Boost on 91 OCT

[electr0]

i know this is a noob question, and i looked through the forums and cant find it.. i must suck at searching so dont flame me

i have a hallman pro rx and defi d boost gauge and im on 19.5psi right now. If i get full 3'' exhaust, is it safe to run 21psi daily driven? I just dont want to find out the hard way that it isint if you know what i mean.

[TrickedOutEVOVIII]

there are ppl doing that w/out those mods...you'll be fine

T

[Blaze]

without injectors or tuning, I'd recomend 19-20 PSI.
An extra psi or two may help or hurt you.
(you gotta log it to see)

19-20 is safe.

[silvery_eagle]

wow blaze is on fire today... +18 already
erm... I have works P2 flash with no MBC....is it normal to have boost spike to 1.5bar and taper down to 1.4?

[4g63evo05]

im running 1.5 bars on my evo and it is completly stock. it runs fine

[DTunedEvoX]

wow blaze is on fire today... +18 already
erm... I have works P2 flash with no MBC....is it normal to have boost spike to 1.5bar and taper down to 1.4?


Yes especially with the 05 because of the bigger 10.5t housing ..

[ArBizZzLe]

Shiv from Vishnu is saying it's pretty safe to run even 23psi on the Evo IX's on 91 octane thanks to the revised coolant passages.

[ultraflip]

1.4 bar on 91 octane... i love my safety

[ngtcrawler97]

what about an 8 w/ TBE & boos controller 19-20 or higher :-\

[ultraflip]

i've got gray stage 1+ mods and i'm still only boosting @1.4 bar for paranoia reasons

[evoibad]

Is this holding boost till redline, if not what does it taper to.

[TrickedOutEVOVIII]

on the stock turbo you WILL NOT hold boost "til redline" contrary to the popular myth here on socal where you see everyone and their mom say "dude, my shit holds 22 pounds til redline!"

simply put, it aint true!! the only ppl that hold solid boost through redline and i mean really hold it, like when it looks like the needle is stuck in that position, are the ppl with upgraded turbos. the fact of the matter is that the stock turbo's characteristics will not allow you to do so. it runs out of breath...its a midrange turbo...no where near a top end turbo, even with all the top end fixes.

im just letting you know so you dont beleive the myth going around...it will taper...just a fair warning

T

[Terry S]

Shiv from Vishnu is saying it's pretty safe to run even 23psi on the Evo IX's on 91 octane thanks to the revised coolant passages.


Slight caveat to that; it's safe to PEAK at 23psi on the IX but with the standard taper. DO NOT read that as "slap on an MBC & hold 23psi to redline no problem mon!"

Terry S

[electr0]

Yea so i should be running 20 on my 2003 evo 8 9.8 hotside with hallman pro mbc and a 3'' TBE?

This is holding to redline.. I honestly dont think my boost tapers because i stare at the gauge when im at WOT and it doesnt drop down at all...

[trinydex]

the 9 turbo actually does a good job of holding boost til redline only tapering at the very end. you can see this in most of the dynosheets, it does just as well as the 20gs on pump gas.

[haans brix]

terry s: when you say with the standard taper...wat exactly do you mean? does the turbo do that automatically or do adjustments have to be made?

[trinydex]

stock turbo will taper boost automatically due to flow limitations of the compressor.

[nj1266]

Yea so i should be running 20 on my 2003 evo 8 9.8 hotside with hallman pro mbc and a 3'' TBE?

This is holding to redline.. I honestly dont think my boost tapers because i stare at the gauge when im at WOT and it doesnt drop down at all...

Gauges are inaccurate. If you gauge is showing 20 psi peak boost, then more than likely the actual number is 18.5-19 psi. You will only know your boost peak and taper if you log it. I have been logging my boost for a while and on every log there is taper. The link below shows you the boost by rpm of 13 logs. You will note the boost taper as the rpms increase after boost peak.

http://www.sr20deracing.com/EVO/boost_taper_13.jpg

[wj4]

my 05 with doctor gray stage 1 peaks at 1.6bar for 2-3 seconds and tapers down to 1.4bar.
i originally had it set to 1.5bar and tapered down to 1.3bar, but the doc himself turned up the boost for me.

[haans brix]

im spikin at 1.69 bar then it tapers down from there and im stock except for a drop in filter

[wj4]

im spikin at 1.69 bar then it tapers down from there and im stock except for a drop in filter

what do u taper down to?

[kimletrim]

I hold 1.8 bar all the way to a little bit past redline.

[haans brix]

I hold 1.8 bar all the way to a little bit past redline.



are you stock?
it says in your sig to ask you how

[haans brix]

im not sure wat it tapers down to wj4 i mite turn it down a little bit just to be on the safe side

[trinydex]

one more thing about boost on 91 octane... the 9s can boost a tad bit more than the 8s due to revised cooling in teh cylinder head.

[nj1266]

I stopped using 91 octane gas only. Now I mix 3.5 gallons of 100 octane with 9.8ish gallanos of 91 octane to get 93.xx octane gas. I used to get those spikes in the AFR indicating blown spark with 91 octane gas, but with the 93 octane it is GONE. No more spikes and the car loves running on 93 octane gas. The Evo was designed to run on 93 octane gas.

With 93 octane I do not have to worry about the boost I run as much as I worry with 91 octane. On 93 octane I can boost to 22-23 psi with little worry.

[trinydex]

hope that alaskan pipeline leak doesn't hurt you too bad.

[nj1266]

hope that alaskan pipeline leak doesn't hurt you too bad.

I would not buy an Evo, if I could not gas it and maintain it. I am not one of those people who buy things they cannot afford.

[JDMC-WestEVO]

my evo was dynoflashed and it holds boost up to 7500 most of the time once in a while i get a little taper from 21 to 20 but that is after 6700

[Evolution.VIII]

I may be mistaken, but the last brochure I saw advertised peak boost @ 20.82 tapering to 17.

[GokuSSJ4]

I may be mistaken, but the last brochure I saw advertised peak boost @ 20.82 tapering to 17.
are you referring to a completly stock car ? and if so some of them get spikes of 22-23psi near midrange...

[projektevolutionix]

i am runnin 3 in catback, test pipe, and downpipe and i am running 20 psi. runs fine haven't had any problems so far

[j_nizzle]

i am runnin 3 in catback, test pipe, and downpipe and i am running 20 psi. runs fine haven't had any problems so far



stop ressurrecting a bunch of threads to up your post count!!!

[MRchnk]

sorry for barrowing the thread but how about pure 100 octane??? what is still relatively safe??

[Skiracer]

I run 25PSI on 100 octane O0

[ganma]

i spike to almost 1.7 bar also....don't know if it's normal on 91. mods are tbe and hks drop in filter. no tune

[RPD_FKTARD]

1.7 is very dangerous.. sorry.. you should get boost controller to turn it down a bit.

[zum96spd]

i spike to almost 1.7 bar also....don't know if it's normal on 91. mods are tbe and hks drop in filter. no tune


no u don't...