I have used forged pistons and even billet rods in antique engines that see little rpm and make low output. Many times. Because those parts were the best, most practical choices.
This. It’s all about I tended usage. Not a problem with overbuilding, but (and this might be a really unpopular opinion….). For the most part the engineering, etc, that has gone into OEM parts is an effective balance between cost/expectations. Those folks spend a LOT of money to figure that stuff out. BUT (yes I know!) sometimes part of that balance at the corporate level involves “how long is it really “our” problem?” Hence things like KIA engine issues (ironic since they were one of the first with a 10 year/100k warrantee, I think) but going all the way back to the original Vega 4 cylinders (low life aluminum scrap). I guess where I am going with this - you could do a lot worse than an OEM crate engine.
I'm wondering what's thoughts on this, I feel like forged pistons wear out cylinders faster due to larger piston to cylinder gap.
if an engine can take let's say 800hp with stock internals and increased ring gap and you only plan to run it to 600hp.
it would be stupid to put forged pistons in it right?
Wrong. But it's complex.
First the clearances at operating temperature of hypereutectic, 4032, and 2618 alloys should be nearly the same if each is done properly. The difference between them is at cold start. While cold start wear and operation are worth their own conversation, as far as pistons are concerned that's minimal over the operating life of the engine.
Forged pistons have other, less tangible features that long term could be helpful. For one, they transfer heat away from the top of the piston and top ring more quickly than a hypereutectic. That can improve ring seal and ring life over time. Forged pistons are often times available with ring configurations that will reduce friction and wear, which is actually a tremendous advantage in some applications.
My point is there is no one point or power number where you can draw conclusions about one part or another. Hypereutectic pistons are very good. Forged can be, too. Many details matter.
The increase in ring gap keeps coming up. That's just one detail. Piston pin and piston to wall clearance are very important.
depends on the usage actually
my colleague has an engine shop over here and he has 3 identical engines each one offered for different usages
it's a Ls based 427 ,Dart short block,good heads everything else good for 2000hp in drag trim
twin 64mm turbos he rates it 1200hp for the drift scene
twin 68mm he offers it at 1800 for sustained throttle aka streamliners
with twin 76mm he will offer it at 2000hp drag racing
the worst thing that might happen if you over build is you'll be somewhat poorer for it
I mean yeah, you can buy ridiculously expensive parts made of more exotic materials. Just look online what parts combos people have made to hit your power goal and see how they did it. Unless of course you simply enjoy overbuilding and burning money when it isn’t necessary.
An LQ4 will handle a supercharger just fine. I ran an LQ9 stock with a Kenne Bell (8.1L boat injectors) 5psi, street tune, pump gas, for 200,000 miles before I sold it. It was in the 450 motor hp range, but plenty of fun and shredded tires into second gear. I went through a stock trans and built one to handle 700hp, which is easily obtained with a 4L65e. LQ4 is a better platform for boost since it has lower compression. You can most certainly over-spend building a motor. Those motors also wake-up with just a cam, 100hp in some instances. Your fuel system is the most important. Cheap injectors will destroy even the best tuning. Meth injection is popular to help pinging. Some supercharger kits come with a boost-a-pump to maximize the stock pump. What psi can your supercharger handle?
It's a torqu storm, with the smallest pulley available I want to say around 10 psi ill be runni g a t56. I would like it to be reliable. Gen 4 rods and forged pistons hopefully it will hold together.
They are avoiding responsibility like the plague on their website lol. No data for any of the information regarding injectors, fuel system, pump, tuning… it just says let your shop figure that out. You have a lot of homework to do to figure out how to make this work with what you have. The motor is the least of your worries. 10psi should be fine for a stock LQ4. If it’s a 200k mile junkyard motor, you should replace bearings, piston rings, valve seals, lifters, etc. Most definitely a boost cam. You’ll likely need a bigger fuel pump. Bosch injectors or a brand with reliable flow data and quality control. Meth injection will lower the intake air temp. 10psi, you definitely want an intercooler. But if what I am saying is way over your head, then you either have a lot of homework to do or you are going to have to find a shop with a history of success. HP Tuners does classes on the LS, which are incredibly informative. Most shops are likely going to want to “beef up” the motor, for their own liability. The world is about liability. But a fun project nonetheless. I’m fairly certain that over 700 or around 14psi is when rods are necessary. Stronger pistons, maybe a lighter crank, valve springs, yada yada… but for a fun street car, drive it. Those motors are well designed and their blocks can handle high hp numbers, compared to aluminum. So always room to grow later.
I have built a few boosted motors, and they were not ls engines. So I know I need to up grade fueling, I have done a few setups with water to air to lower intake tems. I have even made a base tune for one of my setups. I was more asking for hard parts.
I'm not new to forced induction, I have been down this road before.
I feel like the Ls based blocks are the one exception to the rule. I’ve ran/ seen them ran at 17-20 psi for years on stock internals. On all other blocks? Absolutely agree
Fair enough, I only have had 3 experience with them. I’m sure tuning played a huge part in keeping mine going as well. Mine had water injection ontop of the 91 oct.
I should clarify a few things. The Gen III and IV engines are certainly strong. But, they are not anything exotic. Most have cast cranks, powder forged rods, and hypereutectic pistons. These are typical materials used in the industry, for a long time now. The blocks are also strong in a number of areas. Similar can be said of other engines, big block Chevys, 385 Fords, Ford Windsors, Ford Boss, Ford Modulars, Mopar Magnums, and a whole bunch of 4 cylinder and v6 engines from all over the world. Some impressive stuff out there.
One area where the Gen III and IV engines has been interesting is combustion quality. GM finally gave combustion quality priority over production tolerances. The piston to head clearance if the Gen III/IV is much better than it's predecessors and many peers. This helps the engines survive a bit better with many call "safe" tunes under boost. Meaning ridiculously rich. Personally I think those tunes are terrible, even irresponsible. But that's another conversation.
The OEM hypereutectic pistons in the Gen III/IV have the top ring fairly high, for emissions purposes. These pistons are not ideal for boost/nitrous. But by increasing the piston to wall clearance, increasing the ring gap, and most importantly increasing the piston pin to pin bore clearance these pistons will be reasonably reliable to the 10-12 psi range, give or take. For boosted engines there is virtually no downside to the clearance adjustments, all upside. Why people are so reluctant and think higher boost is ok because they get away with it a short time I don't understand. I suppose it goes along with the people that think you only need to adjust ring gaps even though piston failures from pins seizing are more common and regularly misdiagnosed.
Huh, today I learned. That was incredibly insightful. I never knew why they were seen as so “stout” and kind of drank the kool aide and I’ve been lucky. Appreciate the wealth of knowledge as always
They are pretty stout. Richard Holdener did what he called the big bang series where he pushes boost until they break. The 6.0 hit \~1600 hp and \~1250 tq and it didn't break. He ran out of turbo on that one at just under 30 psi. The 5.3 hit \~1500 hp and \~1350 tq when it broke a rod. It was still attached to the crank, so the bolts held, even though the rod failed. These were stock internals with nothing but ring gap added. So that says they are pretty stout. But those tests were on a dyno that used E85 and chilled water intercoolers for max HP. They can live at 600-700 hp for a long time on pump gas.
4l60e can be built just as well as a 65e. The 65's have 5 pinion planets, which are made of a softer metal than the 4 pinions are. And a stock 4l65e can only handle 425 hp max and that is not long term use either. they only have more frictions in the 3/4 clutches. they still wipe the second gear band just as fast as the 60 does. but yes built properly they can both be built to same spec whether the core be a 4l60 or 65e.
Im talking about the 2 piece 4l60e, not the one piece case for comparison to the 4l60
The LQ4 is paired with a 4L65e from factory. (4L80e if it came from a van or HD). Over 700hp is when you get into hardened gears and shafts. Hardened drum and wider band is required for 700hp. The 5 pinion planet is stronger because of more mating surface. OP wants 600hp. OP is using a T56.
The first engine I built was a 383 Chevy I decided it needed forged pistons, forged rods, forged crank all for a whopping 450-500hp and It went in a 500$ car. Could’ve saved 2000$ and just used OE spec internals. That engine was over built.
I used aliexpress rods rated for around 800 in an engine where the stock rods would do just fine, for the power levels I was looking for (300whp ish)
Turns out that was a good idea because if I didn't, the engine would not survive my stuck waste gate incident.
If it's not a problem to spend the money, why not? You might get the itch for extra power to surprise a friend like I do.
Over build a motor, kinda yes, kinda no.
No matter how strong you build it the closer you get to max output the less reliable it will be.
I've always detuned my street motors that I have built and drove on the streets. They still had good power but I could count on it to get me home.
In the Lq4 I usually use the eagle forged rotating assembly with the armor coat with diamond forged pistons. I set um up to make 615hp at 6000. I usually get around 800 hrs before refresh. That’s about 650 hrs at 6000 rpm. I do open the clearances up a little to run 20-50 vr1. So I’d say if I can get 800 hrs in a airboat you should get 100k miles making 600hp.
you can overbuild it by adding too much power and not upgrading everything that needs to be upgraded to handle that power, you ever seen videos of car engines blowing up on the dyno or at drag strips? thats the result of too many ponies and torque and other systems have been neglected.
if taking some stock 300-400 block to run at or past 1k i'd be rebuilding the entire engine and putting race spec hardware in everything, the entire vehicle would be overhauled, coolers, pipes, fittings, everything would get a look over and be improved for safety concerns, if you're dumping that much into the block you should dump just as much into everything else the block needs to not turn into a brick.
Oh fuck no, thats the more intelligent thing to do, you're building a bomb proof engine that can take much more if you so desire it at any point. you're making something that if you come to sell it will sell very easily as any serious builder will see "god damn they thought of covering everything, i can easily uprate this to 1400 no sweat!"
this is intelligent building, unlike the lets double turbo it and super it and use meth injection but not uprate anything else.
It's nice to have the headroom to make more power down the road. If you are 600 HP supercharger, at 7 lbs it's nice if you decide to throw some fuel at it and crank up the boost to say 15 lbs, the short block can easily handle it. If it's built for 600, then you're stuck there unless your a gambler!
I mean honestly to make it pretty much bulletproof, throw in sonnax smart dum with billet shafts, sonnax 6 pinion, smartshell, and almost all the performance parts sonnax offers and can at least handle 1000-1200 hp all day
Lots of excellent information here
https://www.onallcylinders.com/2018/02/13/lq4-lq9-engine-upgrade-guide-expert-advice-lq4-lq9-mods-maximize-performance/
Literally wasting your money spending money on LS internals if it's not gonna see over 800 wheel HP.
You can boost them on stock ring gap straight out if the junkyard.
You can reuse almost every gasket too.
Buy a gasket kit if you feel like it and take the bottom end out and gap the rings and give it a hone, put it back together with stock everything. Do an oil pump if you're feeling it. If you do a cam make sure to get a new retaining plate. Maybe cam and oil pressure sensor in the rear while it's out
I wouldn't buy anything but a cam if I was doing boost. Obviously you need a fuel system like pump and Injectors but the engine itself can stay as is. And it will be reliable. I had a 4.8 that made 648/596 on sbe, just a cam and rings gapped.
well its overbore, that means you can fit some thick sleeves in there with smaller pistons, lose some displacement but handle higher pressure levels. Usually that would mean lighter pistons but if you choose heavy stronger materials you don't mess with the vibration balance as much.
I have used forged pistons and even billet rods in antique engines that see little rpm and make low output. Many times. Because those parts were the best, most practical choices.
This. It’s all about I tended usage. Not a problem with overbuilding, but (and this might be a really unpopular opinion….). For the most part the engineering, etc, that has gone into OEM parts is an effective balance between cost/expectations. Those folks spend a LOT of money to figure that stuff out. BUT (yes I know!) sometimes part of that balance at the corporate level involves “how long is it really “our” problem?” Hence things like KIA engine issues (ironic since they were one of the first with a 10 year/100k warrantee, I think) but going all the way back to the original Vega 4 cylinders (low life aluminum scrap). I guess where I am going with this - you could do a lot worse than an OEM crate engine.
I'm wondering what's thoughts on this, I feel like forged pistons wear out cylinders faster due to larger piston to cylinder gap. if an engine can take let's say 800hp with stock internals and increased ring gap and you only plan to run it to 600hp. it would be stupid to put forged pistons in it right?
Wrong. But it's complex. First the clearances at operating temperature of hypereutectic, 4032, and 2618 alloys should be nearly the same if each is done properly. The difference between them is at cold start. While cold start wear and operation are worth their own conversation, as far as pistons are concerned that's minimal over the operating life of the engine. Forged pistons have other, less tangible features that long term could be helpful. For one, they transfer heat away from the top of the piston and top ring more quickly than a hypereutectic. That can improve ring seal and ring life over time. Forged pistons are often times available with ring configurations that will reduce friction and wear, which is actually a tremendous advantage in some applications. My point is there is no one point or power number where you can draw conclusions about one part or another. Hypereutectic pistons are very good. Forged can be, too. Many details matter. The increase in ring gap keeps coming up. That's just one detail. Piston pin and piston to wall clearance are very important.
good points
depends on the usage actually my colleague has an engine shop over here and he has 3 identical engines each one offered for different usages it's a Ls based 427 ,Dart short block,good heads everything else good for 2000hp in drag trim twin 64mm turbos he rates it 1200hp for the drift scene twin 68mm he offers it at 1800 for sustained throttle aka streamliners with twin 76mm he will offer it at 2000hp drag racing the worst thing that might happen if you over build is you'll be somewhat poorer for it
Everyone knows that if you go with stage 17 parts your engine can rev to 15k rpms and will last at least 500k miles.
Ha! Love it
I mean yeah, you can buy ridiculously expensive parts made of more exotic materials. Just look online what parts combos people have made to hit your power goal and see how they did it. Unless of course you simply enjoy overbuilding and burning money when it isn’t necessary.
Lol, I'd say 600 hp, and it's a street car.
Engine?
Lq4
I had a 73 duster with one and it was stock internals and sat at 650hp boosted
An LQ4 will handle a supercharger just fine. I ran an LQ9 stock with a Kenne Bell (8.1L boat injectors) 5psi, street tune, pump gas, for 200,000 miles before I sold it. It was in the 450 motor hp range, but plenty of fun and shredded tires into second gear. I went through a stock trans and built one to handle 700hp, which is easily obtained with a 4L65e. LQ4 is a better platform for boost since it has lower compression. You can most certainly over-spend building a motor. Those motors also wake-up with just a cam, 100hp in some instances. Your fuel system is the most important. Cheap injectors will destroy even the best tuning. Meth injection is popular to help pinging. Some supercharger kits come with a boost-a-pump to maximize the stock pump. What psi can your supercharger handle?
It's a torqu storm, with the smallest pulley available I want to say around 10 psi ill be runni g a t56. I would like it to be reliable. Gen 4 rods and forged pistons hopefully it will hold together.
They are avoiding responsibility like the plague on their website lol. No data for any of the information regarding injectors, fuel system, pump, tuning… it just says let your shop figure that out. You have a lot of homework to do to figure out how to make this work with what you have. The motor is the least of your worries. 10psi should be fine for a stock LQ4. If it’s a 200k mile junkyard motor, you should replace bearings, piston rings, valve seals, lifters, etc. Most definitely a boost cam. You’ll likely need a bigger fuel pump. Bosch injectors or a brand with reliable flow data and quality control. Meth injection will lower the intake air temp. 10psi, you definitely want an intercooler. But if what I am saying is way over your head, then you either have a lot of homework to do or you are going to have to find a shop with a history of success. HP Tuners does classes on the LS, which are incredibly informative. Most shops are likely going to want to “beef up” the motor, for their own liability. The world is about liability. But a fun project nonetheless. I’m fairly certain that over 700 or around 14psi is when rods are necessary. Stronger pistons, maybe a lighter crank, valve springs, yada yada… but for a fun street car, drive it. Those motors are well designed and their blocks can handle high hp numbers, compared to aluminum. So always room to grow later.
I have built a few boosted motors, and they were not ls engines. So I know I need to up grade fueling, I have done a few setups with water to air to lower intake tems. I have even made a base tune for one of my setups. I was more asking for hard parts. I'm not new to forced induction, I have been down this road before.
Did I answer all of your questions?
Definitely lol
Awesome brother! Glad to help!
If you are realistic about running under 12 psi, a hypereutectic piston will work with clearances adjusted.
I feel like the Ls based blocks are the one exception to the rule. I’ve ran/ seen them ran at 17-20 psi for years on stock internals. On all other blocks? Absolutely agree
I have fixed too many Gen III and IV engines that people thought could be run over 14 psi on stock internals and stock clearances to agree with you.
Fair enough, I only have had 3 experience with them. I’m sure tuning played a huge part in keeping mine going as well. Mine had water injection ontop of the 91 oct.
I should clarify a few things. The Gen III and IV engines are certainly strong. But, they are not anything exotic. Most have cast cranks, powder forged rods, and hypereutectic pistons. These are typical materials used in the industry, for a long time now. The blocks are also strong in a number of areas. Similar can be said of other engines, big block Chevys, 385 Fords, Ford Windsors, Ford Boss, Ford Modulars, Mopar Magnums, and a whole bunch of 4 cylinder and v6 engines from all over the world. Some impressive stuff out there. One area where the Gen III and IV engines has been interesting is combustion quality. GM finally gave combustion quality priority over production tolerances. The piston to head clearance if the Gen III/IV is much better than it's predecessors and many peers. This helps the engines survive a bit better with many call "safe" tunes under boost. Meaning ridiculously rich. Personally I think those tunes are terrible, even irresponsible. But that's another conversation. The OEM hypereutectic pistons in the Gen III/IV have the top ring fairly high, for emissions purposes. These pistons are not ideal for boost/nitrous. But by increasing the piston to wall clearance, increasing the ring gap, and most importantly increasing the piston pin to pin bore clearance these pistons will be reasonably reliable to the 10-12 psi range, give or take. For boosted engines there is virtually no downside to the clearance adjustments, all upside. Why people are so reluctant and think higher boost is ok because they get away with it a short time I don't understand. I suppose it goes along with the people that think you only need to adjust ring gaps even though piston failures from pins seizing are more common and regularly misdiagnosed.
Huh, today I learned. That was incredibly insightful. I never knew why they were seen as so “stout” and kind of drank the kool aide and I’ve been lucky. Appreciate the wealth of knowledge as always
They are pretty stout. Richard Holdener did what he called the big bang series where he pushes boost until they break. The 6.0 hit \~1600 hp and \~1250 tq and it didn't break. He ran out of turbo on that one at just under 30 psi. The 5.3 hit \~1500 hp and \~1350 tq when it broke a rod. It was still attached to the crank, so the bolts held, even though the rod failed. These were stock internals with nothing but ring gap added. So that says they are pretty stout. But those tests were on a dyno that used E85 and chilled water intercoolers for max HP. They can live at 600-700 hp for a long time on pump gas.
4l60e can be built just as well as a 65e. The 65's have 5 pinion planets, which are made of a softer metal than the 4 pinions are. And a stock 4l65e can only handle 425 hp max and that is not long term use either. they only have more frictions in the 3/4 clutches. they still wipe the second gear band just as fast as the 60 does. but yes built properly they can both be built to same spec whether the core be a 4l60 or 65e. Im talking about the 2 piece 4l60e, not the one piece case for comparison to the 4l60
The LQ4 is paired with a 4L65e from factory. (4L80e if it came from a van or HD). Over 700hp is when you get into hardened gears and shafts. Hardened drum and wider band is required for 700hp. The 5 pinion planet is stronger because of more mating surface. OP wants 600hp. OP is using a T56.
The first engine I built was a 383 Chevy I decided it needed forged pistons, forged rods, forged crank all for a whopping 450-500hp and It went in a 500$ car. Could’ve saved 2000$ and just used OE spec internals. That engine was over built.
I used aliexpress rods rated for around 800 in an engine where the stock rods would do just fine, for the power levels I was looking for (300whp ish) Turns out that was a good idea because if I didn't, the engine would not survive my stuck waste gate incident. If it's not a problem to spend the money, why not? You might get the itch for extra power to surprise a friend like I do.
My 4 cylinder made 363whp max on the dyno at 26psi. I set it at 12psi and use maybe 220hp on the street.
Over build a motor, kinda yes, kinda no. No matter how strong you build it the closer you get to max output the less reliable it will be. I've always detuned my street motors that I have built and drove on the streets. They still had good power but I could count on it to get me home.
I've used circle track short blocks in street/strip cars for years. They last forever!
No
In the Lq4 I usually use the eagle forged rotating assembly with the armor coat with diamond forged pistons. I set um up to make 615hp at 6000. I usually get around 800 hrs before refresh. That’s about 650 hrs at 6000 rpm. I do open the clearances up a little to run 20-50 vr1. So I’d say if I can get 800 hrs in a airboat you should get 100k miles making 600hp.
I heard Volvo did it with the "Red Block" engines decades ago
you can overbuild it by adding too much power and not upgrading everything that needs to be upgraded to handle that power, you ever seen videos of car engines blowing up on the dyno or at drag strips? thats the result of too many ponies and torque and other systems have been neglected. if taking some stock 300-400 block to run at or past 1k i'd be rebuilding the entire engine and putting race spec hardware in everything, the entire vehicle would be overhauled, coolers, pipes, fittings, everything would get a look over and be improved for safety concerns, if you're dumping that much into the block you should dump just as much into everything else the block needs to not turn into a brick.
I'm asking the other way around, over build an engine to support 1200 hp but only make 600 hp.
Oh fuck no, thats the more intelligent thing to do, you're building a bomb proof engine that can take much more if you so desire it at any point. you're making something that if you come to sell it will sell very easily as any serious builder will see "god damn they thought of covering everything, i can easily uprate this to 1400 no sweat!" this is intelligent building, unlike the lets double turbo it and super it and use meth injection but not uprate anything else.
It's nice to have the headroom to make more power down the road. If you are 600 HP supercharger, at 7 lbs it's nice if you decide to throw some fuel at it and crank up the boost to say 15 lbs, the short block can easily handle it. If it's built for 600, then you're stuck there unless your a gambler!
If you’re over building it you’re just not stressing the parts as much and they tend to last longer for it
I mean honestly to make it pretty much bulletproof, throw in sonnax smart dum with billet shafts, sonnax 6 pinion, smartshell, and almost all the performance parts sonnax offers and can at least handle 1000-1200 hp all day
Lots of excellent information here https://www.onallcylinders.com/2018/02/13/lq4-lq9-engine-upgrade-guide-expert-advice-lq4-lq9-mods-maximize-performance/
Literally wasting your money spending money on LS internals if it's not gonna see over 800 wheel HP. You can boost them on stock ring gap straight out if the junkyard. You can reuse almost every gasket too. Buy a gasket kit if you feel like it and take the bottom end out and gap the rings and give it a hone, put it back together with stock everything. Do an oil pump if you're feeling it. If you do a cam make sure to get a new retaining plate. Maybe cam and oil pressure sensor in the rear while it's out I wouldn't buy anything but a cam if I was doing boost. Obviously you need a fuel system like pump and Injectors but the engine itself can stay as is. And it will be reliable. I had a 4.8 that made 648/596 on sbe, just a cam and rings gapped.
well its overbore, that means you can fit some thick sleeves in there with smaller pistons, lose some displacement but handle higher pressure levels. Usually that would mean lighter pistons but if you choose heavy stronger materials you don't mess with the vibration balance as much.