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Old 05-21-2009, 10:25 AM   #109
Jim_PA
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Join Date: May 2005
Location: PA
Posts: 2,696
Re: 383 or 5.3?????????

Quote:
Originally Posted by discreet007 View Post
Just out of curiosity, Jim PA, do you agree with '72customdeluxe? For example 2 motors both making 400hp.

Again I am not a motor builder nor have I installed either of these motors in my truck, but I do have a genius level friend and we had a discussion a long time ago about the new LS motors. As I recall we were comparing why a motorcycle motor makes more power on less displacement and runs on pump gas. I think that was the convo, anyway, he said the problem was heat dissipation. The newer gen motors run way cooler therefore more efficient. I assume that will play into '72customdeluxe's statement. If I am wrong please chime in.
Yes, but I think you could make the mileage close enough that it shouldn't be a deciding factor. My build should be in the 390-400 range, and with an overdrive, I'm confident I could easily get 17-18 with it.

I also take into consideration that my 04 yukon has averaged 14.5 MPG over the last 4 or 5 tanks of gas. I've never seen more than 17-18 MPG on a highway trip with it. I realize it weighs about 800lbs more than my truck does.

I'm not anti LSx. I think it's a cool thing to do, and if 5 years ago when I started with nothing under the hood and had it been as economical and common as it is now, I would have considered it. But IMO, the entire requirements bill for an LSx swap over-complicates things, and would make back-yard tuning and diagnosing problems less more difficult than staying "old school"...
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