Everybody is always asking "how much hp can my parts take", so I will give these experienced based off the cuff rules of thumb. The fact that a friend of a friend has a 1,000hp small block with stock crank and rods that he puts 15,000 miles a year on will not hold much water with me. So I won't bother to debate it if you bring it up. But intelligent comments are welcome.

So, here's some rules of thumb for max hp based on reasonable longevity. It doesn't really matter how you get there, it's based on the mechanical strength of the various engine components. There are exceptions, such as a centrifugal SC will tend to put more stress on the motor for a given hp output due to the need to use up hp internally to drive the blower. The numbers refer to production small blocks, big blocks can take more.

I. OEM parts: 1-1.25hp/ci. ~350-450hp
II. "Entry level" aftermarket parts (say Eagle/SRP kind of stuff, basic block prep): ~2hp/ci. 700-800hp
III. "Top shelf" aftermarket parts (Callies, Lunati, JE, etc., full block prep): 2.75-3hp/ci. ~1,000hp or maybe a bit more.
IV. Best of everything (including aftermarket block at the higher end): 3-3.5hp/ci. ~1,200hp

Rough approximation of costs for short blocks in each group:
I: you already have it
II: $3-4,000
III: $5-7,000
IV: $10,000-20,000

Please dispute or confirm my numbers, I am bored. I hope to generate some discussion here, since I can't be out racing and I don't have all the parts for my motor yet and can't put that together either. BTW: it's a "Category III" and I plan to push the limits!

Rich Krause

 

Rich, what is your take on n2o horsepower. Would you say it's more stressfull than SC? (Given proper tuning and comparing same add-on power levels, i.e. say 150hp boost from n2o vs 150 hp boost from SC.)

 

looks pretty good. I will relate what I was told in the last week on some parts I have been looking at.

Mainly the Eagle stuff. I am buying a Motown Block and was looking at maybe getting a Motown short block ready to go. The Boys over at HardCore Performance/World Castings Assured me they would hold 1,000HP no problems Putting that stuff in the 2.34 per cube rule. They also offer a 2 year 2,400 miles warranty on the Assembled short and long blocks for street use.

I told them what I was wanting(600-700hp plus 300 shot) and they said it should hold up great.

This is just what I was told

 

n20 camaro , n2o has more of a intall shock compared to a sc that slowy adds power. as for a 150 hp of spary vs 150 hp with a sc I would say the n2o would have less stress, for one you can lessn the sudden spike by multie staging. A sc depending on the amount of boost will put a load on your crank snount. Also a sc can not be turned off the psi can be less(drive at low rpm) but I preffer the flip of switch and turn it off. I think of n20 as natural aspiration in a bottle.


I am a big fan of spray but Im sure a sc guy will come along and straighten me out.

 

At the 150hp level I'd say it's nearly a wash with the nod going to the N2O.

Rich Krause

 

Kind of related to (n2ocamaros) question. When it says say 1000 hp limit. Would that be mainly N/A hp, like say you have a motor thats 1000hp N/A and one thats 800N/A and a 200shot, would the nitrous motor not hold up as well as the N/A motor even though they are the same power level?

 

That's a finer point than my guidelines were intended to address. OTOH, the NA motor will have to rev higher. OTOH, the "shock" of the N2O can break parts, especially if it's not staged. Overall, I'd give the nod to the N2O setup because a 1,000hp NA small block is gonna have to rev through the roof. Obviously, there is a certain level beyond which NO NA setup can make hp, and a 1,000hp small block would be getting into that range. So, I am just speaking hypothetically.

Rich Krause

 

Good idea on writing a topic like this. My question is more specific if you don't mind me asking: What is an LT1 with forged pistons and rods (stock crank) good for in a forced induction set-up as far as hp is concerned? What is the highest anyone has pushed that type of set-up?

Thanks

Andy

 

I think those are just very generic ratings, not meant to be specific in any way, like it says it all depends on mechanical parts, if its a 50k mile crank might not last as long as a 10k mile crank...etc...etc...

I think what someone that has too much money (that they dont know what to do with), needs to do...is build a whole bunch of engines, and just test them to their limits. I would love to do this, get a 3rd gen or something to easily intall/remove an engine. Keep the same top end, just change around the bottom end with different combos, and keep throwin N2O on it till it breaks. Wouldnt be all that expensive until you get into the high dollar internals.

Edit: haha, better yet, a good businessman, talk to crank/rod/piston manufacturers and get them to sponsor something like this, dont really think its been done to my knowledge, at least not several different bottom ends with same top end and drivetrain and such

 

Hey Rich, did you know Big Daddy Dwayne Guthridge has been running the same Eagle Crank and Eagle H-beam rods for the last 4 years? He went 7.92 a few days ago on drag radials..

All I'm saying is the tune has as much or more to do with longevity than the brand name, when comparing 4340 stuff or forged pistons..

I ran the GM forged crank at over 900 HP ( I was told it would break, but it didn't)

I'm not a believer_AT ALL_that you have to spend cubic bucks to go fast, but you DO have to spend time tuning it...

what is 1500/380 it didn't make your list..

with that being said, I went with a dart block/billet crank/carrillo rods/ ross pistons setup for the big turbo project.. I should have the car back in my care in a week

Happy Hotrodding

 

I've seen the Eagle crank and H-beam rods time and time again making 800-1000rwhp with ease. One of my mustang buddies has been making 950rwhp for over a year now in his A4 block 306ci stang running Twin T66's and Eagle rotating assembly.

Jose

 

wow rich, u really think this is true? I have no real idea so that is why i'm asking. This winter i have built a early 70's '010' block, 4 bolt mains, Lunati 'Pro Mod' 383 rotating assembly, AFR 210s 100%cnc'd, solid roller, victor jr. intake, and demon carb. I will be having it dyno'd shortly but the estimates have been between 600-650hp NA. My engine guy 'Mike Janis from Jan-Cen Automotive' suggested that i dont take the block i used over 650hp, he said i'd be pushing its limits, he suggested going with an aftermarket block after the 650 mark.. This came up because I wanted to toss on some NOS after i get it running LOL.. However according to ur limit chart I will be more than OK! How sure are you about this? Or am i just gonna have to be the guiny pig and test it out LOL

Money spent on Short block:
Block work = $7-800
Lunati Rot.Assembly = $2800 (includes rings, bearings, etc.)

Looks like i'm way under the limit here, what am i forgetting?

Engine Long block total = $8500

 

Well, you can see from the responses that there is a divergence of opinion on this subject. I wouldn't think you are going to have any problems at all with the block if the prep has been done right and it's in good shape. The block you have is most likely better than the LT1 blocks that many of us are using and making a lot more than 650hp. I would consider an aftermaket block mainly if I wanted to make a really large displacement small block and wouldn't worry about basic block integrity until the 1,000+hp range. Of course, I am talking about drag racing or street/strip use. If you are talking prolonged periods of WOT (closed track racing primarily) it's a different story.

Rich Krause

 

OK Mr.Krause

Block: Stock except for being magged and honed
Rods : Stock rods w/arp bolts
Crank: stock(balanced)
pistons: TRW forged
Rngs: JE/hellfire
Cam:224-236 lsa-114(low lift)
bearings: Federal Mogul(file fit)
compression:9.2:1
heads:stock lt1 castings
Boost:12-14psi(p-600b)
alky injection:smc enterprises
N2o:tnt wet kit(75-100hp)

I know Im going budget with this setup, i assure you the next one will be much better as far as bottom end goes. But for this setup what do you think the hp limits are? and do you think I'll be exceeding them?

 

Depends how you use it. It probably won't self destruct the first time you use the nitrous. But if you run it hard very often I think you are looking at some problems with the bottom end. You are asking a lot of the stock crank and rods. And there is going to be some movement in the bearing caps when you really get on it. \\

Rich Krause