g25 550 turbo

[stelllios]

Hello

I am planning to buy the g25 550 turbo but i am confused with the turbine housing. I am between 0.49 and 0.72 housing. Anyone here with 0.49 housing? Any spool results with cams or not? I saw a lot st's with 0.72 and assume is a little bit laggy. Thats a daily car not a race car.

 

[MO15Fiesta]

If you plan to daily drive the car and don't plan on more than 400whp, get the s280. I had a .72 ar G25 on my old Fiesta, it was definitely soft down low. the .49 may be better but in reality it's still a LOT of turbo for a 1.6L that doesn't turn a whole lot of rpm.

 

[stelllios]

I want something like 380-390bhp not more. I dont want an s280 because this turbo cant handle this power. Secondly i am between 2860 gen2 and g25 but g25 is more efficient turbo

 

[MO15Fiesta]

I want something like 380-390bhp not more. I dont want an s280 because this turbo cant handle this power. Secondly i am between 2860 gen2 and g25 but g25 is more efficient turbo

The s280 can absolutely handle that power and well beyond. Mine makes more than that with just upgraded direct injectors. You will be disappointed if you get a G25 and only run that amount of power as they don't start to shine until 30+psi.

 

[Mycooking]

You'll definetly be better off with the 280. Spools quicker and good top end. You will have to upgrade your fueling if you haven't already though to hit those power figures. The fuel system becomes weak sauce at about 300hp+.

 

[stelllios]

Why you tell about 30+ psi for g25 turbo? The compressor map of this turbo tells that the efficient area of this turbo is around 25 psi.

 

[jeffreylyon]

The s280 can absolutely handle that power and well beyond. Mine makes more than that with just upgraded direct injectors.

No HPFP?

 

[MO15Fiesta]

No HPFP?

Correct.

 

[esp_martin]

Why you tell about 30+ psi for g25 turbo? The compressor map of this turbo tells that the efficient area of this turbo is around 25 psi.

others please step in if I'm wrong but this seems like basic physics. if the s280's most efficient range is in the 25+ psi, then a bigger volume turbo would need more psi to reach the same efficiency. so @MO15Fiesta saying the g25 turbo needs to push 30+ psi makes sense to me when every other variable is the same.

is this right? i'm not pushing back on @stelllios just saying what @MO15Fiesta says makes sense to me but I'm still learning.

 

[MO15Fiesta]

The G25 turbo is very efficient and once it gets into boost, it's great. The "issue" is getting into boost. It's laggy and takes some time. On my old set up it would take until 4500rpm or so in normal temperatures, slightly less if it was cool, to get into boost. The s280 spools over 1000rpm earlier. If the two were to race each other, the extra 1k rpm of boost time would be a massive difference.

 

[jeffreylyon]

Correct.

You're making more than 380bhp (340whp-ish) without an upgraded HPFP or aux fuel?

 

[esp_martin]

You're making more than 380bhp (340whp-ish) without an upgraded HPFP or aux fuel?

he posted in another thread that he was pushing 330+whp with an s280 with just uprated injectors. i remember bc other people pointed out that usually means 315ish whp but he said he hasn't done anything out of the ordinary for his build but was getting those numbers. (i'm assuming this was all on e30 but can't swear on it and don't want to go combing through posts to confirm)

 

[TyphoonFiST]

Journal bearing Vs. Ball bearing...it's not a hard decision. I have a DHM360R/ Gen2 GTX2860R with a .52 TIAL SS housing and spool is fantastic. Either Turbo is a good choice! Pick your poison. But the bigger the Turbine/exhaust housing the later the spool.....FYI. Back pressure isn't your friend either with a BIG turbo.

 

[TyphoonFiST]

The G25 turbo is very efficient and once it gets into boost, it's great. The "issue" is getting into boost. It's laggy and takes some time. On my old set up it would take until 4500rpm or so in normal temperatures, slightly less if it was cool, to get into boost. The s280 spools over 1000rpm earlier. If the two were to race each other, the extra 1k rpm of boost time would be a massive difference.

The G25 or Gen2 2860 will spool about the same with the smaller exhaust housing. I am proof of this now and a firm believer in what I run now.

 

[thecman02]

Stellios, there is a disappointing amount of hard data compiled on these setups. I tried looking online at anyone that ran the t25 .49 vs the vband .72 . There wasn't anything in any forums with numbers. I saw some guys spit balling hypothesis on a Miata forum, but most threads died last year with no numbers. I also haven't seen anything on our cars that have back to back comparisons on cams. Unfortunately our engines get unreliable in the 400whp and there hasn't been any shops really throwing down, or sharing data. I do recommend following Dizzy once he gets his new block built with Mountune V2 cams. https://www.fiestastforum.com/threads/engine-build-v1-0.28912/page-3

With all that being said, s280 can make the power you want on ethanol blend, and the g25 can also make it, although it is going to be lazier and hit full boost around 400-500 rpm after (estimated) with small turbine housing compared to s280's 3500ish full spool. The .72 is most likely going to be around 4400, but might be able to make the power you seek on just premium 93 due to less drive(back) pressure and higher VE. I'd really like to see someone do a pump gas max effort car, but its a lot of money and not much incentive(return on investment) to explore things. I'm grateful for any shops or individuals that care to share their results.


My ideal setup I'd love to see someone do would be a sleeved darton block, some i-beam con rods, dual valve spring, custom high lift camshafts with upgraded HPFP lobes, custom pistons with lower CR around 9.0 to 1. Tubular manifold with a back to back dyno session with different turbine housings. A guy can dream i guess? My buddies shop has been building Can-AM x3's and we've been exploring the limits of the engine and making bespoke parts. Side by side owners seem to have much more discretional income though. I hate to sound old, but Fiesta's are just so good around 300whp that their isn't much of a market to reinvent the wheel.

*edit* i attached compressor map incase people wanted to reference it without having to google it.

 

[@Salty_FiST]

Journal bearing Vs. Ball bearing...it's not a hard decision. I have a DHM360R/ Gen2 GTX2860R with a .52 TIAL SS housing and spool is fantastic. Either Turbo is a good choice! Pick your poison. But the bigger the Turbine/exhaust housing the later the spool.....FYI. Back pressure isn't your friend either with a BIG turbo.

So tell us cause I'm not sure it has been mentioned before. What was the spool like before and after the .52 TIAL SS housing? Numbers and details if you could.

Sent from my SM-S908U using Tapatalk

 

[TyphoonFiST]

So tell us cause I'm not sure it has been mentioned before. What was the spool like before and after the .52 TIAL SS housing? Numbers and details if you could.

Sent from my SM-S908U using Tapatalk

Let me ask my Hillbilly Tuner to clarify the information of when it all starts to hit/ spool* and get back to this.

 

[MO15Fiesta]

You're making more than 380bhp (340whp-ish) without an upgraded HPFP or aux fuel?

It's right around that. Vdyno shows 346whp/337tq on a road that is gps verified less than 1% negative slope. I've not had it on an actual dyno but I don't believe that would tell any more accurate. My trap speed at the drag strip is identical to my hybrid that made 348whp/351wtq.

 

[MO15Fiesta]

Stellios, there is a disappointing amount of hard data compiled on these setups. I tried looking online at anyone that ran the t25 .49 vs the vband .72 . There wasn't anything in any forums with numbers. I saw some guys spit balling hypothesis on a Miata forum, but most threads died last year with no numbers. I also haven't seen anything on our cars that have back to back comparisons on cams. Unfortunately our engines get unreliable in the 400whp and there hasn't been any shops really throwing down, or sharing data. I do recommend following Dizzy once he gets his new block built with Mountune V2 cams. https://www.fiestastforum.com/threads/engine-build-v1-0.28912/page-3

With all that being said, s280 can make the power you want on ethanol blend, and the g25 can also make it, although it is going to be lazier and hit full boost around 400-500 rpm after (estimated) with small turbine housing compared to s280's 3500ish full spool. The .72 is most likely going to be around 4400, but might be able to make the power you seek on just premium 93 due to less drive(back) pressure and higher VE. I'd really like to see someone do a pump gas max effort car, but its a lot of money and not much incentive(return on investment) to explore things. I'm grateful for any shops or individuals that care to share their results.


My ideal setup I'd love to see someone do would be a sleeved darton block, some i-beam con rods, dual valve spring, custom high lift camshafts with upgraded HPFP lobes, custom pistons with lower CR around 9.0 to 1. Tubular manifold with a back to back dyno session with different turbine housings. A guy can dream i guess? My buddies shop has been building Can-AM x3's and we've been exploring the limits of the engine and making bespoke parts. Side by side owners seem to have much more discretional income though. I hate to sound old, but Fiesta's are just so good around 300whp that their isn't much of a market to reinvent the wheel.

*edit* i attached compressor map incase people wanted to reference it without having to google it.

We tuned my old g25-550 setup with 4 port aux and it made 308whp/280-ish wtq on 91 octane. Unfortunately with very small displacement we are just knock/detonation limited at that level. I think it made mid 20s for boost (like 25-26psi). I don't remember what the total timing was. That same setup with nothing more than changing to e85 fuel dyno'd at 390+whp multiple times and trapped 120-121mph in the 1/4 mile.

 

[Alkoran]

It blows my mind no one talks about the EFR 6258 and 6758.