Question about boost....

[junior73]

Cliff notes: Installed a TFS Stage 1 cam, Cobra intake, shorties, offroad H-pipe along with a set of seriously worked heads on the 302. Put on a V3 SQ that is advertised as 5-6psi. I am running a UPR Boost pipe, 42's, and working the tune through a Quarterhorse:thumbsup1:. Problem is, I'm not registering anything over 3-4psi on my boost gauge:thumbsdown1:.

My question is this: Is this because
1. The heads, intake, cam, exhaust aren't stock
2. Am I being plagued by boost leakdown
3. Possibility of the gauge being faulty?

I'm showing 15in of vacuum at idle, so I don't think it's the gauge, but am puzzled by all of it.

Any ideas???

[Bizarro]

Where are you reading the boost from? How is it hooked up?


Cliff notes: Installed a TFS Stage 1 cam, Cobra intake, shorties, offroad H-pipe along with a set of seriously worked heads on the 302. Put on a V3 SQ that is advertised as 5-6psi. I am running a UPR Boost pipe, 42's, and working the tune through a Quarterhorse:thumbsup1:. Problem is, I'm not registering anything over 3-4psi on my boost gauge:thumbsdown1:.

My question is this: Is this because
1. The heads, intake, cam, exhaust aren't stock
2. Am I being plagued by boost leakdown
3. Possibility of the gauge being faulty?

I'm showing 15in of vacuum at idle, so I don't think it's the gauge, but am puzzled by all of it.

Any ideas???

[junior73]

It's run straight off the vacuum tree, where the A/C would hook normally hook up.

[Proline_Coupe]

get a boost reading off a port on the intake manifold..

[NC STANG GUY]

Cliff notes: Installed a TFS Stage 1 cam, Cobra intake, shorties, offroad H-pipe along with a set of seriously worked heads on the 302. Put on a V3 SQ that is advertised as 5-6psi. I am running a UPR Boost pipe, 42's, and working the tune through a Quarterhorse:thumbsup1:. Problem is, I'm not registering anything over 3-4psi on my boost gauge:thumbsdown1:.

My question is this: Is this because
1. The heads, intake, cam, exhaust aren't stock
2. Am I being plagued by boost leakdown
3. Possibility of the gauge being faulty?

I'm showing 15in of vacuum at idle, so I don't think it's the gauge, but am puzzled by all of it.

Any ideas???

I vote for #1. Also how many rpms are you turning it?

[junior73]

Proline_Coupe: I'll move the gauge feed today and see if that helps

NC Stang Guy: According to my datalogs, I was spinning at 5968rpms

[NC STANG GUY]

I really believe being you have ported heads,intake,cam and good exhaust is the reason behind the low boost.

Swap up to the 8 rib setup with the 6.87" crank and a 3.15 or so blower pulley at you'll see at least 10.5+.

My old Vortech setup saw 10.5 psi (UPR pipe.6.87/3.15) with ported GT40 Y alum heads,Holley intake,Lunati cam,good exhaust,etc. People told me they thought it'd make more boost but I believe it was because of the good flow of the engine it didn't make more. Made plenty of power though,521 rwhp at that 10.5 psi.

[crumbie]

"boost" is a relative number! blower is still pushing the correct amount of air - there is just less restriction with your h/c/i and exhaust.

[Droptop93]

"boost" is a relative number! blower is still pushing the correct amount of air - there is just less restriction with your h/c/i and exhaust.

X's 2....



Optimal would be a motor at operating RPM, blower zinging car hauling a-s-s and boost gauge reading 0. Doesnt mean you not making boost, just means your motor is using everything the blower is putting out. Now if you are reading 0 and car isnt pulling then you have a problem.

[junior73]

X's 2....



Optimal would be a motor at operating RPM, blower zinging car hauling a-s-s and boost gauge reading 0. Doesnt mean you not making boost, just means your motor is using everything the blower is putting out. Now if you are reading 0 and car isnt pulling then you have a problem.

It pulls like hell. Well, it should with good tires. It won't hold traction in first or second, and ran outta road before trying to bang third!

I may still go with a pulley swap, since I would feel better with an 8 rib setup as opposed to the 6 rib that came with it.

Good information though, and worth filing away, as I didn't understand the "relativeness" of boost/motor.

Thanks for the help y'all! Hopefully I can get it squared by Wednesday and make it up to Darlington and see what it will put down:thumbsup1:

[crumbie]

boost is measured in psi. or pressure (in lbs) per square inch. if you have less restriction, you have less pressure. but the same amount of air!

blow hair thru a small straw. you feel the pressure. then blow thru a bigger straw and you're moving the same air but there is less pressure.