Light weight parts vs heavy parts

stock eliminator · 01-12-2010, 09:40 PM

I was wondering what e.t. difference there is between light vs. heavy parts. For example stock pistons are heavy but CP or other brands are extremely light. Has anyone ran heavy then put in light ones and seen e.t. differance??

Kenny Wigington · 01-12-2010, 09:55 PM

You may not get much for answers to that, publicly, maybe some in a PM though....

stock eliminator · 01-12-2010, 10:26 PM

I figured it would be a touchy subject

Ed Fernandez · 01-12-2010, 10:30 PM

Check out [email]cheating101@$creweveryoneel$e.com

Adger Smith · 01-13-2010, 12:25 AM

Hey Ed,
that link doesn't work for me... :~)
must be a few too may $$$'S in it.. ;~)

james schaechter · 01-13-2010, 05:55 AM

This isn't actually controversial.

There are specs on piston types and rods for weights,etc. In general, If it moves, lighter is better. I don't know if anyone could actually tell you how much better it was, but the piston example is a good one. The replacement stuff has a lot of benefits besides weight too. Better quality all of the way around. I would say that if you are building a stocker engine or any quality race engine, the core components need to be the highest quality and the lightest you can legally run and afford.

Even in drivetrain, every real serious effort points to lighter stuff. Alum shocks, lighter axles, lighter spools and gear, transmission parts, lighter clutches, etc. I am sure that there is someone out there that can point to an example to the contrary, but if you walk around the pits and look at cars, talk to racers, you will see what I mean.

mannymen · 01-13-2010, 02:00 PM

From light to heavy also works. It's all trial and error on the dyno

Chris "drooze" Wertman · 01-13-2010, 03:36 PM

Very true, especially on smaller (gp bikes) added weight in certain areas keeps rotating mass inertia up, and will stabilize across accel ranges, sometimes, sometimes its better to be heavier.

In my experience on a dyno with very small very fast engines it best to reduce any "long" mass, pistons, rods etc. If you keep the roating mass closest to its cenerline the best obviously

Quote:

Originally Posted by mannymen

From light to heavy also works. It's all trial and error on the dyno

Greg Reimer 7376 · 01-15-2010, 11:18 AM

One of the main advantages to light pistons,pins,etc. are found in the area of parts reliability.A heavy piston is harder to accelerate from either TDC or BDC. The rod likes to stretch more with a heavy piston and pin,(actually the rod DOESN'T like to stretch,but has to anyway).At the conclusion of the exhaust stroke, ther is no plug of compressed gas pro-viding resistance to the piston's headlong plunge up the cylinder toward the open valves in the head. The two rod bolts have the unenviable job of stopping the rod,piston,pin and rings from continuing out the top of the cylinder bore.When rod failure occurs, it usually happens on the exhaust stroke,hence two bent valves you usually find in the aftermath.NHRA has a minimum weight spec for the combined piston,pin,locks,rings and rod, and I found it to be rather generous. The minimum for a 327 is around 1200 grams, an OEM cast piston,stock pin, rings and rod (no bearing) is around 1402 grams. The legal weight allowance would also allow you to rebalance the crank by removing a lot of weight from the counterweights, making for a much lighter rotating mass.Any combination that would benefit more by a light flywheel as in a stick class, would like a light assembly as well.As to the drive train, in my earlier days with my Chevelle, I set the rear end up with a Moroso Brute Strength posi and OEM axles. No parts failures, but later I got a spool,billet axles, and a C clip eliminator kit. That whole assembly was several pounds lighter. I translated that into less inertia loads on everything else, and the car was consistantly .08-.10 quicker in 60 foot and subsequent ET's.Talk to Dave Smith at Pro Trans for an opinion of what aluminum drums and light trans parts will do for your combination. I'd rather put the weight back in the weight box rather than everyplace else. A further note, I used to race a 409 Chevy, and the stock forged piston,made by TRW, weighed 1040 grams with no pin, no rings or locks. That thing was like a forged aluminum flower pot!!!

01-12-2010, 09:40 PM	#1
stock eliminator Junior Member Join Date: Apr 2008 Location: Kearney Nebraska Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Light weight parts vs heavy parts I was wondering what e.t. difference there is between light vs. heavy parts. For example stock pistons are heavy but CP or other brands are extremely light. Has anyone ran heavy then put in light ones and seen e.t. differance??

01-12-2010, 09:55 PM	#2
Kenny Wigington Senior Member Join Date: Sep 2004 Location: Cumming,Ga. USA Posts: 967 Likes: 36 Liked 60 Times in 12 Posts	Re: Light weight parts vs heavy parts You may not get much for answers to that, publicly, maybe some in a PM though.... __________________ 2894 STK Last edited by Kenny Wigington; 01-13-2010 at 03:32 PM.

01-12-2010, 10:26 PM	#3
stock eliminator Junior Member Join Date: Apr 2008 Location: Kearney Nebraska Posts: 24 Likes: 0 Liked 0 Times in 0 Posts	Re: Light weight parts vs heavy parts I figured it would be a touchy subject

01-12-2010, 10:30 PM	#4
Ed Fernandez Veteran Member Join Date: Nov 2001 Location: NOO JOISEY nexta NOO YAWK Posts: 5,879 Likes: 38 Liked 100 Times in 45 Posts	Re: Light weight parts vs heavy parts Check out [email]cheating101@$creweveryoneel$e.com __________________ Former NHRA #1945 Former IHRA #1945 T/SA

01-13-2010, 12:25 AM	#5
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Light weight parts vs heavy parts Hey Ed, that link doesn't work for me... :~) must be a few too may $$$'S in it.. ;~) __________________ Adger Smith (Former SS)

01-13-2010, 05:55 AM	#6
james schaechter VIP Member Join Date: Dec 2004 Location: Cumming GA Posts: 1,985 Likes: 1,277 Liked 1,424 Times in 294 Posts	Re: Light weight parts vs heavy parts This isn't actually controversial. There are specs on piston types and rods for weights,etc. In general, If it moves, lighter is better. I don't know if anyone could actually tell you how much better it was, but the piston example is a good one. The replacement stuff has a lot of benefits besides weight too. Better quality all of the way around. I would say that if you are building a stocker engine or any quality race engine, the core components need to be the highest quality and the lightest you can legally run and afford. Even in drivetrain, every real serious effort points to lighter stuff. Alum shocks, lighter axles, lighter spools and gear, transmission parts, lighter clutches, etc. I am sure that there is someone out there that can point to an example to the contrary, but if you walk around the pits and look at cars, talk to racers, you will see what I mean. __________________ James Schaechter 3163 STK

01-13-2010, 02:00 PM	#7
mannymen Senior Member Join Date: Apr 2003 Posts: 728 Likes: 5 Liked 13 Times in 7 Posts	Re: Light weight parts vs heavy parts From light to heavy also works. It's all trial and error on the dyno __________________ N/A

01-15-2010, 11:18 AM	#9
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,132 Likes: 172 Liked 698 Times in 216 Posts	Re: Light weight parts vs heavy parts One of the main advantages to light pistons,pins,etc. are found in the area of parts reliability.A heavy piston is harder to accelerate from either TDC or BDC. The rod likes to stretch more with a heavy piston and pin,(actually the rod DOESN'T like to stretch,but has to anyway).At the conclusion of the exhaust stroke, ther is no plug of compressed gas pro-viding resistance to the piston's headlong plunge up the cylinder toward the open valves in the head. The two rod bolts have the unenviable job of stopping the rod,piston,pin and rings from continuing out the top of the cylinder bore.When rod failure occurs, it usually happens on the exhaust stroke,hence two bent valves you usually find in the aftermath.NHRA has a minimum weight spec for the combined piston,pin,locks,rings and rod, and I found it to be rather generous. The minimum for a 327 is around 1200 grams, an OEM cast piston,stock pin, rings and rod (no bearing) is around 1402 grams. The legal weight allowance would also allow you to rebalance the crank by removing a lot of weight from the counterweights, making for a much lighter rotating mass.Any combination that would benefit more by a light flywheel as in a stick class, would like a light assembly as well.As to the drive train, in my earlier days with my Chevelle, I set the rear end up with a Moroso Brute Strength posi and OEM axles. No parts failures, but later I got a spool,billet axles, and a C clip eliminator kit. That whole assembly was several pounds lighter. I translated that into less inertia loads on everything else, and the car was consistantly .08-.10 quicker in 60 foot and subsequent ET's.Talk to Dave Smith at Pro Trans for an opinion of what aluminum drums and light trans parts will do for your combination. I'd rather put the weight back in the weight box rather than everyplace else. A further note, I used to race a 409 Chevy, and the stock forged piston,made by TRW, weighed 1040 grams with no pin, no rings or locks. That thing was like a forged aluminum flower pot!!!