If I have a set of LE2 heads is it better to have an LT4 intake with a 58mm throttle body or a regular intake with a 58mm throttle body.Im curious because im about to do another engine build and I want to have some professionals give me some real good tips. I already have to block bored over 40 with slp pistions, I ordered the LT4 Hotcam set for my heads, but what else is needed.Also what type pound of injectors to use because stock just won't cut it.

 

I believe this is in the wrong section, but I'll go with it.

An LT4 intake will not fit on LT1 heads, use your stock one. LT4 cam seems a bit wimpy for an LE2 setup, unless you're trying to pass emissions or something. What is your power goal? Drive ability goal? What tranny are you using? With injectors, most people say go big or go home. You can run 60lb injectors on a stock motor as long as it is tuned properly for it. Spend the extra cash and get a larger injector than you need so you have room for improvement. Otherwise you'll be one of 87 people trying to get rid of a 30lb set when you find out they aren't enough.

Also, make a sig with what car you're working with so people know how to better answer your questions. People will also be more likely to respond.

 

As-cast, the LT4 intake manifold runners are no different than the LT1 intake, so putting an LT4 intake on the LE2 wouldn't make any sense, unless the LT4 intake was ported to match the LE2 heads. Then there's the problem mentioned above - the LT4 intake has more meat at the top of the runners, and that interferes with the vavle cover rail on the LT1 heads. The intake has to be machined for clearance. Really makes no sense at all to put an LT4 intake on your heads. Either the LT1 intake or the LT4 intake will need to have the throttle bore holes opened up from 52mm to 58mm to realize any benefit from a 58mm throttle body.

To get your minimum recommended injector size, multiply the engine's estimated flywheel HP X 0.07...... example:

500 flywheel HP x 0.07 = 35 #/HR minimum injector size.

The stock LT1 PCM will work well with 42 #/HR injectors, so that's probably a rational upper limit.