4.8 intake

[Daddydaughter2012]

Hello I have a 4.8 vortec in an 01 Silverado looking to produce 400 to 500 hp wat kinda intake should I use

[SMWS6TA]

A LS6 intake will help you get there. If looking for aftermarket a FAST 92 intake would be the biggest one I would recommend.

With the LS6 - you can pick up used for about $300-$450 used on ebay or in the for sale sections of car forums.
The FAST 92 Intake - this is little harder, finding them used is difficult and for new they run about $950. You do not need a 102mm intake for that tiny 4.8.


Also you may benefit from a LS2 intake as well.

[Daddydaughter2012]

Should I upgrade the water pump or anything else I have short tube headers

[SMWS6TA]

Long tubes are always best. But depends on where you live if legal and is smog laws prevent

[Daddydaughter2012]

No smog laws here what's the difference between longs and shorties

- - - Updated - - -

Other than the size

[SMWS6TA]

Shorties are just barely a step up form stock headers. Turbo builds mostly used them. Long tubes are design to give equal runs of the tubing from the flange to the collector. This helps in savaging the gasses and reducing back pressure faster helping the engine produce more hp/tq over stock headers.

LTH will at best move the CATs further back into the Y pipe or if you are like most of us we get rid of the CATS and don't care.

There are some Y pipes that the CATS are part of and also some exhaust kits that are CAT back systems to make them compliant to smog laws.

[Daddydaughter2012]

Would it be the same as lth if I build a straight y pipe?

[SMWS6TA]

LTH = Long tube headers

If you get LTH's you'll need a new Y-pipe. They are 2 kinds. Y-pipe with CATs and ORY (off road Y-pipe). The majority of ppl get the ORY.

There is a 3rd option - true dual pipes. Basically a straight pipe out to the muffler. Some put in a x pipe cross over, some don't.

[Daddydaughter2012]

Okay wat about the water pump

[SMWS6TA]

is there some thing wrong with it?

If no keep it.

[Daddydaughter2012]

No nothing wrong with it I wanna get 450 to 500 hp can I get that with bolt ons a cam and a custom tune?

[SMWS6TA]

no sure what the 4.8's are capable of.

With the right heads & cam pkg with a LS6 or FAST92 intake you could be in mid 400's. My 403ci is putting down 450hp with a break in tune. Still got more in it. Having to fix some issues that popped up on dyno. I also broke the tranny and waiting on it getting fix. Click on my engine build in my signature to give you an idea on what to expect.

[Daddydaughter2012]

It's has ls1 heads on it they are stock should I upgrade

[SMWS6TA]

What's the heads number?

243, 799, 317's

[Daddydaughter2012]

706 heads

[SMWS6TA]

Too many variables to guess. If you have some port work on the 706's you'll pick up some flow and a bump in HP.
243's depends on your piston set up, you may loose some compression because the stock 243 is 66cc and yours are I believe 59cc. You can have the 243's milled down and ported to get the compression back up and have flow. But then now you're in the what's better spending $$ on, porting heads or going with aftermarket.

This is something you would be best to talk with those two I mention in your other thread. They both can design a custom cam for your needs.


This is an example of what I mean about too many variables:
My engine build, I have 4.005" flat top pistons with a -3cc relief cut, 6.125" rods and a 4" stroker crank giving me a 403ci. With the 243 heads my CR is about 11.1 to 11.5. Now if I had dish pistons I would be in the mid 10's for CR and if it was a stock stroke I would be in the mid 9's for CR.

[Daddydaughter2012]

Okay so I can keep the 706 heads and just port and polish them to produce more hp...bout how much hp would that produce? Roughly

[SMWS6TA]

10-20...

[Daddydaughter2012]

Okay thank you

[Daddydaughter2012]

One more question on the swap to the ls6 intake do I need to convert anything like egr or fuel lines? It has a mechanical fan not electronic should I swap them out?