BLOCK AND HEAD

NZ Performance Car - - Weekend Workshop -

First off, you need to de­cide what head you are go­ing to run, the P11 or the P12.

You need to think about the bot­tom end you will use, and if it’s up to the task of the turbo/cam set-up you plan to have. If you use fac­tory DET pis­tons, you are limited with your cam choice — the pis­tons don’t have notches for valve clear­ance as a set of af­ter­mar­ket CP pis­tons does, like those pic­tured. The ex­treme lift on th­ese VE cams is no joke.

The oil pump from your DE/DET en­gine is not ideal to use with the VE head. Although there are no fit­ting is­sues, the DE/DET pump doesn’t pro­vide enough of a con­sis­tent high oil pres­sure, which is needed in a VE en­gine, so a VE oil pump and front cover should be used. That means the crank pul­ley needs to have 3mm ma­chined off the rear and a VE oil pump spacer/pump driver needs to be used, as it is longer.

The head oil drain at the rear of the block on the SR20DET en­gine needs to be blocked up, and there are a few com­mon meth­ods to do this: ham­mer in a bung (one which doesn’t pro­trude over the block height), weld up the hole and have the block decked and smoothed, or drill and tap the hole and screw in a suit­able bung.

Be­cause the head is al­ready off, you will need to re­place the head gas­ket be­fore the head goes on. DET head gas­kets aren’t suit­able for this ap­pli­ca­tion, but VET items are. A fac­tory-rated SR20VET head gas­ket will only cost you around $80 through Pten, and they’re strong enough for 447kW (600hp). If you are hunt­ing power and want some se­ri­ous se­cu­rity, by far the best op­tion is the range of head gas­kets from Cos­worth. They’re multi-lay­ered steel and come in a range of thick­nesses — 1.1mm, 1.5mm, and 1.8mm.

The valves and valve springs will need to be re­placed if you plan to use the en­gine for rac­ing, or con­stant high-rpm abuse. The fac­tory ex­haust valves can’t han­dle rac­ing heat con­di­tions, so they can be a weak point.

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