its easy to have 13-14 psi going though a 8.5:1 motor. The MP112 is way more efficient, hence the better than L RWHP numbers out of a RCSB 5.3 truck. You can run 14-15 psi on the 5.3 if you want to split the block into pieces.

There are many other variables in play, head flow, exhaust flow, Pulley size. Its not apples to apples here, we are talking about two different motors....Boost is a measurement of restriction, trust me the MP 112 moves a whole lot more air than the M112 on the L.


Maybe you should sell the Avalance and become Naked Lightning, Maybe YOU will be happier!

 

boost is not whats important here, it's used by magnuson for their kits as a reference because they have many hours of testing involved and can make a general statement that makes decent sense.

L's make more boost? haven't really seen that to be the case. If a 5.3 guy wanted to make 13-15psi on an MP112 he could, might take a crank pulley as well, like the L guys do.

 

I beg to differ.
all LIGHTNINGS have 5.4l
all COBRAS have 4.6l had one sold it I ran 14lbs.and bolt ons
what makes it easier to run more boost is crank pulley opt.=+2+4+6+8+10lb.of boost and thats just the crank pulleys.
chevy trucks have no opt.for crank pulley or else i be runin 16lbs.to
stock lightning boost 5.4l 8-10lb.
stock radix boost 5.3l 6-7lb.

Here's one example LIGHTNING with same mods as me needed a 100 shot of nitrous 16lbs. of boost stock eaton non ported to run 1 tenth and 1 mile an hour faster at the track vs no nitrous 9.5lbs. of boost 6.0l and he is one of so.cals fastest stock long block lightnings.

lightnings are just trucks that come with a blower from the factory chevys do not.

i do not fear any LIGHTNINGS with same mods with my rcsb.

 

here some data I found, stock L dyno'd at 346, add a 2.75 pulley = 355, add a 9" crank pulley (7.5" stock) = 415

BlownChevy is running a 3.2 pulley a putting down 445rwhp, ............this might indicate a more efficient blower, LSx engines have a 7.5" crank pulley as well.


L baseline 346rwhp

Change stock 3" (9.3psi) to 2.75" (11psi) for 9HP (355 vs. 346)

Add both 9" crank pulley with 2.75" for 15psi and 415HP

 

This makes me feel much better

Brian, you can run 13-15psi on a stock 5.3L.... With 6.0L heads on it

 

you can run it on the stock heads too, with race gas and a good tune.

My point was the stock 5.3 is 9.4:1 and the L is 8.5:1 or around there, hence the 14 psi of boost with no problems.

I think there are SOME members that like to stir the pot.

 

Behave.

 

Some more than others. LOL

 

Oh brother. Ask a question to stimulate conversation across platforms and all the old fanboys come out in full force. It looks like PerformanceTrucks.net is just the old LS1Tech/Trucks with a name change, in spite of what I remember Tony saying this site was supposed to be about.

Also, I could have sworn this was posted in the general TRUCK PERFORMANCE & GROUP DISCUSSION, not the GM section, but perhaps I just don't know how to read a web hierarchy.

If the compression on a Lightning is 8:1 or 8.5:1 then that would certainly explain it's ability to run more boost. That could even explain the entire thing for all I know. Or it could be pulleys. Or more efficient H/E. Or a combination of things. Who knows what the hell the reason is? That was the purpose for my posting here, to find out more information, information that perhaps we all could use.

My questions were asked out of ignorance - I know next to nothing about the L, only that I have seen a few of them run 12's and some 11's. I have yet to see a Radixed 5.3L dip that low, nor have I seen or heard of a Radixed anything running more than 10 psi. Has anyone seen a Radix run 13 psi? I'm curious...nothing more, nothing less. Unlike some, I have no real investment one way or the other.

I guess I'll just trade in my Avalanche, or crawl back into my hole and not stir the pot with any 'questions' that might challenge old ideas, or share knowledge across platforms.

 

I have an intercooled Radix on my 05 L33 that has produced less than the expected gains. It has 9.9:1 compression. Magnuson is working on it with me for sure. I'll have a full set of Tech2 diagnostic data sent to them this week.