More I think about it, a chassis and engine dyno probably aren’t the best comparison. The engine dyno is always going to show more. So I’m eating crow on the 1st sentence of my last post.

I would like to see a comparison of a ‘square port’ cam in a cathedral port head/engine combo. And then swap on either a ported head, better head (stock 243), or an aftermarket head. Seems odd that Comp shelf cam that works on a square port, but doesn’t work in a cathedral. I understand how it might work better in a square rather than a cathedral, but I’d find it hard to believe that the most powerful square port cam isn’t going to shine in a cathedral.

 

All the cams I posted are square port cams run on a cathedral port head 5.3. They tend to make more power later in the RPM range and be more peaky up top with less average power across the board. Good for dyno queens and turbo guys that want to limit power down low and pour it on up top.

I also have a hard time believing a basic cam only 5.3 with headers is making 470+ HP . I don't see the VE being that high on that setup. But I do believe it's a great tool to see which camshaft performs the highest VS the other cams tested. And I've seen ALOT tested by those 2 dynos/companies. So regardless of what the actual power is... those 4 I listed were basically on top for "stock" 5.3's.

So my plan is to run some huge twins, keep the back pressure at 1:1 and basically run an "NA" cam with a turbo combo. Should produce great numbers per pound. unfortunately I don't have room for an intercooler to really see what the setup is capable of.

 

what sort of rpm would be safer to drop too ? would you recomend revving gen3 stuff this high as long as springs , trunion upgrade etc ?

 

Its always a balancing act, esp with a gen 3. Too much power load down low bends the rods, too much RPM spins bearings, is hard on valvetrain, and eventually over stresses the bottom end due to excessive RPM. Id have zero issues buzzling a gen3 small bore motor around 7300ish with a good spring kit and push rod on factory rockers/lifters (assuming they are in good shape.)

 

I’ve been following some similar comments of yours and wondering what I push my 5.3 to once it’s going with a s475. I was thinking shifting 6800 and limiter at 7000.

 

That's the range I intend to be in. It's a safe number on a JY build. AFAIC whether it a Gen 3 or not, why put the wood to it much below 5K? My goal is to get my tune and converter to get the RPM's over 5K as fast as possible, then let the boost do the work.

I know this isn't what everyone does, but it definitley keeps the rods in the block as long as the timing is sensible.

 

I agree. Defiantly the way to setup a most drag builds.

 

Mine will be mostly street and hoping to keep power around 550whp until I can get a forged bottom end together and a stronger tranny. Any concerns at this power level with torque coming on around the 5000rpm range for peak and I would assume 500ft/lbs? 5.3 and a s475

 

Thats pretty standard, just keep timign softish in that range. *should* be ok IMO.

 

I really get a good chuckle every time I put my stock 5.3 in an et calculator=400hp every time LOL

 

What's your Et/mph, and weight? I have a ls1 camaro, with bolt ons (headers, exhaust, Cai, gears, and a good converter) that will run 12.40's on a good day at 109. The calculators say 370-380, and it wheel dyno'd at 300 hp with the power steering bypassed, so I'd say it's pretty accurate.

 

I have acquired a China knockoff S475 for free. It was on a truck and the story is someone lost a wrench or socket while changing the air filter and , ummmm, the compressor wheel and housing took some abuse (they’re junk). The turbine and bearing feel good/ tight.

I found a new wheel and housing for less than $235 on eBay, but then it occurred that I could put in an 80mm compressor and housing and convert this to an S480. Anyone ever done this? Is it possible?

 

It's possible, many of the 480's are just an 80mm wheel with a 75 cover machined to fit. My concern would be balancing, many of the knock offs are balanced via the compressor nut vs the wheel itself, and i'm not sure how well they're component balanced. If you expect it to live, i'd definitely consider getting it balanced with either wheel.

 

Who does that?

 

Typically most diesel injection, and turbo shops, or anyone that rebuilds turbos. If you knew everything was component balanced, some just assemble, and run them, but with knock offs, it's a crapshoot for sure.

 

So then would it be worth ramping in timing or boost with higher rpm , maybe ramp in another 2 psi from 6300-7300 ?

 

s475 covers modified for 80mm wheels dont gain much.
The big gain is the combo of the borg 80mm wheel and race cover which actually comes standard on a s480

 

My understanding is that the race cover adds to either wheel, but I gotta believe that the wheel change alone is worth a decent amount. It was a common upgrade from many different reputable turbo shops. Is there any actual flow info out there?

 

Yes. The t6 S480 is an actual production unit with compressor maps. It outflow the 75 comp wheel by quite a bit... and thats with the non-race cover. Having run them both (without race covers) I can tell you the 80 makes quite a bit more steam.

Also not sure you can just hog out the inducer of a 75mm cover to 80mm and go? The exducer of the 80mm is 10mm larger as well... believe they are 75/100 and 80/110

 

I want to re-ask, can I put the S480 compressor wheel and S480 cover onto my China S475 that I acquired (in post #52)?