centri's - boost vs rpm

[Alter Ego Trip]

According to that it's not such a weird idea after all. I might give that route a try. I would like a little more low end power on the street.

 

[lito]

that would be really interesting. wouldn't that be inefficient as hell? not to mention the car would sound like a vacuum cleaner! but i love the concept. please update us on that one

As promised, here are the graphs, the boost graph is overlayed, the one that ramps is the exact same F1R setup (not the same engine but similar, more flow now, same cid, heads and headers, only difference is a 127550 now)

Added the power/torque curve, there is a deep that was corrected later on, this is on pump+meth.

Purple is normal run, cyan is the wastegated one.

We used a turboxs dial in boost controller. Would like it better tested on a duty cycle unit but was not the case.

 

[bigmachano]

As promised, here are the graphs, the boost graph is overlayed, the one that ramps is the exact same F1R setup (not the same engine but similar, more flow now, same cid, heads and headers, only difference is a 127550 now)

Added the power/torque curve, there is a deep that was corrected later on, this is on pump+meth.

Purple is normal run, cyan is the wastegated one.

We used a turboxs dial in boost controller. Would like it better tested on a duty cycle unit but was not the case.

sorry just got to see this (computer wouldn't open it up in iraq). that looks pretty interesting. as i understand it, the red race valve from procharger is somewhat adjustable. would i be able to create this same effect with a procharger and the red race? what i was thinking was hooking the bypass up to a tube (pvc or otherwise), monitoring air pressure from an air hose and then adjusting it to open up at 10lbs. does that seem like a dumb idea, or is my logic right?

 

[Full_Tilt]

You could pulley it down and install a wastegate that is boost controlled so you could flat the boost around where you want.

I'll have a F1R car on the dyno with this in thursday. Car is making 22psi up top and want to leave it at 13-14 so it can be used on pump.

In theory it works, and customer commented me that it does but I have to see it first.

This.

I have seen this work, Ill see if I can find the article.

The main problem is that you are limited on the speed you can spin the compressor, so you still cant overdrive it super high and have it bypassing a ton of air up top. You could never get a boost curve like a positive displacement compressor. But you can improve it significantly.

 

[bigmachano]

my deal is the p1 kit i bought used comes with a 3.7 pulley and i wanted to see if it were possible to limit the boost to 10 lbs to be safeish. i shouldn't be dumping too much air before 6000 rpm (based on my ricer-bench racing math) and i don't really plan on getting too high up in the rpms on a stock longblock anyway. this just seemed like a pretty interesting idea to pursue. i'll end up pussing out and getting the 4.0 pulley...

 

[19COBRA93]

I'm running this setup.

I have an F1C with a 3.7" pulley, and I see 15 psi from about 4500 through redline. My wastegate is set at 15 psi, as soon as it reaches that, the wastegate opens and maintains that 15 psi and bleeds off the rest. I am getting some belt slip up top, but it's still holding my desired boost level, so it can slip all it wants.

Twinscrewgt on here is also running a similar setup on his 2011 GT. His is an F1A and he's got his set to 10 lbs through redline with a 3.85" pulley.

Anyone who knows Prochargers and F1's, knows the 3.7" and 3.85" pulleys will make 30 psi + on these cars. The wastegate allows us to run a lot less boost for pump gas, and builds boost a LOT quicker and lower in the RPM band. It works REALLY well. I've got 5 lbs at 2500 rpm. It's a smooth broad power band. It doesn't spin the tires at 2k like a twin screw, it's not on or off like a turbo, and it's not peaky like a centri. I've had 3 '03 Cobra's, 2 single turbo cars, and a twin turbo 03 Cobra, so I'm very familiar with each of their pros and cons.

If I did have one complaint, it would be that it makes a bit of noise. Otherwise it's a really nice usable setup with great adjustability. I've got some tune issues we're trying to work out (part throttle problems), but once that's done we're going to experiment with different pulley sizes from 3.4" to 4.38" and see how each one effects hp/tq and IAT's all at the same peak boost number (probably 14-15 psi).

FWIW, 542hp and 538tq at 14 lbs. Peak tq at 4800, peak hp at 5500.

 

[bigmachano]

I'm running this setup.

I have an F1C with a 3.7" pulley, and I see 15 psi from about 4500 through redline. My wastegate is set at 15 psi, as soon as it reaches that, the wastegate opens and maintains that 15 psi and bleeds off the rest. I am getting some belt slip up top, but it's still holding my desired boost level, so it can slip all it wants.

Twinscrewgt on here is also running a similar setup on his 2011 GT. His is an F1A and he's got his set to 10 lbs through redline with a 3.85" pulley.

Anyone who knows Prochargers and F1's, knows the 3.7" and 3.85" pulleys will make 30 psi + on these cars. The wastegate allows us to run a lot less boost for pump gas, and builds boost a LOT quicker and lower in the RPM band. It works REALLY well. I've got 5 lbs at 2500 rpm. It's a smooth broad power band. It doesn't spin the tires at 2k like a twin screw, it's not on or off like a turbo, and it's not peaky like a centri.

If I did have one complaint, it would be that it makes a bit of noise. Otherwise it's a really nice usable setup with great adjustability.

FWIW, 542hp and 538tq at 14 lbs. Peak tq at 4800, peak hp at 5500.

there we go, just the answer i was looking for!

and one more tard/newb question: what would be the optimal wastegate placement?

 

[19COBRA93]

sorry just got to see this (computer wouldn't open it up in iraq). that looks pretty interesting. as i understand it, the red race valve from procharger is somewhat adjustable. would i be able to create this same effect with a procharger and the red race? what i was thinking was hooking the bypass up to a tube (pvc or otherwise), monitoring air pressure from an air hose and then adjusting it to open up at 10lbs. does that seem like a dumb idea, or is my logic right?

The Procharger red race valve will only open under vacuum. Under boost it's closed tight. You'll need another valve to try to control boost.

 

[19COBRA93]

and one more tard/newb question: what would be the optimal wastegate placement?

It needs to be a blow through setup with the MAF after the intercooler (or at the outlet of the intercooler like on some of the Prochargers), and then the BOV, and wastegate anywhere between the supercharger and intercooler inlet.

 

[bigmachano]

The Procharger red race valve will only open under vacuum. Under boost it's closed tight. You'll need another valve to try to control boost.

that confused me a little bit and shows me that i need to do A LOT more research before i install my supercharger

It needs to be a blow through setup with the MAF after the intercooler (or at the outlet of the intercooler like on some of the Prochargers), and then the BOV, and wastegate anywhere between the supercharger and intercooler inlet.

so on the "stage 2" system that has the maf built into the intercooler, the wastegate would go between the compressor and the intercooler and vent where? i'm sorry for the 20 million questions, i really should be doing more research and less wasting people's time. i swear, the more i learn the less i know. i spent the whole deployment researching this and now i don't feel that much further than when i started! i can't wait to get some hands on experience and get my ass back in college so i can understand this stuff on a conceptual level!

 

[19COBRA93]

that confused me a little bit and shows me that i need to do A LOT more research before i install my supercharger

The big Red Race valve is just a BOV. It's purpose is to vent pressure when you're off the throttle. On the throttle, boost pressure fills the diaphram (from the top) and holds the valve closed. A wastegate works the opposite way. The spring is much stiffer, and when under vacuum or low boost the valve is closed. Under throttle the diaphram fills with boost pressure (from the bottom) and when the exceeds the spring pressure (desired PSI), the wastegate starts to open and bleeds off pressure.


so on the "stage 2" system that has the maf built into the intercooler, the wastegate would go between the compressor and the intercooler and vent where?

This is how mine is, The wastegate just vents to atmosphere, as does the BOV.

Answered above in bold.

 

[bigmachano]

awesome! i just read a little bit that led me to believe that and then you solidified it. i'm pretty sure that i'm going to throw a wastegate on my system for insurance if nothing else. i mean, i'm going to be running really low boost anyway, but this just seems like the way to go

 

[bigmachano]

and to ammend that, the only reason i could see not to have one would be price... besides those cheapos on ebay

 

[19COBRA93]

and to ammend that, the only reason i could see not to have one would be price... besides those cheapos on ebay

Fitment, and price...And necessity. There's very little room for it, they can be pricey, but the Ebay cheapys actually work well, and most people just don't need it.

 

[bigmachano]

good call, i was worried about them having to be installed in-line, but after some reading, you're help and finally looking at pictures, i think i have a good idea now. i think at low boost, a ebay cheapo is gonna be fine insurance for me. i'm gonna do it, now i just need to figure out what size.

 

[19COBRA93]

good call, i was worried about them having to be installed in-line, but after some reading, you're help and finally looking at pictures, i think i have a good idea now. i think at low boost, a ebay cheapo is gonna be fine insurance for me. i'm gonna do it, now i just need to figure out what size.

For what you're doing, a 38mm will work great.

 

[bigmachano]

you sir are a god, thank you very much

 

[Alter Ego Trip]

you sir are a god, thank you very much

I've heard Cobra called a lot of things, but that there would be a first.

 

[bigmachano]

wild turkey is a hell of a drug

 

[circusboy]

I'd like to get in on this some.

I'm running a 15% o.d. crank pulley, 2.75" blower pulley. I was wondering if i was over spinning my blower. based on my calculation it's 56,900 rpm on the impeller

crank pulley 7.7658

blower pulley 2.75

difference 2.82

highest RPM before boost nose dives 5700

blower multiplier 3.54

5700 RPM x 2.82 = 16,074 rpm in the input

16,074 x 3.54 = 56,901.96 rpm

does anyone know the max impeller speed on a novi 2200?