4.8 JY build - RWHP guesses?
10-05-2016, 03:35 PM
#1
Teching In
Thread Starter
4.8 JY build - RWHP guesses? Ok, thought I would break down and write something about this build that is already over a year in the works.
May 2015 I picked up a junkyard 4.8 to basically learn the LS architecture. First time getting my feet wet with any kind of engine building. The plan was to go big right away, but keep it super low budget as possible. With this I mean not go with crap parts, but find the stuff on sale or just places getting rid of old stock. Also get supporting mods done on the motor for a turbo and just boost it as is. I stripped the entire engine other than bottom end (crank, rods, pistons) and cleaned everything and put it all back together with a few supporting parts. The block and everything else was dam near like new for 150K. Cross-hatching still visible in all 8 cylinders.
I have since gone a different direction, sort of. Since this will be the first engine and car (4th gen Firebird) I thought I should start slower and work my way up. So turbo was out for now. Only took me a year and a half to make this decision. Reason was my first born. So this will now be a family weekend vehicle to take out in the summer.
Ok, so here is the build as it sits. The engine is ready to basically be dropped into a car, minus electrical and fueling. Also here are the installed parts.
- Ls6 springs
- Stock LR4 Cam
- Typhoon intake
- Stock truck manifolds
- Ls7 lifters and guides
- Stock 862 heads
I am going to back track and do as follows.
- Cam (216/220 at .560 intake and exhaust, 114 lsa)
- Hardened pushrods
- LS2 timing chain
- New oil pump
- Longtube headers
- Full exhaust from y-pipe back (when in car)
- SLP air intake (when in car)
- 91 octane custom tune on dyno
This will be running through a 4l80e, Circle D 3000 converter, and Ford 8.8 posi rear end, 3.73s.
What do you GUESS it could make to the wheels with this setup? I am happy with anywhere from 290 - 310 rwhp. Since that is a good starting point for future mods after car is on road, like aftermarket heads, better intake (Fast LSX), and boost when the kids don't want to ride anymore.
Sorry for the book. I couldn't decide the typical "what do you think it will make" vs " here is my life story". I choose the later.
Thanks!
May 2015 I picked up a junkyard 4.8 to basically learn the LS architecture. First time getting my feet wet with any kind of engine building. The plan was to go big right away, but keep it super low budget as possible. With this I mean not go with crap parts, but find the stuff on sale or just places getting rid of old stock. Also get supporting mods done on the motor for a turbo and just boost it as is. I stripped the entire engine other than bottom end (crank, rods, pistons) and cleaned everything and put it all back together with a few supporting parts. The block and everything else was dam near like new for 150K. Cross-hatching still visible in all 8 cylinders.
I have since gone a different direction, sort of. Since this will be the first engine and car (4th gen Firebird) I thought I should start slower and work my way up. So turbo was out for now. Only took me a year and a half to make this decision. Reason was my first born. So this will now be a family weekend vehicle to take out in the summer.
Ok, so here is the build as it sits. The engine is ready to basically be dropped into a car, minus electrical and fueling. Also here are the installed parts.
- Ls6 springs
- Stock LR4 Cam
- Typhoon intake
- Stock truck manifolds
- Ls7 lifters and guides
- Stock 862 heads
I am going to back track and do as follows.
- Cam (216/220 at .560 intake and exhaust, 114 lsa)
- Hardened pushrods
- LS2 timing chain
- New oil pump
- Longtube headers
- Full exhaust from y-pipe back (when in car)
- SLP air intake (when in car)
- 91 octane custom tune on dyno
This will be running through a 4l80e, Circle D 3000 converter, and Ford 8.8 posi rear end, 3.73s.
What do you GUESS it could make to the wheels with this setup? I am happy with anywhere from 290 - 310 rwhp. Since that is a good starting point for future mods after car is on road, like aftermarket heads, better intake (Fast LSX), and boost when the kids don't want to ride anymore.
Sorry for the book. I couldn't decide the typical "what do you think it will make" vs " here is my life story". I choose the later.
Thanks!
10-05-2016, 03:54 PM
#2
TECH Addict
Welcome to the forums.
I would imagine you could safely expect 300rwhp with the 216/220 cam and the longtube headers. There is a section specifically for dyno number predictions, and this may get moved to that section. But anyways, I think you are off to a pretty good start. Keep us posted on your progress.
I would imagine you could safely expect 300rwhp with the 216/220 cam and the longtube headers. There is a section specifically for dyno number predictions, and this may get moved to that section. But anyways, I think you are off to a pretty good start. Keep us posted on your progress.