Hi;

I'm looking at doing some F/I work early next year. My question is how much boost can the vortech V1SQ unit effectively produce. I know that RMS got 13 psi on one of their kits. I will be lowering my CR to around 9:1 and putting in forged pistons and rods.

T.

Its not about what the blower can produce. If you go to the vortech site, youll see that the blower can handle about 21 psi. But on our cars, its limited to about 14-15 psi at the absolute most. The numbers on the site tell you that the blower is capable of about 50,000 rpms.

With my 6" crank pulley and 3.125" SC pulley, Im making 10.5-11 psi boost. But if you plug the numbers in on the site, youll see that my pulley combo, at 7000 rpms, spins the impellor at about 47000 rpms. I only have about 3000 more rpms to spin before Ive hit the spec limit, and that will be not much higher than Im doing now with my 11 psi. So thats the real limiter. Its the rpm spec of the unit's impellor.

So how is RMS getting 13 without going above the 50,000 rpm limit?

Is 9:1 a good CR to aim for or should I go lower/higher? My goal is to run around 15 psi

Thanks,

T.

>>So how is RMS getting 13 without going above the 50,000 rpm limit? <<

Just go to the site and plug in the numbers. Id imagine that 13-14 psi is prettynear the max rpm allowed. That doesnt mean theyre exceeding it..

I'm running RMS's 6" crank pully with a 3.12 S/C pulley, and I'm only running 9-9.5 psi @ redline.....

I've been thinking about upping my boost, but the next size pulley (6-ribbed) would be a 2.87 which puts the impeller speed of the V2-SC at 51177.7... over the 50K limit...

Vortech does sell a 8-ribbed... 2.97... which I guess would work with the 6 ribbed crank pully... which would put me just under the 50K impeller speed limit @ 49454.55....

Would a 6" crank pulley/2.97 supercharger pully put me @ 10.5-11psi?

-Dave

>>I'm running RMS's 6" crank pully with a 3.12 S/C pulley, and I'm only running 9-9.5 psi @ redline<<

DAve, how much do you think the Aftercooler is taking? Actually, its not much. The typical stage II rms M3 kit will make about 8.5 psi. Thats done with the 6" crank pulley, and the 3.33" sc pulley. Stepping down to the 3.25" sc pulley brings the boost to about 9.5-10 psi. And using the 3.125" pulley brings it to about 11-12 psi. Pushing the air through the heat exchanger is bound to take some psi, but probably in the 1/2 psi range.

>>but the next size pulley (6-ribbed) would be a 2.87 which puts the impeller speed of the V2-SC at 51177.7... over the 50K limit...<<

Its also a good candidate for belt slippage!! Going smaller than 3.125 you should probably consider going to the 8 rib setup. Im not saying Every 2.87 6 rib pulley/belt would slip, but it increases the odds certainly.

>>Vortech does sell a 8-ribbed... 2.97... which I guess would work with the 6 ribbed crank pully<<

I would rather you changed out both pulleys and tensioner to the 8 rib setup. If you change one component, I think you should change all. You dont want ribs overhanging the edge of the pulley.

>>Would a 6" crank pulley/2.97 supercharger pully put me @ 10.5-11psi<<

I think we need to determine first why the 6" / 3.125" combo is only making you 9 psi! Are you redlining at 7000 rpms? If so, than something is amiss I think.

redlining @ 6800.....

I've never actually tested to see my boost is @ redline (don't have a boost guage installed)... outside of the RMS install... Osh told me I was @ ~9.5 psi at redline.....

RMS states only a 0.3 PSI pressure drop at 10 PSI of boost with their aftercoolers....

>>Osh told me I was @ ~9.5 psi at redline<<

Well, Marco on his stage II Plus M3 also has the 3.25" pulley, and hes making near 10.5 psi boost. I know HIs numbers are accurate because it comes from a well callibrated Dynopack system which reports on boost as well as other things. A 1 psi difference is not all that much, but realize that if things are all running properly you can count on a single psi to be responsible for around 15 hp. So if I were you Id get a boost gauge of your own, and check your boost as you drive. Without one, for instance, youll never know if your belt is slipping right on top, where you make the biggest boost increase over a very short distance near redline. Its impossible to make good boost calculations and plans without measuring it regularly.

>>RMS states only a 0.3 PSI pressure drop at 10 PSI of boost with their aftercoolers<<

Right. I believe this. Thats why the pulley combo I use produces 11 psi on mine, and 10.5 on versions with the aftercooler. It Doesnt account, though for your 9-9.5 psi. Get a gauge, and check for leaks, belt slippage, etc.

Wait......Do you have a Z3, or an MZ3? Might that not cause the difference? The psi numbers Ive been referring to are on M3s.

Also, because of the shape of the boost curve, I wouldtn be surprised if at 6800, you werent making over a half psi less than at 7000.

The RMS Stage 2 for the z3 2.8 is rated at 10.5 psi

http://www.racemarque.com/rms_bmw/modules.php?name=Content&pa=showpage&pid=59

With the aftercooler deducting about 0.3-0.5, you should be around 10 psi

I'm guessing that the Stage 3 setup is at 12 psi on the M 3.2L (S52) and that the M coupe's 13 psi is a type-o.

Anyone know how much the V-4 Vortech units cost? They go up to 65,000 rpm impeller speed and up to 32 psi of boost :)

T.

>>The RMS Stage 2 for the z3 2.8 is rated at 10.5 psi<<

I know this is what his page currently says, however I promise you, there are many units theyve shipped and configured over the years that do NOT match these specs. For years, their stage II kits came making 8.5 psi, and also advertising the same 411 hp. No wonder people get confused.... When Marco got his kit, it had the 3.33" pulley, and was making that 8.5 psi. My only point is that DakarDave needs to get a boost gauge and monitor his boost himself at wot at redline in order see why hes not making more boost than 9 with a 6" crank pulley and a 3.125" SC pulley combo, because that combo should be good for near 11 psi.

My experience with Vortech and boost says
3.60 pulley 6.0-6.5 boost
3.33 pulley 8.5-8.8 boost
3.25 pulley 9.5-9.8 boost
all with 6 inch crank pulley, all with aftercooler.

I added headers and went from 9.8-10.3 lb boost

Also you should not run your blower over 90% of the 50,000 RPM MAXIMUM.
That would mean the most efficiency happens @ 45,000 RPM and UNDER.
I have been told by Vortech that over 45,000 , the blower will prematurely wear out and be less efficient. I run mine at 44,900,if my memory is correct.

All my boost measurements were done on the Dynopack with its measuring equiptment. MARCO

Yes, I've seen that their new site states 10.5 psi of boost for their stage II cars....

Osh told me that I was running ~9.5 psi and I don't have any reason to doubt him... but I guess verifying it would hurt....

<<My only point is that DakarDave needs to get a boost gauge and monitor his boost himself at wot at redline >>

I agree I do need a boost/vac gauge...

If I am running 10-11 psi, then I'm not seeing it reflected on the dyno... I dyno-ed the car ~ 2 weeks and 500+ miles after the install, and I saw 265rwhp @ just under 6500 RPM... for some reason the operator didn't pull to the new 6800 redline..... I assume I would have peaked at about 280rwp if pulled to 6800....

I would expect 10-11psi to net me around 300rwhp....

-Dave

Also if Math holds true, the 3.12 pulley should yield 1.5 lb of additional boost or about
11.2-11.3 lb boost. But on my car it would be about 12 lb boost with my headers.
Not sure I am going to go there, but I know I will make 400 RWHP if I do. Marco

Hey guys... I'm being overly anal in this regard... but people have a somewhat skewed understanding of "PSI" (pressure). You COULD make (theoretical) 20psi on your car if you choose the max RPM of the compressor to be at a very low engine VE point (and low RPM) so that the engines demand for air isn't as great... thus the amount of flow (volume of air being moved) by the compressor is THAT much greater than "consumption."

Also, one more thing while I'm at it... Paul was saying he's making about 11psi @ 47,000rpm impeller speed... but what most people forget to compute is that in a centrifugal application the difference between impeller speed and volume is an exponential relationship.

Clear as mud? :)

Boris

doesn't the psi depend on what the engine can process. I have FI cams in my car and a 3.25 pulley and I get in the range of 11-12psi and sometimes more under a load. Why would this be???

is there room to fit a larger diameter crank pulley? that would be a better way to go. less slippage without the need for an 8 rib.

PSI is a measure of back pressure.

I can get 50 psi if I hook a s-trim to a lawn mower. I couldn't make more than 9psi with it on my stroked and built mustang.

Originally posted by JazzM
Hi;

I'm looking at doing some F/I work early next year. My question is how much boost can the vortech V1SQ unit effectively produce. I know that RMS got 13 psi on one of their kits. I will be lowering my CR to around 9:1 and putting in forged pistons and rods.

T.


Vortech makes different blowers for different applications.......
along with differnt size pulleys....


Why not give The authority a call 1st...and ask your specific questions directly to them..............

Vortechengineering.com

Fast4d.. I have a question about your theory (i'm not saying its right or wrong, just a question...) if i understand you correctly, your saying that a motor with more restriction will produce a higher PSI. Well, if thats true, than why is it that when Marco added his headers, he had an increase in his PSI? Does this mean that his new headers are more restrictive than his old ones?

BTW, thanks for all that are participating... there is some good information in this thread.

what did he use for reference? boost gauge?

most boost gauges are not accurate down to the tenths. except maybe those expensive ones from HKS. it would be difficult to read while the car is moving anyway.

if he gained .5 lb of boost there could be a number of things.

weather changes

removing the restriction in the exhaust = less pumping loss in the engine allowing the engine/blower to accelerate faster

Doesn't removing a restriction in the exhaust= less back pressure though which means less psi?

Do any of the larger vortech s/c units have the same mounting points as the V2sq? This would allow an upgrade without having to go to a custom mounting bracket.

When my boost increased from 9.8 to 10.3 by the addition of headers only, it was in September 2003, 2 weeks apart,had one dyno, installed headers and dynoed again immediately, pretty much the same temp outside and the boost was measured on the Dynapack hooked up to a vacuum source.

I personally have NEVER depended on my gauge for boost quoting, because I do not feel the gauage is THAT accurate.

The Dynopack gave me my boost numbers, not my gauge.
Marco
One thing I will add though, at the time I installed the headers, I had 2 custom pipes installed right to the cats. They are 2.25 pipes.
The stock pipes were reduced at different sections of those front pipes, the new ones are wide open and do not have the "pipe in the pipe" anymore in the front pipes.

Originally posted by Spencer
Do any of the larger vortech s/c units have the same mounting points as the V2sq? This would allow an upgrade without having to go to a custom mounting bracket.



YS trim

good for 1000hp!

I had 1 of those bad boy it's friggen huge!

Originally posted by fast4d
YS trim

good for 1000hp!

I had 1 of those bad boy it's friggen huge!

Thanks for the info.

Checked their site...... $2600 for the unit alone.

:eek: :eek: :eek: :eek: :eek: :eek: :eek: :eek:

Originally posted by Spencer
Thanks for the info.

Checked their site...... $2600 for the unit alone.

:eek: :eek: :eek: :eek: :eek: :eek: :eek: :eek:


that's BS. think of it as MSRP.

I bought the whole YS kit for my stang for $2500 (includes brackets, pulleys, belts, BOV, tubing).

you should be able to get the head unit for $2k or less.

I don't think it'll fit BMWs the volute is WAY big. you guys might be able to fit a T trim in there though.

here was mine out of the box.

http://www.akkm.com/ys-trim.JPG
http://www.akkm.com/ys-trim2.JPG


btw, the domestic crowd spin these things above spec max rpm all the time and they never break.

sure it looses a little efficiency (hotter air) but the power goes up.

but then they are not at 10.5 CR

What's the ideal CR for running around 14-15 psi boost on street gas?