engine builders, balancing question

[boostedblkbeast]

I was wondering if anyone could briefly explain how to determine maximum crankshaft rmp's. I am in the process of doing a rebuild and I am getting to the point where the question of what level of balancing to have done. The machine shop offers 3 stages:
street = 0.07 grams
street/race = 0.05g
race = 0.01-3
Sorry but decimal places may be wrong, but I am sure you guys understand.
I am going with poston's gn110t cam 208/214, and would like to run about 6400 rpm's on the street and 6900-7200 rpm's at the strip. I am thinking of going with the street/race, but unsure of what the maximum rpm's I could turn would be. Or should I have them do the race, because I would still like to turn higher rpms than this, because I probably will switch cams in the future.

 

[750H.P.V6]

Boosted,

I would tell you to balance the engine as close as you can tolerance wise. I have to ask you what you're planning on running for a crank though. Is it a steel BMS or billet aftermarket piece? Also the cam you have selected doesn't have a power band anywhere near the RPM level you're talking about. Can you give some more details on the engine configuration?

Neal

 

[boostedblkbeast]

I am running 10/10 stock crank,109 block with steel 1,2,3 mains, trw 30 over pistons, stock rods, all arp fasteners, ported 8445 heads. As for the cam though, I would have to pull out the card again, because the specs might be slightly off, but I thought that it was good for the 6900 rpms. I would just like to get some rpm's out of her, just wanted to get some advice from the experienced engine builder's on this subject.

Thanks

 

[John Wilde]

That is a lot of RPM for your combination.
Your heads and cam are not ment for that range.
What are your goals with this car?
If you really want to spin the motor you should go with a roller cam. If you want to get RPM out of a standard cam as big as I have gone in a stock displacement motor is 224-224 from Precision Turbo. I loved this cam and would daily drive it if I had to. On a roller we have gone about 238 from Duttweiler on a TSM Type Motor. We do not have any times or dyno with that combination yet.

With that kind fo RPM you will need a lot of converter, I would say every bit of 4000RPM minimum!

 

[TurboDave]

Originally posted by boostedblkbeast
I am running 10/10 stock crank,109 block with steel 1,2,3 mains, trw 30 over pistons, stock rods, all arp fasteners, ported 8445 heads. As for the cam though, I would have to pull out the card again, because the specs might be slightly off, but I thought that it was good for the 6900 rpms. I would just like to get some rpm's out of her, just wanted to get some advice from the experienced engine builder's on this subject.

Thanks

You want to spin 6900 on a stock crank and stock rods???
You may want to rethink that philosophy!

 

[BOOSTBROTHER]

hey guys same question on balancing the motor I have stock 10/10 crank .30over hypers and a RJC block girdle should I have it balanced or is it worth it??????????
210/210 cam

Thanks

 

[boostedblkbeast]

My goal is to high to mid 10's, but anything faster I would be exstremely exstatic. This car is going to be a weekend warrior that will see about 4k miles a year or so. So far, it is sounding like 6900 is asking alot, would it be more realistic to say about 6400-6500 rpms. Also, I have not decided on a converter yet, but was thinking minimum of 3500 stall. Not sure if this might change some opinions, but I forgot to mention that I will be running a gen6 dfi. Thanks again for the input.

 

[John Wilde]

6400 to 6500 is closer to the ball park.
A local guy went 10.3s @ 128MPH with a full weight street car and it was not on kill.

-Stock Block
-Fast
-72injectors
-PT-70 P Trim
-Art Carr 16930 9inch converter
-218 Precision Turbo Cam
-PTE Front Mount
-I am not sure what heads he was running, damn I am getting old =(

I would still consider a different cam unless you already have the unit that you mentioned.

Who is going to be doing the tune up on the DFI?
You may want to consult with the tuner as to which parts he like in your combination.

 

[boostedblkbeast]

I am thinking of taking it to Hartline because it is about a 2 hour drive from tampa to melbourne, but all depends if I can get out of work to do that. Otherwise, their is Ramsey's here in town that I know has experience with buicks. Yes I already have the cam. I bought it a number of months back, with the intention of swapping heads and cams, but as I got into the intial tear down, I did not like what I was seeing, so from that point I decided to just do a complete rebuild.

 

[John Wilde]

If you have the chance to use Cal do it, I think that would be your best bet.

 

[postal]

Balancing:

I read some thing awhile back and I believe it was an engine building book by Grumpy Jenkins. He was the last or one of the last guys to run a small block motor in Pro Stock. Balancing a motor to with in a knats ass makes all the sense in the world, right??

But this is what he said: He said when the crank and rods are whipping around in the engine that the oil is flinging all over the place. Now this oil isn't going to be nice enough to distribute itself all nice and evenly. He said the oil itself is going to knock the balance out of wack any way so dont get too carried away with trying to make it perfect.
A gram is about what a raisin weighs. The street balancing is to .07 grams. So take a raisin cut it into 100 evenly sized pieces. Take 7 of the pieces and stick them on a rotating assembly that weighs 50 plus pounds with an uneven AND varying coat of oil on it..... going from .07 all the way down to .000 (perfect) probably would be a waste of 50 cents much less good dollars. I'm not an expert but that always stuck in my head after reading it.

The forces that try to rip a rod or crank apart is a squared function based on rpms. Double the rpm's and the forces trying to rip stuff apart goes up 4 times not 2. In simple terms it would be like saying going from a 5,000 to 10,000 rpm redline would really be like going from 5,000 to 20,000. The parts required to be reliable as the rpms increase goes nuts in a hurry. Even if you do buy the goods its not like the rpm limit all of a sudden goes through the roof. Lots of guys are exceeding your goals with out going over 6000.

HTH: Jason

 

[mayosmechanic]

Although I agree with The above.You actually take into account windage when balancing.4 grams of imbalance at 6 grand is like a sledgehammer on your rotating assembley.

 

[clemsgn]

Originally posted by John Wilde
6400 to 6500 is closer to the ball park.
A local guy went 10.3s @ 128MPH with a full weight street car and it was not on kill.

-Stock Block
-Fast
-72injectors
-PT-70 P Trim
-Art Carr 16930 9inch converter
-218 Precision Turbo Cam
-PTE Front Mount
-I am not sure what heads he was running, damn I am getting old =(

Would you be talking about Craig Brown's Grey T that he sold a couple of years ago ?

 

[GARY HARVEY]

Short Balance Story for the Buick V6

One of the group that contributed to the V6 was Smokeys. The man with Smokeys that was hands on with the development was Harry VanDriel. I gave Harry a call a few years ago asking the balance question concerning the percentage he though would work most effectively for most overall operating conditions a performance V6 would encounter? After all the questions concerning the quality of hardware was completed, Harry said in a rather matter of fact way "you really can't balance a V6 and thats why they have offset crankshafts" sounds good to me... I said. I then laid things out and found my project was balanced at 57 percent. Back to the phone and another visit with Harry. Why's this thing at 57 percent Harry, I asked.
"Not to sure, are all the static weights equal" he asks. "Yes SIR" I reply.
Then he wants to know where I bought the motor? "It's one of Spencers
Busch Series pieces" I told him. Knowing Harry I knew where this was going
and sure enough I was on the horn to Spencers engine dept. Finally located and got the balance guy on the phone "why is this engine at 57p. blah, blah"
I once again ask. Seems that after trail and error, that's where things seemed to be most effective and they played with figurers down as far as 37 percent with the short track pieces and the higher numbers with longer tracks. Back with Harry I get, "did they ever put a balance shaft in that motor?" " Later series stuff not these" I said. Well remember what I told you,
"you can't balance a V6," says Mr. VanDriel

I know this doesn't answer you question. The only thing I've done is to have everything statically equal an go with whatever the installed malory metal was when I got my little project in the begaining, cross my fingers and look to the heavens for guidance. By the way if you ever come up with a answer to this question... let me know because "you can't balance a V6."

Mr. VanDriel lives alone in Daytona, is in his late 70s and is stuck in a wheelchair full time with nerve damage, the result of being poisoned
from working on a damned old truck and breathing contaminated fuel vapors.
I will miss him when he's gone.

Gary

 

[John Wilde]

Originally posted by clemsgn
Would you be talking about Craig Brown's Grey T that he sold a couple of years ago ?

Yes Clem that would be your car.

 

[clemsgn]

Originally posted by John Wilde
Yes Clem that would be your car.

Hello John, How much do you remember about this car ? I'd like to hear anything you may remember. I know it has a billet roller cam, but is it a 218 ? By the way, the intercooler is a V-1 and the heads are M & A's

Thanks much

 

[John Wilde]

Clem,

What do you want to know?
I can probably get you intouch with Craig if you want.

 

[clemsgn]

John,

Not looking for anything specific, just any comments you may have. I actually have contacted Craig via e.mail a few times within the last year. Unfortunately I recently had low oil pressure driving home from the track. I found the oil pickup tube loose, and the bearings were wasted. I don't know if it happened gradually or was never fully tightened originally ? It has a girdle with the pickup spacer, but the bolts didn't have any loctite ? Can you shed any light on this ?

Thanks