Questions
05-02-2002, 02:08 AM
#1
Staging Lane
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Questions I know this is the LS1 board and I own a LS1 but a friend of mine needs some help.
He has a 97 Cobra. He blew the stock motor up b/c of nos and has now put a new forged everything motor in it. He has also has a stage 3 port and polish on heads and intake with the runners cut out or welded shut in the intake. He also has added BBK LT's and he put the nos back on.
He has stock fuel system, stock MAF, stock TB, NGK TR55's gapped at .035, and basically stock filter. He's running 32psi of gas and unplugged running 40 psi. Here's why I'm posting this, the car has some sort of miss until it reaches around 3800 rpm. When it reaches around 3800 it's like turning a water faucet on. It runs great. Runs like it should run. From 1500 to 3800 it lags bad. It will jerk, backfire, pop, normal signs of a miss. He changed the spark plugs already.
He dynoed the car before it blew and it dynoed 268 hp and 272 tq, that was with a k&n filter and x-pipe. After new motor and porting he has dynoed a best of 279 hp and 284 tq. Also the car is using oil. Since his last oil change which has been almost 3000 miles he has added almost 4 quarts, and he doesn't has any oil leaks. But it doesn't smoke in normal driving. When you get on it the car blows out black smoke. You can also smell gas, like it's running rich.
Questions are:
What would be causing the miss?
Why so low on the dyno?
What would be causing it to use oil?
Would computer tuning help, if so where?
Thanks in advance for reply's and if anymore info. is needed I will get it. Thanks again
He has a 97 Cobra. He blew the stock motor up b/c of nos and has now put a new forged everything motor in it. He has also has a stage 3 port and polish on heads and intake with the runners cut out or welded shut in the intake. He also has added BBK LT's and he put the nos back on.
He has stock fuel system, stock MAF, stock TB, NGK TR55's gapped at .035, and basically stock filter. He's running 32psi of gas and unplugged running 40 psi. Here's why I'm posting this, the car has some sort of miss until it reaches around 3800 rpm. When it reaches around 3800 it's like turning a water faucet on. It runs great. Runs like it should run. From 1500 to 3800 it lags bad. It will jerk, backfire, pop, normal signs of a miss. He changed the spark plugs already.
He dynoed the car before it blew and it dynoed 268 hp and 272 tq, that was with a k&n filter and x-pipe. After new motor and porting he has dynoed a best of 279 hp and 284 tq. Also the car is using oil. Since his last oil change which has been almost 3000 miles he has added almost 4 quarts, and he doesn't has any oil leaks. But it doesn't smoke in normal driving. When you get on it the car blows out black smoke. You can also smell gas, like it's running rich.
Questions are:
What would be causing the miss?
Why so low on the dyno?
What would be causing it to use oil?
Would computer tuning help, if so where?
Thanks in advance for reply's and if anymore info. is needed I will get it. Thanks again
05-02-2002, 05:05 AM
#2
On The Tree
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Re: Questions I think half the reason for the blown motor using NOS is the stock fuel system. I dont know anyone in their right mind that does this. Everytime you add horsepower you have to make sure you have enough fuel and that the fuel system can keep up with the RPMs. This might have a little something to do with he current N/A problems.
I HIGHLY recommend he gets new fuel injectors and pump (AND FILTER!) as well as a new igition. I dont pretend to be a NOS expert, I fact I wont use it. However make sure that, if he gets it, the new ignition has the proper timing/retard.
The most common reason for "burning oil" is oil leaking into the combustion chamer through bad valve seals. One would think that this wouldnt happen with his new heads and all around new gaskets, but you never know. I hope this new engine work was done through a professional mechanic.
I might also look into cam timing. The explaination for the smoke maybe be improper opening and closing of the vavles. Unlikely, but anything is possible. I would really have this new or rebuilt motor checked out. Seems to me he got the shaft.
on the joking side, he is one one that bought a 4.6 <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> go figure.
I HIGHLY recommend he gets new fuel injectors and pump (AND FILTER!) as well as a new igition. I dont pretend to be a NOS expert, I fact I wont use it. However make sure that, if he gets it, the new ignition has the proper timing/retard.
The most common reason for "burning oil" is oil leaking into the combustion chamer through bad valve seals. One would think that this wouldnt happen with his new heads and all around new gaskets, but you never know. I hope this new engine work was done through a professional mechanic.
I might also look into cam timing. The explaination for the smoke maybe be improper opening and closing of the vavles. Unlikely, but anything is possible. I would really have this new or rebuilt motor checked out. Seems to me he got the shaft.
on the joking side, he is one one that bought a 4.6 <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> go figure.
05-02-2002, 08:40 AM
#3
12 Second Club
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Re: Questions Hey Brian, post this question over at www.corral.net in the modular section, and those guys could answer your questions alot easier and faster than over here. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
05-02-2002, 11:52 AM
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Staging Lane
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Re: Questions In fact patty I did and out of 200 people lookin at it, I got one reply. So no they dont intend to help over there, or they dont know anything. Oh this is Chad posting cause I dont have a name on here.
05-03-2002, 03:59 AM
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Staging Lane
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Re: Questions Appreciate the reply Andy West..could it be something to do with timing? All of us are clueless as to what could be up with his car with the lag between 1500 to 3800..ttt.thanks for any help!!!