Hey Everyone.

Ive got an LM7 In my iroc, and im looking to thump the power output in the ***.

Id like to do the 5.3L Turbo because, ive already got the engine (with only 5k miles on it), Not many people have done it, and id like to see what i can get out of the little motor.

That being said, im not sure if i should modify the motor any before i boost it.

Here's what im thinking:
241 Casting heads - Larger Valves & Larger chambers to lower compression
02+ LS6 Cam - Allow a little more air in

Already have an LS6 intake on it and a ported TB. Id rather put 243 casting heads on if its a good idea to lower the compression, but the 243 casting heads are expensive and will eat into my budget.

Im thinking a single Turbonetics T-76 or MPT70 Turbo, i know the 70 is cheaper, but im not sure if it will accomplish my 600rwhp goal. Im planning on using modified truck manifolds (Need to spin collector a bit & clearance the side of flange to clear the thirdgen subframe rails)

Ive fabricated a custom bumper bar to leave me lots of space upfront, would run a single Front mount intercooler.

All input greatly apreciated.

Thanks

 

The only thing I would change is the valve springs and cam (LS6). FI you want to change the heads go with 317's and drop the compression down even more.

I would opt. for a TC unit over the mp unit any day of the week. You should have no trouble making your goal either way though. The 5.3l is a bad little motor, I have been tuning a cam only 5.3l today with 13psi via a MP122, and it runs awesome.

 

Alright, so for heads, ill go 317 Casting.

Ill do some more research on the cam, and pick one out that will work well. Valve springs, i can change, no biggie.

Was thinking the .96 MPT70 Turbo cause its $625 new, so its a decent price, while the T-76 Turbonetics sell for about $800 - $1000 used.

I may opt for a MPT70 then run that for a season, and see how much i can get out of it before i upgrade to something larger.

I figure the 5.3L Block can handle a good HP number, so it would be fun to see how much HP i can get out of it with just a single turbo & the stock rotating assembly.

Im not sure what Wastegate or BOV im going to use yet, still determining that.

Im thinking around 12 - 15psi for the track, and run it at around 5psi on the street.

Sheldon

 

There has been at least one 5.3l that I know of to break 700 to the tires with the stock components in the bottom. I would opt. for the TC unit from the get go. For under a grand you can be into one and flying. Then down the road when you want to upgrade it you are only looking at about 3 bills to change the wheel size.

 

i was thinking of getting a mp70 for the kit i just bought. Don't. search on here and see how many issues those units have and the subpar customer service that backs them up. Just get the 1000 dollart76, its good to almost 800rwhp, 9's@140mph+ and has a proven history of being built tough with great customer service to boot, dont skimp on 300 bucks or itll come back and bite you in the ***

 

What heads are on it now? If its the ones that come with motor , is your compression not already 9.5-1 ? The 243 heads will drop you to 9.0-1, #241 heads to 8.5-1 and the #317 to 8.5-1. Is your motor built with after market pistons ? I think 500hp is the limit with stock pistons,give or take.

warren

 

Its a completely stock short block.

The N/A Limit is about 500hp, but FI brings in different forces so a FI Limit is much higher.

There was a guy last year who made 772rwhp with a stock '70s 150k mile truck shortblock

 

Sheldon, what transmission are you running behind that 5.3 in N/A form, also you said u have 3.73's, is it the stock rear end w/ a ring and pinion swap, and finally have you dynoed it and ran it down the 1/4 mi, if so what rwhp and what times did you run?
Thanks, Mike S

 

Pretty sure they stopped making MP turbos, I think they're using magnum now. That being said I'd go with a 76mm unit, itll be easier to reach your goals and when you need more you wont have to upgrade your Turbo. T70 will reach your goals but will be pushing it pretty hard.