow numbers and 12deg valve angles, so the LS3 head is like having a small bore LS7 head...Should be interesting heads especially if they offer some larger CC runner options..
L92/LS3
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
LS7
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4.125" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
L92/LS3
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
LS7
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4.125" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
Staging Lane
Joined: May 2010
Posts: 63
Likes: 0
I noticed the new Trick Flow LS7 and LS3 heads are exactly the same flow numbers and 12deg valve angles, so the LS3 head is like having a small bore LS7 head...Should be interesting heads especially if they offer some larger CC runner options..
L92/LS3
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
LS7
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4.125" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
L92/LS3
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
LS7
255 cc
2.100 intake valve
69cc chambers
1.300 dual spring
4.125" minimum bore
Flow Numbers
Lift Intake Exhaust
.100 72 62
.200 159 117
.300 234 179
.400 292 224
.500 333 240
.600 357 252
Staging Lane
Joined: May 2010
Posts: 63
Likes: 0
Staging Lane
Joined: May 2010
Posts: 63
Likes: 0
I understand that completely. Like port velocity and port shape is way more important then raw flow numbers, which some folks don't comprehend. Maybe someday I'll get a chance to flow my head with the intake on for the hell of it.
TECH Apprentice
Joined: Jun 2007
Posts: 364
Likes: 0
I wish people would get off the flow numbers soap box. All this tells me is the max amount of air that can run through the intake runner at each lift. It's the aerodynamics of the port, meaning how fast your intake manifold and cylinder head intake runner working together can fill your cylinders with fuel and air. That's why port velocity is more important. There's a cylinder head article I read within the past year talking about port shapes, CFM, and port velocity. One cylinder head designer showed an example of two BBC heads flowing the same amount of CFM, but one made a 150hp more then the other. Why is that? because of a better port design and a flatter valve angle which equated to a higher port velocity. This also applies to an intake manifold. Someone was using a GM performance parts intake manifold and ported it to keep up with his 400CFM heads then switched over to Carys two piece intake and picked up over 30Hp if I remember right. Why is that, a better port design and more velocity. Also it makes no since to me putting a set of high flowing heads on a motor with out the intake manifold to match the heads. A very popular cylinder company put the L92 victor jr. on a set of heads that flowed 360 CFM while they were on a flow bench and they dropped to around 318 CFM. Food for thought.
On a 535 a set of canted valve heads were used with advertised flow of 370-ish. The car would not go any quicker than 10 teens to 20's.
A set of 350 cfm heads were bolted on, car went 9.90's or better off the trailer. The 350 cfm had better velocities so the combo recovered quicker after shifts.
This is a 3450 race weight.
Last time I was at Virginia Speed, Shawn had a few sets of the PI LS7 heads in stock, both medium and large bore versions. It is one of his most popular heads that he uses. I had a set of the 4.0 bore ETP LS7 heads, and they are works of art. The new MAST stuff is LS3.
Staging Lane
Joined: May 2010
Posts: 63
Likes: 0
The Ls7 4.0 heads are perfect for someone that wants to stick with a 6.0 iron block and still make respectable power. For what you pay for some aftermarket blocks I can build a whole new short block.
Staging Lane
Joined: May 2010
Posts: 63
Likes: 0
This is true. I've migrated from the Pontiac world.
On a 535 a set of canted valve heads were used with advertised flow of 370-ish. The car would not go any quicker than 10 teens to 20's.
A set of 350 cfm heads were bolted on, car went 9.90's or better off the trailer. The 350 cfm had better velocities so the combo recovered quicker after shifts.
This is a 3450 race weight.
On a 535 a set of canted valve heads were used with advertised flow of 370-ish. The car would not go any quicker than 10 teens to 20's.
A set of 350 cfm heads were bolted on, car went 9.90's or better off the trailer. The 350 cfm had better velocities so the combo recovered quicker after shifts.
This is a 3450 race weight.