Part Throttle Detonation

Flex

Registered User
Heya bro's,

Here's the scoup. I was trying to track down a problem with the car dying under boost on the weekend and I discovered that my factory blower wasn't doing too good. I had a new rectangular waiting so I figured what the heck.

I installed;

1.) A brand new rectangular port.
2.) A Magnum Powers Inlet.
3.) A BBK 75mm TB
4.) Replaced the 73mm C&L with a 76mm C&L with a purple sample tube.
5.) 42lb Injectors.
6.) The tube from my MP Cold Air Kit.
7.) An aluminum 10% in place of the steel one on my Oval.

The performance difference was substanial and the boost gauge pegs instantly. Problem is that I get a fair amount of part throttle detonation. I am talking about just a small amount of gas. Not a lot at full throttle or with a heavy foot.

Are the injectors too small? Is the 10% pulley too much for the car with no exhaust but if so why only a part throttle?

I have a double IC with fan to install and a portion of the exhaust system. I can always yank the 10% pulley and change to a 5% JS if the consensus is the car could handle it.

Thoughts my brotha's.
 
part throttle air flow is up leading to higher combustion chamber pressures, and at your existing octane, detonation occurs.

Try pulling a degree of timing at the rpm you are seeing the detonation, or try to pickup another octane point (i.e. if you have 91 octane, try a load of 92).

oh.. or you have a vac leak and are running too lean?
 
Mike,

She idles with about 16 inches of vaccum and it will hit 20 when I am coasting at speed.

The highest Octane available without help is 91. I have to add Xylene to bring it up or run race gas.

My ECM is not chipped yet so I can't play with the timing. I have a Shiftmaster version 5.1 board but didn't install it as I don't have the correct cable to attach it to my bro's laptop.
 
Pulley and injectors have nothing to do with part throttle operation. I don't see any mention of a tune. If you don't have a tune the whole combo is fubar.
 
Hey David,

I was hoping you would chime in. No tune brotha. What do you suggest? Should I get something from Fraser or should I try to run the shiftmaster setup if I can get the proper cable for the laptop?
 
I was thinking that the bigger C&L was a problem having read a few threads where a tune was needed to run one properly. I swapped it out after David's comment for the 73mm with a red tube and the engine is running much smoother. No part throttle lug and detonation as with the 76mm.:)

Looks like ole Fraser is gonna have to hook me up with a quarterhorse.
 
I was thinking that the bigger C&L was a problem having read a few threads where a tune was needed to run one properly. I swapped it out after David's comment for the 73mm with a red tube and the engine is running much smoother. No part throttle lug and detonation as with the 76mm.:)

Looks like ole Fraser is gonna have to hook me up with a quarterhorse.

Go ahead, add another grey hair to my balding head :p ;)

Fraser
 
Fraser loves to tune, if it wasnt for tuning he would have to do something real boring like work on his cars. :)
 
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