Don Terrill’s Speed-Talk

I am in the the process of getting a shortblock for a 598 cu inch Big Block Chevy. I have little experience with these HUGE big blocks. I was hoping to get some input from people who have run 572 cu inch or larger big blocks.

I've been looking at Aluminum heads and figured I would need intake runners sized around 400 cc to acommodate what I want to do. I intend to build my 598 to make power between 4 to 6 thousand rpm with DFI and a solid roller cam and one turbo on pump gas.

I would love to hear from anyone who has any real world experience with these large engines. Thanks for your help.

I don't do single turbo engines in that range, and don't know if this is a power engine, or all out kinda deal. Also, is it in the drag race world or endurance application. And the pump gas thing makes me think more endurance, and not all out. (So take that for what it is worth.) but 400 seems way too big for your application. The thing is gonna be a friggin' pig at lower rpm's and before the thing starts to spool. For a 600 inch drag race engine that wants to run 6000-8000 I would be looking for a good designed head in the 360 + range. Something that wants to run in the 4000-6000 I would want something much smaller. Now as for the turbo side of things, I usually run two smaller turbos on sizes that big, and keep the boost at 10-15 for endurance applications, but even then, I look for a much smaller runner.
Now, here I am making assumptions that this is a street/strip deal or something that needs part throttle and great power, but not an all out drag race kinda thing. So again, take this for what it is worth. I would be looking for something as cast in the 350-360 range, or something that flows big numbers/ported/cnc'd or whatever in the 340 range.

It will be a street strip engine that wont see much drag racing. Aiming for a 9.0:1 compression and 4-6k power band. I want a higher power band because I don't need mega crusher torque off idle in a street car with 10 inch wide tires. I also don't intend to run more that 12 pounds of boost pressure when I'm drag racing and I'll probably run 7-9 on the street. I want to retain a lot of reliability, hence the displacement. I could have made just as much power as I want on a 496 and turbos but I want to keep it as simple and reliable as possible. I will look at those heads in the 320 to 340 range. Thanks alot for your input. I appreciate it.

Knowing what you said about your application, I would look for a good designed (maybe ported) and well flowing 320 or a good as cast 340 or 345ish.
We had a similar one with twin turbos recently and put iron heads on it for the durability, and went with a 320 and did some work with it and it outperforms what I had thought in my wildest dreams.

I'm doing a 555 with a friend right now that will run twins on pump gas but we're still starting out with fairly small heads. Pro filer 320's are the base and they will probably end up about 345-350cc. Plenty to make 1000 at the wheels and be very driveable with around a 272@ .050 cam and 9:1

Thanks alot guys this info helps me tremendously. I was afraid I was gonna need huge exotic heads, but several mfr's produce 320-345 cc aluminum heads for relatively cheap.

Do you guys think I should run cast iron heads on this rig? I don't ever intend to run more than 12 psi on this rig. The engine is going in a 92 camaro and I don't want to have to run down heavier springs for my front end if I don't have to.

12psi on that motor shouldnt be asking for much. 320-340cc head that flows thats darn near 1000whp on just 12 psi. Thats an easy pump gas street combo. I got about 700whp at 15-16psi with my small 401 small block.

Plenty of guys run aluminum heads on small blocks making that much power. Dont see why you need iron for the big block.

i used Dart Pro 1 cnc 355 heads. 2350hp with twin 88's.
Either those or RFD/Edelbrock 24deg heads.
Good enough for street driving too..

Iron heads are nice for shear durability. My last deal was in a ski race boat. And 50 degree cold water coming into an engine really upsets certain things. But no reason that aluminums would not work just fine for you. And keep 88lb or so off of the front end.

I'm going to be the first to say that a 598 and single turbo don't make the most sense to me. Even the largest 1.5a/r / G trim combination doesn't match up well with that many cubic inches even only spinning 6k. I'd reconsider engine size before I'd figure on which head to put to it. A traditional 520-540" with a mid 330cc head would be much more efficient with a 106/114 than a 598 would be.

I've built multiple 540-572" applications chevy/mopar etc and they're street strip and full race applications. You didn't mention your intercooling plans, therefore I'd consider running an aluminum head to keep chamber temps in order.

Its not much more expensive to run dual turbos. If one won't feed that many inches then I will run two. I'm gonna run one of those new sts turbo setups with a water to air intercooler. They supposedly have the lowest charge temps around.

The main reason I want to run aluminum heads if for weight. I just had a concern about durability on turbo/supercharged application. I usually prefer cast iron heads but I want to retain the factory style springs in the front of my camaro. The weight of a big block with aluminum heads is supposed to be inline with a L98 TPI 350 small block.

Thanks again for everybody's input.

If it was me I'd go with the cast iron heads. They will hold the gasket better for a longer time. I don't think all that heat cycling that you will see is good for the alum heads, don't get me wrong, alum will work well, but I like the idea of a more rigid deck. Don't forget to plump some water out of the back of the heads or manifold as you will have siamese cyls. and it will trap some air if you don't. good luck!!!