Turbo lt1 questions
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On The Tree
Joined: Apr 2010
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From: Philly
Turbo lt1 questions I turboed my 95 Impala a couple months ago and now Im working on the tune.
My first question is, am I maxxing out my turbo? Im making a full 10lbs of boost at 3600 rpm. I get about 5-6 deg of spark retard at 3600 rpm so I wont rev over that. The turbo is a HPPerfemance built 60mm garret with a p-trim wheel. Not sure of the wheel sizes. It has a .70 a/r compressor side and a .96 a/r turbine side with a 3inch downpipe.
The engine compression is 9.7:1. I have a 10lb spring in the tial 44mm wastegate.
Do I need to go with a bigger turbo?
My second question is, what are some of the reasons why I have so much spark retard?
Im running autolite 103's gapped at .038".
At one point I took out so much timing that the car just didnt wanna go anymore. I must be missing something but Im not exactly sure what.
My afr's are at 11.5-11.7 when Im in boost so I believe that Im getting enuff fuel but I still have alot of spark retard.
Im tuning using the MAF sensor rite now. I havent quite nailed sd tuning yet. I have tried it a couple times but I decided to go back to MAF for now.
My first question is, am I maxxing out my turbo? Im making a full 10lbs of boost at 3600 rpm. I get about 5-6 deg of spark retard at 3600 rpm so I wont rev over that. The turbo is a HPPerfemance built 60mm garret with a p-trim wheel. Not sure of the wheel sizes. It has a .70 a/r compressor side and a .96 a/r turbine side with a 3inch downpipe.
The engine compression is 9.7:1. I have a 10lb spring in the tial 44mm wastegate.
Do I need to go with a bigger turbo?
My second question is, what are some of the reasons why I have so much spark retard?
Im running autolite 103's gapped at .038".
At one point I took out so much timing that the car just didnt wanna go anymore. I must be missing something but Im not exactly sure what.
My afr's are at 11.5-11.7 when Im in boost so I believe that Im getting enuff fuel but I still have alot of spark retard.
Im tuning using the MAF sensor rite now. I havent quite nailed sd tuning yet. I have tried it a couple times but I decided to go back to MAF for now.
Have you tried a little no-lead race gas to eliminate the possibility of real knock?
What mods are done to the engine, things like forged pistons and roller rockers can trigger false knock readings.
What mods are done to the engine, things like forged pistons and roller rockers can trigger false knock readings.
TECH Fanatic
Joined: Feb 2006
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From: CT/NJ
Also do a WOT chop and read the plugs to make sure you aren't running lean in a couple holes.
Thread Starter
On The Tree
Joined: Apr 2010
Posts: 162
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From: Philly
The pistons are coated skirt speed pro (forged) and I also have summit 1.5 roller rockers. Those things do make some noise. I checked them a bunch of times just to make sure they werent loose. I found that they are just noisey.
Thread Starter
On The Tree
Joined: Apr 2010
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From: Philly
Maybe I should get a knock module.
have you tried pulling timing at the rpm your are getting knock? 1-2 degs of retard might be all you need. I've found that all engines have a rpm that they tend to knock at when pushed. Just pull the timing in that area and see if when you go beyond that rpm you don't get any KR.
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Thread Starter
On The Tree
Joined: Apr 2010
Posts: 162
Likes: 0
From: Philly
have you tried pulling timing at the rpm your are getting knock? 1-2 degs of retard might be all you need. I've found that all engines have a rpm that they tend to knock at when pushed. Just pull the timing in that area and see if when you go beyond that rpm you don't get any KR.
The race gas test is next.
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