Oldiron440
Well-Known Member
All I'm saying is a 150 hp stocker will accelerate quicker with the lower first gear of the OD and the torque multiplication of a 3.25 or my choice 3.55 gear set than a mildly warmed up 318.
Back Pressure - Can anyone explain?
- Thread starter Bruceynz
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AJ/FormS
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Yes sir,no argument there;
and I have enjoyed that stocker (my winter engine, 5 years running)with rear gears from 2.76s to 4.30s sometimes with a 2.66 low, mostly with a 3.09low, and sometimes with an automatic/2800TC, and at least one or two times with the GVod used as a splitter, behind a manual trans.
But all on the same Smogger-teen with; headers, a TQ, a 5200rpm redline, and nothing else. Every winter a new test-combo, and sometimes two or three different ones in the same winter.
One combo was kindof cool; I would run it up to ~15/20 mph,stuff it into hi gear,let her pull the TQ open, then let her moan to 65, which as you can imagine, took a really long time. A long time to enjoy the roar! I forget which automatic combo that was but I kindof think it was the A998/2.74 low/manual shift and 2800TC. But I forget what rear gear it was.Probably 3.23s.
Do you remember the sound that the 74 Chevy pick-ups made at WOT,with that miserable gutless 305-4bbl, that couldn't do more than 80mph? Hyup, my boss at the time bought a few of those. They would get into high gear real quick, and then it was like the same low rpm from 15/20 mph to forever.You could do 80mph with the secondaries wide open,and you could do 80 just on the primaries alone. Don't ever think about passing.
Well, that sound is what I was going for, except thru the TTIs and dual 3s. Pretty much nailed it.
There's lotsa ways to have fun with a 318 but mine all involved gearing. I never touched that engine except to install some valve springs good to at least 5200. I think it averaged about 135psi, which is pretty lame.
In the end my son liked it so much, he made me an offer I couldn't refuse, and we swapped the tired 360 outta his 84 D100 and slid my 318/A998/3.55s in there on a long weekend. For the next several years that boy had a real good time.
After he wore the truck out, he brought her home to roost; traded it to me for a nice Sunfire I was driving at the time. Kids!............
After that got stolen,he bought my recent acquisition,a very nice 2003 GrandAm GT ..... kids.
After that he got married and the romance was over; that boy became a man.
and I have enjoyed that stocker (my winter engine, 5 years running)with rear gears from 2.76s to 4.30s sometimes with a 2.66 low, mostly with a 3.09low, and sometimes with an automatic/2800TC, and at least one or two times with the GVod used as a splitter, behind a manual trans.
But all on the same Smogger-teen with; headers, a TQ, a 5200rpm redline, and nothing else. Every winter a new test-combo, and sometimes two or three different ones in the same winter.
One combo was kindof cool; I would run it up to ~15/20 mph,stuff it into hi gear,let her pull the TQ open, then let her moan to 65, which as you can imagine, took a really long time. A long time to enjoy the roar! I forget which automatic combo that was but I kindof think it was the A998/2.74 low/manual shift and 2800TC. But I forget what rear gear it was.Probably 3.23s.
Do you remember the sound that the 74 Chevy pick-ups made at WOT,with that miserable gutless 305-4bbl, that couldn't do more than 80mph? Hyup, my boss at the time bought a few of those. They would get into high gear real quick, and then it was like the same low rpm from 15/20 mph to forever.You could do 80mph with the secondaries wide open,and you could do 80 just on the primaries alone. Don't ever think about passing.
Well, that sound is what I was going for, except thru the TTIs and dual 3s. Pretty much nailed it.
There's lotsa ways to have fun with a 318 but mine all involved gearing. I never touched that engine except to install some valve springs good to at least 5200. I think it averaged about 135psi, which is pretty lame.
In the end my son liked it so much, he made me an offer I couldn't refuse, and we swapped the tired 360 outta his 84 D100 and slid my 318/A998/3.55s in there on a long weekend. For the next several years that boy had a real good time.
After he wore the truck out, he brought her home to roost; traded it to me for a nice Sunfire I was driving at the time. Kids!............
After that got stolen,he bought my recent acquisition,a very nice 2003 GrandAm GT ..... kids.
After that he got married and the romance was over; that boy became a man.
ch1ll
Active Member
this is a really cool thread. someone please explain "Fifth Cycle". I have this term used in top fuel racing as in Isky five cycle cam.
The aim is to get the low pressure reflected wave to arrive at the exhaust port during the overlap period when both intake and exhaust valves are both off their seats, this is the so called "5th cycle" or "exhaust scavenging"...
It's tuning your exhaust so that you create negative pressure waves (suction) in the combustion chamber as the intake valve opens. That helps draw in more fresh charge air. This tuned effect has a limited RPM range and depending on the pipe diameters and cam overlap involved can create a power detriment to RPMs outside that tuned range. So it has to be scaled and matched with where you want to be making your extra power. For big trucks it's down low, for drag cars it's up high.
It's tuning your exhaust so that you create negative pressure waves (suction) in the combustion chamber as the intake valve opens. That helps draw in more fresh charge air. This tuned effect has a limited RPM range and depending on the pipe diameters and cam overlap involved can create a power detriment to RPMs outside that tuned range. So it has to be scaled and matched with where you want to be making your extra power. For big trucks it's down low, for drag cars it's up high.
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