Ques for those with Magna ported blowers

mcate

Registered User
I'm getting ready to put my newly ported blower on, & I'm wondering what pulley to use. I was using a 5% prior to the porting, but I want to make sure I'm not overdriving it too much now. I also will be putting my new double intercooler on. Heads are STOCK, but I ported my exhaust manifolds out to 2". My exhaust has been modded, 2 1/2"-3"-2 1/2" with straight thru cats & Magnaflow resonator/mufflers. What does everybody think, stock pulley or 5%?

Thanx,
Mike
 
David Neibert said:
Start with the 5% and if it makes too much boost, then go larger.

David

Well, the only way I know to define "too much" boost is blown head gaskets. I was kinda hoping of avoiding that!
 
With a MP inlet plenum and my self ported blower (stock outlet) with a a BTM 5% I made 18psi and i blew my headgaskets about 5,000 miles later. The HG's had about 10,000 miles total. They were stock replacements though, not felpro.
 
Well, the safe side of me says to use the stock pulley, then go from there. The car is a 95 with only 38,000 miles on it. As far as I know, the HG's have never been chenged.
 
put a 5% on it at least.

I was under the impression you need to spin a MPII blower faster to keep the same boost level.
 
Not True!!!!!

Boost is a measurement of the BACKPRESSURE that the air is pushing against therefore having pressure.

THe Magnaport or Magnaport II blowers require the same turns to create the same boost. THe double IC will help with lowering boost pressures since it cools the air off.

Anyway, go with a stock pulley from the 95 or go with a 89-93 pulley. Going 5% or larger presents a lot of pressure on the gaskets, lower end, Etc.

Those of us on a mission of HIGH HORSEPOWER will say, go big, the rest, say stock. The Magnaport blower is a GREAT UPGRADE!!!!

Amazing how much power is gained!!!!! :D



Good Luck.



Don
 
Also....

Also, remember that the Magnaport blower makes more power by saving crankshaft horsepower that is saved by not having to turn the blower. THe blower draws air in easier and therefore, saves horsepower.


Less power to turn blower......more power to the wheels!!!! :D



Don
 
lube70 said:
Boost is a measurement of the BACKPRESSURE that the air is pushing against therefore having pressure.

oh.

I was under the impression the sealed time for air was much less for these to almost the limit of not creating a trapped volume, thus requiring slighlty higher speeds to comphensate. And then they can be spun faster yet to make more boost taking advantage of the larger openings.

So a stock 95blower with a 95 pulley will make less boost then a MP with a stock 95 pulley? Hmm, I might by it. If that is true it would appear you could do some additional porting beyond the MP work.
 
lube70 said:
Also, remember that the Magnaport blower makes more power by saving crankshaft horsepower that is saved by not having to turn the blower. THe blower draws air in easier and therefore, saves horsepower.


Less power to turn blower......more power to the wheels!!!! :D



Don

Excellent, & thanx. I wasn't sure, but thought I remembered Bill at SCP telling me to run the stock pulley 1st, & then overdrive it only if needed. I plan on porting the heads as part of next winter's round of mods. I'll probably invest in headers at that time as well. That'd probably be a good time to put the 5% back on.
 
You shouldn't be getting 18 pounds of boost with just 5 or 10% overdrive unless there is a pretty big restriction in your exhaust. You should try to keep the boost under 15 pounds with a stock cam and heads.

David
 
A lot of misconceptions out there regarding boost and headgaskets.

High boost on a motor with stock heads and cam is less stressful on the motor than high boost on a motor with ported heads and cam. The problem with high boost is the high temperatures associated with them regardless of engine mods. If you have a big enough IC you can run as much boost as you want (more or less). Until you surpass 400ftlbs torque you really haven't generated enough pressure to be dangerous to a stock type headgasket. Since no internally stock SC is going to surpass 400ftlbs, it is pretty safe to say that boost pressure isn't going to kill the headgaskets in a stock SC.

What kills the headgaskets in a stock SC is detonation. In stock form and being 10-15 years old, any SC runs a big chance of being badly out of tune. Adding mods to it generally makes that condition much worse and often without and knowledge of the owner. Then add high temps from high boost through an inadequate IC and you have a recipe for guaranteed blown headgaskets.

Anyone who has upgraded their supercharger but not replaced their headgaskets can be pretty much assured they will be doing so shortly. Almost all SC headgaskets are faulty. Not all are leaking, but all OE gaskets are damaged in one way or another. The notion that you can do "this" or "that" to extend their life is a silly notion. If you have replaced your gaskets and are still having troubles, then you have tuning issues and/or cooling problems that need to be addressed. It's really that simple.

Stock replacement Felpro gaskets are sufficient for over 400ftlbs torque and 400rwhp AND 18-19psi boost if the car is tuned properly. It's not magic.

That being said it is highly advisable that with a stock IC you keep boost levels under 15psi.

David
 
XR7 Dave said:
A lot of misconceptions out there regarding boost and headgaskets.

High boost on a motor with stock heads and cam is less stressful on the motor than high boost on a motor with ported heads and cam. The problem with high boost is the high temperatures associated with them regardless of engine mods. If you have a big enough IC you can run as much boost as you want (more or less). Until you surpass 400ftlbs torque you really haven't generated enough pressure to be dangerous to a stock type headgasket. Since no internally stock SC is going to surpass 400ftlbs, it is pretty safe to say that boost pressure isn't going to kill the headgaskets in a stock SC.

What kills the headgaskets in a stock SC is detonation. In stock form and being 10-15 years old, any SC runs a big chance of being badly out of tune. Adding mods to it generally makes that condition much worse and often without and knowledge of the owner. Then add high temps from high boost through an inadequate IC and you have a recipe for guaranteed blown headgaskets.

Anyone who has upgraded their supercharger but not replaced their headgaskets can be pretty much assured they will be doing so shortly. Almost all SC headgaskets are faulty. Not all are leaking, but all OE gaskets are damaged in one way or another. The notion that you can do "this" or "that" to extend their life is a silly notion. If you have replaced your gaskets and are still having troubles, then you have tuning issues and/or cooling problems that need to be addressed. It's really that simple.

Stock replacement Felpro gaskets are sufficient for over 400ftlbs torque and 400rwhp AND 18-19psi boost if the car is tuned properly. It's not magic.

That being said it is highly advisable that with a stock IC you keep boost levels under 15psi.

David

Well, I'm upgrading to a double IC at the same time I put the upgraded blower on. I'll use the stock 95 pulley at first when I get it dyno'd & see where to go from there.
 
If you melt a piston or two from detonation like a friend of mine did, then you can rebuild the motor and install the mls headgaskets, total seal rings and a bunch of other stuff listed on my member's page.

But really, as long as you use your head listen like you said you will be fine. An egt gauge would be helpful too, I am already glad Dalkie talked me into getting one.

If you get one, then screw it, put a 5% on there have some fun and watch the temps. Above 14500 degrees get your foot out of it and you are fine.
^^most of that comes from dalkie so listen to him, I'm just a punk kid anyway.
 
EGT---Exhaust Gas Temperature...

Measures the temperature of the exhaust gases from the engine. Since you can tell how a motor is running by many things including but not limited to the exhaust gas temps, you can properly see how the motor is running.

Also, listening for audible spark knock is not enough. Since by the time you hear it, it's already too late.

Dave (XR7 Dave) is right. The only true way to get these cars to perform correctly with mods is to tune them. Same as re-jetting a carb or changing the springs in a distributor would do.

This is the CORRECT way of getting the most from these cars at a safe rate.


Again, you're at the right spot. MUCHO KNOWLEDGE is here. Join the club if you have not done so to gain access to the members boards and the knowledge is boundless!!!!!



Don
 
Jake,
The egt will basically tell you if you are running dangerously lean or detonanting to an extent. I would imagine it could detonate a small amount (briefly) before you could see it on the gauge.

Basically if you egt is low then your butt is safe. If it getting dangerously hot (melt a piston) you can see it coming with the gauge.
It is a great gauge, but fairly expensive and an absolute PIA to install. Plan on a day if you remove the manifold to drill it. The thermocouple needs to mounted 1-2" from the head. There are pics of the egt install here in the preformance section.

Dalkie talked me into this when I was grilling him about a $200 fuel presure gauge. Those look nice and are easy to install, but don't tell you a whole lot. If you see the pressure drop then ya, your in trouble. But a wideband would do a much better job of that as far as AF ratio goes.

I think with an egt and a wideband we should be able to sleep at night. I still need a wideband but don't know which one to get. Hey, I am going to a dyno wednesday, but it is stang dyno so the numbers are going to be low :rolleyes: I wish there was a dyno jet around.
 
Thanks Julian that's what I needed to know. Looks like it takes a while to install so I probably won't do it till I put in the new heads. Good luck with your dyno wednesday and e-mail me with the numbers if you don't mind. Jake35thbird@aol.com
 
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