4.8ls 300-350whp fb rx7 for raod course use
08-12-2019, 11:49 AM
#1
4.8ls 300-350whp fb rx7 for raod course use I have a 4.8 that i was going to swap into my 85 c10 but recently found a 6.0 for very cheap ($500) that will be a better fit for my truck; so the 4.8 will be the power plant i will use for the race car. The car will be a 1985 fb rx7 (2400lbs) a car that my dad has just sitting around going bad. The rx7 is a gls-se which is the one that most want because it came factory with power steering, 5 speed, 390 limited slip rear, disk brakes all 4 corners.
So that's is the back drop, now i need your guys help with my 4.8 hop up. I would like for the 4.8 to stay N/A so nothing thats crazy..im thinking 300whp in a less than 2400lbs car would be pretty quick on a road course; plus should be fairly reliable at that power level. Right now i have a complete 2003 4.8 and a Corvette z06 ls6 intake. I know i need a cam, long tube headers maybe a dry sump system and i plan to use the factory rx7 oil cooler. The engine would need to rev out to at least 7k rpm. Which cam do i need? Springs? This will be a manual so i wont have to deal with stalls and all that jazz. Lol. do i need to mill the heads to gain some hp? Trying to stay under 5k for the whole build. Of course as i get into it there will be extended cost..its racing! This will be my winter project. Thanks
So that's is the back drop, now i need your guys help with my 4.8 hop up. I would like for the 4.8 to stay N/A so nothing thats crazy..im thinking 300whp in a less than 2400lbs car would be pretty quick on a road course; plus should be fairly reliable at that power level. Right now i have a complete 2003 4.8 and a Corvette z06 ls6 intake. I know i need a cam, long tube headers maybe a dry sump system and i plan to use the factory rx7 oil cooler. The engine would need to rev out to at least 7k rpm. Which cam do i need? Springs? This will be a manual so i wont have to deal with stalls and all that jazz. Lol. do i need to mill the heads to gain some hp? Trying to stay under 5k for the whole build. Of course as i get into it there will be extended cost..its racing! This will be my winter project. Thanks
08-12-2019, 01:05 PM
#2
Restricted User
Mill the stock heads at least .025"
Pick a camshaft with a 21x/22x intake duration and a 22x exhaust duration, 112-115 LSA and it'll rev to 7k on a 4.8.
Springs will depend on camshaft choice. For road racing, it might be worth it to skip straight to a double spring setup with shims if your cam has less than .600 lift.
After the cam/mill, make sure your pushrods are the correct length.
Dry sump not needed with the right oil pan baffling setup.
Easy 350-370whp 4.8.
Pick a camshaft with a 21x/22x intake duration and a 22x exhaust duration, 112-115 LSA and it'll rev to 7k on a 4.8.
Springs will depend on camshaft choice. For road racing, it might be worth it to skip straight to a double spring setup with shims if your cam has less than .600 lift.
After the cam/mill, make sure your pushrods are the correct length.
Dry sump not needed with the right oil pan baffling setup.
Easy 350-370whp 4.8.
08-12-2019, 01:07 PM
#3
http://www.ws6project.com/user_stor/...oducts_id=8670
From what ive read on here that is a AWESOME cam AND spring kit for what your trying to do since the lobes arent too aggressive. it will rev passed 7000 but be a little easier on the valve train than most. Add a trunion kit and some pushrods and your good to go.
Some of the new summit cams are supposed to be easier on the valve-train too but I would ask them about that.
And of course you can call up any of the big cam manufactures and spend some dough on what they recommend if you got it.
From what ive read on here that is a AWESOME cam AND spring kit for what your trying to do since the lobes arent too aggressive. it will rev passed 7000 but be a little easier on the valve train than most. Add a trunion kit and some pushrods and your good to go.
Some of the new summit cams are supposed to be easier on the valve-train too but I would ask them about that.
And of course you can call up any of the big cam manufactures and spend some dough on what they recommend if you got it.
08-13-2019, 04:27 PM
#5
http://www.ws6project.com/user_stor/...oducts_id=8670
From what ive read on here that is a AWESOME cam AND spring kit for what your trying to do since the lobes arent too aggressive. it will rev passed 7000 but be a little easier on the valve train than most. Add a trunion kit and some pushrods and your good to go.
Some of the new summit cams are supposed to be easier on the valve-train too but I would ask them about that.
And of course you can call up any of the big cam manufactures and spend some dough on what they recommend if you got it.
From what ive read on here that is a AWESOME cam AND spring kit for what your trying to do since the lobes arent too aggressive. it will rev passed 7000 but be a little easier on the valve train than most. Add a trunion kit and some pushrods and your good to go.
Some of the new summit cams are supposed to be easier on the valve-train too but I would ask them about that.
And of course you can call up any of the big cam manufactures and spend some dough on what they recommend if you got it.
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08-14-2019, 07:44 PM
#8
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NAVYBLUE210 (08-15-2019)
08-15-2019, 08:24 AM
#11
Just to add some more info... the track im building the car for is VIR Virginia international raceway.. its a 3 mile track with 2 long straights 18 turns.. some cars get up to 180 mph on one of those straights!
08-15-2019, 08:32 AM
#12
Restricted User
It'll probably be OK then. Mine also weighs 2400 lbs. Power comes in hard up top but its a little lazy down low.
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Ls7colorado (08-15-2019)
08-15-2019, 11:08 AM
#15
Cool, what type of valve train upgrades would you recommend.. i know the older gen 3's have issues with rockers. Ticking sound..etc this engine will be upper rpm all the time so should i upgrade rod bolts?
08-15-2019, 11:54 AM
#16
Restricted User
For the amount of time it will be at higher RPM, you'll want some stability.
I'd do rocker trunions (a couple of types to choose from), double springs with shims, hardened pushrods.
I think I would do gen 4 rods/pistons before I would go through the mess of rod bolts in gen 3 rods.
I'd do rocker trunions (a couple of types to choose from), double springs with shims, hardened pushrods.
I think I would do gen 4 rods/pistons before I would go through the mess of rod bolts in gen 3 rods.
The following users liked this post:
Ls7colorado (08-15-2019)
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Ls7colorado (08-15-2019)
08-15-2019, 12:41 PM
#20
Mill the stock heads at least .025"
Pick a camshaft with a 21x/22x intake duration and a 22x exhaust duration, 112-115 LSA and it'll rev to 7k on a 4.8.
Springs will depend on camshaft choice. For road racing, it might be worth it to skip straight to a double spring setup with shims if your cam has less than .600 lift.
After the cam/mill, make sure your pushrods are the correct length.
Dry sump not needed with the right oil pan baffling setup.
Easy 350-370whp 4.8.
Pick a camshaft with a 21x/22x intake duration and a 22x exhaust duration, 112-115 LSA and it'll rev to 7k on a 4.8.
Springs will depend on camshaft choice. For road racing, it might be worth it to skip straight to a double spring setup with shims if your cam has less than .600 lift.
After the cam/mill, make sure your pushrods are the correct length.
Dry sump not needed with the right oil pan baffling setup.
Easy 350-370whp 4.8.