[takid455]

Planning on pulling the current engine and updating some things before the warm season.
310 KRE, 474, HR (236 ish/ 242 ish @ .050, .541 lift) , bla bla bla.

Topic of interest is the affects of going to beehive style springs/ titanium retainers and lighter con rods. We know lighter stuff takes less momentum/ energy to move and should result in a livelier engine.


What have people experienced in similar before & after cases? Was it worth the expense? What would you / could have done if you were to redo if at all?

Car's purpose is corner carving and open road speed. Not much if any drag racing as suspension is kinda stiff for that. It feel the car should be more livelier in the mid to upper RPM range.

[Half-Inch Stud]

Much happiness results when you Google "Bump Steer Geometry" by Mike Savitske

[takid455]

wrong topic HIS? area of concern is internal engine components. Not suspension deisgn unless I am misreading something

[Half-Inch Stud]

Originally Posted by takid455

Planning on pulling the current engine and updating some things before the warm season.....
What have people experienced in similar before & after cases? Was it worth the expense? What would you / could have done if you were to redo if at all?

Car's purpose is corner carving and open road speed. Not much if any drag racing as suspension is kinda stiff for that. It feel the car should be more livelier in the mid to upper RPM range.

Quoted info was pretty clear to me where you will find gainns. Car will be MUCH quicker if you also review & improve the suspension geometry: bump steer & scrub radius at a minimum.

Corner carving was the big clue

[takid455]

I figured that is where you were heading. That's been addressed. I'm more focused on the engine at this point. Looking at the engine parameters themself. I pretty much know the answer and direction I will go, just looking for some feedback from those that have lightened up the internals. pre and post reactions.

[takid455]

Free beer and boobie pictures !!

[SMW]

Anytime you can make the reciprocating mass lighter the car will accelerate and decelerate quicker.

[slowbird]

Originally Posted by SMW

Anytime you can make the reciprocating mass lighter the car will accelerate and decelerate quicker.

Why? Maybe im wrong but i dont believe that.

[Dragncar]

Engines make the same power with steel rods vs aluminum rods. Aluminum rods/light pistons are just easier on parts.
If the car did accelerate quicker with light parts you would think it would decelerate quicker with heavy crank and rods once you shut the butterflies .
I doubt you could measure the difference with most combos.

[NBF823]

Weight of the crank and flywheel are where most of its at.

Things that would be nice are a short deck, small(2.75 or less) mains, etc.

There's a short deck 301turbo block with normal non301 heads here, there's a guy who used ford bearing spacers and cut the mains down to race dirt oval I believe, and there's a guy racing a grey first gen firebird with those awesome lightweight flywheel clutch combo.

I'm more interested in corner carving myself, and staying poncho isn't easy. Some small Chevy cranks are whittled down to 40lbs - my forged 3.75 is 73lbs.

The momentum of a stroker poncho might be something else. Depends where your racing too. If you got some straights, you can kill them, if your on and off the throttle and counting on engine deceleration and a rapid return to acceleration - a crank and flywheel combo that tops 100lbs is kinda not cool.

[NBF823]

Originally Posted by slowbird

Why? Maybe im wrong but i dont believe that.

If we make the whole car lighter, we can accelerate faster with the same motor - why wouldn't this hold true of the Pistons accelerating the crank?

On the other side, the heavier mass isn't going to want to stop spinning. It's like a large grinder in a shop - shut ia 2" X 10" off, and it's going to spin and spin. If you take that same grinder and throw some 1/2 X 6" wheels on it, it's going to stop considerably quicker.

It's not so much the overall weight, but more so the moment of inertia. The weight at the outside is going much faster, and there for has much more energy. This is why you see clutch combos using several small discs as opposed one large one, this way they can cut the outside weight off the flywheel and reduce its moment of inertia and have it less resistant to changes in speed.

[Tom Vaught]

Question:

How much difference do you think there is in acceleration (due to lighter weight parts) when you launch the engine at 7500 rpm, climb to 8400 rpm, drop the rpm to 7600 rpm, and then back to 8400, etc?

Weight and reciprocating mass might make a difference if you were talking about a 16000 rpm F-1 engine with a 3.5" bore, titanium rods, flat crank, that has to accelerate off the corners quickly and then reach max rpm.

So you are correct, there is a difference.

For a Pontiac guy, this discussion would be like discussing adding a tablespoon of water to Lake Michigan, did you make a change, YES, does it really matter at the end of the day? Probably not for the average pontiac racer that is running a 500+ cid engine.

Tom V.

[cosgrove]

Light weight rods pistons and crank alone = not much difference. But we don't race with just an engine. Lighter flex plate, converter, transmission internals, drive shaft, rear end parts, wheels = noticeable difference. We look at reducing rotating weight as being twice as effective as reducing non - rotating weight.

[AG]

Originally Posted by cosgrove

Light weight rods pistons and crank alone = not much difference. But we don't race with just an engine. Lighter flex plate, converter, transmission internals, drive shaft, rear end parts, wheels = noticeable difference. We look at reducing rotating weight as being twice as effective as reducing non - rotating weight.

Are you saying that facetiously or as true? The statement sounds rhetorical so I just want to know for sure.

[cosgrove]

Originally Posted by AG

Are you saying that facetiously or as true? The statement sounds rhetorical so I just want to know for sure.

I will try to be more clear. In rough terms, losing 25 pounds of rotating weight will have about the same effect as losing 50 pounds of non-rotating weight.