How many lbs of boost?
, so here it goes: I ran across a unbelievable deal on craigslist a new garrett 70mm turbo with all the new plumbling, intercooler etc. My question is what things should i check for? (Like play in the shaft and making sure everything fits ) And how many lbs of boost should I run? When I asked about CR, last year many of you said that my CR was too low and just keep it that way til im ready to boost. Well, I think the time has come. This is my first turbo setup and I have a decent understanding of turbos and how they work. There are just some technical things that I do not know that maybe yall can help me out with. What do you think? Do you have a different built Lt1 that you have not given specs on????????
Are your pistons forged? What alloy? How thick is the crown? Will you be running water/meth? Intercooler? What gas? Need more details.
I got scrutinized earlier in the year because about 85% of the posts said my CR was way to low and at least 70% of those guys just said boost it because it was so low. At the time I wasnt really planning on it, but the deal im getting on an entirely new setup is once in a lifetime chance. Since im at the point of picking up minor parts to finish the initial build, this deal came along.
I understand this build is not ideal, and did not start as a FI build but I thought it would be safe enough with everything being forged, and having moderate CR and running no more than 5 or 6 psi, I thought it would be ok...........
Keep the info coming!
I would presume the cam is a fairly tight LSA with a decent amount of overlap? I would probably change that. "Custom" NA cams often use overlap to let the vacuum behind the exhaust pulse to pull fresh air in, with a turbo you are going to be looking at backpressure that wont allow that to happen as designed.
Like stated though, you need to check the cam. Duration at. 050 is useless on its own, but with the rest of the specs and it's overlap you will have a better idea of how it will like boost. An NA cam can spit the boost right out the exhaust valve due to the high overlap.
Take this thread to the boost section or PM someone who actually runs a turbo on an LT1.
Trending Topics
I would probably shoot for 7-8, but being a first foray into boost I would probably start at 5 and work up.
I will say I have never played with boost, but I have researched it to wake up the 5.3l in my truck. 300hp in a 5300lb truck is rather anemic compared to the car.
The Best V8 Stories One Small Block at Time
Meth/water injection is to help cool the intake charge and cylinders so you don't detonate. Meth will actually boost your octane rating but nothing substantial. If you have forged Mahle's then they're probably Power Paks with 4032 alloy (unless they're Power Pak Plus which is 2618, which is unlikely). They're not going to take as much abuse because of the material so running an injection system is an absolute must at your CR or else your gonna end up breaking chunks off of the top land or blowing holes in the crowns.
The Mahle's that are going into my 355 are actually intended for a 383 with a stock length rod. The top land is .326" and the crown is .197" under the dish, 4032 alloy. I plan on running up to 12psi intercooled on 93 pump gas, it will use water/meth with higher boost. However, my CR will be around 9.2-9.3:1 and I'm trying to be on the safe side. Your setup will be on the edge if you're not careful.






