Kyon

LS motors (i have heard) can handle around 10psi on stock internals. is that because of weak internals, or is because of detination on stock compression. if it is because of internals is it the rods or the pistons.

what internal parts limit the rev to around 7k? i have some gsr bearings, but is the head capable? should i go with dual springs

just me being curious

dallasb84

ls can handle close to 15 but reliable its closer to 8 psi....

as far as i know and from my own experience. its the compression and more along the lines of blowing head gaskets, burning rings, throwing rods, burning valves, and bearings.... all the things that should be upgraded when boosting.

im pretty sure a stock ls rotating assembly when balanced could handle 9k or more....

the head is what limits the ls in my opinion..

what do you expect a factory ls motor to compare to:

4door_GSR

you can put it on 14-16 lbs saftly its all about the tune and how well the maps are laid out. i have plenty of friends that have ls turbos that are running any where from 10 -16 lbs daily . the limit on ls reving past 7k or 7,500 is the rods ther not as strong as gsr or type r's and they have a diffrnet stroke but ppl put arp rod bolts in them and i know ppl with all motor setups and turbo set ups reving to 8500 with no problem the only thing is that stock ls heads usually max out between 7500 and 8000 with out any mods... but as far as head gaskets and valves and compression and all that sutff you dont have a problem its all about the tune for further information call my friend mat shue he is a big tunner in the richmond area and has tunned many engine setups and can tell you much more ( im a mechanic and i put togeather alot of setups and im just tryn to put you in the right direction)

mat shue
www.shuetunning.com
804-502-1920

jlgrtype

want to boost more? replace your internals. pistons, conecting rods, cams retainers and springs, head gasket. want more rpm? balance your crank.

Verbal

Then your sleeves would go. Althought there are a bunch of people making 3-400whp on stock blocks.

As far as RPM limits, The bottom end, nor the head are designed to rev high. The bottom end doesn't have the girdle (compared to the GSR bottom). The head, well, i am not to familiar with an LS head, but i know they don't like to rev high in stock form.

I have run an LS bottom to 8500, on ls/vtec setups...with no ill effects. I don't recommend it though.


*4dr_gsr also hit on some points. Like he said, i have seen many an LS running around on 15psi, a thicker headgasket and chrome/neptune.

MaxPower

When did boost become a way of measuring HP? Iv been seeing this a lot.

BAD4DR

When uninformed idiots began taking over the scene!
I used to get asked all the time "How much boost you runnin?" when I drove my SRT-4. The 18 lb spike I was running on a TD-04 is in no way comparable to 18 psi on a 50 trim T3/T4, but.....That was always the first question.....

Interestingly, at 10 psi, almost any T3/T04E on the same size exhaust produce about the same horsepower..... It's the differences when you're actually within the efficiency range, that seperate them.....

I find it interesting, they keep talking about the tune. Face it, a T3/T4 @ 10 psi, is about 40-50 % efficient with the airflow of a 1.8L. The air is rather hot, with little benefit in airflow. At about 14 psi, it's actually closer to 70-75% efficient.... That being said, I think I'd be doing some fueling mods, making sure it had plenty, run a little conservative on the timing if I had to, and run the additional 4 lbs of boost. Each pound of boost is worth enough at that level to get more than a degree or two of timing!