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Overboosting

twyztid said:
He borrowed an ECU & 3-bar MAP sensor from a friend that has a TD Max Spool 17 tune. Said it pulled great with those parts installed and was at 18.5psi. I guess the question is... what is the max boost supposed to be on that Max Spool 17 tune?
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Mines been at 17.8-17.9 psi on decent wide open pulls, this will vary slightly depending on muffler used/ possible hardware configurations etc. Sounds like hes within range. Definetly not 2 psi over anyway
 

justinator said:
Mines been at 17.8-17.9 psi on decent wide open pulls, this will vary slightly depending on muffler used/ possible hardware configurations etc. Sounds like hes within range. Definetly not 2 psi over anyway
Click to expand...


I am being told by a guy that installs TD tunes here in Michigan that the Max Spool 17 tune should have a max boost of 17. I don't know what to believe now.
 
Hence the name "Max Spool 17.
Would that be measured in Canadian or American? LOL
I have several friends with TCats on PEFI Stage 3 with liquid-filled boost gages on their dash and they say they always see between 17 & 18. It can flash to more than that but it comes down into the 17-18 range.
 
twyztid said:
I am being told by a guy that installs TD tunes here in Michigan that the Max Spool 17 tune should have a max boost of 17. I don't know what to believe now.
Click to expand...
He's incorrect, even my max 16 flash saw over 17 with 3 bar and blow off valve upgrade. Im sure if you search and do some reading on this site youll see plenty of guys are in the 17's to lower 18's. The big question is when will he be switching over to turbo dynamics?:)
 
Turboflash said:
Hence the name "Max Spool 17.
Would that be measured in Canadian or American? LOL
I have several friends with TCats on PEFI Stage 3 with liquid-filled boost gages on their dash and they say they always see between 17 & 18. It can flash to more than that but it comes down into the 17-18 range.
Click to expand...

I would like to know how their engines are staying together on a PEFI Stage 3 tune running 17+ psi using a 2-bar MAP sensor (which is what PEFI writes these tunes for). The 2-bar MAP sensor can't read that high so it wouldn't be adding any more fuel above the boost pressure that it can read. I have read differing things but that the 2-bar sensor maxes out at somewhere between 15.6-16.9 psi. I just don't know where in the range the REAL number is. Regardless, it is dumb to write a tune that is anywhere near the limit of that stock 2-bar MAP sensor... let alone run it ABOVE that limit. I have no idea what PEFI was thinking.
 
justinator said:
He's incorrect, even my max 16 flash saw over 17 with 3 bar and blow off valve upgrade. Im sure if you search and do some reading on this site youll see plenty of guys are in the 17's to lower 18's. The big question is when will he be switching over to turbo dynamics?:)
Click to expand...

My guess is that it will be very soon. :)
 
twyztid said:
I would like to know how their engines are staying together on a PEFI Stage 3 tune running 17+ psi using a 2-bar MAP sensor (which is what PEFI writes these tunes for). The 2-bar MAP sensor can't read that high so it wouldn't be adding any more fuel above the boost pressure that it can read. I have read differing things but that the 2-bar sensor maxes out at somewhere between 15.6-16.9 psi. I just don't know where in the range the REAL number is. Regardless, it is dumb to write a tune that is anywhere near the limit of that stock 2-bar MAP sensor... let alone run it ABOVE that limit. I have no idea what PEFI was thinking.
Click to expand...
I don't know the answer to your questions. Sebastien Guay, the owner of PEFI, is most known for tuning high performance 4 cylinder 4 stroke European and Japanese sports cars. He also taught advanced EFI fuel injection classes at several universities including engines with turbos. No idea how he does what he does but from my circle of friends who run his Stage 3, they run flawless every day and have been bullet proof for at least 4 years now and many thousands of miles rode hard. Whatever the tune it, and how he accomplishes it on a 2-bar MAP sensor we'll never know but that tune just plain rocks on a 998.
 
Turboflash said:
I don't know the answer to your questions. Sebastien Guay, the owner of PEFI, is most known for tuning high performance 4 cylinder 4 stroke European and Japanese sports cars. He also taught advanced EFI fuel injection classes at several universities including engines with turbos. No idea how he does what he does but from my circle of friends who run his Stage 3, they run flawless every day and have been bullet proof for at least 4 years now and many thousands of miles rode hard. Whatever the tune it, and how he accomplishes it on a 2-bar MAP sensor we'll never know but that tune just plain rocks on a 998.
Click to expand...

...and a TD Max Spool 17 "rocks" even more. I've seen it with my own eyes.
 
twyztid said:
I am being told by a guy that installs TD tunes here in Michigan that the Max Spool 17 tune should have a max boost of 17. I don't know what to believe now.
Click to expand...
max 17 as 17lbs with 2bar sensor the max spool 17 need the 3bar and btw he needs to upgrade bov and charge tube and gap plugs at 020
 
Last edited:
Anybody asked TD about this, I have 270hpSS , hurricane and when I had the single tune he gave me three bar. Boost reads higher . It’s better to ask the vendor before you blow each other sleds up.
 
Crossfire12 said:
Anybody asked TD about this, I have 270hpSS , hurricane and when I had the single tune he gave me three bar. Boost reads higher . It’s better to ask the vendor before you blow each other sleds up.
Click to expand...

I agree
Go to the experts who build and test these tunes...will avoid major head ache$$$$
 
justinator said:
Mines been at 17.8-17.9 psi on decent wide open pulls, this will vary slightly depending on muffler used/ possible hardware configurations etc. Sounds like hes within range. Definetly not 2 psi over anyway
Click to expand...

How long of a wide open pull does it take for you to get to 17.8-17.9? Does yours slowly creep up?
 
yamahahaapex said:
How long of a wide open pull does it take for you to get to 17.8-17.9? Does yours slowly creep up?
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no it actually spikes a bit over that at first whack of the throttle and then stabilizes at 17.8-17.9 after holding it
 
This is what I use to read when I had the TD Max Spool 16 two bar tune, 15.9 - 16.1

I upgraded to the TD Max Spool 16 three bar tune, and my readings have been 16.9 - 17.3

I was told that the 2 bar tune was fine but could not properly read boost over a certain point, so it simply just added fuel for safety once at that point. Whereas the 3 bar tune could read higher boost level, and thus, did not need to add extra fuel at any point, it was a more refined tune. Power seemed much the same on either.

From what I saw, the 2 bar only allows your pod to read a bit over 16, while the 3 bar sensor allows at least into the 17s.
 
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