Two modified boxsters on the dyno
 

A friend of mine set up a local dyno event for European vehicles for $100 each. I invited a boxster friend of mine who also has a modified boxster to come along with his. Here's the info on his.
2001 3.2 with the six speed and 131,000 miles. He bought the car a few months back for $6000 and instantly started modifying it.
New plenum with air diverter and 74mm throttle body from Pedro's Garage.
DME bench tune
4 inch under drive pulley
Fabspeed headers, sports cats and muffler
https://www.youtube.com/watch?v=U5EEfdoYPC4
http://986forum.com/forums/uploads02...1522554689.jpg
He was very happy with his results.

I was up next with my highly modified boxster
2000 S with a six speed and about 65K
3.4 996 motor with intake and throttle body with 44k
987 airbox
996 ROW tune
Under drive pulley
Remote oil filter
Chinese headers
Custom made exhaust system using a 987 muffler
https://www.youtube.com/watch?v=ZJwESZUWt9A
http://986forum.com/forums/uploads02...1522555221.jpg
While I was ok with the 279.36 HP, I wasn't really digging on the slightly lean fuel ratio or the wavy gravy power curve.

Your friend's set up is very similar to mine and his number are just about the same, too.

Where are you connecting to get spark signal for the torque measurement? Wondering if you found an "easy" location to clip onto?

The first file shows the HP (about 250) of a Boxster S without mods.

You need to remember dyno gives rear tire horse power, the factory rated hp doesnt include drive train loss.

The figures are similiar to the before and after mods from fabspeed as well with similar mods.

interesting. any corrections entered for drivetrain loss (ie, this is actual wheel hp and not wheel hp adjusted to flywheel hp)?

otherwise, i would not worry about the afr readings - from what i've read, if they did the sniffer up the tailpipe approach the readings are not accurate; here's a quick search result:

tailpipe vs. wideband?

finally, looking at that 5500 rpm dip you have. i am trying to get my head around it. truegearhead had something similar. you see it on occasional dyno results. it may be an effect of scaling, as it shows up on the factory dynos also - ie, it just looks worse on a dyno that has an exaggerated 'y' scale. what is happening at 5500 rpm? the resonance tube closes again (opens at 3000 rpm, closes at 5000 rpm) and the variocam returns timing (advances timing at 1500 rpm, returns at 5500 rpm).

https://www.6speedonline.com/forums/996/205309-how-variocam-variocamplus-works-primer.html

Good points. That dip could just be a sticking/dirty/slow resonance flapper valve. Slight vacuum leak maybe? Electric valve starting to fail?
From an old Porsche archive:

so, perhaps i am overthinking, but with engine conversions, and with plenum changes, often the resonance tube has to be rotated/moved for clearance; operation may have been impacted? oil can pool in the resonance tube - if positioned other than oem, it may start to not operate properly. or perhaps they get weak over time and can't return properly when faced with 5000 rpm airflows.

the other thing i am thinking is perhaps the turn-over points are not optimal for modified engines - ie, perhaps the flap should close sooner? not close at all? i presume this is not something you can change with a tune, as jfro's result w softronic tune indicates (he's got the dip too):

http://986forum.com/forums/performance-technical-chat/37506-dyno-results-2.html

it would be interesting to dyno with the flap always open, and/or always closed, and see what happens with the dip.

The first graph is my friend's modified boxster. It has 249 at the wheels which is about 285-295 at the crank
Thanks. I'll look into the flap valve. I'm stuck on the AFR as mine gets leaner as the RPM's get higher and his gets lower. I kind of trust the readings as I've heard of a few 3.4 swaps having that issue. I plan on investigating that closer. As in another way of sampling and then what's causing it. I don't think a vacuum leak as it seems to rise with rpm. That really seems like a fuel delivery problem to me. I believe I changed the filter already. If I get confirmation from another source that I'm running lean then I might replace the fuel pump or jump up on the injectors. I'll have to see what's my best option

fuel pressure regulator? can handle lower flows but poops the bed when pushed hard?

I have recently done the 3.4L swap and my results are in between your and your friend's.

Starting last year I have dyno'd 4 times: starting from 2.5L stock then along the 3.4L upgrade path. The results are as expected based on the upgrade stages and based on other member's findings over the years.


2.5L - 100% stock 97K mile engine
Dyno'd (9/2017) at 170whp.

3.4L 996 66k mile engine swap - Softonic 996 tune, NHP headers, NHP mid pipes with race cats, stock 986 muffler, stock 986 intake.
Dyno'd (1/2018) at 239whp 214tq. AFRs were not good; 10.25-11.0. The dyno tech said the AFRs "were the worst he had seen in a while on a 996 or 986".

3.4L - Softronic 996 tune, NHP headers/mid pipes with cats, Beluga ebay muffler, stock 986 intake.
Dyno'd (3/2018) at 249whp 220tq. AFRs improved to 11.25-11.75

3.4L - Softronic 996 tune, NHP headers/mid pipes with cats, Beluga ebay muffler, 987 intake/MAF holder, 3.25" piping/silicone couplers, IPD plenum.
Dyno'd (4/2018) at 264whp 234tq. AFRs were excellent at 12.5-13.5

Between each dyno session, I researched/read discussions on this website for literally a dozen hours before making the parts/upgrade decisions. I set out to build a 300+hp Boxster and I believe I have finally arrived there. I believe there are probably another 10whp to find, but for now I am totally satisfied.

Thank You Thank You Thank You to all the contributors to this great website.


Regards,
Marc

What did you Dyno on? Dynojet, Mustang, or ?

If you used a Mustang, multiple by 1.1 to get a number that somewhat compares to a Dynojet.

It was a Dynojet at Superior Automotive in Placentia (near Anaheim).

Wood,

3 questions regarding your friends 3.2

Where are the cats in his exhaust system? Does he have fabspeed headers with cats incorporated or are they in the mid pipes?

What is the nature of his DME bench tune?

What is the drivability / throttle response of his car like below 4000 rpm?

What's the diameter of your exhaust system? The the biggest problem with the 986 exhaust system is that it's way too small. That's why I used a 987 muffler. It's the same diameter as the 996
JayKay,
He lives in an area with emissions and has the pre-cats but not the secondary cats. He said he had to send his DME off to some place out in Germany but didn't tell me much more. He believes there's a quicker throttle response with the larger 74 mm throttle body.

[QUOTE=itsnotanova;567122]What's the diameter of your exhaust system? The the biggest problem with the 986 exhaust system is that it's way too small. That's why I used a 987 muffler. It's the same diameter as the 996

I purchased the NHP headers and mid pipes from Softronic (DME tuner) as part of the 3.4L conversion package. Softronic's website says the headers are 42mm primary piping (vs. 34.5mm for stock) with a 53mm exit pipe (vs. 42.5 for stock), and the mid pipes are 50mm (vs. 40mm for stock). These all appear to be an improvement over stock.


I am using the stock small-diameter U pipes that connect the mid pipes to the Beluga ebay muffler. There clearly is room for improvement here as these stock pieces are 40mm in diameter.


I am curious to know if the more restrictive, but larger diameter 987 muffler you have is a better performer than the less restrictive, but smaller diameter Beluga ebay muffler. I do know the Beluga muffler sounds insane at WOT where it is a full-blown race car soundtrack. Neighbors (and most wives) will object. It has calmed down a bit in the 400 miles I've put on the car since installing it, however there is no mistaking that its a performance car now. When I had the stock 986 muffler on the 3.4L, there was virtually no difference in sound from the 2.5L. It was quiet and unassuming, and obviously down big time on power.

Thanks Woody,

I am surprised that the 3.2 is up to 290 with cats in the headers......and stock air box

[QUOTE=mjannone;567143] Post 185 of my build thread http://986forum.com/forums/show-tell-gallery/59449-woodys-build-thread-5.html, I go into detail about my exhuast system. You'll have to use Google Chrome to see the pictures. I'm thinking your problem is the factory U-pipes. You're only as big as your smallest opening. My whole system is 50mm or larger throughout and has a smoother path than the factory 986 or 996 system. I'm thinking the system I built might be less restrictive than the 996 system as I made more power than a factory 996. That's if the dynojet was correct. That also might explain the lean running condition. More air in and out but no increase in fuel.

OEM 986/996 injectors are only 230cc/min if I'm not mistaken which IMO are woefully undersized and at the practical limit. At 100% duty cycle and a fuel pressure of 43.5psi 6 230cc injectors are theoretically only good for around 290bhp.

I'm not surprised to hear about modded 3.4 lean issues at all. You should be completely out of injector given the math.

**edit**

I just found that fuel pressure in a 996 is actually 55psi, so that should give a little more headroom, like 6 more bhp.

I'm surprised Porsche put such a small injector in these cars. I've always been under the impression you really don't want to run an injector more than 80% IDC just so you have some additional margin. That would mean you really want an injector around the 290cc mark. That would run a motor comfortably at 300bhp and give you room to grow up to around 370bhp.

What do folks with 3.2s modified for 3.6 or 3.8 do for injectors....don't ever hear about capacity issues

So the real question then is if Woody's boxster is setup up for 55psi or not.

Mike

There's a chap on Boxa.net who built his 3.2 into a 3.4. He's a mapper and engine builder by trade and he had no issues with injector duty cycle as far as I know.