While I don't disagree with your points/methods defrag, can I pose a question.

For a VH45 that will see duty under 30+ psi of boost. Would forged pistons and beefed up conrods not then be justified? I have absolutely no experience with the VH motor, but I do have a lot of esperience with high boost 4G63 motors, and as an engineer I understand the mechanical stresses that are put on engines at elevated boost pressures.

I would like to think that Forged lower compression (9.0:1) pistons, aftermarket forged connecting rods, ARP rod bolts, Head Studs, and valvesprings would be more suitable for a life of high boost than a modified combustion chamber and a thicker head gasket.

I've just seen one too many "thick" headgasket fail already that would sway me away from them

Yes, I do plan on building a VH in the very near future and I want to have as much knowledge at my disposal as possible.

I am leaning towards stock overbore pistons + headgasket spacer due to price and the time constraints. I have seen a lot of spacers fail too but because my boost is limited I'm gonna be aiming for the GTIR valvesprings, having the heads checked and repaired if necesary, getting some ARP headstuds and a thicker headgasket, and getting the motor back together.

Also probably going to have to have some adaptors machined to bolt up my intercooler to the intake ports, the Q throttle body to the back of the M112 blower (its got an electronic throttle which is no good for me) so I guess I can get the headgasket spacer made at that point in time (when I'm going bankrupt lol).

anyone got an idea on the price of one of those spacers?

Clifton wrote:To help stir up the pot. To get 450 crank out of a 4.5l will cost much more (cams, head work, pistons) than adding 10 psi to a stock 4.5 and easliy getting 450 HP plus a HUGE bump in torque across the board that an n/a 4.5 couldn't hope to ever see.

Well you go get your head work and pistons changed, I'll stick to my cam grind & basic breathing mods + tuning to get the desired power, as has already been done before.

You may need headwork done, however, nissan was nice enough to do most of the headwork for us!!

SuperHatch wrote:While I don't disagree with your points/methods defrag, can I pose a question.

For a VH45 that will see duty under 30+ psi of boost. Would forged pistons and beefed up conrods not then be justified? I have absolutely no experience with the VH motor, but I do have a lot of esperience with high boost 4G63 motors, and as an engineer I understand the mechanical stresses that are put on engines at elevated boost pressures.

I would like to think that Forged lower compression (9.0:1) pistons, aftermarket forged connecting rods, ARP rod bolts, Head Studs, and valvesprings would be more suitable for a life of high boost than a modified combustion chamber and a thicker head gasket.

I've just seen one too many "thick" headgasket fail already that would sway me away from them

Yes, I do plan on building a VH in the very near future and I want to have as much knowledge at my disposal as possible.

Super,The only reason I'm reccomending he stay with all his stock stuff is because he has a mild power goal with somewhat mild boost levels.On a VH running 30+ psi on anything, or one that is going to be seeing alot of power and high rpm -- forged pistons/rods, ARP fasteners, and stainless or inconel valves are definately a must... not so much valvesprings, except if you are going to exceed stock rev limit or use some new cams.

I used to have a 2g piston/bigrod 6bolt 4g63 with a holset H1C too.. you should do the same mods internally to the vh that people do in the dsm world to prepare an engine for lots of power/rpm (or anything over the 450-ish horsepower mark).

does anyone know a cheap place to get OEM overbore pistons and rings? I checked and the only site I could find them at online had them for $80 per piston/pin and rings were an extra $260.That puts the total at nearly the price of custom forged pistons.

well given the high price of oem pistons, I'm considering flatlander's deal. IPP custom pistons, 75 pounds sterling each, comes out to around $1100 or so- just a hair over factory.