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  1. #21
    LTX Master


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    Just something that needs to be pointed out.

    Pnyhntr stated to but the valve before the MAF... This is typically true for MAF equipped vehicles because you do not want to vent measured air. The pcm does not like it when we do things like that. However, some people do not like the sound of the valve and try to quiet things down by recirculating the bypassed air back into the intake of the blower... In this case, you can put the MAF on the inlet side, before the air gets plumbed back in (so the air doesnt get measured twice), or on the pressure side after the bypass valve (just like you would if venting the air to atmosphere like Pnyhntrs setup.

    Pnyhntr has the same bypass valve as me, and it's a very high quality piece. Exotic Performance Plus sells them for $360

    With the F1 procharger, your capable of easily eclipsing the capabilities of those 60# injectors.

    For sizing injectors, the idea is to figure for a good estimate of flywheel HP then oversize the injectors a little so you have room to grow.

    Here's a handy formula for injector sizing:

    Flywheel HP X BSFC / #of cylinders = Lbs per hr @ 100% duty cycle

    For a safe duty cycle of 80%, divide the result of the above equation by .8

    BSFC = Brake Specific Fuel Consumption, a good estimate for this on a SC'd motor is .55-.6 I use .6 as it tends to add a little cushion room.

    Example equation for 900 fwhp:
    (900 X .6) / 8 = 67.5 lbs per hour @ 100% duty cycle
    67.5 / .8 = 84.375 (85 lbs per hour @ 80% duty cycle)

    My with my 383 I had to move my base fuel pressure up to 65psi (from 45) to get my duty cycle down to about 80% with 75# injectors. At that pressure, they flow a little over 90lbs per hour. So I swapped them out for a set of 95's.

    As for the point that methanol is needed... It's really not ever needed if you don't need max effort out of pump gas. And depends on your current intercoolers ability to keep IAT's in check. With pump gas, the point were you need methanol is determined by the point at which you simply cannot make any more power without getting into problems. Once you get there, add some methanol and crank it up! The methanol will cool the IAT's, add octane to the fuel mixture, and allow you to run more timing. The cooler IAT's and increased timing is where you find additional power from methanol.
    - Justin

    Custom tuning with HpTuners and your most common standalones.
    Quote Originally Posted by WJ Birmingham
    Boost... Makes good motors better, and bad motors junk. http://www.yellowbullet.com/forum/im.../icon_eyes.gif

  2. #22
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    pnyhntr, fire67 - your details are appreciated and understood.
    I hear above 60# injectors are mostly sold for a different impedence - does this require modification to my eletrical plugs at the injectors?
    As I plan to increase my car from 10 to 15psi, I'll add the bypass valve as explained, determine injector size and ensure fuel supply is up to the job, and get the car tuned.
    Once the car arrives this week I'l know better exactly what hardware is installed and how.
    thanks for the TECH help ! I like this site best already
    95 Z28 FORGED 355, JE 8.5:1 PISTONS, 230/239 - .530"/.546", 114 @ 110 CAM, stock heads, Pacesetter longtubes, 10 PSI from ATI P-1SC Procharger, 60#, 4L60E, Yank3600, 9" 3.73, ET Street 28x12.5x15, 3450lb

  3. #23
    LTX Master


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    As far as going to low inpedance injectors - you just need an injector driver box like an Acceleronics Versa-fueler or AEM injector driver. All these boxes do is take in the output from the factory pcm, convert it to a peak and hold type signal and isolate the stock drivers in the pcm from the draw of the new injectors. They do require quite a bit of wiring to install though. As you will have to locate the injector wires in the harness, and then cut-splice the driver box in.

    As far as fuel supply goes... The equations I already provided can help with that... Use the injector size calculation at 100% duty cycle, then multiply by 8 to get total required volume... Then just make sure the pump you have or plan to get can supply that volume at full fuel pressure. With a 1:1 regulator installed and recieving manifold vacuum/boost, you will have Base Fuel pressure (45psi) + boost pressure (15psi) = 60psi total.
    Now even though injectors flow more fuel at higher pressures, this is not the case with a 1:1 regulator. Simply because the proportionate increase in fuel pressure is used to keep flow the same when you have pressure in the manifold trying to keep the fuel from coming out.
    - Justin

    Custom tuning with HpTuners and your most common standalones.
    Quote Originally Posted by WJ Birmingham
    Boost... Makes good motors better, and bad motors junk. http://www.yellowbullet.com/forum/im.../icon_eyes.gif

  4. #24
    LTX Master


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    Hey Fastbird: on a side note... I did some maintenance on a '03 Henessey Venom Viper today. It had twin tial style 50mm BOV's with the twin turbo's. They wer not opening at idle.

    So I messed around with them a little bit and managed to get them to hold open at idle ever so slightly... Just enough opening to hear some air hissing out.

    So I got ever more curious and took one off and disasembled it. And disasembled my ATI race valve right next to it. Wish I had a camera with me because they are almost identical. The spring pressure was even very close to the same (feeling by hand). The main difference was the size of the diaphram (sp?). The ATI diaphram was quite a bit larger in diameter. Which means that any vacuum it sees has more surface area to pull on. Which would over come the spring pressure easier and enable it to hold the valve open at idle with very little vacuum.

    So I reasembled both, and used a mighty vac with a gauge to see what kinda vacuum was needed to open the valves. With normal adjustements on both, the Tial style needed almost 18" while the ATI would open at 5". The ATI opened fully at 5" so I loosened the set screw on the tial style and got it open ever so slightly at 11"

    Based on my disection, the spring is only there to hold the valve shut... If your boost level manages to push the valve open, you would need to tighten the set screw or get a stiffer spring. The diaphram is what opens the valve, so it's size is directly related to how much vacuum is needed to over come the spring pressure.
    - Justin

    Custom tuning with HpTuners and your most common standalones.
    Quote Originally Posted by WJ Birmingham
    Boost... Makes good motors better, and bad motors junk. http://www.yellowbullet.com/forum/im.../icon_eyes.gif

  5. #25
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    thank you for the great info!
    UPDATE:
    Car arrived
    has PISC head unit, twin intercoolors - looks like the stadard 93-97 system.
    has a 230/239@ .050 with .530/.546 lift on a 114, installed at 110 intake center line.
    Car idles with 10 on the vacuum gauge - raise slightly with rpm.
    has 60lb injectors, Crane 600 ignition, Pacesetter longtubes with duals and was Thunder tuned.
    Can I still raise boost as outlined in the previous posts?
    Or am I at about a safe setting?
    I have not determined the heads - but just mild porting and told forged internals. I do have the JE reverse dome piston receipt and bill for shop labor in line with a hot rebuild cost.
    95 Z28 FORGED 355, JE 8.5:1 PISTONS, 230/239 - .530"/.546", 114 @ 110 CAM, stock heads, Pacesetter longtubes, 10 PSI from ATI P-1SC Procharger, 60#, 4L60E, Yank3600, 9" 3.73, ET Street 28x12.5x15, 3450lb

  6. #26
    LTX Master


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    Sounds like you should enjoy it as is... That's a fairly small head unit. If you aren't satisfied with the current power level, you really need to determine whether or not you can safely spin that little head unit any faster.

    I'm not sure of a P1SC head unit's max impeller speed... But it is readily available on the Procharger's website.

    Equation for impeller speed: CP/BPxEngine RPMx step up ratio=impeller speed
    CP= Crank pulley diameter
    BP= Blower pulley diameter
    Engine RPM= rev limiter setting (max safe RPM for engine)
    Step up ratio= Internal step up ratio of blower (D1sc is 4.10)

    Figure that out and you will be able to determine whether you can or cannot spin your head unit any faster to raise the boost level.
    - Justin

    Custom tuning with HpTuners and your most common standalones.
    Quote Originally Posted by WJ Birmingham
    Boost... Makes good motors better, and bad motors junk. http://www.yellowbullet.com/forum/im.../icon_eyes.gif

  7. #27
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    thanks
    max is 62,000 rpm and the F1 is 70,000.
    I'll be awhile to measure pulleys and probably just drive as is - it's not slow
    how are you getting 15psi out of yours?
    95 Z28 FORGED 355, JE 8.5:1 PISTONS, 230/239 - .530"/.546", 114 @ 110 CAM, stock heads, Pacesetter longtubes, 10 PSI from ATI P-1SC Procharger, 60#, 4L60E, Yank3600, 9" 3.73, ET Street 28x12.5x15, 3450lb

  8. #28
    LTX Master


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    It's pulleyed to max the blower out at 6500 engine rpm... 15psi is all that it would make with the twin highflow intercoolers and leaky stock Procharger bypass valve (the tube thing). I have a Reichard Ultra Grip blower pulley (3.25") and the stock procharger (7.625") crank pulley.

    I have not yet tested it with the Procharger race bypass because I have not been able to bring the motor up that high in rpm's yet... Still working at the tune.

    I have however been strongly considering eliminating the intercoolers all together and running Sunoco Maximal 116 race gas and using the methanol to cool the charge temps down...

    I would have to change pulleys though and start off with a lower boost level to make sure I don't grenade something. It would be on the ragged edge of safety for the motor, probably closer to the melt some shit down side of that 'fine line'.
    Last edited by Fire67; 09-17-2008 at 02:40 PM.
    - Justin

    Custom tuning with HpTuners and your most common standalones.
    Quote Originally Posted by WJ Birmingham
    Boost... Makes good motors better, and bad motors junk. http://www.yellowbullet.com/forum/im.../icon_eyes.gif

  9. #29
    Long Live the Opti


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    Quote Originally Posted by Fire67 View Post
    Hey Fastbird: on a side note... I did some maintenance on a '03 Henessey Venom Viper today. It had twin tial style 50mm BOV's with the twin turbo's. They wer not opening at idle.

    So I messed around with them a little bit and managed to get them to hold open at idle ever so slightly... Just enough opening to hear some air hissing out.

    So I got ever more curious and took one off and disasembled it. And disasembled my ATI race valve right next to it. Wish I had a camera with me because they are almost identical. The spring pressure was even very close to the same (feeling by hand). The main difference was the size of the diaphram (sp?). The ATI diaphram was quite a bit larger in diameter. Which means that any vacuum it sees has more surface area to pull on. Which would over come the spring pressure easier and enable it to hold the valve open at idle with very little vacuum.

    So I reasembled both, and used a mighty vac with a gauge to see what kinda vacuum was needed to open the valves. With normal adjustements on both, the Tial style needed almost 18" while the ATI would open at 5". The ATI opened fully at 5" so I loosened the set screw on the tial style and got it open ever so slightly at 11"

    Based on my disection, the spring is only there to hold the valve shut... If your boost level manages to push the valve open, you would need to tighten the set screw or get a stiffer spring. The diaphram is what opens the valve, so it's size is directly related to how much vacuum is needed to over come the spring pressure.

    Hmmmm.....interesting. So would this mean that with a spring change the BOV's would work just fine in place of the more expensive "blower specific" bypass valves??? Either way, thanks for taking the time to break those down and look at their innards and reporting back like that. Cool thing to find out.
    Quote Originally Posted by Ryan Stout View Post
    I would try to work my neck muscles but I'm not invited to the LS guy parties.

  10. #30
    LTX Master


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    Quote Originally Posted by Fastbird View Post
    Hmmmm.....interesting. So would this mean that with a spring change the BOV's would work just fine in place of the more expensive "blower specific" bypass valves??? Either way, thanks for taking the time to break those down and look at their innards and reporting back like that. Cool thing to find out.
    The only thing I could see possibly go wrong with that is the the spring is gonna have to have a tension that is higher than your boost number X the surface area of the valve that holds the air back. Probably could be done, but it would be a fine balancing act.
    - Justin

    Custom tuning with HpTuners and your most common standalones.
    Quote Originally Posted by WJ Birmingham
    Boost... Makes good motors better, and bad motors junk. http://www.yellowbullet.com/forum/im.../icon_eyes.gif

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