SwampWS6

iTrader: (7)

I know the gurus here are going to lay it on me, 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?

96lt1m6

iTrader: (31)

Im a little confusd, your sig shows 11:1 383 that would definitely be high compression. I sure would not turbicharge a street motor with t h at type of compression. ...........that cam is NOT a boost friendly grind at all....
Do you have a different built Lt1 that you have not given specs on????????

Catmaigne

iTrader: (6)

That cam looks more suited to a blower because of the split. However, I've seen a few turbo builds online with comp blower grinds that have done just fine with turbos.

Are your pistons forged? What alloy? How thick is the crown? Will you be running water/meth? Intercooler? What gas? Need more details.

SwampWS6

iTrader: (7)

I would run it with no more than 5lbs of boost because of CR. All forged internals with dished pistons. I want to run 93 octane and occasionally some race fuel for track days. The motor is out of the car right now so I can put a much thicker gasket on to knock down the CR. I know the cam is not a turbo cam but I thought it wasnt to overly aggressive for a turbo setup.

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!

96capricemgr

iTrader: (1)

The compression is low for NA and high for boost. IMO with careful tuning though you could make it work on modest boost like the 5psi you are talking maybe a little more, I would just look at water/methanol to cool it and add some octane.

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.

Puck

iTrader: (17)

While a bit high, a forged 10.8:1 383 can run well over 5#s. It is stronger then stock and stock motors run 7#s with only a few tenths less CR.

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.

SwampWS6

iTrader: (7)

Thanks caprice, the only thing I was really worried about was the cam. I might go out and find the thickest headgasket I can find to maye get CR around 10:5 or lower. I will have to get the ECU retuned

96capricemgr

iTrader: (1)

In response to Puck pointing out stock engines sometimes run over 5psi most guys who do that on stock LT1s do so with unported heads hindering filling of the cylinders.

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.

Catmaigne

iTrader: (6)

If you're gonna take the heads off then you might as well get the chambers opened up if you can. I've never heard of stock TF 215 heads, are you talking about the AI ported set? The TF 195 castings can be opened up to 67cc according to TEA and Lloyd (from 62cc). Lloyd told me he could get each to 66-67 assuming the heads don't need to be shaved, he was only asking $100 + shipping just for chamber work. TEA wouldn't give me a price.

Catmaigne

iTrader: (6)

I think a single 70mm turbo sounds a little small for 383 IMO, but if this isn't a max effort build then I guess it doesn't matter.

SwampWS6

iTrader: (7)

No its not a max effort build because I did not intend for it to be a FI build from the beginning. So I thought a 70mm would be a moderate build to this app. The heads came from Lloyd so at least comfortable with That. My concern is the cam at this point. And I've been contemplating meth injection because of a little research I've done. Can someone elaborate on the role of meth in my setup????

Catmaigne

iTrader: (6)

A 383 with your ported TF heads and big cam will be choked by that 70mm, if anything I think you should downsize on the cam and get something without a big split in duration and less overlap. I don't know what your LSA is but I'm guessing if Lloyd spec'd it for NA then it's probably pretty low. In the end, the turbo will still hold you back but if you make it fun to drive you won't feel bad about leaving that power on the table.

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.

Catmaigne

iTrader: (6)

Is your car A4 or M6?

SwampWS6

iTrader: (7)

Its a M6...... I know the cam is the weak point, so im trying to figure out what Im gonna do about that. It has a 110 LSA and I know optimal is 112-114 LSA for a turbo application. And I know that power will be left on the table considering the stated circumstances. I wanted to always to do a turbo build since I was little. But due to the price of turbo kits for LT1's and LS models I decided to wait. Then I ran across this deal, I was like f*** it, Ill make it work!!!!

96capricemgr

iTrader: (1)

Sure you could max out a 70mm turbo with a 383 but in doing so you are going to make a fair bit more power than you have now.

The compression and such should make it snappy.

SwampWS6

iTrader: (7)

Question Caprice, I see that there are .080 head gaskets out there and if I use it, it will lower my CR to about 9:89. I think this will make the app better for the turbo. The only problem I see now is Quench...... and the gaskets are Copper........ What are your thoughts? Im currently working on getting a cam with a tighter LSA......

bowtienut

iTrader: (1)

I'd avoid pure copper gaskets on a street engine. They'll seep coolant.

SwampWS6

iTrader: (7)

Thats kinda what I was waiting to hear

quik95lt1

iTrader: (7)

what he said, run like a .055 cometic on it call them they can make you whatever you want, if you can get the CR down to the low 10's you should be able to jam 10lbs or so into it on a good tune with pump fuel, with that cam in it you may even get more out of it........as for the cam don't freak I tuned my friends ls with a d1 on it with a cam just like that on a 112LSA....it made fantastic power on 12lbs

SwampWS6

iTrader: (7)

Thanks a lot....... I am just a little leary of going to a .055 Head gasket. After doing some recalcs I came up with 10:72 CR. I would love to go .055 gasket but now im worried about killing my quench. I am changing the cam to a 223/223 with a 114 LSA and running E85 to have the potential to run more boost. I am actually posting my 110 LSA for sale.......LOL!