Turbocharging? Vacuum? Too much thinking. Smart people unite

[oil pan 4]

Is 45mpg for that Honda turbo real world numbers or EPA imaginary numbers?

If some one make a 1.5L, direct injection, variable cam timing engine it better get good fuel economy.
By any chance is there a comparable 1.5L non turbo, DI, variable cam engine to compare to?

[pgfpro]

I have already did testing on this with my 1991 AWD Turbo Talon.

0" Hg to .5lbs boost I run my IAT temps at 200+*F.
My lean-burn A/F ratio is around 33:1 with my home made stratified charge pre chamber.
4.36 lbs/min of air
0.132 lbs/min of fuel
All the above numbers are at 2390 RPM
41 mpg at 55 mph
Drive pressure is around 1psi.
I'm also running a hot air system and modified lifters for single valve operation
to promote swirl.

It can be done but it takes a lot of extra modifications to make it work.

[oil pan 4]

If you're getting 41mpg at 55mph during sustained speed driving with extreme lean burn then I doubt that honda gets over 40mpg real world.

[Wiegraf]

Originally Posted by oil pan 4

Is 45mpg for that Honda turbo real world numbers or EPA imaginary numbers?

If some one make a 1.5L, direct injection, variable cam timing engine it better get good fuel economy.
By any chance is there a comparable 1.5L non turbo, DI, variable cam engine to compare to?

I understand and this is the problem. No real world examples unless I/We do it.

Thats why I didn't use the Earth Dreams as an example. Meh.. Ithink I've got my answers.

[pgfpro]

Originally Posted by Wiegraf

On 2 identical motors.. one n/a , one turbocharged.

Cruising at or closer to 0 inHg
Vs
as much vacuum as possible....

which is better for MPG?
I know cruising closer to 0 inHg is counter to what is efficient.

My thinking is while cruising at

(Example incoming)

2 60mph at 2000 rpm in N/A car at 16inHg (or whatever a vx cruises at)
Or
60mph at 2000 rpm in Turbo Car at 0 inHg/PSI ( give or take 1 or 2 in either direction psi or inHg)

The turbo car has more loss in Mechanical Efficiency (ME) from driving turbine wheel (albeit small) and Thermal Efficiency (TE) but it is also using free wasted energy (in the form of Hot exhaust gases) to spool turbine to Force more air into a cylinder thus increasing Volumetric Efficiency (VE). Also at closer to 0 inHg/PSI there is less pumping losses associated....

This is alll just early-morning-drive-to-work thinking....anyone want to chime in.


Also to add.. this was originally posted on my Facebook and the loss and thermal efficiency was a problem because I was referring to normal car and heat soak. However in the interest of this form a lot of people use a warm air intake so I'm wondering if the thermal efficiency will actually be a benefit as far as this conversation

To make this work you have to lean out the engine and increase the IAT temps drastically.
Example a 1.5L at
2000RPM
16.29 hg
70 IAT
14.7 A/F
BSFC .50
will make round 14.5HP

If we drop it to 0"HG it will now make 32.2 HP with the same BSFC. Actually the BSFC will get better but for now we will keep it the same. 32 HP is to much for light load cruising and the car will accelerate. So we need to lower the amount of air. So lets start with a much higher IAT at a 14.7 A/F ratio.
150*F = 27.9 HP
200*F = 25.8 HP
250*F = 24.0 HP
300*F = 22.4 HP
As you can see we need to also lean out the A/F ratio to get back to 14.5
150*F = 27.9 HP plus 29:1 A/F = 14.2 HP
200*F = 25.8 HP plus 26:1 A/F = 14.6 HP
250*F = 24.0 HP plus 24:1 A/F = 14.7 HP
300*F = 22.4 HP plus 23:1 A/F = 14.3 HP

Now this is just a example but it shows you need to lower the amount of
air lbs/min to make it work.

[Wiegraf]

Originally Posted by pgfpro

To make this work you have to lean out the engine and increase the IAT temps drastically.
Example a 1.5L at
2000RPM
16.29 hg
70 IAT
14.7 A/F
BSFC .50
will make round 14.5HP

If we drop it to 0"HG it will now make 32.2 HP with the same BSFC. Actually the BSFC will get better but for now we will keep it the same. 32 HP is to much for light load cruising and the car will accelerate. So we need to lower the amount of air. So lets start with a much higher IAT at a 14.7 A/F ratio.
150*F = 27.9 HP
200*F = 25.8 HP
250*F = 24.0 HP
300*F = 22.4 HP
As you can see we need to also lean out the A/F ratio to get back to 14.5
150*F = 27.9 HP plus 29:1 A/F = 14.2 HP
200*F = 25.8 HP plus 26:1 A/F = 14.6 HP
250*F = 24.0 HP plus 24:1 A/F = 14.7 HP
300*F = 22.4 HP plus 23:1 A/F = 14.3 HP

Now this is just a example but it shows you need to lower the amount of
air lbs/min to make it work.

Literally all i needed from tbe get go... now... curious what about.... both cars at same inHg.
Just for my last curiousity. Will the BSFC help?

Both cars cruising at 16.29 inHg.

Thank you again for bringing it to me Barney style.

[pgfpro]

Originally Posted by Wiegraf

Literally all i needed from tbe get go... now... curious what about.... both cars at same inHg.
Just for my last curiousity. Will the BSFC help?

Both cars cruising at 16.29 inHg.

Thank you again for bringing it to me Barney style.

If I understand you correctly both cars at 16.29 Hg. which one will be more efficient? If the compression ratio is the same and the cam profiles are the same both will have similar efficiency, but that's not the case in the OEM market with a petrol engine the turbo cars engine will have a lower CR and turbo cam profiles that will make a higher numeric BSFC number.

[Wiegraf]

Originally Posted by pgfpro

If I understand you correctly both cars at 16.29 Hg. which one will be more efficient? If the compression ratio is the same and the cam profiles are the same both will have similar efficiency, but that's not the case in the OEM market with a petrol engine the turbo cars engine will have a lower CR and turbo cam profiles that will make a higher numeric BSFC number.

I know.. a d15z1 .... 2 identical.

One with a small little turbo

One not.

Cruising next to each other. Does that help.

[Baltothewolf]

Originally Posted by oil pan 4

Is 45mpg for that Honda turbo real world numbers or EPA imaginary numbers?

If some one make a 1.5L, direct injection, variable cam timing engine it better get good fuel economy.
By any chance is there a comparable 1.5L non turbo, DI, variable cam engine to compare to?

Real world numbers. When I had my 2016 (which wasn't even broken in yet) I got 45mpg round trip consistently at 70mph (cruise set at 70). With the A/C on, I got 41-43.

If I boosted my Miata, I wouldn't be aiming for increased efficiency. I would be going for power. But turbo Miatas get better MPG freeway because (for those who do it right) run MS and can play with the timing/other things that increase highway MPG.

[pgfpro]

Originally Posted by Wiegraf

I know.. a d15z1 .... 2 identical.

One with a small little turbo

One not.

Cruising next to each other. Does that help.

Actually I did this on a 1.5 D15 on my sons car. We installed a turbo kit and ran it for a week or two with a stock ecu. I told my son don't boost it until I tuned it on CROME. The car got the same fuel mileage as it did before. Infact it increased the mileage by 2 mpg but this could of been my son driven it more efficient.