Merry Christmas ALL!
J, When is the Apex trackday? My dad got me a few laps around cayuga in an exotic (F430, Gallardo, or AM) and I’d like to do a bit of track driving before then…
Oh and this post was Grrrrreeeeaaaaat! lol!
Are you crazy? My car is faster than yours. I’m waiting for you to catch up to my stock 12.75 @ 108.
P.s. If I get a jhm supercharger, low 12s/high 11s will be a warm up, shifting at 6000 and rolling off the line like going to get groceries. They’re using a vortech cfuge capable of ripping the rods right out of the engine. Capable of 1200+ cfm. I know you don’t agree with their choice or tts’ choice of a cfuge (I will pas that on… But I think tts and their easy 125 mph trap means at least they’ll stick with it lol) but a high revving motor will just go to lunch with it.
bear: apexdriving.ca They should post a schedule for 2013 at some point, but they probably won’t start until ~may. TMP will be open in April, as usual, but I guess Mosport is very, very close to you… http://www.6thgear.ca/ does mosport too, but will be a lot more STIs, civics, etc. I’ll go anytime…
Sak, that’s what I wanted to hear…(except the part about throwing rods!)…do it!
Not to derail this thread, but was there any consensus on what type of SC APR was using after they posted the pictures? Is it the 1900? It certainly looks like a 4-lobe TVS Roots style blower to me. I spent all evening nerding out on SC information since I didn’t really know a whole lot more than high level general information.
I had to go through this http://en.wikipedia.org/wiki/Roots-type_supercharger to get a loose grasp on the math and physics behind the performance maps you were posting in the other speculation thread.
I found this page comparing the TVS to Eaton’s 5th gen blowers interesting and informative even if some of it was above my head. http://www.smokinvette.com/corvette/articles/eaton-tvs-supercharger/
I wonder where the information for this table came from and what data was used to create it.
This thread had some nice pictures and commentary on a TVS 1900 for a Ford and compared it to the stock blower. http://vmptuning.com/forum/showthread.php?t=746
As far as clutches for the MT guys, Arin said in the AZ thread:
[quote]I’ll have something for you guys. Don’t worry.
[/quote]
I’m saving up for it now, but it’ll be tough when my girlfriend has lots of other plans that she feels are a higher priority for my money than this is. I’m working on her every day now to convince her that I can save money for a down payment on a second house and still afford this.
-Skid
The recommended displacement ranges are aways a bit vague. One of the tuning companies… Pes I believe… Used that as their basis for choosing the Eaton m90 for the rs4 supercharger kit they were selling for $12,500. Reality is that displacement doest really work in this situation because a 4.2 rs4 with near 100 percent volumetric efficiency and an 8250 rpm red line, making 420 hp is not going to beiinefficientficientit as much as a 4.2 that makes 280 hp and revs out to 6250.
The Eaton m90is good for about 450 hp at the crank before it is maxed out. Think about that now. The rs4 makes 420 hp stock lol. When many of the guys on this site openly questioned pes on this poor fit, they cited the recommended displacement chart (written in 1991) on eaton’s website to justify their choice. When asked about VE and CFM capabilities… they went quiet. When asked why they went quiet, they had moderators lock threads. When new threads were started asking for answers, they used their paying advertiser power and had people banned rather than answer (a5oc).
The funny thing is the jaguar 4.2 that made nowhere near rs4 power and red lined at 6500 rpm… When they supercharged the R cars, jaguar used an eaton m112, not the m90.
Simply put, pes didn’t do their homework.
So bottom line? Ignore the ‘recommendation’ based on displacement and focus on efficiency and cfm capabilities of the supercharger when deciding which one to use.
. 4.2 was right in the heart of the graoh
yeah sizing based on displacement only misses quite a bit of the story. eaton is also making recommendations for oems, not performance modifications.
Eaton publishes the compressor maps…if you can use PV=nRT it’s pretty easy to see where we fit in. I’ve posted the maps many times on AZ already…look in the year-old “Stage III speculation” thread.
Yeah, I was looking at that one this morning. I saw in this image that the 2.0 mark on the graph was 15psi.
http://upload.wikimedia.org/wikipedia/commons/d/dc/Roots_Supercharger_efficiency_map.jpg
Is that psia or psig? When you guys are talking about 18-22 psi of boost, are those values in psig?
EDIT: Just re-read your post here http://www.audizine.com/forum/showthread.php/517989-Teaser-APR-3-0-TFSI-Stage-III-Supercharger-System?p=8277437&viewfull=1#post8277437 and saw psig.
How do you determine the volume of air that needs to flow through the SC (y-axis) relative to the engine displacement and calculate HP from it?
Don’t feel obliged to educate me if you’re bored with discussing this topic. I’m a little late to the topic and am just now beginning to understand it enough to really get interested in the speculation.
-Skid
Actually, I started reading this http://www.ehow.com/how_7953457_size-custom-supercharger.html Their math has you start with your naturally aspirated horsepower and then assumes 7-9% HP gains per 1 pound of boost. Can I use the same calculations, but start at 300ish HP and 14-15 pounds of boost to calculate the same numbers going up from there?
If so, wouldn’t 22 psig put us around 450 whp (if the car was getting 300 whp at 14-25 psig of boost) assuming a 7% increase in HP per additional psi of boost.
I think I messed up trying to use their math to come up with the air flow and convert it to m^3/hr and also had no idea of what the volumetric efficiency of our engine at 7k RPMs was.
-Skid
150cfm/100bhp, boost is going to depend on restriction after the blower. the compressor maps are in absolute pressure terms, 5psi boost = 5psig = 19.7psia = 1.34 PR
The speed/density system our ECU uses is more or less based on a model of the volumetric efficiency of our motor…it takes RPM, absolute pressure in the mani, and temperature and computes an airflow in kg/hr based on a map. That map already has the corrections (volumetric efficiency) for how much air the cylinders will actually draw at any given pressure, per stroke.
So if you simply log the maximum flow, and damn I’ve seen a lot of logs for our motor, you see that Stage II people can draw 1400 kg/hr at 2100 hPa. hPa is nice because it’s an absolute pressure unit, nicer than dealing with psig which doesn’t take into account the atmospheric pressure - hPa tells you the total amount of air flowing into the motor.
Use pV=nRT to get about 1150 m^3/hr, taking into account the density of intake air around 35 deg C. After about 12 sec of acceleration, that intake air is between 50-70 depending on conditions (and if you have a CPS) so the flow drops to 1050-1100 m^3/hr.
Plot that on our TVS1320 compressor map, and assuming a pressure ratio of a little over 2.1 (i.e. 2100 hPa, or a little over 16 psig in sea-level conditions), What you get is an efficiency and blower speed. That will tell you if you are in the ballpark (you’re aiming for decent efficiency). Plug in different flows and pressures, and see if you’re still on the map. Here’s a stage Ii log if you need one:
https://docs.google.com/spreadsheet/pub?key=0AkzIv9fePyQsdDNzbTlqcVFUOE5jWmlFNlQyamxkV3c&output=html
Try it from 3000 rpm on up, you’ll more or less have a straight line from 500 m^3/hr and 2.0 PR to around 1150 m^3/hr and 2.1 PR.
Plug the same numbers into a different blower, i.e. TVS1900, at the same PRs and flows, and see if you are still in the ballpark (we are). We’ll actually be a bit more efficient, at stock boost levels, and at the top end, the TVS1900 would only have to spin about 73% of the speed of the 1320. The extra power to drive the bigger blower would likely be a wash at stock boost levels (a guess because unfortunately they don’t publish power to spin the blower at different flows/PRs).
Now consider we’re instead going to drive this big blower to much higher PRs and flows. You can see there is lots of headroom now, whereas we’ve pretty much reached the end of the chart on the 1320.
*As a side note, you can only rely so much on the manufacturer’s compressor maps - lots of people ignore them. FYI, our numbers based on the compressor maps are off in the real world, since stage II cars seems to push only 1150 or so m^3/hr, at 2.1 PR, but they are spinning at a much higher blower speed (20000+ rpm, off the chart).
**And another side note, notice I’ve said nothing about power (although beemercer’s rule of thumb works pretty well for this car for bhp). We are only designing for airflow, after that power is made by tuning for AFR and ignition advance.
***Yet another side note, it is likely that anyone designing for a 1900 blower on the 3.0T (APR?) will:
a.) rely on the recycle valve to control boost levels at low RPMS to avoid going into stall at the upper left corner on the map
b.) rely on the recycle valve to control boost levels with pump gas, since it’s unlikely the motor can handle 22 psig on pump gas reliably, without knocking
c.) start with a larger pulley for street trim, which would spin more efficiently, and maybe later offer a smaller off-road pulley for those willing to sacrifice longevity and blower efficiency for more top-end power.
And if you fill the CPS with the proper mixture of coolant and water (50/50 or 40/60)… lol
HAHAH that is a must
jspazz is it still totally off topic if its an RC car supercharger? ;D
http://images.rcuniverse.com/forum/upfiles/61620/Pl32650.jpg
this is the new RC and Fish tank thread, so it’s 100% on topic.
That is retarded by the way. The little heat exchanger is awesome.
jspazz called me out on az to not turn it into a RC car thread so i thought this might be on topic to post there lol
It actually looks like a intercooler upgrade…that’s relevant here
Here’s a question…
If a b8 s4 runs a Revo race gas file, on excellent 110 octane fuel, and also runs an APR pulley with it, what will happen
A) 11 second glory
B) 12 second sad faces
C) 12 second sad faces + catastrophic engine failure + maybe transmission failure for good measure + a face palm
If it is C, what do we think caused the catastrophic engine failure. Or, I mean, what could cause it (since this is only hypothetical).
Boost and power levels that the cast rods can’t handle?
Timing levels that the cast rods can’t handle?
Boosted power and timing working together to kill the car?
Piston failure?
I don’t know Saki. I don’t know anyone who’s done that.
I’ve seen logs of an engine failure on REVO with a stock pulley at 1800 hPa. Didn’t you see the logs? Maybe Prime or Tsivas can send them to you.