upgrading to 20g, fuel/boost questions

[97redgsx]

ok so i bought a 20g over the winter because i found a really good deal. it was a little bigger than i wanted to go but the price was right. anyways, now im getting my tranny back from pruven performance next week and i am going to be driving the car...finally.

now i have a few questions regarding my new turbo:
what boost levels can i run with stock fuel?
are there any "cheap" fuel upgrades that i could stick on until i get the proper stuff just to run a couple extra psi?

i have been searching the forums for a while now on the subject and i haven't seen much on the 20g, more the t28 and 16g. however i have seen a few tims, from reliable sources, that a bigger turbo will "blow away" a t25 at 16psi at only 13-14psi.... i don't mean to sound like an idiot but how isn't 15psi the same no matter what turbo pushed it?

so far my supporting mods are:

fully rebuilt engine(stripped it to the block and replaced every bearing/seal, as well as removed the balance shafts)

tial 38mm external wastegate
MBC
1st gen BOV(crushed)

thanks for all your help guys

 

[ThingyNess]

If it's a TD05H-20g, you're going to be limited to the exact same boost levels as if it were a 14b or 16g.

You're right, for the most part, 15psi *is* the same no matter which turbo is pushing it. Compressor efficiency isn't the be-all, end-all, and a good intercooler gives you a lot of leeway here. People mistake the power gains at the same boost level from a bigger turbo as coming from the bigger compressor side, when really, the lower exhaust restriction on the turbine side is what really helps the engine's volumetric efficiency.

If you were to take a TD05H-14b, 16g, and 20g, all with the same exhaust housing (6cm or 7cm^2, take your pick) and dyno them at, say, 15psi, all with the same wastegate actuator (or external wastegate off the O2 housing), you would notice that the power level between all 3 would be virtually identical, other than the difference in boost threshold.

The reason a T25 takes a whole heck of a lot more boost to make the same power as a 14b or 16g is its ridiculously tiny exhaust wheel and housing. A TD05H turbine wheel is in and around the same size as a T3 wheel, and is way, WAY bigger than the one on the T25.

Anyway, to answer your question, you're still going to be limited to 14-16psi on the 20g on the stock fuel system, just like as if it was a 16g or a 14b.

 

[primalfear600]

aha! answers alot of questions, thanks...

also i thought id add its a hybrid 20g.

so what your saying is that i can "safely" run 16psi on this turbo?

 

[ThingyNess]

Oh, and as far as cheap fuel upgrades, one of the first things you'll want to do is rewire your stock fuel pump - that will give you a little more headroom.

You can grab a fuel pressure regulator from a non-turbo for about 10% more fuel flow, and then hack the MAS to bring everything back (close to) in line.

Really though, if you spent all the effort to go external, and rebuild your engine, some bigger injectors and dsmlink (or an SAFC if you're cheap) shouldn't really break the bank.

 

[ThingyNess]

The boost pressure level that it's safe to run is going to depend on a lot of things - how many boost leaks you have, how hot it is where you live, what sort of gas you're going to be running in it, and whether your stock fuel pump is getting old and tired. I'd rewire the fuel pump first, before anything else, and you should be relatively safe until your ECU gets annoyed and hits fuel cut. Whether that's 14psi, 18psi, or otherwise will take some experimentation to find out.

 

[primalfear600]

Really though, if you spent all the effort to go external, and rebuild your engine, some bigger injectors and dsmlink (or an SAFC if you're cheap) shouldn't really break the bank.

well, i already broke the bank, i broke it bad.... i rebuilt the engine myself which saved me a bunch, but the trans rebuild ran me a pretty good chuck of money. so my car budget is essentially zero for now.

 

[Dagda]

for a 20g, if you're going through all the trouble of rewiring it, a wally 255 is only 95 bucks shipped, with rewire kit. i understand teh bank has taken a hit, but when its starts to fill up, the 255 will be great small investment and will be able to handle anything the 20g could push out

 

[97redgsx]

sure the pump is 95 bucks but in order to run then 255 you need a FPR which is another 200 bucks....

 

[Slow99x]

You do not "need" an upgraded FPR with a 255 fuel pump. I'm on a much bigger turbo than you and with much larger injectors. I've had no problems with my stock FPR, granted I have a S-AFC to control the fuel too. An upgraded FPR is better to have but is not "needed". I would not bother putting in the 20g untill you have every other supporting mod needed to push 20+psi becuase what would be the point? It is comes into boost later and for no reason yet.

 

[Boostdclips99]

Must agree with slow99. If you don't have the supporting mods to install the 20g yet there would be no point in putting it in. It could possible cause the car to run worse. Im currently running 660s, Walbro 255 with an Aeromotive FPR tuning with an SAFC and it is not fun at all. Right now I'm limiting the boost to about 18psi until I get DSMlink to support the fuel compensation. Save up and buy the mods your interested in then install it at once. That way you don't have to keep ordering parts after you have installed something that needs another mod to make it run better.

 

[Dagda]

+1 for all supporting mods first. my buddy tried to run his evo III on stock everything excpet injectors and tuning, ### he "could" but he paid for it later down the road

 

[timloomis]

Sorry, but your going to feel the difference between 20 psi on a 14b and 20 psi on a 20g. Some has to do with the exhaust side, but mostly it's cfm from the compressor. 20 psi on a 14b and 20g will still be a huge difference with the 7cm housing.

 

[Slow99x]

Um... where did I say there wouldn't be a difference between 20psi on a 20g and 14b? I said to not put on the 20g untill he can support 20+psi on the 20g. There would be no point to doing the install untill he could run 20psi becuase the 14b is more efficient at lower boost and is more streetable with fewer mods. His lack of an upgraded exhaust would alone be choking that 20g and causing it to come into boost later.

 

[primalfear600]

apexi turbo back and a kandn cone, forgot to list it

 

[nightspeed87]

Um... where did I say there wouldn't be a difference between 20psi on a 20g and 14b? I said to not put on the 20g untill he can support 20+psi on the 20g. There would be no point to doing the install untill he could run 20psi becuase the 14b is more efficient at lower boost and is more streetable with fewer mods. His lack of an upgraded exhaust would alone be choking that 20g and causing it to come into boost later.

He ment this post

If it's a TD05H-20g, you're going to be limited to the exact same boost levels as if it were a 14b or 16g.

You're right, for the most part, 15psi *is* the same no matter which turbo is pushing it. Compressor efficiency isn't the be-all, end-all, and a good intercooler gives you a lot of leeway here. People mistake the power gains at the same boost level from a bigger turbo as coming from the bigger compressor side, when really, the lower exhaust restriction on the turbine side is what really helps the engine's volumetric efficiency.

If you were to take a TD05H-14b, 16g, and 20g, all with the same exhaust housing (6cm or 7cm^2, take your pick) and dyno them at, say, 15psi, all with the same wastegate actuator (or external wastegate off the O2 housing), you would notice that the power level between all 3 would be virtually identical, other than the difference in boost threshold.

The reason a T25 takes a whole heck of a lot more boost to make the same power as a 14b or 16g is its ridiculously tiny exhaust wheel and housing. A TD05H turbine wheel is in and around the same size as a T3 wheel, and is way, WAY bigger than the one on the T25.

Anyway, to answer your question, you're still going to be limited to 14-16psi on the 20g on the stock fuel system, just like as if it was a 16g or a 14b.

Which a lot of this could very well be accurate except I do not agree about the part were you said they will all have the same hp output at the same boost level...
I dont think the hp difference will be dramatic at say those three TDO5H turbos at 15psi youll just notice slower spool with the bigger one .
For one though, the air charge will be lower temp on the bigger turbo therefore that could be more power in itself. Also the compressor side will flow more cfm at say 15psi on the 20g than it will at 15psi on the 14b.

Have you ever seen dyno sheets were ppl make say, 340whp at 21psi on a evo3, then bolt up a 20g and make the same hp on say 17psi... ( Im just throwing out numbers right now ) Yes lower boost, but more power because more air flow ( even supposing both set ups were the same)

Its a pressure vs volume axiom

But i dont think you should be putting a 20g on a car with a stock fuel system and unless your positive you will not boost past 15psi ( good ext wastegate set up )
But even then, I just wouldnt risk it , especially without a fuel pump.
Get a 255 first ( dont worry about a afpr for the time being ) and then get your injectors and fuel tuning and then run it.

Youll be putting a bigger turbo ( spooling slower ) running it at low boost which would just make more sense to keep the stock turbo on at that point. Youd be less likely to blow your motor also that way.

 

[ThingyNess]

Which a lot of this could very well be accurate except I do not agree about the part were you said they will all have the same hp output at the same boost level...
I dont think the hp difference will be dramatic at say those three TDO5H turbos at 15psi youll just notice slower spool with the bigger one .
For one though, the air charge will be lower temp on the bigger turbo therefore that could be more power in itself. Also the compressor side will flow more cfm at say 15psi on the 20g than it will at 15psi on the 14b.

Have you ever seen dyno sheets were ppl make say, 340whp at 21psi on a evo3, then bolt up a 20g and make the same hp on say 17psi... ( Im just throwing out numbers right now ) Yes lower boost, but more power because more air flow ( even supposing both set ups were the same)

Its a pressure vs volume axiom

But i dont think you should be putting a 20g on a car with a stock fuel system and unless your positive you will not boost past 15psi ( good ext wastegate set up )
But even then, I just wouldnt risk it , especially without a fuel pump.
Get a 255 first ( dont worry about a afpr for the time being ) and then get your injectors and fuel tuning and then run it.

Youll be putting a bigger turbo ( spooling slower ) running it at low boost which would just make more sense to keep the stock turbo on at that point. Youd be less likely to blow your motor also that way.

There are indeed situations where people make, say 340whp at 21psi on an EVO3 16g, and then the same power at 17psi on a 20g. However, virtually all of these aren't apples to apples comparisons on the turbine side of things. Virtually every EVO3 is installed straight up, right out of the box from Mitsubishi. Most 20Gs are made custom, as Mitsu never actually sold a TD05H-20g "out of the box" - as such, many many 20g turbos that are sold either come with a clipped TD05H turbine wheel, or a TD06 or TD06H turbine wheel, and any of the 3 would increase turbine flow, reduce exhuast back pressure, and increase the engine's VE.

A "straight up" TD05h-20g with the same 7cm housing as an EVO3-16g will make the same power at the same boost level, so long as it's not outside the limits of the 16g's performance envelope.

Also, a bigger turbo does not necessarily mean colder air. In the midrange, it's very likely that the 16g is more efficient than the 20g, particularly when you aren't pushing the hairy edge of the EVO3's limits. Even when you are, if you have any kind of decent FMIC, the difference in charge temperatures at the engine will be less than 10 degrees C, if that. It is not very easy to pick out a 10 deg difference in charge temps on a dyno graph.

Combine that with the fact that people very often change a tune, or tweak a few things in between going from a 16g to a 20g, and finding a true comparison is quite difficult. If you know of any that are on the same car, with no changes, on the same dyno, showing a comparison between an unmodified TD05H turbine wheeled 20g in a 7cm TD05 housing versus an off the shelf EVO3-16g, I'd love to see it, though. It's fun to be proved wrong, too. Means everyone learns something.

 

[nightspeed87]

There are indeed situations where people make, say 340whp at 21psi on an EVO3 16g, and then the same power at 17psi on a 20g. However, virtually all of these aren't apples to apples comparisons on the turbine side of things. Virtually every EVO3 is installed straight up, right out of the box from Mitsubishi. Most 20Gs are made custom, as Mitsu never actually sold a TD05H-20g "out of the box" - as such, many many 20g turbos that are sold either come with a clipped TD05H turbine wheel, or a TD06 or TD06H turbine wheel, and any of the 3 would increase turbine flow, reduce exhuast back pressure, and increase the engine's VE.

^^^^This is what I was trying to get at... shouldve been more clear .

A "straight up" TD05h-20g with the same 7cm housing as an EVO3-16g will make the same power at the same boost level, so long as it's not outside the limits of the 16g's performance envelope.

I think there still should be some difference even if very small as I mentioned
but the gain would be more significant with a TDO6H, but what 20g are we talking about here for the OP?

Also, a bigger turbo does not necessarily mean colder air. In the midrange, it's very likely that the 16g is more efficient than the 20g, particularly when you aren't pushing the hairy edge of the EVO3's limits. Even when you are, if you have any kind of decent FMIC, the difference in charge temperatures at the engine will be less than 10 degrees C, if that. It is not very easy to pick out a 10 deg difference in charge temps on a dyno graph.

And this is true, at mild to mid boost the temp difference wouldnt be too noticable so you are correct. Were my point would come into better perspective is when your running the turbos up to their max efficiency point in which the bigger turbo would shine, a air charge or a turbo raises substantially upon boost and some turbos temp goes up faster than others depending on compressor, sizeing, etc.

Combine that with the fact that people very often change a tune, or tweak a few things in between going from a 16g to a 20g, and finding a true comparison is quite difficult. If you know of any that are on the same car, with no changes, on the same dyno, showing a comparison between an unmodified TD05H turbine wheeled 20g in a 7cm TD05 housing versus an off the shelf EVO3-16g, I'd love to see it, though. It's fun to be proved wrong, too. Means everyone learns something.

Im going off of a local friends experience with e316g gt turbo to a tdo6 20g turbo with changing nothing on the set up but that and running 20 psi on both...
The change was probably more significant on his case because of the higher boost level already scrapping the roof of the 16gs efficiency point.

On another situation heres an example of going to a larger turbo ( But this would be apples and oranges in comparison to the 20g arguement.)

http://www.turbomagazine.com/tech/0209tur_dyno_cell_mitsubishi_galant/index.html

But this may not all be so useful for the OP anyways...
I say for him to just not put that turbo on until he finishes his set up, patience is a virtue... Better to do it right the first time.

 

[jjneat1179]

Put the 20g on and then sell the t25 and buy your fuel pump and rewire kit with the money.It might spool slower but at 15 psi on the t25 it will not last real long i run mine on 15psi for about 3months and then the t25 took a dump.Put the 20g on and sell the t25 put the money back in your car.

 

[nightspeed87]

Put the 20g on and then sell the t25 and buy your fuel pump and rewire kit with the money.It might spool slower but at 15 psi on the t25 it will not last real long i run mine on 15psi for about 3months and then the t25 took a dump.Put the 20g on and sell the t25 put the money back in your car.

How much money do you really think hed get for a T2 small...... I think he'd be lucky to get a 100 dollars if its not brand new. IMO I say beat the crap out of the T25 till it dies and in the meantime be saving for
parts to go along with your 20g set up and install the 20g once your finished with getting
all the supporting mods you need, or either when your t25 kicks the bucket.

 

[dsm-onster]

I think there still should be some difference even if very small as I mentioned but the gain would be more significant with a TDO6H, but what 20g are we talking about here for the OP?

The key here is you think. . . . . .It's just not true. Surge is more detrimental to performance than the other end of the map WRT compressor choice. The turbines efficiency DOES NOT alter the efficiency map of the compressor. It does something far more important. Compressor efficiency is a good indicator of turbo rpm which is helpful in determining whethor or not the turbo will blow up at a given boost level and a given volume flow demand from the engine. As no turbo manufacturer would completely off-balance the flow capabilities of a turbine and compressor combination (hybrid or not). The key here is simply volume demand. If a 2.0L engine w. 272s demands 35 lb/min from a small 16G at 20 psi then it demands the same from a 20g at 20 psi. Looking at the comressor map, where does the efficiency lie between the two. Further. . . here's the calculations to get to volume flow for a simple turbo/intercooler setup:

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Doing the math you see that 10% difference (from 75% efficiency to 65% efficiency) at 23 psi and an intercooler at 75% efficiency, yields a final intake tem difference of 10 degrees F. This is a wapping 5 crank hp difference w/ a 2.0L at 7K rpms and 95% VE. Drop the intercooler efficiency 10% and see what happens . . .

And this is true, at mild to mid boost the temp difference wouldnt be too noticable so you are correct. Were my point would come into better perspective is when your running the turbos up to their max efficiency point in which the bigger turbo would shine, a air charge or a turbo raises substantially upon boost and some turbos temp goes up faster than others depending on compressor, sizeing, etc.

You're right about effect but not about cause here. . . A big turbo shines becasue it can spin at an operable rpm for boost. Either the hot side can do enough total work to maintain the particular boost w/ the compressor wheel supplied. OR, the compressor wheel is big enough to not need such high rpms to deliver the flow to the intercooler/engine system. Eitherway, operating in 60% efficiency for the compressor is not the culprit of turbo tuning. The catch is that little to no manufacturer of turbochargers will sell a compressor/turbine combination that will ALLOW the compressor to flow at 65% or lower efficiency. . . So, when you're out of your compressors range, then chances are you're out of yout turbines flow range and pressure is jsut building in the exhaust manifold and doing nothing. . . or you over spin your turbo assembly and boom !

I've gone from at the ceiling of the small16G to the midrange potential of an 18G w/ zero gain at 23 psi. W/ a cam upgrade, the small 16G COMPRESSOR is all but spent at this point . . . The TD05H wheel and 7cm^2 housing is just right for a small 16G. I begins to get in the way at the e3 16G horsepower range. . . I say that alot of guys w/ evo3 turbos could stand to gain quite a bit by swapping out 7 cm^2 housings for 8 cm^2 housings. . . Or spending the money on installing td06h turbine wheels and cutting the 7 cm^2 housings to fit. The later is more expensive than the first but both would be cheaper than upgrading the whole turbo. . . Nevertheless, there's a HUGE difference between a td05H 20G and a td06H 20G at the end of the dyno run. I ditched the 7cm^2 housing on the 18g and ran a BEP housing and noted A HUGE positive change. . .I sold all of it before heading to the track (this WAS my DD). . .

Starting w/ the small 16g and moving to the td05H 20G; the bigger the wheel, the less it has to spin to support higher boost. Consequently, indirectly more efficienct at higher boosts. . . The rest of the exhaust energy is wastegated. The turbine can only deliver so much energy to the assembly to spin the compressor. So guys upgrade compressor wheels and yield better results when boosting over 25 psi and flowing more than the next size down compressor wheel. . . It's that simple. . .to a point .

 

[dsm-onster]

How much money do you really think hed get for a T2 small...... I think he'd be lucky to get a 100 dollars if its not brand new. IMO I say beat the crap out of the T25 till it dies and in the meantime be saving for
parts to go along with your 20g set up and install the 20g once your finished with getting
all the supporting mods you need, or either when your t25 kicks the bucket.

I'd like the t2small on my automatic tranny toyota camry turbo install. . .

 

[primalfear600]

well i have no more t25 nor do i have any choice but to run the 20g....i sold it to a honda kid.

anyways, this is all very useful, i do have a good wastegate, Tial 38mm. so i wil never overboost, and i can bear to have slower spools for the meantime. i will have fun though because my T25 was not holding boost anymore.

but in the meantime in gonna grab a fuel pump. 190lph