Low Boost number with paxton. any ideas?

[Mustang dog]

07 GT manual.
4.75l Stroker, Forged internals, balanced ,9:1, Ported stage 3 heads, with stage 3 blower cams.
Stock intake manifold, Stock TB, Paxton 2200sl, 3:33 pulley with CX racing intercooler HPx MAF, Tial BOV.
60lb injectors, S&H 477 Drop in, 12ga direct wire, big line kit at intake. Lots of fuel at WOT 12.4 AFR. 6400 rpm redline.

Tuned on 91 ( no ethanol)
436whp on a mustang dyno, max BO0ST 8LBS, At 4200ft

I am wondering if there is an intercooler restriction ( 12"x24"x3") or should I pulley down? Max RPM currently on Paxton is 46k rpm. Paxton says good for 52K.

I was hoping for somewhere around 12psi, and 550whp. Which I don't think is excessive as the engine is more than capable of more boost. If you add the correction factor for the Mustang Dyno( I'm guessing) on 12% that's somewhere around 485whp on a Dyno jet.

Any input is allways appreciated.
thanks

 

[01yellerCobra]

The ported heads and cams lower restriction which will lower the boost number. You can always pulley down to hit the boost level you're aiming for.

 

[AndrewNagle]

The ported heads and cams lower restriction which will lower the boost number. You can always pulley down to hit the boost level you're aiming for.

agreed Try the 3.125 pulley

 

[Mustang dog]

thank you !

 

[Mustang dog]

I’ve attached my dyno run. Any feedback ?

 

[RocketcarX]

Sounds like you could be playing it safe with timing, I would expect all of those extras to out do a bone stock 4.6 with a Paxton numbers. I agree with pulleying up too

 

[stkjock]

dont get hung up on boost #s, boost pressure is a sign of restriction to the engine, the HP numbers are what the focus should be on

my old 4.6 made 435 @ 10# w/ 93 oct on a MD w/ a Vortech


I think your fuel is holding you back some, I'd go down in pulley size and ask your tuner about timing used at WOT

can you run 93?

 

[Mustang dog]

dont get hung up on boost #s, boost pressure is a sign of restriction to the engine, the HP numbers are what the focus should be on

my old 4.6 made 435 @ 10# w/ 93 oct on a MD w/ a Vortech


I think your fuel is holding you back some, I'd go down in pulley size and ask your tuner about timing used at WOT

can you run 93?

I can, but the 93 up here is full of ethanol, The 91 was is a clean source.( with saying that I am planning on running a mix of 114vp fuels to the 91 for safety to make up 93-940. So... yes is the answer. ( but because of availability I have 91 set up)

I have just ordered is a new IC, it'll flow 1250 cfm and 32psi, the current CX racing I have is at 550 cfm +/-. I have been reading a bunch of articles, stating that they are pretty restrictive, but with saying that (my boost should be higher for same HP) arrggh.

Ive ordered a 3.125 pulley as well. TBH I haven't seen a Centri curve like this, when the let tuner off the throttle it was still climbing. The other thought I have is rev higher...... but I'm a scaredy cat. ( motor has 3000 miles on it and its a new install to me. FWIW).

So currently it's seem to be almost all motor to 4k rpm then I get into some boost.

Thanks for all your feedback, this setup( strokeretc) is all new to me.

 

[stkjock]

what's the issue with running 93 then? why you fear the E?

this is my dyno sheet

 

[Mustang dog]

Long tube headers, no cats, up to 15% ethanol in our 93, so in reality, it's a lower grade gasoline than clean 91. Only 2 brand station carry it, so harder to come by.

On another note we have no refineries here in our Province ( Alberta). Then the 93 sits in the ground because not a lot of people want to pay the premium. $1.00 -1.50 per gallon more.

91 is cleaner readily available, I can mix it up and its clean, and fresher than the 93. Sorry, for the long explanation....

But with saying that... if you were running a V-3, ( Paxton is bigger) on a fairly stock setup, and you are putting the same hp down as me..... not so sure needs mine needs some tweaking

 

[stkjock]

I had a V2, stock exhaust.

I'd still be inclined to run 93, despite your issues with the supply, you could find out when they are dropping a fresh tank of fuel, fill up a 55 gallon drum and keep it around home?

 

[eighty6gt]

Don't f with the ethanol fuel.

"Lots of fuel at WOT 12.4 AFR" - the graph shows richer, which is good.

"correction factor for the Mustang Dyno( I'm guessing) on 12% " - huh?

How much timing at WOT?

Puzey doing the dyno?

Is the car fun to drive?

 

[Mustang dog]

Agreed on the ethanol

I meant to say 12% difference butween mustang and dyno jet. Mustang being in the stingy side.

Not sure about timing, never asked because it has to go back in for tuning after the pulley down, hoping to finalize maybe a race only tune.

Yep MP is tuning it.guy knows his stuff.

Car is a lot of fun to drive and sounds good, it’s a new build with the typical hardware gremlins to sort out. I mean that’s half the fun right?

 

[jdlatil]

With your setup I don’t think your bypass valve is setup correctly.
With stage 3 cams and low vacuum, your bypass may not be allowing boost early enough.

Your set looks like a MMR setup, did you have this engine built?

Who’s stage 3 cams are you running?

 

[Mustang dog]

Yes it’s the MMR 1000se with stage 3 heads, and stage 3 blower cams (MMR) I’m the second owner of the motor. I bought it from the original who subsequently wrote off his car the summer it was installed. It had a ProCharger on it.

Ive been thinking this as well. I’ve t-d off the vacuum line at the FPS. My boost gauge also t’s in front of this BOV t and on the same line. I’m wondering if I shouldn’t tie right into the brake vacuum line(but it increases the length of vaccum hose.

I’ve noticed that my fuel pressure gauge( https://www.metcomotorsports.com/proddetail.asp?prod=MFP0007&cat=102) I’ve just installed is bouncing pretty wildly-(30-40) I’m wondering if I’m not getting true vaccum. New fuel pump, and new injectors.

With your setup I don’t think your bypass valve is setup correctly.
With stage 3 cams and low vacuum, your bypass may not be allowing boost early enough.

Your set looks like a MMR setup, did you have this engine built?

Who’s stage 3 cams are you running?

 

[jdlatil]

I have the same engine in my 2007 Mustang. It was a turbo car and decided to go back to a KB 3.2 supercharger and changed out to much milder car.

I have my boost gauge, fuel pressure regulator, bypass valve t’ed into FPS on fuel rail. My system does not use a BOV.

No familiar with Paxton setup what causes your boost to engage? Bypass valve? Looking online I see Paxton does use a vacuum bypass valve in original instructions.

Fuel pressure gauge should not be bouncing around like that of course.
Do you have return style fuel system?

 

[Mustang dog]

No I have the stock style fuel system non returnless.

It’s a belt style so the faster I go or spin the rpm. The more boost is produced.

 

[Mustang dog]

So I switched my vacuum line to pull vaccum before my boost gauge. I’ve lost a low rpm stumble, the FRP gauge has evened out with much less bounce.

Off to go get a vacuum line block/tree today.

 

[AndrewNagle]

So I switched my vacuum line to pull vaccum before my boost gauge. I’ve lost a low rpm stumble, the FRP gauge has evened out with much less bounce.

Off to go get a vacuum line block/tree today.

nice

 

[07Bossman]

Maybe I'm reading that graph wrong, but there's no hint you hit a Peak. Everything is still on the way UP.

Which in my mind, if that is the way you will drive it, you overshot your build goal. IMO, building an engine that peaks at 7200RPM and shifting 6250 RPM or less is futile. I'm actually surprised the stock intake and TB took you that high without any dropoff.