Boost Actuator Adjustment Pays Off
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Senior Member
Joined: Jun 2000
Posts: 648
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From: Milford, Ohio USA
Boost Actuator Adjustment Pays Off
Gang:
I've been reading the threads concerning adjustment of the boost actuator. It seemed promising, although nobody had really posted any sort of concrete results. Anyway, I worked on it Thursday night and got it adjusted to what I would consider "ideal". What this translates to is "just as greedy as I can get without building boost at a steady 80 MPH cruise". Mechanically, this involved raising the assembly until the lever JUST touched the stop, then lowering it a "smidgen" (perhaps 2 or 3 mm).
With it thus adjusted, the boost comes on MUCH faster, and with considerably less provocation. This actually makes the beast much more fun to drive, as at highway speeds you're never more than a "gnat's eyelash" away from full boost (a slight twitch of the pedal is al it takes). Also, you can get decent boost (5 or 6 PSI) on a half-throttle pull from 20 mph on up (much more "gutsy" under "normal driving conditions"). Basically, any time you put load on the engine, you've got good strong boost. This also makes for better smoke shows, as the boost hits quicker and harder form a dead stop pedal-mash. Finally, I'm also seeing an extra half-pound of boost or so under certain conditions (can't really explain that one, but others have reported it also).
The "fun factor" alone would have made the adjustment worthwhile, but as a bonus I also saw good results at the track. I ran three passes Saturday at Tri-State Dragway. I was very careful with my cool-down and staging routine in an effort to keep the experiment as "clean" as possible. For reference, I'll compare results to me previous outing (Edgewater Dragway last November). For the November outing, the humidity and barometric pressure were comparable, but the air temperature was between 10 and 12 degrees cooler than it was Saturday. I made NO modifications since November, and only put another 200 or so miles on the truck. Everything else was the same (weight, fuel, and what-not). So basically, the conditions were IDENTICAL except for the boost actuator adjustment and 10 to 12 degrees of air temperature (WARMER on Saturday). General, qualitative "traction conditions" were comparable as far as I could tell.
Anyway, I ran on average better 60-foot times Saturday compared to November, despite the 10-degree temperature difference (incrementally less power potential). I cut 0.02 seconds off my "career best". I attribute this stromgly to the more immediate boost, which pulled the 'Bolt out of the hole with more authority. I also ran faster eighth-mile times, on average, than I had run in November (despite the higher air temperature and correspondingly less power potential). Again, I cut about 0.02 seconds off my "career best". The warmer weather slowed me a little by the quarter-mile mark, although I consistently (back-to back runs) posted times that were within 0.02 to 0.05 seconds of my "career best". I was down about 0.5 mph through the quarter-mile trap due to the warmer air.
I should also mention that the "career best" times for 60-foot, eighth-mile, quarter-mile, and trap speed were all set on a single run. For that run, I had a bit better cool-down than any of the runs Saturday, pushed the bloated thing through the staging lanes (that hurt!), and was enjoying air temperatures that were solidly 12 degrees cooler than Saturday.
Analyzing all of this, I have to say that I picked up between 0.05 and 0.10 seconds in the quarter from the actuator adjustment (correcting all of the times for conditions and cool-down regimen). This is a direct result of the more immediate boost and possibly higher ultimate boost pressure. There are REAL gains to be had by carefully adjusting the actuator.
Now, in the essence of "balanced coverage", I have to report that there is a real down-side to the adjustment. For one, I did note noticeably higher heat build-up in the blower/intercooler circuit (on the boost more often, higher boost on average - particularly at lighter load). This isn't too much of a worry to me, but worth mentioning. The big down-side I noted happened on my last pass of the day. I gave the motor a good cool-down (90 minutes or so) and went out right at closing time in an attempt to rip off an all-time best. I felt that I had real potential, as I was very close on the first two passes. This would have really "sealed the deal" on the the value of the actuator adjustment. Anyway, I had launched from idle on the first two passes, and realized that I was going to have to do something different to speed up to any degree (steady air and track conditions all day). For the last pass, I went with a power-braked launch at a modest 1500 RPM. I've never had any trouble with power-braking the launch before, even up to 2200 RPM or so. Anyway, much to my shock, the thing launched at full boost (due to the adjustment) and simply blew the tires off all the way through first gear. I ran a 2.267 60-foot and a correspondingly crappy 14.271 elapsed time at 97.816 MPH. It never would have roasted the tires like that on a low-RPM power-braked launch before the actuator adjustment.
On a positive note, I "won" all three "races" on the day. Beat a tubbed Pinto drag car, a new WS6 Trans Am (went up in smoke), and a built Mustang on a holeshot.
Let me know what you think of my analysis of the boost actuator adjustment. I'm absolutely convinced that I picked up some time at the 'strip, and it's a lot more fun to drive on the street.
------------------
Silver Y2K Lightning
Bone Stock w/ Duraliner, Ford Hitch Cover
Best 60-foot: 2.041
Best 1/8: 8.872
Best 1/4: 13.789
Best MPH: 99.67
Silver (matching) Y2K ML320 Benz
Burl (ML430) Shift ****
Best Run: 17.137@80.629 (2.550 60-foot)
1992 Grand Prix SE
Commuter Mule, G-Tech 17.3 @ 81
I've been reading the threads concerning adjustment of the boost actuator. It seemed promising, although nobody had really posted any sort of concrete results. Anyway, I worked on it Thursday night and got it adjusted to what I would consider "ideal". What this translates to is "just as greedy as I can get without building boost at a steady 80 MPH cruise". Mechanically, this involved raising the assembly until the lever JUST touched the stop, then lowering it a "smidgen" (perhaps 2 or 3 mm).
With it thus adjusted, the boost comes on MUCH faster, and with considerably less provocation. This actually makes the beast much more fun to drive, as at highway speeds you're never more than a "gnat's eyelash" away from full boost (a slight twitch of the pedal is al it takes). Also, you can get decent boost (5 or 6 PSI) on a half-throttle pull from 20 mph on up (much more "gutsy" under "normal driving conditions"). Basically, any time you put load on the engine, you've got good strong boost. This also makes for better smoke shows, as the boost hits quicker and harder form a dead stop pedal-mash. Finally, I'm also seeing an extra half-pound of boost or so under certain conditions (can't really explain that one, but others have reported it also).
The "fun factor" alone would have made the adjustment worthwhile, but as a bonus I also saw good results at the track. I ran three passes Saturday at Tri-State Dragway. I was very careful with my cool-down and staging routine in an effort to keep the experiment as "clean" as possible. For reference, I'll compare results to me previous outing (Edgewater Dragway last November). For the November outing, the humidity and barometric pressure were comparable, but the air temperature was between 10 and 12 degrees cooler than it was Saturday. I made NO modifications since November, and only put another 200 or so miles on the truck. Everything else was the same (weight, fuel, and what-not). So basically, the conditions were IDENTICAL except for the boost actuator adjustment and 10 to 12 degrees of air temperature (WARMER on Saturday). General, qualitative "traction conditions" were comparable as far as I could tell.
Anyway, I ran on average better 60-foot times Saturday compared to November, despite the 10-degree temperature difference (incrementally less power potential). I cut 0.02 seconds off my "career best". I attribute this stromgly to the more immediate boost, which pulled the 'Bolt out of the hole with more authority. I also ran faster eighth-mile times, on average, than I had run in November (despite the higher air temperature and correspondingly less power potential). Again, I cut about 0.02 seconds off my "career best". The warmer weather slowed me a little by the quarter-mile mark, although I consistently (back-to back runs) posted times that were within 0.02 to 0.05 seconds of my "career best". I was down about 0.5 mph through the quarter-mile trap due to the warmer air.
I should also mention that the "career best" times for 60-foot, eighth-mile, quarter-mile, and trap speed were all set on a single run. For that run, I had a bit better cool-down than any of the runs Saturday, pushed the bloated thing through the staging lanes (that hurt!), and was enjoying air temperatures that were solidly 12 degrees cooler than Saturday.
Analyzing all of this, I have to say that I picked up between 0.05 and 0.10 seconds in the quarter from the actuator adjustment (correcting all of the times for conditions and cool-down regimen). This is a direct result of the more immediate boost and possibly higher ultimate boost pressure. There are REAL gains to be had by carefully adjusting the actuator.
Now, in the essence of "balanced coverage", I have to report that there is a real down-side to the adjustment. For one, I did note noticeably higher heat build-up in the blower/intercooler circuit (on the boost more often, higher boost on average - particularly at lighter load). This isn't too much of a worry to me, but worth mentioning. The big down-side I noted happened on my last pass of the day. I gave the motor a good cool-down (90 minutes or so) and went out right at closing time in an attempt to rip off an all-time best. I felt that I had real potential, as I was very close on the first two passes. This would have really "sealed the deal" on the the value of the actuator adjustment. Anyway, I had launched from idle on the first two passes, and realized that I was going to have to do something different to speed up to any degree (steady air and track conditions all day). For the last pass, I went with a power-braked launch at a modest 1500 RPM. I've never had any trouble with power-braking the launch before, even up to 2200 RPM or so. Anyway, much to my shock, the thing launched at full boost (due to the adjustment) and simply blew the tires off all the way through first gear. I ran a 2.267 60-foot and a correspondingly crappy 14.271 elapsed time at 97.816 MPH. It never would have roasted the tires like that on a low-RPM power-braked launch before the actuator adjustment.
On a positive note, I "won" all three "races" on the day. Beat a tubbed Pinto drag car, a new WS6 Trans Am (went up in smoke), and a built Mustang on a holeshot.
Let me know what you think of my analysis of the boost actuator adjustment. I'm absolutely convinced that I picked up some time at the 'strip, and it's a lot more fun to drive on the street.
------------------
Silver Y2K Lightning
Bone Stock w/ Duraliner, Ford Hitch Cover
Best 60-foot: 2.041
Best 1/8: 8.872
Best 1/4: 13.789
Best MPH: 99.67
Silver (matching) Y2K ML320 Benz
Burl (ML430) Shift ****
Best Run: 17.137@80.629 (2.550 60-foot)
1992 Grand Prix SE
Commuter Mule, G-Tech 17.3 @ 81
Senior Member
Joined: Mar 2000
Posts: 938
Likes: 0
Silver-Y2K-SVT,
I have also adjusted my boost actuator with good results. Although I have not been to the track to really test however I know the "seat-of-pants" meter says boost comes on much faster along with tire wear and I cheat some and look at my guage. I have an external Auto Meter boost guage and 10 lbs. of boost is common.
I went real extreme with the adjustment and deceided to back off a little more. My concern was being in boost at highway speeds, 70 - 75 MPH.
No doubt this is a cheap mod that works.
------------------
John Armstrong
2000 Red Lightning
#444 of 4966
Born 2/22/2000
Went home 3/6/2000
[This message has been edited by jarmstro (edited 04-30-2001).]
I have also adjusted my boost actuator with good results. Although I have not been to the track to really test however I know the "seat-of-pants" meter says boost comes on much faster along with tire wear and I cheat some and look at my guage. I have an external Auto Meter boost guage and 10 lbs. of boost is common.
I went real extreme with the adjustment and deceided to back off a little more. My concern was being in boost at highway speeds, 70 - 75 MPH.
No doubt this is a cheap mod that works.
------------------
John Armstrong
2000 Red Lightning
#444 of 4966
Born 2/22/2000
Went home 3/6/2000
[This message has been edited by jarmstro (edited 04-30-2001).]