problem with the boost

[marauder004]

Hi everybady,

I have a prablem with the boost
my car is marauder 2004 eaton swap.
it has forged block same as cobra 2004 also headers 3.73 gear etc....

I have 3.1 non-slip pllti flow upper 2lb lower but the problem the boost at this pulley shoud be 14 when I saw the members but their number with the boost information.

my car right now for example start at 2500 rpm the boost at 13. Then when I go higher RPM the boost decrease !!!:mad2:

then at 6000 RPM the boost decrease from 13 to 10.5 or some time 10 or some time 10.8 max!!!:confused:

at the higher RPM the car goes to the rich side 10.3 !!!

my question is 3.1 upper and 2lb lower should be 14 psi or 13?

and why the boost is decrease at high RPM??

when I was with stock block and stock upper pulley and 2lb lower the boost was 11 and I don't got this problem at all.


any help will be appreciate :depress:

[loud2004marquis]

I'm no expert, but maybe the heavier rotating assembly?

[SC Cheesehead]

Have you checked all the vacuum lines and intake connections? Sounds like you may have a vacuum leak. What's your boost gauge read at idle?

[Marauderjack]

Belt slipping??:confused:

[RF Overlord]

Belt slipping??^^^ This. ^^^

[MOTOWN]

Check your bypass valve, and connections

[RacerX]

If you look at 03/04 cobra dyno graphs, you will see the same issue. Port the Eaton sc and elbow, or get a larger throttle body with matching elbow. LFP, Accufab, Dragon... You still need the Eaton ported though.

Here's what a ported Eaton will look like:

http://www.mercurymarauder.net/gallery/data/628/medium/DYNO_460.jpg (javascript:;)

[marauder004]

Have you checked all the vacuum lines and intake connections? Sounds like you may have a vacuum leak. What's your boost gauge read at idle?

I checked all today but there are no leak

read at idle 10 vacum
but when I start the engine it stop at 18-19

there are no leak

do you think it's from sliping the belt?

the belt fit exact...!


Check your bypass valve, and connections

I check it today it's OK

[SC Cheesehead]

Have you checked all the vacuum lines and intake connections? Sounds like you may have a vacuum leak. What's your boost gauge read at idle?

I checked all today but there are no leak

read at idle 10 vacum
but when I start the engine it stop at 18-19

there are no leak

do you think it's from sliping the belt?

the belt fit exact...!



Check your bypass valve, and connections

I check it today it's OK


Should be pulling 20 lbs vacuum at idle, sounds like there's a leak somewhere.