3.2L to 3.5L - Part III (DYNO!!!)

[Carrera3.5L]

Well, it's time to put up or shut up. No more bench racing for me, it's time to see the cold hard truth about what the 3.5L motor actually does.

Fortunately, the planets aligned and I was able to schedule dyno time at Vision Motorsports in Laguna Hills, CA on Wednesday the 29th AND have the added pleasure of Steve Wong coming down (again!) and offering to help further tweak the motor.

To recap, here is the 3.2L that I started with in early September. Baseline dyno figure on Vision's 248C was 199 rwhp with a Steve Wong chip, Dansk pre-muffler and Dansk single-in and dual out stainless muffler:



Here is the now 3.5L that went back in the car in early December:



Here are the build details (the short version):

3.5L displacement using Mahle 100mm pistons & cylinders
Measured 9.5:1 CR
Cylinder heads polished only (not ported)
Twin-ignition using 993 distributor & Andial signal splitter
Engine case boat-tailed and shuffle-pinned
100mm cylinders mooned
ARP head studs
ARP rod bolts
AASCO Performance valve springs
Web-Cam 20/21 camshaft profile
Magnecor KV85 8.5mm custom spark plug wire set
Extrude Honed Intake Plenums
Bored throttle body
1 5/8" European Racing Headers by George equal length headers
Dansk 2-in & 2-out stainless muffler w/ 84mm tips
Custom/optimized Steve Wong chip

The motor will be dyno'd on the exact same dyno it was baselined on and will be as it will run on the street, namely using 91 octane pump gas.

It will be dyno'd again at a later date on a different 248C that is also local to me, just for the sake of comparing the numbers.

My goal is 238 rwhp (which if you ASSUME a 15% drivetrain loss) is 280 flywheel horsepower, which is 80 hp/liter where Porsche's most powerful street motors have traditionally hovered.

I will be pleased if I meet my target, disappointed and will find a way to if I don't, and jump up and down if I am significantly over.

So, without further adieu, WHAT DO YOU THINK THE MOTOR WILL PUT OUT AT THE WHEELS GIVEN THE INFO ABOVE???

WILL I GET THERE?

[Eagledriver]

231 RWHP.

-Andy

[Lukesportsman]

certainly "LOOKS" like 280hp! Nice Good luck.

I can't answer your question, but the motor sure looks nice. Hope you get the results that you want!

[addictionMS]

232 RWHP, he, he, he....

[JeremyD]

229.8 rwhp. You'd be at your goal if the cr didn't come in a little low...

[ZAMIRZ]

If possible I'd like to come see you dyno and possibly take a ride in your car since I will be in the area on Wednesday. What time is your appointment at?

[MotoSook]

I think 280 is possible... Good luck Ralph!

[Craig 930 RS]

247.5

Gonna be close!

[jpahemi]

What a tease; I saw the thread and couldn't click fast enough on it, then I see we have to wait 'till the 29th. Damn!
J.P.
Ps. Ralph: the clip/bracket that holds the TDC, crank position and cyl. temp. leads is on backwards.

[jpahemi]

Ralph:
Mine has never been off:

j.p.

[Carrera3.5L]

Originally posted by jpahemi
P.s. Ralph: the clip/bracket that holds the TDC, crank position and cyl. temp. leads is on backwards.

No kidding! Now you tell me! Should I tell you guys that I have an extra rod bolt left over?

[MotoSook]

Originally posted by Carrera3.5L
No kidding! Now you tell me! Should I tell you guys that I have an extra rod bolt left over?

LOL..in that case...I estimate 29 HP..then stand back!

[Porsche Doc]

I have a 248 and I have learned not to guess.
But you will be close! Torque should be nice. Press the petal HarD!
Only 1 question.
Why didn't you go with a higher compresion?
With the twin plug setup you could have easlly gone up to 10.5 ot 11 on pump gas.

Good Luck Man!

[jpahemi]

Ralph:
I saw it when you posted a pic of the engine complete and totally forgot, besides I didn't want to sound like a smart ass.
Regards,
J.P.

[jpahemi]

BTW:
What happened to this bracket?? That's another 15 hp. :~()



j.p. (smart ass)

[Carrera3.5L]

Originally posted by Porsche Doc
Only 1 question.
Why didn't you go with a higher compresion?
With the twin plug setup you could have easlly gone up to 10.5 ot 11 on pump gas.

Good Luck Man!

Long story, too long to post again. Check out my 3.2L to 3.5L Part II thread for the whole story. Cliff notes version is that the Mahle 100's were advertised at 10.3 but actually measured out at around 9.2. Milled .020" from the heads to get back to 9.5.

No way can you run 10.5-11 CR even with twin-plugs on 91 octane here in California (at least for any length of time). No knock sensors on 3.2L motors to help my ears in case of detonation.

Ralph

[rdane]

Best of luck! Either way nice motor. I bet it is a hoot to drive. Ralph what is your car's weight?

[Steve W]

Let's hope you do at least 238 rwhp! I've got 3.2s pulling 226 and 235 at the rear wheels, dynos sheets online here. In Bruce Anderson's book, pgs 150-151, Jerry Woods built a twin plug 3.5 from Carrera 3.2 engine that put out 252.1 hp at the engine, and I think we should better that significantly.

[Carrera3.5L]

Originally posted by Steve W
Let's hope you do at least 238 rwhp! I've got 3.2s pulling 226 and 235 at the rear wheels.

Thanks Steve, you are killing me! See you on Wednesday!

Vision's 993 twin-turbo race car just saw 668 at the wheels last week after the installation of ITB's and some MOTEC tuning. Maybe I should mix-up the dyno sheets???

Ralph