Been making some changes to my old turbo kit so i thought id start a thread... I originally built this setup 4 years ago, i swapped in the 4l80e and 6l and added rod bolts, a mild cam, pushrods, and springs. I built the whole kit out of mild steel. It is an mpt70 with a 1.32 a/r twin scroll housing from a garret and an air water intercooler. System worked great but i wanted to upgrade some things as the steel was rusting and i've since aquired a tig welder. Number 1 was to ditch the k+n as i was getting sick of finding dirt in my intake track and i wanted a cold air intake as well. I also installed a proflo xt manifold and 60lb injectors as the old 42's were maxed. I wanted to use a bellmouth on the turbo but could not fit a big enough paper filter so i built an airbox ont the turbo with a 5" pipe over to the main airbox behind the front bumper which holds 2 factory paper filters and gets nice fresh cold air from up front. im gonna run no intercooler and water inj for now to see how it effects response as i usually run lower boost anyways. I also plan on upping the downpipe and tailpipe to 4".

Old setup:
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New setup so far:
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Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

Nice to see another truck on here.

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

I have a 1.32ar housing for my MPT70. I havent installed it yet, did it make a big difference?

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

i used to have a 3" cutout dumping in the fender, when it was open you could tell a big difference after the housing swap

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

I havent got my truck boosting yet, I just traded my big T6 for a MPT70 with a 68ar housing but the guy sent me a 1.32 housing with it. I just have to get a flange for the down pipe welded on. I have a 4 inch made for it already.

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

Nice work on the airbox.

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

thanks. Got it tuned pretty close today, Boost response is crazy fast! 1/3 throttle and it jumps to about 6psi around 2800 rpm. The intake makes it less jumpy on tip-in but the boost cuts in so quick it feels better when you lay into it. It keeps pulling harder and harder right till shift point though, makes me wish i had a forged bottom end so i could really let it rev! Highest IAT's i got was 68 deg Celsius on 8 psi with a run from 0-120 mph. I am having one problem though, it surges in between 1/4 and 3/4 throttle pretty bad. Im leaning toward BOV but im not sure yet. The BOV actually sounds normal now compared to fluttery on the old setup but it is hanging open at idle and the truck flutters at low throttle/high boost conditions....

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

Just my opinion, but you should upgrade to a 76mm Master Power. Even with that large housing I think the 6.0 is too mush for a 70. A 76 would help your surging problem, and push more air with less heat, which would really be helpful since youre not using an intercooler. Good job on that airbox, crafty!
Post a pic of the truck if you dont mind. Good luck!

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

Subscribing.

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

I know i need a bigger turbo, my budget is blown for a while now so im kinda stuck with what i got. Probably shouldve done the turbo instead of the intake but oh well! ill try and get some pics...

 

Re: 03 chevy k1500 6l, 4l80e, mpt70, pro-flo xt

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Swapping in comp 7679
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Still awaiting a v-band flange to build the 4" downpipe but i tried it out how it is - boost comes in quicker but smoother than the t70 and it seems to pull a bit harder, my a/f never really changed much though. Now im back to the bov blowing open all the time in part throttle, making it surge and act weird - i have a much heavier spring and shims in it, guess ill try and find a heavier one yet...

 

well I finally got around to re-doing my exhaust this weekend. I divorced the wastegate and it now dumps in the fender and built a madrel bent 4" exhaust with a straight thru muffler. Good news is the response is incredible, sound is barely louder than before, leaned my mapping out, and it gained 2.5 psi boost under 4500 rpm! Bad news is anything over 4500 rpm i can't control the boost anymore, it runs 9 psi and then climbed to 13 before i let out each time. I dont think the wastegate is too small (50mm JGS if i remember right) so i dunno whats going on?

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