GM847 396 LT1 Build

[Badbird_96]

Ok so i want to build a motor for my ws6. Im going to get a bare block and buy the peices here and there and assemble it as time permits. I know i want a 396 lt1 and i know i want the gm847 cam but what i need is to feel the rest in. Basically info like what would be the best heads to use for a build like this or what size fuel injectors and throttle body do i need to keep it from starving out, stuff like that. I know motor stuff its just im not so good with building f.i. motors. Ive built from slant six dodges to 440s to 327 sbc to 454 bbc to 302 sbf to 460 bbf and even a couple 402 bbp just never an lt1 lol. I found a website with a complete motor but spiers thinks i can get the power they are claiming cheaper a different way so im going to build something better hopefully lol. Im going to post the specs cause this is going to be the blueprint for mine and if anybody sees something the think would be better or fill in missing info such as header choice just let me know. Oh and these are specs off that website. What all needs to be changed for the GM847 to work in this motor.


396 LT1 Specs



Peak Horsepower: 550 bhp @ 6300 rpm
Peak Torque: 490lb/ft @ 4000 rpm
Operating Range: 2300 - 6300 rpm
Compression Ratio: 11.5:1
Required Fuel: 91+ Octane Pump Gasoline


Block: Thermally cleaned and Stainless Steel Shot. Inspected by MPI process. Zero decked, bored, honed with torque-plates and pressure washed. Durabond cam bearings and pioneer brass freeze plugs installed.
4-bolt main caps and ARP main studs.

Crank: Eagle 4340 forged steel 3.875” internal balance

Rods: Scat 4340 forged steel I-beam, 6” length, floating pin

Pistons: Mahle forged with anti-friction coating

Rings: Mahle plasma-moly

Bearings: ACL H-series main and rod bearings

Core Plugs: Brass Pioneer core plugs

Lifters: Comp Cams Hydraulic Roller

Pushrods: Smith Brothers .083" wall hardened

Valve Springs: AFR 1.250", hardened retainers and locks

Rocker Arms: Comp Cams Pro Magnum Full-Roller 1.6 ratio with 7/16 rocker stud and guide plates

Timing Set: GM LT4 Extreme duty roller

Timing Cover: Factory Aluminum timing cover

Oil Delivery: Melling high volume pump, pickup tube and HD Drive

Oil Pan: Canton 6 qrt road race

Gasket Set: Fel-Pro Performance

Head Bolts: ARP Performance Hex Head

Intake System: Ported LT1 intake, 58mm Holley Billet Throttle Body, 30lb injectors, adjustable fuel pressure regulator

Ignition System: MSD Opti Spark, MSD 8.5mm plug wires, MSD Coil

Valve Covers: Polished Aluminum valve covers

Damper: SFI Approved Damper and steel hub

Water Pump: GM Water Pump with 160 degree thermostat

Flywheel: SFI Approved flex plate or std flywheel with ARP bolts

Cam Info

Manufacturer:
Comp Cams

Type:
Hydraulic Roller

Operating Range:
2300-6300 RPM

Idle Quality:
Good

Duration:
Intake: 236˚@ .050”
Exhaust: 242˚@ .050”

Lift:
Intake: .555”
Exhaust: .575”

Lobe Separation:
112˚

Head Info

Type:
AFR Eliminator 195cc CNC ported

Combustion Chamber:
64cc

Intake Runner:
195 cc

Intake Valves:
Stainless Steel 2.05”

Exhaust Valves:
Stainless Steel 1.60”

[Paulster2]

Several things I'd do different, but I'm not the expert. Your resume on different engines is pretty extensive, but the LT1 is not like other engines. It has reverse flow cooling (which I assume you know). With that, you can run higher compression than most any other engine out there while running pump gas (91-92 octane fuel). 12.5:1 and even 13.0:1 on pump gas on the street is not unheard of. The reason I bring this up is if the AFR heads you are looking at have 64cc chambers, you'll be lowering the CR of the engine. I believe the stock chamber is 54cc, so just a thought there. I don't know the flow specs on the 195 Eliminators. They may be able handle it, but most 396s need to have a lot of flow in order to perform to their potential (300cfm+). Some other things to consider:

I'm not sure if the Scat rods you have listed have cap screws (which I believe they do) or you might have problems with clearance on the cam. If they don't, you'd probably need a small base circle cut cam or you'll have interferance.
If you are running a HV oil pump, make sure run looser clearances to take benefit of it. (You probably know this from previous builds and what it should be).
People have less problems with head bolts than head studs.
You will probably need larger injectors. 30#ers are on the low end of what the engine will need. There are several injector calculators out there to help you figure out what you'd need.
Stick with an ACDelco Optispark. I don't know if MSD has figured out their issues, but there has been a lot of bad press about their offering. If you need to spin higher there are several options out there:

Dynaspark
LTCC conversion
LS1 ignition conversion

Hopefully others will chime in and give you some more advice. This is just some general things an "LT1 Newbee" might like to know. You might also get a book called, "How To Rebuild Small Block Chevy Lt1 Lt4 Engines (http://www.amazon.ca/Rebuild-Small-Block-Chevy-Engines/dp/1557883939)" which is an HPBook. There are a few gotchas about the LTx which this book will help you through.

Remember, these are only my suggestions, so take them as such. Hope they help.

[Twisted Z]

I would agree with much of the above post. You need to get the compression up to at least 12.0 to 1. Even with all the bad you hear about them Nothing beats an Opti on this engine. I am running a GM Opti with MSD cap and rotor. THAT is the key. Changing the cap and rotor on a regular basis just like you would any other hi-performance car.

I would bump up to at least the AFR 210s at 58cc's. I have measured stock many times and it is from 57-59cc's depending on the valves used. The GM847 is a decent cam, i have ran it my self, but we made more power and TQ with a .610 lift 230/230 cam on our 396. This car laid down 447RWHP through an unlocked 4L60E and a 12 bolt. It had great street manors as well.

I would dump the expensive Canton Oil pan for a much better designed (IMHO) B&B pan. Unlike the canton I have not had a B&B leak. The down side is no oil level hole...but that is easy to fix ;)

Make sure you take the time to properly setup the valve train. No matter what ANYONE tells you it is NOT a bolt on afiar. I usualy spend a few hours doing this and I use Isky adjustable guide plates. Setup the tip alighnment then weld the plates. Next setup the Valve sweep properly as seen here.

http://www.mid-lift.com/TECH/TECH-Installed-G1.htm


This will all give whisper quite and powerful results ;)

One other thing I would look into is a single plane converion ;)

Good luck and keep us up to date!

[QC97Z]

Small base circle cam will be necessary (and that cam doesn't really have very high lift numbers....I'd be going MUCH higher than .555/.575)
If you're looking to be able to REALLY make big power, you might need to have a solid roller setup. This would require more valvetrain maintenance than a hydraulic setup.

Scrap the I-beams and get some quality H-beams. H-beams are a much better design, and if you're going for higher compression (that would be the smart thing to do) you'll need a strong bottom end.

30# injectors won't be enough. 55# might be more in the right realm, considering the other changes to the build that should be made for more power.

The 195cc heads aren't NEARLY enough. I'd be looking at AFR 210's at minimum, if not the 227's. AI has nice Trick Flow CNC ported 215's that would work well also. In addition, a smaller combustion chamber is what you need, or a domed piston. That CR needs to climb.

The MSD opti would be alright, if you made the correct modifications to it. The rotor screws need to be replaced with #10 hex head cap screws cut to the longest length possible without interfering with the opti's body. They need red loctite, and need to be tightened TIGHT. Also the cap needs to have the square cross-sectional gasket, not the round type, so they don't leak. All new units now come with the square seal. If done right, the MSD opti can get you screaming high in the RPM's and still be stable.

This is all my opinion, but I planned for an N/A 396 build and did TONS of research. I ended up going F/I 383, mostly because my power goals wouldn't be met with an N/A 396 and I wanted a hydraulic roller setup. I think if you went with the blueprint you originally posted, you wouldn't even hit close to 500 BHP (compared to the 550BHP listed). I just don't want to see you disappointed going through all this money and trouble to build a setup that will only make 425-ish at the wheels.

[dsmawd350]

Im gonna assume your trying to make max power since your building a 396 stroker in the first place so heres my thoughts.

on a 396 id also ditch the off the shelf gm847 and get a big custom grind cam. go with some bigger heads. 210cc or bigger. Also ditch the hardened pushrods for a set of stronger chromoly one. I had comp hardened PRs in my old motor and mushroomed one with a cc306 and comp 1.6's. switch to chromoly pr's and never had another problem. Another thing I'd consider is switching to a single plane and 4bbl throttle body and possibly switching to a conventional distributor.

[Badbird_96]

Thanks for all the info. The specs i listed are off a website for a engine company. I know alot about stock lt1s just not about modding one. I just thought it may be a good staring place for a build since i dont know anything about them. Plus there are so many different heads and cams and etc that i didnt have a clue where to look first or what would go best together lol. The only reason i wanted the gm847 was because the idle just sounds mean and i have seen some pretty fast n/a cars running it. But bigger is always better.... well most of the time lol.

Plus another idea i was throwing around was bolting on a supercharger. I was told going boosted it would be easier to do a smaller build but im loving the thought of a supercharged 396. Just the thought seems fast lol

[RamAir95TA]

Sounds to me like you need to slow down and figure out what you're building this for. No offense, of course.

[Paulster2]

Sounds to me like you need to slow down and figure out what you're building this for. No offense, of course.
I couldn't agree more.

[QC97Z]

I couldn't agree more.

X 3. The difference between going N/A and boosted is at LEAST double in budget MINIMUM. The entire blueprint of the motor will change if you decide to boost. Do some more research, sit down, and THINK about what you want in the long run.
You need to know that a forced induction build will cause more issues/encounters you have to overcome than an N/A build, and the tuning will be much more extensive. You'll need a good, reputable tuner that you can get the car to for tuning. Mail order stuff only gets you so far.
You also need to know that the LTX PCM only goes so far with boost. So if you decide you want boost, and you want to boost a lot, you may need to explore the EFI connection option (swap to LSX PCM and related goodies), which is also more expensive.
Again, think about what you want in the long run. With the options you're talking about, you're at the fork in the road. You take one way or the other, and don't look back.

[Twisted Z]

Sounds to me like you need to slow down and figure out what you're building this for. No offense, of course.

X4

For FI I would stick with a shorter 3.75 stroke for better piston pin placement and less side loading on the cylinders. You could rock the bottom of the block to help but they are still factors.

I would still go with a 210 head and a different cam ;)

[Badbird_96]

No offense taken lol thats why im asking yall. I know what i would like to do and thats going supercharged but what im really wondering is if its worth the hassle or just sticking n/a. Thats what im having trouble deciding on. I had decided to go n/a thats why i posted those specs and asked about it but i had originally wanted the supercharger. I just dont know if it would be better to go which way. I think i would have better luck and reliability going n/a but i love the sound of a s/c, especially with a big cam. Let me ask this. If you had a really built formula that burnt and you got this ws6 which is a nicer car but so much slower what would you build to fix it?

(Btw im not being a jerk if it comes off that way lol just couldnt think of another way to word it. I just really need some info on what would be best for my build.)

Oh and as for what im planning on doing with the car cause im sure thats the first thing someone will ask lol, im planning on mainly just driving it maybe a little drag and road course action but im one of those people who likes having a fast daily driver lol.

Oh and im gonna tell yall what i was told was done to my formula when i got it and see if that would be an option. I was told the car had a 380hp crate lt1 bored 30 and had the heads shaved 20. It supposedly had a 1200ft lb racing clutch and 3.73 gears. It still had factory exhaust and everything else. I was told it ran 8.5s in the 1/8. I dunno cause i worked 2nds and never got to run it but my buddies ls1 ss ran 8.9s and i walked him in it lol. Basically i want something faster than that so i can hold my own against ls1 cars. Any ideas?

[RamAir95TA]

A supercharged 383 done right will cost you twice as much as a N/A LT1.

Speaking from experience, there isn't much that can touch a 455whp N/A stroker. If I had to do it all over again, I wouldn't change a thing.

[QC97Z]

A supercharged 383 done right will cost you twice as much as a N/A LT1.

Speaking from experience, there isn't much that can touch a 455whp N/A stroker. If I had to do it all over again, I wouldn't change a thing.

^^ What he said. I was originally planning a built 396 N/A, and my budget for everything (including full driveline, suspension, etc) was about 13K.
I decided to go 383 S/C, caught pretty good deals on almost everything I bought, and I'm up to $25K. All I have left is $600 worth of dyno tuning.

a 455RWHP stroker would be sweet, I can guarantee that. I haven't driven a small block stroker, but I've driven a few big block camaros and chevelles with 450-650 RWHP, and there's nothing like a huge N/A motor.