LT4 GM performance parts LT1 to LT4 conversion kit

[dhiltgen]

I was thinking about buying a higher milage '96 LT4 as a lower entry cost project vette, but noticed a product listed in Summit Racing recently. Seems GM Performance parts is selling an LT1 to LT4 upgrade kit (heads, valves, springs, intake, HOT cam, 1.6:1 roller rockers, and gaskets) They claim the kit will turn out 425+ HP

Does anyone have any experience with this kit? Will it really turn out 425+ HP? Think it's CA smog legal?

If so, maybe a 94-95 with an even higher milage engine would be a nice base platform. Just have a machine shop do a bottom-end job and slap this on top. Plus the '95 and older computers aren't OBDII so life should be a little simpler...

 

[vader86]

Dont buy a conversion kit.

Buy the LT4 Hotcam kit w/RR, have the stock heads ported and the intake matched. Youll be faster than an LT4, and it'll be cheaper.

Add some headers, and youll put out more than 425Hp easily.

The LT4 hotcam must be 'detuned' to pass emissions, and the headers wont pass visual.

 

[Tuna]

I'm having the LT1-LT4 conversion done next month. After that, I'll let you know.

 

[sothpaw]

Vader,

Why would the headers not pass visual?

I thought the only federal rule was you must have cats, the same number and configuration as stock.

 

[vader86]

The Tech that looks over your car in CA will know that those headers arent OE. The Law says youre not supposed to tamper with ANY OEM emissions equipment except for replacement. The stock manifolds are covered in that, catback is not. CA is one of the few states that is a stickler for visual and sniffer.

It wont pass visual if the Tech has any experience.

Besides, the stock cats wont fit with LT headers and catback without welding on an LT1. You'd need bullit cats.

 

[Edmond]

Vader,

You are on the money! CA is much stiffer than any other state. That's what happens when you have so many cars there!

I still run all 3 cats but they don't bother with a visual here. I was told that the car should be able to run without the pup cats if it is tuned right. I believe the newer Z06's only have the main cat right?

Do you think shorty headers would do him any good or be a waste of money?

 

[vader86]

Since shortys are the only option, i dont think he has much choice. Theyll at least shave off 10lbs off the front end. The stockers are quite heavy. They should still give something like ~5hp at the least. I do believe there are several shortys with CARB numbers, but dont recall a brand at the moment.

Ed, your car will run just fine without the precats. Doesnt need tuning at all, it will still pass sniffer without them unless Illinois is as stringent as CA. So long as the main cat is good.

I dont know the LS engine's exhaust setup.

 

[wx briefer]

The performance upgrade to the LT1 by using HOT cam kit is a good step if you consider the rest of the valve train. However, remember that the higher revving LT4 heads have hollow stemmed valves for lighter, higher revving weight. The LT1 does not. And, unless you are wanting to turn higher revs, the LT4 kit is not worth it, in my opinion. So look at your options on lighter valves and/or higher pressure springs.

 

[atlride]

Lt1 2 Lt4

I was thinking about buying a higher milage '96 LT4 as a lower entry cost project vette, but noticed a product listed in Summit Racing recently. Seems GM Performance parts is selling an LT1 to LT4 upgrade kit (heads, valves, springs, intake, HOT cam, 1.6:1 roller rockers, and gaskets) They claim the kit will turn out 425+ HP

Does anyone have any experience with this kit? Will it really turn out 425+ HP? Think it's CA smog legal?

If so, maybe a 94-95 with an even higher milage engine would be a nice base platform. Just have a machine shop do a bottom-end job and slap this on top. Plus the '95 and older computers aren't OBDII so life should be a little simpler...

I did a Lt1 to Lt4 kit but it is a lot more to it then you think I have a 1994 it was fun but the money dose not stop at the kit but i will tell you that in the 1/8 i ran mid 8s and that was on stock tires that i could not get to hook i have a video of the run and the time more work to the kit than you think for just a bolt on but
Some things I added
Ram air
58mm Throttle body
Hooker headers
ecm programed
coolent bypass
opti spark
fuel ing 30lb
adj fuel reg
port polish the heads and port match
160 t
If you need more info let me know
Mark
blackcorvette6@aol.com