2G Boost Limits?

[Concepts]

Another basic post, I'm just wondering how much boost the engine can take with a GReddy FV2 BOV, a 3" exhaust system (unsure if that matters), 650cc injectors (unsure if that matters), and 264 cams (unsure if that matters). If there are other things that you need to account for in the motor that I'm missing, mention it and I'll tell you if I'm leaving it stock or not. I'd be rocking a 68HTA, 20G, or a big 16G, if that matters. Another question to go with this, does lb/min directly correlate to how much psi the turbo can push out, and does that mean more power on less psi (probably not but worth asking)? Thanks

 

[fwdmaster]

Are you talking about 6 bolt or 7 bolt engines? As for the turbo flow/lbs/minute,each turbo is different.

 

[Purevil]

Your asking the wrong question. Boost isn't how anyone rates an engines strength. 20psi on a 16g and 20psi on a 35r are not equal even though they are both 20psi, the volume of air is greater on the 35r and both turbos at 20psi will produce completely different amounts power. You need to figure out what you want to do with the car and the amount of horsepower that will make you happy. Then base your setup on that plan.

 

[chrisman287]

I’d say it depends on how your engine was maintained and it’s condition, the maintenance you do before modding and the tune after modding.

 

[pauleyman]

You're putting the cart before the horse.

Please read the site FAQs, guides, how to's etc.
I urge you to read this.

Project management and building a dsm

I wrote this for another board some time ago and wanted to share it here.Project management.......Over the years we keep hearing opinions of this or that, how to build something etc but we rarely see something broken down (no pun intended) to more basic terms. I have been dealing with...

www.dsmtuners.com

 

[Concepts]

Are you talking about 6 bolt or 7 bolt engines? As for the turbo flow/lbs/minute,each turbo is different.

I'm talking about the 7-bolt. Other responses have also said that, regarding turbo flow, and I saw information about flow being greater on other turbos when reading descriptions.

Your asking the wrong question. Boost isn't how anyone rates an engines strength. 20psi on a 16g and 20psi on a 35r are not equal even though they are both 20psi, the volume of air is greater on the 35r and both turbos at 20psi will produce completely different amounts power. You need to figure out what you want to do with the car and the amount of horsepower that will make you happy. Then base your setup on that plan.

You're right, engine strength isn't rated by boost. I've also seen others talk about the volume of air. I've already made a build plan, which I've talked about with other people in a previous post, and I'm just wondering how much psi I should put into the engine without causing issues, because there is a limit for everything. This isn't a good question to ask, however, because I don't have more information. I am wondering how much psi I should put into the engine with a turbo with similar flow to the 20G. That general area is what type of turbo I'm getting.

I’d say it depends on how your engine was maintained and it’s condition, the maintenance you do before modding and the tune after modding.

That makes sense.

You're putting the cart before the horse.

Please read the site FAQs, guides, how to's etc.
I urge you to read this.

Project management and building a dsm

I wrote this for another board some time ago and wanted to share it here.Project management.......Over the years we keep hearing opinions of this or that, how to build something etc but we rarely see something broken down (no pun intended) to more basic terms. I have been dealing with...

www.dsmtuners.com

I will look into this page now. Thanks for the information.

I just read the page and I'm going to go ahead and fill out the "template" that you provided.

What constraints do you have? School, money
Money? Probably a $15,000 budget. Not a lot for a build like what I want, but something to get me started. Most of it is going into the car.
Time? Weekends and weekdays that I don't feel like doing anything else.
Choice of car etc (maybe you want something rare) 2G Eclipse GS-T or GSX
Skill? Manuals and research is my friend. I am relatively new to the entire car community, however, my dad is a really good mechanic, and could help me with just about anything.
I prefer much more objective goals and the list can get lengthy and specific

Goals:
- Around 300-400hp, very broad spectrum
- Daily driveable
- Pump gas, nothing special. It's probably almost impossible to hit 400hp on pump gas judging by what some say, but it's worth a shot getting close
- Something nice to look at (body, interior, AND under the hood)

 

[chrysler kid]

I mean you can pay as much money for a setup as your want, but you need to find a tuner who can match your parts to engine management.

Buying the parts isnt a problem, but they need active engine management which some shops in the south absolutely refuse to do for these cars. Then the fuel management and engine tuning fall back on your responsibility.

Your dad may have mechanic skills, but unless he can set fuel data tables that build is going to spin a crank bearing downing the piston rings in fuel

 

[Concepts]

I mean you can pay as much money for a setup as your want, but you need to find a tuner who can match your parts to engine management.

Buying the parts isnt a problem, but they need active engine management which some shops in the south absolutely refuse to do for these cars. Then the fuel management and engine tuning fall back on your responsibility.

Your dad may have mechanic skills, but unless he can set fuel data tables that build is going to spin a crank bearing downing the piston rings in fuel

- Alright
- Alright
- Manual fuel pressure regulator?

I'm not asking about my build, I'm asking how much boost the 4g63 motor can handle in general, with more information regarding the key parts of my build, just in case that matters.

 

[Spleen8urLSX]

Not to bash you here but you’re still asking the same question but with the wording in different order, and the answer doesn’t change. Boost is irrelevant, the things you listed off are irrelevant to how much your engine can hold, however they are relevant in helping make power, so you have your goal of 300-400 in mind so what you need to look at is “will my parts along with fuel choice make the power I want, if not what needs changed” followed by “can my engine hold the power likely, if not what needs to change”.

I will say first and foremost, what engine management are you controlling it all with? If you have no means to tune go ahead and take the 650cc injectors off the table now as we know one can’t simply drop bigger injectors in with no way to control them. To add to that though, those 650s will be about useless on e85 though they may be enough to see 400 on pump gas, lots of variables there, however 300 on those is not at all out of the realm of possibility.

You pretty much get where I’m going here, a lot of things you can determine or decide but nothing that anyone can give you an exact number on. To put it into perspective, I once made 420 at the wheels on an evo3 16g spiking 28psi and falling off to 24psi on e85 on a bone stock 130k mile non turbo 6 bolt bottom end. Was this the ONLY way to do this? No. Was it the right way to do it? Probably not. Should everyone do it that way and expect it to work because it worked for me? Definitely not. But did it work and hold power for quite some time? Sure did.

Now go learn what you can and run with it. Pick the parts based off the research you do and know if your parts will all work together, if they work together then you find out if they do what you want them to do, if they don’t then you make changes. What I will say is none of the turbos you listed are likely to see 400 on pump gas.

 

[chrysler kid]

- Alright
- Alright
- Manual fuel pressure regulator?

I'm not asking about my build, I'm asking how much boost the 4g63 motor can handle in general, with more information regarding the key parts of my build, just in case that matters.

A stock t25 turbo can only generate 18psi. The turbo itself can not flow more pressure than that rating.

The stock ecu will only tolerate a certain cfm rating before it generates a fuel cut. So the max psi is determined by the ecu not the engine

The stock 14b turbo on a 1st gen can generate up to 25 psi. You could try to get more pressure from it, but it would max out its capacity around there. Then You would need to change the fuel and air management settings to allow the ecu to properly accept that much air flow

A large turbo will generate more airflow at 18psi than a stock turbo at 18psi

So the answer to your question can not be answered in your terms. The answer is specifically rated to the size of the turbo charger and its ability to flow higher air at the same boost pressure.

The generalized answer is the stock bottom end can only hold 450hp reliably. That 450hp can come at 40 psi on a small turbo, or 20psi on a large turbo. Its a variable dependant on the size of the turbo.

On a basic car, lets say a stock internal honda, they typically tell you that its only safe to run 7psi or something low, but because the 4g63 already has strengthened internals they run 14psi stock. The small turbochargers on them can only make around 20psi before they can not flow enough air to overcome the suction of the motor at a higher rpm range. So you would upgrade the turbo to run hihher psi

 

[Spleen8urLSX]

A stock t25 turbo can only generate 18psi. The turbo itself can not flow more pressure than that rating.

The stock ecu will only tolerate a certain cfm rating before it generates a fuel cut. So the max psi is determined by the ecu not the engine

The stock 14b turbo on a 1st gen can generate up to 25 psi. You could try to get more pressure from it, but it would max out its capacity around there. Then You would need to change the fuel and air management settings to allow the ecu to properly accept that much air flow

A large turbo will generate more airflow at 18psi than a stock turbo at 18psi

So the answer to your question can not be answered in your terms. The answer is specifically rated to the size of the turbo charger and its ability to flow higher air at the same boost pressure.

The generalized answer is the stock bottom end can only hold 450hp reliably. That 450hp can come at 40 psi on a small turbo, or 20psi on a large turbo. Its a variable dependant on the size of the turbo.

On a basic car, lets say a stock internal honda, they typically tell you that its only safe to run 7psi or something low, but because the 4g63 already has strengthened internals they run 14psi stock. The small turbochargers on them can only make around 20psi before they can not flow enough air to overcome the suction of the motor at a higher rpm range. So you would upgrade the turbo to run hihher psi

Correct in some points and incorrect in others. Take the 14b for example, I’ve seen some cars it’s still making power at that 24-25psi, other set ups I’ve seen them do nothing but blow hot air after 20-21psi. Same with the t25, some cases it will make 18psi (I should say spike at 18psi as I’ve never seen one actually hold that) and I’ve seen a few that wont even hit that. BUT, other than determining exact numbers which there are too many variables to determine you have the right mindset.

As far as a boost level “x engine can hold x amount of boost” you’re absolutely correct that came from the Honda crowd years ago. Hell I read countless threads on here from years ago “non turbo pistons won’t hold anything more than stock boost on a 14b or else the ring lands will crack!!” by a bunch of folks who clearly never did it and because so many people said it 20 years ago people STILL swear off that though it’s been disproven. To be exact I got to 454 on pump gas at 22psi on a Borg s363, had every intention of trying to crack 600 on e85 but never got back to the dyno after the great oil filter incident of 2020.

Another prime example (and again these are extreme cases not saying everyone can expect the same results but just to give an idea of variances we are in this topic) the stock bottom end record car made MUCH more than that 450 at the wheels, through an auto trans (reads significantly lower on a dyno typically) on an untouched 6 bolt with over 230k miles on it that’s been in about 5 other DSM’s since the car it originated in over a 12 year span. I won’t say what the car made on Kevin Jewers dyno as that’s Erik’s business to share and to me dyno numbers are irrelevant anyway aside from the fun factor, but the car trapped 151mph on that engine so that tells you something right there.

Moral of the story, don’t buy into the “x engine can hold x amount of power” or “x engine can hold x amount of boost”, there’s so many variables including huge advances in tuning technology since many of these theories were thought of that we have more than proven to ourselves those numbers are just a myth. People like to think of a “safe” number but many of the tuning errors that could lead a stock bottom end making say 600 at the wheels fail can just as easily make one fail making 300 at the wheels.

 

[Concepts]

Correct in some points and incorrect in others. Take the 14b for example, I’ve seen some cars it’s still making power at that 24-25psi, other set ups I’ve seen them do nothing but blow hot air after 20-21psi. Same with the t25, some cases it will make 18psi (I should say spike at 18psi as I’ve never seen one actually hold that) and I’ve seen a few that wont even hit that. BUT, other than determining exact numbers which there are too many variables to determine you have the right mindset.

As far as a boost level “x engine can hold x amount of boost” you’re absolutely correct that came from the Honda crowd years ago. Hell I read countless threads on here from years ago “non turbo pistons won’t hold anything more than stock boost on a 14b or else the ring lands will crack!!” by a bunch of folks who clearly never did it and because so many people said it 20 years ago people STILL swear off that though it’s been disproven. To be exact I got to 454 on pump gas at 22psi on a Borg s363, had every intention of trying to crack 600 on e85 but never got back to the dyno after the great oil filter incident of 2020.

Another prime example (and again these are extreme cases not saying everyone can expect the same results but just to give an idea of variances we are in this topic) the stock bottom end record car made MUCH more than that 450 at the wheels, through an auto trans (reads significantly lower on a dyno typically) on an untouched 6 bolt with over 230k miles on it that’s been in about 5 other DSM’s since the car it originated in over a 12 year span. I won’t say what the car made on Kevin Jewers dyno as that’s Erik’s business to share and to me dyno numbers are irrelevant anyway aside from the fun factor, but the car trapped 151mph on that engine so that tells you something right there.

Moral of the story, don’t buy into the “x engine can hold x amount of power” or “x engine can hold x amount of boost”, there’s so many variables including huge advances in tuning technology since many of these theories were thought of that we have more than proven to ourselves those numbers are just a myth. People like to think of a “safe” number but many of the tuning errors that could lead a stock bottom end making say 600 at the wheels fail can just as easily make one fail making 300 at the wheels.

A stock t25 turbo can only generate 18psi. The turbo itself can not flow more pressure than that rating.

The stock ecu will only tolerate a certain cfm rating before it generates a fuel cut. So the max psi is determined by the ecu not the engine

The stock 14b turbo on a 1st gen can generate up to 25 psi. You could try to get more pressure from it, but it would max out its capacity around there. Then You would need to change the fuel and air management settings to allow the ecu to properly accept that much air flow

A large turbo will generate more airflow at 18psi than a stock turbo at 18psi

So the answer to your question can not be answered in your terms. The answer is specifically rated to the size of the turbo charger and its ability to flow higher air at the same boost pressure.

The generalized answer is the stock bottom end can only hold 450hp reliably. That 450hp can come at 40 psi on a small turbo, or 20psi on a large turbo. Its a variable dependant on the size of the turbo.

On a basic car, lets say a stock internal honda, they typically tell you that its only safe to run 7psi or something low, but because the 4g63 already has strengthened internals they run 14psi stock. The small turbochargers on them can only make around 20psi before they can not flow enough air to overcome the suction of the motor at a higher rpm range. So you would upgrade the turbo to run hihher psi

Thank you both for the information. I am definitely going to do more research and see what's right for me