300WHP Supernatural 3.XX Coming Soon! (Page 5/54)
La fiera JAN 28, 10:42 AM

quote
Originally posted by Will:

If you're pulling those bolts to greater than stock torque, it's a good idea to have the rods resized.



Yes Will and thank you for the reminder! I use stock torque after the ARP's are stretched but I always resize the con rod and block mains.
I like the clearances on the looser side and then make up with oil viscosity. That way I can take advantage of the shock absorber and cooling capability of the thicker oil.
mender JAN 28, 10:27 PM
I hope you mean that you use the recommended ARP torque, not the stock torque. Better yet would be to use the recommended stretch but not many people have a rod bolt stretch gauge and I've found the torque numbers supplied to be pretty close if the directions are followed (torque three times with ARP lube).

Going looser on the bearing clearance reduces the load carrying capability of the bearing. A good rule of thumb is to take the journal size and move the decimal point over. Eg, a 2.200 journal should be about 0.0022" for best balance of load vs cooling. Adjust your viscosity to get about 8.5 - 10 psi per 1000 rpm with hot oil.

[This message has been edited by mender (edited 01-28-2018).]

wftb JAN 28, 10:55 PM
The two engines I have built with ARP bolts I followed the ARP instructions and have had no problems. I thought the torque values were way to low in both cases but I remembered a thread where someone ignored the ARP figures and ended up with a seized engine. I have nothing but good things to say about ARP products.
La fiera JAN 29, 09:29 AM

quote
Originally posted by mender:

I hope you mean that you use the recommended ARP torque, not the stock torque. Better yet would be to use the recommended stretch but not many people have a rod bolt stretch gauge and I've found the torque numbers supplied to be pretty close if the directions are followed (torque three times with ARP lube).

Going looser on the bearing clearance reduces the load carrying capability of the bearing. A good rule of thumb is to take the journal size and move the decimal point over. Eg, a 2.200 journal should be about 0.0022" for best balance of load vs cooling. Adjust your viscosity to get about 8.5 - 10 psi per 1000 rpm with hot oil.




Yes, the ARP recommended torque for the application. As far as the oil pressure I've always ran on the looser side and I've never had an oil pressure problem.
I run a high volume oil pump and an oil cooler whenever I can even though the HV pump taxes the engine hp.
mender JAN 29, 11:12 AM
I build racing engines for a living and use the bearing clearances specified because they work best. These are engines that make 600+ hp in road race cars and rarely show wear when they get their yearly freshening.

Here's a site that has three graphs that you should look carefully at:
http://garage.grumpysperfor...ing-clearances.2726/

And some good stuff in this article:
http://www.hotrod.com/artic...nce-engine-bearings/
"On an engine prone to bearing failures, the old-school fix was a high-volume oil pump, thicker viscosity oil, looser bearing clearances, and maybe even fully-grooved main bearings. Current thinking considers these crutches counterproductive in most cases. They’re like a dog chasing its tail: It takes more power to spin a high-volume pump with thick, heavy oil, which is needed because of those big bearing clearances. But big clearances actually make it harder to establish and maintain the hydrodynamic oil film, as explained by Clevite’s technical literature: “Tighter clearances are desirable because they cause the curvature of the shaft and bearing to be more closely matched. This results in a broader oil film that spreads the load over more of the bearing surface, thus reducing the pressure within the oil film and on the bearing surface. This will in turn improve bearing life and performance.”

You're actually reducing the ability of the bearings to handle load by opening up the clearances, then adding extra pump volume and oil viscosity to compensate. Having done something the same way doesn't mean that it's the best way. As mentioned, I build a lot of engines and can see the results of any changes I make. I use the clearances that have proven to work the best.

As usual, your choice.

[This message has been edited by mender (edited 01-29-2018).]

pmbrunelle JAN 29, 12:23 PM

quote
Originally posted by mender:
You're actually reducing the ability of the bearings to handle load by opening up the clearances, then adding extra pump volume and oil viscosity to compensate. Having done something the same way doesn't mean that it's the best way. As mentioned, I build a lot of engines and can see the results of any changes I make. I use the clearances that have proven to work the best.



By reducing the clearances, you reduce the ability of the bearing to accomodate dimensional errors, or taper / out-of-round.

So, by running looser, La Fiera gets an insurance that the engine will run right despite less-than-perfect parts.

Nobody would do something "bad" if there wasn't a positive upside associated with it.

[This message has been edited by pmbrunelle (edited 01-29-2018).]

Blacktree JAN 29, 02:12 PM
Rei and I have talked about it on the phone a couple times. I'm pretty sure he understands the 'new school' way of building an engine, but prefers to use the 'old school' method. That's his prerogative, and I respect that.

That said, Rei clued me into the MoS2 additive. Apparently it's even better than ZDDP. So I want to try it out. My engine has tight bearing clearances and thin engine oil (5w20), so a good additive package is really important.
mender JAN 29, 07:43 PM

quote
Originally posted by pmbrunelle:


By reducing the clearances, you reduce the ability of the bearing to accomodate dimensional errors, or taper / out-of-round.

So, by running looser, La Fiera gets an insurance that the engine will run right despite less-than-perfect parts.

Nobody would do something "bad" if there wasn't a positive upside associated with it.



If your machining is sloppy enough to require extra room for errors, go to a different machine shop.

I wish I had your faith in human nature; lots of people do "bad" things for the wrong reasons even when they know better.
Will JAN 29, 08:28 PM

quote
Originally posted by mender:

If your machining is sloppy enough to require extra room for errors, go to a different machine shop.



Ditto... to run right, it's gotta be done right.


quote
Originally posted by mender:
I wish I had your faith in human nature; lots of people do "bad" things for the wrong reasons even when they know better.



Like laziness, lack of funds, ignorance... yeah.
La fiera JAN 29, 08:59 PM

quote
Originally posted by pmbrunelle:


By reducing the clearances, you reduce the ability of the bearing to accomodate dimensional errors, or taper / out-of-round.

So, by running looser, La Fiera gets an insurance that the engine will run right despite less-than-perfect parts.

Nobody would do something "bad" if there wasn't a positive upside associated with it.




I also build engines for a living on my spare time and that's exactly why I choose to use the looser clearances. 99% of the time customers send me their own parts and if something goes bad because one of their parts was out of tolerance (which I end up correcting it anyways) and something goes wrong they are not going to blame the part.

I remember like 5 years ago a customer with a K24 Nissan turbo built his own engine twice and twice he killed the rod bearings and he had the best parts you can get for that motor, Steel racing crank, Oliver rods, forged pistons, piston cooling squirters and all the good things. He followed the Nissan workshop manual and used 10W-30 oil.
I re-did the short block with the looser clearances and recommended 10W-60 and is all good now. It makes 674WHP and he drag races almost every weekend and drives it almost all year (here the winters are short).
All I told him was to just make sure the engine is up to temperature before pounding it and the car still runs strong. I should be getting it soon for a refresh.

I don't follow that "Monkey see monkey do" trend, I use the approach that has worked for me through the years. The reason I have a 3.4 is because trying to get the last ounce of hp out my 2.8 I did the tight clearance and low viscosity oil and what happened? At a track event It shredded the stock harmonic balancer at 6800rpm and it was vibrating so violently that I thought the crankshaft broke. Drove it to the pits crawling and shot the engine off but the damage was already done. Installed a new balancer and it had a loud rod knock, rod bearing #3 hammered and all the others but not as bad. What did I learned from this? Leave some margin for error like PMbrunnell said.

Unless I get parts that are F1 quality I will always use looser clearances because the metallurgy of today is crap regardless if is American or Chinese.

So yes, Hot Rod magazine and Clevite experts can recommend an intelligent approach to get the most out of an engine but my experience has showed me that in certain situations the "intelligent" choice isn't always the smart one.