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Discussion Starter · #1 ·
well basically i have a 80mm single turbo cobra pushing 16 psi of boost. i am running an sct ba 5000 in my intake pipe, big return fuel system, ams 1000 co2, sullivan intake, stock motor and so on.

basically when i get in the 5000 rpm range, the car seems to have an rpm hesitation as it is going up. some what of a shudder/ breaking up also. i cant figure it out for the life of me. it does it on the dyno as more on the street. i am running a 50/50 mix of 93 and 110 leaded fuel. i changed the plugs and the car is running a lil rich in the upper rpm range all the way to redline.

anyone have any thoughts on what this could be?
 

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Discussion Starter · #3 ·
ngk tr6 at 0.28 gap, see i wa thinking that maybe i need to move to a colder plug also. for the record i just put a new set of plugs in it and am going to give it a run tomorrow or something and see if it still happens. i hope it was just the plugs.

ill also be putting in some fresh fuel and see if that was the issue.
 

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16 psi of boost though? I wouldn't think that would necessitate a crazy cold plug. You could always try one step colder though.
 

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Really? When do the tr6's usually give up? Are they a bad idea i take it on over 20lbs?
 

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In reality the TR6 is a hotter plug and should be easier to fire. You do need a colder plug... but it's gonna be harder to fire. I used Br7ef's but noticed that they foul real easy, so i started using AR93's. The AR93's are colder than the br7ef's but won't foul as easy. Also i've never ran my gaps above .020. I set mine to .016-.018 and never had spark blowout til about 950rwhp through an auto. Go and ask any of the the big name turbo guys what they run as far as spark plug gaps and you'll see.
 

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I run Autolite AR93's gapped at .018, made 1160 wheel on 24lbs with zero blowout. I had nothing but trouble with the NGK's, all my issues went away with the autolites. If your stuck on NGK set your gap tighter and change your plugs often.
Agreed. NGK plugs suck with these turbo modulars. Everyone swears by them but I had absolutely no luck with them. AR93's are fantastic.

How rich are you running your setup? If it is really rich, it will break up on the top end as well.
 

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Discussion Starter · #13 ·
thanks guys for the responses, i am going to buy some ar93 and give them a shot. ill let you guys know how it goes later in the week when i get my car on the dyno again and het the tune re-checked.

as far as the tune goes i think i had it running between 10.8 being the richest and to 11.2. i will have to look at the graph again and get back to you, but i believe it was somewhere around there.
 

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thanks guys for the responses, i am going to buy some ar93 and give them a shot. ill let you guys know how it goes later in the week when i get my car on the dyno again and het the tune re-checked.

as far as the tune goes i think i had it running between 10.8 being the richest and to 11.2. i will have to look at the graph again and get back to you, but i believe it was somewhere around there.




Did you ever fix this issue
 

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Please do not open up 14-year-old threads and solicit a response to a 14-year-old issue. The OP has most likely sold the car and is no longer an active forum member. You will get no response, and you will clutter up the site with nonsensical decades-old issues that are no longer relevant to anyone. Please be more thoughtful in your participation.
 
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