Where is it "known" or better yet proven?

 

FWIW, My opinion is that the MBC is not bypassing enough air because the ports are smaller than the BCS that came with the car. Because it is not bypassing enough air there is a stronger signal to the wastegate which means more taper. MIVEC has about as much to do with taper as what fuel is in the car. Unless it was GREATLY mistuned I am not quite with you on it being the cause.

To illustrate:

I have a restrictor pill removed BCS with an additional bleed port. Bleed valve closed I hit 25psi at peak torque and taper to 22-23 by redline. When I open the bleed valve I get pretty much the same taper curve no matter what the initial boost is. However I can tune my target boost value lower at lower rpm and see 25 psi at peak torque and 25 psi at redline.

I have a friend with an MBC that was seeing peak boost of 29psi and it tapered to 21 by redline. Either buy an FP WG actuator or mod the car differently to achieve the same goal. Keep in mind that if through an aftermarket actuator on there you will have alot more boost even with the MBC cranked all the way closed.

 

You guys at Works are full of CRAP. A friend of mine called me yesterday and he has your brain flash. He is so angry at you guys. He paid $550 for his flash and now that he was able to get it unlocked he found out that your flash is marginally leaner than stock (afr around 10) and you barely even touched the timing on his 05 Evo 8.

Unfortunately, my friend did not consult me before getting his ECU flashed. I would have warned him to stay away from you guys. But he thought "that you get what you pay for" and since your prices are hyper inflated, he wrongly assumed that he is getting a good tune.

Thanks god for Ecuflash and MJ's unlocker tool so we can really know who is the legitimate tuner and who is the poseur in the tuning industry.

 

It must be cause it had some "proprietary" tuning information in it.

 

+1

I've got the same setup. My car peaks at 23.5 psi and tapers to 22 at 7000 rpm. If I want, I can set the boost to 23 psi at 7000 rpm by readjusting the MWGDC maps.

 

From my reading on this subject on the Evo 8, there are two reasons for taper. The first is a function of the ECU and the second because the turbo runs out of breath at the top end. The stock turbo is a low end mid range trubo and has reduced effeciency at the top end.

You can remove one taper by tuning your ECU and/or using a Boost Controller, but the other taper can only be removed by going to a bigger turbo. But going to a bigger turbo will move your power curve about 1000 rpm higher. So you spool @ 4500 rpm rather than 3500 rpm and your daily driveability suffers.

Basically, you can live with the taper and enjoy the low end sppol up and torque or go with a bigger turbo that will eliminate the taper and lose early spool up and torque.

 

MIVEC has a lot to do with taper.

I've had a IX and a VIII and yes the IX tapers more. The MIVEC on the IX is the reason it tapers more.

Also, to all you people making any claim about how much or how little taper you have, go buy a dataloggin system with a MAP sensor then report back. Most gauges are inaccurate.

 

John -- Would you please elaborate on your setup? I would LOVE to hit 25 psi and taper to 22 by redline ....How did you add an additional bleed port? Also, have you found a way to hit 25 psi in 3rd gear and hold to 22 psi by redline and do the same for 6th gear? I am finding that the extra load is increasing the boost in 6th -- so I peak at like 22 in 3rd and more like 24 in 6th...

Thanks a ton!!

 

Guyz, please ignore my previous post. I just pulled my dynograph sheet and confirmed that the boost tapers to 16psi by 7000 rpm on '3rd gear' pull. Sorry about the confusion.

 

 

Quoted for truth. A lot of people would be surprised to see how inaccurate their boost gauges can be and leading them to believe they are holding 20psi or so till redline in a IX when in reality they taper down to like 16-17psi thanks to MIVEC. No other way around this, but honestly who cares, we still make more power than the VIII's with less bolt ons anyways.

 

So if I get this Forge wastegate deal and install it that will correct my taper problem with boost?

 

I think the fact that there is more taper in the IX map versus the VIII map is as much the boost load and wastegate duty cycle maps as anything. Then compare the ver 13, 14, and 15 Roms for the IX and you will see even more programmed taper.

The best way to check for gauge accuracy is exactly what you said. However you can also check it against other boost gauges to see. I have checked mine against an Isspro and a stewart warner and its on compared to all of them.

 

Is the taper less evident on 5th (or 4th) gear?

 

I pulled my MR boost gauge and compared its reading to several laboratory-grade gauges. The MR gauge was mostly within +/- 0.5 psi of the lab gauges, and was never more than 1 psi off except out past 25 psi.