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Cobb or APR?

68K views 218 replies 48 participants last post by  TNS_100 
#1 ·
Hi All, I have a 2018 718 Boxster GTS PDK. I've decided to tune the car. I have been researching both the Cobb Accessport V3 and the APR Tune. I do not plan on changing the stock sport exhaust. Based on numbers it seems like the APR tune provides more power. Does anyone have real experiences with these tunes and chime in, would appreciate it.
 
#147 ·
You can run high RON racing fuels in the 718 and the RON will be fine with the ECU and you should get the most power the tune is capable of (you should get no knock). But note that high RON racing fuels are typically bad for O2 sensors. So you may find you cause failure of the O2 sensor prematurely. They may also do bad things to cat converters?
 
#146 ·
Some of you are not getting the difference with ethanol. It does contain less energy, but to get to the same equivalent air-fuel ratio you have to inject more, so the energy ends up about the same. I have a WRX that has a flex fuel sensor... it can run any blend of ethanol. I mostly run it on E85. On E85 it injects about 30% more fuel to get to the same equivalent mixture ratio (lambda). I had to put much larger injectors in to run E85. This is for two reasons. The first is that I need 30% more fuel at the same boost. The second is that because of the much higher octane rating I can run higher boost (which requires more fuel again)... so I end up needing about 50% more fuel. The end result is that the car runs about 270kW ATW on 93RON petrol. On E85 it runs abour 330kW ATW. For normal around town driving, the fuel economy is about 25% worse (use about 25% more E85 for the same trip).

One other thing to mention is that the engine will run cooler (lower combustion temp) with E85 and you actually get a higher density of air in. Because you stick 30% more fuel in the engine, and that fuel needs to be vapourised, and turning a liquid into a gas takes energy, that energy comes out of the air going in and cools the air (kind of like water injection). Therefore the same volume of air contains more mass (and you need to stick even more fuel in to compensate). The combustion temps at the same power are lower as there is more mass in the cylinder to absorb the energy.

Now if you are using a certain fuel that is rated at a certain octain rating. Regardless of the composition of ethanol it will have that octane rating and that will cause a similar effect on the level of ignition timing you can run. The difference is that with ethanol, you have to put more in to get the same air-fuel ratio. So in a less advanced ECU it might run a little lean with say 10% ethanol. But late model ECUs have wide band oxygen sensors so they can sense the air-fuel ratio and adapt the tune accordingly. Of course with too much ethanol, the fuel system may not be able to cope with the additional fuel requirements.

My thoughts are that the 718 fuel system will cope with low amounts of ethanol (10%) at the power levels the turbo can support. But E85 is probably a no go. So mostly you just need to match the octane of the fuel you are using to the tune. Otherwise if you run a 93 tune on 91, the ECU will be continually adjusting the tune to prevent knock and that would provide inconsistent performance.
 
#157 ·
Unfortunately it is not a given that APR will work on any 718. I attempted recently to have my MY17 718S flashed in Australia and was unsuccessful as it is not yet supported on my ECU "type". It will probably be supported when someone can get an ECU to APR, but not yet. I am not sure if my ECU type is unique to Australia. I know another member from Australia was recently able to get a MY17 718S flashed with Cobb. Not sure if my ECU type is the same as his.
 
#162 ·
I increasingly only use the Cobb stage 1 (370bhp) in my 718 CS or even stock map in inclement weather, even though I’ve a custom tune (390 bhp). The issue is any more power than Cobb s1 and it’s hard to put down- accelerate hard and I get wheelspin, PSM light and if it’s slippery some back end fishtailing. It’s not a problem in that PSM sorts it out and avoided by being more gentle with throttle but it raises the question of what’s the point in having more power if you can’t readily deploy it.
The 911s I’ve driven don’t seem to have this issue, I guess due to more weight over the rear axle.
I don’t know the best solution. I’m considering changing Pzero N1s to Michelin PS4S (although no N rated in 19” in the UK) which might be stickier, or getting a CGTS- although unsure if that’d be any better (PTV perhaps). Maybe a heavy suitcase in the rear boot would help! Anyone else experience similar with power increases? Cheers
 
#163 ·
I increasingly only use the Cobb stage 1 (370bhp) in my 718 CS or even stock map in inclement weather, even though I’ve a custom tune (390 bhp). The issue is any more power than Cobb s1 and it’s hard to put down- accelerate hard and I get wheelspin, PSM light and if it’s slippery some back end fishtailing. It’s not a problem in that PSM sorts it out and avoided by being more gentle with throttle but it raises the question of what’s the point in having more power if you can’t readily deploy it.
The 911s I’ve driven don’t seem to have this issue, I guess due to more weight over the rear axle.
I don’t know the best solution. I’m considering changing Pzero N1s to Michelin PS4S (although no N rated in 19” in the UK) which might be stickier, or getting a CGTS- although unsure if that’d be any better (PTV perhaps). Maybe a heavy suitcase in the rear boot would help! Anyone else experience similar with power increases? Cheers
I’m not a big fan of the Pzeros. Just not as confident with them
 
#164 ·
Pzeros not good if you are trying to maximize performance. The grip is poor compared to other tires. Not near the same traction as say the PS4S... That is the tire I would put on your car, no question about it.

To give you an idea about traction, when going from the factory Pzero on my 718 Cayman S to Yokohama A052, there was a roughly 4-5 second difference between them on a 50 second course. Yes, the A052 is a 200 treadwear tire made for track and autocross, but 5 seconds is an eternity and the A052 are still a 200 tw tire.
 
#168 ·
i've had previous experience with cobb on my sleeper subaru sti that i owned some time ago for about 5 years with no issues whatsoever. i found the solution to be pretty solid for those who like to be more hands-on with modding their vehicle. the data logging was also a very cool feature and it helps in understanding what's going on with the engine a little better especially when adding or removing a part. while not the most technically advanced device, it is an easy interface to use for most people. it allows the user to see what codes come up when a CEL comes on, allows ecu resets, and (at least in the subaru's case) gave the ability to ignore some DTC codes when a mod caused a CEL. it didnt allow me skate through smog checks, but the CEL was not on all the time! i had a positive experience with cobb and would recommend it as a reliable and safe way to get most of what the engine was capable of. if you wanted to squeeze out every last drop of performance along with other mods, then pro-tuning was always an option which is nice to have. lastly, when i sold the cobb along with all the different OTS map versions, i got back about 75% of what i paid, so i dont think a return of half is the case, for this kind of mod especially, if it was kept in good to like-new condition like mine was complete with original box and all documentation.
 
#172 · (Edited)
I’ve recently changed my custom tuned 718CS for a 718 CGTS, added Cobb S1 and switched the Pirellis to Michelin PS4Ss. I’ve not put this on the dyno yet but assuming similar gains to the last one it’s likely to have about 380bhp and 360lbft (+20 bhp and +40lbft over stock). In my eyes the car is now more or less perfect; I’ve enough power to better exploit the chassis but without running in traction issues. The car still feels absolutely glued to the road, even in the wet, whereas my custom tuned CS would start to get a bit twitchy under hard acceleration. For the time being I‘m planning to leave it alone and just enjoy!
 
#175 ·
I had a Boxster GTS as a courtesy car yesterday, virtually identical spec to my cayman but on Pirellis and a 2020 car so has the petrol particulate filter/GPF. It was interesting to drive the two back to back. The grip of the Michelins is noticeably better, much more twitchy on Pirellis. As an aside the GPF quite dramatically strangles the exhaust- it is a lot quieter.
 
#176 ·
I've recently had my 718 GTS 2.5 Cobb custom tuned and have a couple of observations that may be of interest to those considering tuning. Previously I had a 718 Cayman S which was also custom tuned with dynos posted on this forum.
First, the GTS with its larger turbo does make more power than the S when tuned. Some tuners, FVD included, are quoting the same max power for both cars though. APR cite +60 bhp over measured stock for the GTS which seems about right.
Second, whereas I had traction issues on my S, this isn't the case with the GTS. I can put the power down with impunity now. Some of this might be down to the Michelins (I had Pirellis on the S), but the rest must be the chassis- PASM, PADM, PTV etc.
My conclusions is if you want to custom tune, the GTS is the model to go for the get the most out of it. Plus has 3rd inter-cooler so shouldn't overheat or limp etc.
 
#179 ·
Plus has 3rd inter-cooler so shouldn't overheat or limp etc.
Just clarifying that the turbo intercooling on the GTS is identical to every other model, but it has a 3rd radiator which is for engine coolant cooling. As fas as I know this only makes a difference at the track. I have yet to see anyone experiencing cooling issues in road driving.... so definately worth having if tracking. If it did have better turbo intercooling, that would be fantastic as a source of extra power.

I agree with the poster above that the traction difference is most likely tyres for straight line traction. Do you have dynos of the GTS like you had for your S?
 
#189 ·
Hey guys,

Mid 400s hp ATW sounds very high to me, but you seem to be using really good fuels like E30 which can add another 30hp or so. In other platforms I have experience in, I found that my local Australian Dyno Dynamics dyno tended to read lower than US commonly used dynos. What is the stock power you guys are making for those numbers? What is your estimate of flywheel power? My car is a 718S with APR tune (98/93 RON). Stock power was 300hp (225kW) ATW. 200 cell Downpipe+APR is 375hp (278kW) ATW. So gained about 75hp peak (and around 100hp in upper mid range). So I guess if I take the stock power claimed by Porsche (350hp) and add the 75hp, I would be around 425hp flywheel which is still lower than your claimed power ATW which seems huge. My results are a little better than claimed by APR, but I have downpipe which may explain that.

Anyway, just trying to find a way to compare my dyno results to yours when the dynos probably read differently.
 
#190 ·
Hey guys,

Mid 400s hp ATW sounds very high to me, but you seem to be using really good fuels like E30 which can add another 30hp or so. In other platforms I have experience in, I found that my local Australian Dyno Dynamics dyno tended to read lower than US commonly used dynos. What is the stock power you guys are making for those numbers? What is your estimate of flywheel power? My car is a 718S with APR tune (98/93 RON). Stock power was 300hp (225kW) ATW. 200 cell Downpipe+APR is 375hp (278kW) ATW. So gained about 75hp peak (and around 100hp in upper mid range). So I guess if I take the stock power claimed by Porsche (350hp) and add the 75hp, I would be around 425hp flywheel which is still lower than your claimed power ATW which seems huge. My results are a little better than claimed by APR, but I have downpipe which may explain that.

Anyway, just trying to find a way to compare my dyno results to yours when the dynos probably read differently.
My GTS made about 350whp on my dyno stock.

— Ed
 
#191 ·
Thanks Ed... your dyno seems to have a low drive train loss.... or maybe these cars are putting out a lot more than the claims from Porsche. Probably a bit of both. Either way, you have a 90hp increase over stock which is great, and sounds about right for E30 fuel over my 75hp increase on 98/93RON. What was your result on petrol before you went to ethanol blend? Also, you have GTS and I have S, so yours would probably respond a little better to mods with the larger turbo and intake. So the numbers make sense. Based on my dyno, I was predicting you had close to 500hp at flywheel, but probably closer to 460hp which seems more in line with what we know about turbo/fuel capacity on this platform.
 
#193 ·
Makes sense. APR claim about 20hp with 93 over 91. so:

  • Tune with 91 adds ~50hp
  • Tune with 93 adds ~70hp
  • Tune with E30 adds ~90hp

Downpipe adds another 5-10hp to above. Similar results for APR and well tuned Cobb (but not on Cobb OTS maps). I expect well custom tuned Cobb would add another 5-10hp over APR due to full customisation for car/fuel.
 
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