We had a very pleased Tony Mamo from AFR cylinder heads in the US contact Doug in our Mississippi branch the other day after he had finished testing the YT Ultralite LS1 rockers on his latest project engine.
Tony said.
Here's a quick rundown of the parts (and a few extra machining op's) which helped us achieve the numbers we did...
LS2 Block honed .005 oversize with TQ plate and ARP head studs (hence the 403 CID displacment....not a 402)
Premium rotating assembly which consisted of a Dragon Slayer Callies Crank, Callies Comp Star rods, and Diamond pistons (which were also hard-coated as well).
ATI Harmonic Balancer
Painstaking time spent on shortblock clearances including bearings, piston to wall, ring end gaps, cylinder wall finish, etc., etc. I bring this up because it will have an outcome on the total power produced.
Static CR was kept at only 11.25 to 1 with a quench distance of .031 (pistons .010 out of the hole.....041 thick Felpro Head gaskets).
Ported GM Hi Perf Oil pump
Comp Custom ground cam 232 / 232 on a 114 LSA +1 (113 ICL)
GM Cadillac Racing lifters set to .100 pre-load.
AFR 205 Heads with reworked chambers to take advantage of the larger bore and light porting on intake and exhaust (minimal increase in cross section). Killer "area under the curve" gains with the mods performed allowing alot more average air to enter the cylinder on each gulp....especially useful at higher RPM's when the engine has only a tiny fraction of a second to fill the cylinders....none of the airspeed was reduced, in fact increased due to all the additional airflow passing thru essentially the same size hole....a very lethal combination. I have included the actual flow number down below the dyno charts.
FAST 90 ported as well as a ported NW billet TB
Yella Terra "Ultra-lite" shaft rockers 1.7 ratio
QTP 1.75 headers which made the same power and ten more ft/lbs of TQ over a conventional dyno header at 3000 RPM's.
She ended up making just on 600hp and turned clean to 6100rpm.
here's a link to Doug's blog with the video.
http://www.dsmithz28.com/
Cheers.
Mark.
LS1/2 Ultralite rocker testing
Linear Mode
