Two modified boxsters on the dyno

[itsnotanova]

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

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

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.

[j.fro]

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

[dijinn]

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

[Ciao]

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

[Cunningr]

Originally Posted by Ciao

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.

[The Radium King]

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

[78F350]

Originally Posted by The Radium King

...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) ...

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:

"... Below 3,000 rpm, the cylinders draw air from a “short” path. From 3,000 rpm to about 5,100 rpm – when the resonance flap opens – the cylinders draw from a long intake path, which boosts torque. Above 5,100 rpm, the flap again closes to allow the cylinders to draw intake air from a shorter intake path to boost horsepower at higher engine speeds."

[The Radium King]

Originally Posted by 78F350

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):

Dyno results!!

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

[itsnotanova]

Originally Posted by Ciao

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

The first graph is my friend's modified boxster. It has 249 at the wheels which is about 285-295 at the crank

Originally Posted by The Radium King

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

Originally Posted by The Radium King

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):

Dyno results!!

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

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

[jaykay]

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?

Originally Posted by itsnotanova

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

[The Radium King]

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

[mjannone]

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

[SoloPierre]

Originally Posted by mjannone

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.

[mjannone]

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

[edc]

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.