GPI 281cc Heads Cam LS3 what do you think it will make
02-07-2019, 09:19 AM
#1
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GPI 281cc Heads Cam LS3 what do you think it will make Was on the dyno a few weeks ago with my C6 and had a titanium retainer fail, dropped #7 intake valve and luckily it went back into the head, bent and stuck. I reached out to GPI and talked with Ryan a bit and ended up doing their 281cc heads (stock ported) milled .042 with .040 cometic gaskets, SS4 fly cut cam 236/254 .646 .637 111+4, johnson short travel lifters, manton series 5 11/32 push rods, smith brothers trunnion kit for stock rockers and BTR .660 dual platinum springs with titanium retainers. I am going to start with the mid runner fast and swap to the L.O.D. intake on the dyno for comparison. Car has electric water pump, crank scraper, tri y headers 2 x 2 1/4 x 3, 3" x pipe, flex fuel, 25% ATI pulley, no belt tensioners, 102tb, rps twin carbon/aluminum flywheel, fly cut pistons .120 and 4.10 gears. My car made 453SAE with the bolt ons and 1.85 rockers and went a best of 10.58@131. I had to swap clutches and last time I ran made 3 passes and went 10.8@128 on 93 with a splash of 110. Just curious what you guys think its capabilities will be.
02-07-2019, 10:10 AM
#2
I've seen some of the stuff GPI has put out on their social media.. Crazy numbers. I'd think you'll be in the 480+ rwhp range easily with the SS4. That's just a low guess.. Probably crack 500 rwhp if you already made 450 rwhp with your old setup. I know it's a different platform but I think they made like mid 550 rwhp on a H/C LT1 the other day.. Again, different platform but just cool to see those kind of number's. When do you plan to dyno?
02-07-2019, 10:24 AM
#3
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I've seen some of the stuff GPI has put out on their social media.. Crazy numbers. I'd think you'll be in the 480+ rwhp range easily with the SS4. That's just a low guess.. Probably crack 500 rwhp if you already made 450 rwhp with your old setup. I know it's a different platform but I think they made like mid 550 rwhp on a H/C LT1 the other day.. Again, different platform but just cool to see those kind of number's. When do you plan to dyno?
02-07-2019, 10:43 AM
#5
281cc Intake runners is a lot of porting for the OEM heads and stock displacement LS3.
I would expect it to be needlessly lazy on the low end. That a problem ONLY if this car is gonna see significant street duty.
That said, I'd expect it to be strong up top......like in the 540 rwHP range through what I suspect is a M6 trans.
KW
I would expect it to be needlessly lazy on the low end. That a problem ONLY if this car is gonna see significant street duty.
That said, I'd expect it to be strong up top......like in the 540 rwHP range through what I suspect is a M6 trans.
KW
02-07-2019, 12:20 PM
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I don’t think I will be stalling in traffic by no means. It has a 26 pound rps and 4.10s. It will get to 2k instantly and from there it will make more torque then it did stock. Should not be a issue. Intake choice is for me to get through the traps making power at 135+ mph. This is my daily and it sees some track days.
02-07-2019, 10:21 PM
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Time to update that sig... I'm with you guys guessing in the mid 5's. And I think it'll end up doing better with the fast vs the LOD, but we will see. With the vette weight, even if it is a bit lazy off idle, likely won't matter too much.
02-08-2019, 07:12 AM
#11
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Whos (company) titanium retainer was it? Did it break in half or something like that or let the valve slip through?
02-08-2019, 07:40 AM
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They were BTR retainers but they had about 50k miles of service and the spring slipped through. Honestly they should have been changed but i seen no sign a fatigue when i put the roller rockers back on in November. I was in the process of doing a intake test for months so i could install my cam and my time just ran out.
02-12-2019, 04:35 PM
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Was on the dyno a few weeks ago with my C6 and had a titanium retainer fail, dropped #7 intake valve and luckily it went back into the head, bent and stuck. I reached out to GPI and talked with Ryan a bit and ended up doing their 281cc heads (stock ported) milled .042 with .040 cometic gaskets, SS4 fly cut cam 236/254 .646 .637 111+4, johnson short travel lifters, manton series 5 11/32 push rods, smith brothers trunnion kit for stock rockers and BTR .660 dual platinum springs with titanium retainers. I am going to start with the mid runner fast and swap to the L.O.D. intake on the dyno for comparison. Car has electric water pump, crank scraper, tri y headers 2 x 2 1/4 x 3, 3" x pipe, flex fuel, 25% ATI pulley, no belt tensioners, 102tb, rps twin carbon/aluminum flywheel, fly cut pistons .120 and 4.10 gears. My car made 453SAE with the bolt ons and 1.85 rockers and went a best of 10.58@131. I had to swap clutches and last time I ran made 3 passes and went 10.8@128 on 93 with a splash of 110. Just curious what you guys think its capabilities will be.
02-13-2019, 08:37 AM
#17
On E85 you could touch 540. GPI has seen 540 with E85 on their small bore LS7 MAX package with a similar cam. I don't imagine the heads are that much different... but they did that with the long runner MSD and had 500+ torque numbers too. I'm surprised they didn't steer you that way as the MSD on a 376 still runs to 7400.
02-13-2019, 08:49 AM
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02-13-2019, 09:08 AM
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On E85 you could touch 540. GPI has seen 540 with E85 on their small bore LS7 MAX package with a similar cam. I don't imagine the heads are that much different... but they did that with the long runner MSD and had 500+ torque numbers too. I'm surprised they didn't steer you that way as the MSD on a 376 still runs to 7400.