PalmettoZ Posted April 8, 2009 Share Posted April 8, 2009 In my 3.1L motor that I am building with a V07 crank, I had it lightened by turning down the counterweights (knife-edged) and would like to take it one step further with milling holes in the rod journals. Just curious if anyone here has done this and if so what diameter hole they milled (or drilled). It appears to be possible to do but would require repluging the oil galley hole inside the newly drilled lightening hole. Seems like this could remove quite a bit of material off of the crank. Quote Link to comment Share on other sites More sharing options...
woldson Posted April 8, 2009 Share Posted April 8, 2009 You running a lighten flywheel? Probely cost less and gets rid of alot of weight. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted April 8, 2009 Share Posted April 8, 2009 YGood luck. Knife edging, or lightening the throws, will take alot of stability out of the crank, at certain harmonics. How light are your pistons? You should be able to get a 89mm bore piston down to 285 grams bare. That would be alot better area to concentrate on. LIsten to this engine rev, and this is a BONE stock V07 crank. And the tach reads correctly, according to MS. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 8, 2009 Share Posted April 8, 2009 Bit of overkill there IMO. There is far more weight in your Flywheel, Pressure Plate, Driveshaft, Axles, and Road Wheels/Tyres that will affect revving far more than the tradeoff of durability in trying to take more weight out of the rod throws! Everybody raves about their 11# flywheel...when they hang a 15# pressure plate off of it! Never made sense to me... If you wanted crank work, why knife edge when you could have cut the throws down completely and balanced the stub-counterweights (which now won't splash in oil and create windage) with Mallory-Metal? Same total weight, with far less moment of inertia, stability and quicker revs with less lost to windage... Oiling through the rod journals may make hollow rod journals a bit impractical as well. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted April 8, 2009 Share Posted April 8, 2009 http://www.circletrack.com/techarticles/ctrp_0504_engine_balancing_tech_terminology/piston_rod_crank_balancing.html For those now going ``wtf is mallory metal?'' Dave Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 8, 2009 Share Posted April 8, 2009 LOL, sorry... ever since I saw a Ferrari Crankshaft naked and made the revelation "ohhhhhhh...!" Quote Link to comment Share on other sites More sharing options...
PalmettoZ Posted April 9, 2009 Author Share Posted April 9, 2009 You running a lighten flywheel?Probely cost less and gets rid of alot of weight. Hey Woldson- Yep, got a Centerforce aluminum flywheel already. Good point on shedding weight. Quote Link to comment Share on other sites More sharing options...
PalmettoZ Posted April 9, 2009 Author Share Posted April 9, 2009 YGood luck. Knife edging, or lightening the throws, will take alot of stability out of the crank, at certain harmonics. How light are your pistons? You should be able to get a 89mm bore piston down to 285 grams bare. That would be alot better area to concentrate on. LIsten to this engine rev, and this is a BONE stock V07 crank. And the tach reads correctly, according to MS. Hey 1fastZ- They are stock 89mm flat top ITM pistons with large valve reliefs that I cut into them on a mill. I know they are fairly heavy but I didn't have access to a CNC mill to do the lightening on each one. My crank was balanced after it was lightened, and I don't plan on taking the motor over 7500 RPM. Your motor does sound sweet, thats for sure. Quote Link to comment Share on other sites More sharing options...
PalmettoZ Posted April 9, 2009 Author Share Posted April 9, 2009 Bit of overkill there IMO. There is far more weight in your Flywheel, Pressure Plate, Driveshaft, Axles, and Road Wheels/Tyres that will affect revving far more than the tradeoff of durability in trying to take more weight out of the rod throws! Everybody raves about their 11# flywheel...when they hang a 15# pressure plate off of it! Never made sense to me... If you wanted crank work, why knife edge when you could have cut the throws down completely and balanced the stub-counterweights (which now won't splash in oil and create windage) with Mallory-Metal? Same total weight, with far less moment of inertia, stability and quicker revs with less lost to windage... Oiling through the rod journals may make hollow rod journals a bit impractical as well. Hey Tony D- Didn't think about that one, good idea though. At this point I have been doing the work myself, and just thought I might finish up with a little more lightening. I think it is overkill at this point and will just go ahead and get it together and running. Thanks- Quote Link to comment Share on other sites More sharing options...
1 fast z Posted April 9, 2009 Share Posted April 9, 2009 I got these down to under 300 grams all on a manual bridgeport. WHen you concentrate on the piston, you make the rod stronger, as well as the crank, wrist pin, etc. You also are accelerating and decelerating that mass with each and every RPM, therefore more HP. Quote Link to comment Share on other sites More sharing options...
woldson Posted April 9, 2009 Share Posted April 9, 2009 Hey Woldson-Yep, got a Centerforce aluminum flywheel already. Good point on shedding weight. Could not afford, just lightened a 240mm stocker. Wanted to see if it really made a difference,,,,and Yes it DID! And I only took off 6.5lbs or so. Should of done little more, but safty frist! Hey Tony, yes lightening the flywheel, heavy pressure plate, then bigger rims!!! teehee. Starts to defeat the purpose abit. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted April 9, 2009 Share Posted April 9, 2009 Just for reference. A lighter flywheel, does nothing for HP to the ground. Talk to bonniville racers, and you will findout what and what does not matter for all out HP. It makes it rev happy, for an autocross car or what not, but no increased HP. Same with a lighter drive shaft. A piston being lighter does help though. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 9, 2009 Share Posted April 9, 2009 Just for reference. A lighter flywheel, does nothing for HP to the ground. Talk to bonniville racers, and you will findout what and what does not matter for all out HP. It makes it rev happy, for an autocross car or what not, but no increased HP. Same with a lighter drive shaft. A piston being lighter does help though. Er.... uh.... We picked up 3mph at ElMirage on Convo-Pro rims. Another 1 mph from an Aluminum Driveshaft. Horsepower 'increases' you are speaking of don't directly relate to that kind of speed increas on the salt, but decreasing rotational inertia in the driveline DOES pay massive dividends. We didn't go with carbon fiber drveshaft because of the $$$ and paranoia. Our flywheel, clutch, and pressure plate assembly weighs less than most people's clutch cover. And on top of that it's reduced diameter for less moment of inertia. If you think people at Bonneville are running stock weight flywheels for some 'horsepower advantage' you are sorely mistaken. "Rev Happy" is the name of the game. The ability to accelerate the mass moving the power to the ground. Every ounce there reduced makes for quicker revving when in gear. And that translates directly to faster acceleration, and therfore quicker achievement of terminal velocity. Do all you wish with lightening the pistons, but if you are running a heavy flywheel at Bonneville, you're concentrating on the absolutely wrong portion of the equation. SCTA 17 World Records: F/PRO, F/GALT, F/GCC Bonneville, El Mirage, Muroc:burnout: Quote Link to comment Share on other sites More sharing options...
1 fast z Posted April 9, 2009 Share Posted April 9, 2009 Here is a post here tony you can make those comments about LSR on http://www.landracing.com/forum/index.php/topic,5854.0.html Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 9, 2009 Share Posted April 9, 2009 You base that on one response you got? Our testing on the short course you mention has proven otherwise. You should not be 'shifting near the wall', you should be dragraced to almost near top speed before the end of mile one---where decreased rotational inertia helps you UP to speed. Then you will inch up making another 1 or 2mph through mile two, and maybe more or less the same (if you are very lucky) through mile three. Unless you are grossly underpowered, there wont be much 'shifting' after mile marker one. And for sure mile marker two! You are not planning on running a 50cc two-stroke streamliner, are you? After getting up to near top speed rotational inertia beecomes your friend. Problem is, that is more applicable to the long course where you are still accelerating through mile three, and at the same point you are at mile 1 in the short course. While accelerating hard, less mass is your friend. Once to speed to maintain it, mass again becomes your friend. in other words, less helps you more than more. If you have a humongo powerplant, maybe running heavy things will help you. But with lower horsepower cars (under say 5-600hp) the less rotating mass you have the better! The HP you 'gain' from lightening your pistons will be on the order of say 20 hp to be more than generous. It will do NOTHING significant for you in terms of top speed, as over 150mph you need MUCH MORE than that to make a difference. But lower rotational inertia on the wheels and flywheel will accelerate you quicker to near top speed, which is FAR more important than a measly 20HP. Do ANY calculation you want and justify how much more top speed you will get from 20HP at 150mph on a car like the Z or a 58 Buick Roadmaster for that matter! I noted the guy said he did 'research' and 'from what he was told'.... Whereas I posted concrete numbers resulting in the changes we made. I see that as a difference in the two posts. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted April 9, 2009 Share Posted April 9, 2009 I know lots of guys who hold records (current records BTW) anywhere from 125 MPH through 220 MPH and have guided us on building our Bonniville car. That is where I get my info from. You can gain ALOT more than 1-2 MPH in the last couple miles of the short course. Im not saying your wrong, or them, Just from what the experience shows from them is what I go by, as We are just learning in the LSR side of things, as we have been drag racers and dirt track racers. I do urge you to post your thoughts on that thread though. Quote Link to comment Share on other sites More sharing options...
woldson Posted April 10, 2009 Share Posted April 10, 2009 I would like to say more here, but things are getting a little heavy for me, or, lack there of;) Great info though! I will say this, without any other changes to my car, lighten and balanced the apperent tourqe of the engine certainly is refective in the smell of rubber I get from driving the car like I always do. Even though I have not increased power in any way at the engine, the translated power though the drivetrain to the pavement is VERY noticeable. (acceration, throttle respone). I've posted in several threads, cuse even though it made sense to me, it really was quite surprising, plus I did not do any other "while I'm at it". There is going to be a dyno day coming up, so maybe, just maybe the results will be noteable. OK so I could not resist, sue me:) Quote Link to comment Share on other sites More sharing options...
johnc Posted April 10, 2009 Share Posted April 10, 2009 A lighter flywheel, does nothing for HP to the ground. Absolutely right. A lightened flywheel or lightened reciprocating parts do not increase horsepower at all. The engine will make the same horsepower at steady state rpm as it did with the heavier parts. Less mass and reduced MOI increased the rate of acceleration, which is what we're concerned with. Quote Link to comment Share on other sites More sharing options...
boardkid280z Posted April 14, 2009 Share Posted April 14, 2009 Absolutely right. A lightened flywheel or lightened reciprocating parts do not increase horsepower at all. The engine will make the same horsepower at steady state rpm as it did with the heavier parts. Less mass and reduced MOI increased the rate of acceleration, which is what we're concerned with. OK, so does it give you more area under the curve? Or does it affect the torque or what? I mean, it should be measurable on a wheel dyno if it makes a difference in the rate of acceleration. Basically, though, it will make your car faster, even though it doesn't increase your horsepower. Right? Quote Link to comment Share on other sites More sharing options...
woldson Posted April 14, 2009 Share Posted April 14, 2009 The hp/torque of any given engine has to accelerate itself, clutch assemblies, transmission parts, drive shaft, differential, more dive shafts, wheels and the car itself. This includes all friction surfaces in all the moving parts. Although there are advantages to all the parts in unison, they also offer there disadvantages. I.E, standard tyranny vs. auto. Each has its advantages and disadvantages, just depends really on application. Will it show up on a dyno, maybe it will in faster torque increases, as far as an over all number, not sure, can't visualize. It's not like you loose hp to the ground when you have a head wind. Quote Link to comment Share on other sites More sharing options...
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