I had my Evo X tuned on E85 over the weekend. We did a 91 tune and E85. My last 91 tune was completely stock w/boost pill. Since then I added:
TBE (AMS DP, Mil.spec 100 cell cat, T1R CBE)
AMS FMIC
RRE UICP
AMS Fuel Rail
DW1000s
Walbro 255
GST 3-port boost controller
Forge WGA

Both tunes over the weekend were strong through the midrange but fell off at the top end. The 91 tune was up 20hp through the midrange but made the same peak HP as stock. The E85 tune made 20-40hp less than X's with similar mods.

We suspected a boost leak but I tested it tonight and there's no leak until approximately 25-26psi when the stock BOV starts leaking. I am little confused as to why the car is falling off at the top end since I can't be holding a lot of boost with the stock turbo.

Any ideas???

 

there are some oem bov don't leak before 32psi (i read that somewhere) but some can hold only upto 25-27psi.. if you have a boost leak, you will only reach a certain point..probably around 8-9psi or no boost at all..the thing that makes it taper down is the way the stock ebcs is holding the boost and/or that's all the turbo can breathe at that rpm...

maybe what you could do is change to 3port and get a better wg maybe? or add more pre-load to your oem wg...

but what i don't get is that your e85 tune was making 20-40whp less than X's with similar mods with e85 too? or similar mods with just pump gas? if with similar mods with just pump gas then there is something wrong with your car...maybe damage compressor wheel? not sure though...let's wait for others' opinion...good luck man...

 

my stock bov couldnt hold past 27psi when i got tuned on e85. i swapped to a synapse bov.

 

You sure its not your wastegate? Id check to see if its getting stuck open, you may need to change the spring inside of it.

 

Sorry, I just edited my OP. I forgot to list the 3-Port boost controller and Forge WGA in my list of mods.

The 20-40 whp is on the E85 tune. The 91 tune looks good in the midrange compared to the pre-mod graph but tapers at the top equalling the 300whp of the stock tune.

I don't think an aftermarket BOV will help since the stock turbo isn't going to hold that kind of boost above 6000rpm. The motor seems to be falling off above 5500.

 

Do you have a copy of your logs?

 

I didn't grab any of the logs since we were pretty sure it was a boost leak and we knew we would have to finish the tune after fixing it.

I'll try to get some data from GST and I'll do some Evoscan pulls asap.

 

Triple check your IC Piping, I though my BOV was floating too, turns out my LICP was expanding at around 25 PSI at the collar, and allowing air to seep out, tighten down clamps, be sure the ends of your piping nearly meet the ends of the intercooler, clamp it down.

 

Here are some Evoscan plots from today.