Small Block vs. Big Block

True, True. Here are some definitions:

SB - Boost - How many lbs will my piston rods take?
BB - Boost - How far will the gas pedal go?

SB - Modular - How many pieces does it take to equal BB torque
BB - Modular - Add gas, press gas, have torque

SB - EPDCM - Every Problem Directed by Computer Module
BB - EPDCM - huh?

SB - Torque - HUH?
BB - Torque - Need more

:D :D
 
If someone goes for a ride, can you pick me up?
 
You are so correct. Seems that when all the huge rotating mass gets going - all of the bolts start to loosen up on my car, the cars next to me, cast iron cracks, and hardened steel folds like tissue paper. I guess that's the cross I have to bare.
 
Purple Venom said:
True, True. Here are some definitions:


SB - EPDCM - Every Problem Directed by Computer Module
BB - EPDCM - huh?

:D :D
Click to expand...

See you can't even the Acronyms correct:

ECU = Engine Control Unit (old 5.0 EFI's)
ECM = Engine Control Module (SN95 term, everything electronic became modules)
PCM = Powertrain Control Module (this is what they call mine)
 
Big Block

A womans point of view:

The sexy sound it makes, the weight under your lap, the speed on the straights, and of course SIZE DOES MATTER!!
 
STL-Scott said:
See you can't even the Acronyms correct:

ECU = Engine Control Unit (old 5.0 EFI's)
ECM = Engine Control Module (SN95 term, everything electronic became modules)
PCM = Powertrain Control Module (this is what they call mine)
Click to expand...

My car has some of that too -
It's only availble on Big Blocks though
STHCOM - Scares The Holy Crap Out Of Me.
 
TBULL said:
After posting that thread i went out to the Powerdyne site and did some research. They were quoting an "Effective Compression Ratio" which is based on a calculation between your piston compression ratio and the amount of boost. Powerdyne states "Under normal circumstances with a Centrifugal blower you can usually run an Effective Compression Ratio of from 12.50:1 to 13.10:1."

I think I know what my piston compression ratio is, but like you said, with the X heads it may be running a little lower Effective Compression Ratio. Where can I get one of those gauges and can it be a temp mounting or does it have to be permanent. If it's temp, then we could both use it! I don't know about you, but I have been known to run mine at full throttle for a short time. :rolleyes:
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Dan,
Here is a nice selection of boost gauges at decent prices http://egauges.com/eg_typeI.asp?Typ...All&Manf=All&gclid=CNL35ubUgZgCFQ6jagodwTRJtg . They should really be permanently mounted for a steady reading. There are styles to match most gauges and they are easy to hook up. I don't think they are needed for "reasonable" levels of boost but if you want to go beyond that I would add one.
Tom
 
Tom,
I have autometer Ultralite gauges. I found a similiar one there that matches the rest of my gauges for $47. Due to my dash layout I can't really add another position right now. I have an Air/Fuel mix gauge, but it's aweful hard to see and it's constantly flipping around. Which would be more important to keep. A/F Ratio or Boost?
 
I would keep the air/fuel ratio. It's far more important to know if you are going lean than to know how much boost you are making.
 
I agree with Tom, too lean means burnt pistons. :(
 
Doesn't the older ECU systems manage the air/fuel mixture automatically? Just wondering...as I know the one for my modular motor does (it has sensors all over the place (Intake Air Temp, O2 sensors, knock sensors, Idle Air Control, Cam Position, Crank Position, etc. etc.) and adjust the timing, and fuel based on all of the above feedback.

Just curious.
 
STL-Scott said:
The one thing you cannot replicate in a SB that a BB produces in excess is Torque. Need I remind all of us HP junkies that Torque is the mother of all forces that kicks us back in the seat from a dead start. Lots of it at low RPM's in Tim's and Mark's beasts. I've ridden with Mark (and lived to tell the tale) and I was converted. I still like what I am building because I want something that is street-able and gas friendly, but there is no replacement for cubic inches. HP comes on at higher RPM's and sure it will make you go faster!
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Ahhhhh....not true.

What you state is true....if naturally aspirated. However when supercharged or turbocharged or with the addition of Nitrous oxide you are effectively increasing the displacement.

Think about this... At sea level a 302cu in engine sees 14.7 lbs of pressure to fill the cylinders. If you turbocharge that same engine to an additional 14.7 lbs of boost you now have 29.4 lbs of pressure filling the cylinders. You have at this point effectively DOUBLED the engine's displacement to that of the output of a 604 cu in naturally aspirated engine. This assumes equal head /cam technology. If you use a DOHC to turbocharge... the gains are even more dramatic

When I was racing the funnybike we were running 30 lbs of boost using H&H Blue Racing Gas. That same level of boost on a 302 engine would replicate the displacement volume of a 918 cu in naturally aspirated engine....!

That is why Turbocharging, Supercharging and Nitrous Oxide are so effective at making big power gains.

With one of these options you can easily exceed the torque of a naturally aspirated big block....as long as the mechanical strength of the engine can contain that much of an increase in mechanical and thermal stress.

That is where the 4.6 DOHC block excels. Extremely rigid cross bolted mains and a block that has successfully been used to produce in excess of 1500 HP. The weak link is pistons and rods. Even the stock cast iron crank is good for 650 hp. Once those are replaced... along with adding an optional forged crank...and you have an engine that is lighter than a big block yet can exceed its output, by a considerable margin...with the proper amount of boost, in both HP and Torque. The other benefit is that using a wastegate, the boost can be turned down for normal economical street driving and turned back up when you want to embarrass the big block crowd. The perfect street engine...

BTW...to replicate the output and torque of a 562 cu in big block using a 4.6 requires only 15 lbs of boost. A very manageable level on the street. Plus you still have the added benefit of more efficient cams and heads.

Just a little peek of things to come....:D

K&K
 
Ah, what does he know :D :rolleyes: :eek: Thanks Kerry, was waiting for your comments.
 
STL-Scott said:
Doesn't the older ECU systems manage the air/fuel mixture automatically? Just wondering...as I know the one for my modular motor does (it has sensors all over the place (Intake Air Temp, O2 sensors, knock sensors, Idle Air Control, Cam Position, Crank Position, etc. etc.) and adjust the timing, and fuel based on all of the above feedback.

Just curious.
Click to expand...

Loved Kerry's info above and as to the fuel air management, when forced air or nitrous are introduced extra fuel must be provided beyond the ECU's "thoughts". I run an 8:1 disc in my fuel management unit (FMU) that adds 8lbs. of fuel pressure for every lb. of boost to keep from going lean. I also run a boost sensitive fuel pressure regulator that does the same thing as a backup. The same thing can be accomplished by ditching the FMU, going to larger injectors, recalibrating the MAF sensor and going for a tune. This is what I will do should I choose to increase the boost since I'm running my injectors at around 90% duty cycle under full boost now.
 
Mark, I think we're outnumbered and outknowledged on this one :rolleyes: :D
 
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