Printable View
8" rengade crank pulley and a 3.25" blower pulley? That comes up to 54025 impellar speed. Is that too close to the max 55000? Will that be pushing it? How bad would it be to use an 8" crank and a 3" blower pulley = 58528. I know thats overspinning it, but not by much. I guess what I am asking is what the maximun "safe" impellar speed would be with a shift point of 6200. It is a newer 2 belt Novi.
You should also consider, turning the N1000 at the max speed, if you will cross the point of diminishing returns well before the impeller reaches terminal velocity?
I haven't seen a compressor map for the N1000 (yet - still looking for one), but if it is anything like the s-trim, by the time you get up into the upper 40k rpm range, the efficiency of the compressor drops way off, and the result is, you aren't moving a significant increase in air mass, but you do start to needlessly beat up (heat) the air, which in turn demands less timing &/or richer mixture, so you end up with same or less net horsepower than you'd make keeping the compressor closer to the efficiency sweet spot in the compressor map.
Here's the s-trim map:
http://www.vortechsuperchargers.com/...-trim_map.html
The N1000 should look very similar in shape, just picture everything shifted to the left slightly, i.e. max airflow of 850 cfm vs 1000 cfm for the S-trim.
These maps can be confusing. The most important trend to pay attention to IMO is the line on the bottom right, thet 65% efficiency line. Notice how the flow increases dramatically at first, but then as impeller speed goes up, the flow stops increasing even though the pressure keeps rising. [edit] and as it goes past 45000 rpm the mass airflow actually DECREASES as pressure increases! [/edit] Adding pressure (boost) without adding mass airflow is a bad thing, you are basically getting the same amount of air at a higher temperature. :weird:
WOW! I did not even consider these factors. I was under the assumtion the faster it spins, the more boost. I am not really sure how to read that chart?? :freaks: I kind of gather spinning it any more than 45000 is not accomplishing anything? Does anyone have a silmilar chart for a Novi 1000 or know the threshhold when the compressor becomes inefficient. I am thinking the 50000-51000 seems to be a safe range where most run either a 8" renegade crank or a 3" blower pulley. Any more input? Please chime in.Quote:
Originally Posted by fanglemeister
Well i ran the 8" crank with the 3.5" blower pulley and it ran very well. I wanted to try 3.25 pulley but i never got around to it. I always thought it would be the ultimate setup. Have you ran the 8" crank yet? It may make as much power as you need all by itself.
I just called Paxton and they confirmed MAX impellar speed is 55000. They said on a Novi 1000 the most effecient impellar speed is ~50000. After that it drops off. So, I guess those with the 8" crank and 3.25 sc pulley may want to rethink your pulies 'cause according to Paxton it is inefficient at that rpm. :confused:
I had a 3" SC pulley ordered, but its a long story and we won't go there. SO now I probably will get the 8" crank to keep my warranty alive. What size acc. belt now that the crank pulley is 4.75 underdrive? What size 8 rib SC belt will it require and is that 8 rib belt a common auto parts store belt?Quote:
Originally Posted by regattacoupe
That makes sense, although they probably meant it flows maximum air mass at 50k, because the maximum adiabatic efficiency is probably more like 37000. It is hard to determine what's what without seeing a compressor map for the 1000. The Vortech s-trim map definitely shows it pushes the most air mass at 45k, and max speed for that unit is 50k, so it probably makes sense the Novi would also move its maximum air mass @ 5k under max impeller speed.Quote:
Originally Posted by 92 coupe
In an ideal situation your Novi 1K should be pullied to hit maximum mass airflow (50k) right at the very same rpm your intake manifold and cam are supposed to hit their peak flow potential.
For instance running a mild street cam/intake combo, cam & intake peaks both setup for @ 5500 rpm, you should probably pulley the novi to hit 50k @ 5800 rpm, and then not even bother winding it up much past 5800-6000. OTOH for a healthier street/strip combo that is supposed to pull strong to 6200-6400, then you should pulley the Novi to hit 50k at 6200 as well to avoid overspinning it, and shift at 6400 (eec/tuning allowing). What the compressor map shows is, no matter what boost it creates at what rpm, it is still only going to move 850 cfm max. The psi boost number is only an indication of intake restriction &/or heating the air, not increased mass airflow.