More boost = slower times...help troubleshoot inside

[bluehair]

hey guys..took car to track this weekend and it ran slower each pass...scratching my head. please help. mods are below...

206 cam, mild port on heads, intake, RJC plate, new valve springs, etc..., ATR SS headers, 3" exhaust, stock lock up converter, TT chip set for 93 octane, 19/17 on the timing and at 16lbs boost. stock rear, turbo, intercooler. 60# injectors, hot wire kit to fuelpump....so pretty mild to stock car. i have ran a best of 8.34 on 93 octane and not touching the chip adjustments. 1.80 60ft. that was a few weeks ago. now to this weekend......

55 deg weather in KY, so good cool air for power.
27x10.5 hoosier quick time pro's, stock T-type wheels.
put race gas in, left boost at 16 lbs, bumped timing up to 23/21 since i had good fuel and it ran first pass there after driving for an hour 8.29 @ 82.6 mph. with a 1.83 60ft. so not to bad...i didnt think. taking off about 5lbs boost. zero knock.

So i got frisky and turned boost up to 18lbs. left everything else alone. ran it twice that way and best was a 8.38 @ 82.4 mph, with a1.93 60ft. i was leaving at 8-9lbs of boost, didnt feel like it was spinning, but who knows...still slowed down 60ft. and mph and et. so i was like what the????

still no knock i was like what the hey..so i turned it up to 19 1/2 lbs boost, timing left alone at 23/21 and ran it, same deal, 1.90ish 60ft. and same mph as before...zero knock. car felt good just times sucked and seemed to get slower. so i took some fuel out of 1st and 2cnd gear -3% i think, to try and help 60ft. times...and it ran worse. zero knock but ran like a 8.40ish...at 81mphish... i gave up and drove home. now frustrated....

i did pull a couple of plugs today just curious, and they are autolite's R43TS's gapped at .040 didnt look all that great but didnt look terrible either.

is my plugs gapped wrong or wrong heat range for that fuel and boost?
is my converter going bad? trans? where and why do i seem to be losing power? if it was spinning wouldn't my mph still go up with more boost? but taking off at 8-9lbs of boost i think it hooking o.k. just not feeling its best.

help......???? ideas?

 

[8AV8]

Is it the stock trans?

 

[T-top87GN]

After 18, if I recall correctly, the stock turbo is only pushing hot air. That's not going to help you go faster and will actually slow you down.

 

[bluehair]

sorry i meant ACdelco plugs not autolite.

ive had other turbo cars with stock turbo's and gone as much as 22 lbs and made big gains so i know that the 18lb threshold is debatable but all cars are different...but point here is it slowed down from 16lbs to 18lbs...no matter if i went any further.

stock trans but has been gone thru and converter fresh'nd from previous owner...it seems to shift good....but who knows.

 

[Boost231]

i know this probley isnt your problem but i would change the plugs out to some ngk ur5's gapped at .032 if you want ac delco get the AC CR42TS plugs gapped at .032

 

[bluehair]

i thought the gap was a little high myself but how much would that effect my power? boost? etc....just curious.

 

[imjoesnuffy]

I'm certainly no expert, but I'd try.....

Gapping the plugs at .35. Put some fresh plugs in before you go back. If they had been in a while and had fouled. It could be blowing out the spark.

Sounds like you may be running rich, do you have a way to monitor your A/F ratio or at least O2 millivolts?

The base settings for race gas that I had in other chips was 26/24, might help bumping it up if you are running 110 or better octane. Anything over 25psi of boost I use C16 or Q16.

Also what air pressure you running in the slicks, I haven't used that particular brand or size, but had good luck with 12-14 psi in MT Drags. Your car looks lowered, might want to check your pinion angle as well.

Something else that has worked for me was getting the boost were I wanted it and then making changes to the fuel and timing. Boost, then timing, then fuel. Obviously fuel dependant on the first two. Then trim out or add fuel as needed as conditions change.

Hope you get it sorted out.

 

[moose]

For what it's worth i'm curious, how long did you let the car cool down after driving it for an hour to the track? I have found that my car normally run's better the first pass after driving it to the track, i normally stand around for a while and let it cool way down after the drive. The other run's are closer together without long cool down's and it effect's my ET's about the same as your's are showing. Just a thought.

 

[bluehair]

i let it cool down a bit, changed tires, walked around..about 30-45 minutes...the other runs of the night had more cool down in between them, so "generally" they should have been quicker because of more cool down but they werent.

 

[bluehair]

I'm certainly no expert, but I'd try.....

Gapping the plugs at .35. Put some fresh plugs in before you go back. If they had been in a while and had fouled. It could be blowing out the spark.

Sounds like you may be running rich, do you have a way to monitor your A/F ratio or at least O2 millivolts?

The base settings for race gas that I had in other chips was 26/24, might help bumping it up if you are running 110 or better octane. Anything over 25psi of boost I use C16 or Q16.

Also what air pressure you running in the slicks, I haven't used that particular brand or size, but had good luck with 12-14 psi in MT Drags. Your car looks lowered, might want to check your pinion angle as well.

Something else that has worked for me was getting the boost were I wanted it and then making changes to the fuel and timing. Boost, then timing, then fuel. Obviously fuel dependant on the first two. Then trim out or add fuel as needed as conditions change.

Hope you get it sorted out.

i have a scanmaster and the mv have been reading 800 or so at idle and 750ish in third gear.

the tires are like ET streets, there a street sticky but i was running 16-17 psi that night. was doing a healthy burout with linelock also.
what should be my pinion angle, and yes it has been lowered.

im going to buy new plugs tomorrow...i know its been debated million times on here but what would be my best bet with race gas and 20lbs boost? gap and plug type?

i have probably 2-3 gallons of 93 octane left in the tank, with 5 gallons of air plane fuel, then 5 gallons of 110 on top of that...so its a volitile mix!

but no knocks as of yet...so i think i want to stop at 20lbs. boost...and do timing and fuel at that point. just wasn't sure on plugs, trans, and my slowing down problem...wierd....these cars can be so frustrating at times. worse than my wife.

 

[moose]

I would think if you went up on boost and the car slows down then it would be a fuel issue, i know your showing no knock but my car has done the same exact thing before when i went up on boost. My times slowed down one night when raising the boost and no knock but when i turned it back down the car picked back up. I'm not sure but i wonder if there's a fine line between knock and no knock where the car loses power at a little higher boost without knock.

 

[moose]

Would have been interesting to turn the boost back down and see if it picked back up again? Since it ran a better time on lower boost.

 

[Boost231]

NGK UR5's gaped at a tight .032

 

[imjoesnuffy]

i have a scanmaster and the mv have been reading 800 or so at idle and 750ish in third gear.

the tires are like ET streets, there a street sticky but i was running 16-17 psi that night. was doing a healthy burout with linelock also.
what should be my pinion angle, and yes it has been lowered.

im going to buy new plugs tomorrow...i know its been debated million times on here but what would be my best bet with race gas and 20lbs boost? gap and plug type?

i have probably 2-3 gallons of 93 octane left in the tank, with 5 gallons of air plane fuel, then 5 gallons of 110 on top of that...so its a volitile mix!

but no knocks as of yet...so i think i want to stop at 20lbs. boost...and do timing and fuel at that point. just wasn't sure on plugs, trans, and my slowing down problem...wierd....these cars can be so frustrating at times. worse than my wife.

Id venture to say you have around 102 octane in the tank. 20 lbs should be easily doable. Id set the timing around 24/22 to be on the safe side, starting out. How much leaded AV/race gas have you ran past that O2 sensor? I used to go through them really quick when running race fuel. The reason I would guess it is running rich is because of the colder air, more dense. I myself run Autolite 23's if my memory serves me correctly, they are cheap and were recommended by a friend in Indiana who knows a lot more about these cars than I do. I gap them between .32 and .35. .35 should be fine with only 20 psi.

If they are like MT ET street radials, I believe it is recommended to start at 24 psi and work your way down if the track isnt hooking. Might do a little reseach on what works best for that particual tire.

Pinion angle should be -2 for a regular car, not sure what effects lowering it can have, and where it should be once lowered. More research awaits.

I'll be back from Afghanistan in Nov, hope to see you and Ricky at the Valley if it is still open. If not there is always next year.

Take care,
John

 

[8AV8]

I bet the clutches are starting to go. If it is a stock rebuild and a warmed over D5 I bet you are starting to flare an the 1-2 shift....the D5 will get very hot if you are leaning on it for too long at the line. Are you logging any of this?

Once you start making power the stock tranny starts wanting to squeal uncle.

my .02

 

[WSLN 6]

What rpm do you go through the traps at? Are you locking the converter at the line?

 

[bluehair]

not locking the converter no, i hear that that is hard on the converter and the life expectancy so i choose not to...i have no idea what my rpm's are across the line. all i have is a scanmaster at this time so no logging of anything..good ol numbers and pencil and note pad

 

[scot w.]

Thought I might add more info on this cars Mods so people can give better advice based on the mods! Chad the last owner had listed this at one time.

Bluehair- You might want to add this stuff to your sig for future refference.

It's an 87 Limited. 128k miles. Motor is a near stock rebuild with:
Motor has 15k miles,
tranny has 12k miles
206/206 cam.
turbo tweak chip.
60# injectors.
ATR stainless headers,
2.5 stainless downpipe and factory style stainless exhaust with.
Heated O2 sensor,
hot wired Walbro 304,
cold air kit.

Tranny has been rebuilt and it has a PTC 12" 2200 stall l/u converter. G80 posi. TCC solenoid has just been replaced.

 

[WSLN 6]

It's going to be pretty tough to find out what's going on without a scantool/rpm gauge etc. I would be going shopping before flogging it any further.

 

[challengermike]

I have been going threw the same thing,i havnt checked mine yet but i am also thinking its a fuel issue,except mine i cant get any more than 630 mv in third wide open.I even uped the chip to 18% in fuel and 10 pump speed on the alky and it didnt help.