Head Porting for Fuel Milage

General engine tech -- Drag Racing to Circle Track

Moderator: Team

PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Head Porting for Fuel Milage

Post by PackardV8 »

RDY4WAR wrote: Tue Jan 31, 2023 9:37 am The cost becomes a factor in all of this. I have a friend who used to be into the ecomodding. He said he tallied up all he had spent on mods to improve fuel economy, and he never broke even on the fuel cost saved. . . .
It's counter-productive.
It's also counter-productive to friendships to rub folks noses in the proof of their bad logic. I learned this in the first gas crisis in 1974. A friend had a paid-for Chrysler; when gas went from .35 to .55 a gallon, "Gotta get rid of this gas hog; it's eating me out of house and home!" He took it in the shorts on a trade-in, paid a premium for a VW diesel. He was so proud of it, "Gets 35 MPG." I said, "Let's do the numbers." Result was it would take seven years to pay for the VW and during that time he'd be driving a slow, noisy, smelly little manual transmission shitebox instead of his big, comfy Chrysler. When I pointed out all of this, he didn't speak to me for years.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Wetflow
New Member
New Member
Posts: 49
Joined: Wed Jul 20, 2022 11:22 pm
Location: Ormond Beach, FL

Re: Head Porting for Fuel Milage

Post by Wetflow »

PackardV8 wrote: Tue Jan 31, 2023 12:07 pm It's also counter-productive to friendships to rub folks noses in the proof of their bad logic. I learned this in the first gas crisis in 1974. A friend had a paid-for Chrysler; when gas went from .35 to .55 a gallon, "Gotta get rid of this gas hog; it's eating me out of house and home!" He took it in the shorts on a trade-in, paid a premium for a VW diesel. He was so proud of it, "Gets 35 MPG." I said, "Let's do the numbers." Result was it would take seven years to pay for the VW and during that time he'd be driving a slow, noisy, smelly little manual transmission shitebox instead of his big, comfy Chrysler. When I pointed out all of this, he didn't speak to me for years.
If a guy can't find the benefit of good logic, even after the fact, from a "friend" then he is not really a friend. A friend would have said something like " Thanks for pointing this out. I guess I screwed the pooch this time. At least you've taught me to look at cost-benefit analysis before making an investment. Let me buy you a beer".
BobbyB
Pro
Pro
Posts: 489
Joined: Mon Apr 15, 2013 1:35 pm
Location:

Re: Head Porting for Fuel Milage

Post by BobbyB »

PackardV8 wrote: Tue Jan 31, 2023 12:07 pm
RDY4WAR wrote: Tue Jan 31, 2023 9:37 am The cost becomes a factor in all of this. I have a friend who used to be into the ecomodding. He said he tallied up all he had spent on mods to improve fuel economy, and he never broke even on the fuel cost saved. . . .
It's counter-productive.
It's also counter-productive to friendships to rub folks noses in the proof of their bad logic. I learned this in the first gas crisis in 1974. A friend had a paid-for Chrysler; when gas went from .35 to .55 a gallon, "Gotta get rid of this gas hog; it's eating me out of house and home!" He took it in the shorts on a trade-in, paid a premium for a VW diesel. He was so proud of it, "Gets 35 MPG." I said, "Let's do the numbers." Result was it would take seven years to pay for the VW and during that time he'd be driving a slow, noisy, smelly little manual transmission shitebox instead of his big, comfy Chrysler. When I pointed out all of this, he didn't speak to me for years.
Well, let's do just a little figuring...

1983 Ranger XLT with all aptions 4x4 manual... $10,700.00 (as I recall)... 48 EASY payments of $254.00 per month... after trading in a danged good 1976 old omega!

about 40 years & 550,000 miles later... umh... 550,000 miles/17.5 miles per gallon...umh 31,429 gallons of 87 octane ...umh... lets not do any more cost figuring right now...umh... I like my old truck...

My newer truck only gets the same milage, but is twice a big, & has leather, and a CD player, & i will never live long enough to to wear either truck out.

Do you really believe that over 15,000 gallons of gas has passed through each of the original main carb jets in that old thing? Probably not... the transfer slot flow makes that calculation suspect.
RDY4WAR
Expert
Expert
Posts: 516
Joined: Tue Jun 20, 2017 12:58 am
Location:

Re: Head Porting for Fuel Milage

Post by RDY4WAR »

I still drive a '91 Nissan D21 hardbody with 482k miles on the KA24E with original timing parts. I starts right up and goes A-B reliably just like a new car would.
digger
Guru
Guru
Posts: 2722
Joined: Sun Jan 27, 2008 6:39 am
Location:

Re: Head Porting for Fuel Milage

Post by digger »

swirl
BobbyB
Pro
Pro
Posts: 489
Joined: Mon Apr 15, 2013 1:35 pm
Location:

Re: Head Porting for Fuel Milage

Post by BobbyB »

Measured last night:
Combustion chamber volume= 49 cc
Piston in hole=.087
Bore=3.700
Head gasket .045 thick x 3.73
current compression ratio= 7.49 to 1

Decking block .010 gives 7.65 to 1, .020 gives 7.82, .030 gives 8.00 to 1
mag2555
Guru
Guru
Posts: 4584
Joined: Sun Sep 18, 2011 11:31 am
Location: Heading for a bang up with Andromeda as we all are.

Re: Head Porting for Fuel Milage

Post by mag2555 »

Gez!
.132" in the hole is pretty bad.
From my experience if you can't do things that will get you at least a 1/4 of a point increase in compression then the effort involved is just not worth it.
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
BobbyB
Pro
Pro
Posts: 489
Joined: Mon Apr 15, 2013 1:35 pm
Location:

Re: Head Porting for Fuel Milage

Post by BobbyB »

mag2555 wrote: Thu Feb 02, 2023 11:43 am Gez!
.132" in the hole is pretty bad.
From my experience if you can't do things that will get you at least a 1/4 of a point increase in compression then the effort involved is just not worth it.
I know! I have heard that some rebuilder pistons have reduced compression height to compensate for increase compression ratio from overboring a block. I don't have the pistons out yet to check them though.

This 2.8 has a goofy chamber. It is a shallow bathtub with not much valve angle.
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: Head Porting for Fuel Milage

Post by PackardV8 »

BobbyB wrote: Thu Feb 02, 2023 12:24 pm
mag2555 wrote: Thu Feb 02, 2023 11:43 am Gez!
.132" in the hole is pretty bad.
From my experience if you can't do things that will get you at least a 1/4 of a point increase in compression then the effort involved is just not worth it.
I know! I have heard that some rebuilder pistons have reduced compression height to compensate for increase compression ratio from overboring a block. I don't have the pistons out yet to check them though.

This 2.8 has a goofy chamber. It is a shallow bathtub with not much valve angle.
All regular cast 2.8 rebuilder pistons in our experience are destroked .010" - .020". The good news is some hypereutectic pistons are not destroked. Read the specs carefully.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
BobbyB
Pro
Pro
Posts: 489
Joined: Mon Apr 15, 2013 1:35 pm
Location:

Re: Head Porting for Fuel Milage

Post by BobbyB »

Tom68 wrote: Sat Jan 28, 2023 4:21 pm
BobbyB wrote: Sat Jan 28, 2023 8:22 am No, I did not realize the objectives are in conflict. Explain more please.
Tom68 wrote: Fri Jan 27, 2023 4:27 am If you have high torque at cruise RPM you'll be running at high vacuum, good for fuel atomisation, bad for economy.

You can get the fuel atomisation with manifold heat and sharp edges on the valves and seats and your peak torque needs to be above your cruise rpm so there is less pumping loss.
If you do build a low rpm high torque engine, EGR could be used to reduce pumping losses.
How can I control the EGR valve to improve mileage if I eliminate the computer?
For what it is worth, with every high mileage 2.8 I have torn down has the EGR passages were completely clogged.
User avatar
Tom68
HotPass
HotPass
Posts: 2541
Joined: Mon Feb 07, 2022 3:43 am
Location: VIC OZ

Re: Head Porting for Fuel Milage

Post by Tom68 »

BobbyB wrote: Sat Mar 11, 2023 5:54 am
Tom68 wrote: Sat Jan 28, 2023 4:21 pm
BobbyB wrote: Sat Jan 28, 2023 8:22 am No, I did not realize the objectives are in conflict. Explain more please.
Tom68 wrote: Fri Jan 27, 2023 4:27 am If you have high torque at cruise RPM you'll be running at high vacuum, good for fuel atomisation, bad for economy.

You can get the fuel atomisation with manifold heat and sharp edges on the valves and seats and your peak torque needs to be above your cruise rpm so there is less pumping loss.
If you do build a low rpm high torque engine, EGR could be used to reduce pumping losses.
How can I control the EGR valve to improve mileage if I eliminate the computer?
For what it is worth, with every high mileage 2.8 I have torn down has the EGR passages were completely clogged.
Yer, probably not in a useful way, I clogged mine on a Buick/Holden v6 with a cut off 9/16 bolt shank, I'd like the little bit more economy but it had an acceleration hesitation that blocking it fixed. About to turn over 500,000 km, put heads on it when it did a head gasket, otherwise untouched.

20230311_220202.jpg
You do not have the required permissions to view the files attached to this post.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
User avatar
frnkeore
Expert
Expert
Posts: 825
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: Head Porting for Fuel Milage

Post by frnkeore »

RDY4WAR wrote: Tue Jan 31, 2023 2:20 pm I still drive a '91 Nissan D21 hardbody with 482k miles on the KA24E with original timing parts. I starts right up and goes A-B reliably just like a new car would.
Have you replaced or welded the timing cover?

My KA24E (240SX), timing chain, wore threw the timing cover @ ~200,000 miles. I have a core engine that has chain marks on the cover but, don't know the mileage.
RDY4WAR
Expert
Expert
Posts: 516
Joined: Tue Jun 20, 2017 12:58 am
Location:

Re: Head Porting for Fuel Milage

Post by RDY4WAR »

frnkeore wrote: Sat Mar 11, 2023 3:23 pm
RDY4WAR wrote: Tue Jan 31, 2023 2:20 pm I still drive a '91 Nissan D21 hardbody with 482k miles on the KA24E with original timing parts. I starts right up and goes A-B reliably just like a new car would.
Have you replaced or welded the timing cover?

My KA24E (240SX), timing chain, wore threw the timing cover @ ~200,000 miles. I have a core engine that has chain marks on the cover but, don't know the mileage.
The timing cover has never been off.
BobbyB
Pro
Pro
Posts: 489
Joined: Mon Apr 15, 2013 1:35 pm
Location:

Re: Head Porting for Fuel Milage

Post by BobbyB »

What valve job angles are best for low speed torque and fuel milage, given a almost verticle valve in a shallow bathtub chamber with 45 degree seats?
GARY C
HotPass
HotPass
Posts: 6301
Joined: Tue May 14, 2013 10:58 pm
Location:

Re: Head Porting for Fuel Milage

Post by GARY C »

Has anyone ever increased air inlet via cam and head flow and used less fuel?
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Post Reply