Stock 9.8 turbo, E85 and 91 comparison
Hokiruu...I would say that your WG is not quite preloaded enough, judging by the posted torque curve peaking in the mid 4000 RPM range. Instead of running the 9.8 housing with minimal preload, I would try a 10.5cm housing with about 18-19 PSI of spring pressure. While you are at it, you may want to upgrade to an FP HD 18 PSI actuator too.
As it is you are leaving at least 10 WHP on the table by using the 9.8. Which would be fine if you had the gate preloaded so that your 16G would spool up faster. Otherwise set up as you currenty have it with hardly any preload, you might as well run the 10.5 and preload the hell out of it. Properly preloaded the 10.5 can spool up faster than your current setup AND give you 10-12 WHP additional up top as well.
In addition, the 9.8cm housing creates higher exhaust back pressure leading to steeper EGT's. Ultimately, your tuner can extract more upper-midrange and high end power from the 10.5 housing. This is an established certainty. The 10.5 properly preloaded is just better than the 9.8 setup as you currently have it adjusted with too little preload.
EDIT: I imagine that your turbo is still fitted with the stock actuator. Is it not? The stock actuator for running higher boost levels is not where it is at. This is especially true on an unported 9.8 housing which has a more restrictive turbine inlet area and thus produces higher flapper valve seat pressures at any given engine RPM and turbo shaft rotational speed. The lower rate spring in the stock actuator allows the flapper valve to lift off its seat easier, especially with little preload adjustment as you have it set up.
Finally, as "construct" pointed out in his earlier posted response, crushing the stock metal DV would move your entire power curve to the left significantly. The uncrushed DV contributes to the wimpy spool-up for obvious reasons. With both the diverter valve and the flapper valve lifting at unnecessarily low boost levels, you are shooting yourself in the foot.
As it is you are leaving at least 10 WHP on the table by using the 9.8. Which would be fine if you had the gate preloaded so that your 16G would spool up faster. Otherwise set up as you currenty have it with hardly any preload, you might as well run the 10.5 and preload the hell out of it. Properly preloaded the 10.5 can spool up faster than your current setup AND give you 10-12 WHP additional up top as well.
In addition, the 9.8cm housing creates higher exhaust back pressure leading to steeper EGT's. Ultimately, your tuner can extract more upper-midrange and high end power from the 10.5 housing. This is an established certainty. The 10.5 properly preloaded is just better than the 9.8 setup as you currently have it adjusted with too little preload.
EDIT: I imagine that your turbo is still fitted with the stock actuator. Is it not? The stock actuator for running higher boost levels is not where it is at. This is especially true on an unported 9.8 housing which has a more restrictive turbine inlet area and thus produces higher flapper valve seat pressures at any given engine RPM and turbo shaft rotational speed. The lower rate spring in the stock actuator allows the flapper valve to lift off its seat easier, especially with little preload adjustment as you have it set up.
Finally, as "construct" pointed out in his earlier posted response, crushing the stock metal DV would move your entire power curve to the left significantly. The uncrushed DV contributes to the wimpy spool-up for obvious reasons. With both the diverter valve and the flapper valve lifting at unnecessarily low boost levels, you are shooting yourself in the foot.
Last edited by sparky; Dec 9, 2011 at 07:46 AM.
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Ruu: Before going to the additional expense of replacing your existing fuel pump with another, more expensive unit, why not try modding your Wally by simply punching its pressure relief valve? This will probably resolve your lean issue at WOT. At least its worth a shot, don't you think? And best of all, it won't cost you a dime.
Thanks for dropping in Donour, its been a long time! Yeah, I'm taking it slow and progressive out here. First Autocross since 08 this Sunday.
If you rewire the single 255 with a relay it will bump the base fuel pressure up about 10 psi since it will not be using the low voltage relay anymore, however it will not overrun the fuel pressure regulator. I did this on my car when I switched to E85... may be a cheap solution if you find out what the voltage drop problem actually is.
So, any suggestions on how to best get to the bottom of this voltage issue?
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Hokiruu...I would say that your WG is not quite preloaded enough, judging by the posted torque curve peaking in the mid 4000 RPM range. Instead of running the 9.8 housing with minimal preload, I would try a 10.5cm housing with about 18-19 PSI of spring pressure. While you are at it, you may want to upgrade to an FP HD 18 PSI actuator too.
As it is you are leaving at least 10 WHP on the table by using the 9.8. Which would be fine if you had the gate preloaded so that your 16G would spool up faster. Otherwise set up as you currenty have it with hardly any preload, you might as well run the 10.5 and preload the hell out of it. Properly preloaded the 10.5 can spool up faster than your current setup AND give you 10-12 WHP additional up top as well.
In addition, the 9.8cm housing creates higher exhaust back pressure leading to steeper EGT's. Ultimately, your tuner can extract more upper-midrange and high end power from the 10.5 housing. This is an established certainty. The 10.5 properly preloaded is just better than the 9.8 setup as you currently have it adjusted with too little preload.
EDIT: I imagine that your turbo is still fitted with the stock actuator. Is it not? The stock actuator for running higher boost levels is not where it is at. This is especially true on an unported 9.8 housing which has a more restrictive turbine inlet area and thus produces higher flapper valve seat pressures at any given engine RPM and turbo shaft rotational speed. The lower rate spring in the stock actuator allows the flapper valve to lift off its seat easier, especially with little preload adjustment as you have it set up.
Finally, as "construct" pointed out in his earlier posted response, crushing the stock metal DV would move your entire power curve to the left significantly. The uncrushed DV contributes to the wimpy spool-up for obvious reasons. With both the diverter valve and the flapper valve lifting at unnecessarily low boost levels, you are shooting yourself in the foot.
As it is you are leaving at least 10 WHP on the table by using the 9.8. Which would be fine if you had the gate preloaded so that your 16G would spool up faster. Otherwise set up as you currenty have it with hardly any preload, you might as well run the 10.5 and preload the hell out of it. Properly preloaded the 10.5 can spool up faster than your current setup AND give you 10-12 WHP additional up top as well.
In addition, the 9.8cm housing creates higher exhaust back pressure leading to steeper EGT's. Ultimately, your tuner can extract more upper-midrange and high end power from the 10.5 housing. This is an established certainty. The 10.5 properly preloaded is just better than the 9.8 setup as you currently have it adjusted with too little preload.
EDIT: I imagine that your turbo is still fitted with the stock actuator. Is it not? The stock actuator for running higher boost levels is not where it is at. This is especially true on an unported 9.8 housing which has a more restrictive turbine inlet area and thus produces higher flapper valve seat pressures at any given engine RPM and turbo shaft rotational speed. The lower rate spring in the stock actuator allows the flapper valve to lift off its seat easier, especially with little preload adjustment as you have it set up.
Finally, as "construct" pointed out in his earlier posted response, crushing the stock metal DV would move your entire power curve to the left significantly. The uncrushed DV contributes to the wimpy spool-up for obvious reasons. With both the diverter valve and the flapper valve lifting at unnecessarily low boost levels, you are shooting yourself in the foot.
You will have to check voltage at the pump housing connector while actually driving the car. Make sure the fuel pump relay system is stepping up to high voltage and then see what the voltage at the same connector it is reading at WOT and report back... The large white wire is the + for the pump...
Had this exact same problem with my car!! Pump was maxed on 1000cc and needed an additional pump. Sean also tuned my car but I have not verified whether it was a real Walbro or not. I would assume though since I bought it off Tiago from VR Speed Factory.
Last edited by krisdlm; Dec 9, 2011 at 07:27 PM.
Yeah, Hokiruu, the IX turbo is definitely a good upgrade over the VIII/9.8 turbo. These are frequently available used(just check for shaft play) on EvoM and locally on NorCalEvo. The IX turbo is pretty impressive on E85. It is a great street/auto-x compromise IMO.
I have a couple of new Forge Racing VIII actuators sitting on the shelf. You can keep one of them if I get a ride in your Evo the next time that I am in SF. We'll install it and set the preload up nice and proper.
I have a couple of new Forge Racing VIII actuators sitting on the shelf. You can keep one of them if I get a ride in your Evo the next time that I am in SF. We'll install it and set the preload up nice and proper.
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Sorry I've been slow to reply to my own thread. I got away with lots of car prep for autocross Sunday, ran sunday and had to catch up on work/life/girl.
So, to be clear: I have a volt meter but it only has needle probes, no alligator clips. I'm going to have to expose the pump and either use alligator clips on the + white wire or have a brave buddy sit back there with no seat and hold a needle probe on it while I drive WOT?
Thanks a ton Sparky, that's a really generous offer. I'll take you out for a good dinner and drinks!
You will have to check voltage at the pump housing connector while actually driving the car. Make sure the fuel pump relay system is stepping up to high voltage and then see what the voltage at the same connector it is reading at WOT and report back... The large white wire is the + for the pump...
Thanks a ton Sparky, that's a really generous offer. I'll take you out for a good dinner and drinks!
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