Dyno dissapointment

[adamlittman]

Just did chasis dyno on my 79 911 lt wt power at the wheels was 207hp/222 tq. Feeling a little disapointed as the car feels like a monster on the road and is very competitive for DE time trials. At 2550lbs with fuel and driver this thing pulls like a super car and gets it done reliably. Thoughts???

[juanbenae]

rather vague. what have you done to the motor, induction & exhaust? if in OE trim 207 is rather impressive.

[Ton504]

Whats your engine setup?

[adamlittman]

3.4 /906 cams/Weber 46/electromotive xdi/twin spark heads/1.75 headers with 5x14 magnaflows.

[gliding_serpent]

Compression?

Could be many things, including tuning/timing. But I agree, not so great results. I would expect 230hp (270rwhp) maybe 5-15 more.

What dyno type? Take the numbers with a grain of salt.

[adamlittman]

superflow windyn v3.2

[adamlittman]

This was 3rd gear which the guy said was my 1 to 1 gear.

[gliding_serpent]

Injectors?

[Sicklyscott]

I'd expect more as well. Can you post a dyno graph with AFR? It may need tuning with the carbs.

[adamlittman]

I have dual AFR in-dash and fuel is good.

[Duc Hunter]

3rd gear is your 1:1? Seems strange to me?

[adamlittman]

911SC 1978-79

5-speed synchronized transaxle

Manufactured by Porsche (ZF)

Plate-type limited-slip differential available

Rod shift

Single-plate clutch

Gear ratios:

1st gear: 3.18 (11/35)

2nd gear: 1.83 (18/33)

3rd gear: 1.26 (23/29)

4th gear: 1.00 (26/26)

5th gear: 0.82 (28/23)

Ring and pinion: 3.88 (8:31)

[Charles Freeborn]

If you're pleased with the performance, why worry about the numbers?

[adamlittman]

Great comment, CF!

[Cory M]

Seems very low to me. I had a similar 3.4 without the twin plug (but without mufflers too) and I was disappointed when it it pulled 235HP on the chassis dyno (after a few racing seasons). Steve Wong's website has a bunch of dyno sheets on it if you want too see plots from similar engines.

[Steve W]

What brand of dyno was it? If it wasn't a Dynojet, but a Mustang, Dyno Dynamics, Dynapack, or worse, some off brand like Land and Sea, the numbers can be all over the place, up or down 20% depending on how the operator sets up the load factors, ramp rate, fudge factors, etc. What is the compression and did you get an AFR curve?

[Reiver]

Wrong gear.....

[juanbenae]

Originally Posted by gliding_serpent

Injectors?

I don't reckon injectors are in play with carbs.

[gliding_serpent]

Originally Posted by car 311

I don't reckon injectors are in play with carbs.

Yeah i missed that... Unless he has carbs and injectors!!!

[0396]

Interesting.