Pro's/Cons of building an iron 408 vs my 347 for D1SC
06-18-2012, 09:36 AM
#1
Pro's/Cons of building an iron 408 vs my 347 for D1SC I picked up an 01 SS a few weeks ago as something to play with and am wanting to start getting into FI. I've done a ton of H/C LS setups but have never tried FI.
My question is regarding the engine. I am planning on 700-800 RWHP out of this. I really want to keep the weight down. Doing UMI K member/A arms/AC delete/Speed Inc carpet/ removing rear seats/Spare tire/ and any other area's that I can cut weight out of the car. Want to be low 3,xxx's. Already have a cage going in which is about 85 lbs plus the blower setup (What's a D1SC setup weigh?).
Doing a Midwest Rear setup so no added weight there. I see a lot of guys doing the iron blocks for the FI setup, but have also seen quite a few guys say that unless you plan on running 8's, you can stick with the stock aluminum LS blocks.
So are there any pros in going with the 390 or 408 over just throwing forged rods/pistons in my 347?
Is 700-800 RWHP and low 10's safe and doable with a forged 347? I will be running an alky setup as well.
Are ARP main studs needed? I will for sure be doing ARP head studs.
Thanks
My question is regarding the engine. I am planning on 700-800 RWHP out of this. I really want to keep the weight down. Doing UMI K member/A arms/AC delete/Speed Inc carpet/ removing rear seats/Spare tire/ and any other area's that I can cut weight out of the car. Want to be low 3,xxx's. Already have a cage going in which is about 85 lbs plus the blower setup (What's a D1SC setup weigh?).
Doing a Midwest Rear setup so no added weight there. I see a lot of guys doing the iron blocks for the FI setup, but have also seen quite a few guys say that unless you plan on running 8's, you can stick with the stock aluminum LS blocks.
So are there any pros in going with the 390 or 408 over just throwing forged rods/pistons in my 347?
Is 700-800 RWHP and low 10's safe and doable with a forged 347? I will be running an alky setup as well.
Are ARP main studs needed? I will for sure be doing ARP head studs.
Thanks
06-18-2012, 01:58 PM
#2
TECH Resident
plenty of people have gone 9's with 347s. Iron is tried and true, and been around since the beganing of racing. So the old motto of if it aint broke dont fix it plays a part. On the other side if you are concerned with weight, go with the ls1. With the LS1 you will see anywhere from 650-750rwhp. and with the 408 you should see 700-850rwhp. Good luck with decision!!
06-18-2012, 02:00 PM
#3
First off: YAY! You're going boost!
About your 390 vs. 408 Question. The 390 will be the "stronger" motor. Since it uses a shorter stroke (3.8" vs. 4") the piston tends to be "longer" (the way I see it), and is just a stronger motor.
347 Question: At the end of the, day running a stock stroke forged motor will be better, its less harsh on parts because of the reduced stroke.
Personally I wouldn't call it "safe", anything at that amount of power won't be "safe".
Main Studs are a MUST. I would actually have the Mains Pinned at that level.
If it were me I would do a 370. Stock crank, Forged Rods, and Pistons and be set. Its a proven combination.
About your 390 vs. 408 Question. The 390 will be the "stronger" motor. Since it uses a shorter stroke (3.8" vs. 4") the piston tends to be "longer" (the way I see it), and is just a stronger motor.
347 Question: At the end of the, day running a stock stroke forged motor will be better, its less harsh on parts because of the reduced stroke.
Personally I wouldn't call it "safe", anything at that amount of power won't be "safe".
Main Studs are a MUST. I would actually have the Mains Pinned at that level.
If it were me I would do a 370. Stock crank, Forged Rods, and Pistons and be set. Its a proven combination.
06-18-2012, 03:24 PM
#4
Im not sure if Main Studs are necessary for 1000 engine hp.
Ive read quite a few using just ARP bolts, and some even using stock main bolts on 700-800rwhp setups.
Remember, using main ARP bolts /studs = align honing is required.
Pinning is always a good idea.
06-18-2012, 06:13 PM
#5
Well, he cant do a 370 as he clearly doesnt have a 6L block. hence the 347 inquiry. I would agree with you LS2 hands down, but if a LS1/lS6 is at his disposal, id go that route.
Im not sure if Main Studs are necessary for 1000 engine hp.
Ive read quite a few using just ARP bolts, and some even using stock main bolts on 700-800rwhp setups.
Remember, using main ARP bolts /studs = align honing is required.
Pinning is always a good idea.
Im not sure if Main Studs are necessary for 1000 engine hp.
Ive read quite a few using just ARP bolts, and some even using stock main bolts on 700-800rwhp setups.
Remember, using main ARP bolts /studs = align honing is required.
Pinning is always a good idea.
Main studs are absolutely necessary for an engine build of this caliber, its "cheap" insurance. Yes he will have to have it honed but if he is doing a motor build he will have to have it machined anyway. Might as well do it right.
06-18-2012, 06:51 PM
#7
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06-18-2012, 09:56 PM
#10
For what your looking for a forged 347 will do just fine. For ease of cost stick with the LS1 block....if you want to go with a bigger motor, go with a 390-408ci LS2. At that level your deff going to want main and head studs. A D1SC will perform a little better on a smaller motor as well. You'll most likely need to run around 17-18psi to make into the 700+ range but shouldn't be to hard. Stock crank, good set of rods and pistons and a good aftermarket head with a thicker deck will do the trick. You can get away with a stock casting head but for relaibility I'd go with an aftermarket head. Did you take in account the fuel system, fuel type, compression? Sounds like it'll be a decent build!
06-19-2012, 08:58 AM
#12
You should be in the 10's solidly now, you had a chance to run it yet? We should get together sometime soon man, haven't seen ya in forever
06-19-2012, 10:50 AM
#14
06-19-2012, 02:09 PM
#16
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just to let you all know in case you haven't heard yet but AES doesn't do the 390 anymore due to the crank size being discontinued...thats what I was told by them last month, now they have a new beast they are doing and its a tad bit bigger, the 399...also unfortunately if you try to get a callies magnum crank right now your SOL! ask me how I know. When I talked with Bryan from AES he told me that callies won't have those cranks available for about 4-5 months so my only option and maybe some of you considering it, is save you the headache and do a 408 because the 4" cranks are readily available. Hope this helps.
06-19-2012, 07:00 PM
#17
just to let you all know in case you haven't heard yet but AES doesn't do the 390 anymore due to the crank size being discontinued...thats what I was told by them last month, now they have a new beast they are doing and its a tad bit bigger, the 399...also unfortunately if you try to get a callies magnum crank right now your SOL! ask me how I know. When I talked with Bryan from AES he told me that callies won't have those cranks available for about 4-5 months so my only option and maybe some of you considering it, is save you the headache and do a 408 because the 4" cranks are readily available. Hope this helps.
^ yeah I bought the last 390.
----and to the OP...as stated the reason I went with smaller cubes is because it allows for the thicker journals etc.........the 398 is the new edition. you will have to wait for it, but it will be worth it. they do great work, and are everything you could hope for out of a builder. I mean, they build top fuel motors, so I am sure they can handle our little boost motors! plus the way I look at it, if the d1sc performs as well as it does on the 347...the f1-a should be a nice piece for the 39x's
06-19-2012, 07:56 PM
#18
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^ yeah I bought the last 390. ----and to the OP...as stated the reason I went with smaller cubes is because it allows for the thicker journals etc.........the 398 is the new edition. you will have to wait for it, but it will be worth it. they do great work, and are everything you could hope for out of a builder. I mean, they build top fuel motors, so I am sure they can handle our little boost motors!
plus the way I look at it, if the d1sc performs as well as it does on the 347...the f1-a should be a nice piece for the 39x's
----and to the OP...as stated the reason I went with smaller cubes is because it allows for the thicker journals etc.........the 398 is the new edition. you will have to wait for it, but it will be worth it. they do great work, and are everything you could hope for out of a builder. I mean, they build top fuel motors, so I am sure they can handle our little boost motors! plus the way I look at it, if the d1sc performs as well as it does on the 347...the f1-a should be a nice piece for the 39x's
06-20-2012, 12:22 AM
#19
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347
PRO -
Cheaper; stock crank is fine.
Can make as much as power as a 390/408, but it will need more boost.
Lighter.
No drilling/tapping holes for bracket.
CON - Give up some torque down low
390/408
PRO -
Easier to make the power because it doesn't require as much boost.
More torque.
CON-
More expensive.
More weight.
Having to drill/tap holes for bracket.
PRO -
Cheaper; stock crank is fine.
Can make as much as power as a 390/408, but it will need more boost.
Lighter.
No drilling/tapping holes for bracket.
CON - Give up some torque down low
390/408
PRO -
Easier to make the power because it doesn't require as much boost.
More torque.
CON-
More expensive.
More weight.
Having to drill/tap holes for bracket.
06-28-2012, 12:59 PM
#20
I went with the forged 347 route due to weight and cost, although for the money I spent to rebuild my LS1 as a 347, I could have bought a used forged iron 370-390. I will be lowering the compression down with new heads (instead of extremely milled 241s for NA use) and installing a D1SC w/3.4" blower pulley, 7.25" crank pulley, and a very good belt tensioner setup. I have the headunit and pullies, need to fab cold side, buy fuel system, T56 swap+build, and 9" rear end.
Nice setup. Any more info on the heads? I'm in the market for some and would like to know the specs of the Patriots you went with and if the engine is o-ringed:
Code:
347ci fully forged built by Mike @ Rapid Motorsports Patriot Stage 3 heads with gold double valve springs ECS Blower Cam TSP Ported/shimmed LS6 Oil Pump (50psi at idle) Rollmaster Double Roller Timing Chain Chromemoly Pushrods ARP Head studs, rodbolts, mains, etc. throughout entire motor LS6 intake Custom crank case ventilation setup with AN -10 lines and 2 Moroso catch cans with breathers Powdercoated Valve Covers A&A/custom F1 Procharger setup w/4.0" Pulley A&A Latest Procharger Bracket 4" Powdercoated Charge/Intake Piping with huge K&N filter Procharger Big Red Race Valve A&A 8-Rib Setup with Innovators West 8" 10% OD Balancer RSI/Custom Fuel System with billet hat and twin in-tank pumps, all black fuel lines, filters, and fittings. Speed INC High Flow Fuel Rails Fuel Lab Fuel Pressure Regulator w/ Carbon Fiber Gauge 83#/hr Motoron Fuel Injectors AIS Trunk Mounted Boost Referenced Methanol System w/ stainless braided line. Has progressive controller and holds 1.5 gallons. New Optima Red Top Kooks 1 7/8" Longtube Headers Kooks 3X3" Off-Road X pipe B&B Bullet Exhaust Built M12 with Textrallia Twin Disc Clutch