600+HP with a FT cam, 355 cubes & OEM iron heads
Posted: Mon Feb 11, 2019 5:49 pm
This one belongs to a good friend of mine, I've been looking after this thing for about 13 years.
In it's previous life it was a well know burnout car (VK commodore), turning 8600-8800rpm for 2 minutes at a time with a dry sump.
Those days are over now & it's moved to drag racing.
Last time out it ran a best of 10.27 @ 131mph @ about 3200lb.
The owner builds the motor, I take care of machining, headwork & cam specs etc.
It was time for a power up with the aim of getting into the 9's in a full weight VK calais, bottom end is pretty fresh so we left it alone, just pulled the heads, stepped up from 2.02 to 2.055" intake valves, did some more porting, ported the intake to suit, stepped up the cam & modified the headers.
Specs are pretty simple, it's a 355 cube holden with factory VN iron heads:
Stock block, M&W 4 bolt main caps on the centre 3, stock on the ends, grout fill, heavily modified oiling system (left over from it's burnout days).
Harrop cast crank (same crank has been in the motor all these years, still hasn't been ground), Scat H beam rods, CP true flat top pistons (no valve reliefs).
ASR competition oil pan with external pickup.
Moroso external belt driven pump
Moroso 3 vane vac pump
VN iron heads with a big, but not maxxed out port job, 2.055/1.6" valves
Harrop intake, match ported, plenum & runner entry work with a 1" open spacer attatched & runners raised into the spacer, mid section on the runners is as cast.
Yella terra platinum shaft rockers, PAC springs, manley TS retainers, rollmaster timing kit.
Custom ground solid flat tappet cam to my specs by Camtech - 267/274 on 108 centres, .630/.580" valve lift with 1.65 rockers.
Quickfuel 850 methanol carb, MSD distributor & ignition, MSD crank trigger
13.5:1 compression
Had a couple of little issues on the dyno, we didn't open up the short & I had forgotten we had a lip seal in the rear main, so we could only pull 4" of vac before the seal pulled in, with the modified oiling system even at 50% drive on the oil pump pressure was over 80psi at high rpm, winding out the relief only dropped the pressure at lower rpm, relief could not pass enough to regulate pressure above 6000rpm.
Those issues are now fixed with 43% drive for the pump & a rope rear main seal, but it won't be going back on the dyno - those 2 changes & being able to pull 10-12" of vac will be worth at least 10hp.
Motor is going in the car shortly, along with a new 6000rpm converter (up from 4500).
20190117_110141 by tony knight, on Flickr
20190118_084717 by tony knight, on Flickr
In it's previous life it was a well know burnout car (VK commodore), turning 8600-8800rpm for 2 minutes at a time with a dry sump.
Those days are over now & it's moved to drag racing.
Last time out it ran a best of 10.27 @ 131mph @ about 3200lb.
The owner builds the motor, I take care of machining, headwork & cam specs etc.
It was time for a power up with the aim of getting into the 9's in a full weight VK calais, bottom end is pretty fresh so we left it alone, just pulled the heads, stepped up from 2.02 to 2.055" intake valves, did some more porting, ported the intake to suit, stepped up the cam & modified the headers.
Specs are pretty simple, it's a 355 cube holden with factory VN iron heads:
Stock block, M&W 4 bolt main caps on the centre 3, stock on the ends, grout fill, heavily modified oiling system (left over from it's burnout days).
Harrop cast crank (same crank has been in the motor all these years, still hasn't been ground), Scat H beam rods, CP true flat top pistons (no valve reliefs).
ASR competition oil pan with external pickup.
Moroso external belt driven pump
Moroso 3 vane vac pump
VN iron heads with a big, but not maxxed out port job, 2.055/1.6" valves
Harrop intake, match ported, plenum & runner entry work with a 1" open spacer attatched & runners raised into the spacer, mid section on the runners is as cast.
Yella terra platinum shaft rockers, PAC springs, manley TS retainers, rollmaster timing kit.
Custom ground solid flat tappet cam to my specs by Camtech - 267/274 on 108 centres, .630/.580" valve lift with 1.65 rockers.
Quickfuel 850 methanol carb, MSD distributor & ignition, MSD crank trigger
13.5:1 compression
Had a couple of little issues on the dyno, we didn't open up the short & I had forgotten we had a lip seal in the rear main, so we could only pull 4" of vac before the seal pulled in, with the modified oiling system even at 50% drive on the oil pump pressure was over 80psi at high rpm, winding out the relief only dropped the pressure at lower rpm, relief could not pass enough to regulate pressure above 6000rpm.
Those issues are now fixed with 43% drive for the pump & a rope rear main seal, but it won't be going back on the dyno - those 2 changes & being able to pull 10-12" of vac will be worth at least 10hp.
Motor is going in the car shortly, along with a new 6000rpm converter (up from 4500).
20190117_110141 by tony knight, on Flickr
20190118_084717 by tony knight, on Flickr