This one is weird on me. I went back to my tuner's dyno yesterday, hoping to eliminate a P0175 code that pops up randomly, and to tune for the 8 and 10 lower. Slap the 8 on there, 506-536 HP, 538-572 TQ gain from the 6# lower. Boost jumps from 13PSI - 14PSI

10 LB goes on. Boost stays at 14 LBS peak, HP and TQ maybe go up 2 HP through a pull on a cool engine. Mind you, this is with a new Gates belt, Magnum Bracket and so tight you can play treble chords on the band.

I was thinking bypass valve control, however I think if it was leaking the boost would be sluggish. It's not, on a regular kick-down the boost immedately jumps to 10# and quickly rises to a peak of no more than 15#, even on a cold, dense air night. This is on an fully built 9:1 CR Longblock with stg 2.5 heads, stg 2.5 cams, Dynatech headers, Dynatech midpipes and Bassani Catback. The C/L plenum, SBTB and a Tru-Flow filter are in the airstream.

So what do you guys think? Excessive blower/rotor clearance? My tuner mentioned that some Magnums he's seen had too much clearance, would never boost well and generate excessive heat at higher boost ranges.

 

On my JDM built longblock I see almost 20# boost with a 10# lower. About 23#s with my custom 11" lower. I find it difficult to believe your setup flows that much better than mine, so something is definately wrong.
Jim

 

I don't know why; but, my MP never performed as well as I expected it to. Maybe that's why. Who knows? It's long gone now. Much happier with the Whipple though.

 

"My tuner mentioned that some Magnums he's seen had too much clearance, would never boost well and generate excessive heat at higher boost ranges."

When i put anything over a 6 pounder on my ported eaton it would almost do the same thing. So i stuck with the 6er and put a better heat exchanger and went with the powercooler. If you want any more then that i would go with a a different blower set up. My buddie put the wipple on his 03 cobra and its just insane how much more you get out of the wipple at the same boost levels. BUT for the thousands of dollars your guna spend on a new blower. wich is not in every ones buget. but i think the 538-572 TQ gain from the 6# lower is purdy respectible!!.

 

That is weird MOP ??? One thing I never had a prob with was making Boost on the Mag, I ran mine as high as 25lbs, I had at least 6 pulley combo's, and it clearly responded to each diff set up, (right up to me over boosting what the springs would handle THEN you will actually lose Boost. BTW you wont see big HP increases with pulley changes like you would think, BUT you should see TQ increase.

Boost Acuator could be an issue, it did happen to me once and Sal had to fix me up.

As for Rotor clearance I wont buy that, most of the SC's out there chew the schitt out of the case, (Eatons, Mags, KB's, Whipples, ALL OF THEM in time).
I've seen some really badly chewed up cases run best ET over and over, and on my Mag Jim actually had to have my case (line bored if you will) to get rid of all my chew marks. Even after that catching Hi Boost was NEVER a prob.
AMOF now a days most remove the coating from the Rotors when it gets ported and actually increase the clearance.

Do look over the Acuator, and make sure all the vac lines in that little cluster are right (been there done that too, hehehehe) MAN DOES IT WHINE WHEN IT'S WRONG THOUGH

Good Luck and let me know how you make out

 

Update: Installed my old 12" LFP cotton gauze filter. Stumbled a lot on tip in and part throttle - I think it's really lean at partial throttle settings now. Lean enough to need a new tune!

WOT yielded the same results. I lowered the peak timing to 10* to be safe, in case it was too lean. Jumps to 10, quickly ramps to 14, and almost nicks 15 PSI before the 3-4 shift with the stock upper and 8# lower. I'm going to have to look somewhere else in the pipeline for a root cause to boost flatlining, methinks.

 

Are you using stock valve springs?

LB

 

BINGO !!!! Good call lightning Bob!That was my next question. High boost levels WILL float the springs. A very good possibility. #1 overlooked mod in my book.

 

108# springs with Ti retaining hardware. Came with the stage 2.5 heads. JDM built this motor for some decent boost. I dropped an email to Charles, hopefully he might have some insight as to what could be the issue.

 

With a 6# lower, the 2.7 upper, full exhaust, 14* of timing, and an aggressively lean tune, my truck could only muster 413 rwhp and 500 lb/ft with the MP. (Stock long block) Only 15 more than I was making with the stock Eaton, a 4# lower, a 2.8 upper, full exhaust, and 14* tune that wasn't as lean. Either all MPs are not created equal or they are bunk. The truck responded well to the Whipple thank god. I was starting to think something was wrong with my truck.

 

Where can i get a 10" 1/2 or 11" lower ?
Who made the custom 11" lower for you ?
Thanks.

 

I got mine from LFP for my 02



With that Lower Pulley and this Upper Pulley



My Mag saw OVER 25lbs of Boost

Dont know what pulley combo I have with the Whipple and I truly dont care,
but I can tell you catching 15lbs is a cake walk,
I can do that at 1/8 - 1/4 throttle pulling away from a light and thats with that big *** Upper on it,
(I change uppers at the track and add more)

BOOST IS DA SCHITT and totally needed if you want a Mag to give you noticable increase
over an Eaton. MOP I truly hope you figure it out : o (

 

Here is a 11in pulley





Here is a 10lb vs 13lb

 

MP guys brag about their "inches" of lower pulley, while Whipple and KB owners brag about the power

 

The (foam) Truflow filter is a big restriction, it has been admitted they do not flow as well as Gauze or Dryflow AEM filters (which I run), I had 3 different foam Trueflow filters and none of them flowed as well as a normal K&N, S&B, or the Dryflo AEM filters. BUT the Trueflow filters the most fine particles.....it's fine for most people, but is hurting you with your aspirations of high boost