The Devastator

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 heard from anyone who has any real world experience with these large engines. Thanks for your help.

SeanW

You will probably have more luck on speedtalk.com

http://www.speedtalk.com/forum/viewforum.php?f=1

The Devastator

Thanks.

AlkyIROC

You're going to need to build that with a tall deck block. That means custom made headers to fit into a third gen.

540-565 with a short deck is common and easy. Increasing the stroke to 4-3/8" can push a short deck to 556-582. Using an aftermarket block, it's common to overbore it from 4.500" to 4.600". Going more than 4-3/8" stroke requires a tall deck block.

Dropping in a short deck block is the same as doing any other BBC swap (454 etc)

Using a tall deck block, the 572 is common but still small by modern standards. Now a 632 is the block of choice. Standard heads have a hard time feeding these big engines. Normally a spreadport head is used. Big Chiefs etc. Going bigger than that and you need to use a 5" bore spacing block, spreadport heads etc.

It's probably better and cheaper to just buy a big engine. I think they'll have a starting price around $50,000.

Orr89RocZ

iTrader: (20)

What are the goals for this motor? Turbo on a 598 should be looking for 2000hp

The Devastator

The bottom end is an assembled short block from PBM. 4.600 bore with 4.5 in stroke. I can't remember if its a tall deck block or not. I don't believe it was. It is a pre-clearanced aftermarket 4 bolt splayed block.

The engine has no real goal. More of an experiment to see what we can make with this engine. My father is a professional engine builder and has never built one this large. Our main concern is that we have no experience with heads on such a large engine. We don't know what works and I was looking for some honest input on head intake runner sizes versus rpm range on motors this large.

We want to run a solid roller cam with ls firing order and a power band between four and 6 thousand rpm. Once its done its going in my 92 camaro and will see mostly pretty light street duty.

We intend to use it to get his name out in the local area. Light drag racing here and there but nothing really serious.

Orr89RocZ

iTrader: (20)

Well just a guess, i'd think something in the 340-360cc range should do that powerband. AFR has some 345cc-357cc heads that are advertised to work well with well over 500 cubic inch motors for up to 7000-8000 rpm and you will be well under that.

Not limited to AFR its just the head that I used for my small blocks and i was looking at their big block offerings. Brodix has good heads too for the big blocks.

If you put a turbo on it, it doesnt need alot of cc's to get flow, the pressured charge will make the power.

87TA on here has a 498 with afr 325 heads and he has run mid 9's in a 82 camaro, low 9.0's in a vega. Think he shifts 7500rpm, so a 345 head should be ok for a 6K rpm turbo 598

But you will be able to make close to 550-600whp on motor alone with any healthy solid roller and big set of heads. You add 15 psi to that and your near 1200whp. Thats on a mild setup.

The Devastator

Thats the info I got over on speed talk. Something like 345 cc intake runners. I was hoping I didnt need huge exotic heads to feed it.

I talked to my engine builder again and he says that the combo uses 6.535 in connecting rods so its definately a tall deck (10.2 in) block.

Dart has some pro 1 heads for about 980 ea bare that have 122 cc combustion chambers and 345 cc intake runners. I sent their tech people an email to ask if they are compatible with a 4.600 bore. Now me and the old man need to decide if we want to run 18 degree heads or not.

The cam is gonna be a special order peice with a ls1 firing order.

Orr89RocZ

iTrader: (20)

Any reason for the LS1 firing order?

This is an interesting setup thats for sure. Please keep us updated on it.

My next build I want to do a twin turbo big block setup and shoot for 1300-1400ish whp. Not sure when that will be.

The Devastator

I did a little research on it and spoke with my engine builder and this is what he said. According to comp cams its usually good for about 15-20 hp on a 400+ inch small block. Its spreads out the load more evenly on the five crankshaft main journals and smooths out the engine at higher rpm. With the normal firing order there is more load on two of the main journals than the other three. Fixing this is supposed the help with crankshaft life and how much torque the crank can handle. This is why ford went to that firing order and chevrolet finally followed suit with the LS family of engines. A lot of guys have been running the 4-7 swap on their cams for a long time. I have only good things about it. Not that many people are doing the 4-7 and 5-3 (LS/Ford firing order) in gen 1 small blocks and big blocks. Again its just what I've heard. My father is a registered engine builder so whichever brand of cylinder head I go with depends on what brands his supplier carries. This way we get the heads at warehouse direct price instead of retail. It usually knocks about 30 percent off the price. Hopefully I can get the bottom end together for around 7k. You'd be amazed how much engine parts are marked up once you see a confidential wd price sheet.

AlkyIROC

If a 4/7 swap cam core was the same price as a regular core, I'd do the swap. The increased cost of a swap cam isn't worth the minimal gains. If you want a custom cam, contact www.bulletcams.com

If you're determined to build a big engine, don't even consider a conventional head. Go right to Big Chief type heads.

I run highly modified Dart 360 heads on my 540. If I unbolt the heads and put them both on a table, you'll be looking at around $5000 worth of heads from all the work that's been done to them and the parts that are in them. I could bump up the price at least another $1000 by having titanium intake valves installed.

Orr89RocZ

iTrader: (20)

I just dont know if you need huge money heads for a turbo motor of this size while attempting to make it streetable. Getting a proper sized single turbo for this car to work well is one challenge, let alone driving it on the street... I think your basic bbc head will be up to the challenge for this motor build when boost is applied. Thats gonna make ridiculous power at moderate boost levels, I dont think high end heads are worth it at this level. N/a motors really benefit from it, but a weekend warrior turbo motor doesnt really need the exotic top end to make power

I know you are looking to see what it will make so if you can spend the cash get the best you can. I'd look into making it a twin turbo setup to get a better range of turbo for that big motor. Twin 88's is all the rage for a big block and capable of near 3000hp. What more can you ask for? lol

The Devastator

I spoke with some of the guys over on speed talk and the consensus was that with two turbos and about 330-345 cc heads would work well in a 4-6000 rpm powerband with this size engine.


I am saving alot of money because my father gets his parts at warehouse direct price(about 30% off). He is also doing all the machine work so I don't have to pay for that.

Is your engine naturally aspirated? What kind of fuel are you running and what is your rpm range/ application? I'm assuming your 540 is a competition level build.

Ultimately I just want to make over 1000 horsepower at the flywheel. Which from what I hear is a VERY modest goal from a turbocharged intercooled engine this large.

Orr89RocZ

iTrader: (20)

It is man, 1000 is cake. I think my 401 small block with these small twins is capable of that much. I've done almost 700 at the tire on a mustang dyno with a way overstalled loose converter so I'm sure its much higher than that with a proper tightened converter. Assuming a 20% loss thats 875 hp at 700whp. Not to far away, just few more pounds boost and better tune.

A couple of S480's on that motor should easily do it. S400 stuff is pretty cheap too. Spool should be good, they come with 80mm compressor wheel I believe (some are 75mm which may be perfect for that goal and rpm range), 1.32 a/r would be doable on that setup although i think its abit large. 1.10 or so would be better.. T6 flange so plenty of airflow going in, no restrictions there. They are fairly large turbos but smaller than a HUGE single.

Figure its a 300 inch motor per bank and needs to make 400ish whp per side. Dont need much turbo for that, 70mm wheels flow more than enough, just need the turbine side large enough to pass the airflow. I'm curious if T4 70mm stuff would be ok for that setup and power level with a .96 a/r. 3" downpipes should be large enough.

S400 stuff uses 4" i believe but you can neck that down if needed.

AlkyIROC

Naturally aspirated drag race engine with two 4.1" flying toilets on a tunnel ram running alcohol. My rpm limitation right now is my cam grind. I currently shift my powerglide at 7500 rpm and cross the traps at 7500. The heads want the engine to go higher. I should use a cam that builds power to around 8000. I haven't decided to do a cam swap this winter or not. Current cam is a Comp Cam 11-740-9. Estimated power is around 850 HP but I've never had it on a dyno. That's calculated from 1/4 mile MPH and the race weight then put through a dyno correction formula based on the current weather conditions. At the high altitude, the engine only makes around 750 HP.

The Devastator

Wow two flying toilets! Back in the 80s my dad used to build alot of alchohol 430+ cu in small blocks for unlimited modified dirt cars. A lot of guys including him ran flying toilets on those motors. He used to turn those things to 9500! I figured your setup was a pretty high rpm piece from what you were saying earlier. Thats gotta be a wild ride. What have you got it in?

AlkyIROC

As in dollar value? I'm guessing the engine is worth around $20,000. An estimated value of the whole car should be around $40,000 but I'd never get that if I ever tried to sell it. I've probably spent far more than that in the 10+ years I've owned it. Changed a lot of stuff, broken a lot of stuff.

As for information about the car, just go to my web site www.hardtail.com The URL is in all my sig files.

You don't make much more HP with dual toilets but it sure flattens out the power curve. Each toilet is 1800 CFM so that's 3600 CFM induction. To compare the size of the toilet to a typical throttle body, 4.1" is a 104.1 mm throttle body and I have 2 of them feeding a 540.

The smallest Enderle hat system is a bug catcher and it's rated somewhere just over 3000 CFM. They've been mounted on SBC engines. The bird catcher and buzzard catcher are even bigger.

The CFM rating of an injection system isn't the same as the CFM rating of a carb. It's just a throttle body to allow air into the engine but the effect is the same. Adding more air into the engine allows it to breath better and will flatten out the power curve. With too big a carb, you run into other issues of trying to get the fuel out of the carb. Injection systems don't have this problem.

The Devastator

Did you run your car at the southern midsummer nationals in Tennesee last year? I swear I saw I remember seeing a car just like that one.