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Hello turbokittys, hope I posted in the right section, here goes: ...
Is anyone running a 0.49 A/R turbine housing on their T25/T28 turbocharged 1.8 engines? I'm curios if it would be to restrictive in high RPMs... Got a GT2871 laggy choochoo boy on my 1.8 vvt, makes 1 bar of boost at about 4K and I'm looking for ways to improve that. I think I've finally found a seller willing to sell me just the turbine housing, most of them chinacharger sellers refused. I'm curious if others have tried such a small turbine housing? If someone wants to share some knowledge on the subject, I'm willing to listen, well, read... 😊
My setup for now:
1.8VVT, h-beam rods, everything else stock inside the engine. taco-taco manifold (bought a kraken manifold about a month a go, just waiting to be fitted), chinese so called GT2871, cold side: a/r 0.60, inlet 3", outlet 2", inducer 54.13mm, exducer 70.00mm, hot side: a/r 0.64, inducer 65.00mm, exducer 56.00mm. kraken 3'' exhaust, 550cc injectors, electronic boost control, 5 speed with 4.1 final drive.
And if you're wondering why i use cheap chinese parts, it's because it's cheap fun and it seems like a good learning path, especially for the mapping part, if i break something, it's not that big of a loss. I've built my turbo setup for about 1000 euros (1100usd), ecu, wbo2 and cops not included, had those from my previous ITB setup...
the power drop at 5800 is due to my AFR going down to 10, EGT based fuel enrichment, will sort that out when it will be less riskier (less police) to go out for drives... s
PS
I know my breather setup is ****, thanks to some good writeups on that subject, i can sort that out to...
What is your EGT enrichment strategy that is causing AFR going down to 10? Directionally a smaller A/R housing is going to make it worse.
Secondly, I assume your ~4000rpm 1 bar of boost is in 3rd gear? Maybe that's not so bad. With a genuine Garrett GTX2860 and 0.64 housing and a twin port actuator my car in 3rd (6 speed, 3.6, ie ~10% shorter 3rd gear than yours) was hitting 200kpa around 3400rpm, and that's still at 100% duty. Would probably be more like 3500-3600rpm if the boost target was 200kpa, and add another ~150rpm for a single port actuator. This translated to a 1:1 (still with 3.6) pull to make 200kpa around 2850rpm, which seems good.
Have you done a 1:1 pull from 2k rpm at WOT and 100% WG duty (or wired shut) until it hits boost creep?
10% enrichment at 1650F, I reduced it to just 2% now, when there will be less police on the streets i'll do some more testing and adjustment, this f*ckin lockdown...
Yes, 1bar at 4k rpm is in 3rd gear. I understand that from a tuning point of view it makes more sense to use the 4th, 1:1 ratio, because it puts more load on the engine and it spends longer times through the cells, but i live in a valley between the mountains, this is where I do most of my street tuning and there aren't to many long, straight roads where I can safely do 4th gear pulls. Also from a driving point of view 3rd gear pulls feel closer to real driving expirience, maybe my perspective on this subject is wrong...
This is a 4th gear pull, but not with 100% DC upto target
I've used 1650F turbine inlet temperature as my calibration limit with EGT enrichment with mine, though I have been thinking of going the other way to a 0.86 A/R because on a big track, eg Silverstone, the EGT limit is an issue. I'm still not sure if 1650F/900C could be exceeded on a stock VVT head, but that's another topic. I'd be really tempted by a 0.75 A/R hotside or so though if it was available since on track at least, I could live with slower boost response.
Is your car only a street car or on track too? Perhaps a smaller turbo in general might get you the response you are after, eg a GT2560. The easiest way to check the response of your turbo setup would be to set your overboost protection and lockwire the WG closed.
I would like to see some G25 0.49 T25 data on a miata though. I don't really understand the point of a 550hp turbo with such a small hotside, unless there's something different in the way it flows. It must make sense somewhere, but I don't see the numbers being comparable to any of the older turbos. It almost looks like it flows axially and the WG looks very effective, so perhaps the 0.49 gives the turbo and early spool, but the WG efficiency stops the backpressure from rising at high revs. I would be really interested to see data on this.
You should definitely set your boost cut before trying it.
I used to have one of those Chinese 2870s (didn't actually measure as a 71mm compressor). My spool data is listed in the "I want your spool data" thread. Maybe there's data points from others with a housing like the one you are planning to use.
I would only be concerned that the curvature of the turbine wheel between the inducer and exducer could be proprietary to each Chinese manufacturer or even to each trim of turbine wheel from the same manufacturer. I've messed with a few and they aren't always the same.
As for reducing your top end power, it might or may not at the level you are running. You will have to try it or find the data of others in the spool thread or elsewhere. An EBC helps.
From experience, EGTs getting too high caused my wastegate flapper arm to bend and bind up. Get that under control first. Make sure it moves freely and closes completely.
I've used 1650F turbine inlet temperature as my calibration limit with EGT enrichment with mine, though I have been thinking of going the other way to a 0.86 A/R because on a big track, eg Silverstone, the EGT limit is an issue. I'm still not sure if 1650F/900C could be exceeded on a stock VVT head, but that's another topic. I'd be really tempted by a 0.75 A/R hotside or so though if it was available since on track at least, I could live with slower boost response.
Is your car only a street car or on track too? Perhaps a smaller turbo in general might get you the response you are after, eg a GT2560. The easiest way to check the response of your turbo setup would be to set your overboost protection and lockwire the WG closed.
I would like to see some G25 0.49 T25 data on a miata though. I don't really understand the point of a 550hp turbo with such a small hotside, unless there's something different in the way it flows. It must make sense somewhere, but I don't see the numbers being comparable to any of the older turbos. It almost looks like it flows axially and the WG looks very effective, so perhaps the 0.49 gives the turbo and early spool, but the WG efficiency stops the backpressure from rising at high revs. I would be really interested to see data on this.
Brainstorming : you could run lower boost and a bit more timing on the long tracks or EGT/MAP triggered water meth injection... or contact Skuzzle Motorsport or Valley 5s, from what i've seen they are very good in mapping and prepping track and also street miatas.
My 5 is inteded to be a dual duty, but it didn't see any track time since I turbocharged it. Before the lockdown I used to beat the snot out of it once/twice a week, up the mountain, at 14.5 psi with the intention to run about 12-12.5 at the track, main reason was to see what fails first and address the issues before it gets on the track, failing at the track is expensive, failing near home, not so much , also I'd hate to waste time and money for not going prepared...
Originally Posted by sixshooter
You should definitely set your boost cut before trying it.
I used to have one of those Chinese 2870s (didn't actually measure as a 71mm compressor). My spool data is listed in the "I want your spool data" thread. Maybe there's data points from others with a housing like the one you are planning to use.
I would only be concerned that the curvature of the turbine wheel between the inducer and exducer could be proprietary to each Chinese manufacturer or even to each trim of turbine wheel from the same manufacturer. I've messed with a few and they aren't always the same.
As for reducing your top end power, it might or may not at the level you are running. You will have to try it or find the data of others in the spool thread or elsewhere. An EBC helps.
From experience, EGTs getting too high caused my wastegate flapper arm to bend and bind up. Get that under control first. Make sure it moves freely and closes completely.
I only found your GTX2867R spool data, which seems oddly laggy, but i asume it's because of the .86 housing. No spool data for a .49 housing whatsoever... buuuut, I've placed the order for it, should be here in about two weeks, so we'll see how it goes, if this won't get me satisfaction, it'll be the end of my chinacharger experimentation and will probably get a genuine GT2560R.
Well, this little covid spec turd arrived today, surprisingly a lot faster than all the gaskets I'm still waiting for to arrive from Europe, not f*ckin China...
Well, at least I can port the wastegate hole until the rest of the bits arrive...
@forum moderator, please change thread title to: "Chinacharger GT2870 A/R 0.49 Covid Spec experiment" 🤣
Well, experimenting is postponed for about 5 months, got a contract outside the country so won't be having as much play time as before. Dropped a new, old 5 speed, and off to work... 😆
04-27-2020, 05:02 AM
Chinacharger GT2870 A/R 0.49 Covid spec experiment
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: you could run lower boost and a bit more timing on the long tracks or EGT/MAP triggered water meth injection... or contact Skuzzle Motorsport or Valley 5s, from what i've seen they are very good in mapping and prepping track and also street miatas.
, also I'd hate to waste time and money for not going prepared...
