4.8 s475 how hard should i push it but keep it alive
04-28-2014, 04:02 PM
#1
4.8 s475 how hard should i push it but keep it alive I know most of this is in my other post but my question is a little more direct now.So i melted 2 pistons and broke one in my lq9 and being i have a 4.8 ill use that while a 5.3, 5.7, or a 6.0 is built. Im tired of engine changes at the point of build a engine and be done. So for now ill use the 4.8 and it has stock 862 heads good pushrods and springs and a turbo cam out of the 6.0. Cam is a little long on intake duration but if lag is to bad ill change, up but for now its going to be tried. Turbo is the 96mm 1.32 t6 housing pump gas, stock lines, boost reference regulator, 80 lb injectors, and a meth kit. Havent decided if i should do a 30/70 washer fluid mix as water is much better at heat dissipation straight meth as its good for raising octane to safer levels of high boost and knock resistance or 50/50 mix. I want to keep it somewhat on the safer side of things so it will last till the forged engine is built and ready, but i dont want to have a 11 second car. Whats everyone reccomend on meth/mix and how much boost?
04-29-2014, 07:48 AM
#2
Restricted User
It sounds like your old one gave out from excess heat and detonation, not because it couldn't handle the power you were throwing at it. The 4.8 should handle more power, so fix those problems first.
04-29-2014, 05:25 PM
#8
Restricted User
Most gen 3 rods start to have trouble around 700whp.
The 4.8 has a shorter stroke, which means less leverage on the crank and more crank overlap. Technically the 4.8 crank is the strongest.
This also means better rod/stroke ratio. Less side-load on the cylinder walls. This puts less stress on the rods and piston skirts/ring lands. The 4.8 is the ideal setup for boost. It should handle a good bit more power than the stock rods in the longer stroke setups.
There is a guy on this forum making 800whp on a bone stock 4.8. Stock cam and valve springs. The record for highest WHP on the dyno is a gen 3 4.8 that cracked 1000whp on boost and spray. Are there setups making more power? Yes. Its just the highest confirmed dyno so far.
These aren't old gen 1 small blocks. I give a pretty hard facepalm when I hear people talking about breaking rods at 400whp. Take care of it, keep the temps down as low as possible, and it'll last a lot longer than expected, even over 750whp.
Food for thought, a 4.8 crank in a 6.0 block with 6.0 pistons comes back out to around 5.3 in displacement. You get the benefit on the short stroke/high RPM 4.8 with the added displacement. You also get the ability to run LS3 heads for maximum flow. If I ever build an all-out race car, it'll use this setup.
The 4.8 has a shorter stroke, which means less leverage on the crank and more crank overlap. Technically the 4.8 crank is the strongest.
This also means better rod/stroke ratio. Less side-load on the cylinder walls. This puts less stress on the rods and piston skirts/ring lands. The 4.8 is the ideal setup for boost. It should handle a good bit more power than the stock rods in the longer stroke setups.
There is a guy on this forum making 800whp on a bone stock 4.8. Stock cam and valve springs. The record for highest WHP on the dyno is a gen 3 4.8 that cracked 1000whp on boost and spray. Are there setups making more power? Yes. Its just the highest confirmed dyno so far.
These aren't old gen 1 small blocks. I give a pretty hard facepalm when I hear people talking about breaking rods at 400whp. Take care of it, keep the temps down as low as possible, and it'll last a lot longer than expected, even over 750whp.
Food for thought, a 4.8 crank in a 6.0 block with 6.0 pistons comes back out to around 5.3 in displacement. You get the benefit on the short stroke/high RPM 4.8 with the added displacement. You also get the ability to run LS3 heads for maximum flow. If I ever build an all-out race car, it'll use this setup.
04-29-2014, 05:30 PM
#9
Most gen 3 rods start to have trouble around 700whp.
The 4.8 has a shorter stroke, which means less leverage on the crank and more crank overlap. Technically the 4.8 crank is the strongest.
This also means better rod/stroke ratio. Less side-load on the cylinder walls. This puts less stress on the rods and piston skirts/ring lands. The 4.8 is the ideal setup for boost. It should handle a good bit more power than the stock rods in the longer stroke setups.
There is a guy on this forum making 800whp on a bone stock 4.8. Stock cam and valve springs. The record for highest WHP on the dyno is a gen 3 4.8 that cracked 1000whp on boost and spray. Are there setups making more power? Yes. Its just the highest confirmed dyno so far.
These aren't old gen 1 small blocks. I give a pretty hard facepalm when I hear people talking about breaking rods at 400whp. Take care of it, keep the temps down as low as possible, and it'll last a lot longer than expected, even over 750whp.
Food for thought, a 4.8 crank in a 6.0 block with 6.0 pistons comes back out to around 5.3 in displacement. You get the benefit on the short stroke/high RPM 4.8 with the added displacement. You also get the ability to run LS3 heads for maximum flow. If I ever build an all-out race car, it'll use this setup.
The 4.8 has a shorter stroke, which means less leverage on the crank and more crank overlap. Technically the 4.8 crank is the strongest.
This also means better rod/stroke ratio. Less side-load on the cylinder walls. This puts less stress on the rods and piston skirts/ring lands. The 4.8 is the ideal setup for boost. It should handle a good bit more power than the stock rods in the longer stroke setups.
There is a guy on this forum making 800whp on a bone stock 4.8. Stock cam and valve springs. The record for highest WHP on the dyno is a gen 3 4.8 that cracked 1000whp on boost and spray. Are there setups making more power? Yes. Its just the highest confirmed dyno so far.
These aren't old gen 1 small blocks. I give a pretty hard facepalm when I hear people talking about breaking rods at 400whp. Take care of it, keep the temps down as low as possible, and it'll last a lot longer than expected, even over 750whp.
Food for thought, a 4.8 crank in a 6.0 block with 6.0 pistons comes back out to around 5.3 in displacement. You get the benefit on the short stroke/high RPM 4.8 with the added displacement. You also get the ability to run LS3 heads for maximum flow. If I ever build an all-out race car, it'll use this setup.
04-29-2014, 05:37 PM
#10
Restricted User
Water is incredible heat dissipation. Not only does it take a fair amount of energy to raise the temps of water, but its latent heat of vaporization means it takes a lot to force it to change phase. This causes it to draw out a LOT of excess heat.
Meth increases the octane and burns cooler and cleaner than gasoline. I've seen pistons look like they're almost new when pulling the heads before after running a large nozzle on the water/meth.
You have to be sure not to run too much water or meth. They can pool in the intake. Water can hydrolock and meth can backfire, but a 50/50 mix should prevent this. Too much water can also draw out too much heat and lead to torque loss. In the right amount, it can actually provide a slight torque boost as it will greatly expand when going from water to steam.
Most people run a 50/50 to keep a good balance between the two for good reason. You really shouldn't mess with the ratio unless you have a reason to want one more than the other, or are mixing additives in with them.
Meth increases the octane and burns cooler and cleaner than gasoline. I've seen pistons look like they're almost new when pulling the heads before after running a large nozzle on the water/meth.
You have to be sure not to run too much water or meth. They can pool in the intake. Water can hydrolock and meth can backfire, but a 50/50 mix should prevent this. Too much water can also draw out too much heat and lead to torque loss. In the right amount, it can actually provide a slight torque boost as it will greatly expand when going from water to steam.
Most people run a 50/50 to keep a good balance between the two for good reason. You really shouldn't mess with the ratio unless you have a reason to want one more than the other, or are mixing additives in with them.
04-30-2014, 09:59 AM
#12
Honestly I had a 06 lq9 that bent two rods when it trashed 3 pistons. Not sure how that happened. They were the gen 4 rods also. When I build this next one, forged rods and pistons and have it balanced I think ill start with the 6.0 block and go with minimal over bore, ls3 heads and intake combo. People seem to have great luck with this combo
Last edited by dans94z28; 04-30-2014 at 01:49 PM.
04-30-2014, 11:24 AM
#13
Restricted User
Honestly I had a 06 lq9 that bent two rids when it trashed 3 pistons. Not sure how that happened. They were the gen 4 rods also. When I build this next one, forged rods and pistons and have it balanced I think ill start with the 6.0 block and go with minimal over bore, ls3 heads and intake combo. People seem to have great luck with this combo
04-30-2014, 11:38 AM
#14
11 Second Club
iTrader: (3)
Join Date: Jun 2011
Location: Scottsdale, AZ
Posts: 344
Likes: 0
Received 0 Likes
on
0 Posts
Honestly I had a 06 lq9 that bent two rids when it trashed 3 pistons. Not sure how that happened. They were the gen 4 rods also. When I build this next one, forged rods and pistons and have it balanced I think ill start with the 6.0 block and go with minimal over bore, ls3 heads and intake combo. People seem to have great luck with this combo
04-30-2014, 01:51 PM
#15
I didn't mean 4 it to sound like too much power attributing to it being bent I'm more or less wondering why it then along with the Pistons melting more so I can avoid whatever caused the issue in the future if it was detonation change up the tuner etc
Last edited by dans94z28; 04-30-2014 at 02:09 PM.
04-30-2014, 02:06 PM
#16
tons of variables
that said 14psi 14deg is a magic number for nearly everything i tune on pumpgas
once you have methanol i push harder like 18-22lbs and 12deg, i push up carefully and watch dyno numbers or trap speed
11.30 AFR TR6 spark plug
had many 9-10sec stock bottom end cars so far without problem
or about a year or more of passes before bent rod or so, sometimes no problem at all.
that said 14psi 14deg is a magic number for nearly everything i tune on pumpgas
once you have methanol i push harder like 18-22lbs and 12deg, i push up carefully and watch dyno numbers or trap speed
11.30 AFR TR6 spark plug
had many 9-10sec stock bottom end cars so far without problem
or about a year or more of passes before bent rod or so, sometimes no problem at all.
04-30-2014, 02:16 PM
#17
TECH Fanatic
Id say on 93 you could go to 20psi. Keep it rich and don't get greedy on timing. I ran my stock ls1 stock compression to 23psi and it never blew up. Same turbo.
04-30-2014, 03:46 PM
#20
My last engine we were supposed to meet up and tune it but you were headed to cecil and i was working some crazy hours so our schexule never lined up. I think ill be happy with it at 15 psi it sounds like and anything over that is just bonus. Car has already been 10.29 at 134 on 10 lbs on a ebay turbo so really excited to see how the bw does since everyone has such good luck with them.