4.8 ls6 top end hp
 

Hey guys. I decided to slap a FI 4.8/4l60e I got laying around into my iroc until I start my iron ls1 build for it. What hp do you think I would get from a stock 4.8 with long tubes, ls6 intake and heads bolt ons? I already have the ls6 intake and heads.

Putting any kind of cam in it?

I did not plan on it.

279rwhp

What fwhp is that around

https://cimg7.ibsrv.net/gimg/ls1tech...9559afa42f.jpg
I actually have a 4.8 and 5.3, but the 5.3 is the one I will bore out to ls1 specs, build and reuse the crank. I already have the harness made up and ecm reflashed for the 4.8

About 320FWHP. The cam in the 4.8 is the same as in the 5.3, which is 191/190, .457/.466, 114LSA in case you didn't know. The smallest LS cam GM made.

I gotcha. Yea I knew they were about the same. I was going to leave it alone because I never installed a cam before and I would have to get the ecm reflashed or dyno tuned for the new cam. I figured I could get away without a tune for the ls6 intake and heads.. Could I get by without tuning for the ls6 intake and heads?

Also not to mention possibly having to change valvesprings, due to the 243 heads came off a ls4

As long as your using the injectors that the ECM is tuned for I don’t think you will have any problem with a fairly stock tune using 243 heads and a ls6 intake. Why would you need to change valvesprings if your going to run the stock wimpy camshaft?
If it were me I would at least look for a stock ls6 cam, you should still be able to run that without tuning issues. And gain what 20 or 30hp? For like $150

Depending on a cam swap I would maybe have to change the valve springs. I dont know the max lift for the ls4 243 valvesprings. Ls6 cam sounds fair for the hp trade off but I never changed a cam before though.

The ls6 intake that I have is complete with stock fuel rails & injectors

You can buy a 5.3 crank and rods for the 4.8 and it will be the same as the other engine. Either one can be opened up to 5.7 specs. EBay crank and used rods around 125 bucks...

Why do you want to put the ls6 heads on it? It's going to have more compression and therefore more power with the smaller chamber (61cc vs. 64cc) 706# or 862# castings. Also the 2" intake valve is completely unnecessary for the tiny 4.8, it just doesn't demand as much air as the larger stuff. if you want to make some decent power with a 4.8 mill the stock heads to get the compression above 10:1 and choose a cam that closes the intake valve reasonably early

Cam swap is super easy, and even easier with the heads off.
You will need a new cam retainer plate because the gaskets never reseal and there molded in, some reason no one ever mentions this, most parts store will have them under $20
The hardest part is getting the crank balancer off, without the proper tool its almost impossible.
plenty of videos on this on youtube

this is the tool I use now (because i do them alot) its exspensive but the ballancers come off like butter with it ggt-180
https://www.ebay.com/p/Ggt-180-Harmo...d=192882918739

you can rent some other ballancer tools from most parts stores that will work if you only plan on doing this once I wouldnt spend the money on the tool above.

And this is what I use to install, just be sure to put some kinda lube on the threads everytime you install.

Also as stated earlier, you really wont pick up much from the head swap, If the 4.8 still has the stock heads on it i would just leave them alone. throw in a $80 set of ls6 springs, a cheap cam and have fun.
You could even bump it up to a ls9 cam still around $150 https://www.summitracing.com/parts/nal-12638427
Who tuned the ECM? and do you know what size injectors it is tuned for? im pretty sure ls6 injectors will be different than 4.8 stock injectors.

If you can put a engine into a car you can change a camshaft lol.

Valve springs can be a pain but with the engine out should be easy, do seals too. With that done to the engine you should be able to sell it for a better price once the iron block engine goes in.

Brandon with lt1swap tuned the ecm. The engine has 706 heads which the owner said the engine would loose small amounts of coolant but not on the ground so I figured it was the heads.No steam blowing out,Oil was not milky and nothing in oil pan. I drove it and everything.

I would imagine one could swap out a cam if he could pull and install an engine but I am a helper at best.

Good time to learn!, you might have to use the 4.8 injectors on the ls6 intake

Yea, I'll think about it. I was told if I install the ls6 factory cam I could get by without tune.. The heads have to come off anyway, I can either use the ls4 243 heads or another set of the 706 heads from the 5.3..

The 706 heads on the 4.8 are cracked I believe . I'm just trying not to spend much money and need a dyno tune for this thing

If it's a swap it's going to need a tune... I don't know why people still try to do this wrong. I wouldn't even bother going through with it if you aren't going to tune it. What a waste of time and money. 4.8 + ls6 cam + stock rev limiter and tuning + stock converter is going to suck big time and it's going to be slow and you are going to be really disappointed