I have a question, and I hope I don't sound too dumb. How come a guy with an eclipse turbo, can upgrade his fuel system and what not, and put on a big turbo, and set the boost to like 15 or 18, and Ls1's can only do like 6 or 8? what's needed to be done to an ls1 to run on high boost? or are these engines aren't made for that kinda boost? thanks in advance. I am just learning, so no flamming....unless nesecessary lol!

 

airflow.....ask how much air he is pumping with a smaller turbo at 15-20psi vs a t-76 at 8 psi.

 

LS1's come from the factory with fairly weak pistons, head gaskets, connecting rod bolts, and a relatively high 10.1:1 compression ratio. This combination spells disaster when used with high boost. That's why the two major supercharger kits available (Vortech and ATI) are designed to crank out only between 5 to 9PSI of boost.
Cars that come with turbochargers/superchargers from the factory already have motors built to handle boost. That's why you can generally crank up the boost on the cars you mentioned, without adverse effects. The same is true for the 2003/4 Cobra and the WRX Sti.
For us LS1 owners, we have to spend several thousand dollars to prep the motor to handle high boost, if we want the motor to last. Which is why most people just choose to leave the boost low, and save the motor.

Hope that helps.
Happy racing.

 

ttt with this

 

Crunch that was great. I am just wondering now, what is all needed to make an ls1 boost ready like an eclipse or a sti engine. what parts and roughly how much would it cost. Thanks in advance again!

 

I would just do new pistons and rods.

 

Just like cablebandit said its all about airflow......... More air can get into the motor..... more cfm with less boost...........

 

the ls1 weak points are pistons (if boosting) and rod bolts (if turning up the rpms) The stock rods have shown to be quite durable.

 

ok, so let me get this straight, if one changes the pistons (i am guessing, to lower comp. ones), and different rods, and rod bolts. then we can boost 15 psi or what not?? oh i understand that we need to upgrade the fuel system as well. but I am just talking engine wise....thanks a lot.

 

we could go to 15 but not too much higher without head lifting issues. The eclipse 4g63t, motor has 6 or maybe 5 head bolts per cylinder. I dont remember right off hand

on the ls1 the heads pop off with too much pressure

it sucks, I wish I had gone with a stroker and nitrous now. but am too far into this to change at this point in time.

thanks
ed
firebird455@onebox.com

 

Let me ask this, I'm building a 382 all bore iron block (6.0L block) engine with arp studs throughout and arp L19 rod bolts with a factory crank, eagle forged rods and haven't decided on the pistons yet but they will more than likely be coated forged pistons. Using ARP head studs and (which head gaskets cometics??) what kind of boost do you think I can safely run on this combo considering the head studs and the rest of the buildup?

-Sly

 

Just so you no 15psi of boost is just a number and can be different in different cars. Meaning a better flowing or colder air temp and the same "15psi" is more power! Don't go by boost number! As DI-sc with a 9psi pulley is better on a better built motor than stock but with the same pulley!

 

You are really pushing the limit with the stock-type aluminum heads with 20psi on the ls1. Raymer has shown this.

 

Gotcha, I'm pretty new to the *boost* world so I'm trying to learn quickly because I blew the stock bottom end in my car this weekend and am in the process of buying everything to put together my new engine to handle a custom turbo setup. If you guys have the time can you either post here or pm me with what you know about turbo's such as what kind of cam's they like, exhaust etc... my current list of mods besides the new shortblock include....

PP Stage 3 LS6 heads (2.055/1.575)
230/236 .592/.578 114lsa +2 cam
1 3/4 LT's with 3in mandrel bent true duals all the way out the back
Ported LS6 intake, Ported TB and MAF, Ported LS6 oil pump
Hardened pushrods, yella terra rockers, asp pulley
Yank SS4000, 3.73 gears
and all the other little stuff to go along with everything, basically every other supporting mod.

Oh ya what size injectors would be required at these levels and will an in tank 255lph fuel pump be sufficient?

...Dang man sorry for hi-jacking the thread figured this will help you out too since you said your learning too

-Sly

P.S. Thanks for all the help guys!!!

 

along w/ what everyone else said about air flow in and out of the engine, the compression ratio has alot to do w/ it also, and if you were to put a 15psi eclipse engine on a dyno next to a stock LS1, you'd probably get more hp/tq out of the LS1, so when working with boost = % power, you put 8psi on a high compression 350hp engine and your pumping alot more power than over boosting a low power 4cylinder, and I see alot of 4cylinder guys blowing **** up everey week, unlike the ls1 that 90% of the people build them to last, not just for 1 race, but again if you want to talk max psi, I think Rob Raymer got the stock LS1 into the 14psi range, and 14psi on a stock ls1 got in the 800hp/tq range(w/proper tuneing), what does a 15psi stock eclipse engine dyno at the wheels?

 

I don't mean to sound like and *** (but I will, don't make me ), but boost psi is just a number that goes along with CR. PTV cearance and all the others. The idea for power is CFM airflow through the engine. The more through the engine, the more power potential.

Cylinder pressure makes power, period! If you have high CR, boost only can raise cylinder pressure so high without grenade results. Each engine is designed for a max cylinder pressure. This involves piston strength, head clamping force, bottom end strength and a lot of other things. Boost motors reduce CR to accommodate extra pressure in the cylinders. A little boost with high CR makes the same hp as a lot of boost with low CR for instance. The ability of the engine to ingest and expel gasses also makes a big difference in the amount of boost psi an engine can live with. A better exhaust with the same setup will REDUCE boost psi, but keep the same or get better hp numbers. Don't ask how much boost, ask how much CFM the combo can process! Just like N/A, think about head flow, exhaust flow and rpm range of the powerband. That'll give you the real answer. HTH

 

well Assassin, before I say anything I want everyone to know that I am a BIG LS1 fan.

now, about HP of an eclipse. if you were to take let's say a 98 eclipse GSX. and put the normal boltons, upgrade the fuel system, slap on a turbo like a t3/t4 60-1, or even a tad smaller, like a 50 trim. you get some serious numbers, i mean 400 HP is on the low side for that turbo setup.

Part of the reason why they get these numbers is because these ******* push 18 - 25 PSI, with ease. I guess thats how these motors are built to work or something, I don't know. but if these guys were forced to push only like 8 psi or something like that, then ur right, their engine next to a stock ls1 is week.

I hope i didn't rub off as a dsmer....I don't want to get flammed!

 

oh by the way, a lot of the dsm guys build their engine so they can push 25+ psi, which is also another crazy thing.

 

but Mike Brown and wheel to wheel have shown us that we CAN go past this.
not sure how much boost he's pushing, but he's at 1150 crank HP with his 382 all aluminum ls1 (true ls1) with standard arp head studs and grafite gaskets.

 

I could be wrong but I remember reading that 1lb of boost is worth more than 1point in compression so that would suggest that if you can lower your compression and run more boost you will make more power than a higher compression engine with less boost. I know there's some kind of formula out there but I'm not going to begin to try to figure it out.

-Sly