I am a big fan of ls1 engines and the potential they have. Some get by with 500rwhp out of their 346 N/A combinations.
The ls1 platform is great, because GM kept exploring it past the Ford pushrod days in the early 90's.
The ls1 346 (not 350
) has a 3.62" stroke and a 3.90" bore, which aims more of a square design than a 347 stroker of 3.4" stroke and a 4.030" bore.
The ls1 features a 200cc runner volume head, with 2.00" valves on the intake and 1.55" on the exhaust.
Those head ports are also a taller design, which also allows for a better fuel injector placement sprays the fuel on top of the intake valve, while a 302 design sprays it near the end of the lower intake runner ports.
Also the ls1 heads have 15* valves, compared to 20* valves of a standard 302 design. A shallower valve angle (15*) becomes less "shrouded" by the cylinder wall with that angle approach. It also puts the intake valve closer to the piston center, which in turn allows for a larger intake valve, i.e., 2.00" on the intake side.
The ls1 heads also come with 8mm valvestems and lighter valvetrain, as opposed to a 302's standard size of 8.73mm valvestems. The ls6 heads are even better, down to sodium filled exhaust valves
Airflow Chart for stock LS1 Heads:
Lift Value (in.) - Intake Flow - Exhaust Flow
Inches - CFM - CFM
0.100 - 067 - 052
0.200 - 122 - 097
0.300 - 178 - 133
0.400 - 215 - 156
0.500 - 219 - 170
0.550 - 223 - 176
0.600 - 227 - 180
As you can see, the stock aluminum ls1 heads flow quite close to an AFR 165cc head from the mustang world, just losing a little bit in the exhaust portion (AFR > LS1).
The ls1 block is a 4 bolt aluminum block with a 9.24" deck height as opposed to the 302's deck height of 8.20."
The pistons coupled with the 67cc chamber is already getting the ls1 to around 10:1 compression, because after all more stroke, coupled with a taller deck height helps compression ability.
Back up top, you have a plastic composite intake (much like the 4.6L) with a 15" runner, and 536 cubic centimeters of volume, which all makes up the cross section.
The cam specs are smaller in "our circle," as stated. But, they are billet steel and a larger base circle cam (larger lobe area) from the factory, which is great for stability at high rpms with some 1.70" roller rockers sitting on top of the heads.
1998 - 2000 LS1
202*/210* Int/Exh @ 0.050" Duration, 0.496" / 0.496" Lift, with a wide Lobe Seperation Angle of 116*. That gives it a broad torque curve.
2001-2002 LS1
2001 - 2002 Fbody
197*/207* Int/Exh @ 0.050" Duration, 0.467" / 0.479" Lift with that same LSA of 116*.
With larger flowing heads, you do not need a "larger" camshaft.
Large Heads = Small Cam
Small Heads = Large Cam
These are generality's but remain quite true in most circles of designing a combination.
This just helps us see what "we" are up against
It is not to hard to see why a nice longtube swap, coupled with a camshaft swap, can put these ls1 platforms well over 400rwhp.
There is not much room for stroking the engins to much, without getting another block with longer cylinder skirts, or sleeving the existing block for a little more room to play with.
The ls1 pushrod is a beast for OEM, but the modular engine line has it's pros as well
An overhead engine, like the 4.6L engines, allows lighter valvetrain weight and mass which is great for increasing hp/tq per Liter of engine size.
A 4.6L pushrod would make less horsepower per liter than a 4.6L OHC (Single or Dual). Also, Ford knew that going overhead cam was the best way to be on the heels of cutting edge. Putting the cam "on top" allows them to use, 4 valves per cylinder like in the DOHC engines that came in the '96-04 Cobras
Greater rpm potential and stability. The only expense that I see with going this route is increased size needed. Although the engine weights are similar between the 5.0L pushrod and 4.6L SOHC/DOHC.
The 4.6L intake weighs 11 lbs from the one I weighed, while 5.0L intakes weigh in the 40-low 50 pound range. A single head is 43 pounds WITH a camshaft and full valvetrain, because they are aluminum.
They all got potential to make great power per cube.
However, there is no replacement for displacement until you start talking poweradders
