TDI variant Questions

[mn_vette]

I am excited about the plans Dave has for a coupe body that can withstand the elements and get a great fuel economy to boot. And while that may be its original intent I was wondering what kind of performance it would have. Obviously the chassis will be up to the task, but what about the engine. Since I haven't seen alot about the actual engine/technology set up that gets the great fuel economy I'm not really sure what can be done.

Will we be able to put a larger turbo and run a boost controller for track days? Or maybe just a new ECU flash to change the programming? The coupe will have low drag aerodynamics so maybe we can have a few adjustable air lips to get some downforce and then you are ready for track day?

The best of both worlds would be great but if its not possible hopefully the WRX engine setup will fit in the coupe body without any issues.

[Niburu]

most of what you asked about will be up to you, the builder of said car

[mn_vette]

most of what you asked about will be up to you, the builder of said car

That is only the case IF it is compatable with the high mileage technology that would be going with the TDI engine. I haven't seen a list of modifications that need to be done to the engine to get the better fuel economy. They could be doing some very interesting things that may limit or enhance the power output.

[Xusia]

I could be wrong, but I believe they are expecting the TDI to achieve the high mileage goals in stock form. Keep in mind the 818 will weigh far less than the VWs the TDI engine is typically found in. It wouldn't surprise me if the 818 also had better aerodynamics. I would expect these factors to positively impact gas mileage even without engine modifications.

[skullandbones]

I think this is an interesting question because performance vs mpg has always been sort of incompatible. I like the Camaro V6 with 305 hp and 28 mpg. You haven't seen a lot of that until recently. I had a 396 with a tunnel ram manifold and 2 Qudrajet 625 carbs that made 15 mpg on the highway because of the type of carbs (small primary and giant secondary) and progressive linkage. It also go almost no mpg if you dumped the trottle. But the bottom line is that it's really up to the builder to determine how extreme the engine performs. I think a turbo version with multiple mappings would be very adaptable. WEK.

[err0r]

You should check out tdiclub.com for information on TDI stuff. Some of the guys there are running 200+whp with 350lbs torque. I get ~45MPG and I have an upgraded turbo, ecu (stage 4 @ 25PSI) and injectors (~160hp) in my Golf as a daily driver with 225k miles. So much torque makes it really fun to drive. I drive with my foot in it constantly, get great mileage and that's with a heavier car. I get about the same fuel mileage now as I did before the modifications. Better if I baby it (who wants to do that).

All that said, I was planning on building one with the boxer engine. I already have a TDI I love and can drive every day.

[err0r]

*double post*

[Draco-REX]

Weight is the enemy of all.

Chew on this: In 1980 the Honda Civic was rated at 55mpg. That's a gas engine.

What happened? It got heavy.

So take a diesel that can sip fuel and put it in a lightweight body with better aero and you'll have a very fuel efficient car with no modifications to the engine.

[Xusia]

In 1980 the Honda Civic was rated at 55mpg. That's a gas engine.

Are you sure about this? I know the Civic CRX HF model (NOT the regular CRX, and yes the CRX was originally a variant of the Civic and not it's own model...) was rated at 55mpg, but not the regular Civic, and not in 1980 (at least as far as I know).

[err0r]

What I'm saying is, you can mod and drive the hell out of the diesel engine and still get the same if not better fuel mileage.

[Draco-REX]

Are you sure about this? I know the Civic CRX HF model (NOT the regular CRX, and yes the CRX was originally a variant of the Civic and not it's own model...) was rated at 55mpg, but not the regular Civic, and not in 1980 (at least as far as I know).

Maybe it was the HF, but even the regular civic was 49mpg highway.
http://www.adclassix.com/a5/80hondacivic.html

[Oppenheimer]

I think Dave mentioned the mpg version would use west philly high green gran prix winning technology. That implies there would be engine mods to achieve the very high mileage goals.

But that doesn't mean you have to do those mods. My guess is there will be a balance point between performance and economy. You can some of Daves recommended economy mods and some performance mods to find your own ideal balance.

[Xusia]

Maybe it was the HF, but even the regular civic was 49mpg highway.
http://www.adclassix.com/a5/80hondacivic.html

Wow. I never knew that and would never have guessed. That's amazing. Based on the Civic CRX HF, I've always wondered why people consider 30mpg "good" these days, but that really makes wonder "WTF is everyone thinking?!?" If they could do 49mpg back in 1980 off a regular old gas engine, why can't we do better today?!?

[Steve91T]

If you could get close to 200 hp out of the TDI and keep it reliable, that would be a killer set up. A lot of people still think that diesels are boring. Has anyone driven the BMW 335d? You wouldn't guess that it's a diesel. Amazing throttle response, more torque than any gas engine I've driven, and gets 36 MPG easily with a 5K redline.

My 99 F250 Powerstroke has nothing more than an intake, exhaust, and a mild tune. I've got 300 hp and 600 ft/lbs to tq to the ground. The truck weighs somewhere around 7500 lbs and I get 18 MPG around town, and 20 on the highway.

I think it'd be fun to build the 818 with the TDI. I would love to see the look on people's face when I pass them with my TDI on the race track.

[Draco-REX]

Wow. I never knew that and would never have guessed. That's amazing. Based on the Civic CRX HF, I've always wondered why people consider 30mpg "good" these days, but that really makes wonder "WTF is everyone thinking?!?" If they could do 49mpg back in 1980 off a regular old gas engine, why can't we do better today?!?

Weight.

[Oppenheimer]

My '89 CRX HF got 50-ish mpg (mix hwy/city). No matter how hard I drove it, I never got less than 40-something mpg. I used to thrash that thing. It had surprisingly good torque, and wasn't gasping at the upper end of the tach either. It only weighed I think 1400 lbs or so, so it didn't take much motor to feel lively, and it was nimble too, even with its skinny, low rolling resistance tires. It had that funky, aero shape.

Nimble around town, OK on the on-ramp, but a bit gutless at hwy speed. But it was fun to drive. Wish I still had it. Wish they still made cars like that. Imagine what a car like that, with modern engine tech, would get for mpg? That is what the 818 TDi will be, except with a race car chassis, better brakes and suspension, a few more lbs, but a better power/weight ratio, and better looks (though Dan F will probably like the CRX looks better).

[mn_vette]

Wow. I never knew that and would never have guessed. That's amazing. Based on the Civic CRX HF, I've always wondered why people consider 30mpg "good" these days, but that really makes wonder "WTF is everyone thinking?!?" If they could do 49mpg back in 1980 off a regular old gas engine, why can't we do better today?!?

The weight definately plays a big factor in the reduction of the fuel economy. The added weight goes hand in hand with the newer saftey requirements. The Government wants us to be safe when we crash. Then they start mandating that cars have better fuel economy while being safer and they don't expect the prices to go up at all. Aren't politicians great.

[Draco-REX]

The weight definately plays a big factor in the reduction of the fuel economy. The added weight goes hand in hand with the newer saftey requirements. The Government wants us to be safe when we crash. Then they start mandating that cars have better fuel economy while being safer and they don't expect the prices to go up at all. Aren't politicians great.

Yup. The EPA wants everyone riding bicycles while the NHTSA wants everyone driving tanks. And it doesn't help that the average american car consumer wants a 3 ton, 8ft high, 25ft long car to do everything for them including telling them where to go while they sit on a cooled butt massager and drink from a mug heated by the cup holder with a cell phone in one ear so they can complain about over-congested highways and how much they have to pay at the gas pump.

Makes me sick.

[Xusia]

Yup. The EPA wants everyone riding bicycles while the NHTSA wants everyone driving tanks. And it doesn't help that the average american car consumer wants a 3 ton, 8ft high, 25ft long car to do everything for them including telling them where to go while they sit on a cooled butt massager and drink from a mug heated by the cup holder with a cell phone in one ear so they can complain about over-congested highways and how much they have to pay at the gas pump.

Makes me sick.

ROFLMAO! Now THAT was funny! (partly because there is a measure of truth to it)