My 1991 Talon TSi Compound Turbo AWD

[BabyDiesel]

Russell, could you possibly drive 55 on your next tank? I want to see you break 80 mpg

[pgfpro]

Originally Posted by BabyDiesel

Russell, could you possibly drive 55 on your next tank? I want to see you break 80 mpg

That would be awesome but I don't think it will do it. For some reason 60mph is the cars most efficient mph??? I think it has to do to the very large intake ports and intake runners? I think it needs the velocity to work with the ultra lean burn?

Anyway I did some race fuel testing today and blew off two charge pipes back to back. I re-beaded them and they should hold to 55 psi.
Here is one of my home made tools for doing boost leak testing.

Good old can of tuna works every time.lol

[jedi_sol]

Proper DIY

[serialk11r]

Originally Posted by pgfpro

That would be awesome but I don't think it will do it. For some reason 60mph is the cars most efficient mph??? I think it has to do to the very large intake ports and intake runners? I think it needs the velocity to work with the ultra lean burn?

Definitely possible. Running the engine slowly and at low load works great on tiny economy engines with low valve lift, but for engines with greater "breathing" capability combustion efficiency can be a serious problem.

Porsche said that they were able to decrease idle fuel consumption by 20% when they moved from fixed cam profiles to Variocam Plus, and that was with low duration cams (high pumping losses).

My own FR-S has this problem too, below 2000rpm the efficiency drops like a rock. I can drive at 50mph and get 48mpg, or I can do 60 and get 42mpg. Even dropping the speed to 40mph, I can't really break 50ish. If I'm going 35mph, dropping down to 5th gear and 2000rpm engine speed vs. 1500rpm in 6th doesn't even drop the mpg by 10%.

Increasing cam overlap by just 5 degrees to introduce a little bit of EGR past what it was designed for from the factory caused some misfiring and a massive drop in fuel efficiency.

I imagine on your older engine, the engine could be struggling to burn the mix quickly at low speed.

[RustyLugNut]

Originally Posted by pgfpro

Good old can of tuna works every time.lol

. . . was it a dolphin safe can of tuna?

[pgfpro]

Originally Posted by serialk11r

Definitely possible. Running the engine slowly and at low load works great on tiny economy engines with low valve lift, but for engines with greater "breathing" capability combustion efficiency can be a serious problem.

Porsche said that they were able to decrease idle fuel consumption by 20% when they moved from fixed cam profiles to Variocam Plus, and that was with low duration cams (high pumping losses).

My own FR-S has this problem too, below 2000rpm the efficiency drops like a rock. I can drive at 50mph and get 48mpg, or I can do 60 and get 42mpg. Even dropping the speed to 40mph, I can't really break 50ish. If I'm going 35mph, dropping down to 5th gear and 2000rpm engine speed vs. 1500rpm in 6th doesn't even drop the mpg by 10%.

Increasing cam overlap by just 5 degrees to introduce a little bit of EGR past what it was designed for from the factory caused some misfiring and a massive drop in fuel efficiency.

I imagine on your older engine, the engine could be struggling to burn the mix quickly at low speed.

That is a very good point!!! Something that isn't talked to much about.

I wish my cams weren't fixed. I tried to find a cam profile that would be give me the high rpm flow with low overlap for FE. After doing some WOT pulls the engine lays down around 6000 rpm. This is making me run a much higher octane full more then I wanted to at WOT high boost and WOT mid boost pump gas only do to my low rpm shift points dropping from 6500 rpm to 4400 rpm. This will get better with cooler ambient temperature as Fall approaches but it still drives me crazy. So I'm going to see what the cooler temps bring.
Trying to make awesome power and still get great fuel mileage is a major pain and has been a lot harder then I would have ever thought.

[pgfpro]

Originally Posted by RustyLugNut

. . . was it a dolphin safe can of tuna?

After looking at the can more closely I don't think it is. I need to make a run to the store and find me a dolphin safe can with the same diameter as this one.

[pgfpro]

Well this car isn't all fun and games. Yesterday it left me stranded about 3 miles from my house. Lucky I was watching my new Steam 7 as much as possible while driven in town and noticed the battery voltage was dropping. So I went straight back home with all the short cuts I could think of. At 8.8 volts she started popping and stuttering. Luckily I made it into a church parking lot, thank the lord.lol Me being a cheap person when the engine was all torn down I should have replaced the alternator, but didn't. So about an hour later I finally got the alternator out.

This got me thinking since these 90's Talons are known for having a week alternator and I'm taxing the system with two fuel pumps running and my Tilton oil return pump, plus now my vacuum pump and sometimes the radiator fan. I need to come up with a better plan. So I'm going to put the secondary fuel pump on a switch and use as needed, and have the vacuum pump come on with a switch also when needed which is usually to launch the car from a stand still and at freeway speed I can cycle it when I start loosing brake booster vacuum. Plus at freeway speed the radiator fan won't come on so this will give the system some time to charge the battery.

I'm also going to start using engine braking in stop and go traffic to help with the charging system. Some thing I never thought of until now.

Well its been a fun few days fixing blown off charge pipes and vacuum lines and now an alternator. But I guess you have to take the good with the bad. lol

[pgfpro]

Update:

I install the new alternator but to do this you have to remove the drivers side engine mount. This is what I found.

So a new one cost $160.00 so what I did is what I've done in the past and repaired the mount with 3M 8609 windshield Urethane.

Out side curing.

So tomorrow I will install it, and get back to testing and tuning.
I have had great luck with this in the past. They make aftermarket Urethane mounts but I don't like the vibration they cause. This is a little more driver friendly.

[RobertISaar]

window weld is still super stiff in comparison to the stock rubber, but actual poly inserts are just... harsh in operation with every vehicle I've been in that used them.