Test N Tune friday night

[trashmechlv]

Got my car hooking well this time out. Solid rear lower control arms and Hellwig bar on stiffest setting, new Hoosier DOT drag radials. Fresh valve springs last week. I have Scanmaster but no Powerlogger (I now see the need for this doing the fine tuning). Car has TT 5.7 race chip on 100 octane. Always showed rich on street so I pulled 2.3% fuel overall from default setting before I hit track.
first pass at 22lb boost, launch with maybe 1lb boost (first pass jitters) 60'=2.03 1/8mph 83.5  1/4= 13.15 @ 102.7  bit lean O2 739 and 1.2kr
2nd pass set fuel from 125 to127 overall, launch 4lb boost 60'=1.83 1/8mph 84.2 1/4= 12.80 @ 103.1 (forgot to get readings was jacked about hitting 12s and listening to guy in brand new CTS-V that I spanked 
3rd pass 24lb boost, 60'=1.87 1/8mph 84.6 1/4= 12.82 @ 103.8  real lean O2 687 and 3kr. (I have an air psi reg for boost control so hard to set)
4th pass 24lb boost, added fuel to 132 overall. 60'=1.86 1/8mph 84.2  1/4= 12.85 @ 103.4  O2 at 760 and 1.5kr
So car seems to run same on 22lb verses 24lb boost. My 60' could be better but I cant build more than 4-5lb boost on brakes before rpms hit 3k and tires turn. Should I pull 1st gear only fuel to build more boost on line? My MPH seems low, I just did comp 980 springs, car pulls to 5k rpm good now, used to fall on its face about 4600. Would the Vegas elevation 2200ft affect power that much? Temps were 85 and 20% humidity. Any advice from the gurus appreciated on dialing in. Powerlogger has to wait a while, funds low. I am happy with cars improvement so far.
 
 
 
 

[Steve Wood]

I think you were right on the ragged edge for the gas in the tank.  Took a lot of courage to jack it up to 24 from 22 imo.

The car only picked up 19 mph if I subtracted right in my head on the last 1/8 mile which is low.  I would expect at least 22 mph gain.

If you were seeing 3000 rpm on the converter, that is a lot for a TE44 and I would have expected to have seen 8-10 psi of boost and blowing your tires away.  Do you have a leaking downpipe, cracked header, or a puck that is not covering the hole completely in the wastegate?

LV altitude will hurt quite a bit compared to the guys down close to sea level.

I never had much luck with the air regulators and hard to dial in.

I would buy or make a manual controller or use the stock wastegate solenoid if it works.

You are just a pass or two away from blowing something at those O2s.  I would be scared to death of anything under 760

[Steve Wood]

You did not mention if your fuel pressure was tracking.  Be sure that it is or this could get even more expensive than head gaskets

Also make sure your rear brakes are adjusted up properly.

[trashmechlv]

Thanks Steve, appreciate your help. I have a fuel gauge rigged up to a hose, I will check fuel psi under boost. Car has ATR stainless headers I believe. I don't see or hear any exh leaks. Has 3" downpipe with ATR external wastegate that I plumped psi regulator into. The TT paperwork says o2 on 100 octane can run a bit leaner 750-800. I was trying to get it around 750-760. I will try to tighten rear brakes up some more, would like to see my 60' a little quicker. The Hoosiers at 22lb cold pressure dead hooked leaving around 4-5 psi. I see my next purchase needs to be Powerlogger.  We have 2 more TnTs in October before they stop for the year. Will do my homework and see if I can improve my times and run safer. 22lbs boost seems like my max on 100 octane.

[Steve Wood]

PL would make it a lot easier to figure out what is going on.  I suspect 22 is about it on 100 without pulling timing out.

I pull more boost than that on a 44 with about 2600 rpm so that makes me suspicious unless the car is very rich in first/second which is a possibility on a TT chip.


With the car fully warmed up and the O2 sensor hot, build boost against the brake and see what your O2s are reading.

yes, you can be a bit lower on O2s on higher octane gas, but mid 700s would be about it.

[motorhead]

Do you have a full list of modifications?

[trashmechlv]

Do you have a full list of modifications?

My sig info, stock unopened engine. 100k miles. Doesn't smoke or use oil (just leaks it). 28" tall tire. Would the speedo being off 8-10 mph from the rear tire cause an issue with the TT chip? I just ran car with a fuel psi gauge and pressure rising consistant with boost. I have boost at 21 and chip overall fuel at 127 now. Fuel psi at idle with vac line on is 38. made 2 pulls on street thru 1st into 2nd gear, O2 on scanmaster 789 and 770 no knock. I stalled car on the brake to 3000 after driving and my O2s were all over the place, jumping from 800 to 560 to 750 constantly random numbers. I never notice O2s doing that when Im making a WOT run.

[Steve Wood]

Why are you looking at fuel pressure with the hose on?  that will vary with the amount of vacuum the engine is making at the time.  Set your fuel pressure at 43 with the hose off...that way vacuum is not affecting the fp at zero vacuum/zero boost.  then If you are running 22 of boost, you should see 65 psi of the fuel pressure gauge with the hose back on.   Be sure you verify that the fp is correct at the top end of third gear...not at low speed or the top of first or second.

When you are at 3000 rpm against the brake, the computer is in closed loop and trying to adjust the fuel based on the input.  When you go wide open throttle, it goes to a fixed fuel curve and will be pretty steady.

See my notes on how I would tune similar to yours here   http://www.vortexbuicks-etc.com/TuningBasics.htm#Engine_Tuning

[motorhead]

Do you have a full list of modifications?

My sig info, stock unopened engine. 100k miles. Doesn't smoke or use oil (just leaks it). 28" tall tire. Would the speedo being off 8-10 mph from the rear tire cause an issue with the TT chip? I just ran car with a fuel psi gauge and pressure rising consistant with boost. I have boost at 21 and chip overall fuel at 127 now. Fuel psi at idle with vac line on is 38. made 2 pulls on street thru 1st into 2nd gear, O2 on scanmaster 789 and 770 no knock. I stalled car on the brake to 3000 after driving and my O2s were all over the place, jumping from 800 to 560 to 750 constantly random numbers. I never notice O2s doing that when Im making a WOT run.

There can be some effect from the tires being taller, but nothing too significant - but may be slowing you down a bit.

Your O2s will switch during normal driving conditions (closed loop), and will lock out during WOT blasts.  Adding a bit more 3rd/4th gear fuel will add a safety margin, as will dropping a degree or two of timing.

All and all I'd say you are close to optimized for the parts you have, on the fuel you are running, and at the elevation/weather conditions you are racing at.  Personally I hate people who argue weather and Density Altitude (DA) in order to make excuses for their "slow" car - but, it is a variable that must be given consideration when evaluating power production.

[Scoobum]

Your MPH going through the traps is about 7-10 lower than what I would expect...somet hing's up. Do you know what your RPM's were at the traps? I'd like to crunch the convertor slip. Leave the low gear fuel/timing on the default setting until you get PL...otherwise you're guessing...whi ch ain't good.

[trashmechlv]

I don't know what rpms were. Wish I had checked because that had popped into my head today. My shift light is set at 4900 so I can see it flash quickly before my trans shifts as I leave it in drive. I know the light doesn't flash thru the traps so its def under 4900.
As Steve mentioned I need to run my fuel psi gauge tied on my wiper next time I go to track to check psi at the top end of track. I don't have a full time gauge mounted outside. The converter is new from PTC and is a non lockup. Thanks for all the input from everyone.

[motorhead]

I don't know what rpms were. Wish I had checked because that had popped into my head today. My shift light is set at 4900 so I can see it flash quickly before my trans shifts as I leave it in drive. I know the light doesn't flash thru the traps so its def under 4900.

Yup, that would be your tires contributing.

[Forzfed]

With my low milage car, which is all stock I left it in OD with 28" tall tires and went through the traps at 4400rpm.  Car went 12.3@108mph.  With 100k on the motor there could be a few little things you need to tweak.

[trashmechlv]

OK I was not correctly figuring my fuel pressure out yesterday as it rises with boost. As Steve said I should be starting at my base pressure with line off which is 43. I misunderstood and was just going from the 38 I saw on the gauge with car at idle. So my car is running 21lb boost now and my fuel pressure at boost is 62. So I am 2psi short at full boost. Is that enough to cause low power issue on the big end and only pick up 19mph instead of 21-22mph? Thanks for the help.

[Steve Wood]

may well be a gauge accuracy problem...I would keep my eye on it and if drops from that, then I would thinking about fixing it...but at this point, I would not be convinced it was bad