I've been reading and see that about 450 rwhp seems to be the limit for stock internals. If I put forged internals in there, what is a stock 4 bolt block capable of handling before things start to let go, either because of the block cracking or because of block distortion causing other things to fail?
I don't want to concrete it, it will be my daily driver in S Fla. I'll need every bit of cooling I can get. Thanks, Don.

 

Forged internals and 4 bolt mains could handle major power like 900 hp

 

George Baxter made 1,125flywheelHP with a 4-bolt LT1 block. No filler. Just better caps on the stock straight 4-bolt mains. And of course the forged carnk, billet rods and forged pistons. I believe Madman claimed 1,200flywheelHP on his low 9-second setup. Not sure whether he used a stock 4-bolt LT1 block, or a splayed 4-bolt conversion. I guess the splayed conversion.

The block from George's car was in good condition when he sold the engine, and is currently being used in an 1,100HP nitrous buildup.

 

You are asking "what is a stock 4 bolt block capable of handling before things start to let go, either because of the block cracking or because of block distortion causing other things to fail"? A question phrased liked this is not possible to answer as single hp number. Take a look at some of the posts in this thread http://web.camaross.com/forums/showt...hreadid=150191 to get an idea of how it's not generally reasonable to come up with a specific number for the amount of hp a component can take without failing.

About the best that can be done is to cite examples, as Fred did. But even Fred's informative posts leave out a crucial factor, which is "make how much hp for how long." IOW, not only does it depend on what parts are used, how they are put together, details of the setup, but on how it's used. A blower, turbo, or nitrous motor may be quite understressed and be virtually indestructible if you don't get into the boost much or turn the N2O on.

Suffice it to say that in in your context of a daily driver, the LT1 block is capable of being the basis for a motor producing more hp than you will end up making. One specific aspect of block prep that is often ignored is cylinder thickness. If you are going to a very high-po forced induction or nitrous setup, I would advise staying away form the typical 0.030" overbore and going with 0.010" or even a stock bore if feasible. The more rigid cylinders will help prevent bore distortion or even cylinder wall splitting under very high cylinder pressures, especialy since you don't want to do any block filling.

Rich Krause

 

by block filling... are you referring to filling the water jacket with hard block to allow a wider bore?

 

Excellent response! Thanks to all of you for your help and the time you took to help me out.
Good link. I read it just before I posted this.
I should have been a lot more specific with my post. Here's the plan. I'll pay the car off and do basic mods like exhaust, intake, nitrous. When it's paid, instead of getting another car,I'll just put some more money into better mods. First would be the forged internals. (Stroke that bad boy out How much will depend on finances vs costs and reliability of the longer stroke crank) After that's done and paid, I'm thinking s/c, heads, cam. I want to stay under 6k rpm. I've heard, and believe, that rpm is far, far harder on an engine than power is.
The funny thing is that with all this power I'm talking about I don't plan to spend a lot of time at max power. The reason I want so stinking much power is so that I don't have to thrash it. I want to give it partial throttle and have things happen. No muss, no fuss. Just effortless torque that seems to have no limit. I can be cool and relaxed and know that however much power I want- it's there and there's a lot more where that came from. The nitrous is a "just in case" type of thing. You know, just in case someone REALLY fast comes my way. Or just in case I want to go REALLY, INSANELY fast once every few months.
So here's the rundown. Low rpm, 6000 rpm or less. MAYBE 6500, but probably not. No hard launches, no slicks or DRs. A lot of power available, but not used very often. It'll be the classic understressed engine.
The reason I'm wondering what kind of power these blocks will take is because I don't want to worry about it breaking at all. I know power breaks things. I know my valvesprings will wear out more often because my cam will be harder on them. I know I'll need some serious valves because more power = more heat and the valves get a lot of it. But if the block is solid and able to take a couple of hundred more horses than I will throw at it once in a while, then I shouldn't have to worry about the total destruction of my daily driver as long as it is tuned properly and maintained properly.
It seems that the LT1 block, if machined properly, should be up to the task.
As far as filling it, yes I was talking about filling the water jackets. Summit actually recommends doing that to street driven cars to stiffen the block. I'm not sure how they recommend cooling the car after you do that, but that's another problem entirely. I'm sure they'll sell something to fix the fix.

 

Cylinder wall splitting? Now there's a thought to take to bed with me tonight.

 

Like Rich mentioned... how long do you expect it to last? I always look at engines as an investment & unless you're required to, I wouldn't build a big hp/big $ engine out of a production block. With killer aftermarket blocks being relatively cheap, I'd step up to something specifically intended for high hp applications.

 

I am just starting to look into this, so I haven't gotten into aftermarket blocks yet. Are they capable of larger displacements than stock while maintaining structural integrity? I'm also wondering what "relatively cheap" means. I know that machining can get very expensive, so the aftermarket block might not be as much more than a prepped stock block as it would seem to be. Do they usually accept the same heads and accessories? I'm planning to mod the stock engine and get the machine work done when I go for the s/c. I would really need it to take the heads and accessories that I'll have on the car at the time.

 

Phil makes an excellent point, but you need to know that the excellent aftermarket blocks are all the traditional gen I architecture. IOW, nearly everything that you have, from the pan up, will not be usable. You are talking about new heads, intake, ignition, etc. There may be some street gen I/4th gen hybrids, but so far I have not seen them. People who do this are generally building all out race cars. It's more than just a new engine, it's figuring out a whole bunch of stuff with a fair amount of custom work/fabrication.

Rich Krause

 

Ahh yeah, you'll be giving up some of the standard stuff, accessories etc., but I figured this was basically a street legal racecar with manners anyway .

FWIW, I believe Chuck machined some brackets to adapt his '97 accessories when he swapped to the sb2.2 434. If i recall correctly, he actually said he'd reproduce it and sell it if there was a demand for that sort of thing - it might be worth trying to get ahold of him if you're serious. Not that you aren't, it's just that everyone initially plans on building a 1000hp streetcar & that usually slips back to something more easily achievable without needing an obscene (to most) amount of money .

 

IOW, nearly everything that you have, from the pan up, will not be usable. You are talking about new heads, intake, ignition, etc.

Wonderful, just wonderful. I was thinking about an LT1 for a couple of reasons. 1- cheaper to buy, which leaves more money for the engine, tranny, cage..... 2- I had thought the more serious mods might be a good bit cheaper on an LT1 vs the LS1. Number 1 is still true, but number 2 may or may not be true. I want to keep all the goodies. This really is meant to be a daily driver. I want to enjoy the car even when I'm not running it hard. I'm amazed that no one is making LT1 blocks. I wonder if it's because the block is already very strong. Seems a bit unlikely, but the only reason I can think of for not offering something like this is a lack of demand. Since we all know there is a large demand for aftermarket parts for these engines, I can only assume no one would buy an LT1 block because the stock one is good enough for pretty much whatever gets sent its way. Hard to imagine the factory being THAT good, though. I really don't know what to think at this point. LT1 or LS1? I do know this much. It WILL be an F-body. No 2 ways about it.

 

Don't worry about the block.

Rich Krause

 

It happend to me.. it can happen to you!