Ebay crank girdles

[digger]

i'm a mechanical engineer and have worked doing structural design and analysis for a decade and a half. the girdle looks like it offers not that much additional stiffness in most directions
- the cutouts are too big such that the stiffness comes from the bending of the rectangular sections.
- the section properties of parts that are reduced to offering bending resistance (by virtue of the large cutouts) are not that great
- the caps dont get tied back to the sides of the block

better than nothing....but not that great

[DunDunSkeert]

http://www.suprastore.com/su2jzengikit.html Guys have been using girdle similar to the ebay one in 2JZs for quite some time. Going to do some research on their experiences and report back.

[digger]

atleast the supra one is starting to get to a decent thickness (looks almost a thick as the bolt diameter) and they have not cut a big hole between the bolt pairs

[TheJuggernaut]

Can anyone provide any practical proof that these engines need this? (ie not based on feelings or appeals to authority about what's been done on other engines)

[wazzu70]

Can anyone provide any practical proof that these engines need this? (ie not based on feelings or appeals to authority about what's been done on other engines)

I havent seen a lot of evidence as in destroyed main bearings, ect. I think it starts becoming more of a problem with extended times at higher rpm. An improved TV damper should help keep the crank bending down. Not sure at what point you would need both.

A street car with a mild power output (500whp) shouldn't even be considering this IMO. TBD at what point block rigidity becomes a concern.

[jakermac]

The IE one (https://www.performancebyie.com/blog...-installation/) ties to the pan flange. All that would really need to happen is to dowel all the main bolt holes and then line bore the mains and you'd have the full benefit. I think any time you make things more rigid you gain a benefit (to a certain extent) as any flexing/movement would ultimately lead to increased internal friction.

[Def]

i'm a mechanical engineer and have worked doing structural design and analysis for a decade and a half. the girdle looks like it offers not that much additional stiffness in most directions
- the cutouts are too big such that the stiffness comes from the bending of the rectangular sections.
- the section properties of parts that are reduced to offering bending resistance (by virtue of the large cutouts) are not that great
- the caps dont get tied back to the sides of the block

better than nothing....but not that great

So going from "it does nothing" to "does something, but not great." The later of which is what I've been saying the whole time.

You backpedaled to my position nicely.

[Def]

I havent seen a lot of evidence as in destroyed main bearings, ect. I think it starts becoming more of a problem with extended times at higher rpm. An improved TV damper should help keep the crank bending down. Not sure at what point you would need both.

A street car with a mild power output (500whp) shouldn't even be considering this IMO. TBD at what point block rigidity becomes a concern.

A TV damper on the crankshaft can reduce bending in the crankshaft, but if your main caps and block itself is twisting, then you're going to wear the bearings. It's not a matter of a girdle eliminating ALL block flex, you just want to keep it well within your main clearance.

Each item does a different thing, which is why many high performance engines have both items.

[milKt]

aMORica

just install the mod and know ... that you're adding the best failsafes to a timebomb.

Better safe than sorry.

¢utting ring
ARP main$
$uperte¢h valvetrain
ATI damper$
210mm diff$
¢ryo axle$/$tub$
DSS drive $haft
BB throttle body
$pecial ¢oating$
4" intake
5-6" thi¢k inter¢ooler

All play a part in "better"

[someguy2800]

Have you ever observed the stiffness of a crank or block? When I was in school I spent some time messing around with a crank straightening machine. It was a very rigid cast iron fixture with adjustable V blocks to put a crank in and a dial indicator to measure the run out. The actual straightening was done with a small hand pump hydraulic ram with a pressure gauge on it. It took surprisingly little force to bend a crank past its elastic limit to straighten it. You could bend a crank by a few thousands of an inch just by pushing on the center of a crank with your hands, though of course it took considerable more force than that to reach the elastic limit. We also used the same fixture to straighten cylinder heads which took a considerable amount of force to do, and I remember someone straightening an aluminum 4 cylinder block with it by heating it up to about 400 degrees and putting it in there. One of the other things I noticed was when I did some autopsies on a couple small block chevy's I rebuilt I noticed that the main bearings were out of alignment and the crankshafts were bent by a few thousands of an inch, yet the main bearings that came out of the motor were in okay condition. I'll bet the cranks were crooked from the factory and blocks had taken a settle with age as there internal stresses relieved.

Anyway those experiences brought me to the conclusion that it is not the stiffness of the crankshaft or a block that keeps the bearings alive in a motor but rather the film strength of the oil. The crank and block are both free to flex and bow together as force is applied and released to different areas of the crank and block but the film strength of the oil keeps the crank floating within the bore of the bearings. The stiffness of the two parts is not enough to keep them in alignment. If the block is really flimsy the two can deflect to the point of exceeding the elastic limit of the crank and bending in it permanently or repeatedly bending it and fatiguing it to the breaking point such as what often happens on older flimsy oem v8's when pushed to there limit. If the block is stiff enough it will just pull the main cap away from the block and you will see signs of cap walk and the caps will loose tension in there registers from flexing in the center and pinching on the crank. Some motors will rip the main web right out of the block leaving a broken chunk of casting left bolted to the main cap. If the block and caps and cap bolts are all strong enough to stay in place and you apply enough force to the crank it will either exceed the film strength of the oil or the compressive strength of the bearing shell, then you start wiping the bearing material or pounding the bearings shell out of round. I just don't personally see how a bolt on stud girdle achieves the goal of allowing the block and crank to flex with each other and keep the main caps round and firmly loaded in the Z axis into there registers.

[Butters Stoch]

This guy ^^^ is making 800 something on stock rods and pistons, Frank is doing the same, myself and a handful others are in the 700whp range, and a large amount are in the 500-650 range, all without fancy girdles, aged head studs, and fine wine. We rely on hookers and blow. None of this crazy stuff.
Next we will be discussing $400 catch cans and why we need them ? We should be doing R&D on paddle shifting DCT's for our cars. Now that would be worth a few thousand dollars.

[milKt]

We should be doing R&D on paddle shifting DCT's for our cars. Now that would be worth a few thousand dollars.

More.

[someguy2800]

This reminds me of when I first got out of school and was going around talking to a few domestic engine builders about getting a job. At the time there were just a few people making over 600 or so and telling about it. I set a goal for myself of 800 at the tire and while talking to some of the engine shops I was going around to while looking for a job they were all dumbfounded by that goal from 2.8 liters. In there heads they were equating it to what they have to do to make a SBC hold X amount of power per liter and they are all telling me I need 1/2" head studs and a copper head gasket with orings and receiver grooves, a billet crank, billet main caps with splayed bolts, inconel valves with beryllium valve seats, 300+ duration cams, a dry sump oil system and I'll need to dry fill the block and run it on methanol and it will need an 80mm turbo and never spool and only make power at 10,000 rpms. After that I wasn't all that interested in working for any of those guys. Looking back on it I think there is only a couple of them that are still in business.

[328iFun]

I often tell people at work what I've been doing to my car and the power it can eventually make. Most guys I work with are ^ chevy/ford mustang guys that often 'humor' me when I explain my car to them.

I guess unless its an SBC or or has less than 8 cylinders high output isn't possible. I had an engine diagram of the m70 as my desktop background at work and I actually had someone come in and talk about how an earlier SBC was/or is a better motor.

I guess if you don't spend 20-30k on car, it isn't quick.

I've owned and driven many camaros with the SBC whether its 305/350 carb or FI. I can say personally, all of them were straight up dogs and V6 Grandam HO would walk on them. I've also driven several mustangs whether there 6's or V8's, still slow. Basically putting a truck motor in a car. I bet I could've pulled a boat with either one of my camaros though

[TheJuggernaut]

I was talking dog boxes with a Trans Am shop and upon finding out I make more power out of a 3.2 than their big V8s he concentrated his effort on explaining to me that a 200rpm power band is good for bragging on the internet but useless for road racing. Until I sent him my dyno showing a wider powerband than his cars, he verbally tipped his hat and got back to talking gear ratios

This reminds me of when I first got out of school and was going around talking to a few domestic engine builders about getting a job. At the time there were just a few people making over 600 or so and telling about it. I set a goal for myself of 800 at the tire and while talking to some of the engine shops I was going around to while looking for a job they were all dumbfounded by that goal from 2.8 liters. In there heads they were equating it to what they have to do to make a SBC hold X amount of power per liter and they are all telling me I need 1/2" head studs and a copper head gasket with orings and receiver grooves, a billet crank, billet main caps with splayed bolts, inconel valves with beryllium valve seats, 300+ duration cams, a dry sump oil system and I'll need to dry fill the block and run it on methanol and it will need an 80mm turbo and never spool and only make power at 10,000 rpms. After that I wasn't all that interested in working for any of those guys. Looking back on it I think there is only a couple of them that are still in business.

[digger]

So going from "it does nothing" to "does something, but not great." The later of which is what I've been saying the whole time.

You backpedaled to my position nicely.

Of course Everything does something, without even changing the concept of the eBay part you could make it quite a bit more effictive. Then you can change the concept to be even better like the ie bits. The closer you get to what BMW does on newer engines the better and the eBay part is along way away. What specific issue are people trying to solve ? Is there evidence of a problem ?

[Def]

Have you ever observed the stiffness of a crank or block? When I was in school I spent some time messing around with a crank straightening machine. It was a very rigid cast iron fixture with adjustable V blocks to put a crank in and a dial indicator to measure the run out. The actual straightening was done with a small hand pump hydraulic ram with a pressure gauge on it. It took surprisingly little force to bend a crank past its elastic limit to straighten it. You could bend a crank by a few thousands of an inch just by pushing on the center of a crank with your hands, though of course it took considerable more force than that to reach the elastic limit. We also used the same fixture to straighten cylinder heads which took a considerable amount of force to do, and I remember someone straightening an aluminum 4 cylinder block with it by heating it up to about 400 degrees and putting it in there. One of the other things I noticed was when I did some autopsies on a couple small block chevy's I rebuilt I noticed that the main bearings were out of alignment and the crankshafts were bent by a few thousands of an inch, yet the main bearings that came out of the motor were in okay condition. I'll bet the cranks were crooked from the factory and blocks had taken a settle with age as there internal stresses relieved.

Anyway those experiences brought me to the conclusion that it is not the stiffness of the crankshaft or a block that keeps the bearings alive in a motor but rather the film strength of the oil. The crank and block are both free to flex and bow together as force is applied and released to different areas of the crank and block but the film strength of the oil keeps the crank floating within the bore of the bearings. The stiffness of the two parts is not enough to keep them in alignment. If the block is really flimsy the two can deflect to the point of exceeding the elastic limit of the crank and bending in it permanently or repeatedly bending it and fatiguing it to the breaking point such as what often happens on older flimsy oem v8's when pushed to there limit. If the block is stiff enough it will just pull the main cap away from the block and you will see signs of cap walk and the caps will loose tension in there registers from flexing in the center and pinching on the crank. Some motors will rip the main web right out of the block leaving a broken chunk of casting left bolted to the main cap. If the block and caps and cap bolts are all strong enough to stay in place and you apply enough force to the crank it will either exceed the film strength of the oil or the compressive strength of the bearing shell, then you start wiping the bearing material or pounding the bearings shell out of round. I just don't personally see how a bolt on stud girdle achieves the goal of allowing the block and crank to flex with each other and keep the main caps round and firmly loaded in the Z axis into there registers.

Yes, I've seen how stiff castings of similar sizes to an engine block are, and even larger items. It's fairly easy to calculate a rough order of magnitude of stiffness - math, it works.

Calculate what the BMEP of a ~100-150 rwhp/cylinder M50 based engine is, it's high, but not insane. Now calculate out the forces of the piston and rod spinning at 7000 RPM - high as well.


I'll say it again, I'm not saying every turbo/SC M5x build needs a girdle, but to say it's not going to help hold the engine together better is stupid. By inspection it will make the main caps stiffer and held in place better. It's up for the individual to see if they think it's worth it.

I agree that the IE girdle that ties to the oil pan mounting surface of the block is a better solution while costing a bit more $$$.

[TheJuggernaut]

I'll say it again, I'm not saying every turbo/SC M5x build needs a girdle, but to say it's not going to help hold the engine together better is stupid. By inspection it will make the main caps stiffer and held in place better. It's up for the individual to see if they think it's worth it.

Stupid, really? That's how you make your engineering decisions, throw things in because it might do some good? That sounds pretty stupid to me, like walking around the house setting off a fire extinguisher because it can't hurt if there's a fire around. Without data to demonstrate a problem, you are not fixing or helping anything. You're tilting at windmills.

[Def]

Stupid, really? That's how you make your engineering decisions, throw things in because it might do some good? That sounds pretty stupid to me, like walking around the house setting off a fire extinguisher because it can't hurt if there's a fire around. Without data to demonstrate a problem, you are not fixing or helping anything. You're tilting at windmills.

You guys are way too far up the internet forum groupthink butthole and you're not even thinking about this in a logical way.

Let me break it down for you:

1. I'm not making any claims on if you need this to keep your beat up, used engine holding together.

2. No engine EVER performs better by having the main bore move around due to the forces being imparted to it via combustion pressure and inertial loads.

3. If you accept number 2, you can accept that any engine will typically withstand higher power with a stiffer bottom end that keeps the main bore concentric and in plane.

4. Adding a crank girdle or split bedplate design is the accepted solution to do number 2.




Again, if you need it for your application - your call. But you're STUPID if you cannot accept that engines want to keep their main bore well positioned.

[TheJuggernaut]

Can anyone provide any practical proof that these engines need this? (ie not based on feelings or appeals to authority about what's been done on other engines)

Not me.

Got it.

[Def]

Got it.

Like I've said quite a few times... up to the individual user to determine if it's worth it for their build.


This reminds me of the years of you doofuses yelling beautifully informed things like, "really small cams make the most power with a turbo" and "DME tunes are way better than a standalone!!!"

[someguy2800]

I for one am just glad your here to teach us dum dums how its done.

[bry195]

Remember when kro cop got kro copped? I felt bad.
ironicly I wanted to bathe in the blood of the one we call DEF and now that I have ....lolol.. other than a few giggles im going to take the high road so DEF doesnt focus that sputnik size brain on us dreamers. i never thought I'd see DEF take on an open minded perspective but shite I was happy to see it. You must be getting worn down DEF but I'm with ya. I know F---all about girdle applications but your point is understood. Whether you are right or wrong I just feel better knowing that darth vader might have a heart somehwere in there.....maybe.

[DunDunSkeert]

Have you ever observed the stiffness of a crank or block? When I was in school I spent some time messing around with a crank straightening machine. It was a very rigid cast iron fixture with adjustable V blocks to put a crank in and a dial indicator to measure the run out. The actual straightening was done with a small hand pump hydraulic ram with a pressure gauge on it. It took surprisingly little force to bend a crank past its elastic limit to straighten it. You could bend a crank by a few thousands of an inch just by pushing on the center of a crank with your hands, though of course it took considerable more force than that to reach the elastic limit. We also used the same fixture to straighten cylinder heads which took a considerable amount of force to do, and I remember someone straightening an aluminum 4 cylinder block with it by heating it up to about 400 degrees and putting it in there. One of the other things I noticed was when I did some autopsies on a couple small block chevy's I rebuilt I noticed that the main bearings were out of alignment and the crankshafts were bent by a few thousands of an inch, yet the main bearings that came out of the motor were in okay condition. I'll bet the cranks were crooked from the factory and blocks had taken a settle with age as there internal stresses relieved.

Anyway those experiences brought me to the conclusion that it is not the stiffness of the crankshaft or a block that keeps the bearings alive in a motor but rather the film strength of the oil. The crank and block are both free to flex and bow together as force is applied and released to different areas of the crank and block but the film strength of the oil keeps the crank floating within the bore of the bearings. The stiffness of the two parts is not enough to keep them in alignment. If the block is really flimsy the two can deflect to the point of exceeding the elastic limit of the crank and bending in it permanently or repeatedly bending it and fatiguing it to the breaking point such as what often happens on older flimsy oem v8's when pushed to there limit. If the block is stiff enough it will just pull the main cap away from the block and you will see signs of cap walk and the caps will loose tension in there registers from flexing in the center and pinching on the crank. Some motors will rip the main web right out of the block leaving a broken chunk of casting left bolted to the main cap. If the block and caps and cap bolts are all strong enough to stay in place and you apply enough force to the crank it will either exceed the film strength of the oil or the compressive strength of the bearing shell, then you start wiping the bearing material or pounding the bearings shell out of round. I just don't personally see how a bolt on stud girdle achieves the goal of allowing the block and crank to flex with each other and keep the main caps round and firmly loaded in the Z axis into there registers.

Are you saying it's a bad thing that I crashed my car into my crank that was sitting on my couch when it was out of my motor?

[dcvee]

No wonder your wife doesn't argue with you....she's probably tired of getting shit through your thick skull. I know I am...too many years of you
being an asshole.
Don

Like I've said quite a few times... up to the individual user to determine if it's worth it for their build.


This reminds me of the years of you doofuses yelling beautifully informed things like, "really small cams make the most power with a turbo" and "DME tunes are way better than a standalone!!!"

- - - Updated - - -

No shit...that was the joke. No wonder you call yourself "DEF".

Don

Shows what you know, the girdle for one crankcase is.... THE OTHER CRANKCASE!