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Discussion Starter #1 (Edited)
BPU feels ..... well slow. A single turbo has just been expidited on my list of things to have.

Nut shell t-66 to t-78 can someone explain in detail the two?
At what rpm's do they hit 500 HP?
At what point do they peak?
At what point to they even pull 300 HP?


Plus isn't a t-78 a turbo that can only hit 14psi as a minimum figure? So when I drive it in the street it will feel weak until the turbo activates at 4800 rpm. LIke a on and off switch?
 

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a t78 will hit about 500hp around 4500 rpms, which is when you get full boost. you can run it at lower then 14psi, you just have to get the softer, yellow wastegate spring.

the power does come on really fast with the t78, but there isnt really a period were u can sit there and drink a pop while its spooling. it still feels pretty strong even when its building boost. but full boost comes on pretty violently, it hits really hard and fast. i love it:D
 

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Discussion Starter #3
shit I've been looking around at web sites and I am sold... t-78. What kinda spring do you have? So at 14psi at 4800 rpm your pushing 500 HP? what do you get at 18psi-20psi? Or better yet say I do get that yellow spring and push 11psi what kinda HP will i be pushing? and if i do get that yellow spring can I still hit the max HP that a non yellow spring would give?
 

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I just found this thread...

Yes, t78 experts out there, if I get the yellow spring (whichever one that lets me run lower psi like 11), will it still be able to run the higher boost levels like Jesus and Angel were??? Like 24-28PSI, or do I have to get the 14PSI spring to hit those levels? Please help me as I am ready to make the purchase!! Thanks and peace!
 
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The wastegate spring determines the MINIMUM boost only. The boost controller will "leak" boost signal from getting to the wastegate, fooling it into thinking it's at a lower boost level than it is. So theorhetically, you could keep boost till the engine, wastegate, turbo blows up. The spring only prevents you from running say 10 psi.
 
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You will still be able to turn it up...but as a general rule of thumb, you can only go about twice wg pressure. So if you had a 10 psi spring-20 psi would be the upper limit. This is not set in stone, but as you lower your low boost, you also lower your high boost. With that being said, I have run 35 psi on my T78 on the street with my 14 psi spring :) And have run 32ish while messing around with my temp T88.

And it was fun.
 

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So...

I could put in the smaller spring so that my lower boost setting is more controllable on the street, but I could still in fact run 28 PSI and maintain it without a problem, given everything else is up to par?? Thanks!
 

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Sorry Angel....lol....

You posted your response as I was typing mine...lol...would you by any chance ever have dynoed your car at minimum boost (14 PSI) and if so, what numbers did you lay down?? Have you driven it like that on the street with DRs and did it hold?? Thanks!
 
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35 psi with a T-78.....:drooling:
Damn, I gotta ride in a single turbo Supra. Anyone have a single turbo Supra near San Antonio that would let me ride in like a 30-140mph highway run? PLEEEAAAASSSSSSSEEEEEEEEE:D
 
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Re: Sorry Angel....lol....

n disgii said:
You posted your response as I was typing mine...lol...would you by any chance ever have dynoed your car at minimum boost (14 PSI) and if so, what numbers did you lay down?? Have you driven it like that on the street with DRs and did it hold?? Thanks!


I have never really tuned for it, but I have done some baselines before going on to higher boost and it always makes more than 500 rwhp at 14 psi (my wg settiing) and I think it has made as much as 540 or so....that was on stock cams, should be better now.
 
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Sorry, to answer the second part of your question, yes with a WARM drag radial it will usually hold just fine from a roll or on a mild "launch" at that boost level.
 

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cool...

It looks like I'm just gonna keep the 14PSI spring that it comes with in it and let the AEM Stand Alone(Traction Control and Boost vs Speed) control the traction down low. Thanks much for the info! Peace!
 
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