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Discussion Starter · #1 ·
Hi, I have a problem I can't seem to figure it out. At low RPM it builds boost fine then the boost falls off as RPM increases. I can get 19lbs in 1st & 2nd but by the end of the gear it is down to almost 16lbs. When it shifts into 3rd it goes to 20 to 21lbs and holds pretty good. The car runs good 12.30's @ 108.5mph. (Stock turbo, KB Big Boy, Ported iron heads, 3000 PAT's LK-up, Tho I have not locked during a run yet. KB Hi-LO Pro chip, Slicks, Ford Super coupe injecters, Wastegate housing fender dump.) I have tried bleeder valve. Grainger valve. I can't seem to get high boost to hold in the lower gears without getting way high (TO HIGH) in the upper gears. Am I running out of Turbo (Not enough CFM?) Any help would be appreciated.

Thanks, Mike
 

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to me that sounds like its in the chip.
 

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I have the HI/Low chip in one car and it does give it more boost in 1st and 2nd and then pulls back boost in 3rd and 4th. But it sounds like your getting boost creep in 3rd. Your going to need to open up your by-pass hole on the turbo.
 

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Hope you are running really good gas, or that chip will lead to misery on modern gas. Too much timing

Time for a modern chip. BTW, that's the reason it is called hi-lo.. :)
 

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Discussion Starter · #5 ·
Hi, Thanks for the replies.

I am leaning towards an exhaust leak but I can't see or hear any. I put a very thin coat of HI-Temp RTV on every flange and cross-over joint. I have the larger wastegate hole about 15/16" to 1". with good alighnment 1/16" to 1/8" puck contact all around. I did try running the car with the wastegate disconnected and at the very top of 2nd gear I would get 5 - 6lbs boost. Then I removed the turbo exhaust housing and ported and contoured the inlet around the wg hole (Inside only, did not touch the puck face side) I contoured the inlet of the turbo to the wg hole. I went for another run and it would only build about 3lbs at the top of 2nd. (with WG disconnected) Allthough this mod should help with boost creep not the problem i am having.

I am using an OTC 2000. This is with about 7 Gal. 100 octane (93 octane w/30% Xylene ?) to that I added 4 Gal. of C116. I should be in the range of 105 - 106 ? Early runs (hotter out) I got 3 - 5 deg. knock. Latter and a little cooler (about 78 deg.) I got 0 knock.


Thanks, Mike
 

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96 octane should be enuf these days :)
 

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Ckeck your IC hoses as well, if they are old they maybe flexing and/or leaking.
 

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stf420 said:
Hi, I have a problem I can't seem to figure it out. At low RPM it builds boost fine then the boost falls off as RPM increases. I can get 19lbs in 1st & 2nd but by the end of the gear it is down to almost 16lbs. When it shifts into 3rd it goes to 20 to 21lbs and holds pretty good. The car runs good 12.30's @ 108.5mph. (Stock turbo, KB Big Boy, Ported iron heads, 3000 PAT's LK-up, Tho I have not locked during a run yet. KB Hi-LO Pro chip, Slicks, Ford Super coupe injecters, Wastegate housing fender dump.) I have tried bleeder valve. Grainger valve. I can't seem to get high boost to hold in the lower gears without getting way high (TO HIGH) in the upper gears. Am I running out of Turbo (Not enough CFM?) Any help would be appreciated.

Thanks, Mike
My thoughts:

Since the chip references rpm's at many levels to control boost, it is possible that this is your problem. As I have no knowledge of what's in the chip you have though, I can not say for sure. You could have two problems. The second (as mentioned by forzfed) being boost creep. Maybe your solenoid is not moving far enough to get the job done. How are your vacuum hoses going to the solenoid? However, alternately your boost levels could be set higher for third and fourth in the chip, but that would be odd. As has been suggested by Mr. Wood, a new chip would be a good idea. Cheap fix, or even if no help with this problem, it will help other areas no doubt.

Hope you get it figured out soon.
 

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Discussion Starter · #9 ·
Update

Hi,

Update:

Installed ALKY. Same boost problem but went 12.20's @ 110mph. There was an engine noise so pulled motor to just check it over everything was fine (bearings and lifters). I installed a Completely stock heads including springs mileage unknown w/stock big neck stock intercooler. Now boost stays rock steady 22 to 22.5lbs. No creep, No drop, No spike. But I could only got a 12.40's @ 106.8mph. Seems like the heads were just flowing more air than the turbo could keep up with? I did try a TA60 with the ported head setup and the boost held fine. With first time out minimal tune time. The car went 11.70's best ET with 1 run netting 117mph.

T.I.A. Mike
 
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