Just another twin turbo 4.8L build. Project "Short stroke"

[TheBlueBomber]

Around April of last year I bought my 1979 K10 for $1000 and limped it 2 hours home. It had no brakes what so ever and was leaking oil like crazy. Any who I brought it home cleaned it up and drove it around for a few months after working a few kinks out of it.




The truck from the factory had a 350/th350/np203 setup but at some point an '80-82 305 was swapped in. And boy was she tired.


Once those kinks were worked out I went four wheeling a few times... the last time I got cocky since I knew my reverse was going out... it went out lol.







Que in the twin turbo LS build. I was thinking about rebuilding the trans and then building a 350 for the truck but after about a month of pressure from friends I decided to go LS. But I wanted to take it farther then that.

So I got a 5.3/4l60e/NP241 setup going in right now that I'm almost done with. Wiring is being done by a good friend of mine and I just need to set up the 4l60e linkage, fuel system, and exhaust... Cake.




While I'm driving the K10 I'll be building the 4.8l for the setup. I have a build thread for the truck but I wanted to make a secondary thread in here on my setup so I can ask questions about what I'll end up doing. Haven't thought much on the transmission I will use but I definitely want a manual.

So walking around the junkyard looking for a good motor to use and I found just that. It's a 1999 4.8L engine. The engine spun freely and I pulled the passenger side head off and saw that it had flat top pistons. I knew it was what I was looking for. Pulled the motor and grabbed a few things that I need for the 5.3L and I was on my way home. The engine will sit for the most part until I get the truck running and driving and then I will turn all of my focus on that.





I don't plan on four wheeling much anymore unless its light trails/the beach. I put my first dent in the bedside and I decided I had enough lol. Build thread for the truck is here. http://67-72chevytrucks.com/vboard/s...d.php?t=605433

[TheBlueBomber]

Couldn't help myself today... i just had to dive in. Pressure washed as much grease off as I could.

Here is before I started cleaning


Nasty




Nasty nasty




Pulled all that crap off and started prepping for the wash... idk why I even put rags in the head...



Finally got her clean...er

[TheBlueBomber]

Some more pics


Deliciousness in the oil pan







My beautiful helper


And this is how it'll sit until I can get back at it next weekend.

[hotrod 80]

Wow , that motor was abused .

[TheBlueBomber]

Originally Posted by hotrod 80

Wow , that motor was abused .

Yes it was. I grabbed this one because I was planning on tearing down the motor anyway. Might as well grab the motor No one would plan to use. The outside of the truck was pretty clean. Anything drive train wise was Discusting

[tinydb84]

Are you going to rebuild it? Or just hone it and pray? hahaha

[TheBlueBomber]

Originally Posted by tinydb84

Are you going to rebuild it? Or just hone it and pray? hahaha

Haha definitely going to build this one. I really want a reliable build. Pulling a motor every year will get annoying to me. I've got a lot of planning and research to do for this motor still. Main focus is getting the truck running with the 5.3 for now.

Definitely looking at getting 2 70 mm turbos. Haven't decided on the cooling system yet whether I want to run one or go e85 and methanol injection... I'd like to be able to get fuel for the truck locally so I need to find out what's available in my area. No need building the engine if I can't fuel it.

Once I figure out what fuel I want to run the rest of the system will come together.

The main answer to most questions geared towards this build will end with "because race truck"

[tinydb84]

Very cool. I wish we had E85 around here, hell we dont even have 93. I think twin 70's is going to be way to big though. Probably something closer to twin 35's. I plan on doing a turbo on my 5.3, eventually....

[TheBlueBomber]

Originally Posted by tinydb84

Very cool. I wish we had E85 around here, hell we dont even have 93. I think twin 70's is going to be way to big though. Probably something closer to twin 35's. I plan on doing a turbo on my 5.3, eventually....

This dude called sinister has twin 70s and It seems to be a good setup. He started with 63's and said there wasn't much lag and there was a little bit of lag with the 70s but it came with a big performance increase. He runs no intercooler e85 and a water meth spray in the intake.

Video of his car.

Sinister 5.3 Twin 70's - YouTube

His name on ls1 - tech Is wicked69. This is his thread. http://ls1tech.com/forums/forced-ind...tml?styleid=26


Oh and It's a daily driver

[tinydb84]

I have seen him on the Tech. For some reason I thought he was running smaller turbos. I stand corrected

[BR3W CITY]

I clicked for turbo's and all I see is engine sludge

[TheBlueBomber]

Originally Posted by BR3W CITY

I clicked for turbo's and all I see is engine sludge

Hahaha!! They'll be on the way here soon I promise.

[hotrod 80]

I am also interested in this build . I have a S-10 with a 5.3 and would like to do a single 70-76mm intercooled pump gas build .

[swb85]

I think you'll want to rethink your turbo choice unless you're shooting for silly power, especially in a big ol truck. I'm knee deep in a twin turbo build on my 4th gen camaro and I'm using twin turbonetics 6165's on a 370ci motor. I'll have enough compressor wheel to make over 1200hp without taxing them hard. Twin 70s is nutso unless you want 1500+hp IMO. Looks like a cool build!!

[TheBlueBomber]

Originally Posted by hotrod 80

I am also interested in this build . I have a S-10 with a 5.3 and would like to do a single 70-76mm intercooled pump gas build .

I feel like that will be the way to go. I'm sure the 5.3 alone is fun but after seeing the luv I'm guessing it'll be no comparison

Originally Posted by swb85

I think you'll want to rethink your turbo choice unless you're shooting for silly power, especially in a big ol truck. I'm knee deep in a twin turbo build on my 4th gen camaro and I'm using twin turbonetics 6165's on a 370ci motor. I'll have enough compressor wheel to make over 1200hp without taxing them hard. Twin 70s is nutso unless you want 1500+hp IMO. Looks like a cool build!!

You're definitely right. We will see which way the build goes as I start getting into it deeper. The bottom end is definitely going to see major upgrades, I want this motor to be able to hold stupid power which I know it can stock. This truck is my "rat rod" I want it to have a stupid amount of power for no reason but pure enjoyment. Plus I'd like to surprise some c6 vettes at the track.

[tinydb84]

Originally Posted by TheBlueBomber

You're definitely right. We will see which way the build goes as I start getting into it deeper. The bottom end is definitely going to see major upgrades, I want this motor to be able to hold stupid power which I know it can stock. This truck is my "rat rod" I want it to have a stupid amount of power for no reason but pure enjoyment. Plus I'd like to surprise some c6 vettes at the track.

Is there a reason you are building up a 4.8/5.3 lower end? I would think in terms of cost vs hp it would be better to start with a 6.0 if you are sinking money into it.

[TheBlueBomber]

Originally Posted by tinydb84

Is there a reason you are building up a 4.8/5.3 lower end? I would think in terms of cost vs hp it would be better to start with a 6.0 if you are sinking money into it.

I thought so too but Imo it's all the same just with a different name. Guys pump serious hp out of these 4.8/5.3 blocks and since it's so much easier to get one of these vs a 6.0 I just grabbed it.

Don't get me wrong, if it was a 6.oh sitting in that truck I would've grabbed that pretty darn quick haha

[BR3W CITY]

For a turbo build, I'm an animal of opportunity at this point. If you got a 6.0, then use it...otherwise, run what you can find. In my case, I've already got 6.0 parts around, and a few sets of heads...so going to the smaller bore wouldn't make sense, as I lose use of those good parts.

If your pulling something out of a yard, who cares? Most of the time, on the first incarnation of any big hp build, you just "build it" by running it till it blows, then upgrading whatever broke. Heck thats how you used to do it before guys had money for complete "stages" of upgrades etc.

[Super73]

I suggest rethinking the size of the turbos as well. I spoke to several turbo companies before I settled on twin Precision 67/68's for my 418" LS motor. My motor is 131 cubic inches bigger than yours and these turbos on my motor should make 1200rwhp all day long and carry RPM to roughly 7,000.

Here is a 427" LS with Precisions 67/66 making 1143rwhp on 19lbs boost.
http://ls1tech.com/forums/dynamomete...1040-rwtq.html

The point I am trying to make is selecting a turbo based on CFM required for your power goals and selecting the smallest one to achieve that will most likely make you much happier when it comes to spool time in a truck.

Spool is sort of like converters or cams, each person has their own interpretation of how much "lag" is acceptable.

[tinydb84]

Super73-Question for you (since you probably know).

Looking at Sinister's build he has the twin 70's. Does the fact that he is running E85 make up a significant difference for lag time? I know that you have to run a larger amount of fuel but does that necessarily produce a larger gas volume?

One good thing about using turbos too large for your 4.8 is that when you blow it up (if you do) then you wont have to buy new ones for a 6.0 or 408.

[Super73]

I don't believe the fuel volume will help in spool time.


If twin 67/68's move enough air to make 1200rwhp on a 418" motor, they well surely move enough air to do the same on a 4.8.

I have seen twin 66's make 1100rwhp. Again it comes down to ones goals.

[TheBlueBomber]

Originally Posted by Super73

I suggest rethinking the size of the turbos as well. I spoke to several turbo companies before I settled on twin Precision 67/68's for my 418" LS motor. My motor is 131 cubic inches bigger than yours and these turbos on my motor should make 1200rwhp all day long and carry RPM to roughly 7,000.

Here is a 427" LS with Precisions 67/66 making 1143rwhp on 19lbs boost.
http://ls1tech.com/forums/dynamomete...1040-rwtq.html

The point I am trying to make is selecting a turbo based on CFM required for your power goals and selecting the smallest one to achieve that will most likely make you much happier when it comes to spool time in a truck.

Spool is sort of like converters or cams, each person has their own interpretation of how much "lag" is acceptable.

I definitely agree with everyone 70s is a bit over kill especially for a street truck and I'm definitely open to and exploring other options like the precision turbos

And one thing I want to make sure of is to avoid being over cammed/turbo'd

Originally Posted by tinydb84

Super73-Question for you (since you probably know).

Looking at Sinister's build he has the twin 70's. Does the fact that he is running E85 make up a significant difference for lag time? I know that you have to run a larger amount of fuel but does that necessarily produce a larger gas volume?

One good thing about using turbos too large for your 4.8 is that when you blow it up (if you do) then you wont have to buy new ones for a 6.0 or 408.

A big part of his reasoning for the e85 fuel is to help keep his IAT's down so he didn't have to run an intercooler. He mentions the fact there is significant lag but when he hits boost it pulls like a train. The difference in his experience is night and day between the smaller On3 turbos and the 70's

Originally Posted by Super73

I don't believe the fuel volume will help in spool time.


If twin 67/68's move enough air to make 1200rwhp on a 418" motor, they well surely move enough air to do the same on a 4.8.

I have seen twin 66's make 1100rwhp. Again it comes down to ones goals.

Without a doubt. Speaking of goals, I never mentioned in a previous post what my goals were... originally when I thought about doing this I was thinking around 650hp... but since the truck will be running soon and I'll be building this engine outside of the truck I don't see why I can't aim for an 800+ hp build.

[BR3W CITY]

Originally Posted by TheBlueBomber

A big part of his reasoning for the e85 fuel is to help keep his IAT's down so he didn't have to run an intercooler. He mentions the fact there is significant lag but when he hits boost it pulls like a train.

Less tubing = less lag. Also since the ethanol burns cooler at the same cylinder pressure, you can load the system more without generating as much heat and risking detonation. Minimal tubing (and if you wanted, running straight methanol in addition), and you can run a lot of boost at a reasonable compression without popping anything.

I know Wasted Income runs pump gas, but uses methanol injection instead of an intercooler on his blazer. Not sure how his lag is tho.

[y5mgisi]

Smaller turbos for sure. The truck will be alot funner to drive with 700hp than it would with 1200hp.

What exactly are your intentions with this truck? DD? Are you doing to drag race it a bunch? etc. That will determine alot about what direction you want to go in. But you can get these motors to idle nice with the AC on and make the 700hp and make it just a sweet running DD sleeper.

[TheBlueBomber]

Originally Posted by y5mgisi

Smaller turbos for sure. The truck will be alot funner to drive with 700hp than it would with 1200hp.

What exactly are your intentions with this truck? DD? Are you doing to drag race it a bunch? etc. That will determine alot about what direction you want to go in. But you can get these motors to idle nice with the AC on and make the 700hp and make it just a sweet running DD sleeper.

Definitely wanting it to be DD/sleeper status. I'm really leaning to the E85 fuel just because there is a gas station 4.5 miles from me that sells it.