BlackNiteWS6

iTrader: (2)

Before asked, yes i used the search button. Has anyone ever tried to use
something that can adjust or maintain the boost on a supercharger? I know they
use them on turbos. This is how i would want it to work. I would want to put a slightly smaller blower pulley to make the boost kick in sooner and after i hit the boost that i want i would want the boost controller to bleed off extra boost.
Can something like this be done or is it already being done? It seems like a easy thing to do, but most of the boost controllers i see seem to control a wastegate. I like that E-Boost controller that can fit in a gauge pod on the A pillar. If anyone is doing this please post up what model you used and how it works.
Thanks.

Den

Roadie

good concept. I'd love to see a dyno chart with the difference under the curve pulley'd at 12psi versus pullied to max impeller speed and controlled to 12psi. The midrange potential is definitely there for sure.

https://ls1tech.com/forums/forced-induction/979806-any-superchargers-w-boost-controllers.html

chuntington101

you dont need an electric BOV. a guy rigged a Weastgate with an electronic boost controler onto his SC'ed C6 (i think). he said it worked great. he had about 12psi for normal DDing and 16-18 when he really wanted it. he also said it came on just as hard low down on the low boost setting as the high, the boost just table topped out.

Cheers

Chris.

No Juice

iTrader: (11)

Thats a good article but they should have compared the power curves for the blower pullied for 15psi -vs- pullied for 20psi but gated for 15.

That would have shown the advantages on the street as stated by Roadie

Avengeance

iTrader: (4)

This has been covered before.... there are some good discussions on this too. It is possible.

Im not sure what key words to use for the search to find them but there are a few good threads out there on it, a couple are fairly recent too.

BlackNiteWS6

iTrader: (2)

Thats good that its been done and that it works. I like the idea of using the right pullies
to make boost come in sooner then have that wastegate idea or some systems to bleed of boost when you hit the desired boost level. You get the best of both worlds. I wonder how the wastegate or BOV or whatever sounds when it's bleeding off boost pressure...it might sound like **** if it hisses like a tire leaking air..lol.

engineermike

The problem is that 15 psi with a valve bleeding off pressure will make less hp than 15 psi with no valve. You're using up hp to spin the blower, then just letting the extra air go to atmosphere. The parasitic losses are higher.

Furthermore, if you manage to get a serpentine pulley setup to get 16-18 psi from a centri, then you've accomplished something than many people can't seem to attain. I, for one, couldn't get my T-trim over 14 psi with a serpentine setup and all the tricks. So, if you manage to make 16+ from a centri, then count yourself lucky and enjoy the boost! No need to bleed it off if the engine is built and tuned right!

427

iTrader: (3)

Bleeding boost would eat more power and be hard on the head unit. It would be interesting to run an electronic throttlebody in front of the blower inlet and choke it down to control boost, this would take less power to drive the blower and still control boost.

Kurt

chuntington101

this has all been talked about before. as i and others ahve said, the waestgate has been tried and tested...

hate to be a ****, and i seriously respect both engineermike and 427 for what they have done in the past...

Chris.

BlackNiteWS6

iTrader: (2)

^^Who makes the wastegates? Are you talking about a manual turbo style wastegate or some other type?

BlackNiteWS6

iTrader: (2)

I found a post that was started in 2006 about this idea...and it looks like its just best too
leave the D1SC just do it's thing...but i like the idea of upgrading to the Race Bypass that Procharger sells. I'll ge one from Bob at EPP. Thanks all.

engineermike

I've fiddled with this recently on industrial air compressors. I have some high speed centrifugal compressors flowing 48 lb/min at 30 psi discharge. The interesting thing is that you can reduce discharge pressure by throttling the suction, but the discharge air temp stays the same. So, at 30 psig discharge, the temp is 350 deg F (what you would expect), but when throttled down to 10 psi discharge, the temp remains at 350 deg F. This is because the pressure ratio (about 3/1) remains the same regardless of how much the suction is throttled. It's counter-intuitive, I know. The hp required to drive the compressor reduces due to reduced flow rate, but not as much as it would if you slowed it down and reduced the pressure ratio too. Hp to drive the compressor is a function of mass flow rate and pressure ratio. Now. . . if you slow down the compressor to run 10 psi discharge without throttling, the temp drops down to about 225 deg F and the hp drops even more.

Basically, there is no efficient way to reduce high rpm boost without slowing down the compressor or varying some compressor geometry (Variable IGV or EGV's). If you really want the best of both worlds, then install a good efficient screw-charger.

Robert@G-Force

I have discussed this with Procharger and they don't recommend it they say it is hard on the head unit which is still producing the higher boost levels.

ls1290

iTrader: (20)

I know lots of people have talked about doing this, but I have yet to hear any success stories.

massls1guy

iTrader: (9)

A little embarrassed here... never owned a mustang but I read Muscle Mustangs and Fast Fords (MMFF). Good magazine. Let the flaming begin.

Anyway they had an article not too long ago where a guy did what you're talking about. He did it to be able to limit boost to run pump gas on the street and then go all out at the track with race gas.

http://www.musclemustangfastfords.co...all/index.html

427

iTrader: (3)

I never did any real testing, just a little playing in the engine dyno cell. The bleeding of boost after the supercharger caused the belt to slip but did produce the early boost desired. After talking with the SC producer about what I was doing they said stop it before they have a heart attack!! The additional loads from adding all the air volume would cause the sc to fail if driven in this mode to often.
I then did some testing with fixed restrictions on the SC inlet, this reduced the load to drive the supercharger, still added the early boost, but the smaller ones made some nasty air noise that would drive you nuts! My next thought was an electronic throttleblade that I thought could be made big, maybe 120MM, but with a 70 or 80MM hole in it once the top side restriction was determined. Before I went after this we found a transmission that would overdrive the supercharger 1.36-1 at low speeds, then downshift once the engine speed came up. Driving these units on the street gave the desired result, boost would climb quickly getting the car moving, then drop on the downshift to keep the topside boost/SC RPM safe. The unit was deemed to expensive for what the market could accept to cure the problem, so testing died out.
I am currently working on an F-car with the 8 rib/F series Procharger, so the inlet restriction may get revisited for a pump gas solution without changing pulleys.

Nice to hear what works for others!


Kurt

chuntington101

there was a trasmition company (cant rember their dam name now!) that made a small CVT transmition and attached it to a IHI comp. housing. two of them made over 1000bhp on one of the old 3.8ltr BMW M5's i think.

im guessing they would be similar in size tothe rotex stuff but with the CVT transmition....

Chris.

NLR

why would it be hard on the head unit. The head unit has no idea whats going on on the discharge side. It doesnt know or care about the difference. Your not overspinning it so I dont understand why it would hurt the unit. I spoke to a race tech at procharger and they said nothing of the sort to me. " The unit doesnt know the difference " " Its speed is determined by pulley and rpm "

Roadie

I have a few problems with this...

If the belt slips with bleeding pressure off the intake piping, it is going to slip trying to run at full boost. It's time to fix the belt slip -- that isn't a problem induced by adding a wastegate.

The second part also has me scratching my head. If the supercharger is pullied so you keep the impeller speed under the max impeller speed, what's the problem? Why stop it, and why a heart attack? Sure you lose some efficiency (the power it takes to spin the blower harder), but max impeller speed is still max impeller speed. The wastegate opening is similar to having much better flowing heads. The head unit flows the same amount of air, but there's less boost pressure because boost is a measure of air restriction.

I definitely see the point of losing efficiency and taking more power to spin the blower, but efficiency aside, does it make the desired results? I'm reserving judgement until after I see a dyno chart comparing "pullied to x PSI" vs. "pullied to max impeller speed + wastegate bled to x PSI" on the same car. I don't have a blower... Anyone want to try this and post up a comparison dyno chart?

I completely understand what Mike says about restricting the blower intake and air temps. To me, that poses other problems and I wouldn't even consider it as an option.

427

iTrader: (3)

The trans was probably the same one we used, it was made by a company called Antonov (spelling?). The trans was shifted by a combination of load and centrifical weights, but sadly the volume was to low to make the price right. They actually use the trans as a drive transmission in some kind of car in Europe, they said 1.1 litre engine!

Kurt