jatwood

im building a turbo 5.3 single cam,springs,headwork,and push rods is there im going to tune it around 750 80lbs injectors is there anything else I need to do ? Do I need to do any thing to the bottom end ?

vettewreck

iTrader: (1)

From the research I've been doing (I'm new to the boosted 5.3 as well) it seems the bottom end is fine up to maybe 15lbs to be safe. Even though there are PLENTY of guys running 20+lbs of boost and seem to be running fine. Just depends on how hard you're going to be on the motor. Weekend warrior or race car at the track, ect, all come into play.

Im building a forged pistons and rods in my 5.3 to be safe bc I want to run 20lbs of boost and be safe around town and the occasional track pass.

Twin turbo c5

I've never messed anything up on the bottom end I've either blown head gaskets or bent rods because of water In the cylinder. It all depends on your budget and what your trying to accomplish I say run it stock me and plenty others have had goodluck even on high boost.

HexenLord

Power is not measured by boost alone. There can be a 200 HP difference at 15 psi between 2 different turbos. Why do so many use it as the MAIN factor in determining pretty much everything?

Twin turbo c5

I agree completly I see that alot on here.

vettewreck

iTrader: (1)

I wasn't judging power by boost. However with that said, 15lbs of boost is 15lbs of boost no matter what. Regardless of power, X amount of psi is still X amount of psi. Power can change by the efficiency (or lack of) of a turbo but PSI stays the same.

Blackpanther99

iTrader: (8)

Stock bottom end will hold for a good while with good tuning. E85? pump gas?

Is this LM7 5.3? If it is youll be good.

HexenLord

Oh yeah?

My point is that 15 PSI is not a measurement of power. You're saying the bottom end is good up to maybe 15 lbs.

15 lbs from an ebay GT35 with a stock cam on a 5.3 is about 500 whp at BEST. 15 lbs from a Billet 88mm with a custom cam and good tune could be upwards of 900 whp. So which is it? 15 PSI is 15 PSI regardless and thats all the block can safely handle?

HRHohio

Not to jump in, but there's a big difference here... Stock Cam vs. Custom Cam and Tune.... HexenLord, you're comparing 15 psi apples to 15 psi oranges now.

Take a single engine @ 15 psi (measured at intake manifold), it doesn't matter if you push 15 psi with a GT35 turbo, an 88mm turbo, or an electric leaf blower. If you're measuring 15 psi at the manifold every time, you'll have the same hp. (if nothing else changes... cam/heads/etc).

Most people who ask, "How much PSI can I run" are assuming stock bottom end, stock cam (or maybe a Z06 cam), and stock heads. In this case the 15 psi could correspond to 600-700ish rwhp. I think this is what Vettewreck was meaning... an essentially stock motor.


In the case of the OP, if he's doing a custom cam and ported heads, he could reach the same hp level at 10psi because the restriction (cam/heads) in flow is less. I think that's what you're eluding to (HexenLord).

Regardless, turbo selection should take into account psi and cfm flow.... (referencing a turbo's compressor map).

Hope this helps.

vettewreck

iTrader: (1)

Thank god someone else saw it! ^

Exactly. This is why I said I wasn't measuring power by boost bc power can change. Power can change based on the variant of boost (up or down) but 15lbs is 15lbs no matter whats pushing it.

Clean94Z

iTrader: (5)

Alot of people dont do anything to the shortblock. others suggest regapping the rings,ls2 oil pump and chain,arp rod bolts.... some do all..some do alittle..some do nothing.. ZR1 head gaksets and ebay head studs seem to be most common.

The gen 3 rods have been pushed up to 996whp through a locked auto {there is a video somewhere of the camaro that did it}... its gonna come down too the tune and fuel from what I have seen.

Clean94Z

iTrader: (5)

I read it the same way hexenlord read it.. This statement makes it sound like your reffering boost to hp... stating it "15psi to be safe" comes across like all turbos at 15psi will make the same XXXhp.. You understand what you meant.. Hexenlord was making it understandable for the OP

gpr

iTrader: (6)

This isn't 100% true. If one turbo say the gt35 is making 15psi on a 5.3 engine it is likely not in the most efficient operating range of that turbo compressors map. However if a properly matched turbo is running in its max efficient range making 15psi the temps will be lower and will make more power.

How much more power? hard to say but it will vary, however it probably isn't enough to be nit picky about as there isn't an exact hp number you can say a stock 5.3 will hold in the first place.

Pro Stock John

iTrader: (34)

I'm running an unknown mileage gen 3 SBE LM7. We just checked the ring gaps, opened a few up a little. I reused the stock bearings. I'm running a Baker/Capizzi 230/236 cam, ARP head studs, Melling oil pump, and stock 799 heads. Been 9.2@150 with it so far on E85, we were starting to boost it in in the 20-22 range.

Things to watch, take out timing around peak torque, and make sure you obviously have it tuned safely and smartly.

I will beat the crap out of mine 2-3 more times at the track, I'm hoping to go 8.70s and then swap in a forged LC9 with Summit Racing crank/rods/pistons and a set of TFS 220s.