Limits of stock turbos HP wise

[Rh7644]

Question…it may have been answered; I did a quick search and could not find it.

I’m thinking about doing a full bolt on build at the moment stock turbos (I may upgrade turbos and do a hpfp and injectors eventually).

That being said, what are the stock turbos good for HP wise?

Assuming I do full bolt ons…down pipes, exhaust, cold air intake, intercooler and tune, what HP numbers should I expect? Would that put me at the limits of the stock turbos? Am I missing anything on this application performance wise before having to upgrade to larger turbos, injectors, fuel pump?

Will a full bolt on build (prior to upgrading turbos fuel pump and injectors) put me into the 11s (AWD application) ?

Here is what I’m thinking about doing to try to max out stock turbos. Please let me know if I’m off…

Thermal r&d exhaust-

Fen fab catless downpipes-

Whipple intercooler-

Afe momentum GT CAI-

ZFG racing tune e50-

ZFG second tune for 93


thanks.

 

[TMac]

You'll get plenty of opinions on this subject- here's mine, and these numbers have been documented many times. With an absolutely stock ST, a good 93 tune (ZFGRacing) can provide you with about 440 AWD hp, up from about 340 stock. (YMMV). That will put you into the low 12s in the 1/4 if you care about such things. Using the same stock ST, an E50 tune will net you around 500 AWD hp- and is enough to put you in the high 11s.

Based on this information, and the dyno numbers showing that wastegates are opening below 3000 rpm, this demonstrates to me that the stock turbos are maxed at about 45-50 lbs/min of airflow AND that you don't need any bolt-ons to to hit the stock turbos capabilities.

Sure, you can add bolt-ons and pickup a few hp here and there and drop a tenth or two, but it's not necessary. If your goals are low 11s, then you're going to need the bigger turbos, injectors, pump, intercooler, downpipes, and intake (AFE). That's a LOT ($5k-$7.5k plus labor) more money for those gains.

 

[Rh7644]

You'll get plenty of opinions on this subject- here's mine, and these numbers have been documented many times. With an absolutely stock ST, a good 93 tune (ZFGRacing) can provide you with about 440 AWD hp, up from about 340 stock. (YMMV). That will put you into the low 12s in the 1/4 if you care about such things. Using the same stock ST, an E50 tune will net you around 500 AWD hp- and is enough to put you in the high 11s.

Based on this information, and the dyno numbers showing that wastegates are opening below 3000 rpm, this demonstrates to me that the stock turbos are maxed at about 45-50 lbs/min of airflow AND that you don't need any bolt-ons to to hit the stock turbos capabilities.

Sure, you can add bolt-ons and pickup a few hp here and there and drop a tenth or two, but it's not necessary. If your goals are low 11s, then you're going to need the bigger turbos, injectors, pump, intercooler, downpipes, and intake (AFE). That's a LOT ($5k-$7.5k plus labor) more money for those gains.

Thanks for the info. Are you saying that on e50, you are close to the stock turbo limitations?

I’m thinking I’ll knock out the supporting mods now and when I’m ready to go larger turbos, I can just do the hpfp and injectors and be done.

I’m coming from an 18 e63s amg where I had pure 1000 turbos making 820 whp. I know this is a different ball game, but I appreciate the fact you can get a loaded st for around 60 and do a few mods and get into the high 11s relatively cheap

 

[twin001]

Whipple IC and ZFG e50 tune alone has put a few ST owners in the 11s. I have run multiple 0-60 at 3.7s and 1/4mi passes at 11.8 @118mph with IC, ZFG e50, and FenFab intake/downpipes.

the biggest limitation is the fuel system (injectors and HPFP). Once you do that you would want to consider beefing up the transmission (Level 10). Once you do this then go upgraded turbochargers.

 

[TMac]

Thanks for the info. Are you saying that on e50, you are close to the stock turbo limitations?

The mass airflow number is independent of the fuel. If you take a look at the dyno torque curve of a tuned car, you can easily see peak torque at or before 3000 rpm- meaning peak boost has been reached and wastegates are opening. That is clue one as to turbine wheel/housing size which is one indication of potential. The airflow number at that point is approx 30 lbs/min. From there, peak torque continues to fall gradually (based on some excellent tuning btw) until peak airflow is reached around 45 lbs/min. So the stock turbos are maxed out as I said around 45-50 lbs/min. I haven't seen any correlating IAT numbers, but this would be an indication of compressor efficiency which would also be a limiting factor.

Also, as @twin001 says, stock fuel system FOR ETHANOL is already pretty much maxed out on the stock turbos at 500 AWD HP.

 

[Rh7644]

Ok

The mass airflow number is independent of the fuel. If you take a look at the dyno torque curve of a tuned car, you can easily see peak torque at or before 3000 rpm- meaning peak boost has been reached and wastegates are opening. That is clue one as to turbine wheel/housing size which is one indication of potential. The airflow number at that point is approx 30 lbs/min. From there, peak torque continues to fall gradually (based on some excellent tuning btw) until peak airflow is reached around 45 lbs/min. So the stock turbos are maxed out as I said around 45-50 lbs/min. I haven't seen any correlating IAT numbers, but this would be an indication of compressor efficiency which would also be a limiting factor.

Also, as @twin001 says, stock fuel system FOR ETHANOL is already pretty much maxed out on the stock turbos at 500 AWD HP.

perfect. That makes sense then that limitations of stock turbos is independent of fuel system. And e50 limitations are around 500whp. Anything more than that upgrade fuel system and turbos. Got it.
What are we seeing on upgraded turbos and fuel system? Low 600whp and low 11s right? Anything more than that I’m assuming you’d have to upgrade the motor at that point?

 

[UNBROKEN]

Plenty of people are actually seeing closer to 540-550 whp on E50 with supporting mods…you’re running out of air about there.

 

[TMac]

What kind of supporting mods? I only ask because ethanol is definitely forgiving when it comes to running way to the right on the compressor efficiency curve. But that doesn't mean it's safe or effective long-term. I'm not on the FB forums, but have certainly heard anecdotal evidence of ZFG backing down E50 tunes due to the AFE airbox being better than I would have guessed. Share more please.

 

[UNBROKEN]

Just the usual…downpipes, etc.
Plenty of guys have been in that range on the dyno and backed it up with Dragy/track times. I prefer et/mph/weight calculators to dynos myself. I finally installed my AFe weekend before last…haven’t even driven it yet. I guess I need to get Adam a log soon.

 

[TMac]

Just the usual…downpipes, etc.
Plenty of guys have been in that range on the dyno and backed it up with Dragy/track times. I prefer et/mph/weight calculators to dynos myself. I finally installed my AFe weekend before last…haven’t even driven it yet. I guess I need to get Adam a log soon.

The only Dragy times I've seen under 11.8 on stock turbos was with an upgraded fuel system. Not saying it can't be done- 50 lbs/min (my max estimate) on the stock turbos on a higher than 50% ethanol mixture could definitely do that but the shaft speed on those turbos would be scary. I wouldn't make guesses as to turbo longevity!

 

[TMac]

I have to apologize as I underestimated the stock lbs/min mass airflow. Found an error in my spreadsheet (fat finger typing) after I looked at it causing a difference of about 12% or 6 lbs/min. Doh. So, the actual lbs/min estimate would be 51-56 lbs/min of airflow. This does NOT change the wheel HP estimates or dyno numbers I reported above, but it does mean that with an upgraded fuel system on ethanol with the stock turbos it would be possible to see over 500 whp.

 

[zdubyadubya]

also, it was glossed over above but ZFG won't provide you a tune with catless downpipes. not only are they 100% unnecessary, but they are just asking for trouble in this day and age. the cats will NOT be the limiting factor on any ST build.

 

[Rh7644]

Just the usual…downpipes, etc.
Plenty of guys have been in that range on the dyno and backed it up with Dragy/track times. I prefer et/mph/weight calculators to dynos myself. I finally installed my AFe weekend before last…haven’t even driven it yet. I guess I need to get Adam a log soon.

When you say the usual downpipes etc…do you mean downpipes, cold air intake, whipple ic…but no fuel system upgrades (no HPFP/ injectors)?

Is the AFE GT that good at cooling and moving air that guys are seeing above 500whp? And I agree dragy and drag strip et/mph is the true king but dyno numbers are still fun.

are these exhaust systems more for sound than anything or are people seeing gains with them as well (thermal/ borla etc)

 

[Rh7644]

also, it was glossed over above but ZFG won't provide you a tune with catless downpipes. not only are they 100% unnecessary, but they are just asking for trouble in this day and age. the cats will NOT be the limiting factor on any ST build.

I figured as much due to the EPA cracking down. I guess it’s not like the days of old when catless was the way to go. Thanks!

 

[UNBROKEN]

When you say the usual downpipes etc…do you mean downpipes, cold air intake, whipple ic…but no fuel system upgrades (no HPFP/ injectors)?

Is the AFE GT that good at cooling and moving air that guys are seeing above 500whp? And I agree dragy and drag strip et/mph is the true king but dyno numbers are still fun.

are these exhaust systems more for sound than anything or are people seeing gains with them as well (thermal/ borla etc)

Correct. There’s tons of us running 11.6-7’s at 117/118 at full weight with pano roof, etc. Including driver weight, 265lbs in my case, that calculates to roughly 540 at the tires on E50 with stock fuel system and turbos. In my case that was long before the aFe intake…I haven’t retuned for that…or even driven it. It’s not my daily driver.
And again correct on the exhaust. There’s some power to be had with high flow downpipes but the exhaust after that is just to pick the noise you wanna listen to. I personally wanted a deep tone so I built my own dual 3” system. In all honesty the factory dual 2.25” will support this amount of power without breaking a sweat…it’s just ugly. lol

 

[Rh7644]

Correct. There’s tons of us running 11.6-7’s at 117/118 at full weight with pano roof, etc. Including driver weight, 265lbs in my case, that calculates to roughly 540 at the tires on E50 with stock fuel system and turbos. In my case that was long before the aFe intake…I haven’t retuned for that…or even driven it. It’s not my daily driver.
And again correct on the exhaust. There’s some power to be had with high flow downpipes but the exhaust after that is just to pick the noise you wanna listen to. I personally wanted a deep tone so I built my own dual 3” system. In all honesty the factory dual 2.25” will support this amount of power without breaking a sweat…it’s just ugly. lol

Thanks for your knowledge with this platform.
Do any of the larger exhaust companies make a 3” for this platform? I’m looking at thermal but I want that deep tone as well. I don’t want it to sound like a rice rocket.

 

[UNBROKEN]

Thanks for your knowledge with this platform.
Do any of the larger exhaust companies make a 3” for this platform? I’m looking at thermal but I want that deep tone as well. I don’t want it to sound like a rice rocket.

2.5” is as large as anyone sells.

 

[Rh7644]

2.5” is as large as anyone sells.

Dang ok thanks.

 

[nzaf985]

Dang ok thanks.

CP-E will be releasing a 3” exhaust soon we should see/hear the prototype in the next 2-3 weeks.

 

[TLST22]

Just the usual…downpipes, etc.
Plenty of guys have been in that range on the dyno and backed it up with Dragy/track times. I prefer et/mph/weight calculators to dynos myself. I finally installed my AFe weekend before last…haven’t even driven it yet. I guess I need to get Adam a log soon.

Adam didn't revise my 93 tune after installing my aFe CAI, that was after I sent him logs as well. Not sure if it's because I'm on a 93 tune? He said it everything looked good but I thought a lot of folks who have the aFe CAI did get some sort of revised tune for theirs? Input?