My94RedZ28A4

I'm not flaming or anything, but isn't Iron a Body-Centered Cubic (BCC)?

http://www.jwave.vt.edu/crcd/archive...s2/farkas2.htm

Or, does the inclusion of carbon/zinc, etc... rearrange the atomic structure in such that it becomes a FCC?

I remember hearing that FCC's are more durable, but also not a "tough" metal, like gold, copper, etc...

96TAWS6

Yes, iron is BCC at room temperature. The way I posted it made it sound like it was FCC. Iron does become FCC in the form of austenite at around 900*C or so depending on the amount of Carbon present. When the mixture is rapidly cooled, the carbon atoms become trapped in an iron BCC structure, which is steel.

RHC

sleeperz28

Rich, just curious why you want to only rev to 6K. With that manual I think you would want to stay in the power band a little longer so you have time to shif. That is why i put solid roller in...

JeffB_94Z

trey wrote:

"from what i understand billet stetches ESPECIALLY under heat (2 types of forced induction)
I didn't know that when I bought my rods.
I'm sure someone makes a forged rod strong enough"


George Baxter was originally running oliver non-billet rods in his motor... after a while he pulled them to find that they had stretched... they have since been replaced by oliver billet rods and to my knowledge he's had no rod-related problems... it wouldn't make sense that the billet rod would be the top of the oliver line if non-billet was better...

rskrause

F-bud: the answer is fairly long. But it comes down to my idea of the best way to set up a centrifugal car for street/strip use. In my setup I use a small cam (214/224) and have pullied the blower way up and am consequently limited to 6,000rpm. That's the down side. The upside is that I see usable boost as low as 2,000rpm and ~5lbs as low as 2,500rpm (which is as low as I would ever crack the throttle anyway). As a turbo guy you can relate to that, right?

This setup has done everything I expected of it, and I see no reason to go to a high rev setup for the new buildup. The purpose is to have a stouter bottm end that will stand up to a larger nitrous shot. Of course, nitrous works the same at low rpm as at high, as long as the motor can stand the very high cylinder pressures you get from activating it low rpm. Currently I am using a 200hp shot at 3,300rpm and plan to go to 300hp or more, though I will use a progressive controller of some sort.

To my way of thinking you are just increasing frictional losses by spinning a blower motor to high rpm. Unlike NA, you aren't dependent on high rpms to pump a lot of air.

Just IMHO.

Rich Krause

Z28tt

Rich - This is a little off on the subject, but it's piqued my interest. If at 6000 rpms your intake stroke is 10ms long, and at 3000 rpms, it's 20ms long, won't twice as much nitrous and fuel get into the chamber, for a much larger cylinder pressure? I guess HP might remain the same (more torque at lower rpm = same hp as less torque at higher rpm, and torque/cylinder pressures are directly related). Another thing that's been mentioned before is too much cylinder pressure. The big boosted turbo folks have been running semi-large cams to bleed off cylinder pressure at lower rpms, otherwise there is too much time to force in air/fuel, and the cyl pressures get out of hand. This is all heresay, but I've heard it from several sources. <shrug>

Andris

JeffB_94Z

in Rich's case (or anyone running a blower + nitrous) i think it balances out pretty well.. in the lower rpm range there isn't as much boost because the blower isn't spinning fast yet... however there is much more torque gained from the nitrous... as the nitrous-induced torque falls off, the boost-induced torque comes on... the combination of the two should provide a fairly flat torque curve...

on my car, for example, which redlines at 6500rpms (15psi) i only see about 6psi of boost at 4000rpms (where my converter stalls on the line)... between 4000 and 4500rpms the power takes off like crazy (another 90rwhp)... so having just a small 50hp shot come in at 3800 is giving me a big boost in that mid range... as the boost comes on, the 50 shot gets to be less and less of a contribution, but at the point where i'm only making 400hp its a big deal...

with a turbo car you would have a different situation, and i would think that you would be limited by peak-torque cylinder pressure since you could have full boost and full nitrous at one point...

rskrause

Andris: this aspect of nitrous is commonly misunderstood. Even by some who use it! Keep in mind that BMEP is inversely proportional to rpm (if hp were constant). When you further consider that nitrous adds the same amount of power no matter the rpm, you can see that for a given nitrous shot the increase in BMEP due to the nitrous (and peak cylinder pressures as well) will be twice as great at say 2,000rpm as it is at 4,000. That's why bringing in a large nitrous shot too low tends to break parts.

With respect to cam, I can see where a very high boost turbo setup might need to have enough overlap to bleed off some cylinder pressure at low rpm. It's kind of comparqable to nitrous. A turbo can produce full boost at low rpm, right? So at low rpm there may be an excessive increase in cylinder pressure. A centrifugal is relatively weak at low rpm, even when set up like mine. So there's no reason to run enough overlap to bleed off pressure at low rpm. And of course, such a cam will lose some boost at high rpm. If you are trying to get the max out of a relatvely small blower (as I am) this is a big no-no.

Hope that made sense.

Rich Krause

OldSStroker

I like the way you think, Rich. I'm guessing it works well even off the bottle. Although I'm not a NOS fan, your approach looks good.
So does your physics.