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Discussion Starter #1 (Edited)
Here are the rules...

Must be iron heads and block, does not have to be stock...

Any aluminum intake manifold...

Unlimited cubic inches...

One 2-barrel carburetor only of stock production type. Must be Rochester or Holley with choke horn unaltered...

No alcohol allowed...

Must use stock HEI ignition with no MSD style system...

Anything other than that, have fun...


I was thinking 434 cubic inches in a Dart block, Dart heads, Dart high rise intake, 500 CFM Holley hogged to the max with an adapter plate to go on the intake...
 

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The two barrel limits the breathing of a big inch engine. This will lead to poor action by said engine.
 

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Vortec 350 punched to 383 with GMPP TBI intake and 46mm TB with Proper chip and fuel regulator. 315hp(ish) and 400-450ft/lbs(ish).

Why would you want a card for a trail rig? So when you get a bad angle you'll stall?
 

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what about smaller cubes and a turbo? or is that just too much? what kind of spec class racing is it?
 

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From the restrictions he said im guessing its going in some type of of dirt/circle/etc track car for a certain class thus the restrictions, I know the local dirt track around here has a class that has those restrictions.
 

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Discussion Starter #6
The two barrel limits the breathing of a big inch engine. This will lead to poor action by said engine.
That is the only thing that worries me, BUT we are running engines in pavement cars well over 500 horse with a 500 CFM carb though, and a 500 Holley can be cut alot bigger...

Vortec 350 punched to 383 with GMPP TBI intake and 46mm TB with Proper chip and fuel regulator. 315hp(ish) and 400-450ft/lbs(ish).

Why would you want a card for a trail rig? So when you get a bad angle you'll stall?
what about smaller cubes and a turbo? or is that just too much? what kind of spec class racing is it?
Read below, has to be within those specific rules above...

From the restrictions he said im guessing its going in some type of of dirt/circle/etc track car for a certain class thus the restrictions, I know the local dirt track around here has a class that has those restrictions.
Yes, it is a Hobby Stock class and I was looking at how far I could push the rules in the class into the gray area and thought I would give some of the engine guys here a chance to see what they say...
 

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99-2000 iron head LQ4 6.0L port heads, stroke to 408ci, cam, alu carb intake, and front mount distbutor setup. 4bbl carb. adapter to two if you have to have it.

Not sure what it would make with a 2bbl carb.
 

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Discussion Starter #8
99-2000 iron head LQ4 6.0L port heads, stroke to 408ci, cam, alu carb intake, and front mount distbutor setup. 4bbl carb. adapter to two if you have to have it.

Not sure what it would make with a 2bbl carb.
I had thought about a LS engine but I am thinking the front mount distributor may be a little too far into the gray area for them...
 

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factory front mount distributors are available for the LS engine... how would it be stretching it?

my idea for the engine would be different, i guess.

short stroke, large bore, like 3.250 x 4.125 for 347 cid.

the shorter stroke should keep the piston from wanting to be beaten at lower RPM, allow for a larger column of air with less depression pulling on it until piston speed equals that of a longer stroke engine..., so it wont come into its hp peak until later in the rpm range.... but it should respond faster and allow a lot bigger cam.
 

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I had thought about a LS engine but I am thinking the front mount distributor may be a little too far into the gray area for them...
Why would it be gray. Its a distributor and even has provision for a mechanical fuel pump. The front drives are offered by GMPP and have GM part numbers. Does use a Ford disturber IIR. :laughing:

But be hard to find the iron heads as they are getting old 99-2000. The good thing is no one wants them.
 

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Is there a CR rule? Some 2bbl limited late models around here are running 12.5 to 1. Cam ground to suit intake and exhaust system.

The idea of high compression is to squeeze whatever does get thru a 2bbl in combination with the camshaft, not a high RPM combination but lots of low end. Comp Cams had this stuff covered at one time.

Another avenue is lots of non-wing sprint cars are 360 ci with a carb, making decent power.

sprntpshr
 

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no CR rule...

here is my take on it..
first, a 347, designed to make lots of rpm....
then, a 414 incher...

look at the numbers, and figure out which one will make more useable power for the application... ie; a high winding motor with less low end torque will stick to the track better as it doesnt blow the tires off half way through the turn...
 

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based on all the other variables besides stroke and CR...

the engine with more CID will require more CSA, or sectional area at the pushrod pinch on the cylinder head. the 414 is almost undoable without lowering rpm.
 

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iF YOU LOOKING TO STAY WITH A 23* HEAD, AND ARENT ALLOWED A rr, sorry about the caps. If you Allowed RR I think Proaction did a cast iron in a RR . If you cant use a RR, then Your limited to a 230cc intake port,or maybe a RHS 235 with some work. Problem is as said above CSA is the restriction . The entire induction system with be a choke point. What are the rules on th eblock ? can you run a raised cam spread pan rail ?
 

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grumpy,
what program is that?
 

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It all comes down to the fund$ available.
I agree with Grump, but I would go to a 4.180+ bore, and lengthen the rods to 6.350. Piston, pin and ring package will be very important, and going with the smallest journals you can. All in keeping the parasitic losses to a minimum.
Valve train will be another IMPORTANT area. Being this thing is restricted at the top by a 2 barrel carb, it will need some special, high velocity valve events to optimize performance.
Chad Sperier in Kansas does some nice CNC iron RHS heads.
 

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i like that it shows piston speed. would an engine with a lower piston speed # have less parasitic loss?
if this is true i can now see why building a smaller short stroke engine would be better for this application.
 
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