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I was just wondering what is the highest boost you guys run on the stock twins on some good gas.... just for drags not really for long runs..... thanx Kevin ps im running 18 but it will go higher but i thought id poll everyone before going higher... thanx
 
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Kevin Hornsby said:
I was just wondering what is the highest boost you guys run on the stock twins on some good gas.... just for drags not really for long runs..... thanx Kevin ps im running 18 but it will go higher but i thought id poll everyone before going higher... thanx
@104 Octane, you can prolly run up to 25 psi. I've ran mine (in cool SoCal weather) upto 1.4 bar on ~97 octane.

But the ONLY way to know is to keep up turning up the boost until you hear detonation. :p

Regards,
Brian
 

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18psi??? man i run 1.5 and thats about 22 psi...this is with 93 pump.....what the does detonation sound like??
 
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It will sound like a can of marbles. Definitely something to avoid long term, usually happens on hot days during normal driving.
 

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I ran mine with the hose pulled off and would get 22psi. Turbos did nto last to long after that. 80)
 
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I thought the mkiv has a knock sensor how can you detonate if it retards the timing automatically.... thats why i bought the car is so i dont have to worry about things like that.... you can run 20 pretty safely then.... thanx Kevin...
 

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Kevin Hornsby said:
I thought the mkiv has a knock sensor how can you detonate if it retards the timing automatically.... thats why i bought the car is so i dont have to worry about things like that.... you can run 20 pretty safely then.... thanx Kevin...
But, running with lots of timing retard is bad. It leads to very high EGT's since the A/F mixture is ignited so late in the compression stroke it may still be burning as the exhaust valve opens. Bad for the valve.

And the ECU appears, from what I have seen, to run even richer than normal if lots of preignition is heard. This leads to carbon buildup in the combustion chambers.
 
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So if i run good gas all the time then i dont have to worry about detonation ....right? I can run 22psi or what , just tryin to get the most out of the car it doesnt get driven that much, im having alot more fun now that i got the dp mm...... i just want more boost now that i can get it but dont want to break the turbos till im ready to go single.... thanxKevin.. good gas meaning 104 up...
 

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Kevin Hornsby said:
So if i run good gas all the time then i dont have to worry about detonation ....right? I can run 22psi or what , just tryin to get the most out of the car it doesnt get driven that much, im having alot more fun now that i got the dp mm...... i just want more boost now that i can get it but dont want to break the turbos till im ready to go single.... thanxKevin.. good gas meaning 104 up...
If you run 100+ octane all the time (I do) then you can boost the hell out of it, all you're likely to do is spin the turbos into the grave earlier than they might otherwise have gone. They may still last 10's of 1000's of miles though. It is a crapshoot.

Have fun!
 

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I have 89 K on my stock twins....i have owned car 3 years....bought it with 48K I have run high boost and pulled hose for that entire time. No failures hitting 1.3-1.5 bar going down the 1/4 a billion times.....and on roll ons and street racing hit 1.5-2.0 bar (4th and 5th gear). I have no problems yet.....and if i do....i am not disappointed because they have lasted 90K. Becasue my luck, probably after i post this i will have problems..lol Everyone makes it seem like if you go over 18psi...the turbos will blow soon after......Granted some have blown quick..and others like mine have lasted a long long time run hard, but most i think will be fine boosting high. I tend to believe changing oil often and general maintenence has proven ( at least for me) to prolong life. Or luck, or BAD previous owners are the cause. And i don't even own a turbo timer..lol But i always let my car cool down...and never hit boost until car is warmed up though. Just my .02
 
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Silver Bullet said:
I have 89 K on my stock twins....i have owned car 3 years....bought it with 48K I have run high boost and pulled hose for that entire time. No failures hitting 1.3-1.5 bar going down the 1/4 a billion times.....and on roll ons and street racing hit 1.5-2.0 bar (4th and 5th gear). I have no problems yet.....and if i do....i am not disappointed because they have lasted 90K. Becasue my luck, probably after i post this i will have problems..lol Everyone makes it seem like if you go over 18psi...the turbos will blow soon after......Granted some have blown quick..and others like mine have lasted a long long time run hard, but most i think will be fine boosting high. I tend to believe changing oil often and general maintenence has proven ( at least for me) to prolong life. Or luck, or BAD previous owners are the cause. And i don't even own a turbo timer..lol But i always let my car cool down...and never hit boost until car is warmed up though. Just my .02
Sounds like advice everyone should follow
 

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my friend has over 150k miles on his STOCK turbos, and they still are hittin hard, im not sure how long he was bpu, but i kno that tender loving care with the occasional oil change and turbo timing, your turbos will last a very long time....
 
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