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i just finished my turbo 5.3 build and i'm a little disappointed at the numbers.
the motor is a bone stock and when i say bone stock i mean i didn't do anything to the motor. accept for cooler spark plugs.
the motor is a 2003 yukon motor and i'm still running the truck intake.
the turbo is a gt45 ebay deep .63 ar on the compressor housing 1.05 ar on the exhaust housing.
the tuner sed i need a cam but before i ask bout that i'm gonna go into a little about how she acted on the dyno.
so i have a 30 psi ball and spring boost controller on it and a 15 lb spring in the wastegate. with the boost controller set as low as it goes it makes 10 lbs when loaded at a constant 3500 rpms. however when we made a pull the turbo spooled at around 3300 rpms which i expected but it only made 7 lbs of boost at 6000 rpms. I dont know what it is but i cant understand why i'm only making 7 psi of boost when we make a pull but when it's loaded at 3500 it makes 10.
the numbers are 315 RWHP and 320 LB FT
what cam do you guys suggest i switch to and why do you think it's being such a lazy dog.
Need some more info and some pics of your set up would help.
Are you running a IC ? If so what size IC ?
What dia. is your exhaust ? How long ? Any mufflers ?
How about fuel system ? Pump size ? Inj. size ?
What computer ? Stock or aftermarket ?
How much timing? What tranny ?
The more info the better.
But ya... Those numbers are way low for that turbo on that engine.
yes i'm running an IC it's a 8x4x20 inch air to air
the trans is a full manual th350 with a 2800 stall convertor
80 lb injectors and a wellborw pump 300 LPH
i have 2.5 in mandrel bends into a single 3 inch pipe going to the turbo and a 3.5 inch piece about 10 inches long coming out of the fender
also running the stock computer with HP tuners.
i'm not sure how much timing
as far as the wastegate goes it is an ebay knock off so their is no way to set preload on the spring so it has a 15 lb spring on it but it starts to open right around 5 lbs hence the reason for the boost controler.
i know the biggest limiting factor is my cam it is a bone stock motor with a 191/190 .457/.466 114lsa it's rather on the small side for even a NA motor so i didnt know if that was the only thing i should change or if there is something else
i know the biggest limiting factor is my cam it is a bone stock motor with a 191/190 .457/.466 114lsa it's rather on the small side for even a NA motor so i didnt know if that was the only thing i should change or if there is something else
Guys have ran 9s on the stock truck cam. I wouldnt point the finger at it.
so what do you think the problem could be i know the BOV isn't opening until i get off the throttle and the wastegate well it is a pos but right now it wont even start to open until about 4500 to 5000 rpms
With a 15 PSI spring and a ball and spring boost controller, your wastegate shouldn't have any chance of opening that early. Tighten up the boost controller, then make sure your wastegate lines are plumbed in right.
You're down about 100-125 HP from where you should be with 10 lbs on a stock 5.3 with that turbo. You have a gremlin to chase down.
I would be sure 100% there are no leaks pre turbo. My setup is a bone stock 5.3L, LS6 cam LS1 intake and even with a 3600 stall I see positive pressure really quick just rolling into it. I have only driven around my block. But this weekend I should get out for a few rips.
I would make sure that ebay gate isnt leaking internal or the seat isnt sealing.
that is another good question i'm not sure about what side of the seat should go up against the valve on the wastegate i'm not 100% sure i put it together right
You don't need a cam... and if your "tuner" told you that., get a new tuner. You should grab some PAC1218 valve springs or similar IMO.
What does going a bit lean mean? Got an AFR value?
The seat going towards the WG valve should only go one way. it should physically touch the WG valve and seal 100%. With the engine idling put your hand under the WG exit. Can you feel any exhaust coming out?
Smoke test is crap IMO. Make a plug for the turbo inlet and put 20+lbs of shop air into the sytem. Then spray it all down with soapy water.
I like to use a shop air fitting instead of a tire valve.
You don't need a cam... and if your "tuner" told you that., get a new tuner. You should grab some PAC1218 valve springs or similar IMO.
What does going a bit lean mean? Got an AFR value?
The seat going towards the WG valve should only go one way. it should physically touch the WG valve and seal 100%. With the engine idling put your hand under the WG exit. Can you feel any exhaust coming out?
Smoke test is crap IMO. Make a plug for the turbo inlet and put 20+lbs of shop air into the sytem. Then spray it all down with soapy water.
I like to use a shop air fitting instead of a tire valve.
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Interesting! So would you just plug it off on the other end by the throttle body or pressurize the intake as well? I guess you could take all the rockers off and so long as no valves are bent/shot the intake should hold air also right?
06-17-2015, 09:23 AM
Turbo 5.3 laggy spool 
