08-01-2012, 11:45 AM | #1 |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
Posts: 379
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question: for the turbo crowd
Ok here goes. If I increase my displacement from a 376 to 418 cube, and also lower my compression to a 9.5 from a 10.7. Will I gain more power on the 9 psi I have..or lose power due to my compression being lowered?
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08-01-2012, 12:03 PM | #2 |
Drives: ETMC built 700+hp Twin Turbo LS3 Join Date: Apr 2010
Location: Killeen, TX
Posts: 682
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you will wont make the same power at the same PSI if you lower the compression rate. You will have to up the boost. The experts should chime in shortly. Also make sure you get the right size turbo for 418ci so you don't have problems over spinning the turbos.
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08-01-2012, 12:12 PM | #3 |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
Posts: 379
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I have gt 3586 i believe. Its the ips twins with ceramic bb and they are mid sized, so I think I am good. However, I am a whee bit disappointed at what u just said. I want more not less of of course...thank you for the reply. I await the experts to come on board for guidance. PS my builder also told me this, that i would lose power..ugh..no BUENO !
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08-01-2012, 12:23 PM | #4 |
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Drives: 2010 SS, 06 SRT10 Ram Join Date: Nov 2011
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Lowering compression you will lose power unless you compensate by upping boost. As stated, make sure you have a big enough turbo, if not you will overspin and boom goes your turbo.
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08-01-2012, 12:27 PM | #5 |
need....more....hp
Drives: The Neighbor Hater Join Date: Dec 2010
Location: San Mateo, CA
Posts: 4,091
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I'm running the same turbo kit with a 418. At 9psi I'm making over 800whp. I'd be surprised if you were running above that on a 376 block. Get a boost controller and crank it up. Since its a built block it can handle a lot more than your 376.
Going from a 10.7 to 9.5 CP will lower your power, but you also need lower compression if you want to up your boost in the future.
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Mast Motorsports Built LS3 Stroker 418, IPS GT35R Twin Turbos, Exedy GTO4XD Twin Disc Clutch, Aeromotive A1000 Eliminator Stealth Fuel Pump, AEM Meth Injection, DSS 1400hp Axels, BC Coilovers, Pfadt & BMR Suspension, Hawk HPS Pads, Drilled/Slotted Rotors, Hurst Shifter, Custom Roll Cage by Blu808, T3 Ports, 22" Custom Concave Mesh Rims |
08-01-2012, 12:43 PM | #6 |
Drives: CGM,twin turbo, cam 2010 SS/RS Join Date: Mar 2011
Location: ROCKMART, GA
Posts: 2,185
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It would be hard for anyone to tell you exactly.. Cam profile, piston design etc.. will all play a part in this. If it was mine and i was using the ls3 block I was just stay with the 376 cubes and save the money and have a happier motor for longer.
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08-01-2012, 12:47 PM | #7 |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
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Hi Pryo...i got ya num unless u changed it. I might just buzz ya. I know I will have to boost higher. But I am glad you have the same set up Pyro. I am virtually copy catting you Hope I dont get you upset .lol My confusion is this. Even though I lost some compression. I upped the cubes. So I am supposed to get more torque at least in the bottom, and hence I can also increase my boost. Would I not get more power at the same psi over all ? If you are running 9 psi and get 800 rwhp, thats more power in my book. I am just getting 650 rwhp and thats with a cam also, with the stock ls3.
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08-01-2012, 12:54 PM | #8 |
50 Shades of Prey
Drives: TT/SS Join Date: Oct 2010
Location: Between 10 and 20 PSI
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It would most likely make more power at the same psi with the increase in cubes but like JLE58 said other factors will come into play. In my opinion I'd be surprised if you made less at the same psi. At 9 psi on a low compression 418 your turbos will be moving more air then with the 376 to get to that same 9psi so I personally feel you would make more power. Are you doing heads also? That would make a big difference too.
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08-01-2012, 01:38 PM | #9 | |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
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Quote:
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08-01-2012, 01:41 PM | #10 |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
Posts: 379
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Under normal conditions i agree but since i was doing a repair/overhaul..i figured I just start from scratch and step up cubes. If i can boost 20 psi with this set up, and (offcourse i have to chnage fuel pumps, and thing) I think I can hit a possible 100 rwhp or close and have longevity all in one...this at least is my goal. PS this is a street car, not a 1/4 mile car. I just want a poor man Buggati
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08-01-2012, 01:43 PM | #11 |
Drives: 2010 Camaro 2SS/RS Join Date: Sep 2009
Location: Down South
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In your case it is hard to know for sure since increasing the displacement from 376 to 418 cubes would add hp/tq but lowering the cr reduces power.
Lowering the cr reduces power but it allows you to run more boost given the same fuel. So if you are running 9psi now but are lowering the cr one full point. The lower cr would loose about 2% power(per 1 point cr) but you would be able to up up the boost 1-2 psi giving you an overall higher hp number. So since you are turbo'ed you should be gaining 20-30 hp per lb of boost.
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08-01-2012, 01:46 PM | #12 | |
need....more....hp
Drives: The Neighbor Hater Join Date: Dec 2010
Location: San Mateo, CA
Posts: 4,091
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Quote:
If you go from a 376 to a 418 with SAME CP, then you will be making more power....that makes sense if you are going NA, but if your upping the cubes and have twin turbos, you want to lower your CR, and will lose N/A power. those turbos will produce a ton of torque! you would not believe it. Trust me, with the kit IPS builds, your 418 will love it. Turbos produce massive amounts of torque (when i was detuned at 8psi, i made 750whp/810wtq at 4000rpms). I'm not sure on your engine producing more torque, really depends on what its built with, although going to a bigger engine will produce more torque overall. Have you looked at heads? I would recommend 12* 6-bolt heads. They flow amazing!
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Mast Motorsports Built LS3 Stroker 418, IPS GT35R Twin Turbos, Exedy GTO4XD Twin Disc Clutch, Aeromotive A1000 Eliminator Stealth Fuel Pump, AEM Meth Injection, DSS 1400hp Axels, BC Coilovers, Pfadt & BMR Suspension, Hawk HPS Pads, Drilled/Slotted Rotors, Hurst Shifter, Custom Roll Cage by Blu808, T3 Ports, 22" Custom Concave Mesh Rims |
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08-01-2012, 01:56 PM | #13 |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
Posts: 379
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Pyro the heads u are speaking of...these 12* heads..who makes them, and how much $$. I am running a texas speed block. So far all looks well. Wiseco turbo pistons, tools steel pins, and steel top rings. I have a callies compstar. The dragon is really for the all out race guy. I knows it is better but I think for my intent its money i can save. i wont be beating my car up often. I just like to press her down here and there. BTW your words on my hp out look are encouraging. I hope you are right in my case to. I have callies rods, and if u missed it i explained for cyber my head set up thus far.
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08-01-2012, 01:57 PM | #14 |
Drives: 2011 SS Join Date: Nov 2011
Location: new jersey
Posts: 379
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oh i forgot I also arped everything, and got the arp stud head kit with ls9 gaskets as my setup.
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