604 Crate Motor modded for road race

[bosco]

I picked up a good, used, disassembled 604 GM crate motor for a very reasonable sum. Thinking of turning it in to a back up motor for my tube frame 1969 Corvette road racer. Here is the plan:

* 3 stage dry sump
* port the fast burn heads
* more aggressive hydraulic roller cam 7 K rpm limit
* SCAT H beam rods with Mahle pistons to make 11 to 1
* 750 Holley HP

Will this combo get me to 500 HP and about 450 torque ?

Thanks for your consideration

[mag2555]

This can't be a real question now is it!

[user-612937456]

Easily you neéd to raise your expectations some

[bosco]

That would be 100 HP and 50 lbs ft of torque over as delivered. I can't see it delivering much more than that, but would be satisfied with that. The primary motor is a 327 with Brodix heads, solid roller, 7500 plus rpm. It makes 525 hp and 420 torque.

[CamKing]

It should get you close to that.
You'll also need to change the valve springs.

[bosco]

thanks Mike

[CamKing]

Easily you neéd to raise your expectations some

With the 7,000 rev-limit, it'll need to make peak HP below 6,600 for road racing. 500hp is about right.

[randy331]

I picked up a good, used, disassembled 604 GM crate motor for a very reasonable sum. Thinking of turning it in to a back up motor for my tube frame 1969 Corvette road racer. Here is the plan:

* 3 stage dry sump
* port the fast burn heads
* more aggressive hydraulic roller cam 7 K rpm limit
* SCAT H beam rods with Mahle pistons to make 11 to 1
* 750 Holley HP

Will this combo get me to 500 HP and about 450 torque ?

Thanks for your consideration

The GMPP fast burn heads are better than most think, and than the flow numbers would suggest.
I've ported several sets of those and they've all made good power.
The seats will only accept a 2.02" valve, so if your changing valves that's all you can go without new seats.
You should be able to make your power goals with a decent port job.

Randy

[bosco]

Thanks Randy, good info. I was gonna leave the valves as I understand they are decent pieces. I am thinking this would be a torquey motor with some good mid range... an easy to drive, budget road race mill.

[DaveMcLain]

The Bowtie intake manifold that comes on that engine is pretty terrible so you might want to try something else and see if you find an improvement.

[Keith Morganstein]

604's make close to 500hp with allowed mods in circle track now. (Some series allow modifications) engines get blueprinted, cam change , rocker arm and valve springs, intakes. No porting but a carefully worked out valve job.

[bosco]

The Bowtie intake manifold that comes on that engine is pretty terrible so you might want to try something else and see if you find an improvement.

I think we have a Victor Jr laying around, if that would be better.

[levisnteeshirt]

The port match for the heads / intake usually stinks , saw where GM has a lifter designed for a cadilac that's supposed to be usable and 8000 rpm compatible, not very expensive either , might be worth a look ,

[In-Tech]

The Bowtie intake manifold that comes on that engine is pretty terrible so you might want to try something else and see if you find an improvement.

Hi Dave, I was on the dyno Friday with one of these engines, unstrapped it and ripped it apart a few hours later. I really didn't pay much attention to that intake except to assume it was a vic jr cast by edelbrock for gm so I guess not. If anyone has any pics they would like to share of a modded one I would appreciate it. New cam is being ground Monday and overnighted. I'm trying to be back on the dyno Wednesday.

[In-Tech]

604's make close to 500hp with allowed mods in circle track now. (Some series allow modifications) engines get blueprinted, cam change , rocker arm and valve springs, intakes. No porting but a carefully worked out valve job.

I believe that's about what we are allowed too. I better check to make sure I can port this intake.