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Author Topic: A question about stock boost  (Read 673 times)

Rod Bacon

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  • Posts: 24
    • 1993 XR2
A question about stock boost
« on: April 24, 2017, 12:18:34 AM »

I installed a digital boost gauge over the weekend, and see that my car is topping at 8 PSI. I'm curious about what I've read on this forum in that there appears to be 2 distinct schools of thought about stock boost levels. Some claim 5-6 PSI is typical, but other posts suggest that the wastegate opens at 8 PSI (as I'm seeing). If 8 PSI is correct, how can 5-6 PSI be considered typical? Am I misreading or misinterpreting something?
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greywolf27030

  • Old-Timer
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  • Posts: 711
    • 88 Festiva, 91 Capri, 91 XR2
Re: A question about stock boost
« Reply #1 on: April 24, 2017, 08:35:18 AM »

I like your question Rod.  My stock gauge tops out at 5-6 PSI.  I'm new to this turbo thing and am wanting to get intouch with my wastegate and what about a POV.  My previous experience with turbos was my Corvair 180HP and neither was invented yet.

Jack Byrd
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Rod Bacon

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  • Posts: 24
    • 1993 XR2
Re: A question about stock boost
« Reply #2 on: April 25, 2017, 08:17:54 PM »

From what I've read, there seems to be some concern about the accuracy of the stock gauge. Having said that, mine seems to be pretty accurate when compared to my new digital one. The stock gauge range is 0-1 BAR (0-14.5 PSI) and the needle peaks just above the halfway mark (so 8 PSI would make sense). Is yours peaking below the halfway mark?

I installed the digital gauge because I'm installing a boost controller and want to set the boost just below the 10 PSI fuel cut-off switch is reached. I'm also replacing the stock recirculating boost valve with a splitter (recirc/bov) but that's purely for the noise. LOL.
« Last Edit: April 25, 2017, 08:24:24 PM by Rod Bacon »
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Casper

  • Jr. Member
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  • Posts: 67
    • 93 XR2 and 91 Turbo Clubsprint (tribute)
Re: A question about stock boost
« Reply #3 on: April 26, 2017, 08:28:47 AM »

My in-dash boost gauge reads at about 0.5 bar (or about 7psi) but my new separate boost gauge reads at 9psi.  I do have a manual boost controller but haven't played with it yet - just watching the new boost gauge to see what it is doing.  I thought is was set to a higher boost as it was hitting the boost cut-off often when revving hard (I do some super sprints on track) - I assumed about 12psi - I now also have a rocketchip so that is disconnected and it sits on 9psi.  No cut-out and it runs hard.
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Rod Bacon

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  • Posts: 24
    • 1993 XR2
Re: A question about stock boost
« Reply #4 on: April 26, 2017, 06:49:26 PM »

Thanks for the info Casper. I'm waiting for Rocketman to get back from his hiatus later this year, so I can get a rocketchip too.
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Casper

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  • Posts: 67
    • 93 XR2 and 91 Turbo Clubsprint (tribute)
Re: A question about stock boost
« Reply #5 on: April 28, 2017, 10:30:53 AM »

Now it is time to adjust the boost controller and see what some extra boost will do.....
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Rod Bacon

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  • Posts: 24
    • 1993 XR2
Re: A question about stock boost
« Reply #6 on: May 06, 2017, 05:07:17 AM »

To answer my own question... I picked up another XR2 Turbo today, completely stock with recently rebuilt engine. It seems only make about 5-6 PSI boost (on the stock gauge) so I'm thinking that the 3" exhaust on my other XR2 has a lot to do with how much boost these cars can build. I suspect that a stock car will never actually get near the wastegate spring pressure, let alone the 10 PSI safety switch.
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SHOwn

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    • 91 XR2
Re: A question about stock boost
« Reply #7 on: May 07, 2017, 01:56:18 PM »

Maybe in very cold weather going uphill at under 3000 rpm a stock capri might trigger the waste gate and over boost warning. If you go with a larger exhaust it is easy to run into over boost and waste gate activation, as well as the cut-out, but I heard what you said, stock would be hard to run into those conditions.
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R. Powell
'91 XR2, LM 16" Chrome Drifters, White Gauge Faces, Kuhmo 40's, Big Brake UG, 2.5" Mandrel Bent CATback, BMW318 Heated Seats, `94 console, '99 Dodge Neon Spoiler, '94 XR2 Sideskirts Bumpers and taillights, Fresh Basecoat-Clearcoat Cardinal Red (Jul2014), vj11/vj14 hybrid, manual boost CTL.