Why 3 bar? 2 should get you where you need to go IMO. Do you have the software yourself? If not you're going to have to shell out the bucks to get tuned. Gotta pay to play.... I'd hate to see you post up in a week or so about leaning this one out and smoking some pistons and/or rings.... Get it tuned right and be done with it.


As far as the heads go, with boost the flow difference will not be enough to worry about since the air is pressurized behind the valve. Out of boost you're going to most likely want the throttle response and tq from a little bump in compression. I would personally run the 5.3's and keep it around 10psi or less and keep good fuel and a good tune-up in it. The 6L heads will lower your compression ratio, but they do flow better. I had CNCd 317 heads on my 347 ci turbo build (3.905" bore) and it felt pretty soggy out of boost because the lack of velocity, but once the boost came in... You better be holding onto something.

 

Anyone have any suggestions for a good tuner. I live in southern Illinois and don't wanna run my new motor a lot without being tuned first

 

If your going to be replacing the head gaskets when you do the studs run a LS9 gasket. A freind of mine has been running 20# on a stock 5.3 in his rx7 and never blows a gasket.

 

should hold 8 psi pretty easy. heck my last lq4 ran on 13psi stock for a very long time. lower comp then the lq9.

 

I am curious about flexplate issues. What flexplate do I need is there a spacer needed I am running a 4l60 trans. I have heard that u need a diff flexplate so I wanna order what I need so I don't have to mess with it next weekend.

 

If you got a 6.0 with the flex plate on it it may have the spacer on it unless there was a 4l80 behind it. I think the crank part num was 216 and it had a diff flange thickness. The lq9 i had came from the factory that way so they didnt have to have different converters. The spacer was on it and has the longer bolts as well. Hope this helps.

 

Y’all are making me confused and I know the answer. The short answer is, early (’99 & ’00) 6.0L’s & 4.8L’s equipped with the 5-speed manual transmission had a wide 1.250˝ rear crank flange in order to work with the older style transmissions such as the 4L80e, while later 6.0L’s were equipped with a crank that had the typical narrow .857˝ rear flange like all the other LS style engines to work with the newer style 4L60/65e. So when anyone uses a short crank Gen III/IV with a 4L80e or any of the transmissions designed for pre LS type engines, you will need to use the crank spacer and longer bolts like the General did or you could have a hybrid torque converter built to make up for the difference in length of the two cranks. In either case, you will need to use the matching flexplate or flywheel with the components your using, so in your case just use the flexplate from your 5.3L.

 

Thanks. So this is an 02 6.0 and it was in front of an 80e so I should just use my 5.3 flexplate?

 

Yes, just pull off the flexplate and spacer from the 6.0L and install your 5.3L's flexplate, using the shorter flexplate bolts from your 5.3L as well and you will be golden.

Also, if you look at the picture above of the spacer, you will notice that it has two additional bolt holes that are threaded. These bolt holes are there so that you can install a couple of longer bolts in them to force the spacer off the back of the crank if in case it doesn’t just come off by hand.

 

ive got a buddy from sikeston mo that has hptuners. hes got a front mount ls1 that he built and tuned in a 90 body style long wheel base work truck its a true sleeper! im sure he'd be happy to help you out and build you a tune. but i do belive you'd have to buy some credits. he raced his work truck at bowling green ky at the lsfest. there is a small article in the gm high tech magazine. i can give him a call if you'd like or pm you his number. we are just across the river.