Heads.... Patriot vs. Trickflow
Registered User
Joined: Apr 2007
Posts: 549
From: Lancaster, Texas
alright, i dont retain numbers very long, and i know that this has been discussed a million times on here.....BUT if you are using a 58cc head, that is the same as stock, so you wont need to get anything back with a thinner gasket.
i believe the lt4 head is 54 or 54.4cc and ups the cr to around 11
as mentioned above, the new trickflow head will raise compression.
i believe the lt4 head is 54 or 54.4cc and ups the cr to around 11
as mentioned above, the new trickflow head will raise compression.
LT4 = 10.8 CR
LT1 = 170cc Intake Port Volume
LT4 = 195 Intake Port Volume
Combustion Chamber size 54.4 cc both
Increase in CR on LT4 due to different pistons which have shallower valve pockets.
Different head gaskets are used on LT4 due to higher CR
58cc chambers will lower CR on both engines; thinner gaskets gets it back. Guess why TrickFlow went with 54 cc chambers on their new heads.
Here's my source:
http://www.grandsportregistry.com/lt1vslt4.htm
Jake
West Point ROCKS!
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Registered User
Joined: Jun 2004
Posts: 840
From: bakersfield ca.
well im not going to say what is right or wrong. im just going to say what makes sense to me.
the site you posted said that the lt4 has a .4cc larger CC and has a higher compression ratio. i didnt see where it talked about the pistons having shallower valve reliefs, but the gmpp LT4 heads (pn 12363287)are said to have a 54.4cc chamber and supposedly raise the compression to 11:1 on a stock bottom end LT1....
they are supposed to be the same head as what was on the grandsport. i checked the part numbers at gmpartsdirect.com and nothing came up using the PN given on the grandsportregistry page.
again, im not saying im right or wrong, but i dont always believe the guys who are self proclaimed experts.
the site you posted said that the lt4 has a .4cc larger CC and has a higher compression ratio. i didnt see where it talked about the pistons having shallower valve reliefs, but the gmpp LT4 heads (pn 12363287)are said to have a 54.4cc chamber and supposedly raise the compression to 11:1 on a stock bottom end LT1....
they are supposed to be the same head as what was on the grandsport. i checked the part numbers at gmpartsdirect.com and nothing came up using the PN given on the grandsportregistry page.
again, im not saying im right or wrong, but i dont always believe the guys who are self proclaimed experts.
Registered User
Joined: Apr 2007
Posts: 549
From: Lancaster, Texas
well im not going to say what is right or wrong. im just going to say what makes sense to me.
the site you posted said that the lt4 has a .4cc larger CC and has a higher compression ratio. i didnt see where it talked about the pistons having shallower valve reliefs, but the gmpp LT4 heads (pn 12363287)are said to have a 54.4cc chamber and supposedly raise the compression to 11:1 on a stock bottom end LT1....
they are supposed to be the same head as what was on the grandsport. i checked the part numbers at gmpartsdirect.com and nothing came up using the PN given on the grandsportregistry page.
again, im not saying im right or wrong, but i dont always believe the guys who are self proclaimed experts.
the site you posted said that the lt4 has a .4cc larger CC and has a higher compression ratio. i didnt see where it talked about the pistons having shallower valve reliefs, but the gmpp LT4 heads (pn 12363287)are said to have a 54.4cc chamber and supposedly raise the compression to 11:1 on a stock bottom end LT1....
they are supposed to be the same head as what was on the grandsport. i checked the part numbers at gmpartsdirect.com and nothing came up using the PN given on the grandsportregistry page.
again, im not saying im right or wrong, but i dont always believe the guys who are self proclaimed experts.
If you read farther down you'll see the information on why the CR is different between the two engines.
Look in the area where the piston info is listed; it speaks directly to the shallower valve reliefs on the LT4. It's the shallower valve reliefs that result in the higher compression. If you notice the pistons are different.
Jake
West Point ROCKS!
Thread Starter
Registered User
Joined: Jun 2004
Posts: 840
From: bakersfield ca.
guys who actually measured their stock heads were getting all kinds of different numbers. i bet that every LT1 that rolled off the line had a different CR. maybe thats why some LT1 camaros would stomp on others with similar bolt ons...
Registered User
Joined: Oct 2001
Posts: 2,525
From: SoCal
The moral is that every engine is different and will respond dissimilarly to mods - some work great for some and mediocre for others.
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