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Discussion Starter #1
I have an '03 CC D/A LB with a Hot Juice, stock exhaust, K&N filter with homemade 4" PCV intake from stock filter box to turbo, stock Allison, approx 12K miles.


Regular mode on the Allison is set to level 3, T/H mode set to level 4. Have EGT and Boost guages, wastegate signal is currently blocked off.


When in T/H mode, I see appprox 31-32 psi in 2-4th gear and from 1250-1350* F EGT, but going into 5th it makes slightly less boost and EGT backs down as low as 1000* F. The Allison has never been limped. I assume it's defueling slightly, but why? Is it just something the HJ does, or is the HJ detecting slippage?
 

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Discussion Starter #2
Also, what EGT's and boost pressures do others see? What set-up are you using?


I welcome all comments, good or bad.
 

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I'm assuming your questioning the EGT Boost values droping right after the shift ...






If so, it is simply less load on the engine in overdrive after the shift .... Find a hill she'll climb right back up in overdrive....


Your readings seem in line ... Wastegate deprived huh !!!!





Mac
 

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Discussion Starter #4
Yes, but I thought they (EGT and boost) would climb back up once the shift to 5th was made. They do come back up somewhat, but not much at all.


The wastegate signal is blocked off, but I've tried messing with a few different things. I used a valve to restrict flow, but found totally blocking it off will still only give 32 psi max with the HJ on level 4. With the signal connected and un-restricted I see maybe 25-26 psi.
 

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There have been a couple of people that have cooked the turbo with the wastegate disconnected. I would not think that it would be worth the 10-20 hp that it may allow.





Jess
 

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Discussion Starter #6
Really? That's the first I'd heard of anyone hurting the turbo because of that . Anyone from here?
 

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Greg from Ft. Collins. His handle is Deezul Smoke or something like that.


Jess
 

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Discussion Starter #9
http://dieselplace.com/forum/forum_posts.asp?TID=1256&KW=turbo+wastegate+





http://dieselplace.com/forum/forum_posts.asp?TID=643&KW=turbo+wastegate+





http://dieselplace.com/forum/forum_posts.asp?TID=612&KW=turbo+wastegate+
 

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I think it has to do with the drop in RPM as there is a correlation between RPM and boost. If I'm right then when the RPM get's back to where it was in 4th then your boost and EGT should be back as well.
 

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I have, I would not reccomend plugging the wastegate, do you know how much a new trubo is, installed? Not cheap!
 

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From what I've heard anything over 30 psi boost your not really gaining much. Heard of several cases of turbos going out at 36-40psi range. As far as EGT I am running the tst powermax 1300-1400 with 30 psi boost in 5th gear not uncommon. You will slip the stock transmission though. I have been told by tst if you run the stock waistegate tube instead of the foiler they supply the boost will increase but they strongly recomend keeeping boost under 30 psi though.
Jon
03' allison ext cab 4wd stage II intake 4" exhaust w/6" tip:-D transgo and tripple lock TC waiting to get TST Comp it's on order:-D
 

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Look up the compressor maps for this turbo. They are going to be running out of air much over 35 psi. There is not enough power to be gained by raising the boost 5-10 psi. You may gain 20 hp, but you will also increase back pressure in the exhaust side of the turbo, increase EGT, and so on. If you are looking for more hp, then a higher hp tuning box is the way to go.


Jess
 

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Discussion Starter #14
I don't think I gained any power (the same amount of fuel is being injected regardless of boost pressure), but I did experience a very slight drop in EGT. In any case, I am at the limit as far as what the turbo can handle, so any increase in boost psi would not be a good idea. I think what I'm going to do is alter the wastegate signal instead of totally blocking it so I get 26-28 psi instead of the 30-32 psi I'm seeing currently. I still have to post pics of my homemade air intake. I'll try to post some in a minute....
 
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