Pontiac - Boost Turbo, supercharged, Nitrous, EFI & other Power Adders discussed here.

          
Reply
 
Thread Tools Display Modes
  #1  
Old 05-04-2020, 11:56 AM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,294
Default OVERBALANCING the parts of the engine

Back in August of 2009, I made a post about Overbalancing the parts of the engine on the forum I moderate on another website.

Because some of the info directly related to Boosted Engines I will start a thread here and welcome any new info on the subject.

Here is the post from August of 2009.

This is the Advanced Tech Section but sometimes it helps people if they understand the basics of how things work and then can apply that info to other "Advanced Tech" Racing Projects. I found this web site while looking for an answer to a "Dishing" Pistons vs Balance question on another forum.

Here is the website:

Parts 1,2, & 3 are covered in this link

http://www.eatonbalancing.com/blog/2007/11/

Parts 4 & 5 are covered in this link:

http://www.eatonbalancing.com/blog/2007/11/page/2/

This info caught my eye:

"The use of nitrous oxide, superchargers, or turbo chargers typically also requires a certain amount of overbalance. Using nitro methane in conjunction with a blower is likely the worse case scenario as cylinder pressures are extremely high under detonation which artificially increases the piston weight by a more than a normal amount. Any form of blown engine will benefit from a given amount of overbalance simply due to the weight of the piston averaging artificially heavier not only from the increase in cylinder pressure at ignition, but the increase in cylinder pressure taking place while the cylinder is also filling during the intake stroke. In this instance, the piston is averaging an overall heavier weight when running at speed. A normally aspirated engine has a given amount of pressure counterbalance in that the piston is subjected to negative pressure when the cylinder is filling but is under increased pressure during compression and ignition. If an aspirated engine is working with an extremely well designed induction system and is benefiting from a ramming effect to fill the cylinders at the upper rpm ranges, then overbalancing also helps here. And then there's the rpm factor. Balancing is linear up to a point throughout the rpm range but depending upon the masses at work within your particular assembly, there is a point in which the crankshaft rpm starts to out run the dynamics of the existing state of balance. Overbalance allows these dynamics to stay in tune or 'caught up' to the rpm's of the crankshaft. There are proprietary formulas that calculate these amounts of overbalance for all the different variables and will vary somewhat from shop to shop. Again, talk with your balance shop regarding overbalancing and determine if this would be best applied to your application."

Tom Vaught

So Mike and Eric, & Jack, any new info out there?

Have a great day and be safe out there.

TV.

__________________
"Engineers do stuff for reasons" Tom Vaught

Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
  #2  
Old 05-07-2020, 07:27 AM
taff2's Avatar
taff2 taff2 is offline
Ultimate Warrior
 
Join Date: Sep 2005
Location: South Wales in UK.
Posts: 2,172
Default

I use 2% overbalance in my current 421 turbo combo with an AllPontiac Scat 4.00" crank, and previously also used 2% in my previous high-ish 7000 rpm n/a 400 combo with a factory cast iron crank,for the very reasons Tom detailed above, the bearings always looked good. I settled on re-using the 2% figure for my turbo combo after discussing it with Tom a couple of years ago.

  #3  
Old 05-08-2020, 08:02 AM
charlie66's Avatar
charlie66 charlie66 is offline
Ultimate Warrior
 
Join Date: Dec 2004
Posts: 3,261
Default

The links dont work

__________________
My Half AN Injun.....
  #4  
Old 05-08-2020, 10:20 AM
misterp266's Avatar
misterp266 misterp266 is offline
Ultimate Warrior
 
Join Date: Jun 2005
Location: Raynham, MA
Posts: 1,790
Default Link

http://www.eatonbalancing.com/2007/1...ancing-part-1/

Is this the one Tom?

__________________
" Darksiders Rule "
  #5  
Old 05-08-2020, 02:50 PM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,294
Default

Quote:
Originally Posted by misterp266 View Post
Yes, Thanks. The Y-Block was a earlier version of the later 260/289/302 Ford engine. Some of those old-times on that board had a lot of good technical info and were willing to pass it on vs others in today's world.
Thanks for finding it.misterp266


So hopefully you will not get bashed for posting a Ford Link.

Tom V.

__________________
"Engineers do stuff for reasons" Tom Vaught

Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
  #6  
Old 05-08-2020, 07:54 PM
mgarblik mgarblik is offline
Ultimate Warrior
 
Join Date: Mar 2005
Posts: 6,035
Default

We ran 2% overbalance on the Grocery Gettet engine 541 nitrous oxide. That was the advice of my engine shop from day 1. We had excellent bearing life with those engines. The nitro engines were 4% overbalance from advice of Bill Miller, Pat Dakin (top fuel) and the Zombies. We had tons of main bearing issues due to oiling system problems not related to balance. Once the main bearings received plenty of oil at proper pressure, the overbalance was probably fine. These results are completely anecdotal though. It’s hard to produce hard data on what is the perfect balance for a race v-8.

  #7  
Old 05-09-2020, 10:55 PM
RAIV-Z's Avatar
RAIV-Z RAIV-Z is offline
Ultimate Warrior
 
Join Date: Aug 2003
Location: NH
Posts: 1,337
Default

Is there any conclusive data that really indicates overbalance helps with reliability and/or bearing life?

__________________


2023 Best ET Slip
60’ 1.224
330 3.186
1/8 4.784
MPH 152.07
1000 6.175
ET 7.347
MPH 189.92
Weight 3650

YouTube Channel --> https://www.youtube.com/channel/UC21...rWwgFdfTRqShGQ

FaceBook Group --> https://www.facebook.com/groups/220092308823847/
  #8  
Old 05-10-2020, 07:43 AM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,294
Default

Quote:
Originally Posted by RAIV-Z View Post
Is there any conclusive data that really indicates overbalance helps with reliability and/or bearing life?
Quote:
Originally Posted by mgarblik View Post
We ran 2% overbalance on the Grocery Gettet engine 541 nitrous oxide. That was the advice of my engine shop from day 1. We had excellent bearing life with those engines. The nitro engines were 4% overbalance from advice of Bill Miller, Pat Dakin (top fuel) and the Zombies.
This is all the "Data" that I need on the subject.
When Bill Miller and Pat Dakin, along with Smokey Yunick (and our own Crankshaft Technical Specialist in Ford Research) says it works, then I will not argue with them on the subject.

Post up who you think is qualified to dispute their knowledge.

Tom V.

__________________
"Engineers do stuff for reasons" Tom Vaught

Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
  #9  
Old 05-10-2020, 09:01 AM
RAIV-Z's Avatar
RAIV-Z RAIV-Z is offline
Ultimate Warrior
 
Join Date: Aug 2003
Location: NH
Posts: 1,337
Default

Quote:
Originally Posted by Tom Vaught View Post
This is all the "Data" that I need on the subject.
When Bill Miller and Pat Dakin, along with Smokey Yunick (and our own Crankshaft Technical Specialist in Ford Research) says it works, then I will not argue with them on the subject.

Post up who you think is qualified to dispute their knowledge.

Tom V.
Tom,

I’m not arguing or disputing the claim that it could be beneficial for some applications. I’m Just trying to understand if it would provide a benefit to my engine as we’ll be balancing in the next few weeks. I did mention overbalancing to my local shop to get their take. They had never seen any big performance gains. I the past, they had spoken with Crower who mentioned that they had not seen any benefits from it either.

Once we got the bearing clearance right with the 4.5 stroke we were running for the last 1.5 seasons we haven't had bearing issues either.

I have no big names to reference. I did reach out to Bill M. to get his take on my specific application though.

Ed

__________________


2023 Best ET Slip
60’ 1.224
330 3.186
1/8 4.784
MPH 152.07
1000 6.175
ET 7.347
MPH 189.92
Weight 3650

YouTube Channel --> https://www.youtube.com/channel/UC21...rWwgFdfTRqShGQ

FaceBook Group --> https://www.facebook.com/groups/220092308823847/
  #10  
Old 05-10-2020, 09:11 AM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,294
Default

Eric and Mike are very good customers of Bill Miller, so my opinion is:

If Bill Miller tells Eric and Mike that it works, and Mike posts up that it has worked on their race car for many, many passes, then why would I need to waste Mr Miller's time having him tell me exactly the same thing again.

Explain that one to me.

Tom V.

I also believe that somethings that you do for the durability of the engine, have very little effect on the engine making more horsepower. If you are asking Crower if adding the 2% gets you some hp increase I would say that you are asking the wrong question.

__________________
"Engineers do stuff for reasons" Tom Vaught

Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
  #11  
Old 05-10-2020, 03:50 PM
mgarblik mgarblik is offline
Ultimate Warrior
 
Join Date: Mar 2005
Posts: 6,035
Default

I hate to see Tom and Ed argue over this one. Hard data, that I can quantify and look at on a spread sheet or something, I just don't have. Ed, I don't know if you read the six part article Tom posted but there was some good info in there and very similar to what I read in the Sunnen engine rebuilding text book by John G Edwards, 1998. General "rule of thumb" for the past 30-40 years is high stress, high RPM V-8 engines without support for the main caps will benefit from some overbalance. BBC, and Pontiac fit that category. The question that is never really answered is how much? I have never heard of an overbalance greater than 5%. Seems like 1-2% is typical and the 4% we used I just tried because we were killing main bearings. Turns out that was not the issue but I never went back to 2%. We just left it when the bearing issue was corrected. I can't say I have ever heard of a situation where a slight overbalance hurt anything. The gains are all in bearing life, not HP IMO. So if you have zero bearing issues, I would keep doing what your doing or maybe try 1, 1.5%. Engine balance even in 2020, is still a bit of black magic I guess.

  #12  
Old 05-10-2020, 07:38 PM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,294
Default

Not really arguing with Ed, as I consider him a friend, but hate to see very busy people bothered with questions. Now if Ed bought the number of Bill Miller Rods that you guys have bought from him over the years, then maybe you should get a bit more phone time with an expert on that stuff like Mr Miller or Richard Bachelor (the Connecting Rod Expert at Carrillo Rods. I have bought several sets of his rods over the years so he will take a few minutes of his time to explain stuff to me.

Not sure what rods Ed is using in his stuff.

No hard feelings with Ed at all, just hate to see busy people bothered. I apologize Ed.

Tom V.

__________________
"Engineers do stuff for reasons" Tom Vaught

Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
  #13  
Old 05-11-2020, 05:25 PM
RAIV-Z's Avatar
RAIV-Z RAIV-Z is offline
Ultimate Warrior
 
Join Date: Aug 2003
Location: NH
Posts: 1,337
Default

On this year’s refresh, I am switching to BME rods and a shorter stroke. BME shipped the rods out mid-last week. I did end up talking to Bill today about balancing/overbalancing, he did have a few comments which led me to stick with zero balancing.

No apologies needed Tom.

__________________


2023 Best ET Slip
60’ 1.224
330 3.186
1/8 4.784
MPH 152.07
1000 6.175
ET 7.347
MPH 189.92
Weight 3650

YouTube Channel --> https://www.youtube.com/channel/UC21...rWwgFdfTRqShGQ

FaceBook Group --> https://www.facebook.com/groups/220092308823847/
The Following User Says Thank You to RAIV-Z For This Useful Post:
  #14  
Old 05-11-2020, 08:18 PM
mgarblik mgarblik is offline
Ultimate Warrior
 
Join Date: Mar 2005
Posts: 6,035
Default

Not sure what all you and Bill talked about, but I thought I would mention the tightening technique he wants used on his rods. It was different from anything I was used to, so that's why I mention. Also not sure if you are using the 396 or 426 forgings. But his big deal is dousing the serrations of the rods, and the fasteners completely in the engine oil your going to run. No assembly lube! Then snug the caps with feeler gauges between the rod pair to perfectly align them. Snug would be 20-25 ft. lbs. Then go to the final torque in one smooth single pull on the torque wrench. None of this 3-4 step stuff. I found it pretty difficult under the car with the 426 forgings going to 100 ft. lbs. Much easier on the engine stand for sure. How long are the new rods? 6.7? Best of luck with them.

  #15  
Old 05-11-2020, 09:49 PM
Tom Vaught's Avatar
Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,294
Default

Some very good info there Mike, Thanks very much.
Tom V.

__________________
"Engineers do stuff for reasons" Tom Vaught

Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward.
  #16  
Old 05-12-2020, 05:57 PM
RAIV-Z's Avatar
RAIV-Z RAIV-Z is offline
Ultimate Warrior
 
Join Date: Aug 2003
Location: NH
Posts: 1,337
Default

Quote:
Originally Posted by mgarblik View Post
Not sure what all you and Bill talked about, but I thought I would mention the tightening technique he wants used on his rods. It was different from anything I was used to, so that's why I mention. Also not sure if you are using the 396 or 426 forgings. But his big deal is dousing the serrations of the rods, and the fasteners completely in the engine oil your going to run. No assembly lube! Then snug the caps with feeler gauges between the rod pair to perfectly align them. Snug would be 20-25 ft. lbs. Then go to the final torque in one smooth single pull on the torque wrench. None of this 3-4 step stuff. I found it pretty difficult under the car with the 426 forgings going to 100 ft. lbs. Much easier on the engine stand for sure. How long are the new rods? 6.7? Best of luck with them.
Hi Mike,

Yes, we're using a 6.7 rod, Bill recommended the 396. I have used a few sets in a couple of other builds and did follow the assembly instructions from their site. Only difference with the new set is the torque, 100ft/lb instead of 75.


(1) Disassemble each rod. Blow the parts clean of contaminants with shop air. Pay special attention to the serrated mating surfaces and rod bolt holes. If the connecting rod or bolts must be cleaned, use only a solvent bath. DO NOT use any aqueous cleaning process, aerosol "brake clean" products, MEK, acetone, lacquer thinner or any caustic cleaning process, such as "hot tanking", as all of these will cause the connecting rod bolts to corrode which may lead to stress-corrosion cracking and bolt failure.

(2) If serrated surfaces are slightly damaged during installation or usage they may be dressed with a small, jeweler's file.

(3) Apply lubricant to all serrated surfaces, all bolt threads, all washer seats in rod caps, all threads in the rod's big end and both sides of washers

(4) Install washers on the bolts with the chamfered, inside-diameter toward the bolt head.

(5) Assemble the rod cap to the beam and lightly snug the bolts making sure that large chamfer on the rod faces the crankshaft cheek.

(6) As an aid for cap alignment and bolt tightening, two feeler gauges of the proper thickness should be inserted between the pair of rods at the parting lines.

(7) Tighten all rod bolts to the torque specifications listed below in one smooth pull. Do not tighten in steps or increments. Doing so will produce improper bolt elongation and reduce clamping force.

__________________


2023 Best ET Slip
60’ 1.224
330 3.186
1/8 4.784
MPH 152.07
1000 6.175
ET 7.347
MPH 189.92
Weight 3650

YouTube Channel --> https://www.youtube.com/channel/UC21...rWwgFdfTRqShGQ

FaceBook Group --> https://www.facebook.com/groups/220092308823847/
  #17  
Old 05-13-2020, 06:12 AM
taff2's Avatar
taff2 taff2 is offline
Ultimate Warrior
 
Join Date: Sep 2005
Location: South Wales in UK.
Posts: 2,172
Default

Pretty much identical procedure for my Brooks B2 ali rods. These are MUCH thicker/bigger than the 396 rods I had, but the surface finish and 'feel' wasn't close to the BME's.

  #18  
Old 05-14-2020, 09:18 PM
mgarblik mgarblik is offline
Ultimate Warrior
 
Join Date: Mar 2005
Posts: 6,035
Default

Quote:
Originally Posted by RAIV-Z View Post
Hi Mike,

Yes, we're using a 6.7 rod, Bill recommended the 396. I have used a few sets in a couple of other builds and did follow the assembly instructions from their site. Only difference with the new set is the torque, 100ft/lb instead of 75.


(1) Disassemble each rod. Blow the parts clean of contaminants with shop air. Pay special attention to the serrated mating surfaces and rod bolt holes. If the connecting rod or bolts must be cleaned, use only a solvent bath. DO NOT use any aqueous cleaning process, aerosol "brake clean" products, MEK, acetone, lacquer thinner or any caustic cleaning process, such as "hot tanking", as all of these will cause the connecting rod bolts to corrode which may lead to stress-corrosion cracking and bolt failure.

(2) If serrated surfaces are slightly damaged during installation or usage they may be dressed with a small, jeweler's file.

(3) Apply lubricant to all serrated surfaces, all bolt threads, all washer seats in rod caps, all threads in the rod's big end and both sides of washers

(4) Install washers on the bolts with the chamfered, inside-diameter toward the bolt head.

(5) Assemble the rod cap to the beam and lightly snug the bolts making sure that large chamfer on the rod faces the crankshaft cheek.

(6) As an aid for cap alignment and bolt tightening, two feeler gauges of the proper thickness should be inserted between the pair of rods at the parting lines.

(7) Tighten all rod bolts to the torque specifications listed below in one smooth pull. Do not tighten in steps or increments. Doing so will produce improper bolt elongation and reduce clamping force.
So your that one guy who reads the instructions!! That's the ones. I didn't mean to implicate they were top secret or anything. I had always been taught the multi-step procedure. Learn new stuff every day. Good luck this year. I hope everyone is racing soon. The Pontiac Nationals may be one of Norwalk's first events at this rate.

The Following User Says Thank You to mgarblik For This Useful Post:
  #19  
Old 05-15-2020, 12:53 AM
blueghoast's Avatar
blueghoast blueghoast is offline
Ultimate Warrior
 
Join Date: Jan 2011
Posts: 2,396
Default

Quote:
Originally Posted by mgarblik View Post
I hate to see Tom and Ed argue over this one. Hard data, that I can quantify and look at on a spread sheet or something, I just don't have. Ed, I don't know if you read the six part article Tom posted but there was some good info in there and very similar to what I read in the Sunnen engine rebuilding text book by John G Edwards, 1998. General "rule of thumb" for the past 30-40 years is high stress, high RPM V-8 engines without support for the main caps will benefit from some overbalance. BBC, and Pontiac fit that category. The question that is never really answered is how much? I have never heard of an overbalance greater than 5%. Seems like 1-2% is typical and the 4% we used I just tried because we were killing main bearings. Turns out that was not the issue but I never went back to 2%. We just left it when the bearing issue was corrected. I can't say I have ever heard of a situation where a slight overbalance hurt anything. The gains are all in bearing life, not HP IMO. So if you have zero bearing issues, I would keep doing what your doing or maybe try 1, 1.5%. Engine balance even in 2020, is still a bit of black magic I guess.



So what was your issue with killing the bearings if I might ask. Thanks

GT.

  #20  
Old 05-15-2020, 09:49 AM
mgarblik mgarblik is offline
Ultimate Warrior
 
Join Date: Mar 2005
Posts: 6,035
Default

I don't want to derail the thread. Very briefly, The 90% nitro engine needed huge main clearances, .0065-.007", and 200 PSI down track oil pressure to survive. Also internal main oil galleries had to be gun drilled larger. 42 GPM oil pump Stock Pontiac, is around 7 GPM.

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:47 PM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017