Anyone swapping long blocks on these?
Anyone swapping long blocks on these? Got a guy who wants to put a 6.2 in since the LS4 died. My concerns are intake, trans bolt pattern, and doesn't the LS4 have a slightly shortened crank? Of course the typical conversion growing pains apply, but my main concern is will the trans bolt up and if all the accessories are swapped would there be any clearance issues?
No trans won't bolt up...best cost effective method if your going that route is a standard over bore 9n the ls4 to ls1 bore size, bolt it all together get your intake swap and related upgrades on and you should be at 400whp
Between overheating and oil starvation i don't trust the motor coming out at all as far as reusing it.
The LS4 uses the GM Metric bellhousing pattern and doesn't share any bolt holes or alignment dowel location with the the SBC bellhousing pattern used with the LS(x) RWD engine family.
You can install a RWD LS(X) based engine, but you will need an adapter plate that keeps the crankshaft flange at the same depth into the 4T65e-hd. You will need to use the LS4 flex plate and starter setup as well.
Since the LS4 block is about 3/16" longer (at the bellhousing side to clear the bolts on the rear camshaft cover) and the crankshaft is 3mm shorter on that end, the adapter plate needs to be around 5/16" thick.
One thing to consider, to get a RWD block to clear the 4T65e-hd, you have to cut the RWD starter pad portion of the block off. This will ruin the block from being able to be installed in a typical RWD fashion in the future, so it is something to consider.
Since the backside of the crankshaft is 3mm longer, everything that bolts to the engine would have its position shifted in the engine bay 3mm (.118") to the passenger side. So you may need to slot some engine mount holes, but this isn't much of an offset, so it shouldn't be a deal breaker. Since the engine placement will move, but not the transmission, the exhaust crossover will likely have reduced clearance to the transmission bellhousing flange, same with the down pipe going under the chassis.
On the balancer side, the RWD crankshaft is 10mm (.394") longer. The LS4 crankshaft is recessed slightly (I forget the dimension - around 1/8") in the LS4 balancer, so the critical extra length is around 1/4". The RWD crankshaft will poke through the outer side of the balancer, but you can use a sleeve with 1/4" wall thickness and about 5/16" in length to enable the crankshaft bolt to properly clamp the balancer.
You can install a RWD LS(X) based engine, but you will need an adapter plate that keeps the crankshaft flange at the same depth into the 4T65e-hd. You will need to use the LS4 flex plate and starter setup as well.
Since the LS4 block is about 3/16" longer (at the bellhousing side to clear the bolts on the rear camshaft cover) and the crankshaft is 3mm shorter on that end, the adapter plate needs to be around 5/16" thick.
One thing to consider, to get a RWD block to clear the 4T65e-hd, you have to cut the RWD starter pad portion of the block off. This will ruin the block from being able to be installed in a typical RWD fashion in the future, so it is something to consider.
Since the backside of the crankshaft is 3mm longer, everything that bolts to the engine would have its position shifted in the engine bay 3mm (.118") to the passenger side. So you may need to slot some engine mount holes, but this isn't much of an offset, so it shouldn't be a deal breaker. Since the engine placement will move, but not the transmission, the exhaust crossover will likely have reduced clearance to the transmission bellhousing flange, same with the down pipe going under the chassis.
On the balancer side, the RWD crankshaft is 10mm (.394") longer. The LS4 crankshaft is recessed slightly (I forget the dimension - around 1/8") in the LS4 balancer, so the critical extra length is around 1/4". The RWD crankshaft will poke through the outer side of the balancer, but you can use a sleeve with 1/4" wall thickness and about 5/16" in length to enable the crankshaft bolt to properly clamp the balancer.