Rothsport 3.0/ITB/3.6 Intake/Motec M84 build

[rsscotty]

This is a 3.0 SC engine that had carbs. It is now as shown, total rebuild with new Mahle P&C, Elgin cams, stock large port heads, 1 5/8 headers, Dansk Sport muffler, Bosch 3x2 coil, Huco 3 channel ignitor, Motec M84 with Bosch LSU 4.9 oxy. sensor.
Coil and ignitor mount plate will fit in the center of the shock tower cross-member under the air filter.

Should be running sometime Monday to do engine break in and mapping.

Engine is going into a 73 911T...super clean car.

[jmh61]

That is very cool... Is it for a street car? See the single outlet muffler but no heat.

Sequential injection? What injector size? Jevey TBs? TB linkage is different, does it operate something in the plenum?

What kind of HP and torque is expected?

[rsscotty]

The car is going to Florida, so the owner does not want heater boxes.

Jenvey throttle bodies with nothing going to plenum as far as the linkage goes.
The linkage is a Rothsport design specific to fit the Jenvey trottles. 964 intake with resonance valve switched by ECU at specific rpm. Airflow straight in to the custom intake tee behind air filter.

Wasted spark ignition, non sequential injection firing in grouped pairs.

Our Spec 911 class engines are around 260 hp, so this should be that or more since we are using a slighter bigger cam than the spec engine.
Engine will be tuned for premium unleaded pump fuel...running closed loop lambda.

Injectors are EV6 Bosch 27lb.

[rsscotty]

[toddu]

Flywheel numbers?

[rsscotty]

Flywheel numbers is correct.

Superflow engine dyno.

[jmh61]

Like that torque curve.

[rsscotty]

Completed project...engine in car.

The owner is presently driving it to Seattle, then to Chicago.

[Walt Fricke]

Is that a modified Vario-Ram intake plenum system? From a 993?

Does dyno data show that this gives a better torque curve (like the wonderfully flat one here) than just six stacks with carb style air filters on each side?

[rsscotty]

Hi Walt,

This intake is off a 964. We use a modified tee plastic piece to attach the air filter. This is the same plenum as a 95 993 except the two differ in the resonance flap..one being normally closed and the other normally open, so you have to configure the software to match what mode you want it in. This system is pre-varioram era.

I can post a dyno overlay comparison of a Spec. 911 3.0 build with carbs compared with this resonance system on a Spec. 911 3.0 so you can see the difference in the torque curve if you like.

[PFM]

Scotty,

Please do post a comparison. What Elgin cams are used on this motor?

[rsscotty]

Elgin Super C2

[rsscotty]

Originally Posted by Walt Fricke

Is that a modified Vario-Ram intake plenum system? From a 993?

Does dyno data show that this gives a better torque curve (like the wonderfully flat one here) than just six stacks with carb style air filters on each side?

This is an overlay of two identical long blocks. The carbs do better on top as would our EFI with straight stacks, but I'll take the torque the EFI and 3.6 plenum has over a little more top end hp. The EFI is much more thrifty with fuel compared to carbs. with their typical rich trench in the midrange rpm.

[PFM]

RSScotty,

Thanks for the information very informative and mirrors what I have seen as well. Sad and happy to see your TQ fell off past 5800 with the plenum in place, as did mine. Not spinning it to 8000 to make power should help keep it alive as well.

[304065]

Bob, now THAT is some useful data, thank you very much for what must have been a time consuming analysis. Bravo.