Lindsey Boost Enhancer setting for stock Turbo S
07-28-2009, 05:16 PM
#1
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Lindsey Boost Enhancer setting for stock Turbo S
Hi All,
I've finally purchased my first 944! It's an 88 Turbo S in great shape with no performance mods. The boost is amazing when it kicks in, and at this point I don't really feel the need to change the chips or increase the stock max boost pressure. I would however like to decrease the spool time and achieve a bit more boost at lower RPM. For this, it looks like the best option might be a simple ball and spring controller that can prevent the wastegate from opening until a preset amount of pressure is achieved. I've been reading a bit about the Lindsey Boost enhancer and am trying to determine what would be the appropriate setting for a turbo S with stock chips, wastegate etc... I've read that the stock max boost pressure on these cars should be no higher than ~12 psi (0.85 bar). Is this right? Has anyone had experience measuring this first hand or is this value more based on readings from the stock gauge? I know the LBE comes with a "factory setting" of 10 psi, but considering that they recommend a setting 5 psi below your max, I think this would be too high for use with the stock chips and could lead to over-boost problems if the wastegate cannot open in time to bleed off pressure before max boost is achieved. What do you think about running it at more like 7-8 psi? I guess the answer depends on what the actual stock chip boost limit is before the over-boost protection kicks in. Any thoughts on this? Thanks for your help!
K
I've finally purchased my first 944! It's an 88 Turbo S in great shape with no performance mods. The boost is amazing when it kicks in, and at this point I don't really feel the need to change the chips or increase the stock max boost pressure. I would however like to decrease the spool time and achieve a bit more boost at lower RPM. For this, it looks like the best option might be a simple ball and spring controller that can prevent the wastegate from opening until a preset amount of pressure is achieved. I've been reading a bit about the Lindsey Boost enhancer and am trying to determine what would be the appropriate setting for a turbo S with stock chips, wastegate etc... I've read that the stock max boost pressure on these cars should be no higher than ~12 psi (0.85 bar). Is this right? Has anyone had experience measuring this first hand or is this value more based on readings from the stock gauge? I know the LBE comes with a "factory setting" of 10 psi, but considering that they recommend a setting 5 psi below your max, I think this would be too high for use with the stock chips and could lead to over-boost problems if the wastegate cannot open in time to bleed off pressure before max boost is achieved. What do you think about running it at more like 7-8 psi? I guess the answer depends on what the actual stock chip boost limit is before the over-boost protection kicks in. Any thoughts on this? Thanks for your help!
K
07-28-2009, 05:37 PM
#2
Three Wheelin'
Anytime you start messing with boost, you should put an aftermarket gauge in. They are easy to install (they need 12v switched and you can run a vacuum line to the intake) and much more accurate than the one in the dash.
Yes, stock boost is ~12PSI. If you want to exceed that at all you should chip your car (ie; the LBE kit comes with a 944MAX chip as well as the boost enhancer).
When you chip your car you effectively override the built in boost protection and can safely boost higher (usually up to 15PSI) with no additional modifications.
A really nice upgrade however would be something like a Tial wastegate with a manual boost controller (you'd no longer need the LBE but you would want to chip your car).
I had a LBE with the 944MAX chips but there was a VERY noticeable performance improvement when I went to a Vitesse AFM chip and replaced the stock WG with a Tial 38mm.
I had no idea how much of an improvement the Tial would be. I can floor it in 3rd and 4th gear and it just hangs on to 15PSI all the way to nearly 6k RPM - that was definitely not possible with the stock WG. I don't think there was really anything 'wrong' with mine other than it was old and tired and started to leak/open at 8ish PSI so there was significant falloff at the higher RPM's. It just wouldn't hang on to boost long enough.
If you want to go with a ball/spring I'd recommend the Accuboost w/ ceramic ball. This device goes in between the intercooler banjo and the wastegate so you effectively can bypass your cycling valve (what your LBE is hooked up to now). You'd definitely want to chip your car though if you go that route.
There's a lot of folks on here that have had a great experience with the 944MAX chips, personally though I prefer the Vitesse AFM chip.
A relatively cheap and easy upgrade is replacing your stock BOV with one of the aluminum aftermarket ones (you can get them at Lindsey - I use their EVO). The stock unit is a POS and in a 20+ year old car it's something that's definitely worth replacing. It will take you 10 minutes to swap that thing out.
Good luck!
Yes, stock boost is ~12PSI. If you want to exceed that at all you should chip your car (ie; the LBE kit comes with a 944MAX chip as well as the boost enhancer).
When you chip your car you effectively override the built in boost protection and can safely boost higher (usually up to 15PSI) with no additional modifications.
A really nice upgrade however would be something like a Tial wastegate with a manual boost controller (you'd no longer need the LBE but you would want to chip your car).
I had a LBE with the 944MAX chips but there was a VERY noticeable performance improvement when I went to a Vitesse AFM chip and replaced the stock WG with a Tial 38mm.
I had no idea how much of an improvement the Tial would be. I can floor it in 3rd and 4th gear and it just hangs on to 15PSI all the way to nearly 6k RPM - that was definitely not possible with the stock WG. I don't think there was really anything 'wrong' with mine other than it was old and tired and started to leak/open at 8ish PSI so there was significant falloff at the higher RPM's. It just wouldn't hang on to boost long enough.
If you want to go with a ball/spring I'd recommend the Accuboost w/ ceramic ball. This device goes in between the intercooler banjo and the wastegate so you effectively can bypass your cycling valve (what your LBE is hooked up to now). You'd definitely want to chip your car though if you go that route.
There's a lot of folks on here that have had a great experience with the 944MAX chips, personally though I prefer the Vitesse AFM chip.
A relatively cheap and easy upgrade is replacing your stock BOV with one of the aluminum aftermarket ones (you can get them at Lindsey - I use their EVO). The stock unit is a POS and in a 20+ year old car it's something that's definitely worth replacing. It will take you 10 minutes to swap that thing out.
Good luck!
07-28-2009, 06:35 PM
#3
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Thanks so much for the advice! I think the high RPM boost drop off you experienced may be characteristic of normal operation for the stock M 44.51 chip and/or K26#6 turbocharger. The 944 Workshop Manual states: "Maximum boost pressure of 1.75 +/-10% bar (absolute value) is reached at approx. 3,000 rpm. At higher engine speeds (engine typ M 44.51) the boost pressure drops again and reaches a boost pressure of 1.52+/- 0.03 bar (absolute value) at 5,800 rpm. With engine type M 44.52, the boost pressure remains constant at 5,800 rpm (1.75 bar absolute value) and drops only after this value has been passed." As described, my turbo S (M 44.52) seems to hold boost until close to 6000 rpm, but I've also heard that the K26#8 takes longer to spool (has more turbo lag) than the K26#6. This is another reason I was thinking that the LBE or similar boost enhancer might be a good option for the the turbo S. I'll have to go out and check, but I don't remember hitting max boost as low as 3000 rpm. If the LBE could help drop this to somewhere between 2-3K I think I'd be satisfied. For now anyway 
07-29-2009, 04:26 PM
#4
Instructor
I have been using the lindsey boost enhancer for 5 years on my 89 951, and I have not had any problems with the original setting on it, I have never adjusted it. In your situation, I wouldn't make any adjustments without actually calling Dave or Mike Lindsey.
