Filled block (torque capacity)

[toddshotrods]

This is in reference to a SBC.

I am planning to use Hard Block Water Jacket Filler, to build a progressive nitrous motor. Just wondering how much torque has been made with a filled SBC before Scotty screams, "she's breaking up!"



The block is a four-bolt 350, and I am planning to building a 355. Plan is for: 4340 forged crank, H-beam rods, nitrous pistons, custom grind cam, aluminum heads with nitrous specific port and valve work, full roller valvetrain, single plane with EFI, etc.

[graycamaro]

How much power do you plan on making on nitrous? Is this to be a street motor or drag only? I would recomend you have a 2bolt block set up for 4bolt splayed caps and use head and main studs and you shoud be good to go with out filling the block. Generally the block itself is not the weak link unless you get really rediculous with power like over 1200hp or something.

[toddshotrods]

It really depends on the weight of the car, but should end up in the 800-1000hp range.

The car will be street driven (on the motor) mostly and sprayed at the strip for grudge racing. I don't plan to beating on it mercilessly every opportunity I get, but when the situation arises I will dump a full 100% shot on it (progressive controller + extreme race kit). I will probably also spray a smaller shot on it at road race tracks (straightaways of course).

I am going to run studs, and will probably end up with the splayed caps, but I am definitely going to fill the block. Besides increasing the torque handling capacity of the block, it will reduce distortion in the cylinder walls. With the amount of nitrous I will be spraying it's cheap insurance.

Locally, I know if a drag racer who has been spinning a filled, 600hp, 355 to 9K season after season without fail; and a former dirt track engine builder who told me he made 675 lb-ft with a filled SBC successfully. I just like to get as much info as possible. Thanks for adding to my "collection".

[Matt@RFR]

Hey Todd! We haven't spoken in awhile, how are things?

I understand budgets, but just for your information, you wouldn't have to worry about any of this with a good aftermarket block.

[graycamaro]

I am just saying that at that power level cylinder distortion shouldn't really be a problem if you didn't fill the block. But I understand if you want the extra insurance just remember you lose some cooling ability and gain some weight at the wrong end of the car when you do this.

[toddshotrods]

Hey Matt! We haven't spoken in a while huh? Time really flies! Everything is great here, trying to turn the corner in business and every time I think I am getting close to wrapping things up with the former stuff - there's more to do!

How are things with you?

I do plan to go with an aftermarket block eventually, but right now those thousands will really come in handy elsewhere in the car. What's that word you used? Yeah, budget that's it ;) ! Biggest problem is that if I spend the money I want aluminum. My friend has a Dart block (SBC) and it's supposed to be good for something like 2000hp, but it also comes with a little extra weight.

Where I live there is not a lot of heavy traffic and always a nearly empty route to get where you're going, so I am not too concerned about the cooling issue. The drag racer I mentioned has had his filled block on the street before and says he didn't have any cooling issues with it around here. The short fill Hard Blok mix is only 12.5lbs so I while I will be adding some weight to the front, it won't be anything ridiculous. With the amount of fiberglass and carbon fiber I am putting in the car I think the car's weight distribution is going to be pretty impressive. I am taking a LOT of weight off the front end.

[myclone]

No cooling issues so far when filling small blocks up to the bottom of the freeze plug. Prolly doesnt add nearly as much rigidity as filling the whole water jacket but these are street motors so keeping the water jacket was a must.

Anyways, some splayed four bolts, filled block to bottom of the freeze plugs, the rest of the fasteners of the correct size/quality, and IMO you'll be safe to 1k ft/lbs in a moderate to light weight car with slicks.

My .02

[toddshotrods]

Thanks myclone. 1000lb-ft eh?!?!? I like that kind of opinion :D

In all seriousness, I appreciate all comments. I make note of them all, positive or negative because someday that knowledge may come in handy. It looks like I am set to build my little bottle baby.

[SatisTraction]

the 4 bolt main is your weak point. The 4 bolt removes too much material from the block and you will eventually drop the crank out the bottom. a 2 bolt main is a much better choice. I have some pics of a 4 bolt that a buddy built. the whole main came out like a slice of pizza!!! the good news is that the crank was not hurt!!

[myclone]

the 4 bolt main is your weak point. The 4 bolt removes too much material from the block and you will eventually drop the crank out the bottom. a 2 bolt main is a much better choice. I have some pics of a 4 bolt that a buddy built. the whole main came out like a slice of pizza!!! the good news is that the crank was not hurt!!

I agree with the above for factory non splayed type four bolt blocks but with a splayed four bolt coversion the meaty part of the main web isnt weakened nearly as much. The outter bolts on a splayed set up end up being mostly out next to the oil pan rail.


toddshotrods,

Just keep in mind that "safe to 1k ft/lbs" is a pretty broad statement and requires EVERYTHING to be top notch from the machine work to assembly to having the block sonic checked to make sure there is enough meat in the casting to withstand some abuse.

Also, be aware that there is no guarentee that a production block wont scatter all over the dyno room at even 700ft/lbs. For piece of mind that the block will hold togeather you need a bowtie block or any number of aftermarket blocks that have beefier castings that the production piece. My point is that there are ppl out there making well in excess of 1kft/lbs with production blocks but they are well aware that at any minute the crank can fall out of the bottom but they are willing to take the risk either for bragging rights or to save a few $$$ (saving a few bucks on a block only for it to go off like a bomb ruining all those high dollar internals still puzzles me but whadda I know ).

Lastly, if we can get a production thin walled 4.3 V6 block with program engineering splayed mains to hold togeather at the 1200+ft/lb level for multiple dyno flogs then a SBC should approach the 1k ft/lb level with less stress.

My .02 FWIW.

[toddshotrods]

Yup, I realize the risks and the need for everything to be top notch. If my wallet gets heavy enough in time I'll just buy the baddest, strongest, aluminum aftermarket currently available. If not, I'll stick the money in the components and machine work - and hope for the best.

Actually you bring up a good point about the need for the machine work to be top notch. Around here I am so used to seeing guys buy good parts and then finding the cheapest guy they can to machine the block or put it together. Even when the motors come apart they won't admit that maybe their machinist/builder isn't all he claims to be. Another thing I see a lot is local builders who never bother to inform the customer that the truckload of engine parts they dumped on their floor won't deliver the desired results when assembled (no matter who assembles them) - because they are a bad combination.

Example: My friend has a 434 SBC and his "star" engine builder never bothered to tell him that his unported Brodix Track 1 heads will never deliver enough oxygen to see the motor's full potential. I think he figured the guy is 68 and will never really use it anyway. To his credit the motor is put together very well, and has held up very well over two seasons - just won't get out of its own way!

I like to go to the end-users with real world experience first.

[ProdigyCustoms]

OK, This is something I know a bit about As I run a couple filled small blocks. Low 9 second 3500lb street cars that drive 35 miles to the track in Florida heat.

How much HP. I run low 900 on one and 850 on another. I do not know torque. It is a 300 shot on the 900HP motor, and a 400HP hit on the 850HP motor. But more important a concern then torque is stroke, the bigger and heavier the crank, the more abuse to the bottom end. I run a 3.75 stroke internal in one motor, 63 lbs at 900 HP, no problems.

Heating on the street This is a issue, but not water temp, but oil temp. Plan on a big oil cooler or you will see oil pressure drop the longer you cruise. The filler become a heat sink once it is all warm. The oil cools much slower.

2 bolt converted / splayed is the way, 4 bolts suck for reasons stated above, but it is less critical with a 350 small bore then a 400 bigger bore block

I would highly suggest a 400 over the 350. the power potential is a huge difference, and 2 bolt 400 are damn near free. Just the advanatge in the larger cylinder unshrouding the valves is reason enough

[toddshotrods]

Thanks Frank. I knew there was someone on this site that had been spraying pretty heavy. Aren't you using progressive controllers?

Maybe I'll build my 377-inch dream motor.

[ProdigyCustoms]

I have a progressive on board, very rarely use it though. Since all the ET is in the first 60', I like it all NOW! I did have to use it in Pigeon Forge because the track could not hold it all. And I use it on the street sometimes because it is hard to contain it all, but I like 100%.

Depending on car wight, I would build a 377 also. If it is less then 3000LBS, it would be perfect. The short throw crank won't put much stress on the bottom end, and you get the big cylinders. And it will rev, rev!

[toddshotrods]

...And it will rev, rev!

That's the part that floats my boat!

What size/brand tires are you running to hold an instant 100%? Someday, somehow, I gotta make it down there to visit you guys. Would be nice to come when you're planning to go to the track...