slots in blower top ...

stephens89sc

Registered User
ok now ive been reading the post about blower whine and i want to know more about these 2 slots bedise the "v" opening,


what will happen if i close them.....?
 
DONT

dont do it i did this and it makes no more hp does make more noise but air temp goes up if you notic magna port still has them its for a reason,, trust the pros like magnuson on this one it does no good to seal them up. and if you weld them up you may warp the blower case, I opened mine back up after one hour of running it it helps the boost get out and removes some of the boost pressure before the vee openning making for better flow.
 
Well I must admit mine are closed and blower whine is definately greater..really cant tell you if my SC outlet temperature has gone up..But I can tell you I was making 21 psi with a 2.95 blower pulley..I recently went to a 3.05..and yah..Cars faster haha..Lilless boost...I went from a stock 94 blower with the Magnum powers inlet to a Ported 94 blower by ESM with my Magnumpowers inlet port matched.....I can tell you the power difference between stock and ported was amazing....Mind you that ESM rebores the supercharger case after doing any welding to it to make sure its true...I have heard that the eaton cases shrink when subjected to extreme heat (welding) This can cause distortion of the case and messed up rotor clearences...So I guess I would talk to the profesionals at ESM or Magnum about this before proceding with welding the V's...Ill tel ya though..even with a fullexhaust on my car...You can here that blower whine thjree blocks away:O)
 
Damon-

Are you saying that SC boost increased to 21psi due to the combo of sealing the slits beside the center vee and the 2.95 inch pulley? I didn't know you could get that much boost from the SC. Is that pulley a 10% overdrive or is it more?
 
the vee

How far can you enlarge the vee? Does making it way larger increase SC flow and boost abilities?

I custom ported my SC inlet and outlet a while ago and made the vee about 3/8 inch bigger on all sides that allowed enlargement. I saw some room to open it up even more. If this was done would this hurt the functionality of the supercharger?

Right now as it stands i can get 16+psi with it using a stock pulley at 4,500 rpm. I am planning to install a 70mm TB to increase flow and boost even more as i still have a stock TB (bored out a little) as this is the last bottleneck on my intake.

Randy-
 
Randy..

There isnt much improvement you can do as far as outlet of SC is concerned..From what I've seen from Magnum and ESM there is minimal work done there..However there is one bolt boss that you can grind away...It can slightly disrupt flow..You would then just cut the end off of get a shorter bolt...Most of the work I seen was not only enlargement of the inlet of the SC but a recontouring of it as well..Keep in mind bigger isnt always better..As far as the V is concerned I had the porting and the pulley all done at the same time...The 21 psi was measured with an Autometer boost gauge..I was suprised I didnt blow anything to be honest..Thats 21psi with an intercooler that flows 700cfm and a full exhuast including headers....Im doing a cam and head swap in the near future and I'll see how much the boost goes down from there..If you do planon filling in the V make sure to do a before and after boost comparison..Just to see if it actually does make a difference...All I can tell you is that my blower whine increased signifigantly with just the ported blower upgrade
 
boost change after vee enlargement

When I ported mine i did see an increase of about 2 psi or so by itself, especially with the raised top. I also did what magnuson did by beveling/rounding the inner edges of the vee by hand to improve outflow. I am pleased with the performance increase and yes my blower is much louder too. Now that i think about it i agree with what you said- bigger is not necessarily better as far as an m90 is concerned.

I think installing the 70mm TB and a double intercooler on mine will allow the maximum benefits of porting the SC to be realized.
 
Ive personally wondered what improvements the double intercooler may actually have. Sure the CFM capability will be over stock but The stock IC barely gets enough air to cool//How much air will be passing through a double thick IC??Perhaps buying a higher flowing core would be the hot ticket. I have the Spearco replacement IC which has been discontinued. Many say its junk but the core according to Spearco flows 700CFM. Still the problem with that is coooling..Does it get enough air?..I run it with a fan but still I think thast teh limiting factor of having an IC in that location.>Airflow over the core.Even if you increase the CFM or surface area....Is it getting enough air to cool it down.:O)

Just my two cents as always
 
The slits are there to let the pressure buildup out of the blower top before it reaches the larger opening.If they were closed it would impede the rotation of the blades as they are allowed to spin much freer when the slits are open because they allow some of the pressure to bleed off which helps the blower spin more easily and because of this it also helps to lower air temps.Also because of this the blower uses less power in the driving of the blower which also increases efficiency.Basically the less material that the blades are opposed to the less the temp as well,up to a point as too much and you will cause the flow to lessen.The easier that the blower flows then the air temperature will lessen as there is more avaliable air to be sucked in the blower.This is what i have found out by talking to many experts in the blower field.
 
purpose of slits

My question would be then is there any significant advantage that can be gained by enlarging the slits slightly and still maintain boost pressure? perhaps an increase of efficiency?
 
Yes i have seen these pics before and they have said that the only major advantages were made in the outlet temps.They show a couple of pics with the slits enlonged but they do not say which pic is the one with the greatest advantage.The Magnum Ported blower has only had the large exit port enlarged thus it should not make a big difference to performance to open the vents any more.I have talked to many people who rebuild and test blowers and they all told me that the slits are just to help the blower exhaust the compressed air so that it will help to keep the impeller speed up and not hold the blower back by somewhat cavitating.The largest advantages are by opening up the entry port ,it is the major restriction.
 
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