Most compression you’d run on boost
Tried running 12psi in a SBE stock ring gaps LS1 with 92 octane fuel at approx 10.7:1 compression. It would not take any timing at all without showing knock. Single digits of timing. There were some bad decisions I made with the build but was having fun still at the same time. I knew the engine would fail at some point in time but I really thought it would just break a ring land or maybe crack a sleeve.
It ended up completely destroying itself after it butted the rings. I wasn't mad but definitely frustrated at the amount of secondary damage. Learned a lot from the incident.
It ended up completely destroying itself after it butted the rings. I wasn't mad but definitely frustrated at the amount of secondary damage. Learned a lot from the incident.
But after a few of yall experts looked at the pistons it was decided that it looked like it butted the rings and the rods snatched the wrist pins right out of the bottom. It looks like it ripped the number 1 wrist pin out which then was carried around by the rod and snagged the number 2 rod which then ripped that wrist pin out of the number 2 piston.
The scariest part of the whole event was when it windowed the block the engine ran away even with the throttle closed. Had to shut it off with the key. I have no idea the RPMs it turned.
Holy crap I've never seen that kind of failure before, but it's hard to imagine that the rings butting up could have enough force to rip the bottom of the piston off with the wrist pin. That's wild...
A couple good pump gas data points on the upper end of the curve. Had a previous motor that I ran 22+ psig on pump gas at ~8:1 compression. I turned it up over time, but that motor held together for, I think, 18 years and 50k miles at 800+ HP. Timing was in the high teens.
My current motor runs 8:6:1 and is at ~20 psig on 93 octane at ~16 deg timing. About 5k miles and seems to be holding up just fine at ~900 WHP.
Teching In
Joined: Jan 2020
Posts: 15
Likes: 11
I'm running 10psi through a 7275 turbo on my 11.2:1 compression LS2 with stock ring gaps on 91 octane pump gas. I make 607whp and 626tq. I dunno why guys have such a hard time tuning high compression setups. Just use good detcans and listen for bad news.
Either the ring held it, or there wasn't enough piston to wall clearance.
I have readily available E85 here in Iowa and I also use meth injection. Even though I don't need it I really like the meth injection. Out of curiosity why don't those of you without access to e85 run meth injection?
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Seen too many people lose healthy engines to a faulty meth pump. Ive heard that pumps have gotten alot better recently and ive heard BMW is using it on some of their cars as well. What pump do you run?
So, rather than run meth I just drop the static compression to something low and run a ton of boost. From what I've seen, you end up in a pretty similar spot from a power standpoint (<5% difference?) without the added complexity.
For the same reasons I run an air-to-air vs. air-to-water. Over time, I've learned that on a regularly driven street car, simpler is typically better.
So, rather than run meth I just drop the static compression to something low and run a ton of boost. From what I've seen, you end up in a pretty similar spot from a power standpoint (<5% difference?) without the added complexity.
So, rather than run meth I just drop the static compression to something low and run a ton of boost. From what I've seen, you end up in a pretty similar spot from a power standpoint (<5% difference?) without the added complexity.
I'm not saying you're wrong just trying to understand why more people don't use meth injection when it's such a simple way to add octane/cooling.
I put about 4000 miles on my car last year which is the most I've put on it in a year since owning it. I'm up to 34,000 miles on the chassis now.
I use an AEM pump, stewart warner pressure switch, tapped windshield washer tank, snow hoses, fittings, check valve, and nozzles. I mix heet in my washer fluid. Cheap effective setup. I've heard of failed meth kits on the internet, but not seen one fail personally. I think the internet makes things seem more prevalent than they really are. Many people use the same pressure switch and relays to turn on secondary fuel pumps with no concern, but using the same relay, pressure switch, and a quality pump for a meth system scares people.
I have seen push lock fittings fail and start fires for those that use 100% meth. (happened to me once as well). I don’t see it as any more/less reliable than a fuel pump. You can setup AFR safeties, pressure safeties, charge temp safeties…etc. Then your chance of a melt down with meth injection is almost zero. I’ll say 100% is where its it if you are looking for m maximizing performance. But there is also something to be said for 50/50 kits safety wise. Ive run some sort of meth/water inj. On every FI car I’ve ever owned. They plain work, and can be made relatively cheaply. No reason not to run one that I’m aware of. As a side bonus they keep your engine and ring lands really clean.
I will say, I've only ever played with 1 car with Meth injection. Some of you guys gave me some really good advice when I started tuning on it. As I was "getting my feet wet" I pulled the charge tube and sprayed it, full M1. The cooling effect it has was absolutely amazing. Tune was cold to the touch, and that was if I remember a week before LS Fest, so probably 85* ambient temp.
It isn't just the unreliability of the meth system. It's the meth system + the wet cooler pump + the hobs switch + the redundant fuel pump +, +, +. It's pretty easy to end up in a spot where you have a decent collection of switches and bits of potential hidden failures where if any one component fails before you go WOT you may drive over parts.
In heavy industry, aircraft, space, etc... there is a whole science behind failure points that will never resonate with this crowd, but as an example: If you have five widgets on your car where a failure of that device can occur before you go WOT (and you don't know about it) and each of those widgets work 999 out of 1000 times, the odds of you having a potential engine ending event for a daily driver (5 days a week, 12 months a year) is ~100% within the first year. The probabilities get pretty bad, pretty quickly.
If you don't drive the car that much, great - all that added complexity will never catch up to you. Or, if this is a race car and you test everything before a track day, also great, it is no longer a hidden failure. There is a reason a lot of folks have some sort of anecdotal story about a friend or themselves where a hobbs switch or a meth pump took out an engine - it isn't because they were unlucky or bought a bad system, its because it doesn't take a lot of these types of devices on a regularly driven car to make a failure very probable.
In heavy industry, aircraft, space, etc... there is a whole science behind failure points that will never resonate with this crowd, but as an example: If you have five widgets on your car where a failure of that device can occur before you go WOT (and you don't know about it) and each of those widgets work 999 out of 1000 times, the odds of you having a potential engine ending event for a daily driver (5 days a week, 12 months a year) is ~100% within the first year. The probabilities get pretty bad, pretty quickly.
If you don't drive the car that much, great - all that added complexity will never catch up to you. Or, if this is a race car and you test everything before a track day, also great, it is no longer a hidden failure. There is a reason a lot of folks have some sort of anecdotal story about a friend or themselves where a hobbs switch or a meth pump took out an engine - it isn't because they were unlucky or bought a bad system, its because it doesn't take a lot of these types of devices on a regularly driven car to make a failure very probable.
It isn't just the unreliability of the meth system. It's the meth system + the wet cooler pump + the hobs switch + the redundant fuel pump +, +, +. It's pretty easy to end up in a spot where you have a decent collection of switches and bits of potential hidden failures where if any one component fails before you go WOT you may drive over parts.
In heavy industry, aircraft, space, etc... there is a whole science behind failure points that will never resonate with this crowd, but as an example: If you have five widgets on your car where a failure of that device can occur before you go WOT (and you don't know about it) and each of those widgets work 999 out of 1000 times, the odds of you having a potential engine ending event for a daily driver (5 days a week, 12 months a year) is ~100% within the first year. The probabilities get pretty bad, pretty quickly.
If you don't drive the car that much, great - all that added complexity will never catch up to you. Or, if this is a race car and you test everything before a track day, also great, it is no longer a hidden failure. There is a reason a lot of folks have some sort of anecdotal story about a friend or themselves where a hobbs switch or a meth pump took out an engine - it isn't because they were unlucky or bought a bad system, its because it doesn't take a lot of these types of devices on a regularly driven car to make a failure very probable.
In heavy industry, aircraft, space, etc... there is a whole science behind failure points that will never resonate with this crowd, but as an example: If you have five widgets on your car where a failure of that device can occur before you go WOT (and you don't know about it) and each of those widgets work 999 out of 1000 times, the odds of you having a potential engine ending event for a daily driver (5 days a week, 12 months a year) is ~100% within the first year. The probabilities get pretty bad, pretty quickly.
If you don't drive the car that much, great - all that added complexity will never catch up to you. Or, if this is a race car and you test everything before a track day, also great, it is no longer a hidden failure. There is a reason a lot of folks have some sort of anecdotal story about a friend or themselves where a hobbs switch or a meth pump took out an engine - it isn't because they were unlucky or bought a bad system, its because it doesn't take a lot of these types of devices on a regularly driven car to make a failure very probable.
Not sure how many switches you need to turn on in your daily driver to where a meth kit that is activated with the ignition on pushes you over your personal comfort level for failure points, but no one is trying to convince you to use meth.
We are simply stating it's a solid option for guys that only have pump gas available and might need or benefit from the extra octane/cooling that meth injection provides. It only runs when in boost so you can literally daily drive the car all year and never have it kick on, so they really don't wear out with such a limited use to only come on at a set boost level. There are plenty of protections you can put in as well in the tune so if it doesn't come on it's not fatal to the engine.
I will say, I've only ever played with 1 car with Meth injection. Some of you guys gave me some really good advice when I started tuning on it. As I was "getting my feet wet" I pulled the charge tube and sprayed it, full M1. The cooling effect it has was absolutely amazing. Tune was cold to the touch, and that was if I remember a week before LS Fest, so probably 85* ambient temp.
The amount of heat that can be drawn out of an object is determined by the amount of time its in contact with the fluid. Since the intake is stationary every droplet that hits it, pulls a small amount of heat from it. Over time, this leads to frosty pipes. So people think that means the air charge must be as cold as the pipe/intake. That’s not the case.
The amount of time the air is exposed to the meth is in milliseconds. The temp of the intake/charge pipe/etc. has very little to do with the air temp. Very few of the air molecules come in contact with the fluid and there is almost no time for the fluid to pull heat form the air charge before its in the cylinders and out the tail pipes. Typical water/meth volumes do diddly for air charge temps. They do most of their work in the CC adding octane and slowing the flame front. Think of water/meth as race gas, not a charge cooler. It mainly up’s the detonation threshold. Esp. 50/50 mixes.
You can also only drop the charge temp to near the boiling point of the fluid. (aka 150* with 100% meth) To really impact the air charge, you’d have to spray 100% meth in VERY high volumes. Almost no one does that. The formula is something crazy like 8gph for every 1000hp worth of air flow will drop 15* off the total charge temp. So if your charge temps were say 300* and you wanted to get them down to around 150. You’d need to inject 80gph+.
Last edited by Forcefed86; Jan 3, 2024 at 02:16 PM.
It isn't just the unreliability of the meth system. It's the meth system + the wet cooler pump + the hobs switch + the redundant fuel pump +, +, +. It's pretty easy to end up in a spot where you have a decent collection of switches and bits of potential hidden failures where if any one component fails before you go WOT you may drive over parts.
In heavy industry, aircraft, space, etc... there is a whole science behind failure points that will never resonate with this crowd, but as an example: If you have five widgets on your car where a failure of that device can occur before you go WOT (and you don't know about it) and each of those widgets work 999 out of 1000 times, the odds of you having a potential engine ending event for a daily driver (5 days a week, 12 months a year) is ~100% within the first year. The probabilities get pretty bad, pretty quickly.
If you don't drive the car that much, great - all that added complexity will never catch up to you. Or, if this is a race car and you test everything before a track day, also great, it is no longer a hidden failure. There is a reason a lot of folks have some sort of anecdotal story about a friend or themselves where a hobbs switch or a meth pump took out an engine - it isn't because they were unlucky or bought a bad system, its because it doesn't take a lot of these types of devices on a regularly driven car to make a failure very probable.
In heavy industry, aircraft, space, etc... there is a whole science behind failure points that will never resonate with this crowd, but as an example: If you have five widgets on your car where a failure of that device can occur before you go WOT (and you don't know about it) and each of those widgets work 999 out of 1000 times, the odds of you having a potential engine ending event for a daily driver (5 days a week, 12 months a year) is ~100% within the first year. The probabilities get pretty bad, pretty quickly.
If you don't drive the car that much, great - all that added complexity will never catch up to you. Or, if this is a race car and you test everything before a track day, also great, it is no longer a hidden failure. There is a reason a lot of folks have some sort of anecdotal story about a friend or themselves where a hobbs switch or a meth pump took out an engine - it isn't because they were unlucky or bought a bad system, its because it doesn't take a lot of these types of devices on a regularly driven car to make a failure very probable.
And in addition to that, additional safeties can be put into place that would *usually* save the motor in the event of any one of those systems failing.
If you place an IAT sensor near your injection point it will report crazy low false charge temps. This means you can setup the tune/safety to add/pull timing/boost via the IAT tables. If for some reason the meth inj didn’t activate, the low temps wouldn’t ever register so timing/boost wouldn’t be added.
TECH Enthusiast
Joined: Mar 2013
Posts: 503
Likes: 39
Unfortunately a cold pipe/intake manifold doesn’t mean anything. Same deal with E85 and carb guys. Its a super common misconception. The volumes the typical Water meth kits use do diddly for charge temps. Charge cooling is not why water meth is so great.
The amount of heat that can be drawn out of an object is determined by the amount of time its in contact with the fluid. Since the intake is stationary every droplet that hits it, pulls a small amount of heat from it. Over time, this leads to frosty pipes. So people think that means the air charge must be as cold as the pipe/intake. That’s not the case.
The amount of time the air is exposed to the meth in in milliseconds. The temp of the intake/charge pipe/etc. has very little to do with the air temp. Very few of the air molecules come in contact with the fluid and there is almost no time for the fluid to pull heat form the air charge before its in the cylinders and out the tail pipes. Typical water/meth volumes do diddly for air charge temps. They do most of their work in the CC adding octane and slowing the flame front. Think of water/meth as race gas, not a charge cooler. It mainly up’s the detonation threshold. Esp. 50/50 mixes.
You can also only drop the charge temp to near the boiling point of the fluid. (aka 150* with 100% meth) To really impact the air charge, you’d have to spray 100% meth in VERY high volumes. Almost no one does that. The formula is something crazy like 8gph for every 1000hp worth of air flow will drop 15* off the total charge temp. So if your charge temps were say 300* and you wanted to get them down to around 150. You’d need to inject 80gph+.
The amount of heat that can be drawn out of an object is determined by the amount of time its in contact with the fluid. Since the intake is stationary every droplet that hits it, pulls a small amount of heat from it. Over time, this leads to frosty pipes. So people think that means the air charge must be as cold as the pipe/intake. That’s not the case.
The amount of time the air is exposed to the meth in in milliseconds. The temp of the intake/charge pipe/etc. has very little to do with the air temp. Very few of the air molecules come in contact with the fluid and there is almost no time for the fluid to pull heat form the air charge before its in the cylinders and out the tail pipes. Typical water/meth volumes do diddly for air charge temps. They do most of their work in the CC adding octane and slowing the flame front. Think of water/meth as race gas, not a charge cooler. It mainly up’s the detonation threshold. Esp. 50/50 mixes.
You can also only drop the charge temp to near the boiling point of the fluid. (aka 150* with 100% meth) To really impact the air charge, you’d have to spray 100% meth in VERY high volumes. Almost no one does that. The formula is something crazy like 8gph for every 1000hp worth of air flow will drop 15* off the total charge temp. So if your charge temps were say 300* and you wanted to get them down to around 150. You’d need to inject 80gph+.
Unfortunately a cold pipe/intake manifold doesn’t mean anything. Same deal with E85 and carb guys. Its a super common misconception. The volumes the typical Water meth kits use do diddly for charge temps. Charge cooling is not why water meth is so great.
The amount of heat that can be drawn out of an object is determined by the amount of time its in contact with the fluid. Since the intake is stationary every droplet that hits it, pulls a small amount of heat from it. Over time, this leads to frosty pipes. So people think that means the air charge must be as cold as the pipe/intake. That’s not the case.
The amount of time the air is exposed to the meth is in milliseconds. The temp of the intake/charge pipe/etc. has very little to do with the air temp. Very few of the air molecules come in contact with the fluid and there is almost no time for the fluid to pull heat form the air charge before its in the cylinders and out the tail pipes. Typical water/meth volumes do diddly for air charge temps. They do most of their work in the CC adding octane and slowing the flame front. Think of water/meth as race gas, not a charge cooler. It mainly up’s the detonation threshold. Esp. 50/50 mixes.
You can also only drop the charge temp to near the boiling point of the fluid. (aka 150* with 100% meth) To really impact the air charge, you’d have to spray 100% meth in VERY high volumes. Almost no one does that. The formula is something crazy like 8gph for every 1000hp worth of air flow will drop 15* off the total charge temp. So if your charge temps were say 300* and you wanted to get them down to around 150. You’d need to inject 80gph+.
The amount of heat that can be drawn out of an object is determined by the amount of time its in contact with the fluid. Since the intake is stationary every droplet that hits it, pulls a small amount of heat from it. Over time, this leads to frosty pipes. So people think that means the air charge must be as cold as the pipe/intake. That’s not the case.
The amount of time the air is exposed to the meth is in milliseconds. The temp of the intake/charge pipe/etc. has very little to do with the air temp. Very few of the air molecules come in contact with the fluid and there is almost no time for the fluid to pull heat form the air charge before its in the cylinders and out the tail pipes. Typical water/meth volumes do diddly for air charge temps. They do most of their work in the CC adding octane and slowing the flame front. Think of water/meth as race gas, not a charge cooler. It mainly up’s the detonation threshold. Esp. 50/50 mixes.
You can also only drop the charge temp to near the boiling point of the fluid. (aka 150* with 100% meth) To really impact the air charge, you’d have to spray 100% meth in VERY high volumes. Almost no one does that. The formula is something crazy like 8gph for every 1000hp worth of air flow will drop 15* off the total charge temp. So if your charge temps were say 300* and you wanted to get them down to around 150. You’d need to inject 80gph+.