First ride on the new turbo in the mountains. Questions?????

[Rx1M5]

Ok finally got out on the new turbo in the mountains today and all in all it ran pretty darn good. I won't go into rants about the power as I'm sure you've all heard it before but holy crap does this thing rip and I don't even have it turned up yet. Here's what happened today.

1st off I haven't got a fuel pressure gauge yet so I don't have a clue what that is set at but I will get one and set it to about 5 lbs at idle. Correct?

Does the fuel pressure at idle affect WOT A/F ratios? I was seeing these numbers today:

- 4-7000 rpm 10-11 cruising on the trail
- 7-9000 rpm 14-15 and the odd higher value while climbing
- WOT climbing mid 13's dropped into the 12's one time the odd time it stayed up towards 14

I am jetted at 127.5 17.5 pilot needles stock (2.5?) riding at 6500 feet temps around freezing today 9 lbs boost. Using Parkers knock box I got I think it was 10 knock events over 3 pulls. Will hitting the rev limiter simulate a knock event?

I'm thinking I need to fatten the main jet but how many sizes I'm not sure. Will 130's bring my A/F's into the 11's at WOT or should I go larger and what is a good target for WOT A/F?

For that 7-9000 range should I change the needles?

I know these are a lot of disjointed questions.

Thanks in advance for any help.

Rx1M5

 

[Trxster]

Wow, seems to me like the AFR's are a bit inverted. I think you want to be seeing lean numbers down low (14), slightly lean at 6-7000rpm barely on the throttle (12-13), and not higher than around 12.3 at WOT. With lean numbers on the lower RPM's the engine will rev and build power a bit quicker (seat of the pants feeling) but you want it to richen up when you get into the throttle at all.

It seems like mine WOT readings only move about .3 or so per jet size but it seems that everyone's sled is a bit different (and it looks like you have a differnt turbo than most of the kits I've seen). I'd say if you probably want to step up 2 or 3 sizes on your main and drop you needle 1-2 clips for the mid.I just dropped mine jets to 122.5 and will still probably be around 11.8 or so but I believe in staying on the slightly rich side of things and there is more than enough power.

Regarding the fuel pressure, I think I was told by Dave @ Powderlites to run it around 3.5 if you are connecting the reg to the back side of the carbs. If you run it to the IC, then you want to run it around 5 I believe. Dave says that they run of the back side of the carbs and reduce pressure so that when you throttle chop the pressure drops really quickly due to the vacuum. I have not had my sled die at all after a climb.


Also, what is your helix set at? Probably want to be around 48' and yeah, Holy Crap they hit hard!!!

That's my $.02....someone please correct me if'n I'm wrong.

Rt

 

[Rx1M5]

.3 per jet size is what I was looking for. I have a set of 135's here with me so maybe I should try those? Where does the 12.3 number come from, is that just common knowledge or something calculated by a formula?.

Rx1M5

 

[Trxster]

It may be a little more or less but either way, as you start to turn up the boost your AFR will go leaner so I'd plan on shooting for around 11.6 or 11.7 at minimum boost and that way you could turn it up to 10 and it will be running around 12ish. Good luck.


Rt

 

[Rx1M5]

I've decided to try the 135's that I already have here. I guess the worst case scenario is they will be too fat. How do these sleds run fat with a turbo?

Rx1M5

 

[summitking]

sleds

What air fuel gauge are you guys running?

 

[Rx1M5]

NGK/NTK

 

[Trxster]

I've decided to try the 135's that I already have here. I guess the worst case scenario is they will be too fat. How do these sleds run fat with a turbo?

Rx1M5

They run fine as long as your in the 11 range. If you run so fat that your down in the lower 10's it will bog. They clean up a little bit as you go up towards 12.....kind of like how you feel exercising on a warm muggy day vs on a crisp, cool autumn day. Both work, but one you just feel and sound better.

Rt