Josh B

He did. We weren't that satisfied with the results though - the car wasn't holding boost and the HP number wasn't where is should be. He was planning on tinkering with the car a little more and adding in some gauges to where he could do some data logging. Hopefully we can hit the dyno again soon.

Vendetta NY

Describes my scenario almost to a T. Only difference is I have no interest in huge power gains for my 968 because I have another car to do that with way more effectively.

Will not be changing the exhaust. So assume I only do the RS Barn chip and the airbox mod:
1. What gains approximately could I expect?
2. Are these the theoretical max gains for the mods, or are they limited because I'm not doing "supporting" mods like exhaust?

Is there anything else simple and invisible that I should do? Goal is to keep the car stock(ish), simple, and street.

-V

333pg333

You can get a fair hike in performance the naturally aspirated way...but it would be at the expense of a civil road setup. See HJK's build thread with a Michael Mount motor. https://rennlist.com/forums/924-931-...for-400hp.html

If you just chip or modify the airbox, you'd be lucky to see 10whp. Seems that there has been good success with supercharging kits. You can have your cake and eat it with one of these if well built.

Joel8005

Hmmmmm, Michael Mount, I have been told he knows how to build a motor.

Lear35A

The problem I encountered on the dyno was a slipping SC belt. It stated squealing at 4000rpm and the power peaked there. A run monitoring boost showed the boost peaked at only 3 psi with the slippage; it's supposed to be 5.
I have now tightened the belt and don't hear the squeal any more. I'm looking forward to getting back to the dyno.
Even with the slippage and low boost we saw 235rwp, so I'm optimistic. the SC definitely livens up the driving experience.

mikew968

My 968 is a track only car. it has a airbox mod in addition to the other mods mentioned. I am running pretty close to my class limit right now at 200 hp and 2900 lbs (with driver). the next class up is GTS-3 at 12 lbs/hp. That would mean 2800 lbs and 233 rwhp and approx 284 engine HP at 82% efficient. Sounds like no easy solution and spending 5-10k on a car worth 15-20k may not make sense. Forced induction generally does not hold up well in club level racing.

333pg333

Well you could do cams, pistons (higher c/r) , engine mgmt, maybe extrude hone the intake?

Cloud9...68

But that would easily run north of $5K, which the OP has said he doesn't think is worth it. Do you really think extrude honing would add any measurable horsepower? I've never heard of anyone trying it on a 968.

BikePilot

I would guess that a low-boost, intercooled supercharger setup would hold up fine even for racing (assuming fuel and timing were managed well).

I'm curious what could be done with some simple combustion chamber work. Perhaps tightening up the squish and CR a bit could be effective.

For a track car I think a light weight flywheel would make a significant positive improvement by allowing the motor to rev more quickly.

pmcrespo

Mike,

Once I decided to focus on PCA GT-5S for 2012 after NASA GTS-2 in 2011, I was forced to add a bit of power to close the 100 or so rwhp I was down vs. competitive air-cooled 911 race cars that have always dominated the class. So I added/upgraded some final key bolt-on parts to squeeze as much as (in my opinion) one can feasibly get out of these motors without touching the block (pistons, etc.).

The Dyno PDF: 2013 GTS Dyno Sheet SAE 4.pdf

I still think that at these power levels I cannot be race-competitive in GTS-3 against the better built e46 and Cayman S racers out there....

If you want more info, you know who does my work.... Reach out directly... I do not want to start any debates and/or drama here... not my thing... I am a driver... not a fighter!

And yes... NASA Compliant Dynojet Dyno at SAE 4. On a crappy hot day if you care to know.... perfect timing I have...

333pg333

No I've not heard of ex/hone on 968 either but I was trying to think of cheap possibilities. As far as cost goes, sure, nothing's for free. Running an n/a motor is just pretty hard work unless you spend big money. Not that forced induction is inexpensive but the returns are generally far greater.

odurandina

wouldn't it be cool if somebody manufactured a roots setup from the Ford Turbo Coupe for the 968.

and the engine would put 260 hp to the wheels and never break down.

well, since that hasn't happened yet, it's gonna have to be a turbo or v8.


when you get divorced, you need to work.

and you'll need a car that will get you to your place of employment without breaking down.

blue44

Pablo, what mods did you make to achieve those numbers ?

Donn

pmcrespo

Donn, the typical mods. Core being exhaust system, cams, tuning, etc. In my humble opinion, most critical is that they all work together. Complementary to each other and designed as a system rather than individual pieces alongside each other. It takes time, research, and a lot of trial and error to maximize the gains. In my case, the block is completely stock, never opened, and with many tens of thousand miles inclusive of at least 4 full racing seasons. So I presume others may be able to get more power out of a fresher block.

I don't want to sound secretive or selfish. Those who know me personally know I am not that type. But like I mentioned, I did not post to go into details of what I have, how I got there, and turn the thread into another battle of the mighty and in the process get chastised for marketing or advertising vendors, which will then just down-spiral from there. I just decided to post as a reference for Mike and all of you, on what I have achieved with "bolt-ons". It is no secret who does all my engine work, engine parts , and tuning.

Cheers!

mikew968

Thanks Pablo!

I am actually thinking of going over to the dark side...