bill jones wrote:-have you done anything to the heads? changed cams, valves etc or is it a stock internal engine?
Eagle H beams, custom Ross pistons, some mild head work. On the heads about the only reason we go +1mm is to be able cut a decent seat profile.
If you want Ferrea quality at a lower price look into Supertech for valves.
Not a lot of science in the ports, just basic cleanup. The intakes flow in the 280-300 CFM range @ 28"/H2O at .400-.450" lift, exhausts 240-260. Valves are 34mm intake, 30.5 exhaust. It just isn't cost effective to spend a bunch of time in the head when you can just crank the boost and slap a bigger turbo on it.
Intake manifold is a sheet metal unit, total runner length is ~ 8". Intake manifolding is pretty much an open market on these things, the ones on the market are crude and simple with very little real development. They all improve upper RPM power, but there are no real gems out there.
The cams are hydraulic end pivot rocker, .415/.400" lift and seat timing is 259/258 on 108/114 lobe centers.
I do spend a lot of time on the chambers because the factory castings have a buttload of shrinkage towards the outer cylinders and the chambers are offset a bit and very inconsistant.
No coatings. I'm not convinced thermal coatings help much after the base layer of carbon gets built up. I would like to do the exhaust ports, chambers and see if it helps on the very high HP apps where the head folds up like a potato chip under the exhaust port and blows the head gasket in 2 runs.
This particular engine showed some signs of 'magic', where it usually takes an NGK 8 or 9 heat range plug, this one wants 7's and has very little signs of knock activity.
FYI the timing it likes on pump gas at full load is 10 deg ramping up to 13 after 6000, and I usually run them in the 11.5:1 AFR range for pump gas at full boost. This one will tolerate 13:1 but it ain't worth the extra 10 HP.
Boost controller was not allowing full boost till 6000, should have full torque at 4500, and it drops 2 PSI from 6000-7000.