Compression ignition gasoline engines
I notice Mazda is going to have a compression ignition gasoline engine that will still have spark plugs for starting and heavy loads. What would be the advantages of such a engine?
Forum Discussion
Boils down to the ultimate PSI on the piston top...factored by many other attributes...
Like the stroke...which begets the length of the crank lever arm pushing on the crank shaft...and having more PSI on the piston top...has more pounds pushing on that longer lever arm
CI (compression ignition) requires a higher compression to ignite the fuel charge. Diesel requires a higher compression than gasoline. Factored by diesel having more BTU's per unite measure over gasoline...which begets higher PSI on the piston tops
Pre-ignition becomes a lesser issue with gasoline when there is no fuel in the mixture...until the 'direct injection' squirts fuel (gasoline) into the CC...but there is a runaway if the injection is before TDC...why higher oxtane is preferred...but...not necessary. That can be managed by multiple squirts (today's injectors are now fast enough to have several squirts for each Otto Cycle...The main difference between Otto cycle and Diesel cycle is how the heat is supplied to initiate combustion. However, in practice, a compression ratio of 20 can be achieved in a Diesel engine. Therefore, the Diesel cycle efficiency rises up to 64.7%.)
There is even a combo setup in testing...manifold injection of gasoline and diesel/gasoline inside the CC. This cleans the intake valve that direct injection gasoline has a problem with (Ford's ecoboost)
Been waiting/watching GDICI for a few years...wish it to become mature enough and after market folks offering something for my 1996 7.4L big block...
Like the stroke...which begets the length of the crank lever arm pushing on the crank shaft...and having more PSI on the piston top...has more pounds pushing on that longer lever arm
CI (compression ignition) requires a higher compression to ignite the fuel charge. Diesel requires a higher compression than gasoline. Factored by diesel having more BTU's per unite measure over gasoline...which begets higher PSI on the piston tops
Pre-ignition becomes a lesser issue with gasoline when there is no fuel in the mixture...until the 'direct injection' squirts fuel (gasoline) into the CC...but there is a runaway if the injection is before TDC...why higher oxtane is preferred...but...not necessary. That can be managed by multiple squirts (today's injectors are now fast enough to have several squirts for each Otto Cycle...The main difference between Otto cycle and Diesel cycle is how the heat is supplied to initiate combustion. However, in practice, a compression ratio of 20 can be achieved in a Diesel engine. Therefore, the Diesel cycle efficiency rises up to 64.7%.)
There is even a combo setup in testing...manifold injection of gasoline and diesel/gasoline inside the CC. This cleans the intake valve that direct injection gasoline has a problem with (Ford's ecoboost)
Been waiting/watching GDICI for a few years...wish it to become mature enough and after market folks offering something for my 1996 7.4L big block...
Posted By: BenK on 06/01/14 04:29pm
Comment that the 'fashion statement herd' has driven the OEM's to drop
the 'truck' from most all SUV's
I keep my vehicles forever and with the latest on these trucks and even
vans, will keep my GMT400 Suburban even longer
Yes, the small block is very capable, but nothing like a big block. Again
say it is like trying to explain sex to a virgin... :)
To back that up with experience, I LOVE small displacement ICE's that
spin up there...but...not for my trucks. Closest to that would be my
Silverado (see sig) and it's 5.7L that used to beat up stock muscle cars
My 2 seater's 3.1L (hogged out 2.7L & diesel crank, CC'd, cam'd,
flowed, matched, etc...etc) is rated ~350 HP and red lined at 7K
(builder says good for 8K, but I'm not going there with an in-line six
circa 1969)
Waiting for the day I decide to rebuild the 7.4L...noodling forced fed
in some fashion...along with a better cam and breathing...or even
GDICI components...if can find them
A 5 speed manual too...sorry Jeremiah...back to your topic
I checked out the Excursion when it came out. Not enough capacity
compared to my Sub. Again when they refreshed the engine options. Nope,
still not up to my Sub's performance. Didn't like the diesel in either
the Sub or Excursion.
Do prefer the live axle front, but not the way Ford did it. Love my
IFS, but dislike it much off roading.
Get 7-8 towing a +8.5K, 28foot boat from sea level to Lake Tahoe.
City is 10MPG. High way is 12.5MPG and some times (often enough to
claim it) get 15.2MPG fully loaded with my volleyball team going to
tournaments (6'4 guy tallest and gals 4'11 with all seats filled) with
gear on the rack and back
John B sent me a Suburban link that I've only glanced at...but a half
ton Sub going for near $100K is nuts and again driven by the fashion
statement herd. Have talked to many of this crowd and when ask them
if they are willing to scratch their sides from the head lights to the
tail lights...get a weird look and ask me 'why?'....
It is NOT a truck to them, but the latest 'station wagon' or 'mini
van'...so 'car' attributes trumpets truck attributes
Towing HEAVY is lost to the OEM marketing departments...
Also, if you look at GMT400's...careful...the brakes are truly awful
but can be made GOOD to almost GREAT. I've out stopped many cars
and a 5 series BMW among them
