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GPI 281cc Heads Cam LS3 what do you think it will make

 
Old 02-07-2019, 09:19 AM
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Default 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 [email protected] I had to swap clutches and last time I ran made 3 passes and went [email protected] on 93 with a splash of 110. Just curious what you guys think its capabilities will be.
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Old 02-07-2019, 10:10 AM
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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?
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Old 02-07-2019, 10:24 AM
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Originally Posted by LSleeper1500 View Post
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?
Cars 60% together. hopefully hit the dyno by the end of February. I think it will make 530+ honestly. Compression is bumped up to 11.5:1ish and that should help the E85 gains a little.
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Old 02-07-2019, 10:35 AM
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532whp, and the LOD intake will lose vs the FAST.

There is no way this makes less than 500whp imo.
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Old 02-07-2019, 10:43 AM
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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.

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Old 02-07-2019, 11:45 AM
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Won't be lazy if cammed correct.
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Old 02-07-2019, 11:48 AM
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Originally Posted by Smokey B View Post
Won't be lazy if cammed correct.
It would be an airflow issue, not a cam issue.

Although his proposed cam and short-runner intake choices won't be doing him any favors.

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Old 02-07-2019, 12:20 PM
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Originally Posted by KW Baraka View Post
It would be an airflow issue, not a cam issue.

Although his proposed cam and short-runner intake choices won't be doing him any favors.

KW
I donít 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.
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Old 02-07-2019, 12:27 PM
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281cc is only a 6% increase on stock port volume.

Last video I saw of this car it was doing 6000 rpm clutch dumps with a tilton racing clutch. I think the parts selection is pretty solid and the car will probably go 10.0 or even sneak out 9's.
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Old 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.
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Old 02-08-2019, 07:12 AM
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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?
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Old 02-08-2019, 07:40 AM
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Originally Posted by Double06 View Post
Whos (company) titanium retainer was it? Did it break in half or something like that or let the valve slip through?
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.
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Old 02-12-2019, 04:35 PM
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Originally Posted by lazerlemonta View Post
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 [email protected] I had to swap clutches and last time I ran made 3 passes and went [email protected] on 93 with a splash of 110. Just curious what you guys think its capabilities will be.
Following. I did a slightly different build in mu 2015 1LE before i went with more displacement. It was PRC 260 heads, 235/251 113LSA it made crazy power. One thing you should be away of is those heads are just like the FED 286cc they have a large port more like a blower port than a NA power it will still make a lot up top but the port isnít as effeciant as a smaller port design. Just because it has the big cc number doesnít mean it will be the best for the set up. Also i run the actual Frankenstein version and you will need to port match fast intake to it so you donít have a turbulence issue. My new build, Itís a 417 Ci, 12.5:1 comprsssion,262/275 @50 110 LSA, fast intake medium runner. goes on dyno soon
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Old 02-13-2019, 06:52 AM
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542.65whp!
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Old 02-13-2019, 07:34 AM
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Originally Posted by lazerlemonta View Post
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. ......
You had titanium retainers and considered it a bolt on?
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Old 02-13-2019, 08:20 AM
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552 rwhp plus tax
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Old 02-13-2019, 08:37 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.
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Old 02-13-2019, 08:49 AM
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Originally Posted by ddnspider View Post
You had titanium retainers and considered it a bolt on?
Read my signature sir. Bolt ons with a few internal mods.... I had 1.85 rockers, valve springs, retainers and a crank scraper.
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Old 02-13-2019, 08:56 AM
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Originally Posted by lazerlemonta View Post
Read my signature sir. Bolt ons with a few internal mods.... I had 1.85 rockers, valve springs, retainers and a crank scraper.
Gotcha, thanks.
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Old 02-13-2019, 09:08 AM
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Originally Posted by JakeFusion View Post
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.
This is just for data for GPI and myself. They wanted to see the results of this package on my car. I already have 3 intakes for my LS3. We just have to figure out which will work best for my goal. I have a fast with long and mid length runners plus an LOD Speed works we have modified to fit a C6. Really looking to spin it 75-7600 if it is hanging on there to get me in the RPM range for the trap speeds I intend on achieving. I think it should make 480 torque on E85 pretty slick and carry it better as well.
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