DI, thanks for the info on the cast crank engine, I have a special one of those in the planning as we type. My scale checks show that the cast crank is 15 - 16 lbs lighter! Now add some light con rods and pistons...
DD

Doc,

With one of these 225 cranks how many rpms can you turn before it twists and breaks? Can it be repeated for very long in a street strip car? or do you have to keep tearing it down...

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Your scale is probably more accurate, I have to use the postal scale that all the e-baggers use in town (I broke it last time, weighing an 8 3/4" center section...).

That might explain why it winds up faster (a little lighter than the 6lbs...)

-D.Idiot

I have always built forged crank SL6 engines for performance uses, the only cast crank builds I have done are all stock overhauls so I do not know how much HP a cast crank SL6 is going to take.

Some things I do know: (or honestly believe)
- I have seen broken forged steel and broken cast iron SL6 cranks so it does happen.
- I have reports from reliable sources that cast crank SL6 engines have made 300 to 350 HP and stayed together.
- I am under the opinion that reducing the weight of the piston and connecting rod assemblies will reduce the stress on the crank, steel or cast.
- Good rotating assembly balancing and a good aftermarket vibration dampener prolong the life of the crank and bottom end bearings.
- A 225 SL6 with 20-25 lbs less rotating mass is going to rev-up faster and feel better at high RPMs.
I need to build a performance cast crank (low rotating mass) SL6 engine and get some data on how much better that "feel" is.
DD

I am accumulating parts for a ltwt cast crank build. I believe Superman Mike Jeffrey's first car/motor in the 10s was a cast cranker making around 350-375HP.

Lou

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Home of Slant6-powered fun machines since 1988

Hmmm... Think I'll be upgrading the compression, valves, cam, and carburation and rethinking this 'street/strip' rebuild I just did.....

-D.Idiot

Speaking of Mike Jeffery's build. I would like to know the details of his build. I took a picture of the engine in the blue 69 Valiant "Buzz'n Half Dozen. I couldn't tell much from it except he had an electric vacuum pump hooked up to the valve cover and an electric water pump. And yeah, lots on electronics in the passenger side floorboard. Nitrous controllers, delay boxes and the like. I saw it turn a 10.41 in the quarter at Houston. Extremely impressive!

He was saying something to one of the other admiring fans at the show about not having to use larger exhaust valves on a nitrous motor.

bwhitejr

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'72 Duster (Performance 360)
'83 Ramcharger (Performance 318)
'80 TrailDuster (360)
'80 D-150 Truck (See Below)
CompCams 252S, Holley 390cfm, Offy manifold
Ported, Polished and Gasket Matched
P4286813 Springs,0.040 Overbore,
0.090 Shaved Head

While the motor in Mikes car is impressive....the wiring is unbelievable!

Our mud bogger has 4 wires for the whole car....Mikes car looked like it had the wiring harness for a new Benz.....with no wrap......or ties

I also liked the stainless stepped headers.

I dont think you will get detailed info on that build......

Mike is class.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

For high HP Slants, I look for strong bottom end parts to start with.
A crankshaft the does not have deep balance drill holes right at the rod journals and connecting rods that are heavy but have small balance ends on them.

As for rotating assembly prep work, the crank gets deburred and it's "leading edges" get rounded and smooth. All the crank's oil passages get reamed-out and chamfered for better oil flow. If you start taking a lot of material off the crank, it will need to be rebalanced.

The con rods get lightened on the ends. The beam edges rounded, deburred and polished. Good quality bolts get installed and then the rods are re-conditioned.

The only other bottm end "trick" is to use an oil scraper and windage tray to keep as much oil off the crank as possible.
Although I have never tried this, I have always wanted to plug the oil squirt holes in the side of the con rods... thinking that it would reduce the amount of oil windage inside the engine.
DD

Doc,

Tell us more.

After a nice stock or mild rebuild for a one barrel you do a Super Six upgrade. (140 to 180 HP)

What is the next step up in power after that? (180 to 200 HP)

A nice small 4 barrel (390 Holley or Edelbrock 500) setup for the street?

At what HP point do you have to switch from a 2.25" pipe and go bigger?
At what HP point do you have to go to Dutra Duals or headers?

I would like to see engine build combinations including intake carb and exhaust recommendations that will make 140 HP, 160 HP, 180 HP, 200 HP, 225 HP and 250 HP. No nitrous or turbo charging please.

With all the experience you have building and racing, this type of a combination matrix would be a good guide for the rest of us especially if they use common parts that are still available. Nothing too exotic. Save that for the over 250 HP builds.

Thanks

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

From what I've seen and felt I would break the intake into these catagories and welcome input. This is based off my reading and having a 1,2 barrel and now EFI. Horsepower is estimated at crank.
For one barrel - perfectly stock to 170hp.
Super Six setup - Stock to 200hp
Four Barrel - 390 cfm 150hp to 250hp
450 cfm 180hp to 250hp
500 cfm > 200hp
I'm not saying strapping one of these on will produce these numbers I believe this is more of a guidelines knowing your goals. I'm sure some people have done more and others dramatically less. The fact remains the Slant is thristier than most people think. I know the Ford 200's don't seem to react as well as our sixes do (possible a stroke characteristic). I welcome other opinions. Next would be a table on exhaust and head modifications.

I'm sure that reciprocating mass is responsible for a lot of the stresses on a crank but what about the stresses of compression and combustion? As you build more horsepower those are, of necessity, going to increase dramatically. How do you deal with that other than to pray?

_________________
David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I notice that when folks bore and/or stroke their engines, they don't usually show the new displacement, only the change in bore/stroke. What kind of increase in displacement is usually obtained? Also, a question I've often thought about: if displacement increases by say 3%, is it fair to say it will result in about a 3% increase in output if all else is equal?

I stroked Eileen from 4.125 to 4.25 and bored from 3.4 to 3.592.
My 225 is now 258 cubes that plus 33

But most people are getting 4-10 extra cubes with normal boring sizes and it rare to find someone that has also stroked it.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

I would not say that a % change in displacement would equal that % change in. Stroke / Bore only means that you can suck in that given amount of volume. That means your are still limited by the efficency of your head/valves airflow. On top of that you got to relate that efficency to your cam and cross section of your port. I've read and learned that a smaller cross sectional port will produce more torque. I fully believe this claim to it's relativity cause I know our Indy heads have freakin huge ports.
Bren if you don't mind me asking why did you choose to stroke a motor that was already 4.125? I don't mean that demeaning at all. Also how did you guys bore the cylinders that much?
What bottom end prep has people done in the terms of shot peening, o-ring, or cyro?
Does anyone have refrence numbers for exhaust like I did for carbs?