Inertia vs aero drag vs rolling resistance in urban and highway driving

[Logic]

Swiss Cheese Porsche 911:
1000 to 595 kg. No economy numbers.



https://www.drivencarguide.co.nz/new...ety-nightmare/

[Logic]

"...A recent study estimates that vehicle weight reductions of 35% could be implemented at
reasonable cost...
Vehicle weight reductions of this magnitude could reduce fuel consumption by 12 to 20% with no sacrifice in current vehicle safety and performance attributes...

...for every 100-kg reduction, the combined city/highway fuel consumption could decrease by about 0.4 L/100 km for cars and about 0.5 L/100 km for light trucks..."
https://natural-resources.canada.ca/...sheet_16_e.pdf

NB that's for combined city and highway.

[Logic]

Vehicle Lightening: Shaving Pounds Saves Gallons

...if automakers could lighten their vehicles by 20%, fuel mileage might improve by as much as 16%.
So a vehicle of 3500 lbs. that currently gets 30 miles to the gallon would become a 2800-lb. vehicle that could get an extra 5 mpg...

...the U.S. Environmental Protection Agency and conducted by the FEV Corp. dissected a Toyota Venza and showed how 750 lbs. could be removed from the vehicle without affecting its performance. Better yet, the weight-reduced vehicle in their study actually cost $150 less to make...
https://www.motor.com/magazine-summa...s-maybe-cents/

Any aero mods here saving ~16% in city (98% of) driving..?

[Logic]

Lightweighting Impacts on Fuel Economy, Cost, and Component Losses
I've only scanned the document, but they look at a conventional vehicle, HEV, PHEV and EV, with lots of pretty graphs.
https://www.nrel.gov/docs/fy13osti/57607.pdf

[freebeard]

From the motor.com article:

www.greencarcongress.com: GM develops integrated exhaust manifold cylinder head for 3.6L V6 direct injection engine; improvement in performance, fuel economy, emissions and noise


The reduced complexity of the design of the new integrated exhaust manifold cylinder head (bottom) compared to the old (top)

My 1959 Nash Rambler had the exhaust pipe strapped to the side of the block and the carburetor was boxed onto the flat head.


https://www.macsmotorcitygarage.com/...9-Nash-600.jpg

[Logic]

Looking at:
How to drill drill out or hollow bolts.
and
'Where to buy' hollow (drilled) bolts.

It looks like people are happy to 'Get Technical' about it with talk of hollow bolts being 'Stronger' and maths on the subject. Hole vs shank diameters etc-etc!

Then there's talk on 'Where to Buy' Hollow Bolts and Aluminum Bolts and even Hollow Titanium Bolts!

So this is just a bunch of links to forums discussing the 'how to's and maths and 'where to buy's, for now:
https://www.gt40s.com/threads/source...t-bolts.38380/
https://www.practicalmachinist.com/f...uminum.365860/
https://www.accessnorton.com/NortonC...d-axles.14507/


The overlap with racing is noteworthy.
ie: If you want to make an Eco Car;
Talk to and copy the racing guys 1st; DO what they do, then just drive 'Eco' rather than 'race'.

Well... until a nice twisty, quiet bit of tarmac presents itself!
There is more (fun) to life than just 'Eco'!

[Logic]

Originally Posted by freebeard

From the motor.com article:

www.greencarcongress.com: GM develops integrated exhaust manifold cylinder head for 3.6L V6 direct injection engine; improvement in performance, fuel economy, emissions and noise


The reduced complexity of the design of the new integrated exhaust manifold cylinder head (bottom) compared to the old (top)

My 1959 Nash Rambler had the exhaust pipe strapped to the side of the block and the carburetor was boxed onto the flat head.


I searched:



https://www.macsmotorcitygarage.com/...9-Nash-600.jpg

Intake (Air) volume is around 1/4 of exhaust gas volume IIRC and that's all due to the much higher temperature of the exhaust gas.

IMHO, if you do NOT have a Tuned Length 'Banana Branch' Exhaust; cooling the exhaust gasses means way less gas volume 'trying to escape' and THAT means less energy wasted by the engine having to 'push' it out.

ie: Heads (with built in manifolds) that cool the exhaust to the cooling system see this benefit.

I recall reading about some race class where you had to use the stock engine manifold and exhaust.
Someone enclosed the stock manifold in a water jacket, cooled by the stock (upgraded?) cooling system and saw something like 10 to 15 extra kw from doing so!

There is said to be a noticeable decrease in exhaust noise too, all else being equal.

ie: I don't think integrating un-optimized manifold systems into the head is worth the weight savings..?
But they do benefit from the extra cooling vs a std, un-cooled, un-tuned-lenghth manifold.


(I did a quick search for:
Exhaust; cooling the exhaust gasses means way less gas volume 'trying to escape' and THAT means less energy wasted by the engine having to 'push' it out

This is what Google AI has to say (with links):

AI Overview

Yes, cooling exhaust gases reduces their volume and, therefore, the amount of energy needed to expel them, potentially improving engine efficiency.

Here's a more detailed explanation:

Cooling and Volume:
When gases cool, they contract, meaning they occupy less space. This is a fundamental principle of thermodynamics.

Reduced Energy Requirement:
An engine expels exhaust gases by creating a pressure difference between the cylinder and the exhaust system. If the exhaust gases are cooler and thus less voluminous, the engine doesn't need to work as hard to push them out, reducing energy waste.

Exhaust Gas Recirculation (EGR):
Some engines use cooled exhaust gas recirculation (EGR) to reduce NOx emissions and improve fuel efficiency. By recirculating a portion of the exhaust gases back into the intake, the combustion temperature is lowered, which in turn reduces NOx formation.

Waste Heat Recovery:
Cooling exhaust gases can also allow for waste heat recovery. The heat energy in the exhaust can be used to heat the engine coolant, warm the cabin, or generate electricity, further improving overall efficiency.

Exhaust System Design:
The exhaust system plays a crucial role in managing the flow of exhaust gases and ensuring efficient removal. It includes components like the exhaust manifold, catalytic converter, muffler, and tailpipe, all designed to optimize gas flow and reduce backpressure.

ie: There is a lot to be said for a (finned?) copper pipe exhaust, from the Pressure Wave Termination Box back. IMHO

(NB that the various attempts at a a Pressure Wave Termination Box that come up in the above links have 'Got it wrong' IMHO:
The last 'Into 1' pipe length is also important in 'sucking' exhaust out of the engine and has been skipped (Pre BWTB) in all those V8 examples...)

[Logic]

From here:

freebeard:
I'd thought the deal was to drill out the centers of bolts.

19bonestock88:
if that werent so tedius id have done it on the Saturn, with every bolt i could reasonably get to...

Logic:
I would say that cutting off excess bolt length is easiest.
Followed by removing brackets and things for non existent bits.
(Brackets etc for kit that's on higher end models etc.)
Then drilling holes in (excessive) surfaces.

If you have a lathe with a 3 jaw chuck; drilling out bolts is a piece of cake:
Self centering..!
Trying to do so with a drill stand; I wouldn't even bother trying!
Easier to go buy hollow and/or Aluminum etc bolts.

(I wish this had occurred to me back when I was riding a 'Nifty 50' (cc motorbike).
A bigger % of total weight...
But back then, 'The wrong head' was running the show!

I'd center a nut or tapped hole in a plate once and then thread each bolt into it. Fast and repeatable.

freebeard:
I'd center a nut or tapped hole in a plate once and then thread each bolt into it. Fast and repeatable.

Logic:
With a bench drill; drill a hole in something, and 'tap in chuck', tap it and its centered!
Good plan!

freebeard:
That would be super accurate. Someone could make a Youtube video.

I wonder what % can be hogged out.

NEW:
Thx. That's A plan...
The big part of the milling machine is still here...

[Logic]

Comprehensive Guide to Hollow Bolts – Lightweight, Strong, and Versatile Fasteners
https://www.yzfastener.com/news/comp...ightweigh.html

Light weight nuts & bolts sources, Hollow and aluminum?
https://www.practicalmachinist.com/f...uminum.365860/

Edit:
GT40 Tech - Garages and Tools Hollow bolts
https://www.gt40s.com/threads/hollow-bolts.45358/

As they're open.


https://www.amazon.com/hollow-bolt/s?k=hollow+bolt

Bling hollow Bolts
https://neloscycles.com/Stems-Hollow-Bolt/

[19bonestock88]

Originally Posted by Logic

Swiss Cheese Porsche 911:
1000 to 595 kg. No economy numbers.



https://www.drivencarguide.co.nz/new...ety-nightmare/

this was literally the inspiration for the weight reduction build on my Saturn