blowers hard on main bearings?

[cyclone]

is it a commonly held theory that roots blowers are hard on main bearings? i hear it quite often and my last two motors seem to back of this idea. And if its true, what causes the extra stress on the bearings? tension on the snout of the crankshaft from the blower belt?

[BUSBY]

is it a commonly held theory that roots blowers are hard on main bearings? i hear it quite often and my last two motors seem to back of this idea. And if its true, what causes the extra stress on the bearings? tension on the snout of the crankshaft from the blower belt?
Yup ... that's why they make the crank support ... you crank will whip with the added belt tension ... you have to remember that they were not originally designed to have that belt drive attached ...
When you bring your stuff over, bring the bearings for inspection ... I have a few sets from when I did Ron's dealio ... we'll compare ...
BB

[Speedin' Ian]

On my last blown deal the bearings looked great, and I'm assuming that's because we always had the proper amount of slack in the belt. I would say the majority of blown motors I see have the belt too tight.

[BUSBY]

On my last blown deal the bearings looked great, and I'm assuming that's because we always had the proper amount of slack in the belt. I would say the majority of blown motors I see have the belt too tight.
Well ... Mike's problem is that he's in a Jet and he has the "hammer down" effect caused by his right foot :D
It's like making dyno pulls consistantly.

[Blown 472]

Did you pound the mains out? I know mine is hard on rod brgs.

[Huffer]

ALWAYS SEEMED TO BE HARD ON THE ROD BRGS,NOT SO MUCH ON THE MAINS.LEAVE THAT BELT LOOSE!THAT'S WHAT THEY MAKE THE (H) BRGS FOR!

[UBFJ #454]

Don't ya think there's more to main bearings (and for that matter rod bearings) wear with a blower (what kind ... simple roots, Hi-Helix, screw ... ) than just the front blower drive? Harmonics from the blower drive are one thing ... Amount of boost and what it's driving (jet vs. v-drive ... or, on asphalt ... instantaneous Tq and/or the lack of It ... Abrupt Rotational Motion) also comes into significant play in terms of lower end Life ...
Reading bearings of a Competion Motor (blower, N/A, N/A with n2o ... ) tells alot as they all 'tell their tales' ... Just have to 'Look & Read' ... where are the scuff marks on the bearings/journals, plus 'everything else', etc..

[BUSBY]

Yup ... there is a story to be read with bearings ... If he's running it hard as we are ... he will have hammered out the lowers and the #2 main should have wear onboth upper and lower without a crank support.
We're gonna measure 'em and see how hard he running ...
Mike shouldn't have much harmonics ... it's all balanced internally and he runs a balancer as well ... right Mike?
Unless he had a poor balance job :idea:

[UBFJ #454]

Brian -
Ain't Criticizing AnyOne for what their doing, or not doing ... Just Reminding People that they could Benefit from 'Paying Attention To Details' ... The Motor will tell you what's going on ... If You'all Will 'Just Look ... See ... and ... Listen' ...' And .....
In my opinion (As Humble as It Never Is), Too Many people pay Too Much Money For Junk ... They Really need to understand what's going on and not listen to what their 'Told' and spend their money where they understand what their getting ..... Or, Not ...
Exchange of Information on the Forums, such as here, Helps Everyone (At Least In The First and, maybe, Second Degree) ... I Think ... I'm Hoping.

[cyclone]

Yup ... there is a story to be read with bearings ... If he's running it hard as we are ... he will have hammered out the lowers and the #2 main should have wear onboth upper and lower without a crank support.
We're gonna measure 'em and see how hard he running ...
Mike shouldn't have much harmonics ... it's all balanced internally and he runs a balancer as well ... right Mike?
Unless he had a poor balance job :idea:
Yes on the internal balance and balancer. i watched jimmy @ Dougan's weigh and balance my rods, pistons, pins and crankshaft. Did an excellent job. I'm extremely careful with the belt tension. Haven't seen my current set of bearings yet so i cant tell ya how good/bad they look.
We should be good to go for later next week Brian. Ray said he'd be done with the parts no problem.

[revndave]

I have never had any main bearing problems with my blower motors.Dropped some valves but thats it.

[BUSBY]

Well ... for what it's worth ... I've gone through a couple (or should I say a couple dozen) of really fast BGJ, BFJ & BAH motors in my time ... all have gotten into 7's & low 8's in the 1/4 ...
Mains sure took a beating ... but these guys are pushing them REALLY HARD ... some Ford, most Chevy ...
but maybe that's the problem ... Me ...
(but at least all of my motors have taken their boats into those numbers :D )

[cyclone]

how many motors you think you've put together in your garage brian?

[bigkatboat]

I've had blown GAS FLATBOTTOMS go into the 7'0's WITHOUT bearing failure! Infact the motors lasted ALL SEASON, with just valve spring replacement, so it sounds like you are using too much bearing clearance. It might just be the oil that you use, but if your 40wt oil cann't support 2.5 on the rods, then that's the problem. From a former GM Delco Moraine Engineering Corp. Engineer (engine bearings division). These boats ran back in the 1990's. PS, 50wt holds the wet sump motors back too much, as you might have found out. Dry sump is an other story!

[BUSBY]

how many motors you think you've put together in your garage brian?
Oh ... 1 or 2 maybe ... but what do I know ... :hammerhea

[BUSBY]

I've had blown GAS FLATBOTTOMS go into the 7'0's WITHOUT bearing failure! Infact the motors lasted ALL SEASON, with just valve spring replacement, so it sounds like you are using too much bearing clearance. It might just be the oil that you use, but if your 40wt oil cann't support 2.5 on the rods, then that's the problem. From a former GM Delco Moraine Engineering Corp. Engineer (engine bearings division). These boats ran back in the 1990's. PS, 50wt holds the wet sump motors back too much, as you might have found out. Dry sump is an other story!
We never spoke of bearing failure ... just wear (after running all season)
Thanks for the .02 though ...

[DeputyDawg]

I think a lot of blown river/lake rods as well as blown street cruisers suffer from detonation that goes unnoticed and that will kill main bearings. Ever ran your blown boat or street rod around for a season or even a month or two and then for whatever reason you decide to remove the crank pulley only to find that it is damn near impossible to get it off? Guess what, detonation can do this too. It also seems to me that blown gas motors are harder on bearings than alky motors which I have always thought was because of the tune up being harder to nail on the gas motor since alky is so forgiving. I have never run a drag boat so I may be way off track here but I do believe that even mild detonation is a lot of the problem.

[BUSBY]

I think a lot of blown river/lake rods as well as blown street cruisers suffer from detonation that goes unnoticed and that will kill main bearings. Ever ran your blown boat or street rod around for a season or even a month or two and then for whatever reason you decide to remove the crank pulley only to find that it is damn near impossible to get it off? Guess what, detonation can do this too. It also seems to me that blown gas motors are harder on bearings than alky motors which I have always thought was because of the tune up being harder to nail on the gas motor since alky is so forgiving. I have never run a drag boat so I may be way off track here but I do believe that even mild detonation is a lot of the problem.
Oh ... I'm in total agreement with you here ... Blown Gas is soooooo much harder to tune than blown Alky ... and much more un-forgiving ...
If it were up to me ... I would never have to tune a blown gas dealio again ... but the chances of that are slim to none ...
Everyone should switch to alcohol ... it would make my life easier for those who I tune for ... and it's only $2.20 per gallon ... why would you want to pay $5.75 per gallon for C16 to only run slower? :hammer2:

[disco_charger]

I think a lot of blown river/lake rods as well as blown street cruisers suffer from detonation that goes unnoticed and that will kill main bearings. Ever ran your blown boat or street rod around for a season or even a month or two and then for whatever reason you decide to remove the crank pulley only to find that it is damn near impossible to get it off? Guess what, detonation can do this too. It also seems to me that blown gas motors are harder on bearings than alky motors which I have always thought was because of the tune up being harder to nail on the gas motor since alky is so forgiving. I have never run a drag boat so I may be way off track here but I do believe that even mild detonation is a lot of the problem.
When we redid our poor little blower motor 2 seasons ago, the rod bearings were hammered. I attributed this to the last guy running 15% over with pump gas closed chambers, 8.5-1 pistons, and a constant need to prove to the world that the boat "get's up and boogies!" I run AV just in case I get a wild infection of "the boogies." :idea:

[UBFJ #454]

"and it's only $2.20 per gallon ... why would you want to pay $5.75 per gallon for C16"
And WHERE, pray tell, do you find either that cheep these days?

[Unchained]

Oh ... I'm in total agreement with you here ... Blown Gas is soooooo much harder to tune than blown Alky ... and much more un-forgiving ...
Again this subject comes up, so again I'll ask the question, Why don't you use an O2 sensor to tell you the EXACT air/fuel ratio ?
There's a few of them out there now............a few hundred million in use every day.
There's no guesswork involved with an O2 sensor. The A/F ratio is either right or it's not.
The whole setup including datalogging of A/F, manifold pressure, rpm, and EGT is $ 589.00 which includes all the sensors.
http://www.innovatemotorsports.com/xcart/customer/home.php?cat=248
Supertuner Kenny Duttweiler endorses this unit as the one they use on every engine they dyno.
Don't tell me, let me guess, " my engine is so powerful that it would blow that O2 sensor right out of the header " :rolleyes: :D

[BUSBY]

Umm ... we do use data loggers including EGT's ... and I know what an O2 sensor is and how it works ...
thanks for your input, but tuning a gas motor is harder than tuning an alcohol motor.
when you change the main jet on an alcohol injector ... you can change it by .010" and see a small change ... on a gas setup, if you do that, you'll be WAY off ... you tune in increments of .002" with gas not .010" ... that makes the margin for tuning a little bit smaller and a little bit harder, wouldn't you agree?
but what do I know ... I'm in Real Estate ... :hammer2:

[BUSBY]

"and it's only $2.20 per gallon ... why would you want to pay $5.75 per gallon for C16"
And WHERE, pray tell, do you find either that cheep these days?
Our Methanol ... So Cal Fuels, in Downey - had to check the receipt this morning to verify, sorry I was off ... it was $2.25/gal ... it must have gone up .05 here lately ...
Our C16 ... we receive VP direct, 55 gallon drums.

[BUSBY]

Again this subject comes up, so again I'll ask the question, Why don't you use an O2 sensor to tell you the EXACT air/fuel ratio ? :
Refresh my memory ... have we spoke before about this? If so, I don't remember ...
Don't tell me, let me guess, " my engine is so powerful that it would blow that O2 sensor right out of the header " :rolleyes: :D
??? where did this come from ??? :squiggle: :confused:
As I said before in a lot of other posts ... don't listen to me, I've been called looney ... and I'm just a guy in Real Estate ... so I probably don't know anything ... you should listen to "Supertuner Kenny" more than me ...

[Unchained]

??? where did this come from ??? :squiggle: :confused:
Just some sarcastic midwest humor.
" As I said before in a lot of other posts ... don't listen to me, I've been called looney ... and I'm just a guy in Real Estate ... so I probably don't know anything ... you should listen to "Supertuner Kenny" more than me ...
I'm in real estate too. A developer wannabe.
Here's my site,
www.chprop.com
I do listen to how the experts do it.
Never too old to learn you know.
I'm just puzzled by the reluctance of the drag boaters to use proven tuning methods / engine management systems that others have been using for years.
I haven't seen an O2 sensor or an EFI system on a drag boat yet.
I've seen a lot of them go down the track with a black cloud following them though.

[BUSBY]

I'm in real estate too. A developer wannabe.
Here's my site,
www.chprop.com
I do listen to how the experts do it.
Never too old to learn you know.
I'm just puzzled by the reluctance of the drag boaters to use proven tuning methods / engine management systems that others have been using for years.
I haven't seen an O2 sensor or an EFI system on a drag boat yet.
I've seen a lot of them go down the track with a black cloud following them though.
It's all good ... engine management is the way to go ... I don't think an O2 sensor would be used in Drag Boat situations.
O2 sensors are galvanic batteries that wouldn't hold up too well with the vibrations & temps. In normal vehicles (well at least the ones we used to work with) O2 sensors were hit and miss ... and if there is (or was) a problem) it would set a code and change a fuel curve, not damage any parts.
With all of the fuel still burning in the exhaust due to different timing curves ... the reading would be innaccurate, therefore pyrometers are used more. They will tell the temperatures of the exhaust rather than a .4 - .6 voltage reading being sent to a computer that tells the injectors to pulse more or less ...
In the drag boat (or drag racing world in general) world, EFI will probably never make it to the PRO classes ... humans read the data and make the adjustments ... there is too much money IMO at risk to trust a O2 sensor to set my fuel curve ... an o2 sensors failure rate is MUCH higher than pyrometers ...
And I agree, no-one is ever to old to learn, myself included ... but again, I'm a little looney! :D

[BUSBY]

but this is a different conversation ... back to Mike's bearing question ...
bearings are there to take the beating ... that is what they are designed to do. They are engineered to wear and show signs of what is happening. Now, you take the bearings out and "read" them as Jak has said.
If you are running hard, your piston and rod have a lot more "down force" which will push harder on you bearings ... if you are running steel rods, your reciprocating weight will be even higher than aluminium rods ... therefore you will have bearings taking more abuse ...
to sum it up ... you have to think about the basics here ... you have an explosion happening on top of the piston that pushes your rod down. When it pushes that rod down ... it turns a crank ... there will be a certian amount of wear happening ... you need to look at a lot of different things as well though ... like "how hard is it for the crank to turn & how much force is needed to keep it going" ... there are about 25-30 things I could list ... but why? That'll just bring up more questions ... it's a long, long subject ...
There you have it, my Sunday morning soap box speech ...
Off to take out Ron's motor and install another ... :D

[DeputyDawg]

Hey unchained, your boat runs very well and you have worked hard to make it all work that way. I know you run an O2 sensor with your deal and you just can't understand why everybody else doesn't, but most guys who are running lake/river rod s that occaisionally run at the track are running water injected headers which I believe makes it impossible to run an O2 sensor, right? I think most guys try to get away with as few electronics as possible on a boat because water and electronics don't mix. And when it comes to drag boats I agree with BUSBY in that most folks are not going to trust an O2 sensor to do their tuning. Hell, I don't think you'll see very many of them in NHRA either with the exception of the rice burner Fast and Furious wannabes!

[UBFJ #454]

Mark ... Everyone Else -
Rather than Hi-Jack this Thread let's start a New One in "Gear Heads" dealing with "EGT, O2 (A/F) Tuning, Etc." ...

[Unchained]

The O2 sensor is really only required for tuning.
Once you know where your tune is you can certainly take it out.
My point is without it you don't know what your mixture ratio is.
Trial and error has become the standard method.
The O2 sensor would only have to be in all the time for a closed loop setup and I agree that would never be practical for a racing application.
I haven't run closed loop yet. I adjust the fuel maps with the readings from the O2 sensor and that's all I use it for.
Actually running closed loop only fine tunes the mixture within a small percentage while the engine is running. The fuel maps have to be set real close to start with.
No insults intended but you have some misconceptions about EFI / engine management / O2 sensors.
I disagree with your assumption about the future of EFI for racing.
Once a few more people run it and the masses see the huge advantages they will change over.

[cruser]

The rules from the club that runs the races up here do not allow using electronic device to automatically adjust (tune) the motor. Until this rule is modified, closed loop EFI will not find it's way on to the race track at CDBA races. At least those were the rules when I checked last year.

[Cs19]

Michael Garret, just build an N/A motor and you wont have this problem. :D
Hopefully see you in Oct.

[steelcomp]

The block and crank you're running also have a lot to do with bearing life. Bowtie/ Merlin blocks are far more rigid. Less cap walk and block flex. Same with aftermarket cranks. Critical align bore will help.
Busby's right in that the bearings are there to take the pounding, and will tell you ecxactly what you need to know. Also a good reason for running aluminum rods, as they help absorb a lot of that shock. Check the weight comparison between a good set of alum's and steel's and you'll see they don't weigh that much less. Of course tune up is probably the biggest bearing killer in blown deals.

[cyclone]

do aluminum rods last as long as steel? right now i'm running lunati pro billet rods and crankshaft.

[Unchained]

do aluminum rods last as long as steel? right now i'm running lunati pro billet rods and crankshaft.
There's been a lot of debate on that too.
I ran a set of BME alumunum rods for four seasons on a lake boat, then took them out and sent them back to BME for inspection. They reported that they were still at original spec and could still be used.
I elected to buy a new set anyways.
Mine may have held up better because they were 7.25 long and had a real good rod length / stroke ratio. Also the engine wasn't really wrung out.
BME told me that what hurts them is overrevving.
I see the new Corvette engine uses Titanium rods.

[cyclone]

Michael Garret, just build an N/A motor and you wont have this problem. :D
Hopefully see you in Oct.
Ill be there with my blower, Chrissy.

[BUSBY]

I have used Brooks rods, Venolia, BME ... 97% come back when sent in as fine ... the 3% is from serious backfires, or other issues.
The aluminium used today in race rods is as good if not better than the steel IMO ... and Bill Miller's from what he told me.
There is a debate here though. Reciprocating motion & weight ... some builders thing RPMing now (0-8000 rpm ASAP) is attributed to lighter weights ... some truth to that ... others believe that more weight assists in HP gains which will overcome the need to RPM fast ... basically it depends on what you want to do w/ your engine.
For what you're going after ... you have great equipment. If you were going strictly race ... we'd be having a different conversation ... that blower and carbs would be out the window to start with! :wink:

[BUSBY]

Michael Garret
:D :D :D
funny

[MandDPerformance]

There is a debate here though. Reciprocating motion & weight ... some builders thing RPMing now (0-8000 rpm ASAP) is attributed to lighter weights ... some truth to that ... others believe that more weight assists in HP gains which will overcome the need to RPM fast ... basically it depends on what you want to do w/ your engine.
Brian,
Don't you meen that more weight can attribute to torque gains? Once again it all depends on the intended use of your engine.

[BUSBY]

Brian,
Don't you meen that more weight can attribute to torque gains? Once again it all depends on the intended use of your engine.
Yes ... thanks ... that is what I meant ... I don't agree with their ideology ... but maybe there is something to it.

[steelcomp]

I don't agree either. Recip weight might effect total hp if you're talking about the difference between a "cup" motor and a stock production type motor, but compared to a set of Brooks alum. vs. a set of Carillo's in the same motor, I doubt it's even measurable. It more effecte the rate of acclelration of the rotating assy, not the power. That's in the combustion chamber. I always hear the old saying about alum rods, " there's two kinds of alum rods. Those that have broken, and those that will." Most guys feel it's a matter of time, and pick a number of runs they'll go with their alum. rods, and then replace them. It's kinda what you think you can get away with. The problem with having them checked, is they can't detect metal fatuigue. That one rod might x-ray fine, and mag fine, and break the very next run. Ya just never know. They flex more than steel, which is why we like them, but they also work harden faster than steel. Just like bending a coat hanger. Bend it enough times, and it breaks. I know more guys run alum. becauase of the cushion effect, than because they're lighter. I'm building my blown alky motor with Brooks 65's and probably starting with a Mk. IV block, and a 4.25 crank/ 6.385" rod. I'm definately worried about cap walk and main bearings. Couldn't care less about rod bearings. Never had a problem with them.

[steelcomp]

There's been a lot of debate on that too.
I ran a set of BME alumunum rods for four seasons on a lake boat, then took them out and sent them back to BME for inspection. They reported that they were still at original spec and could still be used.
I elected to buy a new set anyways.
Mine may have held up better because they were 7.25 long and had a real good rod length / stroke ratio. Also the engine wasn't really wrung out.
BME told me that what hurts them is overrevving.
I see the new Corvette engine uses Titanium rods.
Actually your blown/turbo deal would much more favor a shorter ratio.

[Cs19]

I drove by Busby motorsports development tonight, didnt see anything going togethor.
Let me know when you guys assemble that fire breather, Ill come by and heckle you guys.
Chris.

[Unchained]

The problem with having them checked, is they can't detect metal fatuigue. That one rod might x-ray fine, and mag fine, and break the very next run. Ya just never know. They flex more than steel, which is why we like them, but they also work harden faster than steel. Just like bending a coat hanger. Bend it enough times, and it breaks. I know more guys run alum. becauase of the cushion effect, than because they're lighter.
BME told me that any sign of fatigue would show up as a change in the center to center dimension.
On the debate about aluminum rods I've alway had the question, how about the aluminum pistons ? They get way more heat, way more stress, the same reciprocations, and are a lot thinner than the rods yet they last for 100 k + miles in a car. I'm on the sixth season on the same pistons in my boat motor.

[steelcomp]

BME told me that any sign of fatigue would show up as a change in the center to center dimension.
On the debate about aluminum rods I've alway had the question, how about the aluminum pistons ? They get way more heat, way more stress, the same reciprocations, and are a lot thinner than the rods yet they last for 100 k + miles in a car. I'm on the sixth season on the same pistons in my boat motor.
Loads are completely different. Very little bending moment in pistons. It's the bending or flexing in the beam that kills rods. Also completely different alloys. Pistons contain all kinds of things like copper, silicone, nickle, etc. Very brittle in bending, but super strong in their application. A rod of the same alloy would brobably break right away. If you have a change in center to center the damage is already done. Fatigue can begin before changes in appearance or dimension.

[BUSBY]

I drove by Busby motorsports development tonight, didnt see anything going togethor.
Let me know when you guys assemble that fire breather, Ill come by and heckle you guys.
Chris.
We were debating if you would become a board member if we held the meetings at Mutt Lynch's ...

[BUSBY]

Mike ... make sure it's Coors Light Bottles ... 20 packs ... :D
Chris ... missed you tonight ... Mike, MikeF & I were BS'ing for at least 1.5 hours ...

[cyclone]

Mike ... make sure it's Coors Light Bottles ... 20 packs ... :D
Chris ... missed you tonight ... Mike, MikeF & I were BS'ing for at least 1.5 hours ...
you want them cheesy plastic bottles or the glass? :cool:

[BUSBY]

you want them cheesy plastic bottles or the glass? :cool:
Well ... neither until we've finished the critical parts ... :D
The by-standers can feel free to partake though ...
I was measuring things this morning ... you're lookin' good! :shift:

[cyclone]

Well ... neither until we've finished the critical parts ... :D
The by-standers can feel free to partake though ...
I was measuring things this morning ... you're lookin' good! :shift:
i knew you couldnt resist. :D

[BUSBY]

i knew you couldnt resist. :D
6am ... I had to get out there and dig around and see what we are playin with ... good stuff :D
This is gonna be fun!

[cyclone]

c'mon its just a mediocre river motor. nothin' special. :D

[BUSBY]

can I snap some pics of your bearings and see what others think?

[cyclone]

sure.