Question about chips, gas, KR, and boost.


New Member
Well, I finally got my Scanmaster 2.1 today, and installed it the first thing when I got home. Now I have some questions concerning boost levels, chips, and gas.

To start with, my bird has these pertinent mods at the moment...
Hotwired fuel pump
Adjustable fuel regulator @ 46psi
K&N filter
Removed turbo sucker / installed breather
Adjustable wastegate actuator
Thrasher 92 chip

My question concerns gas, boost, and chips. I usually run a mix of 100 octane race gas and 92 pump gas in the car (for the detergents.) I usually run a ratio around 70% race gas / 30% pump gas.

After installing the Scanmaster tonight I made several runs. Outside air temps were about 88-90 degrees F (gotta love California nights). I was running 18.5 psi boost. I got O2 numbers in the .760-.780 range each pass, and I'm getting the big double 0's on the scanmaster for knock retard. This of course made me think... "MORE BOOST!"

However, when I got home to tighten up the wastegate actuator rod, I got to thinking rather than going to more boost with the Thrasher 92 chip, the car might be faster on with a Thrasher 100 chip and a similar boost level.

Any comments from people who have had similar situations? Should I raise the boost on the 92 chip until I start seeing a little bit of KR, or should I grab a Thrasher 100 chip and give that a go? I plan on running the 100/92 octane combo as long as I have the car if that influences your recommendations. I also have an RJC PowerPlate on order and will be picking up a THDP in about a month, so take that into account when you recommend options.

I've only been in the LC2 crowd a little over a month now so I'd appreciate any advice from you experienced experts.


Obsession or Digression?
Sounds like you are headed in the right direction with the mods. I would try the 100 chip to see how it works, just get out of it if the SM shows a kr number over a few degrees, especially in boost higher than 18 psi. I'm just learning about the timing and fueling, but the 100 chip is probably around 4* to 6* more than the 92 and would have more fuel in WOT conditions, so you could run more boost with the higher octane.

My results showed knock with slightly higher octane until I increased the timing and especially the fuel at WOT. That is how I am learning to tune my car with the Trans +. It seems to be working with the results I have had lately. May need to run it for a time to know the results of the tune. That's what I am going to do soon. Here are a couple good threads about timing, fuel, and octane. You can see my mods in the first thread, they are similar to yours:


Venomous Snake Handler
No expert here, but boost makes more power than timing. And since the stock turbo doesn't do much after 23#'s +/- of boost, If you can get 20-22 #'s on a Thrasher 92 at around 97 octane and no KR, then throw in some timing. Hopefully your getting the THDP w/ dump or straight pipe. Once you get the cat off, you'll only have it on once every two years :D


If your mixing 92 and 100 octane there is no reason you can't run 20-21psi with that chip. Your going to want to probably add a little more Fuel Pressure when you up the boost.

Your 02 numbers are pretty much where I like to run on the street but with more boost its going to go a little more lean. Just watch it.

Then back the boost off to 17psi and throw the other chip in there and bring it up 1psi at a time.

THose chips are very mild, you should be able to get away with 20psi on the 100 with a 100/92 mix.


New Member
I forgot to mention that... the car currently has a test pipe. the original cat is sitting in a box. My THDP will have a test pipe also, and yep, that cat will only be on the car every 2 years for a few days ;)

I think I'll probably pick up a Thrasher 100 chip, but I want to do some more experimenting with the 92 chip first.

As far as the adjustable wastegate actuator goes: shortening the rod raises boost, correct? How much typically do you have to thread it in to achieve a noticeable increase in boost? (Basically, if I thread it in 1 turn will I notice anything, or do I need to go more?) I'm aware each car is probably different, but usually how much do you have to shorten the rod to get a 1psi increase in boost?

I'm well aware I'll probably have to increase the fuel with boost... the 46psi seems to be right on the money with 18.5 psi. However, don't the stock injectors start having spray pattern issues around 47-48psi?

Thanks again for helping the new guy :p


I havent played with the stock actuator in a while but I belive it's about 1 pound of boost for every 1 turn tighter on the actuator.

Other than that I think Mike is pretty much on point with what the chip should let you do boost wise.



New Member
Yep... 1 turn = 1 more psi. I'm at 20psi now... still 0.0 on the KR even when it's pushing 90 outside :)

I think I'm going to try a Thrasher 100... should I go with the WOT TCC lockup? Russ is suggesting that I don't because my car sees 90% street use. Comments?

I think tomorrow I'll yank my intercooler and see what 2800 miles of oil film buildup looks like. Hopefully, not bad. The turbo sucker officially left the building Wednesday night, so I now it's time to flush it out.