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The Ubiquitous Jimmy V.
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Discussion Starter · #1 ·
.BOOST :jawdrop

You can stop belt slippage via BilletFlow pulley.
But after you get past 14lbs boost,what else can you do to stop boost from dropping back??
I hear claims of guys making 15+ lbs and there boost not dropping off.
CLAIMS
You can hold 15,16,17 lbs whatever to about 5000 even 5500 rpm's but after that they all loose boost.
Under load while running car in 4th gear you can hold boost but after 5500rpms i see them all fall off.
On dyno boost starts dropping after 5000 rpms on every car i have seen.
Share the secrets if there is something else i am missing..

BOOST :jawdrop
jim v.
 

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two words jimmy...... heat soak.... these blowers are not supposed to turn this fast
 

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Bingo, I think the bump valve mod helps, ? the blower gets verry hot,

Hey Jim another reason for the kb blower , 16 lbs cool air charge,
80hp more than the stock unit at the same boost, I tested it at 16 1st then 18 then 25, I couldnt wait to do them all, at 16 the kb felt the same as the eaton at 22lbs, NO Ice
Heat ! :cool:
Little secret, When I ice the blower also ,it picks up a bunch. On the dyno that is. peace
 

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Something else I did was use a differential pressure calibrator I have and fine tune the actuator stop on the controller. I had a bunch of bleed by after 5000 rpm. This seemed to really help and I gained close to 1 lb more of boost. I just think the factory didn't adjust it real close and not very consistent either. You can also do another trick we did on the lightnings. The actuator closes when you come into boost. I tune it to close at 5 in. vacumn. This brings boost on much sooner and with a timing adjustment at tip in really gives the car killer throttle response.

Rick
 

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AmazonRacing said:
Something else I did was use a differential pressure calibrator I have and fine tune the actuator stop on the controller. I had a bunch of bleed by after 5000 rpm. This seemed to really help and I gained close to 1 lb more of boost. I just think the factory didn't adjust it real close and not very consistent either. You can also do another trick we did on the lightnings. The actuator closes when you come into boost. I tune it to close at 5 in. vacumn. This brings boost on much sooner and with a timing adjustment at tip in really gives the car killer throttle response.

Rick
Hey Rick,

Can you post some info on how you fine-tune the actuator?

Thanks,

MJ
 

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What exactly is the bump valve mod?
 

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The Ubiquitous Jimmy V.
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Discussion Starter · #10 ·
Hot Rod Harry said:
LOL...no...Pete ads a stiffer spring to keep it from opening.
:D Now Pete has a Stiffer Blower

jim v.
 

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Hey Harry,

Does the Dump Valve not open at all?? If it doesn't, won't that waste a lot of gas at light throttle driving when you don't really want/need boost(but are "forcing" the SC to make boost)?
 

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The Ubiquitous Jimmy V.
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Discussion Starter · #12 ·
larryc7777 said:
Hey Harry,

Does the Dump Valve not open at all?? If it doesn't, won't that waste a lot of gas at light throttle driving when you don't really want/need boost(but are "forcing" the SC to make boost)?
hmmmmmmmmmm!
Good Point,,never thought of that.

jim v.
 
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I wouldnt think there would be too much boost build up at cruising or normal driving to have anything to dump. Watch your boost guage...how often do you see it move when you are taking it easy or cruising. None on my car. Its only when you are getting on it alittle or big time.

Harry Mager
www.HotRodHarrys.com
 

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When the dump valve is able to function(even after doing the boost bypass mod), the vacuum motor/controller holds the valve open when vacuum is present and allows the valve to close(spring pressure) when vacuum is not present. The standard boost bypass mod mearly takes the control of the valve away from the computer by making it strickly engine/vacuum oriented. It also uses boost pressure to force the valve closed.

My understanding of how a blower works is like this: As engine rpm causes increased blower speed, boost is produced. The bypass valve is there to "lessen" the strain on the engine by bleeding off light-throttle boost which isn't wanted/needed. This allows the blower to, more or less, "freewheel" & not consume as much HP while spinning. If the modified vacuum motor, that is on your car, is able to move at all under vacuum conditions, then you are good to go....boost will just come in sooner & with less throttle application. BUT, if the engine vacuum can't overcome the additional spring, then the valve will never open. That means that you will be under boost conditions whenever engine RPM causes the SC to spin fast enough to make boost. Great for throttle response but, since boost consumes HP, gas mileage suffers.
Since Pete designed the mod(I think), he probably took into account what I mentioned above & allowed some valve movement to remain.
 

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Hey guys;

What is the diference to this mod and the boost by pass mod? Is this a total different mod for a different purpose? This one is new to me, so please? Input need input? LOL
 

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The Ubiquitous Jimmy V.
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Discussion Starter · #17 ·
You can use boost by pass mod, 2 idler pulleys but if you got more then 14 lbs boost?
Your boost will drop off after 5000rpms.
I made this post for those of you that expect miracles from the Larger Idler pulleys..
You can stop belt slip but you can't stop boost from falling off.
Belt slippage is not the only thing that causes boost drop..


jim v.
 

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Jim,

Thanks for the post. I have had similar concerns and this post was very helpful.
 

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maby thats y I hold 22lbs NO slip! maby 1 lb @ 6000, I can handle that .
Hot Rod Harry said:
I have it on my car....here is a pic of what Pete does to it.
Harry Mager
www.HotRodHarrys.com
;)
 
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