Rant about "how much hp can my block take"

I am really tired of hearing discussions in the form of "how much hp can (name your part) take?" Especially in the context of cylinder blocks. While I am far from any kind of expert in failure analysis, I know that most automotive component failures are not due to a single, sudden stress that exceeds the ultimate strength of the intact, new, undamaged component. These parts fail due to fatigue, whic is caused by repeated loading and unloading of a stress on the part. Microscopic cracks develop due to metal fatigue. There is progressive damage due to fluctuating stresses and strains on the material. Cracks initiate and propagate in regions where the strain is most severe in three stages.

1. initial microscopic crack forms
2. crack progessively enlarges across the part
3. there is a sudden final fracture of the remaining cross section.

In materials testing, parts are subjected to different stress levels to produce an "S-N curve". The Y-axis is stress and the X-axis is number of cycles to failure. That S-N curve allows designers to make a direct estimate of the expected life of the part in terms of stress — a basic design parameter. By locating on the graph the number of cycles similar to that expected during use of the part, designers can identify the appropriate design stress. The "fatigue strength" of a part is refers to the number of cycles a part can endure at a given stress level. Ferrous metals also have a property called the "endurance limit". Below this level of stress, an "infinite" number of cycles can be withstood.

Most of the areas of the block are probably below the endurance limit and will "never" fail absent corrosion or other accidental damage. About the only "block failures" I have seen were on forced induction or nitrous motors that had been bored out. In that situation, cylinder walls will split. Crankshft failures may be related to block design. If the main bores are are not sufficiently rigid, there may be flexing in the main cap area leading to main bearing failure and eventual crank failure/damage. There may be failures related to improper assembly. I have seen cracking through the head bolt area into the water jacket due to overtightening of head bolts/lack of material in this area. And so on. But block failure per se is exceedingly rare.

Rich

What Rich said above. Well put.

Well, I just had a block that was good to 700 HP. At 701 it went *POOF!*
So THERE! :D

Very informative :)

As a consumer, do we ever get to look at/compare these "S and N graphs"?

The GM 4-bolt block is excellent for a high performance engine... you just need to add billet caps. George Baxter used the straight 4-bolt GM block for his 1,125HP 9.04-second LT1 setup. When the engine was torn down, it was in excellent shape, and the block is being reused in an 1,100HP nitrous setup.

figured i would put it here for him!!

seems like every post i read from fred has something to do with baxter...just picking on ya man!

Well, I just had a block that was good to 700 HP. At 701 it went *POOF!*
So THERE! :D

There you go again! Everyone knows those blocks are good to at least 702hp :p

Rich

There you go again! Everyone knows those blocks are good to at least 702hp :p

Rich
is that SAE corrected?

is that SAE corrected?

:p

Rich

I hope your thread was not directed at me at all. The main point in my asking was specifically at what point would a move up to a Bowtie be benificial in terms of dollars spent. Im just thinking long term. I know you cannot put a number on how much a block can take, I was more looking for a roundabout figure with proper block prep. As you can see from my last post in my thread I got 2 completly different answers from 2 different builders, people with over 30 years in the buisness,in other words more experience than most here. Im just trying to cover all bases. Its just the most logical thing to do when spending your money.Anyway my block is not a LT1 casting , I dont know how it differs if any in strength from the 86-92 castings. I checked the search and could not find enough info to answer my question, so i posted my thread.

Go to http://www.key-to-steel.com that will tell you a lot about how steel and cast iron break.

I hope your thread was not directed at me at all. The main point in my asking was specifically at what point would a move up to a Bowtie be benificial in terms of dollars spent. Im just thinking long term. I know you cannot put a number on how much a block can take, I was more looking for a roundabout figure with proper block prep. As you can see from my last post in my thread I got 2 completly different answers from 2 different builders, people with over 30 years in the buisness,in other words more experience than most here. Im just trying to cover all bases. Its just the most logical thing to do when spending your money.Anyway my block is not a LT1 casting , I dont know how it differs if any in strength from the 86-92 castings. I checked the search and could not find enough info to answer my question, so i posted my thread.

Nothing personal at all, that why I started a separate thread. Please accept my apology if you took any personal offense. It's just that the concept of a block being good to some specific hp number doesn't make any sense.

Rich

No problem Rich, I do agree you cant put any number on how much a block can take since many have shown #s of how much they have put through them. I was more looking for the information of how they got the block to withstand x amount of hp and tq. It seems to be the running consensus that to be able to survive 600+ hp is to run block fill and studs, something I didnt even consider(aka block fill). Just so much misinformation out there its tought to shift through it. Thing I found funny was the one builder I talked too completly disregarded block fill as not nessary and to forgo it for splayed caps. Correct me if Im wrong but I think you,Rich, as many others running where I will be putting my block all run block fill. Anyhow, no offense taken. Its benificial to talk with many here to actually see what they run and what they did to get there.Good day

Thanks for graciously accepting my apology.

I am a big believer in partial block fill for stock blocks subjected to very high stress. I doubt if it helps the block per se, but I think it helps the main caps from moving around which can lead to bearing and failure and a messed up engine! Again, as has been said before, limiting overbore will help the block survive and will help it make power by promoting good ring seal. At least for forced induction, I'd give up the added hp from the bigger bore for less bore distortion. NA I'd go for the bigger bore though.

Rich

Rich, could you tell me who put your motor together for you and where they are located. Im in the market for a builder, and want to get started asap

Rich, could you tell me who put your motor together for you and where they are located. Im in the market for a builder, and want to get started asap

You may want to talk to Bret Bauer who can be reached at
bret@bauer-racing.com He is very knowledgble.

My machine work was done by Proformance in Rochester, NY and assembled by myself and my friend Bob. You can reach Matt at:
Proformance Specialties
(585) 288-1499
1115 Main St E
Rochester, NY

Rich

Hmm I guess you just need to know how to build them then. 1500 HP here on an LT1 block, it's in perfect condition, no block failure. Main bearings look brand new.

figured i would put it here for him!!

seems like every post i read from fred has something to do with baxter...just picking on ya man!
Welllll..... I could tell you about my engine, but it isn't very exciting. In general, I try to avoid posting "my friend's mistresses's brother knows a guy who built a 3,000HP V6....." and only post information that I am familiar with on a first-hand, hands-on basis. Baxter's engine happens to be the only one of that scope that I've ever had a chance to work with/on. If I'm boring people with this info, I'll just back off.

Welllll..... I could tell you about my engine, but it isn't very exciting. In general, I try to avoid posting "my friend's mistresses's brother knows a guy who built a 3,000HP V6....." and only post information that I am familiar with on a first-hand, hands-on basis. Baxter's engine happens to be the only one of that scope that I've ever had a chance to work with/on. If I'm boring people with this info, I'll just back off.

Please don't Fred! I feel you and all the other guys on here that have 'been around the block a time or two' have VERY useful information! Whenever I see a thread similar to this, I always look forward to what you guys have to say.

Keep up the good work!!

It's just getting the the point that no matter what I post, someone has to bitch about it..... it gets tiring after 16,000 posts or so. :rolleyes:

It's just getting the the point that no matter what I post, someone has to bitch about it..... it gets tiring after 16,000 posts or so. :rolleyes:

Hey, "they" only seem to bitch if a post has excellent high- quality information or absolute junk BS. Your posts (of the former kind) are highly valued by most of us, Fred.

Remember the old motto, "Illigitimi non carborundum"

Besides, I really like your avatar (or what ever that pic is called).

BTW: INJUNEER--I was one a long time ago.

Thanks for graciously accepting my apology.

I am a big believer in partial block fill for stock blocks subjected to very high stress. I doubt if it helps the block per se, but I think it helps the main caps from moving around which can lead to bearing and failure and a messed up engine! Again, as has been said before, limiting overbore will help the block survive and will help it make power by promoting good ring seal. At least for forced induction, I'd give up the added hp from the bigger bore for less bore distortion. NA I'd go for the bigger bore though.

Rich
On the subject of main caps moving, isnt there some sort of cap girdle? It ties all the caps together. I remember reading about it but cant remember where.
-Mark

For how much power the LT1 block can take, I'm suprised that most people agree they should not be bored more than .030-.040 over.

I've seen many regular SBC blocks taken .060 over.

What is the difference in bore thickness between an old SBC and an LT1?

Is it a possibility that even if the LT1 bores are thinner that they are still stronger because of better manufacturing/materials?

Just trying to figure out why the LT1 blocks seem to take so much more than a regular SBC. (or do they?)

On the subject of main caps moving, isnt there some sort of cap girdle? It ties all the caps together. I remember reading about it but cant remember where.
-Mark

Like This..... (http://home.wideopenwest.com/~squinn0039/LT1.jpg)

It's more of a Ford trick than a Chevy one, but basically it's going to stablize the caps more at the top of them. It's fun to fit in a Chevy oil pan because they are not the norm and some of them even make you cut the tops of all the caps flat (if they are not) to get a good mating surface. The old man had to fix some Windsor caps years ago for my brother in laws stroked Windsor, back when you didn't have Windsor stroker cranks, you had 400M cranks made to fit in a Windsor block. Well at least I have a high nickel '69 Windsor block from all of that.

Bret

I agree that there's no exact number on hp or tq a block will take but rather how much extended engine life you can expect our of it at a certain duty cycle at a certain power level and a certain rpm. The block that we used in Rick's engine was fine but after the turbo exploded at Thunder, it probably got metal into the shortblock which killed one rod and piston probably when it tried to compress that? Anyway the rest of the block as in bearings and pistons looked great and before that the engine was also doing fine. 1400+hp is not easy on anything but with safe tuning it was hanging in there.

Now a real Bowtie or DART or World would certainly be better and would last much longer that's for sure but Rick was going for the LTx record and so we kept the LTx block. Soon we should be in the 7s with the LT1.

I think the main girdles are sort of an abomination for the most part but hey plenty of shops make money off of them! As Jud says at the school at least it keeps the Ford guys from running over the crank! Now they even have top and bottom girdles for the Ford stuff. I'd say that if you need all that it's time for a real block!

Wow! Bret, that girdle looks like it's aluminum too!

It's just getting the the point that no matter what I post, someone has to bitch about it..... it gets tiring after 16,000 posts or so. :rolleyes:


i do not approve of this post.


in all seriousness, I just stopped posting in tech sections on the net. well aside from this one. its so pointless.

myth and rumor snowball into quantity on the internet. the strength of these myths and rumors are valued to a much greater degree than intuition, logic, science, R&D and expierence. The internet is a terrible place to get your roots.

If i had "learning" to do over again, Id start with sport bikes. you can REALLY see how things interact very well there because they are so sensetive to modifications and are very very well tuned. not safety tuned like production cars.

Wow! Bret, that girdle looks like it's aluminum too!

That's a pic from Steve Quinn.

What did the one rod bearing that Rick's motor have fail look like? Did you see a big piece of junk in it or was is black?

Bret

No it got crushed on the top and spun so the rod was black and blue. This happened right after the turbo came apart at Thunder and the new turbo was installed and some dyno passes were made. Also keep in mind that this engine is still regular SBC wet sump stock oiling system. I am setting it up more like a regular race SBC wet sump this time and getting more oil to the center mains. All the other rods were fine. These were also Oliver rods that Rick has had since the beginning and were used with mucho NOS before as well too.

The block side of things looked great. All the main bearings still look new. No girdles of any kind and stock front and rear caps. Besides the turbo several other things happened at that race after we left the cars out that night. The main thing though is that the block looks alright and so do the cylinders. There was no cap walk so far and the pins and pistons also looked happy. Basically everything looked normal besides the one rod that spun. We'll see what happens this time as no one else is making the kind of power we are on one of these blocks but it certainly isn't an endurance setup.

How ugly was the piston when the parts of the turbo got in there? Obviously if the bearing is black and blue then it ran out of oil so for some reason the clearances tightened up to cause that. Fun stuff to figure out.

Bret

It's just getting the the point that no matter what I post, someone has to bitch about it..... it gets tiring after 16,000 posts or so. :rolleyes:


if you didnt catch it the first time, i'll say it again...i was only joking! ;)

i value everything MOST of the people in here have to say...including you fred... :bow:

i think block fill is in order for me over the winter. do i need to pull the engine out of the car? i have top end off of the motor as it is right now.

thanks
taner

Yes, removing the engine is necessary as the block fill will slightly distort the cylinder bores as it hardens & will likely require a slight hone to be sure the bores are round. The type & amount of fill as well as your cylinder wall thickness will change this amount of distortion, but you should be sure it has not runied any tolerances.

Did you get my e-mail by any chance?

Hope this helps.

You may want to be able to rotate the block as well to insure even and
thorough filling.

oh well **** filling the block till next time the block comes out! i planned on tearing it down NEXT winter, freshen bearings.

please resend lonnie, i think it was deleted accidentally

thanks guys!
taner