TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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It's finally time to rebuild the LB9 305 in my '91 Z28 5-speed. I'd like to upgrade the camshaft, but I want to stick with the 19lb injectors(I installed new Bosch injectors last year), the stock computer, etc....
I've already done all the "free" TPI mods, it has flowmaster exhaust, it will have headers/y pipe w/no converters, and the stock 3.42 rear. I'm not looking to go overboard, I'd just like to put in the new cam and leave the rest of the long block/electronics stock. Any ideas on cam size would be great, or if anyone knows of a proven combo...that would be great also.
I just recently upgraded my L69 with TPI, installing an LT1 cam. After a lot of research, this came out as about the most lift the stock engine could handle without any Head Mods. Runs very strong, idles great. Your new injectors will be fine, but you might need a slight tune on the ECM to take advantage of the cam. Might get by without it, but I have MAF and it is a little more forgiving on changes. While you are changing the cam, be sure to change the timing chain as well- good insurance. Might also want to install new springs and valve seals.
I have an LT4 cam in my LB9 and it runs hard with it. With this cam however you will need a tune. Its not even the hot cam but its got a nice idle for a 305 and a ton more balls than any N/A 305 should have lol.
I basically have the same car. Went with comp cams xr258hr12. Love the cam. Great power and torque in the 2-5K range. However, you will need a tune even with a mild cam. My car ran without a tune for about 10000 miles. Needless to say, it needed new plugs at that point. With the stock program, chances are the car will run too rich down low, and too lean up high. A good wide band tune makes a huge difference in unleashing the mods you have done to the engine.
The LT1 cam is not worth putting in, since it is not much different than the stock L98 cam that is in your car.
Crane 2032, or go to TPIS.com, look under L98 cams, they have a few that work great with an LB9, id also port out the plenum and consider aftermarket runners- TPIS< AS&M or SLP's. Youll be reving way higher with a decent cam in there. so opening up the intake will take better advantage of the new cam.
