Ok, the 350 and 400 SBC blocks are what you would use to do a performance buildup.

How much better are "bow tie" blocks? I've seen them in mags for like 2k and I'm wondering what makes them better, what is the difference in power range from a standard 350 SBC and a bow tie 350?

i was just wondering.....what is the difference between the 350 and 400? is it a stroke/bore increase or just a stroke increase?

 

They will make exactly the same amount of power, as far as that goes.

They are much stronger, so whenever you do start making big power numbers, the block is more stable.

The 350 is 3.48" stroke x 4.000" bore; the 400 is 3.75" stroke x 4.125" bore. 400 blocks also use different main bearings; the main journal diameter of a 400 crank is larger than a 350.

 

is there a general cut off?

like

350 : 500HP

bowtie 350: 500HP+

thats sorta what i was looking for....as far as stability, it is just engine life? the bowtie will last longer? or is it a matter of the chance of the block failing increases as the HP increases...

 

There's no "cutoff".

How much life insurance do you "need"? What's the "cutoff" for that?

The block thing is a bit like that: if you or I were to build a 500 HP motor out of a stock block, it might go 200 passes, or 100,000 miles, or 10 30-lap events with qualifying and heat races (my personal type of benchmark when I was building motors as professionally as I ever have); it's not as if a 501 HP motor will immediately grenade the first time you hit the key. It's more like, if I built 10 600 HP motors, 5 of them might make it through 2 30-lappers, but out of 10 Bow-Tie block motors, they might all go through 5 such events. At 8000 RPM only half of stock block motors might last 10 minutes, but half of all Bow-Tie blocks might go 20 hours at that RPM; and you'd get to the 10-minute half-life out of Bow-Tie blocks at 9200 RPM.

There's tradeoffs everywhere you look. Weight vs. strength, speed vs. longevity, money vs. power. There's no hard and fast dividing line on any of those.

 

Take a high performance shop.

If you go to them and say, "I want x amount ofRWHP" street and light dragstrip duty on the weekends. What would they say? When would it go from a regular 350 block to a high cost bow-tie (all the ones I've seen are 1500$+)


http://www.vetteexplorer.com/cgi-bin/mv.pl

That that for example, the guy has blown 732HP 400 bowtie block. The building didn't stroke to 427 because he wanted to keep some extra meat in the bores. I am going to assume that the whole dynamic changes when you go from NA to forced induction but in general, when would it go from a standard 350 block to a bowtie 350 block? At what horsepower does realiability become an issue? I'm going to figure that a shop would play it on the MUCH safer side since they don't want to have their engine fail because they didn't use a strong enough block. I've heard that SBC's fall apart after 400RWHP, then again there are those who put 600HP and a 150 shot on a regular 350 and they have no problems....but when does the average "common sense" line get drawn? I'm more looking for someone who is willing to say "x HP will probably not lead to a long lifespan for a regular block"

 

RB is just saying that it doesn't matter so much about HP, it's about endurance.

Kind of like "The World's Strongest Man". Sure... One guy can lift XXX lbs. over his head, but HOW MANY TIMES or FOR HOW LONG can he do it before one of his arms breaks?

If Ben Affleck (stock SBC) lifts 300 lbs. over his head 10 times, he is more likely to break one of his arms than if Arnold Schwarzenegger (Bowtie) lifts 300 lbs. over his head 20 times.

Does that help?

 

Ok let me try this once again, STREET MOTOR (meaning it must survive as a daily driver as well as light drag duty)

When does a standard 350 not offer enough security? What horsepower? If your not experienced or confident enough to answer then don't. I just want someone to flat out tell me when they think it's good to switch to a bowtie. 500HP? 600HP? Yes, if you are pushing 400HP safely from a regular 350 then 475HP shouldn't be a HUGE deal, but when do you say, "enough is enough, it's time to go bowtie", factoring in that a bowtie costs 5-10 times as much as a regular 350 or 400. Assuming you want the best deal between cost and possible durability.

Basically your answering my question like I asked what is better, forged or stock bottem end. I know, a forged bottom end won't neccesarily produce any more HP then a stock, but a forged will be more durable and less likely to fail. Gee, I didn't ask that, I'm asking when experience says to switch from stock to forged, or in my case, standard SBC to bowtie.

 

If it's anything remotely dimly near streetable, not just a trailer queen that happens to occasionally use the street as a track, then a stock block is fine.

I would maybe create a convenient definition of the "time to switch" in terms of prize money, just for a reference. Not the money for one race, but maybe a season's worth of what you could realistically stand to collect by stepping the motor up a few notches within your class rules.

What you're fishing for doesn't really exist. Again, it's exactly the same question as "how much life insurance do I need?" There is no hard and fast, cut-and-dried answer to that kind of question. It's all about risk, reward, expense, and savings. Only you can make that kind of determination of how much money the risk of a block failure (or a block-preventable motor failure) is worth to you, as you are going to be using it.

Another way to look at it might be, when the price of the block ceases to be a significant factor in the overall cost of the activity. If it costs $8000 to build the car, that block looks mighty pricey; on the other hand, if it costs $250,000 to build the car and enter it in a race, it's real cheap. Just who are your co-workers on Sunday afternoons going to be, anyway?

 

In the article Hard Rock Camaro it states that Garry Grimes of Grimes Automotive Machine prefers to use a bowtie block when an engine is expected to exceed 500 hp. Hope that helps you somewhat.

 

THANK YOU! The first answer to my question.

 

That would concur with a similiar question posted on a recent Chevy Hiperformance Magazine. The question was in regards to a 400. They felt that a two bolt main 400 converted to 4 bolt mains using billet main caps was good for 500 hp. Beyond that, they would use a Bowtie or Motown.