PorscheAddict

Thank you

ChicagoSpeed996

@Charles Navarro would you recommend putting the fuel additive in a tank of fuel before a oil change or does it matter?

Charles Navarro

If the car has been maintained with regular fuel system treatments since new or rebuilt, I'm fine with doing it at the same time as the oil change. If you are doing a double dose or are trying to address some problem, it's probably best to do the oil change after that tank of fuel. I'd recommend doing used oil analysis using our partner Speed Diagnostix if you suspect something is wrong with the engine.

Rich_Jenkins

So sorry to hear about this, OP. I bought a used '14 981 this summer and now have 49K miles. Knock on wood no issues yet.

Just wanted to also thank all the folks in this thread; it's been pretty informative especially the posts about fuel additives and not letting the tank get below 1/2. I will definitely be looking to make sure the oil temp is normal before getting above 4K.

One follow up on the fuel additive? Is there a ratio of oz's of additive to full tank? I see 8 oz bottles of "Driven" additive on Amazon but I wasn't clear is this was a "add a couple oz" or "dump in a bottle" type thing.


Rich

ETA: Sorry I should have looked further - looks like 10 oz treats 25 g, per the manufacturer's web site.

Sorry for noob question.

AlexNY

Hello! Im in kind of similar trouble right now. So, how your problem resolved?

deilenberger

Hi, welcome to the forums.

I'd suggest you post a NEW thread with your problem explained in it. The person you are asking was last on Rennlist on 12-21-2018 09:34 AM - chances are good he isn't going to see your posting.

AlexNY

Oh, ok, I’m regret at 2018, but not use this forum till problem become. Yes, I’m noob here. Thank You for advice

Mike127

Looks like he beat the odds! For I am here.


Anyways, I had the head pulled out, failed injector replaced, fuel lines and sensors checked out, etc. In the end the slight scoring in the cylinder was considered not enough to replace the engine.

I ended up selling the Porsche a few months later because I didn't have peace of mind (hence away from the forum). I'm now on the Lotus train, but a GT4/GT3 will be in my future.

Sub

I stopped reading when I saw COBB. They tanked my 08 sti too with a badly managed tune on a 8k mile car. Zero trust in that company (Dont care if they are a forum sponsor)

cjrhoades

Not trying to take a side for or against Cobb, but I wouldn't think any tune would be able to cause bore scoring after just a month and 1500 miles.

okie981

I have no experience with Subarus, but I had a Cobb on my 981 Boxster S for 23k miles with ~3,500 of those on track and I never had a single issue whatsoever. I removed the tune when I retired my car from track life about 1,000 miles ago.

Do you have specific data or details that prove the Cobb caused the problem with your STi or are you assuming that correlation proves causation?

Noah Fect

Interesting. Why'd you do that?

donR

Do these tunes really actually make that much difference to an NA engine anyway? Unlike the turbo engines.

cjrhoades

Not a large difference, no. Usually an extra 15-20hp on the 2.7 and 30-35hp on the 3.4 non-GTS. Add another 10hp to those if you've got a Boxster since they came factory detuned. Best case scenario is a Boxster S where you'll gain 40-45hp for ~$1200.

ICNU

You can get up into the 360-370HP range with a good pro tune and sport headers on a 3.4 engine. Things like aftermarket TB and plenum are good for another 5 or so peak HP, but way up near redline and only in conjunction with a proper tune. Catless race headers vs sport cats headers are good for another few HP, so 370-380 is the upper limits for what you can expect naturally aspirated and what some tuners in Germany are managing to squeeze out of them.

High flow sport headers and a proper tune will give you the most bang for the buck in the RPM range where most will be driving a street car, so you have to decide if the extra 10HP or so from a TB/plenum change and race headers at 7,000 RPM is of any value to you if you aren't tracking the car. The 45 or so HP that can be gained for street use is definitely enough to notice, but is going to set you back 5K or so