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First things first, I am no where near as knowledgeable as everyone posting here. I also know that this doesn't make 500hp...

BUT wouldn't the "87S72 (AirWerks S300SX-E) 13009097006 13009097047" be a much better fit? From what I see it would give you a much more broad power band over a much larger RPM range? Don't get me wrong, 500hp definitely has Big D Energy, but if you only make power between 5k-7k rpm then you might as well make a kswap drag car. But if you are looking to keep the MR2 as a canyon carver like it is designed for. Wouldn't this be a better option?
Why would you get a 800+ HP turbo to run at 500 HP or less?


I think a 2GR-FE turbo setup could be lots of fun, but just because you're putting a turbo on the engine, there's no need to shoot for double+ the NA HP. This isn't a lower powered 4 banger, so you can go with more an OEM+ turbo sizing and it'll have strong response above ~2.5k RPM to redline.
 

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If you are looking to make it a canyon carver, leave the 2GR NA, it's perfect as it is.
Really what I meant is that it could go around a turn and power out of it without being at redline the whole time. Any road course, autocross, daily driving would be better suited with a turbo like that vs the other ones posted wouldn't it?

Since that part number doesn't have the hotside included, what would anyone with it?

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Sorry, I am referring to the drop down in the compressor maps calculator. I would post a link but apparently you can't post a link with your first post on the forum. Been a member for a long time, just always used it as research instead of actively posting.
 

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Really what I meant is that it could go around a turn and power out of it without being at redline the whole time. Any road course, autocross, daily driving would be better suited with a turbo like that vs the other ones posted wouldn't it?
Sure a smaller turbo is going to provide better response than a bigger one, all else equal, so if you must have a turbo that's probably the way to go. I just feel that for the usage you have described, my preference is to leave it NA.
 

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Sure a smaller turbo is going to provide better response than a bigger one, all else equal, so if you must have a turbo that's probably the way to go. I just feel that for the usage you have described, my preference is to leave it NA.
If you want much more than ~300 rwhp, turbo sounds like the next logical step on a 2GR-FE. If you want ~280-300 rwhp, NA is obviously the way to go.


A more modern turbo that's also properly sized than most MR2 guys are used to using will make a pretty responsive setup turbo setup overall.
 

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If you want much more than ~300 rwhp, turbo sounds like the next logical step on a 2GR-FE. If you want ~280-300 rwhp, NA is obviously the way to go.


A more modern turbo that's also properly sized than most MR2 guys are used to using will make a pretty responsive setup turbo setup overall.
Agreed. And if you want say, 450hp max, then a moderately sized turbo at relatively low boost (like you said, an OEM-like setup) would probably be very responsive and almost seamless to drive, since you are only adding +50% power with the turbo, instead of trying to double or triple the NA output like you would be with a big turbo on a small motor.
 

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Agreed. And if you want say, 450hp max, then a moderately sized turbo at relatively low boost (like you said, an OEM-like setup) would probably be very responsive and almost seamless to drive, since you are only adding +50% power with the turbo, instead of trying to double or triple the NA output like you would be with a big turbo on a small motor.
Almost like if someone moved a moderately sized turbo for a 3S-GTE... like say an EFR 6758... and then put it on a 2GR-FE as a single turbo.

Hmmmm....

*possible foreshadowing intensifies*
 

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If you're going to a small turbocharger to reduce lag, we should consider the max power we can run with a supercharger because that should keep the smooth power delivery of NA. Turbochargers are cool but are a lot of components to install
 

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Discussion Starter · #48 · (Edited)
I know that everyone prefers a speculative answer that they pull straight out of.... the air, but I'm gonna be obstinate here in sticking to an analytical answer to the question that is based on the modeling tools that we have available.

Let's take the EFR6758 and use matchbot.

Step 1. (see attachment 1)
First we start with the general inputs. Just for kicks we say we want to run at 10psi of boost so we enter that number versus rpm. We also enter the VE versus rpm (this comes from the NA torque curve).

Step 2. (see attachment 2)
We select a compressor from the compressor match curve, by using the drop down.

Step 3.
We eyeball the compressor curve and enter the compressor efficiency numbers back into the general inputs in attachment 1.

Step 4. (see attachment 3)
We line up the operating points with the choice of wheel and a/r, by using the + and - buttons for the "Turbine Expansion Ratio." This is a crucial step as it changes the "Caculated Percentage of Wastegating." The higher this number the less the lag and the quicker the spool-up. Note we've chosen a 58mm wheel with a 0.80 a/r but you can choose anything you want.

Step 5.
We repeat steps 3 and 4 until the numbers converge which usually happens in just one iteration.

Step 6. (see attachment 4)
This gives calculated outputs, including HP and torque versus RPM. At this point, we can go back to Step 1 and change any of the inputs like for example the target boost versus rpm and see how this affects the output.

So overall this is a quick and easy (and cheap!) alternative to building x number of turbos and putting each one on the dyno to measure its performance - but whether this is good for you depends on whether you believe in engineering modeling or not. Maybe you prefer to just pull numbers out of... the air.

PS> As a bonus, I've added attachment 5, the calculated Torque and Hp versus RPM.
 

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If you're going to a small turbocharger to reduce lag, we should consider the max power we can run with a supercharger because that should keep the smooth power delivery of NA. Turbochargers are cool but are a lot of components to install
SCs are tough because they still take up a decent amount of space, and you generally have to work the engine pretty hard to get the same HP as a turbo setup. That crank drag is rough...

Plus most SC kits tend to use too small SCs to keep the cost down, so they're already handicapped on power output from the getgo and it's really expensive/difficult to change SC size on most kits.


I know that everyone prefers a speculative answer that they pull straight out of.... the air, but I'm gonna be obstinate here in sticking to an analytical answer to the question that is based on the modeling tools that we have available.

Let's take the EFR6758 and use matchbot.

Step 1. (see attachment 1)
First we start with the general inputs. Just for kicks we say we want to run at 10psi of boost so we enter that number versus rpm. We also enter the VE versus rpm (this comes from the NA torque curve).

Step 2. (see attachment 2)
We select a compressor from the compressor match curve, by using the drop down.

Step 3.
We eyeball the compressor curve and enter the compressor efficiency numbers back into the general inputs in attachment 1.

Step 4. (see attachment 3)
We line up the operating points with the choice of wheel and a/r, by using the + and - buttons for the "Turbine Expansion Ratio." This is a crucial step as it changes the "Caculated Percentage of Wastegating." The higher this number the less the lag and the quicker the spool-up. Note we've chosen a 58mm wheel with a 0.80 a/r but you can choose anything you want.

Step 5.
We repeat steps 3 and 4 until the numbers converge which usually happens in just one iteration.

Step 6. (see attachment 4)
This gives calculated outputs, including HP and torque versus RPM. At this point, we can go back to Step 1 and change any of the inputs like for example the target boost versus rpm and see how this affects the output.

So overall this is a quick and easy (and cheap!) alternative to building x number of turbos and putting each one on the dyno to measure its performance - but whether this is good for you depends on whether you believe in engineering modeling or not. Maybe you prefer to just pull numbers out of... the air.

PS> As a bonus, I've added attachment 5, the calculated Torque and Hp versus RPM.

Yep, that's pretty close to what I got on my numbers.

For a good real world comparison, an N55B30 BMW engine (3.0L I6, valvetronic (dual cam phasers + infinitely adjustable intake cam lift) uses a Borg Warner turbo very similar to the EFR lineup, but using Inconel turbine wheels and journal bearings. The CNC machined compressor wheel is 62 mm in major diameter and 45.8 mm inducer, with a smaller inducer than the EFR6258. The turbine wheel is 53 mm inducer, and a small 46.1 mm exducer.


EFR 6758 has a compressor inducer 53.8 mm, exducer of 67 mm of course. Turbine inducer of 58 mm (can't find turbine exducer diameter, but it's way bigger than 46.1 mm).

While the N55 has direct injection, I'd say it's pretty comparable to the 2GR-FE in power output at probably ~15% more boost (on the N55).

Here's a stock N55 setup with the turbo pushed pretty hard with a piggyback. I think most people shoot for 12-14 psi in the midrange, and the boost will bleed off up high due to the tiny compressor wheel:



Given the EFR6758 is 8 mm larger on the compressor inducer, 5 mm larger on compressor exducer, and 5 mm larger on turbine inducer (and probably at least 5 mm larger on turbine exducer), I'd say it should easily push out 440-450 rwhp on a 2GR assuming knock is kept in check. I've personally seen 450 rwhp out of an EFR 6758 on a smaller engine, but of course the larger 2GR is going to see lower compressor efficiency since the compressor wheel is being asked to flow a lot more at a lower pressure ratio. That said, you heat the air up less compressing it to a lower pressure, so that does alleviate some issues with compressor efficiency dropping up high.

Ultimately, if I was choosing an OEM+ turbo for a 2GR from scratch, I'd probably pick an EFR 7163, as the bigger compressor and turbine wheel should match up better with it. But it's a solid $150-200ish more expensive than the EFR 6758 (which is why I went 6758 this time around). An EFR 7670 is probably a good "medium sized" turbo for a 2GR IMO. It'll still fall off the compressor map towards redline for a pump gas setup, but it should still be pretty responsive.

Bigger than that and you'll start feeling the lag a bit more IMO.
 

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wakening and old thread...looking for a budget turbo build currently. I know BW has some that are under 1k but i'm not opposed to even a VSR or eBay turbo.

I've seen a ebay turbo with a 67mm turbine, 82mm compressor with a .82A/R make 425whp on a J35 honda at only 8psi.Something along that size sounds like a good start for me right?

If i could start off making 400whp from less than 8psi and over time as I work out perceived fueling issues and continue to increase the boost until either the trans gives up or the engine does. I'd like to start off with 400whp but have it not limit me there. I'm having my transmission "bulletproofed" so I'm willing to see how more much it can take. My torque convertor has a flash stall of 4000rpm, so having too responsive of a turbo might not let me hold the engine back with only the brakes. I haven't found a transbrake kit yet so that's not an option. My current exhaust is 2.25 dual with an X-pipe but once I turbo, I'll probably have a 3.5 single back exhaust to all for less back pressure.

what A/R size should i be looking at for the 2GRFE?
 

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G25 is too small all around for a 3.5L engine. I’m sure Garrett’s published displacement range backs that up.

You’d want at least a G30 frame for a 3.5L, maybe even G35.

Keep in mind a 550 HP capable small compressor at say 2.5 bar is not going to flow anywhere near 550 HP at 0.6 bar, and the efficiency will likely be pretty horrible past 30-35 lbs/min down there.
 

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G25 is too small all around for a 3.5L engine. I’m sure Garrett’s published displacement range backs that up.

You’d want at least a G30 frame for a 3.5L, maybe even G35.

Keep in mind a 550 HP capable small compressor at say 2.5 bar is not going to flow anywhere near 550 HP at 0.6 bar, and the efficiency will likely be pretty horrible past 30-35 lbs/min down there.
G25 maybe if doing twins. Even a G30 is small imo.

I'm looking for a single turbo setup. I have easy access to E85 but will run premium in a pinch and lower the boost.

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I feel Garrett’s G series is going even more lopsided on turbine vs compressor size. Garrett’s historically under turbined their popular sizes, which works for small displacement engines at really high boost pressures, but for larger displacement engines running at low boost something like a big BW EFR or Airwerks turbo fits the engine better.
 

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Discussion Starter · #55 ·
I've seen a ebay turbo with a 67mm turbine, 82mm compressor with a .82A/R make 425whp on a J35 honda at only 8psi.Something along that size sounds like a good start for me right?
If you're asking specifically for a good value on a turbo with 67mm turbine, 82mm compressor I would point you at this:

Available options for a/r with T3 inlet are 0.62, 0.83, 1.06. The Pulsar turbos seem to be well-made and durable. I've seen them used in some builds without any issue.

These turbine and compressor sizes fall in between the gaps of the BW line-up (see here), otherwise I would run a Matchbot analysis for you based on those sizes.

Given how the volumetric efficiency seems to drop from 6000RPM onward, I would maybe go with the 1.06 a/r to try to get more flow in at higher rpm. Definitely I would not go with 0.62 - that would make it fall on its face even worse.
 

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If you're asking specifically for a good value on a turbo with 67mm turbine, 82mm compressor I would point you at this:

Available options for a/r with T3 inlet are 0.62, 0.83, 1.06. The Pulsar turbos seem to be well-made and durable. I've seen them used in some builds without any issue.

These turbine and compressor sizes fall in between the gaps of the BW line-up (see here), otherwise I would run a Matchbot analysis for you based on those sizes.

Given how the volumetric efficiency seems to drop from 6000RPM onward, I would maybe go with the 1.06 a/r to try to get more flow in at higher rpm. Definitely I would not go with 0.62 - that would make it fall on its face even worse.
Thanks! I'll look at those.

Considering that junkyard J35 made all 8 psi by 2500 rpm on the .82 A/R with a hacked up "turbo kit", a 1.06 A/R would hopefully slow the " all the boost-all at once" by at least 500 rpm or more.

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Discussion Starter · #57 ·
While playing around with the models I asked the question "what if you could control the boost and ramp it with rpm?" The objective would be to make a nice flat torque curve. Here's what I came up with using the EFR 8474, 84mm compressor with a 74mm turbine.
BorgWarner MatchBot

In summary this looks like this:
73480


All the points of the operating range fall inside the compressor map - even if just barely.

73481



The calculated wastegating percentages do not seem too unreasonable - the wastegate starts to open between 2000 and 3000 rpm.

73482


If this were do-able it would almost certainly have to run either water-methanol injection or e85 to maintain some spark at the higher boost, otherwise it would just.... fall on its face.
 

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If you can get rpm, MAP, and accelerator pedal position, it would be easy to devise wastegate control logic, though I doubt the torque curve would look like that if the boost pressure were as described. You would probably start ramping it up around 5000rpm if you wanted to maintain flat torque.
 

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Bumping this up - what is everybody's thought with a 2GR-FE on fitting a reasonably sized turbo over the transmission? I've been trying to eye clearance from pics posted and using my own engine bay as a reference, and it looks MAYBE feasible to fit a "large" turbo there.

Thoughts on fitting it over the E153:
1. Use cheap RWD 2GR headers + 2.25" crossover pipe to a divided T4 flange
2. T4 flange is as low as possible, somewhere between the TB inlet and the back side of the E153.
3. Something like this using Alex W's car and my awesome paint skills. Borg Warner S362 shown because it was the only one I could find even close to perspective
74680


The turbo isn't exactly scaled correctly due to perspective, or even rotated correctly, but the compressor housing is about 8.5", turbine housing about 7" in diameter from what I can tell, and about 9.5" long from compressor inlet to v-band.

5. Exhaust would make a quick dive down under TB area, cram a cat on it somewhere close to the firewall, then connect up to the Berk muffler.
6. Single ~45 mm ext. wastegate with a divider welded in, recirculated after the cat.

Now onto selection - how does it flow?

S362 SXE, aka 6268 aka 8376, 10 psi, 500 BHP:

74681


Compressor efficiency stays high, reaching 67% right at 7200 RPM and 10 psi.


Other option is slightly smaller S257 SXE, 10 psi, 470 BHP, compressor efficiency drops to ~58-56% at 7200 RPM. I also chopped off 5% on the S257 SXE engine VE above 5000 RPM, as the intake/exhaust pressure ratio started getting fairly unfavorable (~20 psi ebp vs. 10 psi intake MAP), so I couldn't see the VE curve holding with this turbo like the S362SXE likely would.

S257SXE
74682


The compressor housing is ~7" in diameter, turbine ~6.5-7" diameter, turbo is ~9" long, so packaging does get a little easier, mainly that it's a hair shorter, and the compressor housing is at least 1.5" in diameter. This looks like a nice street turbo, but I do worry if I'm being optimistic with how it'll perform on the top end. It is a tiny bit small for a 3.5L, but would fit something like a 3L with a 2GR-FE's VE curve very well.


As for why not an NA 2GR-FE - I totally see the appeal, but I don't think I'd be satisfied with the power and "theater" of the car in the long run. I keep looking at my EFR 6758 and thinking maybe running it for a bit, but I think a 2GR would really fall on its face after 5k RPM with a turbo that small, and I ultimately think I'd be wasting time even fabricating stuff up to make it work.

Thoughts? Measurements and pics maybe??? :)
 
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