Silver_Whistler

I bought a motor over ebay about nine months ago to build up. Its done and in the truck. I was told that it was a 5.3, but after my recent trip to the dyno, i am beginning to believe elsewise. Heres a list of my mods.

Ported and polished heads(stockk valve size)
MTI Hammer cam 222/222 .566/.566 112lsa
Asp pulleys
Long tube headers no cats
ported throttle body and MAF sensor
Built 4l60e 3200 stall convertor

A/F ratio ranges from 13:1-13:4 throughout the pull.
I pulled it up to 6700 rpms and my maximum numbers i could pull out of the thing was 312hp and 315tq! What the hell is going on?!?
How can i tell if this motor is indeed a 5.3 or a 4.8?

conan

iTrader: (5)

Take the trans off and look at the top pass side where the the bell bolts to the moter the L# is in the casting.

roadrash9r

iTrader: (2)

not sure there is a way to tell. the 5.3 and 4.8 blocks are the same thing. I think stroke is the only difference. Might be bore but I thought it was stroke. Also my budy has a z06 cam, gibson exhaust, shorty headers, cold air intake and a powerdyne supercharger on a 00 silverado and only made 327hp and 367tq, so your numbers actually look pretty good for a heads and cam 5.3. Your intake is really restrictive and the valves in 5.3 heads are tiny. So I think you did pretty good.

Silver_Whistler

Are you meaning the L# as in LM7 or something like that?

conan

iTrader: (5)

No it will say 5.7L or 6.0L 5.3L ect Its part of the casting of the block.

Silver_Whistler

I saw those numbers before i put the thing in, but it says 4.8L/5.3L on the block. Since they both use the same exact block. just a bigger stroke on the 5.3L

conan

iTrader: (5)

Are the heads 5.3L?

Silver_Whistler

hey use the same heads as well

roadrash9r

iTrader: (2)

man im telling you that you put down good numbers. Dont go off all the ls1 guys that have better heads intakes ect. 312 out of a 5.3 NA is good. Stock is 240 maybe, so you gained 72whp over stock with your mods. Thats like 100hp at the motor.

roadrash9r

iTrader: (2)

and your getting these numbers through an auto and a loose converter. Good numbers, my budy is pissed that you got that all motor and he has all bolt ons and a charger and only made 14 more whp. I really think the stock valves and intake limit it.

Silver_Whistler

Yes that is true that they are good numbers, but i see guys making 340+ with stock heads an a TR220 cam. everything else is the same. There is a guy with a 5.3 with a smaller cam than me with ported heads putting down almost 380 horse. I just want to know what the hell is going on with mine. There are however guys putting down around the same numbers as me with 4.8 motors.

Bryan @ Speed Inc.

iTrader: (19)

truck intakes suck, the cam isn't that big, and you're going through an a4 w/ a 3200 stall. those rwhp numbers aren't too bad for what it is.

Silver_Whistler

I read in ChevyHighPerformance when they did a power comparison of the different intakes. LS1, LS6, and the truck intake. It turned out that the truck intake made more power than the LS1 intake but only like two horsepower than the LS6 intake.

roadrash9r

iTrader: (2)

what kind of correction are they using on the dyno? SAE is the most accurate but will be 10-15hp lower than STD correction. And STD is probably what they are posting. Plus dont believe everything you see on forums. Does it feel alot faster than before? It should. Id be willing to bet that the 340hp would run neck to neck with you. All dynos read different.

Silver_Whistler

Same dyno, STD is what it is and the guy with 340 horse is running a 12.85 at the track, I run a 14.1.

roadrash9r

iTrader: (2)

than what mods does he have that you dont. Be it cam specs dual exhaust, tire size, gear ratio ect. What kind of 60 ft times? thats a big difference in E.T for 28hp. figure 10hp is a 10th or so. Maybe a little more at the wheels.

Silver_Whistler

His mods are as follows.
TR220 cam 220/220 .551/.551 112 lsa
asp pulleys
long tube headers
3.73 gears(same as me)
1.7 sixty foot times for him. he has a 3000 stall, mines a 3200
his is an auto RCSB chevy

roadrash9r

iTrader: (2)

the cam size is too close so I cant see it being that much of a difference, it could help that his is smaller, but shouldnt give him better peak hp. Who ported your heads? Maybe they ported them wrong. If the intake runner is really smooth you will get a bad burn. It needs to be "rough" to cause the air to swirl so the fuel atomizes better. Also if you went with a hogged out port you probably lost velocity and lost power. Your 5.3 intake and small bore cylinders dont need huge heads. My ls6 heads have bigger ports than my afrs but my afrs made more power. Im thinking the heads are to "big" for the motor.

Silver_Whistler

One quick question, How much power do you think im losing or not reading on the dyno when the convertor is unlocked?
All of my pulls were made with the convertor unlocked. I just now remembered that.

roadrash9r

iTrader: (2)

Depends, Ive heard quite a bit. Especialy since your peak HP isnt at 6700rpm. If its more like 5800 you could be loosing some. What rpm does your stall flash to when you stomp it in 2nd or 3rd? Also if your truck is heavier than his your stall will actually go UP! So the heavier the truck, the higher the engine torque, and the numericaly lower the gear ration say 3.10s the higher the stall will be due to the extra load on it. So your 3200 might be 3800-4000 depending on these variables. And yes you are loosing horsepower on the dyno from an unlocked converter.