Scream

iTrader: (6)

If it were my truck, I'd put in a 402 or 408 stroker. Maybe with a TR224 cam? Mine's very streetable even in a stock CID LS1, and makes plenty of low end torque (but remember I came from a 4.8, so my views might be a little skewed. )

LS1S10

What kinda gas mileage are you guys getting with the Radix chargers? If i go the supercharger route, i wanna keep the bottom end of the 5.3 stock but maybe change the cam to try and get more low end outta the s/c. Personally i just dont see building the bottom end on a 5.3.....if im gonna crack something open i'll just get a stroker. I would go for the STS kit because i've heard of alot of people saying the low end is huge because a turbo builds full boost so low in the rpm range. But seeing how i just went through hell to put headers on my truck.....rendering them basically useless over the stock manifolds is something i dont wanna do.

A 402 is a stroked 6.0 for the guy asking if it was a 5.3. I didnt really think about gas mileage with the 402.....now im kinda shuddering at even the thought. I'm getting about 12 mpg city with my truck now....so with a 402 it would probably be more like 8 mpg I'll go check out the dynometer archives and see if i can find some posts with 5.3's with radix's. Anybody think that about 450 ft. lbs is doable with a Radix on a 5.3 and a different cam? Also, would doing anything with the stock 5.3 heads affect low end at all...i dont want to go through the extra expense if it's not going to boost low end. I'm looking for my peak torque to come in at about 3000-3500 rpm because im also looking at using a Yank Truck Thruster converter with the built 4L80E.

BTW, just wondering and i hope someone doesn't see this as a ricey type question. But how loud is the Radix charger? I've got my 6-71 on my Z-28 on 1:1 drive and it friggin screams at high rpm.......and i've kinda grown to love it that way.

zippy

i'd go with the 402. with something that heavy you'll be in the boost alot anyway which will make fuel milage about the same and getting the 402 leaves room for future mods.

Mr. Sandog

I wish I would have done a motor first. The blower is okay, but with this heavy beast (6,000 lbs) I think a stroker would have done a much better job of giving me what I originally wanted.

moregrip

iTrader: (8)

ah fooey! you've got some camming and tuning yet to do my friend

BlownChevy

iTrader: (20)

I am getting 22-20 on the highway and about 17-15 on the street.

LS1S10

Sounds good, maybe i'll stay in the same area of abuot 12-14 mpg city and 18-20 hwy.

Still though, what about how loud it is and is 450+ ft. lbs. doable on a radix 5.3 with a small cam and tuning on the stock bottom end? I can't find anything dyno wise on a 5.3 with a Radix.

BTW guys, i got DD '03 and i know its not accurate for Gen III motors on high rpm....but i've heard its pretty close on low rpm. What should i plug in for CFM? And what would better simulate our FI system....sequential fire or Tuned Port?

LS1S10

I just ran a combo on DD '03 using a 4" bore and 4" stroke with 11:1 comp, and old school AFR 195 heads, they flow fairly similar to 6.0's. Plugged 800 cfm in with using sequential fire injection? and a comp XR259HR installed straight up. And i think what i got is probably really innacurate but im getting a peak of 508 ft. lbs at 3500 with 415 hp at 5000. The torque curve is a decent shape with 462 ft. lbs at 2000 and it stays above 400 till 5000 rpm with 436 ft. lbs and drops to 380 ft. lbs at 5500. This sound bout right to you guys or is this thing WAY off?

Any of you think i should try a larger cam and advance it some to lower the rpm range? I was expecting to see these kinda numbers to the rear wheels with a 402 stroker combo setup this way.

Mr. Sandog

You've got the 285 HP 5300 Vortec, so you'd dyno at about 240 RWHP/260RWTQ. Add 100RWHP/100RWTQ or so for the Radix and you're at 340RWHP/360RWTQ. You're asking for about 90 more HP/TQ more from a cam and a tune. I guess it's possible, but not likely, unless you seriously sacrifice some driveability and power below 3,000 RPM's, which you say you want to keep.

Another alternative is if you do the heads, too. Then you'd have to shrink the pulley to keep the same boost, due to increased flow from the better heads. I dunno, I think you're pushing it, asking for 450+ ft/lbs from a 5.3L.

At this point you're in it for $5K for the radix, $1.5K for the heads, $400+ for the cam and springs, $300+ for the tune....how much was that 402 again?

LS1S10

Yeah, i've kinda thought about all that and i guess the 402 would be a better way to go. $3500 for the shortblock and about 1,500 to 2K for heads fully prepped with springs. I guess about 1,000 for cam, pushrods, lifters and rockers. And the rest of the stuff i can reuse of my 5.3. So basically it would come out to be right around the same as the Radix, with the added benefit of having a fresh motor with a forged bottom end for future mods. And i would still be able to tell people....oh its just a 5.3 with minor bolt on's

Only other question i would ask would have to be....will a 402 stroker pass emissions with a small cam and still using the cats and EGR system? We dont have emissions here yet, but i wouldnt doubt within the next couple of years will have the same kinda restrictions that Atlanta has. I don't know exactly what all they test for in Atlanta.....but im hoping it isnt like California emissions.