RiDgeViStaRider

iTrader: (7)

Just woundeing why, the 5.3L with 317 heads make a T76 feel like a slug off the line but pickup top end?

anheuserbusch08

iTrader: (11)

ur lowering the compression way beyond what ull actually need. ive seen 5.3s with ls1 head making fantastic results

Cam72aro

iTrader: (28)

^^^^ What he said. It lowers compression.

Burken01

iTrader: (88)

What compression? If it's super low then turn up the boost. Low boost and low compression makes a car sluggish... 9.5:1 cr will give decent drivability while not in full boost..

got-a-ls1

iTrader: (12)

yea dude 317's on a 5.3 is extremely low compression.

runninfromthelaw

iTrader: (22)

317's are 71cc chamber so it drops a 5.3 down to 8.5:1cr. Stock 5.3 862/706 are 61cc and 9.5:1cr

Sarg

iTrader: (6)

depends on the 5.3 also. The L33 uses flat top pistons instead of dish.

pwrtrip75

iTrader: (8)

What engine with 8.6:1 compression isnt a slug? People are under the impression that turbos need low compression. Probably true if you are trying to run 30psi on pump gas.. But if you had a turbo to achieve that and you are running a stock 5.3 odds are it would fly apart well before that...lol. So no need to lower the compression to prepare an engine for something it will never see. I did this also....it sucked. lol.

milkplus

iTrader: (3)

An 8.5 5.3 without a turbo is like a 150-200 hp combo... so there's your sluggish right there.

Do you have data that says a lower static 5.3 with more pressure is more efficient then a 10:1 5.3 with a t76? What makes you think it will "pick up top end"?

Grr

iTrader: (2)

not only that, but it is also usually paired with a cam like a ls6 or 224r, where your dynamic compression is down in the low 6s or high 5s. THAT is the real problem

Ferocity02

iTrader: (60)

It makes is a slug when NOT in boost, which for a street car is 98% of the time unless you're Vin Diesel

tta656

iTrader: (5)

GN's are v6 with 8.5 CR and are not sluggish when not in boost(well not that much) and only rated at 245hp in boost

Convertor stall
Rear end Ratio
Ar. of exhaust housing..

speedtigger

iTrader: (16)

As previous owner of 2 turbo Regals, I beg to differ. They feel real sluggish when not under boost. Fortunately they spin up pretty quick.

Burken01

iTrader: (88)

can you elaborate on this a little more?

I'm going with a ls6 cam w/317 heads, ls9 head gasket on a 347 with -2cc valve relief flat tops..

I would like 9.5 compression

Grr

iTrader: (2)

that equals out to 9.45 compression and 7.08 dynamic compression.

cjvmboricua08

ok so let me see if i get this right... i got a 5.3l with 317 heads, ls6 cam, and flat pistons.. which should be 9.5:1 comp right?? should i swap into ls1 heads for better results or turning the boost up at lower rpms should even it out??

Grr

iTrader: (2)

Actually I used the Ls1 bore for that. Your combo is
9.05 cr
6.75 dynamic cr

That is why they are such dogs. That is a 200whp at best N/A. I would run 241s myself over 317s which is
9.55 cr
7.15dcr

o2camaross

iTrader: (2)

Grr, can you explain the dynamic CR and how you calculate the DCR and STR? Thanks

Also, I understand the significance of STR, but what is an ideal DCR for a street vehicle and how does that play into driving or response. Im sure Im not the only one who would find this info useful

cjvmboricua08

i see. understand why prior of the turbo build it only dynoed 329/321. what kind of boost could them 241s hold?

o2camaross

iTrader: (2)

ok I looked it up and understand now. Now I just need to figure out when my intake valve closes lol. Would that be on the cam card?