[feuer]

Originally Posted by mweisdorfer

I was thinking about this one


Brown Line Metalworks BLDAG001 Digital Angle Gauge https://www.amazon.com/dp/B00CP8E61E..._kLDbFb4EMSBSZ

Or maybe just getting another torque wrench all together that reads angles like this one below


Flex Head Electronic Torque Wrench with Angle https://www.amazon.com/dp/B07TFHW17F..._KMDbFbE2G4HNE

The BLDG001 is interesting. Can be attached to different size wrenches. Thank you for sharing.

[feuer]

More and more Saif2018 https://www.e90post.com/forums/showt...3#post26412033

[mweisdorfer]

Originally Posted by B6T

Not sure why you'd want to go with ARP bolts... I'd imagine that they really only have a place in a higher-revving engine where you're subjecting the bolts to higher levels of tension from higher engine speeds (i.e. S65, S85).

With a relatively low revving engine like the N54, where the engine's power comes from turbocharging, and comparatively the forces on the rod are more compressive, the stock bolts are likely more than suitable.

IMO, the rod bolts in an N54 shouldn't see any difference in stress level whether the engine is stock or 500hp, as long as the rev limit is maintained in both scenarios.

Ok. So, I've been taking with the guy who made the video I posted here. The video was of a guy using ARP bolts on the rod bearings of an N54.

He said his car is perfectly fine (almost 2 years later) and it makes 507 HP.

He also said the rods are forged, so how does 36 foot pounds of torque distort the rods?

He makes a valid point...

I know a the guys at the BMW dealership near me in the service dept. I might drop by and ask them their opinion.

[feuer]

Originally Posted by mweisdorfer

I know a the guys at the BMW dealership near me in the service dept. I might drop by and ask them their opinion.

Honestly I highly doubt that they will know unless they do engine builds on the side since at the dealer they only use bmw parts. Probably is better to talk to actual engine builders instead.

[Foghorn]

Which ARP bolts are being used? I only see a kit for the S65 (201-6001), no listing for the N54, though the bolts are the similar spec.

36# doesn’t sound nearly tight enough for connecting rod bolts.

For the S65, ARP recommends;

ARP recommends using the STRETCH METHOD when tightening rod bolts. Following the instructions for using a stretch gauge, Stretch the bolts to . 0075 - . 0080 .
If you do not have a stretch gauge, torque the bolts to _ 60 ft-lbs using ARP Ultra-Torque Fastener Assembly Lubricant.

Update: I see the ARP 201-6303 bolts are the ones used. Indeed ARP recommends 36# for these bolts, I find this on the light side but here is the procedure;

ARP recommends using the STRETCH METHOD when tightening rod bolts. Following the instructions for using a stretch gauge, Stretch the bolts to . 0070 - . 0075 .
If you do not have a stretch gauge, torque the bolts to _ 36 ft-lbs using ARP Ultra-Torque Fastener Assembly Lubricant.

I’ll stick to the BMW bolts and torque spec.

[mweisdorfer]

Originally Posted by Foghorn

Which ARP bolts are being used? I only see a kit for the S65 (201-6001), no listing for the N54, though the bolts are the similar spec.

36# doesn’t sound nearly tight enough for connecting rod bolts.

For the S65, ARP recommends;

ARP recommends using the STRETCH METHOD when tightening rod bolts. Following the instructions for using a stretch gauge, Stretch the bolts to . 0075 - . 0080 .
If you do not have a stretch gauge, torque the bolts to _ 60 ft-lbs using ARP Ultra-Torque Fastener Assembly Lubricant.

Update: I see the ARP 201-6303 bolts are the ones used. Indeed ARP recommends 36# for these bolts, I find this on the light side but here is the procedure;

ARP recommends using the STRETCH METHOD when tightening rod bolts. Following the instructions for using a stretch gauge, Stretch the bolts to . 0070 - . 0075 .
If you do not have a stretch gauge, torque the bolts to _ 36 ft-lbs using ARP Ultra-Torque Fastener Assembly Lubricant.

I’ll stick to the BMW bolts and torque spec.

Originally Posted by Foghorn

Which ARP bolts are being used? I only see a kit for the S65 (201-6001), no listing for the N54, though the bolts are the similar spec.

36# doesn't sound nearly tight enough for connecting rod bolts.

For the S65, ARP recommends;

ARP recommends using the STRETCH METHOD when tightening rod bolts. Following the instructions for using a stretch gauge, Stretch the bolts to . 0075 - . 0080 .
If you do not have a stretch gauge, torque the bolts to _ 60 ft-lbs using ARP Ultra-Torque Fastener Assembly Lubricant.

Update: I see the ARP 201-6303 bolts are the ones used. Indeed ARP recommends 36# for these bolts, I find this on the light side but here is the procedure;

ARP recommends using the STRETCH METHOD when tightening rod bolts. Following the instructions for using a stretch gauge, Stretch the bolts to . 0070 - . 0075 .
If you do not have a stretch gauge, torque the bolts to _ 36 ft-lbs using ARP Ultra-Torque Fastener Assembly Lubricant.

I'll stick to the BMW bolts and torque spec.

ARP bolts are using the threads to tighten. Regular bolts are using the head only to tighten. Hence, why only 36# vs 50# & two 70 Degree turns

[Foghorn]

Originally Posted by mweisdorfer

ARP bolts are using the threads to tighten. Regular bolts are using the head only to tighten. Hence, why only 36# vs 50# & two 70 Degree turns

Stretch is the optimal method to determine load on a bolt. Kind of hard to measure stretch on a blind bolt so instead the torque value is substituted, with or without using angle of rotation values. Ideally three steps are used to correctly tighten the bolts, an initial value to seat the parts together then a clamp value followed by the final torque or rotation value. Degrees rotation is a better reference than torque to achieve the desired stretch.

In any case, ARP claims 36# torque using the recommended lubricant on the 201-6303 bolts is sufficient to obtain 0.070” to 0.075” stretch. No doubt ARP is confident from testing this application, they definitely have a good reputation and I’ve used their products in other applications.

I’m just surprised 36# provides enough stretch, especially when you compare the S65 bolts to the N54 bolts.

[mweisdorfer]

Originally Posted by Foghorn

Stretch is the optimal method to determine load on a bolt. Kind of hard to measure stretch on a blind bolt so instead the torque value is substituted, with or without using angle of rotation values. Ideally three steps are used to correctly tighten the bolts, an initial value to seat the parts together then a clamp value followed by the final torque or rotation value. Degrees rotation is a better reference than torque to achieve the desired stretch.

In any case, ARP claims 36# torque using the recommended lubricant on the 201-6303 bolts is sufficient to obtain 0.070" to 0.075" stretch. No doubt ARP is confident from testing this application, they definitely have a good reputation and I've used their products in other applications.

I'm just surprised 36# provides enough stretch, especially when you compare the S65 bolts to the N54 bolts.

In the video I posted, that's what he did, 10# then 20# then 36#.

The M3 guys use a modified version of ARP bolts made by BE.

[feuer]

Originally Posted by Foghorn

Stretch is the optimal method to determine load on a bolt. Kind of hard to measure stretch on a blind bolt so instead the torque value is substituted, with or without using angle of rotation values. Ideally three steps are used to correctly tighten the bolts, an initial value to seat the parts together then a clamp value followed by the final torque or rotation value. Degrees rotation is a better reference than torque to achieve the desired stretch.

In any case, ARP claims 36# torque using the recommended lubricant on the 201-6303 bolts is sufficient to obtain 0.070” to 0.075” stretch. No doubt ARP is confident from testing this application, they definitely have a good reputation and I’ve used their products in other applications.

I’m just surprised 36# provides enough stretch, especially when you compare the S65 bolts to the N54 bolts.

Is either three step or at least two step torque process, so 36 then 36 again and 36 again, or 36 then 50. Is definitely not just single 36

[B6T]

Originally Posted by mweisdorfer

Ok. So, I've been taking with the guy who made the video I posted here. The video was of a guy using ARP bolts on the rod bearings of an N54.

He said his car is perfectly fine (almost 2 years later) and it makes 507 HP.

He also said the rods are forged, so how does 36 foot pounds of torque distort the rods?

He makes a valid point...

I know a the guys at the BMW dealership near me in the service dept. I might drop by and ask them their opinion.

What is his valid point? That his car not blowing up after 2 years, making basic FBO power is a convincing argument for using ARP bolts instead of stockers?

The argument as I understand it is that the rods will distort because the ARP bolts subject the area along/around the threads and under the head of the fastener to a higher level of compressive force than the stock bolts do. Doesn't have anything to do with them being forged necessarily, but more to do with the fasteners being torqued to a higher level than when they were assembled for machining, thus resulting in a different (out-of-round) shape once assembled at the higher torque. Forged materials are still elastic.

I'm not sure what the resulting difference in tensile force in the bolt shank at 36 ft lbs with lubricated threads and the BMW spec is but if you figure that out we could plug it into an FEA analysis if you really wanted to see the difference.

[B6T]

Originally Posted by mweisdorfer

ARP bolts are using the threads to tighten. Regular bolts are using the head only to tighten. Hence, why only 36# vs 50# & two 70 Degree turns

Can you clarify what this means? ARP bolts use the threads to tighten, regular bolts only use the head to tighten? In either case, you turn the head to wind the bolt down. Tensile forces in the bolt shank resulting from application of torque compress the mating parts. How can it be different between the two bolts?

[mweisdorfer]

Originally Posted by B6T

Can you clarify what this means? ARP bolts use the threads to tighten, regular bolts only use the head to tighten? In either case, you turn the head to wind the bolt down. Tensile forces in the bolt shank resulting from application of torque compress the mating parts. How can it be different between the two bolts?

Go to about 1:00 min into this video. He does a good job of explaining how ARP bolts differ from regular bolts

[Rube]

Originally Posted by mweisdorfer

Go to about 1:00 min into this video. He does a good job of explaining how ARP bolts differ from regular bolts

He replaced the bolts with studs/nuts, that’s the difference. Some good info here

https://www.thomasnet.com/articles/h...ad-stud-bolts/

[B6T]

I did a compression test on my engine and found cylinders 1-4 around 160-170psi, but cylinder 5 at 95psi and cylinder 6 at 145psi.

I'm wondering if this drop in compression in #5 is due to the rod bearing? In other words, is it possible that the 'squished' bearing reduced the piston's distance from TDC significantly enough to drop the compression.

If not... bent rod?

[Rube]

Originally Posted by B6T

I did a compression test on my engine and found cylinders 1-4 around 160-170psi, but cylinder 5 at 95psi and cylinder 6 at 145psi.

I'm wondering if this drop in compression in #5 is due to the rod bearing? In other words, is it possible that the 'squished' bearing reduced the piston's distance from TDC significantly enough to drop the compression.

If not... bent rod?

a defective rod bearing shouldn't affect compression #s. That's more indicative of a head gasket issue, burned/bent valve, cracked piston, broken piston ring etc.

[mweisdorfer]

Originally Posted by B6T

Can you clarify what this means? ARP bolts use the threads to tighten, regular bolts only use the head to tighten? In either case, you turn the head to wind the bolt down. Tensile forces in the bolt shank resulting from application of torque compress the mating parts. How can it be different between the two bolts?

" I'm not sure what the resulting difference in tensile force in the bolt shank at 36 ft lbs with lubricated threads and the BMW spec is but if you figure that out we could plug it into an FEA analysis if you really wanted to see the difference. "

It would be interesting to see that comparison. Tensile strength of ARP bolts torqued at 36# with their special lubricant on the threads vs BMW rod bearing bolts torqued at 14.75# (20nm) plus two 70 degree turns & motor oil on the threads...

[feuer]

Originally Posted by B6T

I did a compression test on my engine and found cylinders 1-4 around 160-170psi, but cylinder 5 at 95psi and cylinder 6 at 145psi.

I'm wondering if this drop in compression in #5 is due to the rod bearing? In other words, is it possible that the 'squished' bearing reduced the piston's distance from TDC significantly enough to drop the compression.

If not... bent rod?

Cyl 5 is the hottest. Experiencing most knock. Which probably took you bearing and the piston rings

[B6T]

Originally Posted by feuer

Cyl 5 is the hottest. Experiencing most knock. Which probably took you bearing and the piston rings

I got the engine on a stand tonight and tore the oil pan off.

#5 was the spun bearing. All others look intact... but not perfect.

Interestingly enough, with the engine upside down, the #4, 5, and 6 bores are filled with oil. You can't see the small end of the rod in these pistons, since they are submerged in the pool of oil. I guess this a result of how I had the engine positioned before putting it on the stand.

I'm going to look for oil dripping out of the spark plug tube on #5 tomorrow. If there is oil dripping out, it means that it got past the rings, which could mean that the rings are bad. But if the oil is all still there... wouldn't it indicate the rings are still good?