Made it to the dyno

[Clifton]

So 600 hp on stock rods is possible as long as it is not an endurance road race car being spun at 6-8k for hours on end. Perfect, as Bryans car is a street car.

 

If I had the financial backing Electramitive had I would not use stock rods either or even cranks. Money makes those decisions alot easier.

 

I may be wrong, let me know, but I would think that Bryans engine only seeing 17 psi would be less detrimental to longivity than say another engine seeing 22 psi (mine) and making less horsepower but similar torque. The load on the internals would be the same at peak torque, his just breathes better up top making more power. I would also think 22 psi would easily have him to 600 crank. I ran 22 psi when I road raced and never had a rod failure and it saw some revs.

[Gollum]

I was thinking about the same thing clifton, but I wasn't gonna say anything as I was gonna let the more experienced people chime in.

 

If it's torque transfered into load that kills trannies and diffs, why wouldn't it be torque that kills internals? If I'm correct in that then maybe running a dyno in 4th gear is more likely to break something than in say, 2nd. Maybe I've got my logic all screwed up though.

 

At any rate I'm more excited about this project than ever and I really don't wanna see it all end because of a rod failiure that could have been prevented.

[Dan Baldwin]

At any kind of "reasonable" boost levels, the snap-through acceleration of the piston at TDC at redline between exhaust/intake is a more significant tensile (i.e., crack-inducing/growing) load on rods than the compressive forces from the big kersplosion shoving the piston down during power stroke.

 

p.s.: late to the party, holy FRICK what an awesome build! My favorite post: $3200 spent plus a TON of work.

 

OUTSTANDING

[1 fast z]

Take and tie your car to a tree, and if you could have 4 wheel drive and 100% traction, then rev it to 10k and drop the clutch, this simulates if your car weighed TONS, see what happens.

 

 

Then take that same car and un tie it.

 

 

Less FORCE on the trans/diff/axles.

 

 

Take a go kart with 500 hp, and all use a small dinky trans, will work fine. Take that same motor and trans, in a 10000 lb car, and see if that trans last.

[1 fast z]

It all goes back to F=MA. Less mass, less force, I want a scientific/mathmatical equation showing otherwise, untill them, I will create my own equation to show the difference.

[thehelix112]

Ok let me break it down

 

M = weight of car

A = how fast car is accelerating

F = forward force acting on car, and a direct translation of torque produced by the engine and tyre traction.

 

Let us first off assume tyre traction is perfect (slip ratio = 0), and let us also assume the same engine is being used, thus F is the same.

 

If you change M, all you are changing is A.

 

It sounds like you're talking about M `magically' affecting F without a change in A. Show me how that works?

 

Dave

[hughdogz]

I may be wrong, but here is how I'm looking at it...if we're talking about breaking transmissions and rear differentials it comes down to shock loading, not a constant force or acceleration.

 

Say that you have a 500 HP engine and you drop the clutch on a 1000 pound car with no tire (or clutch) spin. I think it would be harder on the drivetrain (a bigger shock) to drop 500 HP on a 10,000 pound car under the same conditions.

 

I think this is basically what Brian is saying...in general lighter is better...less mass to accelerate is less force on the components.

 

Here is another analogy: Who would win a 400m dash...a fat guy or a skinny guy? lol...if it were a tie, I would think it would be much harder on the fat guy's bones (components) than the skinny guy's bones. Maybe it's not a perfect analogy, but this thread could use some more lightening up!

[Careless]

Somewhat of a good analogy, but if you slowly crept upto full-taught with the rope or whatever you're tying the car to the tree with, and then started a launch with the rope already very tight, the only thing that would happen if you got 100% traction is your clutch would just spin freely after your bumper or tow-hooks took the brunt of the launch along with the tranmission.

 

but your analogy does make sense... but there are way too many variables to tell for real.

 

not that you're gonna tie this car to a tree anyway, but whatever.

 

Take and tie your car to a tree

[1 fast z]

Yes, a shock load, if a roll is done, theres not much difference, thats why you break things on the line at the drag strip and not so much half track, although it can happen.

 

 

Take a 2000lb z to the track with slicks, then take the same drivetrain with a 3000lb z to the track with slicks, you will be harsher on the 3000lb car off the line, and more likely to break the drivetrain.

 

 

I am speaking from first hand experience fellaws. I dont just pull this stuff out of thin air.

[thehelix112]

Noone is arguing that a heavier car isn't harder on the drivetrain (atleast not me). I am arguing your reasoning. The reason is that the heavier car has more load on the tyres, which makes them less likely to spin, in addition to requiring more torque to move it.

 

Experience is worthless to us here if you can't explain it properly. Noone is going to take your word for it.

 

Dave

[1 fast z]

Where, am I talking about tires helix? I am talking MASS, thats always the varible I am talking about.

[COZY Z COLE]

Let's cut the ropes off the cars and get out of the forrest AND get back to the dyno subject of this thread.

 

 

 

LARRY

[1 fast z]

What do I know right. Well Ive always been the one to think and do outside of the box, if not, we wouldnt even have a twin cam L series head to talk about in this dyno thread.

 

 

But next time you go to the drags, take and put 1000lb's of lead in your spare tire well, and launch your car with 10 inch wide slicks at 8k RPM, lets see if your trans holds up.

 

 

But untill then, I will be installing the Z32 transmission, as the Z32's were the heaviest of the z cars untill 96, so nissan but a bigger trans for a reason.

 

 

Clifton and I were talking last night, were gonna go back to the dyno before the year is over, I will use the turbos one last time, and see what we get.

[zero]

Where, am I talking about tires helix? I am talking MASS, thats always the varible I am talking about.

 

As people have said before, no one is doubting that a heavier car will be harder on the drive train. And I certainly am not doubting your expertise, skill, or experience, all of which are clearly far above mine.

 

But F=MA isn't a robust explanation for the higher shock loads. By saying that F increases with M, you assume that A remains constant. This would undermine the advantage of bringing a lighter car to the track.

 

The force that breaks drivelines isn't the required force to accelerate the car, but the maximum applied torque before the tires lose grip. This is defined not by the weight of the car necessarily but by the weight on the rear tires. The traction of the tires has a positive, but not necessarily 1:1 linear relationship with the weight loading on the them.

 

Picture a Z with 1000lbs of lead directly on top of or in front of the front axle. It would require no more force for this Z to spin its tires than a standard Z, and thus would be no harder on the drive train.

 

A Z with 1000lbs directly on the rear axle would have significantly more traction as well as a higher traction to overall weight ratio. As a result the required force to spin the tires would be higher and thus it would be harder on the driveline.

 

 

just food for thought....

[thehelix112]

Where, am I talking about tires helix? I am talking MASS, thats always the varible I am talking about.

 

In chronological order:

 

You take a car that weighs 10,000 lbs, with 500 torque, and get sticky tires...

 

Take and tie your car to a tree, and if you could have 4 wheel drive and 100% traction...

 

Take a 2000lb z to the track with slicks...

 

 

Dave

[1 fast z]

MASS IS THE ONLY VARIBLE,

 

 

your freaking nuts man, Look up what a variable means PLEASE, DAMN.

[X64v]

Larry's word is law around here, so I moved this to another thread.

 

http://forums.hybridz.org/showthread.php?t=127908

 

As for this thread, back to our 5.126" rods.

[thehelix112]

Cool, back onto the topic of rods, I have no first hand experience, but do remember reading somewhere comments by someone more experienced than I that went like this:

 

Most rod failures result from oil starvation and the resulting heat buildup.

 

Taking that, and Tony's comments about elasticity and the resulting little, and big end deformations, it would seem plausible that if the big end becomes elongated, (in addition to heating it up), it would affect the oil supply with more oil leaking out past the points which are further from the crank journal. As I understand it larger clearances are a good thing as the oil flow (and hence cooling capacity) is increased, but I would have to guess that the additional flow and cooling capacity do not outweigh the additional heat in the rod due to deformation.

 

That, and ensuring that your crank is cross-drilled so the `centrifugal' forces aren't pulling the oil out faster than the pump can supply it.

 

I envy your machining shop, and skills 1 fast z.

 

Dave

[1 fast z]

Yes, elasticiy, or YEILD as they call it in the metal world, is a big factor. That also triggers back to lighter piston, less recipicating mass, equels farther away from the yeild point of the material. I will be the one to test the rods, as it seems, no one is running stock rods in HIGH hp applications.

[thehelix112]

Actually `yield' is point at which the material stops deforming elastically, and starts deforming plastically.

 

Dave