TURBHOE

iTrader: (4)

who all runs -4 feed lines still? i thought people were having to put in restrictors due to over oiling the turbo with -4 lines. i run a -3 myself. and a 38mm wastegate at a solid 10psi off the spring. my oil return is in the front also.

1slow01Z71

iTrader: (36)

Honestly IMO, a motor swap is easier than a head swap. You are correct lower CR will allow more timing/boost but what percentage are you actually in boost? <1% Id bet. Your out of boost mileage is what Id be more worried about, guys with 408s running high 8:1 CRs are getting horrid mileage and theyve got a 4" crank making a lot more TQ than that 5.3 ever thought about. Youre also forgetting that you have to pull the power steering/alt bracket, youre going to need new head gaskets and bolts which will run you 120 along with a minimum charge of 150 to mill heads, hell youre almost half way to an LQ4. Why doctor up that high mileage of a motor? With a bigger motor youll just shift earlier. Hell Wilde Racing ran 11.4@119 with a 67mm, from the sounds of it youre not look for anythign close to that so Id say youre in pretty good shape for an instant boost fun truck with a larger motor one day.

In the end youre going to do what you want but if it was me I wouldnt mess with it at all and save my time and effort for a bigger lower mileage motor.

01midmetws6

iTrader: (1)

Your EVIL!! Everything that you stated is completely true. When I bought this truck I promised the GF it would stay "Stock" (bolt-ons and tuned only). I do not want to let this one get out of control and want to stay with an 4L60. Now my mind is wandering again. I keep telling myself just put in a LQ4 and stay with a low boost setup but I know after I get going I will max out the little turbo and be looking for more.

I think at this point I will see what happens with the manifold bolts when I pull the passenger exhaust manifolds. If anything breaks I will go with the 241's if it comes apart I will stick with the stock 5.3's. I will swap the cam because the water pump gaskets are seeping anyway.

Thanks for the input, we'll see what happens. This things will be done end of the month just don't know how it is going to happen yet

La Tu Papi

use 241s it will put you at 8.8scr, youll benefit from the 2" intake valve, with using those heads to lower compression youll be able to run more boost which is more power. As for some stating power off boost well you have a 62mm turbo? that will be near full spool before 3k more like 2500 which off boost you wont notice all that and off boost youll only be losing roughly 30 hp which isnt much but youll gain a **** load on boost.

as for your 42s theyll be fine for your combo, its only when you decide to want more from your combo is when you need to upgrade

38mm gate is going to be fine for a 62mm turbo

IAT an fbody one with its plug and gromelet is all you need, you wont have issues with this if you make the hole a little snug in the charge pipe. It wont leak or anything if done right.

1slow01Z71

iTrader: (36)

Youre not in boost while cruising down the highway, thats where your mileage suffers with a low CR motor, ask any of the low compression guys running around their gas mileage sucks. A 62mm turbo is goign to be out of breathe at 12ish psi anyway on a 5.3, how much do you hoenstly think hes going to gain by dropping .7 on CR? Either way he drops CR and ups the boost/timing, hes still putting a lot more stress on an old shortblock.

La Tu Papi

do you have actual turbo vehicle experience powered by a GAS motor? If tune is correct gas mileage wont suffer while cruising highway.

also mileage doesnt mean squat for a motor. Its how its been abused, you can have high miles thats lived nothing but highway duty, you could have a low mileage motor thats been rung to hell and back. As long as the motor has solid compression, good leak down percentage, good oil pressure and no noises. Id boost/spray/rev any mileage motor as long as it checked out fine.

As for him dropping down .7cr its actually one hell of a difference for increased boost levels. Typically you gain 22-30 rwhp for every psi, for every .5 in CR you gain or lose 15-20 hp. Dropping .7cr will allow you to typically run 4-6 psi more. That is easily a gain of 100 rwhp.

LsxCody

iTrader: (3)

i run 317s on my truck to lower my comp. and i still get good mileage.if you already have the heads throw em on there. op said he was on a budget and didnt wanna buy another motor so i dont think he wants to swap a 6 litre in there.

TURBHOE

iTrader: (4)

i have ls6 heads on mine. they were port and polished. mileage and off boost feel is the same but in boost its way better. i have boost anytime over 30% throttle with the tcc locked up. and getting up to speed from zero to 55 its hard to keep out of boost. its takes a very light foot. although i do have a heavy truck.

01midmetws6

iTrader: (1)

Update > I had a women take a right turn in from of me on friday morning and now the truck is getting an HD front. I tore the front off of it yesterday along with the fan/shroud, intake and airbox and egr/tubing to allow for a good pressure wash and inspection. Upon inspection I found one bolt broken off on both manifolds. That means the 241's are definitely going on. I will have them milled cleaned up so they should bring compression into that 9.1-9.2 range. I like the idea of being able to safely run 11-12 psi on the lower compression motor and feel that with the 62 it will be in boost more than out.

I finished up ordering everything I need to do the swap this upcoming weekend and should have the new front with valances finished by about Thursday. Man its going to be another busy week.

Here are some pics of the car that pulled out in front of me and my truck. She had her 2 year old in a car seat placed in the right rear. Luckily for both of us no one got hurt

1989k1500

iTrader: (23)

You can safely run 12psi on a 10:1 motor with pump gas and a stock cam. You dont need 6:1 compression to run over 10lbs of boost like some of the people on here seem to think.