1g block with 2g pistons, Likes and dislikes

[fwdmaster]

I have a 1g turbo block that I got from a friend of mine and was thinking of going with 2g pistons. Does anyone have any experience with a 1g block with 2g pistons and what was the pros and cons in performance,thanks

 

[c4uldr0n]

The only cons would be if you didn't have the capability to "tune" the boost/timing properly. Higher compression with stock agressive 1g timing is not a great thing unless you can pull the timing back so you can run more boost. The better compression is great for lower rpm/city driving though.

 

[dontfeedphils]

I can't tell a ton of a difference, but I still haven't boosted past 10 psi since I rebuilt it. Plus I have DSMLink so I can tune it right and adjust the timing when i have to.

It's pretty cheap to upgrade so you might as well.

 

[JayRolla]

Its a very nice setup. I am only running an safc and I have to pull the base timing back a little to get a good tune at just 15psi, but I dont have a fmic installed yet. I will soon be adding e85 so I dont have to worry about the timing or high compression.

 

[Highbooost]

Honestly man, by the time you pay to have machine work done, get new rings ect ect, you could get a nice set of aftermarket pistons with better higher compression. Just something to think about, Wisecos are very good, and reasonable priced around $400.

 

[JayRolla]

It only cost me $50 to have them machined to fit. If he wanted forged pistons he might as well get forged rods also or the motor wouldnt really benifit from them.

 

[tkelly27]

Is higher compression really an upgrade? Think about what your goals are before you start down any path with the internals of your engine. For a lot of cars on the road it's a good idea, for a lot of race cars, it's not really a great idea. Lower compression will allow you to run higher boost on lower octane fuel, or more aggresive timing. Higher compression is more responsive, and can be more efficient, however the amount of boost you can run for a given octane level generally goes down.

My personal preference is low compression, because I like the ability to run 87 octane when I need too, just gotta turn the boost down There are some who feel that putting 87 octane into any turbocharged vehicle is a sin, to each their own. : D

 

[Highbooost]

The weak link in a stock motor is the pistons not the rods. The stock compression ration is garbage. So just putting in better pistons would be just as beneficial whether he did the rods of not. Rember 500 + awhp is achievable on the stock components.

It only cost me $50 to have them machined to fit. If he wanted forged pistons he might as well get forged rods also or the motor wouldnt really benifit from them.

 

[slowgsr]

Is higher compression really an upgrade? for a lot of race cars, it's not really a great idea. Lower compression will allow you to run higher boost on lower octane fuel, or more aggresive timing. Higher compression is more responsive, and can be more efficient, however the amount of boost you can run for a given octane level generally goes down.

So your running higher boost on lower compression, you must like blowing hot air into your engine? And the reason you need to run more timing and boost is to make the same power you would on a high compression engine with less boost.

The high compression engine will spool the turbo fast, make power soon and at lower boost levels.

The lower compression will spool slower, make power later and have to run more boost, so at the same power levels with the same setup, a higher compression engine will have positive pressure in the manifold sooner, and the turbo wont have to make as much boost (less heat) to produce the same power levels.

High compression - Harder to tune, faster spooling, less boost required to make the same power levels.

Lower compression - Easier to tune (more forgiving), slower spooling, more boost required to make the same amount of power (more heat).

Really, on both setups at 400whp you can use the same grade of fuel for the same power levels but the higher compression will have a better powerband and run faster ET's.

And as for needing to use 87 in your car sometimes being one of the reasons why you like 'lower compression'.. uhhh

 

[GVR4592]

Higher compression won't spool the turbo any quicker.

 

[Highbooost]

Amen, thanks exactly what I was thinking

So your running higher boost on lower compression, you must like blowing hot air into your engine? And the reason you need to run more timing and boost is to make the same power you would on a high compression engine with less boost.

The high compression engine will spool the turbo fast, make power soon and at lower boost levels.

The lower compression will spool slower, make power later and have to run more boost, so at the same power levels with the same setup, a higher compression engine will have positive pressure in the manifold sooner, and the turbo wont have to make as much boost (less heat) to produce the same power levels.

High compression - Harder to tune, faster spooling, less boost required to make the same power levels.

Lower compression - Easier to tune (more forgiving), slower spooling, more boost required to make the same amount of power (more heat).

Really, on both setups at 400whp you can use the same grade of fuel for the same power levels but the higher compression will have a better powerband and run faster ET's.

And as for needing to use 87 in your car sometimes being one of the reasons why you like 'lower compression'.. uhhh

 

[JayRolla]

The weak link in a stock motor is the pistons not the rods. The stock compression ration is garbage. So just putting in better pistons would be just as beneficial whether he did the rods of not. Rember 500 + awhp is achievable on the stock components.

Wrong, stock pistons and rods can handle 500whp on a good tune with no detonation. So no reason to upgrade just one, both rods and pistons should be done at the same time since both parts become weak links at about the same power leve.

 

[96gstdsm]

I have a 6 bolt block with 1g big rods and 2g pistons. Great combo. I like having the higher compression but having bigger rods to handle more power. Machining the rods to fit the pistons was an extra 60 bucks or so. Definitely worth doing.

 

[Highbooost]

Wrong, stock pistons and rods can handle 500whp on a good tune with no detonation.

So no reason to upgrade just one, both rods and pistons

should be done at the same time since both parts become weak links at about the same power leve.

I said that.

Unless, you want higher compression, which would be better than stock

I am not quite sure that the pistons can hold up as long as the rods as far as HP is concerned, so therefore just changing pistons again would be better, AND alot cheaper. $400-$700 for a set of rods.

 

[JayRolla]

I said that.

Unless, you want higher compression, which would be better than stock

I am not quite sure that the pistons can hold up as long as the rods as far as HP is concerned, so therefore just changing pistons again would be better, AND alot cheaper. $400-$700 for a set of rods.

Both the stock oem pistons and rods have been proven to handle up too 500whp pretty reliably. Anything past that forged would be the way to go. In my opinion running forged pistons on stock rods is a waste since the rods will start to become an issue at high hp. Why waste the money on pistons when you usually can get a good set of 2g pistons for around $50 plus $50-$60 for machining.

 

[Highbooost]

Both the stock oem pistons and rods have been proven to handle up too 500whp pretty reliably. Anything past that forged would be the way to go. In my opinion running forged pistons on stock rods is a waste since the rods will start to become an issue at high hp. Why waste the money on pistons when you usually can get a good set of 2g pistons for around $50 plus $50-$60 for machining.

You have to buy at least new rings from the dealer and they are around $130, and if you know where to get new 2g pistons for $50 a set I would like to know where. Plus maching, you are getting closer to that 400 mark.

Let me ask a question where would the stock rods give out at, my guess is around 600hp, anY feedback?

 

[JayRolla]

Usually the rod is what fails on oem motors with a lot of power, not the piston. If the tune is good the piston will last forever. 2g pistons come in 2g cars, so usually people sell them for $50 or less when they upgrade. No reason to buy new pistons.

 

[cturok7]

I am totally new to this short block business. I am almost ready to tear down my block. I want to get it rebuilt.

I personally think that the 2g piston/1g rod combo sounds like it makes sense, in theory.

I want my car to be streetable. Based on a book source, whos co-author is from RRE, this guy says that the rings on a 2g seal better and they are slightly higher in compression.

My horspower goals at MAXIMUM, at least, for now would be 300 hp. more like 250 for now since the car isn't even running ha!

there's so many mixed opinions i don't know who to believe.

Also read this book. "How to Build Max-Performance Mitsubishi 4G63t Engines"

Really good info. Not like Buscher's book. Buscher's book is just a huge advertisement, not a helpful guide like this.

 

[cturok7]

So, in the near-distant future, when I show up at a machine shop here in Greenville, South Carolina with my 1g rods and 2g pistons, what information do I give to the machinist? What kind of numbers or language should I use?

I am totally new to this.

My ultimate goal is to build a very reliable DSM. Well built. Not necessarily fast right away. Just a nice sound DSM with 50 extra horsepower to pull out every once in awhile. I like it clean.

 

[taylorspl]

See Blowup Update #4 and [1G] prop valve, 95 piston machining.

That should cover everything. The link on the VFAQ appears to be dead.

I run a 6 bolt with 2g pistons. I just dynoed at IA Performance in Tucson at 305whp and 352wtq on a s16g.