Things to Consider Before Going Forged
By: David Simpson
Note: this is not how to put together an engine but how to go about it. Helps give you an idea of the costs and things to look out for.
You can make more HP safer when going forged, but just like any platform their steps that need to be taken, so your investment is worth it. Experience is key here. Whether your doing it or a shop, you all need to know specific details about engine building on the GM LTG 2.0.
First: you need to commit to your build. This step is serious, because no matter if you do it or a shop does it, it’s going to cost a lot of money! Period. Go all out! Done correctly with proper mods installed.
If you plan on building an engine before your oem takes a shit, you save money on having to order a used block from a junkyard. No sense in added expenses. If you're around 350whp with current mods and want more HP, then be prepared to spend $8k-$15k🤬. It costs a lot more money to make more hp the safer way.
If you are still interested in making a 500hp+ car then you must do the following:
Start with a good motor. Have the block sent out to a reputable performance shop/engine machine shop to get cylinders honed and head/ deck planned. This will be better than OEM specs. Smoother and flatter surface. (helps eliminate imperfections on the block)
Purchasing forged rods and pistons, There are a few options now available. I would personally say ZZP H-Beam rods, along with a set of JE Pistons. You will more than likely want the oversized bore, as LTG castings usually need a good amount of machine work.
Rods:
-ZZP
-Molnar
-MaxSpeed
-Wiseco Boostline
Pistons:
-ZZP
-JE
-Diamond
-CP Carillo
Neutral balance shafts: is deciding whether to get neutral balance shafts. Although you can increase your higher rmps from 7000 to 8000 rmps. Its cool but not necessary because what you want is the less weight rotational mass=more hp and it will come on throughout the hp range. The Ltg 2.0 doesn’t like high rmps range. But having these balance shafts support them higher rmps ranges.
CAMS: stage 2 or 3 will work along great with OEM injectors and hpfp. Currently, I use stage 3 cams.
The ZZP Stock Cam bigger fuel lobe, is more for OEM stock motor gains, and has been able to make around 475rwhp on basically OEM fueling(the exception is ZL1 in-tank). I recommend with stage 2 or 3 cams when building a forged engine.
Valve springs are a must. Need stronger valve springs to handle the higher hp pressure your engine will produce. If not your valves will float and not close properly causing all kinds of issues.
Head Gaskets (ZZP offers two types: OEM and upgraded. With an upgraded gasket for the head you be able to run more boost), Exhaust manifold gasket, rocker arms, valve seals, and lifters all depend on miles on your current engine you plan on using for your build. Higher mile the engine then just buy all new engine support replacement parts.
ZZP has tons to offer when looking for a one-stop shop to get everything, Their prices are more than reasonable. You don’t have to get new valves, but it’s nice to start with all new stuff because it will all play a factor in your results. Old parts most likely have improper wear. Starting new helps with proper wearing.
ATI Ltg 2.0 Super Damper: This helps with absorbing vibrations in the camshaft. Smoother engine efficiency and helps with longer engine life.
Zzp head stud kit: helps with dealing with the higher pressures and hp your engine will be producing. Keeps it together.
Torquing the nut-bolts to specs
1st pass 25 ft/lbs
2nd pass 50 ft/lbs
3rd pass 80 ft/lbs
Torque sequence:
10 - 6 - 2 - 3 - 7
9 - 5 - 1 - 4 - 8
Timing chain: buying new timing chain and sprockets will help with wearing all your new parts together properly. If you use old oem ones off a high mileage engine, then parts will be worn and stretched out, as well as, be weak and possibly break. So buy new.
Building the engine: As mentioned earlier, whether you're tackling the engine build yourself or entrusting it to a reputable engine shop, a critical starting point is to have the engine's specifications meticulously checked and improved. This process involves blocking, decking, and planing the engine to tighter tolerances than OEM standards, ensuring superior specifications and clearances.
During assembly, pay close attention to the installation of rods and pistons, adhering strictly to manufacturer specifications. Properly applying thread-locking compound, torquing fasteners to the correct specifications, and following the recommended sequence are all pivotal steps. These measures collectively determine not only the immediate performance of your engine but also its long-term durability and reliability. Each detail contributes to optimizing engine function and extending its lifespan.
Forged piston clearance: Forged pistons are suggested to run with a piston to wall clearance .002”-.008”
Rod bearings: Buy new set. Don’t use old set. Taking the time to properly measure specs and gaps for proper oil passage is crucial. I seen so many engine builders not take the time to do this properly. Making sure all rod bearings are with in specs.
If not properly specs not followed, this happens:
Proper install on oil squirters: they are not pushed off to the side. Again taking time to place these so they can help cool the cylinder under heavy loads. Check for proper clearance by rotating the crankshaft.
Crankshaft: you can have your crankshaft polished. Its a nice feature because its the main piece that needs to be smooth as possible. Having it balanced out at a higher standard then OEM will help with all other supporting parts wearing properly.
Other optional supporting mods: Upgrading (turbos some of options to choose from), my exhaust manifold, intercooler, air intake, TB, zL1 fuel pump, meth, Gibbs speed 6 port, Nostrum injectors/ Nostrum hpfp upgrades, zzp added fueling kit, manual boost controller, wastegate, (springs choices based of boost you want) differential gearing or open to a LSD, a good catch can like Tracy Lewis catch can is great for helping catch blow by oil. Injectors from OEM ac delco and Bosh are the two are used on this platform. Bosh holds up better to E85 then Ac delco. Get the Bosh if you have Ac delco on your car.
Spark plug gaps: must include these as well. Their a chart based on the lbs of boost your making to properly have your spark plugs set at. I run mine at .026 mm. Because I run 21-26 lbs boost. Reason s because the more boost/ air in the cylinder the highly likely the spark will not blow out. So, I gapped them closer, so that doesn’t happen. Most common is .028-.032 gap works for majority cars running 20lbs of boost.
