600+HP with a FT cam, 355 cubes & OEM iron heads

General engine tech -- Drag Racing to Circle Track

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KnightEngines
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600+HP with a FT cam, 355 cubes & OEM iron heads

Post by KnightEngines » 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).



Image20190117_110141 by tony knight, on Flickr

Image20190118_084717 by tony knight, on Flickr

KnightEngines
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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by KnightEngines » Mon Feb 11, 2019 5:51 pm

Power with the vac sorted & pump drive reduced *should* be in the region of 625hp.

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by Newold1 » Mon Feb 11, 2019 6:06 pm

You Aussie's get some great results out of those Holden engines. Even 85000-8800 rpms for two minutes is a great accomplishment, with a cast crankshaft!

Question, what do you think the HP at what rpms was in the original build versus the 625HP you are pretty confident of now.
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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by KnightEngines » Mon Feb 11, 2019 6:20 pm

We never dyno'd it previously, but best guess it was making around 560-580hp in the low 7000rpm range, it was showing 550 moroso HP to the track - which was probably a bit lower than it should have been due to the 4500rpm converter & lacklustre 60' (was in the 1.5s range).

I love the old holdens, power achievable with factory heads is better than anything else made before 2000.

A couple of weeks ago we dyno'd a 383 cube holden pure street engine, with factory 1.94/1.6" valves & basic pocket port & cleanup, 230/234 on 110 hyd roller cam, low rise intake, 10.5: compression & tri-y headers it made 485hp @ 5800rpm & gobs of torque.
Try that with a OEM head chev!

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by Newold1 » Mon Feb 11, 2019 6:38 pm

Pretty great results there mate! =D>

I think that extra 60-70HP and some more rpms with that new converter should probably get that same car into the 9"s.

Best of luck on the results!
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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by tuffxf » Mon Feb 11, 2019 6:45 pm

Awesome Tony,
Very impressive!
Cheers

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by paulzig » Mon Feb 11, 2019 7:47 pm

KnightEngines wrote:
Mon Feb 11, 2019 6:20 pm

Try that with a OEM head chev!
There is a 383 on here with the stock small port vortec heads that did that and a bit more.. Guess you could class them as OEM..

Its one of Randy's ...

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by KnightEngines » Mon Feb 11, 2019 7:53 pm

Bit more than a pocket port & cleanup tho! The SN 383 is an impressive piece tho.

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by paulzig » Mon Feb 11, 2019 10:52 pm

KnightEngines wrote:
Mon Feb 11, 2019 7:53 pm
Bit more than a pocket port & cleanup tho! The SN 383 is an impressive piece tho.
The SN is a 355, the other one is his pseudo racing 383 heads are stock...

viewtopic.php?t=42988

"GMPP small port vortec bowtie heads just as GM sent them with 2" intake/ 1.56" ex manley valves"

I take just as GM sent them means unported and stock...

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by steve cowan » Tue Feb 12, 2019 1:56 am

good job as per usual Tony,
i am trying a set of tri-y for my combo after this weekend,can you recommend a collector length that you see that works on the dyno.
383 sbc,180cc head,SFT cam 235-242,500''lift,106 lsa,ICL 104,
10.5:1 comp ,air gap manifold,750 carb.car ran 114 mph @ 3650 pounds in 36 deg C heat last weekend. 6200 - 6500rpm max
i ordered a set of GENIE tri-y 1 5/8'' - 2''- 2 1/2'' collector.
the exhaust port on these little Dart heads is small and pretty fast 320 ft/sec with pipe on @ 28'' depression.
any tips appreciated
paulzig wrote:
Mon Feb 11, 2019 10:52 pm
KnightEngines wrote:
Mon Feb 11, 2019 7:53 pm
Bit more than a pocket port & cleanup tho! The SN 383 is an impressive piece tho.
The SN is a 355, the other one is his pseudo racing 383 heads are stock...

viewtopic.php?t=42988

"GMPP small port vortec bowtie heads just as GM sent them with 2" intake/ 1.56" ex manley valves"

I take just as GM sent them means unported and stock...
i have read that and all of Randys threads numerous times,BLOWS ME AWAY that pseudo deal on how much power it does make and time cards to back it up
steve c

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by BlitzA64 » Tue Feb 12, 2019 10:24 am

Sweet build. Love the flat power "curve"

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by MELWAY » Wed Feb 13, 2019 7:29 pm

Compression is king hey TK. Nice outcome

Did you try a oxy racing fuel like MS109 vrs the methanol
At this dyno session? Could be even more power at pk HP
3370lb Sedan 9.89@136MPH 358chevN/A

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by KnightEngines » Wed Feb 13, 2019 9:18 pm

Nah, it'll only ever run on meth, so not a lot of point.
We did discuss it tho, Con reckons roo16 would be worth around 15hp up top.

I'd like to get some more lift into it, .630" intake lift is holding it back, but that can come down the track a bit.

We just need the damn strip to open up again, nfi what's going on there.
The new Tailem strip is still a good 9 months from completion, nearest functional full 1/4 is heathcote - 7 hrs drive away.

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by MELWAY » Wed Feb 13, 2019 9:34 pm

Good stuff Tony. Hopefully catch up with you at heathcote

Drag racing is grim and frustrating for our part of the world
3370lb Sedan 9.89@136MPH 358chevN/A

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Re: 600+HP with a FT cam, 355 cubes & OEM iron heads

Post by Biteme » Thu Feb 14, 2019 2:07 pm

I love threads like this!
That rpm is nuts!
How much valve spring does it take to make a f/t live at 8500+rpm???
Is the cam nitrited?
Super lightweight valves etc?

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