Hey guys, i swapped a 5.3 LM7 with a t56 into my 86 base sport coupe. Car was an original 2.8 automatic car. Its going to the dyno on monday for a tune, but the suspense is killing me. Here is the setup:

2003 lm7 5.3 from a silverado, 87,000 miles
T56 trans, stock clutch and flywheel.
Stock 5.3 heads, 1999 .500 lift ls1 cam
Ls6 intake and injectors.
Stock manifolds with 3 inch piping, no ncats.

Right now the engine is running on a stock 5.7 ls1 computer and harness, with just a tune adjustment for the ls6 injectors. Has plenty of power even though its a 5.3, running with a 5.7 tune.

Im just curious around what rhwhp my combo is making, or is going to make after the tune. Just an estimate would be awesome. She feels strong now, so im wondering what difference the tune is going to make.

 

am interested in your dyno numbers , you gonna post them in this thread ? asking because of my swap , a 03, lm7 ,stock, just 1 3/4'' headers/2 1/2'' exh. for now.( I am gonna get a better tune upon completion.)

 

I say 310hp 325tq.I have a 05 5.3 super victor 4150tb and 1 7/8 headers

 

I think you should be just over the 300rwhp mark and 320tq also.Dont know what you have for rearend and gears.Still a nice setup though Ill be first to say the stock manifolds need to go lol.Look into the racing innovations lt's swap headers for a very budget minded 1 5/8 with 3" collector. Im leaving quite abit of power on the table from the manifolds.This is what ill be putting on shortly and retune..better than stock manifolds.

And as for the suspense..I couldnt sleep the night before lol.I kept going over the car making sure everything was good to go...and sadly on the dyno last time we quickly found out it wasnt.

 

Im gonna say 270 rwhp (hope I'm wrong and you get over 300 though), really interested to see what it puts down as I have a similar setup up. Stock 5.3/t56 with 862 heads with just a 212/218 Comp cam and long tube headers.

 

My vote: 310hp and 310lbft. My SWAG is based on:

-T56 (less HP loss on dyno)

-Carcraft cam test:
http://www.carcraft.com/techarticles...st_comparison/

-I am with everyone else, the manifolds are holding back the power and will really choke the motor if you start upgrading the motor (cam,tune, nitrous etc...)

I am interested in the results, I have an all stock 2001 5.3 running a 750 Demon with 1 7/8 headers. I have not had it on a dyno, but based on quarter mile times it should be pushing around 275hp to the wheels.

I'm in for results! Good luck!

 

updates?

 

 

Either it didnt make it to the dyno for some reason,or you ran it and dont want to post the results lol.

 

Lol sorry guys, been busy and never even new i got so many replies on this thread. sic7camaro was just about right on the money.

It made 308rwhp and 323rwtq. Im really happy with it. i was expecting around 280 rwhp, considering I'm using stock manifolds, and all i did was add a 40 buck .500 ls1 cam and an ls6 intake plus the tune, pretty much all stock bolt ons. I also found out my injectors are actually LS1 injectors, and not LS6 though. The tuner said i could probably get another 30 rwhp with long tubes, so I'm looking for those now. Plus spring is right around the corner and i really want to get the ac working, but i can't find ac lines that fit with manifolds. Also the only long tubes i seem to find are the hawks "budget" long tubes, but they want freakin' 700 bucks for them!

Heres the sheet:

 

Heres a shot of the setup and the first run on the dyno. He couldn't even do a full run because it went so lean. Guy i got the pcm from had it tuned for ls6 injectors, which i thought i had.

 

As I mentioned earlier. Racinginnovations sells longtube headers 1 5/8 for our cars polished for $250. They aren't the greatest set of headers but its better than stock. Im putting on a set tomorrow with a 3 inch cutout with a 3 inch y pipe.

 

Thanks i just found them online for 275.00. Im using a modified hawks long tube y pipe with my manifolds, so i should get them to bolt up pretty easy. Just have to remove the sections i made going from the y pipe to the manifolds. For 400 bucks less than hawks, ill take the risk as far as quality. Have to be better than the stock 60 buck manifolds I'm running now. Plus i can easily have ac then.

 

I win.

 

Ill let you know how well they fit tomorrow and if i notice any increase in power without being retuned.

 

Ok well to keep you informed.The headers fit well.No effort to install,I recommend buying much thicker gaskets though as I had some header leaks with the flange not being 100% flat.The driver side o2 sensor wires are extremely close to the header so make sure you shield everything you can in that area.otherwise everything else was great,my car definitely wanted to breathe alot more,having the cutout is awesome.

 

Awesome, glad they fit well. Gonna order a set myself now. Is the exhaust any louder with the longtubes than your previous headers?

 

Yes...and no lol. It made the rest of my exhaust much deeper tone which is quieter at idle.Wot is slightly louder but then again I had alot of leaks in my previous setup which made the car loud in a bad way.

 

Lol thats good. I have a magnaflow set up that I'm using from when i had the carb'd 355 in the car. 3 inch all the way back with 3.5 tips. Pretty much stock at idle, but it roars the more you put your foot into it. My car is pretty much a base model, so i want to keep it sleeper sounding. Probably gonna order them next week, ill post a clip when there in.

 

mine is the same magnaflow cat back in 3 inch.Should should exactly like mine..not as lopey depending on the cam