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Peaking out too soon and high duty cycle

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Old 01-17-2007, 11:51 PM
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Default Peaking out too soon and high duty cycle

Here you guys try to take a stab on this one. It's peaking out too early and the injectors are almost maxing out, around 80% duty cycle. Notice how the torque just drops at 7k rpms.

-b18c1 84mm block
-itr cams
-victor x manifold w/72-70 throttle body
-750cc injectors
-gt35r turbo
-walbro 255hp fuel pump




Modified by faSHOwidIT at 1:15 PM 1/18/2007
Old 01-18-2007, 09:16 AM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

what ya got for fuel pump
Old 01-18-2007, 12:15 PM
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Default Re: Peaking out too soon and high duty cycle (slodel)

walbro 255hp and also forgot to mention the turbo is a gt35r.
Old 01-18-2007, 12:16 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

whats the PSI level?
Old 01-18-2007, 01:03 PM
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Default Re: Peaking out too soon and high duty cycle (93supercoupe)

if you're talking about turbo it was set at 14lbs but creeped to 16lbs at peak, and as far as fuel pressure, 60psi at WOT
Old 01-18-2007, 03:00 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

is the car tuned. i hope so. or is this just dyno graph without tuning
Old 01-18-2007, 03:18 PM
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Default Re: Peaking out too soon and high duty cycle (postman)

car is dyno tuned
Old 01-18-2007, 03:55 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

What EMS are you running? And how is your fuel multiplier. If that is screwy it will throw those numbers all crazy. How do your timing maps look for the high cam area?

Jason
Old 01-18-2007, 04:04 PM
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Does the fuel pressure stay at 60psi and never drop off after hitting full boost?
Old 01-18-2007, 04:33 PM
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Default Re: Peaking out too soon and high duty cycle (Pro-Am 1934)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Pro-Am 1934 &raquo;</TD></TR><TR><TD CLASS="quote">What EMS are you running? And how is your fuel multiplier. If that is screwy it will throw those numbers all crazy. How do your timing maps look for the high cam area?

Jason</TD></TR></TABLE> hondata s200. not sure what the fuel mutiplier is nor how the timing maps look. I didn't tune it myself.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostfed.com &raquo;</TD></TR><TR><TD CLASS="quote">Does the fuel pressure stay at 60psi and never drop off after hitting full boost?</TD></TR></TABLE> We were watching the fuel pressure guage and it was shaking at 60psi but that could be from the vibration. but yes it was hitting 60psi in high rpms also.
Old 01-18-2007, 04:59 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

theres been alot of threads about there injectors maxing out too soon. if i remember correctly didnt htey all say there fuel damper was bad or something?
Old 01-18-2007, 05:01 PM
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Default Re: Peaking out too soon and high duty cycle (komat)

i'm going to upgrade my fuel pump power lines and also run a better fuel pressure regulator, hopefully that'll fix the problem. but i still need more experienced people to give me some pointers.
Old 01-18-2007, 06:16 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by faSHOwidIT &raquo;</TD></TR><TR><TD CLASS="quote">i'm going to upgrade my fuel pump power lines and also run a better fuel pressure regulator, hopefully that'll fix the problem. but i still need more experienced people to give me some pointers.</TD></TR></TABLE>

im running stock lines and stock fpr with 1000cc. at 420hp my duty is only at 65-68%
Old 01-18-2007, 07:21 PM
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Default Re: Peaking out too soon and high duty cycle (komat)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by komat &raquo;</TD></TR><TR><TD CLASS="quote">

im running stock lines and stock fpr with 1000cc. at 420hp my duty is only at 65-68%</TD></TR></TABLE> i've heard that aftermarket fprs as b&m, vortech, etc. that mounts onto stock fpr can cause problems when high boosting also.
Old 01-18-2007, 10:35 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

Need some pointers......although the car feels good and fast as a bat, is peaking out at 7800rpms with itr cams and victorx manifold normal? and also 83% duty cycle normal at this hp level with my injectors? it doesn't seem right?
Old 01-19-2007, 08:39 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

ttt
Old 01-19-2007, 08:57 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by faSHOwidIT &raquo;</TD></TR><TR><TD CLASS="quote"> i've heard that aftermarket fprs as b&m, vortech, etc. that mounts onto stock fpr can cause problems when high boosting also. </TD></TR></TABLE>

B&M is horrible... especially when used with Walbro 255 HP pumps. Stock works just fine believe it or not.

What is the static fuel pressure? What are your air/fuels? 750's should be able to get you at least 450ish whp depending on static fuel pressure.
Old 01-20-2007, 01:05 AM
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Default Re: Peaking out too soon and high duty cycle (PrecisionH23a)

what problems can the two, b&m fpr with 255walbro fuel pump cause? unfortunatly i don't have the print out of the a/f graph but if i remember, it's between 11 and 12. just to double check on the static fuel pressure i'll get back to you on that tomarrow when i get the chance to check the car out. i could of sworn it's 60 but i'll have to double check.
Old 01-20-2007, 07:01 AM
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Default Re: Peaking out too soon and high duty cycle (PrecisionH23a)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">

B&M is horrible... especially when used with Walbro 255 HP pumps. Stock works just fine believe it or not.

What is the static fuel pressure? What are your air/fuels? 750's should be able to get you at least 450ish whp depending on static fuel pressure.</TD></TR></TABLE>

was thinking the static was a little low. and agreeing about the b and m's. use the stocker, and if that static isnt enough. get a good rail mounted or external reg maybe upping to 50 psi static should help?
Old 01-20-2007, 09:00 AM
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Default Re: Peaking out too soon and high duty cycle (boostedcivicsir)

do this it is cheap. The most expensive thing is the Aeromotive FPR. Throwing money at the problems trying to fix anything doesn't help most of the time, I found out the hard way. Also get rid of that little fuel damper on the stock fuel rail feed side if you have one.( TAKE IT OFF!). That little $5 piece of shi... had me and alot of ppl scratching our heads for about 2 mnths. Also what are your wideband readings. Post up your complete set-up in detail. Good Luck!



parts list:

-1) AeroMotive FPR 1:1 ratio
-1)stock fuel rail
-2) M12x1.25 to -6AN Male fittings XRP #700903 ( on the stock rail use a pipe wrench and a big adjustable wrench to screw out the threaded stock fuel rail feed insert).
-1) -6AN male fitting with a pipe thread male end (you will need to drill and tap where the stock FPR sits on the stock rail, the size is up to you.)

After that you can figure out what hose and hose fittings you want to run.


Modified by VtecCarHauler at 10:11 AM 1/20/2007


Modified by VtecCarHauler at 10:16 AM 1/20/2007


Modified by VtecCarHauler at 1:51 PM 1/22/2007
Old 01-20-2007, 09:31 AM
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Default Re: Peaking out too soon and high duty cycle (komat)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by komat &raquo;</TD></TR><TR><TD CLASS="quote">theres been alot of threads about there injectors maxing out too soon. if i remember correctly didnt htey all say there fuel damper was bad or something?</TD></TR></TABLE>

lol, I was thinking the same thing - it actually helped 2 car in like a month.

The only problem I see is torque falling off. 80% DC isn't going to rob you of power per se, assuming its at least somewhat accurate of a %. 750's yeild ~524hp at 100%, so thats ~420 at 80%. Doing my rough 750 x 0.7 (constant) x .80 = yeilds the same, so my guess is the cams aren't tuned well, compression/leakdown is bad in a cyl, or some other problem that isn't major, but a consistent power-robber.
Old 01-20-2007, 11:49 AM
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Default Re: Peaking out too soon and high duty cycle (HiProfile)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HiProfile &raquo;</TD></TR><TR><TD CLASS="quote">

lol, I was thinking the same thing - it actually helped 2 car in like a month.

The only problem I see is torque falling off. 80% DC isn't going to rob you of power per se, assuming its at least somewhat accurate of a %. 750's yeild ~524hp at 100%, so thats ~420 at 80%. Doing my rough 750 x 0.7 (constant) x .80 = yeilds the same, so my guess is the cams aren't tuned well, compression/leakdown is bad in a cyl, or some other problem that isn't major, but a consistent power-robber.</TD></TR></TABLE> funny that you brought it up, cam timing was untouched, and also leakdown as well as compression test is all good. i will be doing that fuel upgrade soon.


Modified by faSHOwidIT at 1:11 PM 1/20/2007
Old 01-20-2007, 12:16 PM
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Default Re: Peaking out too soon and high duty cycle (faSHOwidIT)

i steped up to 1000cc on my set up. i had 880cc and was getting close to maxing them out at around 20+ psi
Old 01-31-2007, 10:16 AM
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Default Re: Peaking out too soon and high duty cycle (Mr HYDE)

fuel pressure is at 52lbs with vacuum hose off.
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