Why EFI?, maybe excellence was expected and they came as close as they could.. Options

[Darren C]

If you compare the normalized curves, I'd guess one of the dynos was measuring off by ~225 rpm since the curves are nearly line-on-line with that shift. My guess is that the slope of the curve is different between yours and Geoff's because there is a slightly different driveline loss multiple (Cl) being applied. Given that, it does look like yours drops off sooner so there is probably some more carb tuning to be had.

Thanks jd74914, again great work on the data, and it makes complete sense with my gut feeling that the two Dyno traces had an inaccuracy somewhere in RPM.
I agree about a little more fine tuning on my particular car might be needed just to delay that drop off in curve at the end. That's why I'm hoping someone out there has a D-Jet stock AFR trace so I can see it's fueling. I'd guess I need to lean off my AFR post 4500RPM to get an exact matching D-jet curve (it isn't far off mind you already). But to be fair, I don't plan on sustained running at those RPM's. I have more of a classic car Sunday cruise plan for my 914, as I've got other big brutal monsters in my garage already that'll pass the 200mph mark and set my pants on fire, so don't need to prove anything with this 14. :-)

[brant]

You don't want to match a stock djet afr trace!

The actual fuel used today is a much different blend than the blend that cars were set up for by the factory

Whether it's a difference in fuel blend or the factory's tune for emissions and economy. The stock are trace is not ideal.

I retune my stock fuel injection for a more rich mixture and still get 31-32mpg on the highway (1974 2.0)

[Bleyseng]

I have another dyno chart somewhere and the AFR is pretty flat at 13.5 to one upto 5500rpms

[Darren C]

You don't want to match a stock djet afr trace!

The actual fuel used today is a much different blend than the blend that cars were set up for by the factory

Whether it's a difference in fuel blend or the factory's tune for emissions and economy. The stock are trace is not ideal.

I retune my stock fuel injection for a more rich mixture and still get 31-32mpg on the highway (1974 2.0)

Hi Brant, I think I didn't explain well or the meaning in my post is mis-understood. The D-Jet curve I'd like to match is the end of the HP curve, where it looks at the moment mines dropping off early. The AFR of the D-jet I'll never be able to match as the car would always want to run richer with carbs.
I'd like to see the AFR of a stock D-jet just for curiosity and to gain knowledge and understanding of the "benchmark" and also as a comparison to what happens to the AFR through the rev range when you fit carbs.
I agree totally that stock classic car engines (of all types) on modern fuels and with a good few miles under their belts often benefit from running a little richer than 40 years ago when they were new and running on older fuel types and blends.

Geoff,

If you have another graph with AFR trace that would be brilliant! Better to have your trace as it goes with the data you already posted so the best info we could have!
Thanks in advance

[euro911]

Hey fellas, what's the best oil for air-cooled motors? (IMG:style_emoticons/default/hide.gif)

(IMG:style_emoticons/default/laugh.gif)

[falcor75]

Hey fellas, what's the best oil for air-cooled motors? (IMG:style_emoticons/default/hide.gif)

(IMG:style_emoticons/default/laugh.gif)

Oh no you didnt.... (IMG:style_emoticons/default/WTF.gif)











(IMG:style_emoticons/default/biggrin.gif)

[brant]

Hey fellas, what's the best oil for air-cooled motors? (IMG:style_emoticons/default/hide.gif)

(IMG:style_emoticons/default/laugh.gif)

It depends on which tires you are running...

[veekry9]

And on the tenth page,they lost their minds.
(IMG:style_emoticons/default/tongue.gif)
(IMG:style_emoticons/default/wacko.gif)
(IMG:style_emoticons/default/prop.gif)
(IMG:style_emoticons/default/biggrin.gif)
/


(aircooledtechguy pix),T4 exhaust,section thru studs.

The beauty of the DFI is the lack of cylinder wall washing by raw fuel,improving ring life.
Drill and tap a hole into the chambers,preheat and tig weld the barrel from the chamber side.
Final drill and tap for the DFI injector,then,machine the head complete.
A dry flowing int port can be reshaped,without the unatomized fuel pooling out of suspension.
/

T4 intake,section thru valve guide and seat.


Good pix of the T4,T1 heads in sawn sections,as above.
http://www.thesamba.com/vw/forum/viewtopic.php?t=602256
Unlike the second plug proposal,a DFI install ought to enter the chamber from the intake,"fat"part of the chamber.
Could it be as good as 20HP/TQ across the graph?
/

[Chris H.]

Hey fellas, what's the best oil for air-cooled motors? (IMG:style_emoticons/default/hide.gif)

(IMG:style_emoticons/default/laugh.gif)

It depends on which tires you are running...

Brant can I run a 205 series tire under stock fenders? What size do you guys like? Hope this hasn't come up before.

[rhodyguy]

Maybe Chris. Depends on your wheels and the chassis. (IMG:style_emoticons/default/huh.gif) (IMG:style_emoticons/default/biggrin.gif)

[DBCooper]

Idiots!! [grumble, grumble] Use the gotdamm search function!!

Oh yeah, the horse! Gotta take out some of this hostility and abuse that poor long-suffering horse!! (IMG:style_emoticons/default/dead horse.gif)

[mbseto]

Since we are digressing...
Always thought the six-stroke engine concept would be cool to apply to an air-cooled engine:
http://autoweek.com/article/car-news/insid...x-stroke-engine

An additional set of strokes is added to inject water into the piston. It turns to steam from the stored heat of the piston, so it gives an extra power stroke while cooling the cylinder at the same time.

[rhodyguy]

Interesting article.

[veekry9]

The main crankshaft with one(of four) rod and piston. The power is taken off this crankshaft while the top crankshaft operates the small top pistons to give favourable port openings. (Cars and Drivers)

https://primotipo.com/tag/bob-chamberlain/
Well,this '40s engine type would now be a viable proposition with the DFI tech available today.
Swinging the twincrank to beyond 12K,with fuel efficiency never before possible.
A moment cancelling design,smooth.
(IMG:style_emoticons/default/smile.gif)
/

[Darren C]

Very interesting Veekry9,

While we're going off course a little...

I was an Engineer in the Navy for 18 years and one of our engine types was a Napier Deltic, I led teams rebuilding, replacing and maintaining them. They had opposing pistons and 3 cranks in a delta (triangle) layout.

https://en.wikipedia.org/wiki/Napier_Deltic

I also worked on an array of gas turbines, from full tear down and rebuilds to straight replacements, and general servicing. These included Early marinized Rolls-Royce aero engines, Tyne, Olympus (same engine as our Concord jet plane had) and Spey, I even qualified in the Harrier jump jet Pegasus too. We also used the Rover turbine (as a fire water pump) I rebuilt a few of these too. A very similar Rover BRM basic design copy engine was used in the Howmet race car.

https://www.youtube.com/watch?v=GAgLSy371us

I've actually help fix one of these gas turbine race cars in the paddock at Goodwood!

The complexity of the Fueling systems on these babies would blow your mind in comparison to D-jet :-)

[Bulldog9]

Hey fellas, what's the best oil for air-cooled motors? (IMG:style_emoticons/default/hide.gif)

(IMG:style_emoticons/default/laugh.gif)

The REAL question is "Why did they design an engine that needed oil?" Did they Eff that up too? (IMG:style_emoticons/default/drunk.gif)

[ClayPerrine]

[wes]

Hey fellas, what's the best oil for air-cooled motors? (IMG:style_emoticons/default/hide.gif)

(IMG:style_emoticons/default/laugh.gif)

The REAL question is "Why did they design an engine that needed oil?" Did they Eff that up too? (IMG:style_emoticons/default/drunk.gif)

Ah Oil is thicker than water!

[veekry9]

Yeah,the Moon had not yet been traveled to,and turbine and Wankel engines were going to be the next big thing.
Today,I would surmise the vast improvement in materials would make a turbine/electric/magnetic/hybrid car
a marketable space age set of wheels.Heck,you could run it on recycled cooking oil/kerosene/mdo.
A set of igniters in each cylinder,to initiate a more complete burn will likely be the next big improvement for piston engines.
High temperature magnesium,whodathunkit?I'd like to see the response a lightweight reciprocating mass as applied to the
aircooled engines would have.The crank could be lightened substantially,piston velocities near or beyond what F1 is attaining today.
Something old is new again,the Napier is a diesel in the marine application I would guess.
Diesel with solid state spark ignition,when was the last time that was tried,I wonder?
Mg:
Cost, pure: $3.7 per 100g.
Cost, bulk: $0.29 per 100g.

http://www.hotrod.com/how-to/engine/hrdp-1...t-vapor-engine/
https://www.google.ca/webhp?sourceid=chrome...+piston+engines
https://www.google.ca/webhp?sourceid=chrome...car+documentary
With the modern control of fuel by electronic means,EFI,the leanout of the chamber could be attained,a temp not possible then.

Appears you've had your sea legs for a lifetime.
Been to the Bay o' Biscay?(Cockney)
https://en.wikipedia.org/wiki/Rogue_wave
(IMG:style_emoticons/default/biggrin.gif)

[87m491]

Dupe post Never mind