Two of my buds are building different engines. One is a 572 BBC and 468 SBC both street car and fuel injection. Both Vettes have 3.08 rearend ratio, 4L80E transmission. Big Block cam is 270/278@.50, Small Block cam is 268/274@.50. does the rear gears have to be change to avoid the plugs fouling under low rpm driving? Is there a method of determining when to change and how much change would be required?

Thanks,
Yedi

 

D36 or D44 ?
I would be more concerned about changing the rear to prevent it becoming a pile of scrap metal on the street behind those combos

Sure they are at 50 numbers?
If they are , then are some serious duration numbers ; race motor territory.
Going to want some low gears and a loose convertor for them to work on the street

 

I think Nascar cams are smaller than the one in your smallblock. You better get gears at least in the high 4's to get that thing to move from a stop. I've got 4.35 gears with a 230/240 cam.

 

That 572 is going to be a MONSTER on the street.

I know how they run. A late friend had that sized engine in his Corvette.

Words can barely describe the shear power and torque and responsiveness on the street.

Enjoyed the power with him at least 100 times late at night testing, tuning, and driving with him riding shotgun.

His co-pilot. LOL

That 468CI smallblock wont be any slouch either,

Both animals.

 

The 572 Ci Big Block Chevy will make around 700Ft/lbs of torque at the flywheel.

Exact horsepower depends upon what cylinder heads are on It and rest of parts.

Like Brodex or Pontiac Big Chief Heads. Big HP then. See over 900 horsepower normally aspirated. No power adders.

Seen such engines dynoed in Joliet Illinois 1st hand.

Others like 383 and 421 TPI will have a better understanding of what the 468Ci smallblock will put out.

With the 572 Ci BB, you really dont need low gears for great performance.

So much torque on tap. You can get away with 3 series gears.

And still outrun most anybody.

Converter choice is crucial.

And if carburated , a 4-corner idle circuit carb with adjustable air bleeds would be of great help when tuning. And getting a semi-civil idle. Just barely with that camshaft spec you listed.

Brian

 

Yes those are 50 numbers

 

Nascar run around a 358 cubic inch and operate at 9000 rpm for a long time and higher compression.

 

Torque should be about 750, horsepower a little over 900 for big block, Small Block horsepower around 810, Torque around 670. The main concern is plug fouling and not lighting up the tires from a normal stoplight takeoff. No current plans to change to a solid rearend for as I know. I can't wait to drive these cars.

 

I have alot of experience with Super High Powered cars from recent past years.

Especially during our Boom years after 9/11 till the housing bust of late 2007-2008.

Everyone around Chicagoland and home was building high powered cars.

600 horsepower at the crankshaft was a slow car to most. LOL

I have a fair amount of experience with EFI.

But not as much as other C4 Forum members here do. The main reason I joined C4 a few years back. To learn more about EFI, and I learn from these other forum members every day.

The camshaft durations chosen probably wont work with any C4 computer, or any programming.

I may be be wrong, and others are likely to correct me......and thats OK. I dont know it all. None of us do..........

But I think you are going to need a Professional Drag Racing Grade EFI system and "BRAIN". Like an "Electromotive EFI System.

They are used in High end race cars, like NHRA Prostock, INDY CAR RACING, and other EFI Racing circuits.

And You need $$$$$ for that. $5K and up.

Simply awesome EFI systems. Have seen them in use myself.

As far a not fowling plugs on the street...........

There is only 2 ignitions up to the task, MSD 10 series ignition and matching hardware. Inductive fire style system. have to read on your own to understand why that is superior.

Or a VERTEX MAGNETO. A Magneto setup right will fire any gasoline or oil fouled spark plug like its still clean.

I prefer Magnetos for racing use................ I know alot about them and rebuild them for myself and a few racers I know. We love them.

Helps to have your own Sun Distribuatpr machine modified by you to spin test those magnetos to over 10,000 RPM's with all 8 spark gap racks set to 1-1-2" wide gap. Spin that mag up and give it hell...........

for 2 hours. If it dont quit firing or misfire for 2 hours straight at speed.

Its perfect.

My friend used a much smaller spec cam in his 572ci Corvette.

It ran fantastic yet.

But each to their own. Good luck and have fun !

Brian

 

By the way................

Driving any car or Corvette on the street with 800-1,000 Horse power is

No game to be taken lightly.

You have to be a VERY GOOD AND TALENTED DRIVER to put that gas pedal down and dont lift up.

You will see what I mean if you REALLY DO indeed have that 572CI BBC and 468CI SBC.

If you dont know what you are doing or screw up driving for even 2 milli- seconds.............

I can promise you that you are going die on the street.

And become an obituary in your local newspaper.

Why Do i say this..........?

Because I have known several that have died unexpectidley driving their 900 + HP cars around Chicago.

Young and unexperienced.

And a few drag racing.

A few hit trees at 160 mph.

They litterally exploded apart with their cars.

Not a joke................ really warning you.

FU@#%^^ and your dead, and others around nearby that cant get out of the way in time.

When your moving 200-300 feet per second, How can they?

Brian

 

Both of these motor run a DFI Gen Vll, if they run a lower gear example 4.11 leaving from a stoplight will bark the tire and could loose traction with the greatest of ease. Driving my 700 HP 434 with a 3.55 can be a kick into reality when I don't pay attention around town. These cars will be doing the Power Tour in 2012 so the handling need to figured out just in case it rains while driving across country.

 

Yes I know about high horsepower and street driving, I have seen what fools do with power on street showing off and not respecting the power and how the car / their ability to control that much power. I went to a training class on driving about 10 years ago. When I switch my vette to a twin turbo in about 3 years, I will be attending another driving class. My 17 year old son wants to drive my vette, he was informed that he needs 2 years of wheel time with a normally powered car and then driving school before he can drive my vette. To prove it we went to the mall around 6:30 AM on a Sunday morning, the ground was wet from the rain. He knows how it feels when the car has lost traction and just how much of work it is to drive my Vette. I am thinking of helping him get his own Vette / Camero, No imports or Mustangs in my house.

 

Glad to hear you have a good understanding as respect for Super High Powered Machines built and driven on the street.

I have taken rides around in low 8 second cars at the track, on the street with slicks. Riding shotgun. And they didn't ***** foot it for me.

Launched it on the street and didnt let off till around 1,000 feet or roughly a 1/4 mile later.

Very few out there can really understand just how powerful a car like that is.

Probably much like what a Jet Fighter pilot feels taking off an Navy Aircraft Carrier with his F-16.

Impressive and Awe Inspiring are a few good chosen words to begin describe that power.

Brian