C5R vs LS7
05-27-2008, 12:35 PM
#1
C5R vs LS7 Sorry to "re-ask" this but I could never find a CLEAR answer. On a 427+ CI engine, are the C5R heads (once ported) any better than the LS7 heads?
Based on what I COULD get form searching:
- the C5Rs come "as cast" vs the LS7s are already ported (so can not compare "stock to stock").
- the C5Rs have really small chambers (which would require either some major chamber work or a deep dish piston).
- the C5R heads will work with the LS7 intake (seems companies just drill the LS7 intake bolt pattern)
- exhaust flange design is the same
Based on what I COULD get form searching:
- the C5Rs come "as cast" vs the LS7s are already ported (so can not compare "stock to stock").
- the C5Rs have really small chambers (which would require either some major chamber work or a deep dish piston).
- the C5R heads will work with the LS7 intake (seems companies just drill the LS7 intake bolt pattern)
- exhaust flange design is the same
05-27-2008, 06:16 PM
#3
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C5R block info
https://ls1tech.com/forums/generation-iii-internal-engine/310618-c5r-block-info-vs-sleeved-blocks.html
Basic engine spec differences
http://www.corvetteracing.com/cars/c...ne_specs.shtml
The C5R heads have a taller deck and need a Kinsler manifold
http://www.sdparts.com/product/12480...numRacing.aspx
http://www.kinsler.com/page--GM--17.html
https://ls1tech.com/forums/generation-iii-internal-engine/310618-c5r-block-info-vs-sleeved-blocks.html
Basic engine spec differences
http://www.corvetteracing.com/cars/c...ne_specs.shtml
The C5R heads have a taller deck and need a Kinsler manifold
http://www.sdparts.com/product/12480...numRacing.aspx
http://www.kinsler.com/page--GM--17.html
05-28-2008, 06:30 AM
#6
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The C5R heads are designe for higher velocity air flow, not more volume as in the LS7 heads.
The C5r heads are for loads of torque. A properly build C5r block with the C5r heads can and does produce torque in the 630-650 lb ft range, but only 580-600 bhp with about a 6200 rpm red line.
Put on the LS7 heads and reverse those numbers and up the red line a bit.
Different heads for different results.
The C5r heads are for loads of torque. A properly build C5r block with the C5r heads can and does produce torque in the 630-650 lb ft range, but only 580-600 bhp with about a 6200 rpm red line.
Put on the LS7 heads and reverse those numbers and up the red line a bit.
Different heads for different results.
05-28-2008, 08:49 AM
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The C5R heads are designe for higher velocity air flow, not more volume as in the LS7 heads.
The C5r heads are for loads of torque. A properly build C5r block with the C5r heads can and does produce torque in the 630-650 lb ft range, but only 580-600 bhp with about a 6200 rpm red line.
Put on the LS7 heads and reverse those numbers and up the red line a bit.
Different heads for different results.
The C5r heads are for loads of torque. A properly build C5r block with the C5r heads can and does produce torque in the 630-650 lb ft range, but only 580-600 bhp with about a 6200 rpm red line.
Put on the LS7 heads and reverse those numbers and up the red line a bit.
Different heads for different results.
But those C5R engines are making those great numbers because they don't have the horrible air flow restrictions like we have we these plastic LS1/6/7 intakes. They have an intake that actually allows all or almost all of those cfm's the heads can flow to be used by the engine. Big difference.
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05-28-2008, 09:01 AM
#8
Sounds like the LS7 heads are much better for a street/strip car than.
But those C5R engines are making those great numbers because they don't have the horrible air flow restrictions like we have we these plastic LS1/6/7 intakes. They have an intake that actually allows all or almost all of those cfm's the heads can flow to be used by the engine. Big difference.
But those C5R engines are making those great numbers because they don't have the horrible air flow restrictions like we have we these plastic LS1/6/7 intakes. They have an intake that actually allows all or almost all of those cfm's the heads can flow to be used by the engine. Big difference.
FWIW any intake port on a cylinder head is going to "lose" flow when you put an intake manifold on it.
05-28-2008, 09:19 AM
#9
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Yeah, thats why I said "almost all". But clearly the plastic intakes we have essentially takes a badass 400cfm LS7 head and turns it into an L92 head, on any ci engine it sits on. Drop the C5R intake on it and you'll make 50+ RWHP.
05-28-2008, 11:11 AM
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Sounds like the LS7 heads are much better for a street/strip car than.
But those C5R engines are making those great numbers because they don't have the horrible air flow restrictions like we have we these plastic LS1/6/7 intakes. They have an intake that actually allows all or almost all of those cfm's the heads can flow to be used by the engine. Big difference.
But those C5R engines are making those great numbers because they don't have the horrible air flow restrictions like we have we these plastic LS1/6/7 intakes. They have an intake that actually allows all or almost all of those cfm's the heads can flow to be used by the engine. Big difference.
05-29-2008, 06:31 AM
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Street use an LS7 would be better. The C5r block is a road racing block. Guys have used them for drag racing, not sure if that is a good idea as the cylinder sleeves are quite long and does not like high rpms.
the World LSx block would be a better choice and is also made from the same aluminum as the C5R blocks
