Rod choice for hi-po/low rev setup?
10-18-2002, 07:24 AM
#17
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Taylormade - Please describe what the F2/F4/F6 etc skirts are. I haven't seen that description before. Thanks!
The wrist pins I'm going with for the Z28tt (400 cid, 3.750 stroke, 4.1215 bore, 20 psi) are the JE 52 series tool steel .927 dia x 2.950 length x .180 wall thickness. We were concerned about wristpin flex & distortion in the pin bore. Since I'm running a hydraulic roller, I won't be spinning the rpms, so light weight isn't as critical (162 grams!). We're having the wristpins Casidian coated as well (at Anatech). It's a diamond-like carbon coating that increases lubricity between piston/pin contact, and should prevent a failure. It was highly suggested by my cup engine builder friends.
Andris
The wrist pins I'm going with for the Z28tt (400 cid, 3.750 stroke, 4.1215 bore, 20 psi) are the JE 52 series tool steel .927 dia x 2.950 length x .180 wall thickness. We were concerned about wristpin flex & distortion in the pin bore. Since I'm running a hydraulic roller, I won't be spinning the rpms, so light weight isn't as critical (162 grams!). We're having the wristpins Casidian coated as well (at Anatech). It's a diamond-like carbon coating that increases lubricity between piston/pin contact, and should prevent a failure. It was highly suggested by my cup engine builder friends.
Andris
10-18-2002, 08:19 AM
#18
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Shirts on pistons appear to be round but they are not(at least on a quality racing piston). They have an eliptical shape built into them. The difference in the shirts are the shapes and tapers. You'd probably need to talk to JE or CP as I can't tell you the exact differences the specs on the different shirts but their is alot more than the ones I described.
I usually use a 2.500 length pin even in a 4.125 bore to help pin wieght but this requires custom pistons or someone to remachine the spiral lock groove or use a pressed fit rod.
I usually use a 2.500 length pin even in a 4.125 bore to help pin wieght but this requires custom pistons or someone to remachine the spiral lock groove or use a pressed fit rod.
Last edited by TAYLORMADE; 10-18-2002 at 08:22 AM.
10-18-2002, 05:36 PM
#19
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My first choice in pistons is Bill Miller, second would go to JE. Regardless who's pistons you get you need a custom jobbie especially made for boost, should be a 2618 alloy piston too.
-Mindgame
-Mindgame
10-18-2002, 05:59 PM
#20
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The skirts are elliptical ("barelled") so the pistons are round at operating temperatures, rather than room temp. The aluminum expands at a constant rate (look it up in Machinery's Handbook) w.r.t thickness. The thicker sections of piston will be narrower, since they will expand more when at operating temp.
What is the difference between F2 and F4 that makes F4 have more power? Is one a full skirt, and the other isn't? Why does the F6 make more power than the F4, and why would someone not want to run the F6 skirt design? I understand the elliptical shapes, but that is due entirely to piston expansion to get perfectly round pistons when hot. Thanks. I'm very curious. I guess I should also call JE/Miller/CP to see how they change the piston shape to account for colder thermal barrier coated pistons...
Also srp pistons use a F2 shirt design, a JE piston uses a F4 shirt their is a fair amount of power difference between the two. I used to always use the F6 design on Custon JE's it's alot more stable in the bore and makes alot better power than the F4.
10-18-2002, 06:37 PM
#21
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F2, F4, F6..... don't really know what they're referring to there. From what I know and have read, there are basically 3 skirt types. The strutted piston skirt design, which supposedly has the best strength to weight ratio.... usually a pretty lightweight piston, high revs etc.
The slipper skirt piston design which has more skirt contact area than the 'strutted'... supposedly a good long life piston that can handle light boost/nitrous etc.
The third is the full-round, which is the heaviest but it's also the strongest and supposedly will have the longest life.
When I see 'F2, F4, F6' I kinda think it has something to do with the slipper/strutted/full-round deal I just detailed. As far as different tapers go... I think that's pretty much left to those engine builders who spend alot of time doing R&D. Too bad Mr. Riddeck isn't here cause I'm sure he could tell us a few things about that kinda stuff.
-Mindgame
The slipper skirt piston design which has more skirt contact area than the 'strutted'... supposedly a good long life piston that can handle light boost/nitrous etc.
The third is the full-round, which is the heaviest but it's also the strongest and supposedly will have the longest life.
When I see 'F2, F4, F6' I kinda think it has something to do with the slipper/strutted/full-round deal I just detailed. As far as different tapers go... I think that's pretty much left to those engine builders who spend alot of time doing R&D. Too bad Mr. Riddeck isn't here cause I'm sure he could tell us a few things about that kinda stuff.
-Mindgame
10-18-2002, 08:35 PM
#22
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Originally posted by TAYLORMADE
RSKRAUSE
Do you have pistons already? J.E. is a fine piston but you should look into C.P. pistons they are made be Calvert. The three bothers made JE what they are today. They all left and started CP about 4years ago. They do alot of cup and high end pistons. JE was 79.00 a piston for customs and CP was 79.50 but they offered free pin fit(40.00 value). You should look at customs you'll get alot lighter and stronger piston helping you're rod situation out.
Also srp pistons use a F2 shirt design, a JE piston uses a F4 shirt their is a fair amount of power difference between the two. I used to always use the F6 design on Custon JE's it's alot more stable in the bore and makes alot better power than the F4. There is alot of different shirt designs that are better in certain apps and not in others.
CP piston all come with the accumulator between the top and 2nd rind which dampens the pulses between the rings that will unload the top ring causeing ring flutter and lose power. The acuumulator is standar on CP's but you pay more on JE's.
Any decent machine shop or engine builder will no about CP pistons although most indivuals don't.
I believe you shouldn't have any problems with the mod rod as your rpm are extremely low.
CP should be able to build a piston around 410 grams assuming it's a flat top w a 5.85 rod or longer but I'll bet you have 5.7 and a dish.
RSKRAUSE
Do you have pistons already? J.E. is a fine piston but you should look into C.P. pistons they are made be Calvert. The three bothers made JE what they are today. They all left and started CP about 4years ago. They do alot of cup and high end pistons. JE was 79.00 a piston for customs and CP was 79.50 but they offered free pin fit(40.00 value). You should look at customs you'll get alot lighter and stronger piston helping you're rod situation out.
Also srp pistons use a F2 shirt design, a JE piston uses a F4 shirt their is a fair amount of power difference between the two. I used to always use the F6 design on Custon JE's it's alot more stable in the bore and makes alot better power than the F4. There is alot of different shirt designs that are better in certain apps and not in others.
CP piston all come with the accumulator between the top and 2nd rind which dampens the pulses between the rings that will unload the top ring causeing ring flutter and lose power. The acuumulator is standar on CP's but you pay more on JE's.
Any decent machine shop or engine builder will no about CP pistons although most indivuals don't.
I believe you shouldn't have any problems with the mod rod as your rpm are extremely low.
CP should be able to build a piston around 410 grams assuming it's a flat top w a 5.85 rod or longer but I'll bet you have 5.7 and a dish.
Do you happen to have any contact info for CP?
Thanks again to you all for the valuable info
Rich Krause
10-19-2002, 02:00 AM
#23
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10-19-2002, 10:49 AM
#24
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I'm not sure what your compression height is going to be, but the closer to the dome the pin hole is, more attention to pin oiling is needed. Especially in a blown application where there is a lot of heat. There are different types of pin oiling other than your standard forced hole and possibly a "resevoir." You might want to talk to the manufacturer about this.
Concerning the skirt profile and a coating, yes the profile is different for parts that are(or will be) coated. It depends on the type of coating, application, location, etc. We have many, many different types of profiles for different forgings and applications, and they are numbered "similiarly" to what was previously mentioned. That's not really a factor though if you're ordering from a competent company. They will provide you with the best skirt for the application. Really high end racers actually R&D their own specified profiles, and change them accordingly for excellent results.
There are a few other factors that contribute to more power, less wear, etc. but that's a whole other subject!
Concerning the skirt profile and a coating, yes the profile is different for parts that are(or will be) coated. It depends on the type of coating, application, location, etc. We have many, many different types of profiles for different forgings and applications, and they are numbered "similiarly" to what was previously mentioned. That's not really a factor though if you're ordering from a competent company. They will provide you with the best skirt for the application. Really high end racers actually R&D their own specified profiles, and change them accordingly for excellent results.
There are a few other factors that contribute to more power, less wear, etc. but that's a whole other subject!
10-19-2002, 04:26 PM
#25
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MIND GAMES
The funny thing about Bill Miller pistons is they are done on an antique cam lobe shirt grinder. The machine came from true circle(old piston manufacture way before my time). There is some thing wrong or right with the machine because if they copy a design from JE or CP they make slightly better power at least in a cup engine. I know JE has probed the shirts and tryed to duplicate in on their CNC machines and can't do it. Something the machine is doing when it cuts the shirts seems to help power for sum unknown reason and nobady knows at least the last time I asked.
The F shirts are JE designs of shirts they use. They have alot more that the ones I said. They have a C3 shirt About a year or so ago they where trying for the cup guys hoping for more power. It didn't make any more power but was alot more stable in the bore legthening the ring wear.
The F2 on the SRP's in basically a round shirt that is part of the reason they are cheaper because the eliminate some machine time.
The funny thing about Bill Miller pistons is they are done on an antique cam lobe shirt grinder. The machine came from true circle(old piston manufacture way before my time). There is some thing wrong or right with the machine because if they copy a design from JE or CP they make slightly better power at least in a cup engine. I know JE has probed the shirts and tryed to duplicate in on their CNC machines and can't do it. Something the machine is doing when it cuts the shirts seems to help power for sum unknown reason and nobady knows at least the last time I asked.
The F shirts are JE designs of shirts they use. They have alot more that the ones I said. They have a C3 shirt About a year or so ago they where trying for the cup guys hoping for more power. It didn't make any more power but was alot more stable in the bore legthening the ring wear.
The F2 on the SRP's in basically a round shirt that is part of the reason they are cheaper because the eliminate some machine time.
Last edited by TAYLORMADE; 10-19-2002 at 04:28 PM.
10-19-2002, 07:27 PM
#26
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Taylor maid, 
Gotta tell ya... you're the one guy I know who's post I've gotta read at least three times. I think I got it now. This is a quote from the BME website......
"Bill Miller Engineering occupies a 20,000 sq. ft. manufacturing facility, warehouse, race car shop and executive office complex just north of the Carson City Airport. The state-of-the-art manufacturing facility is divided up into three sections, one for each of BME's three major products. A clean, well-lit factory area is loaded with the latest in machine tool technology including 15 Haas CNC Machining Centers and four Ikegai (considered the absolute best money can buy) CNC Turning Centers ."
I would assume the 'CNC Turning Centers' are for turning round stuff and other semi-round stuff including pistons. Could be wrong though.
There's something I'm dying to know though... how do you know BME's copying other people's designs?
Also, someone's been playing some nasty tricks on ya...... find out who reassigned that "k" key!
-Mindgame
Gotta tell ya... you're the one guy I know who's post I've gotta read at least three times.
I think I got it now. This is a quote from the BME website......"Bill Miller Engineering occupies a 20,000 sq. ft. manufacturing facility, warehouse, race car shop and executive office complex just north of the Carson City Airport. The state-of-the-art manufacturing facility is divided up into three sections, one for each of BME's three major products. A clean, well-lit factory area is loaded with the latest in machine tool technology including 15 Haas CNC Machining Centers and four Ikegai (considered the absolute best money can buy) CNC Turning Centers ."
I would assume the 'CNC Turning Centers' are for turning round stuff and other semi-round stuff including pistons. Could be wrong though.
There's something I'm dying to know though... how do you know BME's copying other people's designs?
Also, someone's been playing some nasty tricks on ya...... find out who reassigned that "k" key!
-Mindgame
10-19-2002, 08:39 PM
#27
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Re: Rod choice for hi-po/low rev setup?
Originally posted by rskrause
Currently I am running Lunati Pro-Mod rods with 220,000psi rod bolts. My present setup makes 733rwhp with a 6,000rpm redline. The setup I am planning for next year will be in the range of 900-1000rwhp on the juice and ~650-700 with just the blower. The nitrous will be used exclusively at the track. The new setup will not be revved any faster than now - 6,000rpm max.
Do you think the Pro Mods will do the trick? $1,200+ for Oliver billet rods would add a lot to the cost. So I am hoping that the Pro-Mods will do the trick. They are supposed to be good for 750+hp, and I will exceed that especially when the high internal power consumption of a blower motor is considered. OTOH the setup is very low revving, and I am under the impression that a big part of the load on rods is from revs.
Currently I am running Lunati Pro-Mod rods with 220,000psi rod bolts. My present setup makes 733rwhp with a 6,000rpm redline. The setup I am planning for next year will be in the range of 900-1000rwhp on the juice and ~650-700 with just the blower. The nitrous will be used exclusively at the track. The new setup will not be revved any faster than now - 6,000rpm max.
Do you think the Pro Mods will do the trick? $1,200+ for Oliver billet rods would add a lot to the cost. So I am hoping that the Pro-Mods will do the trick. They are supposed to be good for 750+hp, and I will exceed that especially when the high internal power consumption of a blower motor is considered. OTOH the setup is very low revving, and I am under the impression that a big part of the load on rods is from revs.
Not that I want the piston discussion to end, I don't, but to at least temporarily veer back on topic, I noticed a few errors noted.Rich isn't presently using Eagle, the rods are Lunati. And....
don't compare turbocharging (Bell) with supercharging.
Also, your present rods are rated for 750(+) HP. Although, I've 'fought' with rod people B4, no, don't care for the (hp) type of rating system they use, it's still under your anticipated goal.
I'm quite sure you know that the 'abuse' rating is altered with the choice of bolts. Nevertheless, I would determine the total cost of the project with the anticipated difference for the rod upgrade, and ask yourself, for how much (price of rods, balancing and labor for any extra clearancing) do I want to risk the engine life? You are after all, stretching the limit of their intended use. Maybe call Lunati. Ask them to comment on how much they underrate their rods, and if they would assume the same risk.
OK, back to the piston discussion, I'm listening.
Last edited by arnie; 10-19-2002 at 08:43 PM.
10-19-2002, 10:56 PM
#28
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MINDGAME
I lost the k key some how!!!!!!!!!
The deal with them copying pistons comes from a friend of mine the runs the dyno at one of the major cup teams. I get alot of info from him. They aren't suppost to talk about whats going on in the shop, so I can't tell you what team he's with. But most teams will use one piston manufacturer and send it to another to have them try to make it better so they are always competing against each other. This way you have 2 or 3 people working to make them better.
When JE found something that made more power or was more reliable they (cup team)would send it to BME and BME would intagrate that into their piston and it would make better power than the JE consistantly. If BME came up with something it would go to JE.
I'm sure they don't do many of their piston on that old machine except for some of the cup stuff. My friends team had all of their done on the old machine because it made power. Maybe the other teams don't know this. I'm not real sure.
I didn't mean to make it sound like they copied JE's stuff and didn't come up with their own stuff.
I lost the k key some how!!!!!!!!!
The deal with them copying pistons comes from a friend of mine the runs the dyno at one of the major cup teams. I get alot of info from him. They aren't suppost to talk about whats going on in the shop, so I can't tell you what team he's with. But most teams will use one piston manufacturer and send it to another to have them try to make it better so they are always competing against each other. This way you have 2 or 3 people working to make them better.
When JE found something that made more power or was more reliable they (cup team)would send it to BME and BME would intagrate that into their piston and it would make better power than the JE consistantly. If BME came up with something it would go to JE.
I'm sure they don't do many of their piston on that old machine except for some of the cup stuff. My friends team had all of their done on the old machine because it made power. Maybe the other teams don't know this. I'm not real sure.
I didn't mean to make it sound like they copied JE's stuff and didn't come up with their own stuff.
Last edited by TAYLORMADE; 10-19-2002 at 11:04 PM.
10-20-2002, 02:14 AM
#30
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From Oliver's web site:
Q: How much power will your rods take?
A: Connecting rods do not break due to horsepower, they fail due to tension loads. Heavy pistons, long stroke cranks and high RPM will actually pull a connecting rod in two. The goal is to select a rod that will handle the tension loads produced by your engine combination.
Very interesting! Anyone know the math to calculate peak and average tension loads on the rod? This statement implies that hp is NOT the determining factor but the engine geometry and rpms. If this is so, my new combo should be fine with the existing rods as the rev range and weight of the piston/ring package will be the same, right?
Rich Krause
Q: How much power will your rods take?
A: Connecting rods do not break due to horsepower, they fail due to tension loads. Heavy pistons, long stroke cranks and high RPM will actually pull a connecting rod in two. The goal is to select a rod that will handle the tension loads produced by your engine combination.
Very interesting! Anyone know the math to calculate peak and average tension loads on the rod? This statement implies that hp is NOT the determining factor but the engine geometry and rpms. If this is so, my new combo should be fine with the existing rods as the rev range and weight of the piston/ring package will be the same, right?
Rich Krause
Last edited by rskrause; 10-20-2002 at 02:32 AM.