TT5.9mag
Two atmospheres are better than one
And how does that compare to wide open afr with 34 MABs?
Ultra XP850 Almost there!
- Thread starter Ironmike
- Start date
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tjpatte
Well-Known Member
Interested as well, let us know Mike, about to head down this path as well. Have gotten pretty close to where I want to be, but the results of your testing may get me all the way there.
TT5.9mag
Two atmospheres are better than one
I don’t look for air bleeds (or emulsion for that matter) to make distinct yes/no black/white type of changes. I look for trends in the afr trace. I’m hoping Mike also can identify trends, or more correctly changes to the trends in his afr trace with regards to the new MAB size.
tjpatte
Well-Known Member
The only thing I haven’t messed with on mine is the air bleeds and PVCR as I’ve been pretty happy with the profile over rpm’s. Only looking for about .5 leaner afr at cruise so may just mess with it and see what happens.
At a cruise on the T slots or on the booster?
If you list your tune up it’s pretty easy to see if you have the booster starting too soon. Then you get the booster adding fuel and the T slot adding fuel and if you are not at the top of the T slot it can be too much fuel.
Also, you can lower the top emulsion one hole or make the top emulsion .004 smaller and see what you get.
I try not to make emulsion changes until I think I have the MAB/jetting sorted out. Unless there are 4 or 5 emulsion holes open.
Then I change that before anything else.
tjpatte
Well-Known Member
Hi Tim, this is currently where I'm at. Need to get to Barona and run it with the 5303 headers and see where I'm at. Engine was dyno'd by Brain at IMM with the middle emulsion bleeds open, but I plugged them to help with cruise.
| Primary | |
| Main Jet | 75 |
| Idle Feed Restriction | 0.035 |
| Idle Air Bleed | 73 |
| High Speed Air Bleed | 33 |
| Squirter | 35 |
| Power Valve | 4.5 |
| PV Jet | 0.07 |
| Kill Bleed | 0.027 |
| Tslot Restrictor | 0.0635 |
| Emulsion Bleeds | |
| #1 | 0.027 |
| #2 | Blocked |
| #3 | 0.032 |
| Secondary | |
| Main Jet | 82 |
| Idle Feed Restriction | 0.035 |
| Idle Air Bleed | 73 |
| High Speed Air Bleed | 33 |
| Squirter | 35 |
| Power Valve | Blocked |
| PV Jet | Blocked |
| Kill Bleed | 0.027 |
| Tslot Restrictor | 0.0635 |
| Emulsion Bleeds | |
| #1 | 0.027 |
| #2 | Blocked |
| #3 | 0.032 |
TT5.9mag
Two atmospheres are better than one
Not knowing too much about your setup, only that you want to lower cruise afr a touch, personally I would focus on P main jet in this case. Seems your stagger is biased towards primary, especially if you haven’t drilled,tapped, and jetted the PVCR yet. Then probably drop the MAB a touch, add some fuel to the primary through the pvcr and you should be poopin in tall cotton.
tjpatte
Well-Known Member
Thanks. Probably should have added more info, but didn’t expect Tim and you to actually try and figure it out! Lol
It’s a 410 with ported Edelbrock heads and Victor 340. Cam is 251/258 @ 50, 110 separation and .556 lift with 1.6 rockers. Quickfuel 850HR so has replaceable PVCR jets and .07 jets in it currently. Makes 540HP and runs pretty good, just cruise is around 13.1 and trying to lean it out a little for the hell if it. Barona is only 14 miles away so fuel mileage isn’t that important.
I’ll give it a try and thanks again!
What’s your tire size and axle ratio? You may be right on the edge of starting the booster while you are still into the T slot too much.
As the throttle blade moves from the closed position to the top of the T slot, fuel flow from the T slot tapers off.
And as TT5.9 said above, if you are on the booster and it’s not on the booster too soon you can trim the primary main jet and clean it up.
tjpatte
Well-Known Member
I’m pretty sure I’m on the booster, can see it go rich on the O2 gauge. I’m running 4:10’s with 275/55/15 tires which are pretty close to around 26”.
You probably are on the booster.
Just because I’m curious how did you end up with .032 in the bottom emulsion hole?
I’m not home so I can’t run out and look at my notes but there have been some times where I’ve used just one emulsion.
IIRC it happens when I get the MAB sized small enough to get the booster starting when I want. In that case, again IIRC I couldn’t get enough jet out of it to clean up WOT so I plugged the bottom hole, and that cleaned it up.
I can say when you are tuning this stuff it’s much easier (and significantly faster although you can get down a rabbit hole if you aren’t careful) on an engine dyno.
Hopefully in a week and a half or so I’ll have an engine on the dyno and I can write better notes so I can refer back to them.
tjpatte
Well-Known Member
That’s what the bottom holes pin’d out to, production tolerance I guess?
At my son’s high school graduation ceremony so can’t look at my notes from my previous tinkering.
Know what you mean about the rabbit hole, did that a couple of years ago. Read through most of the stuff on race mgfuelsystems. Was a lot to digest, but good info. Got some drill bits and taps then went to work. I think one of the biggest improvements was relocating the IFR to the bottom of the well, then TSLOT restricters.
Ironmike
Well-Known Member
Oddly, it seems to have maybe leaned it up a bit. Really difficult to watch that gauge at WOT in a 3100 lb car with 600 ish HP. Like I said earlier, I got a glimpse approaching shift light(6800), of 13.0 to 1. Like to see 12.5 or so. Might open up the factory secondary PVRC to .077.
Although...... I still have to try the .026 MAB's first. Need to pick up another half point or so at cruise RPM.
I'm soooo close to where I want.
TT5.9mag
Two atmospheres are better than one
That is odd if it did lean it up, but I agree glancing at the gauge while trying to drive, it’s very hard to identify more than just a number that flashes on the screen. Get a go pro and film the gauge. That’s my redneck data logger.
Ironmike
Well-Known Member
My redneck data logger is usually my nephew, who I usually scare the **** out of. He's one of those import geeks with a WRX. Nice thing is, he has a Draggy.
l might have missed it but I didn't see where you posted the results from your testing on the dyno on how the main air bleed size affects the rpm that the boosters start flowing fuel.
Ironmike
Well-Known Member
Last update. Maybe. Today I tried the 26 MAB's and I think it's about the same as 30's. 90 degrees and muggy as hell, so kinda hard to compare. However, I think it may have got a touch richer at cruise. Definitely richer up top, which is good. I don't think cruising around at 13.5 to 1 is great, but running out of options.
Hope Newbomb chimes in here...........maybe it's time to play with all those damn emulsions. Or maybe I should tighten up my T slot restrictors from .062 to .055?
today i can absolutely say it felt a bit "snappier" just off idle..................
Alas, still not perfect.
Hope Newbomb chimes in here...........maybe it's time to play with all those damn emulsions. Or maybe I should tighten up my T slot restrictors from .062 to .055?
today i can absolutely say it felt a bit "snappier" just off idle..................
Alas, still not perfect.
TT5.9mag
Two atmospheres are better than one
I think newbomb has been canned which is absolute bullshit. But it is what it is. When you are cruising, have you determined if you’re on the mains or the transfers? Depending on your answer the requirements to lean it on cruise are different.
An easier, less invasive [ 5 min job ] method to see if you are on the mains: fit IABs in place of the MABs. The IABs are considerably larger. According to the Turk theory, the mains should come in much earlier & be very rich....
Ironmike
Well-Known Member
all I can tell ya is cruising for me is anywhere between 2600 and 3200 RPM.
Why the hell did they can Newbomb?
He's just on a little vacation, should be back on the 22nd or so.
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