SRM GT2860RS Boost curve

[MCP]

Figured I’d share this if anyone is wondering how something similar would perform. Finally finished 93 octane revisions, the enine is a 2.7 with 2.8 heads and cams and 82mm pistons. The turbos are SRM’s first gen Garrett turbos utilizing their China hot side housings with a TIAL waste gates. Build quality on them are meh but I’ve always liked the idea of having Garrett CHRA’s in a K04 sized housing that bolts up to stock manis. Will post E85 boost curves as well. Intercoolers on the car are SRMs newest gen. IMG_7460.jpg


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[LJS]

Nice flat boost curve
Could you post FAT's for both pump gas and E85....

[MCP]

Nice flat boost curve
Could you post FAT's for both pump gas and E85....

I’ll post my last logs when I get the chance.


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[MCP]

Didn’t realize you can’t post excel docs on here, do you guys just input an equation into excel that uses RPM to calculate the time for FATS?


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[LJS]

Looks like your graph was generated through ECUxplot---if YES then simply open the same file in the app, click on OPTIONS and select SHOW FATS WINDOW

[MCP]

IMG_7462.png

Tried organizing them by revision, but revision 10 is at the forefront of the bar graph. Revision 10 is slower because it was pulling a bit of timing. I was sent the last revision but I have not logged on it yet. There are two logs per revision, the quicker ones are on a negative slope and the slower ones are on a positive slope, the FATS on flat ground should be an average of the two.


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[MCP]

IMG_7463.jpg
One more graph comparing the last two revisions.


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[S4James]

why is it slow?

[Silverex]

So this is with their older rs6 turbine housings and not the new ones which have a larger A/R than rs6 correct?

Any 60-130 times?

why is it slow?

Does seem alil slow for 28psi and winter weather but it is running pretty low timing. From the results I’ve seen posted on just pump gas they never seem to do great…really need e85 to shine.

[MCP]

why is it slow?

LOL. To be completely honest I shared the same sentiment too. It’s about as quick on these turbos on the 93 octane file as it was on my old k04 e85 set up, so I used that to justify that it’s quick enough on pump. Was seeing if anyone else thought the same or if there are any areas where there is room for improvement.


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[MCP]

So this is with their older rs6 turbine housings and not the new ones which have a larger A/R than rs6 correct?

Any 60-130 times?



Does seem alil slow for 28psi and winter weather but it is running pretty low timing. From the results I’ve seen posted on just pump gas they never seem to do great…really need e85 to shine.

Wasn’t aware that their new housings were larger, but correct this is their old ones. No 60-130 times yet on pump, but plan on getting some tonight before I start the e85 tuning process.


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[S4James]

So this is with their older rs6 turbine housings and not the new ones which have a larger A/R than rs6 correct?

Any 60-130 times?



Does seem alil slow for 28psi and winter weather but it is running pretty low timing. From the results I’ve seen posted on just pump gas they never seem to do great…really need e85 to shine.

With meth i cracked 2.8 on 93 on straight k24s... On paper those turbos should be flowing a fuck lot more air. I agree the timing is really weak on this tune... More like what I would see for 91 octane. 93 should be able to take 15 degrees or so.

[CELison]

While tuning I was running 3.6 FATS on 93 and wastegate pressure…. JB RS6/K24

[MCP]

With meth i cracked 2.8 on 93 on straight k24s... On paper those turbos should be flowing a fuck lot more air. I agree the timing is really weak on this tune... More like what I would see for 91 octane. 93 should be able to take 15 degrees or so.

Yeah not sure why it’s not allowing for more timing to be honest. On the flow side of things the logs show 425 g/s which translates to about 28lbs/min per turbo so the compressor is flowing around 75ish% of what the theoretical max is. Even if you factor in exhaust housing, intake plumbing, small compressor housing, still probably not touching it’s absolute max potential. Will ask to see if boost can be bumped up on the e85 file.


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[RMode]

Yeah not sure why it’s not allowing for more timing to be honest. On the flow side of things the logs show 425 g/s which translates to about 28lbs/min per turbo so the compressor is flowing around 75ish% of what the theoretical max is. Even if you factor in exhaust housing, intake plumbing, small compressor housing, still probably not touching it’s absolute max potential. Will ask to see if boost can be bumped up on the e85 file.


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What inlet size are being used?

I wouldn’t get hung up on timing until you can sample a variety of fuels.

Any elevation?


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[MCP]

What inlet size are being used?

I wouldn’t get hung up on timing until you can sample a variety of fuels.

Any elevation?


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Typical RS4 sized inlets with a stock y pipe. No elevation.


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[MCP]

Last revision FATS times look about the same. Don’t know why the last two revisions were so much slower than revision 9, only thing I can think of is I noticed the fuel I filled the tank with for these past two runs was 93 octane without any ethanol content, but I doubt that’s why timing had to be pulled. Either way it’s what it does on e85 that I’m more so looking forward to seeing, I’ll update as I progress with that.

IMG_7480.png


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[Mocke]

https://www.garrettmotion.com/racing...7BWmEiYq24yXEE

Michael.
Why is it slow? For several reasons.
Not that Garretts compressor map is relevant here, but its easier to understand.
Have a look at the compressor map for GT2860rs.
Based on that, smallest A/R for these is 0.57 and you are running K04rs6? which is 0.42
And we dont even have to look at the compressor housing, which in garretts case is massive compared to k04s.

Running 1.9 - 1.8bar overpressure for such a big wheel in small housing is no bueno on petrol.
On top of its way too rich for pump petrol. The flame speed slows down.
This is dangerous if you start pushing it in high gears as those EGTs will skyrocket.

GL.

[MCP]

https://www.garrettmotion.com/racing...7BWmEiYq24yXEE

Michael.
Why is it slow? For several reasons.
Not that Garretts compressor map is relevant here, but its easier to understand.
Have a look at the compressor map for GT2860rs.
Based on that, smallest A/R for these is 0.57 and you are running K04rs6? which is 0.42
And we dont even have to look at the compressor housing, which in garretts case is massive compared to k04s.

Running 1.9 - 1.8bar overpressure for such a big wheel in small housing is no bueno on petrol.
On top of its way too rich for pump petrol. The flame speed slows down.
This is dangerous if you start pushing it in high gears as those EGTs will skyrocket.

GL.

Yeah, the effect or housing size is probably more than I let on for flow limitation and back pressure causing high temps, e85 May quell that temp a bit. Realistically on 93 octane I don’t even need it to be anything special/fast. I’m curious to see how they perform on E.


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[Steve Bassen]

I'm running the same turbos on my built 2.7T longblock, but we haven't had a chance to turn it up yet while putting together a new wideband package and 5 bar MAP setup and ironing out a few other minor things with the build. I can certainly say, though, that even with the mild boost it's running now (18psi tapering to 16) the difference between 93 pump and E85 (tested at 85%) without touching boost and just being able to throw assloads more timing at it was night and day; the cooling effect E85 has on a choked/"hot" setup like this is ridiculous.

[Tightmopedman9]

On top of its way too rich for pump petrol. The flame speed slows down.
GL.

You think an AFR of 11.6 is too rich for gasoline

[MCP]

Third revision, definitely feels happier on E. Running out of MAF up top with the 85mm unfortunately, so I don’t foresee much improvement from here on out in times.
IMG_7938.jpg
IMG_7937.jpg
IMG_7940.jpg
IMG_7939.jpg


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[Silverex]

Nice improvements switching to E85!

One thing that sticks out to me is how much your IATs rise. I’d be curious how a lower boost setting would affect that and power, they gotta be blowing a lot of hot air at that psi.

With that said I bet in colder weather it picks up a couple numbers.

[MCP]

Nice improvements switching to E85!

One thing that sticks out to me is how much your IATs rise. I’d be curious how a lower boost setting would affect that and power, they gotta be blowing a lot of hot air at that psi.

With that said I bet in colder weather it picks up a couple numbers.

Nice improvements switching to E85!

One thing that sticks out to me is how much your IATs rise. I’d be curious how a lower boost setting would affect that and power, they gotta be blowing a lot of hot air at that psi.

With that said I bet in colder weather it picks up a couple numbers.

Nice improvements switching to E85!

One thing that sticks out to me is how much your IATs rise. I’d be curious how a lower boost setting would affect that and power, they gotta be blowing a lot of hot air at that psi.

With that said I bet in colder weather it picks up a couple numbers.

Ran them at lower boost settings and it definitely didn’t pull the same way (backed by FATS). It definitely pulls much harder with the added boost. Coming from the 4.0t land, an increase of only 20 degrees F IAT on a pull would be impossible, so I’m ok with the delta here tbh. I’m also curious how it would perform in colder weather though, in theory should be able to pick up a bit of time.


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[Blazius]

30 PSi on 2860RS is quite insane, you will not get better temps for sure :)

If you want I have speed density solution for these cars so you can ditch the maf properly :)

[RMode]

What was ambient at to generate such a high IAT?


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[MCP]

What was ambient at to generate such a high IAT?


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It was around 80ish outside. Runs were back to back, so that’s why one of the pills starts at a slightly higher IAT


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[MCP]

30 PSi on 2860RS is quite insane, you will not get better temps for sure :)

If you want I have speed density solution for these cars so you can ditch the maf properly :)

30 psi on my intake set up and hot side is a lot I will admit. Purely flow wise I’m around 80% of what the compressor wheels are capable of, but with the above stated restrictions I’m probably at the limits. Is speed density similar to the blow through HPX?


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[MCP]

What FATS do people typically see on similar sized RS6 sized turbos under similar conditions?


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[Silverex]

Coming from the 4.0t land, an increase of only 20 degrees F IAT on a pull would be impossible, so I’m ok with the delta here tbh. I’m also curious how it would perform in colder weather though, in theory should be able to pick up a bit of time.

I run the same SMICs and I normally see 10-15degree rise. The ECU pulls timing over a 100 and was wondering if that would offset the boost. If you have any logs of the earlier e85 maps on lower boost it’d be cool to see them.

speed density similar to the blow through HPX?

SD=No maf

Most rs6 hybrids on corn see about 2.3-2.5s fats.

[s4rmm]

Most rs6 hybrids on corn see about 2.3-2.5s fats.

Haven't seen many logs posted with 2.3s

[MCP]

I run the same SMICs and I normally see 10-15degree rise. The ECU pulls timing over a 100 and was wondering if that would offset the boost. If you have any logs of the earlier e85 maps on lower boost it’d be cool to see them.



SD=No maf

Most rs6 hybrids on corn see about 2.3-2.5s fats.

I run the same SMICs and I normally see 10-15degree rise. The ECU pulls timing over a 100 and was wondering if that would offset the boost. If you have any logs of the earlier e85 maps on lower boost it’d be cool to see them.



SD=No maf

Most rs6 hybrids on corn see about 2.3-2.5s fats.

The lowest temp rise I saw was in the low teens, I will see if I can dig one up, I think I only have a log from when it was on gate pressure (~18-19psi). Had no idea that the temp threshold for pulling timing was 100 degrees, would’ve thought it’d be a bit higher.


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[Blazius]

30 psi on my intake set up and hot side is a lot I will admit. Purely flow wise I’m around 80% of what the compressor wheels are capable of, but with the above stated restrictions I’m probably at the limits. Is speed density similar to the blow through HPX?


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Speed density meaning the car would run from a MAP in the intake/ from the intake(there are hose connection sensors) This is how I run my car.
BE AWARE that removing the MAF and running the car like that is not speed density like most people "do" it, its just TB % opening with RPM with some corrections, its basically limp mode.

[MCP]

Speed density meaning the car would run from a MAP in the intake/ from the intake(there are hose connection sensors) This is how I run my car.
BE AWARE that removing the MAF and running the car like that is not speed density like most people "do" it, its just TB % opening with RPM with some corrections, its basically limp mode.

Do you need a special MAP to run it, or do you mean just off of the stock MAP and throttle %?


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[Blazius]

Do you need a special MAP to run it, or do you mean just off of the stock MAP and throttle %?


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I wrote code the make the car run off a MAP , like newer VAG engines do like the 2.5 TFSI etc. The sensor can be any really as long as I can come up with a scaling for it but it needs to be able to read a decent amount of vacuum.
I am currently using a Ford sensor (with hose connection so modification was necessary to the intake except a hose connection)which I would recommend because the working range is 0.2bar-3bar. for 2 bar of boost. If you require more than that there are sensors which read up to 4 bar ofcourse.

The stock MAP is a boost sensor really not a MAP, its only used for boost control and nothing else. People think "maffless" is equalivent to speed density on this ecus but its not its limp mode. If bosch wouldnt have made the ecu like that the car wouldnt run.. but ofcourse backups are needed :)