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Determining my Stage 2 WRX speed by comparing to other cars

1293 Views 66 Replies 9 Participants Last post by  silver_scooby, 
EnsRealissimum
I recently took my '21 wrx to stage 2: GS Intake, ETS Jpipe, AWE Touring Catback, and a pro-tune. Mustang dynos says I'm 301 whp and 280 tq, and I was told it's about 371 at the crank (about 100hp up from stock).

I am trying to know what kind of 0-60 or 1/4 mile my car would get assuming it was launched well.

I was comparing it to an audi S5 to start. The audi is 354 crank HP, AWD and weights about 600lbs more at 3900lbs. Car and driver says the S5 does about a 4.3s 0-60 and a 12.9s 1/4 mile.

Would it be reasonable to assume, that if launched well, my car would do it a bit faster since it is more hp and lower weight?

I'm unsure how many other factors are involved like gearing and transmission, etc. Any thoughts would be great. It's not super important, I just like to think about these things and am curious how I'd match up.
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zax
silver_scooby said:
Why do they need to be tuned richer? I can't think of any reason boxer layout would need to run richer than say an i4 or v6. Is it just inadequate or late response from sensors?
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A cacophony of reasons I'm sure, but mostly we just know this from experience. Subaru's engine's (particularly the EJ) need to run a good 0.1 Lambda richer to stave off detonation. MOST of the contributing factors don't have anything to do with the cylinder layout... except one: boxer engines do not typically have a very long stroke and the rod ratios are larger which means the TDC dwell times are longer. In addition to the shorter stroke, the valves are usually larger reducing intake port velocity which also reduces fuel mixing in the cylinders. All of this means that EJs are a bit more prone to detonation and require more fuel to reduce charge temps and run happy.

Once you know this, it's pretty obvious why Subaru chose to design the FA differently - longer stroke, lower rod ratio, direct injection, and smaller valves/high velocity ports improve cylinder mixing. Piston oil squirters probably would have also helped. Subaru hasn't used oil squirters since the EJ20G in the 90s. It's a bit head-scratching why they continue to omit these. I suppose they have deemed the notch on the rod big-end sufficient for lubrication and cooling.

The RA thing is definitely ironic. I can see hot pistons causing a nox problem but it shouldn't cause a HC problem. Far as I know, the only way to get oil jets is an HKS shortblock. IAG and outfront don't have oil jets listed on their site.
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Correct. The heat issue was more about the NOx emissions. I feel that Subaru should have engineered oil squirters into the block. It's a curious omission. The G16E-GTS in the GR Yaris/Corolla has 9 piston oil squirters - 3 for each cylinder!
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silver_scooby said:
The DCT's primary advantage comes from a violent launch. Stock for stock, the CLA45 is about 1.4sec faster in 1/4 mile. Add 100hp/~30% to the wrx and that advantage evaporates.
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I can't totally disagree. The launch was violent in the CLA. It was every time, too. I was serious that playing tag with my better half was a near thing. The CLA was every time. 300 pound feet more and 275 additional horses were mitigated by that every time thing. The DCT was a whole bunch faster than I ever have been in shifting.
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silver_scooby
zax said:
A cacophony of reasons I'm sure, but mostly we just know this from experience. Subaru's engine's (particularly the EJ) need to run a good 0.1 Lambda richer to stave off detonation. MOST of the contributing factors don't have anything to do with the cylinder layout... except one: boxer engines do not typically have a very long stroke and the rod ratios are larger which means the TDC dwell times are longer. In addition to the shorter stroke, the valves are usually larger reducing intake port velocity which also reduces fuel mixing in the cylinders. All of this means that EJs are a bit more prone to detonation and require more fuel to reduce charge temps and run happy.

Once you know this, it's pretty obvious why Subaru chose to design the FA differently - longer stroke, lower rod ratio, direct injection, and smaller valves/high velocity ports improve cylinder mixing. Piston oil squirters probably would have also helped. Subaru hasn't used oil squirters since the EJ20G in the 90s. It's a bit head-scratching why they continue to omit these. I suppose they have deemed the notch on the rod big-end sufficient for lubrication and cooling.



Correct. The heat issue was more about the NOx emissions. I feel that Subaru should have engineered oil squirters into the block. It's a curious omission. The G16E-GTS in the GR Yaris/Corolla has 9 piston oil squirters - 3 for each cylinder!
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Very interesting. I didn't know the EJ had these tuning issues. I also remember Subaru played up the piston crowns on fa20 as being particularly good for mixing when they introduced it.

Between all of that, I guess the fa20 should be easier on the cats. Anecdotally, I logged the AFR on mine and it stayed around 14.7. Rarely dropped to 14.6 or lower and sometimes went above.

Hopefully that means cobb or someone else can figure out a workable cat. Let's see what OP finds over the next few months.
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silver_scooby
Camaromjr said:
I can't totally disagree. The launch was violent in the CLA. It was every time, too. I was serious that playing tag with my better half was a near thing. The CLA was every time. 300 pound feet more and 275 additional horses were mitigated by that every time thing. The DCT was a whole bunch faster than I ever have been in shifting.
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What exactly are you talking about here? And whatever that other car might be, the numbers don't mean much without weight, transmission and driveline details.

A "500hp" gt3 runs a 10.8s quarter while an 800hp redeye takes 11.8s.
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zax
silver_scooby said:
Anecdotally, I logged the AFR on mine and it stayed around 14.7. Rarely dropped to 14.6 or lower and sometimes went above.
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I'm assuming you are talking about cruise. Of course the EJ will cruise at 14.7-15.0:1 like any other standard engine. No Subaru that I'm aware of is designed for lean-burn (which sharply increases NOx if not properly designed).

I was talking about WOT which is still a consideration for emissions compliance as far as I'm aware.
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XJman
silver_scooby said:
Very interesting. I didn't know the EJ had these tuning issues. I also remember Subaru played up the piston crowns on fa20 as being particularly good for mixing when they introduced it.

Between all of that, I guess the fa20 should be easier on the cats. Anecdotally, I logged the AFR on mine and it stayed around 14.7. Rarely dropped to 14.6 or lower and sometimes went above.

Hopefully that means cobb or someone else can figure out a workable cat. Let's see what OP finds over the next few months.
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That's about normal for no boost load. You'll see afr numbers more inline with N/A vehicles when not under positive manifold pressures.

When you hammer down you should see it drop, and if I recall, level out somewhere in the 10.5-11 range.
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silver_scooby
zax said:
I'm assuming you are talking about cruise. Of course the EJ will cruise at 14.7-15.0:1 like any other standard engine. No Subaru that I'm aware of is designed for lean-burn (which sharply increases NOx if not properly designed).

I was talking about WOT which is still a consideration for emissions compliance as far as I'm aware.
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XJman said:
That's about normal for no boost load. You'll see afr numbers more inline with N/A vehicles when not under positive manifold pressures.

When you hammer down you should see it drop, and if I recall, level out somewhere in the 10.5-11 range.
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Yeah it was an OBD2 display without storage. So basically looked at the screen when I could which was part throttle steady speed most of the time.
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silver_scooby said:
What exactly are you talking about here? And whatever that other car might be, the numbers don't mean much without weight, transmission and driveline details.

A "500hp" gt3 runs a 10.8s quarter while an 800hp redeye takes 11.8s.
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There are 3 cars, kinda blended together. The 6th Gen 2016 Camaro SS (455HP / 455 pound feet - 3,650 pounds) with the TR6060 transmission had the NLS. I took it to Beech Bend Speedway in 2017. I couldn't break 13 seconds. No idea what the DA was. My best time at NOLA Motorsports was 2:04. In 2018, my better half bought a CLA45 (375HP/350 pound feet - XF went back off lease) A bit later in 2018 bought a 2018 Camaro ZL1 with the 10L90 transmission (650HP/650 pound feet - 3,875 pounds). In 2019 at Beech Bend, I turned 11.88 at 129MPH. I turned 1:58.9 at NOLA Motorsports.

In playing tag with my better-half, in either the SS or the ZL1, the lil' 4 pot was a handful. It launched like a beast. The road conditions were nearly irrelevant. It would hook and pull straight up. The SS was a bit tricky to launch. The ZL1 demanded respect and a careful application of the right foot. Launch control launches in the ZL1 were never as violent as the launches in the CLA45. The 4 pot usually garnered more lookers than the other 2 at Cars&Coffee. All three cars were white.
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silver_scooby
Hmm. Part of the difference is both the camaro and zl1 are rwd. CLA45 is awd.
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silver_scooby said:
Hmm. Part of the difference is both the camaro and zl1 are rwd. CLA45 is awd.
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Yes, the AWD was and is a big deal. The launch control was better, too. IMHO, the 10L90 shifted faster than the DCT. The 10L90 (10 forward gear ratios / rated up to 900 pound feet) was benchmarked against the Porsche PDK. I never tracked the CLA. I never took it to the strip. The CLA was track warrantied. The SS and ZL1 were both warrantied for track / strip use, as well.
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EnsRealissimum
Oi, XJman. I think i saw you in another thread say that built blocks have to be rebuilt every 15k or so. I have no idea where I saw it so I wanted to ask if you recall it and what you meant by that. It's possible it was from years ago.
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zax
EnsRealissimum said:
Oi, XJman. I think i saw you in another thread say that built blocks have to be rebuilt every 15k or so. I have no idea where I saw it so I wanted to ask if you recall it and what you meant by that. It's possible it was from years ago.
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15,000 miles is a bit on the low side, but they certainly don't last as long as an OEM block. Depending on the materials used of course.

A 2618 piston in an iron-lined cylinder, you are looking at 50,000-75,000 miles lifespan assuming it was built by a reputable manufacturer.
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XJman
EnsRealissimum said:
Oi, XJman. I think i saw you in another thread say that built blocks have to be rebuilt every 15k or so. I have no idea where I saw it so I wanted to ask if you recall it and what you meant by that. It's possible it was from years ago.
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It is a bit of hyperbole, but built engines are typically not long lived engines. I've personally not seen a built engine get the longevity zax suggested but people mistake power handling for reliability.

As the power handling capability goes up you give up certain things like super tight tolerance fits. There are always outliers but it's a good bet a built engine will not see anything remotely close to factory reliability.
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silver_scooby
Built engine is also a vague term. It could mean anything from upgraded conrods all the way to billet blocks with titanium pistons.

For moderate power levels, a lot of FA20 blocks keep oem case halves, liners (or alusil?), crank and head. All they change is closed deck inserts, wrist pins, rod bearings, conrods and sometimes pistons.

That said I know a gal with HKS FA20 shortblock with over 100k on the engine at ~400hp without any complaints.
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zax
XJman said:
I've personally not seen a built engine get the longevity zax suggested but people mistake power handling for reliability.
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I think boutique builders have come a long way in the last 2 decades, particularly on Subaru flat 4s. There are three things here that I think people always confuse - Reliability, Longevity, and Power Handling. Built blocks tend to have equivalent reliability, superior power handling but at reduced longevity. Example: an F1 engine needs to be rebuilt every couple thousand KMs so it's longevity is quite poor compared to a street engine, but it MUST be reliable during operation to be competitive.

XJman said:
As the power handling capability goes up you give up certain things like super tight tolerance fits. There are always outliers but it's a good bet a built engine will not see anything remotely close to factory reliability.
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And this is almost always due to the fact that a modern automotive factory possesses superior tooling that is out of reach of boutique builders. There are exceptions, like when the aftermarket acquires an entire factory line from the manufacturer. A rebuilt SBC from 1969 might have lasted as long as the factory block from the same era because of the crude factory tooling, but also remember that 100k miles back then was considered very high mileage. You and I know this because we've both work(ed) in the automotive tooling business. Most people do not.

I also think there's an issue with people "oversizing" a built engine for their needs. They think "well if I'm replacing the engine I might as well go with the block that can handle 1000 hp" not recognizing material choices may impact longevity. You should always choose the right combination of parts for the application. Not having clear and concise goals is the main issue here.
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zax
Companies like IAG have mad pretty major strides in extreme-tolerance machining, metrology, and assembly. I think 100k miles out of a mild IAG build isn't unreasonable.

That said, the warranty periods are always telling. Subaru warranties their engines for 5 years/60k miles while IAG warranties for 1 year/12k miles.

To be fair to IAG - Subaru knows EXACTLY what parts are going on the engine that is being warrantied whereas IAG does not.
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EnsRealissimum
zax said:
Companies like IAG have mad pretty major strides in extreme-tolerance machining, metrology, and assembly. I think 100k miles out of a mild IAG build isn't unreasonable.

That said, the warranty periods are always telling. Subaru warranties their engines for 5 years/60k miles while IAG warranties for 1 year/12k miles.

To be fair to IAG - Subaru knows EXACTLY what parts are going on the engine that is being warrantied whereas IAG does not.
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Haha, I am learning all of this at exactly the wrong time. I always just assumed that an aftermarket block that could handle 600hp or something would just obviously be long lasting beyond anything I would need.

When I decided to mod my car, I told myself I'd just get an AIG block if the engine ever blew up and that would be the end to all problems. I guess if that ever did happen I could just do something like Scooby said and get another OEM one and then replace a few parts to make it more capable of power. I can't imagine I would ever want to daily something with more than 400whp (at least not a wrx).
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zax
EnsRealissimum said:
Haha, I am learning all of this at exactly the wrong time. I always just assumed that an aftermarket block that could handle 600hp or something would just obviously be long lasting beyond anything I would need.

When I decided to mod my car, I told myself I'd just get an AIG block if the engine ever blew up and that would be the end to all problems. I guess if that ever did happen I could just do something like Scooby said and get another OEM one and then replace a few parts to make it more capable of power. I can't imagine I would ever want to daily something with more than 400whp (at least not a wrx).
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This is exactly the reason that the 2019+ STI block was so exciting to a lot of people.

OEM quality and longevity but potentially higher power-handling capacity.
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EnsRealissimum
zax said:
This is exactly the reason that the 2019+ STI block was so exciting to a lot of people.

OEM quality and longevity but potentially higher power-handling capacity.
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zax said:
This is exactly the reason that the 2019+ STI block was so exciting to a lot of people.

OEM quality and longevity but potentially higher power-handling capacity.
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Did it meet expectations?
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zax
Jury is out.

Lots of anecdotal evidence, but it's difficult to deconvolute real supporting evidence from the noise of the internet-o-sphere.

Example: a car could make 600whp on the dyno but blow the motor shortly after. Is that evidence of better "power handling?" The RA shortblock is still relatively new and doesn't have the history of all the EJ257s that came before to compare against. The same sort of thing happened with the release of the VA chassis. All of a sudden there seemed to be more 400whp+ STIs on the stock longblock than ever before, but did that have to do with the longblock or was it availability and quality of E85? Better Flex-Fuel options? More informed tuners with better ECU calibration strategies? Cylinder 4 cooling mod? Fuel rail kits that addressed resonance problems? It's impossible to decouple all this anecdotal evidence from a baseline truth. I will say... from a pure heuristics standpoint, the RA shortblock looks promising.

To add insult to injury, all these aftermarket companies are desperately trying to sell you their new miracle cure. Blast plates on 5MT transmissions, Cylinder 4 cooling mods, etc. etc. All of these mods SOUND logical, but a scientific demonstration of effectiveness is usually missing.
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