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.
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).]
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.
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.
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.
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).]
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).]
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.
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.
When you kill rod bearings in a turbo engine it's usually the tune, not the oil.
Have fun!
You are right Mender, and that was the first thing I checked on that K24 Nissan motor. I went through the timing table and it was a bit aggressive. After I re did the short block he was able to use a bit more aggression just to find out he lost power but at least with more cushion that gave him extra margins to be safe. I recommended to him not to push it because there's a point were too much is too much. He got better results retarding it some and leaning it out more, he picked up another 47whp.
Did you have gaskets between the spacer and block as well as the normal Fiero gasket for the valve cover? If so - what gasket?
Yes, cork gaskets for the sheet-metal valve covers. If you put the aluminum spacer directly on top of the iron head, the different thermal expansion rates can cause leaks. You need something soft between them, to act as a buffer.
Also, my 3.4 V6 came with studs instead of bolts for the valve covers. The studs have plenty of room for spacers.
[This message has been edited by Blacktree (edited 02-14-2018).]
If a person has to rely on other's mistakes to learn then that person has no sense of exploring or curiosity, he is just a parasite waiting to feed on other's misfortunes. That is sad!
I'm not saying you are a parasite Mender, I'm just responding to the author of what you posted.
Some more progress! Picked up my coated pistons today! A thermal coating on top and a super slick coating on the skirts. I have to weight match all of them now. The rods are already matched so are the lighter wrist pins. Next, one of each of these components are going to the machine shop along with a set of piston rings to be weighted to balance the crank taking into account the 2lbs weight savings on the rods and pistons. The crank is also getting knife edged.
Originally posted by La fiera: 3XX Supernatural rod
If you don't mind benefiting from the experience of others, I'd advise you to change the orientation of the grinding 90 degrees so that you aren't generating stress risers in a vulnerable plane. Also, a smoother surface finish would be a good idea.
A belt sander with a 120 grit belt does a very nice job of that.
[This message has been edited by mender (edited 02-19-2018).]
I agree with Mender. Those grinding marks are parallel with the wrist pin hole. That will encourage cracks in the end of the rod. You want the grinding marks to be perpendicular to that. Here's an example of what I'm talking about:
If you don't mind benefiting from the experience of others, I'd advise you to change the orientation of the grinding 90 degrees so that you aren't generating stress risers in a vulnerable plane. Also, a smoother surface finish would be a good idea.
A belt sander with a 120 grti belt does a very nice job of that.
I don't mind at all Mender! As a matter of fact some advises from Will, Blacktree, Lou Dias, Fieroguru and yourself to mention a few have made me revised certain things on this project. I think that by the time I finish this project it will not only be mine, It'll be ours! Your suggestion is very good but this picture was the rough cut only, they all will be polished and cryo treated along with the crank.
Some progress!! Now to the balancing act. The top 4 pistons are exactly match @ 435g each. The lower 2 are a bit higher so I'm working my way down. You can see the amount of metal taken out from all six so far. The wrist pins are much easier to balance, the first 2 are @ 107g the other 4 are @ 106g. They'll be easy to match.
Stock piston= 488g SN piston= 435g Stock wrist pin= 142g SN wrist pin= 106g
[This message has been edited by La fiera (edited 03-17-2018).]
The lower two are quite a bit heavier at 444 and 446 grams, so 9 and 11 grams over respectively.
I'm a little surprised at that discrepancy, most piston sets I get are not more than a couple grams either way. I match heavy pins to light pistons to reduce the amount of adjusting needed. Where are you taking material from for balancing the pistons?
with all the weight you have shaved off the pistons and rods I think you will need to have the crank balanced or you might end up with a bad vibration good luck it is a cool build
The lower two are quite a bit heavier at 444 and 446 grams, so 9 and 11 grams over respectively.
I'm a little surprised at that discrepancy, most piston sets I get are not more than a couple grams either way. I match heavy pins to light pistons to reduce the amount of adjusting needed. Where are you taking material from for balancing the pistons?
The problem was that these pistons come in set of 4 and I bought 2 separately. The package of 4 were within a gram or two but the other 2 are off by a lot, 11g like you mentioned. But I'm getting there little by little. To answer your question I drill little holes at low depth under the crown. I do it a little at a time and what I do in one side I repeat at the opposite side.
To answer Engine Man, The next step is to get the crank knife edged and balanced based on the weight taken off the rods and pistons and then the Pistons and rods will get Cryo threated.
Other advantage of these pistons is that they use a more robust set of ring thickness. Stock rings Top= 1.20mm Second= 1.50mm Oil= 3.00mm
SN rings Top= 2.0mm Second= 2.0mm Oil= 4.76mm
[This message has been edited by La fiera (edited 03-17-2018).]
I'm a visual person and like the saying "A picture can say a thousand words" this is how much weight I saved on the pistons and rods combined and not counting the crank shaft after it gets knife-edged and balanced.
I use stock torque after the ARP's are stretched but I always resize the con rod and block mains.
