BB vs SB on 10 cub

[WINDYCITYJOHN400]

Ok, now that I have the keyboard as well I'll add my 2 cents.

 

The 421 (4 mill) and 465 (10 mill)  cubs are not the best match for a BB pipe. (As a matter of fact, Mat's newer SB OOF pipe was completely redesigned following the massive interest of the 4 and 10 mill motors so that it would be the hands down best pipe for Alky in those size motors.)

 

Many have run BB's, but it is a compromise pipe choice. Many do it because they think that bigger is better. Mat designed the BB pipe for 535 and higher. 

 

People who run the BB pipes on smaller motors and claim better numbers than SB pipes, are usually running high compression and really advanced timing. That tricks the pipe with the amount of heat that is put into it. The pipe starts to "Act" like it's smaller. So that's why sometimes a BB pipe can work. But Ideally you could make a simple adjustment to the dome and with less compression and timing, make more power with the SB pipe than you would with the BB pipe.

 

I'm amazed at the number of people who will buy or build a motor and then start wondering what the best pipe choice is. Nobody is running crazy off the wall timings that have never been tried. This topic has plenty of people with skin in the game. Your port timings and compression levels will be a strong dictator of what pipes will even be close to a match. A simple call to your builder or a pipe builder will give you 90% of the info your going to need.

 

The relationship between your domes and pipes are also very important. Making a simple dome change can do a lot to get a motor and pipe working well together. Timing is key too. So many people think that running crazy amounts of advanced timing is like turning up the wick and making more power. 

In reality it's more of an indication of a problem with the activities in the combustion chamber. (Why would you have to light the air/fuel mixture way before the piston hits TDC if the burn was happening effectively?) 

 

Long story short.....many have developed practices they think work, but aren't aware of why. Why is high compression and advanced timing favored by some?.....Because they also felt their motors were So Bad Ass that a SB pipe didn't sound impressive enough, so they went BB. Side effect was they had to run a ton of timing to make the pipe work like a SB pipe would have. 

End result - They tuned to the wrong pipe.

Now if those people slap a set of SB pipes on....the SB's will be WAY down on power due to all the things they set the motor up with to optimize the BB's as best they could.

 

I'm not saying that there are hard and fast rules about pipe choice just based on motor size. But if you think your motor needs a BB pipe when the SB pipe was designed for your size motor......then I'd only say you should be able to describe WHY.

Same goes for people that say "Mine liked the BB's better than the SB's"........WHY? 

It's OK if they don't know and don't care. But it's in turn, an indication of the lack of understanding as to what is really going on and without the bigger understanding....they also miss out on the bigger picture and the better choice they might have been able to make.

 

PERFECT EXAMPLE -

My 472 Cheetah first hit the dyno with CPI BB In-Frames (On the advice of Mike at CPI as well as all the dune riders who claimed the CPI's have better bottom end.)

 

Swapped to Shearer BB In-Frames and gained 14 HP!!!! 

 

Swapped to Shearer SB In-Frames and kept the same top end power and the bottom end torque curve matched the CPI's perfectly. Final pipe choice netted all the top end as well as low end with no trade-off's.    (Both Shearers pulled about 800 more RPM's over the CPI's as well.)

 

But most important in that lesson was coming to the understanding as to WHY I got those results. Always ask WHY! The answer IS NOT "cause it made 5 more HP on the dyno." The answer IS NOT "Cause it went 2 tenths quicker at the track."

[shanYE west]

how did I know this novel was coming as soon as I saw the thread.   

[WINDYCITYJOHN400]

Real information comes not in burps and farts of small puzzle pieces, but in soliloquies of content and context.  

[vulvafan537240]

Long story short was funny

[#1JUANstunna]

soliloquies = is a device often used in drama when a character speaks to himself or
herself, relating thoughts and feelings, thereby also sharing them with
the audience.

[shanYE west]

Real information comes not in burps and farts of small puzzle pieces, but in soliloquies of content and context.  

was this even english? 

[Wheelman Chassis]

I have run both on the same motor, IMO  the small bores worked just a tad better.... HJR ported 10 cub.   I will say the bb had just a bit more up stairs in the dunes..

[shanYE west]

i've ran both on my 421.  Dyno showed better front side curve with the BB's with same peak HP as the SB's.  On my brothers 10 cub we're using BB inframes.( as suggested by the builder)  He has used sb oof's in the past.. No dyno data but it does run better with the BB inframes.

[WINDYCITYJOHN400]

With no information as to WHY..........

[locogato11283]

I would find it hard to believe that on every motor, every setup and every use on a 10mm Cub that the SB would be better.

 

There are far too many variables that come into play.

[possum]

 

i've ran both on my 421. Dyno showed better front side curve with the BB's with same peak HP as the SB's. On my brothers 10 cub we're using BB inframes.( as suggested by the builder) He has used sb oof's in the past.. No dyno data but it does run better with the BB inframes.

what was the dome setup, compression and porting?

[J-Madd]

I have back to back track and dyno runs somewhere for this scenario. On my particular motor, it didn't make much difference. I think the BB peaked at about 400 rpms or so less,but the HP and e.t.s were similiar (from what I remember). If I get time I can dig up the post. I think its on atvdragracers.com

[WINDYCITYJOHN400]

I would find it hard to believe that on every motor, every setup and every use on a 10mm Cub that the SB would be better.

 

There are far too many variables that come into play.

I never said every 4 or 10 mill motor would need the SB pipes. (But I at least attempted to explain the variables and why understanding them is important.)

 

But why does everyone seem to think "Their Motor" is the exception to the rule? (Cause they are stuck in the bigger is better mentality.)

 

You swapped from Original Rockets to BB Shearers and didn't even talk to your builder about it. Why? What would lead you to think a pipe designed for a 535 cc motor would work best for a 465? What "Variables" were in play with your build?

 

You have always been vocal about your fondness of the Original Rockets.......How do they compare to SB and BB Shearers? Where do they fall in terms of size? What port timings are they designed for? What are the heat tendencies? What made you switch to BB Shearers?

 

The point I worked so hard to explain is that unless you understand WHY a motor liked one pipe over the other.......you don't really have a complete grasp on the comparison.

[locogato11283]

I never said every 4 or 10 mill motor would need the SB pipes. (But I at least attempted to explain the variables and why understanding them is important.)

 

But why does everyone seem to think "Their Motor" is the exception to the rule? (Cause they are stuck in the bigger is better mentality.)

 

You swapped from Original Rockets to BB Shearers and didn't even talk to your builder about it. Why? What would lead you to think a pipe designed for a 535 cc motor would work best for a 465? What "Variables" were in play with your build?

 

You have always been vocal about your fondness of the Original Rockets.......How do they compare to SB and BB Shearers? Where do they fall in terms of size? What port timings are they designed for? What are the heat tendencies? What made you switch to BB Shearers?

 

The point I worked so hard to explain is that unless you understand WHY a motor liked one pipe over the other.......you don't really have a complete grasp on the comparison.

 

John, here's the difference between me and you.

 

You're a keyboard racer. I am a real racer.

 

I've won all kinds of shit with my proven set ups, 10mm Cub with BB pipes included.

 

Let me know when you've done more than sit on your keyboard and type a bunch of long-winded posts.

[shanYE west]

what was the dome setup, compression and porting?

As requested.. thats information I'm not at liberty to discuss.  but I will say.. compression and timing were not unusual or radical.

 

With no information as to WHY..........

Dont really care why..  he explained to me why..  but it went in one ear and out the other..    I operate a Pro Shop.  Customers come in and tell me what they are looking for.  I make my personal educated suggestion (similar to what builders do) 9 times out of 10.. the customer does not even care about WHY it does what it does.. or WHY it performs differently then something they currently have.  They just care about the end result.  The 1 customer out of the 10 that does ask why..  I explain the technical specs and explain why it does what it does..  but.. he dont understand it.. but he'll go and repeat it to people as if he does understand.  If he did truly understand it.. then why is he paying me?

 

Long story short.. I leave the super technical stuff to the pro's to understand why.. thats what I pay them for.  I just care about the end result  which was actually was about .1 faster on average over the SB's and had my fastest ET.