Tripster

What can cause my car to get 11.1 MPG on th HWY?
Car run's 2800 RPM @ 80 on the interstate. Most of the time it is pulling vacume and no boost, motor is very mild,
K27, .7Bar, Euro CIS, Euro exhaust, 964 cams, Duel outlet muffler.
Timing is set @ 5 ATDC the CO is 3.5%
Fuel system new WUR, new CSV.
Cold 26 psi
warm 50 psi
System 89 - 90 psi

Please give me input, this car is leaving for a trip to the Dragon on Friday.

Geoffrey

Timing set to 5 degrees ATDC???

Tripster

I may be wrong in my wording, but if your looking down at the pully from left to right you have
10 5 0 with the motor turnig clock wise. It is set @ 5 @ 900 rpm

Geoffrey

Yea, that is BTDC, not ATDC. The proper way to determine timing is at 4000rpm with the vacuum line disconnected and depending on year and US vs ROW, it should be 26-29 degrees BTDC +- 2 degrees.

Tripster

Thanks, I can put some timing tape on it and set the total timing to those specs, Any idea on the 11.1 MPG?

Geoffrey

Turbos that have been modified require the CO to be set rich so it does not surprise me that the fuel economy under cruise is bad. I don't really know if 11mpg all that bad.

A930Rocket

11 mpg?

I get like 3 mpg on the track.

PorschePhD

Seems a little off. My 930 gets about 18 during cruise.

bogey1

The 965 the Good PhD built me gets around 10-12 MPG highway, so its not that far off. Mine is a little more built, and runs at 1.0BAR, but has a 5 speed geared pretty low.

PorschePhD

You guys know that cruise does not include 1 bar of boost don't ya

bogey1

Yep, but I never get to cruising speed without it!!! What fun would that be??

DonE

My modified CIS 930 got between 16 - 18mph hwy, 11 around town.

Tripster

This is very laid back driving, not into the boost at all.
Also, I am into this thing right now looking for a vacume leak somewhere that may cause the rough start up and this is all I have found. No obvious leaks, but when spraying starting fluid in various points, I found when I spray the AAV the motor will not speed up but it does smooth out a bit, after 10 seconds it will idle ruff again, then spray again and it will smooth out, any thoughts?

srf506

I concur with Steven. My completely stock, 85 euro at cruise running 90mph at 3000 Rs (4th gear) was getting about 17-18mpg on the last trip I took over to Melbourne from Orlando. That's about 90 miles each way.

125shifter

I tried cruising in my 930 once, it didn't work. Boost is just too adicting. I got about 10mpg before my never ending rebuild project started. I'm hoping for 15mpg when I'm done. If I can drive the car about 100,000 miles a year with current fuel costs my cost justification should work out.