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.
Head Porting for Fuel Milage
Moderator: Team
Re: Head Porting for Fuel Milage
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Studebaker-Packard V8 Limited
Obsolete Engineering
Re: Head Porting for Fuel Milage
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".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.
Re: Head Porting for Fuel Milage
Well, let's do just a little figuring...PackardV8 wrote: ↑Tue Jan 31, 2023 12:07 pmIt'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.
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.
Re: Head Porting for Fuel Milage
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.
Re: Head Porting for Fuel Milage
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
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
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Re: Head Porting for Fuel Milage
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.
.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!
Re: Head Porting for Fuel Milage
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.
Re: Head Porting for Fuel Milage
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.BobbyB wrote: ↑Thu Feb 02, 2023 12:24 pmI 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.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Studebaker-Packard V8 Limited
Obsolete Engineering
Re: Head Porting for Fuel Milage
How can I control the EGR valve to improve mileage if I eliminate the computer?Tom68 wrote: ↑Sat Jan 28, 2023 4:21 pmIf you do build a low rpm high torque engine, EGR could be used to reduce pumping losses.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.
For what it is worth, with every high mileage 2.8 I have torn down has the EGR passages were completely clogged.
Re: Head Porting for Fuel Milage
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.BobbyB wrote: ↑Sat Mar 11, 2023 5:54 amHow can I control the EGR valve to improve mileage if I eliminate the computer?Tom68 wrote: ↑Sat Jan 28, 2023 4:21 pmIf you do build a low rpm high torque engine, EGR could be used to reduce pumping losses.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.
For what it is worth, with every high mileage 2.8 I have torn down has the EGR passages were completely clogged.
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Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Re: Head Porting for Fuel Milage
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.
Re: Head Porting for Fuel Milage
The timing cover has never been off.
Re: Head Porting for Fuel Milage
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?
Re: Head Porting for Fuel Milage
Has anyone ever increased air inlet via cam and head flow and used less fuel?
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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!
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!