The Budget Bomber - Part 2

[100 Proof]

This is a follow-up to a thread I started here. on May 1st here. I recently added a TAG and have been anxious to see how it affects my numbers on the course I described in the original thread. I tried very hard to duplicate the run as closely as possible to the previous runs in order to generate useful and hopefully, objective data.



Here are my results to date:



Zero mods: Max EGT 1142°F, Max Boost 23. 6 PSI, AVG MPG 11. 1, AMB Temp 80°F.

Airbox mod: Max EGT 1135°F, Max Boost 23. 9 PSI, AVG MPG 11. 3, AMB Temp 80°F.

Airbox+TAG: Max EGT 1124°F, Max Boost 23. 2 PSI, AVG MPG 11. 2, AMB Temp 68°F.



Conclusion: As before, I'm not convinced that with a sample size of 1 test, that any of these numbers are statistically significant. The 11° reduction in EGTs between this mod and the Airbox mod was likely due to the 12° difference in ambient temperature between the runs. The MPGs are essentially unchanged by either the Airbox or TAG.



The one interesting difference was the boost reduction. Dropping boost by 3% with no noticeable change in power has got to mean something, but I don’t yet know how to interpret that. Perhaps others have some ideas?



I did not go into this with any pre-conceived ideas. I have collected data and presented it. I know others have reported different results.



For now, I'll keep it in. I MAY remove it later to see if I notice it when it is gone, as other members have reported. Frankly, I noticed no power or drivability differences after installation in my truck.



As I mentioned in the earlier post, I am contemplating some other low cost BOMBs, such as a PG7 drop in and a Donaldson or Nelsen muffler upgrade, just to see what they do. If/when I do these mods, I'll test the combo on the same run with conditions as similar as possible and post the results. I hope others will find this interesting and helpful.



100 Proof

 

[Fireman]

100 Proof



What air box mods do you have? I have a Scotty RA III and saw a significant decrease in EGT. As for the TAG there is one area where I have found that it makes a real difference. Towing heavy without the TAG, on long hills as the speed fell off and the RPMs dropped the boost would start falling off also. With the TAG under the same conditions the boost remained at 23 psi. I will admit for the most part the difference the TAG makes is very subtile and difficult to quantify.



my$. 02

Fireman

 

[100 Proof]

My Airbox mod consists of a 4" hole in the bottom the stock box and the addition of a 4", 90 degree street elbow. When pulling my trailer, I have a combined weight of 16,400 pounds. By down shifting into 5th, I am able to maintain speed on 6%+ grades, so I do not see the RPM decrease that you do.



Frankly, I've always been happy with performance of this truck. I'm just having fun seeing what some of these "passive" and inexpensive changes do. I see lots of dyno data posted. What I'm trying to do is post data about road and towing performance that is collected in a repeatable, consistent way to do comparisons of the changes I make.



Do you have some good data collected on the RA III temperature decrease? I'd be interested in seeing some before/after data collected in a repeatable way.



100 Proof

 

[Fireman]

No doubt about it, stock performance isn't bad. I got the Scotty before gauges, so I don't have good data on that. What I can tell you is towing 20,000# gcw with the scotty alone the max EGT seen was 1100 deg. With the addition of a 4" exhaust max EGT 1050 deg.



I can maintain speed by down shifting on the hills also. The point I was making was when running in 6th gear on a hill when the speed and RPMs dropped the boost will not with the TAG. It tells me that it DOES improve airflow, however I have seen no real change in mileage or EGT attrituable to the TAG. With my analog gauges (and old eyes) the best I can say about the boost is 23 psi max. I can't discern tenths



Max EGTs are up about 100 deg since the addition of a VA, and I don't have to downshift on the hills any moreOo.



Fireman

 

[dozerdogue]

Maybe the reduce in boost is due to the fact that the tag is restricting air into the compressor housing. the only way to truly know wether you gained or lost any power is to dyno it. I think it's quite impossible to feel any loss or gain of 1/2 lb difference by useing your seat of the pants dyno.