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Resident Embraer Driver
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Discussion Starter #1
Random Question 1.
After playing around with my car on the street with the race gas and the race chip, what causes boost spike. I thought after I had my exaust leaks fixed this wouldnt happen, goes from about 23 to 25#'s when first spooling up then stays stable. could it just be a decrease after the 1-2 shift?

Random question 2.
Does everybody get Knock Retard when down shifting at highway speeds to pass?, 75mph approx?

Random question 3. Should I need 50# of fuel pressure to achieve 800 O2's on a pass with 23# of boost with 009's?

Joe

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1986 Grand National
TA-49, 009's, Hooker cat back, and all the other usual stuff

 

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My uncle is right...increased load may cause transitional knock, or it may be false caused by the detonation sensor being activated by the jerk of a hardshifting tranny under power.

With regard to 50# being required..that seems high to me. It could be the chip, it could be the pump, it could be the regulator, or a restriction in the return line or supply line.

The spike could be from a too small wastegate hole or a too tight actuator spring.





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My car spikes a little when it first spools up but I think it's just the shotty factory wastegate with an el cheapo bleeder. I'm guessing that it builds boost so quick that it can't release enough exhaust pressure quick enough to level off the boost right at 20psi. Perhaps a larger hole in the exhaust housing and a larger 'puck'would help.

The slightly leaner race chip and increased timing might make this spike more noticeable than your street chip. Justa guess. We'll see what Steve-O has to say, Zapper's right, experience pays...
or is it crime pays? I fergit.
 

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<....2seconds later>
damnit he beat my post.... I hate it when that happens


<....5seconds later>
Arggh! now I gotta wait for flood control!
 

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Resident Embraer Driver
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Discussion Starter #8
So I am thinking that boost spike problems could be wastegate related, the rod is tight but not excessivly, I can do it buy hand when its cold...
Solution, ask daddy for a Terry Houston For Christmas, I'll see if I can buy me a new chip


Boost spike at Highway speeds...
Solution, just dont downshift at highway speeds.

Fuel Pressure deal...
get rid of the junk BGC stock looking regulator

ok thanks for the help
Joe

[This message has been edited by Grannynational (edited December 03, 2001).]

[This message has been edited by Grannynational (edited December 03, 2001).]
 

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Joe, the THDP may help on the boost spike, but you'll have to enlarge the hole in the exhaust housing to take advantage of the THDP's larger puck. I have a stock elbow with a 1.25" puck and wastegate hole was .98" I was having boost spikes of 4-5 lbs when running over 20lbs of boost. I took the turbo off and marked the wastegate hole by putting antiseize on the puck surface. Used a dremel and opened the hole up. I radiused the "shelf" in the elbow near the puck. I still have the spike, but it is down to ~ 1 - 2lbs now. I believe that the stock elbow is allowing the exhaust to stack up, and a THDP would help me at this point.

Mike
 

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Why do you want 800mv? If you have octane, mid 700's will be fine. too much fuel pressure = a slow TR.

But then what do I know, I got one of those stock appearing BGC FPR's, too.


[email protected] of 46 psi of fp and bluetops. It looks stock, because it IS stock.


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UNGN
My Timeslips Page
My G-body Homepage
 

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Discussion Starter #11
I think I'll have to do that if I can get a THDP.
The next time out to the track I'm going to run less boost and a little leaner and see if it goes any faster. I was running rich for saftey sake cause, I only have a scanmaster for tuning so far.

UNGN, can you share some details about your 11 second runs with blue tops? What turbo, O2's?
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1986 Grand National
TA-49, 009's, Hooker cat back, and all the other usual stuff



[This message has been edited by Grannynational (edited December 04, 2001).]
 

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Originally posted by Grannynational:
UNGN, can you share some details about your 11 second runs with blue tops? What turbo, O2's?
From Mr. URL's recipe page:

Model/Year: 86 T-type
Short block: Stock 90K miles
Heads: Stock 90K miles
Intake: Stock lower, home ported stock upper with flow plate, 62mm TB
Turbo/Intercooler/Induction: TA49 home ported stock inlet bell/Stock
intercooler w/2.5" neck
Engine management: Stock, Thrasher 108 Chip
Fuel system: BGC fuel pump (W307), Walmart Hot wire, blue top injectors, BGC
stock appearing adjustable FPR @ 46-47 psi
Ignition system: Stock
Exhaust system: THDP, 2.5" non mandrel bent duals, Ultraflow mufflers
Cooling system: Stock
Transmission/torque converter: Stock with a shift improver kit, converter lock up switch
Suspension: Bilstein shocks, Sway Bars:ATR rear, stock front, removed for run, Pinion
snubber, right rear airbag @ 20-28 psi
Rear end: Stock
Wheels/tires: R: Stock w/275R60 BFGDR's @ 20 psi, F: Weld 26" M/T front runners (went [email protected] with the stock front wheels 205/60 bfgs).
Body/Interior: Body: stock with "export" front bumper brackets
Interior: Stock with dealer installed Flofit seats.
Fuel used/PSI boost: 114 octane, 23psi

Car weight 3600 - 3580lbs

Notes:
Best Track Time/60ft:

Best 1/4 mile: [email protected] (best mph 118.31)

Best 1/8 mile: [email protected] with a not so great 1.68 60ft

Weather in the mid 60's with good air.

Knock was in the <1 range, O2's were in the mid 600's (I trust O2 sensors as far as I can throw them)

Other parts of my combo not listed are a stock aircleaner canister/elbow with a 3" LT1 sensor and K&N cone filter inside.



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UNGN
My Timeslips Page
My G-body Homepage
 

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Discussion Starter #13
arn't mid 600 on the 02's extremely lean?

Joe

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1986 Grand National
TA-49, 009's, Hooker cat back, and all the other usual stuff

 

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Originally posted by Grannynational:
arn't mid 600 on the 02's extremely lean?

Joe
I guess. Like I said, I trust O2 sensors as far as I can throw them. In reality I would imagine its in the 750-760 range. My plate I put in my upper plenum must be giving me good air distribution - you're only as strong as your weakest cylinder.

I've run the same combo for over a year, changing very little. It ran 11.66 last year and 11.53 this year, no breakage (I had to buy a new starter, the original died), no damage. I guess I have close to 40 eleven second passes on it (with 300+ 12 second passes before that). I try to conserve my equipment by not leaving at 15 psi, running more octane than I may need and using drag radials instead of slicks.

I'm sure stuff will start breaking when I bolt on my heads I ported and get some bigger injectors, maybe a bigger turbo and a high stall converter. I've had it pretty good up to now.

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UNGN
My Timeslips Page
My G-body Homepage
 
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