Blucuda413
Well-Known Member
If they are pleased what difference does it make? To each his own!!!
80/20 Rule
- Thread starter 273
- Start date
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To me you got to start with a ruff idea then go over the requirement over and over again unlit you nail it down.
1st would what I'm willing to live with drivability idle gearing money spent etc..
2nd would be were I want the powerband to be idle-5000 rpm, 4000-8000 rpm etc..
3rd is how much power I want to make within 25 hp.
2 & 3 will tell you how much cylinder head you need and what displacement is required and strength of the parts or you got to make some compromises on 2 & 3 .
4th cam
5th then the CR I would need for the cam and gas I'm using, the only way I'd switch cam/cr is if cr is fixed.
6th gear & stall
7th carb intake exhaust etc..
8th tune for best performance, which might include change out for other parts cam carb exhaust etc..
I don't get why you see CR as 1st?
I could see like doing coatings and lower under hood temps and other things to allow for the highest, but still don't get why the 1st.
Cause say someone just says 10:1 it might force them go with more cam gear stall then they wanted to, not saying you would but see on here all the time, people build an engine 10:1 or and then ask what cam they should use but the also want highway gears no stall and decent idle etc.. lol
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James Camp
no mopar
Someone else said my thinking if you are satisfied with the 80% ,and it fits you wallet,then be happy, if you can get 80% for hundreds of dollars, versus 100% for thousands of dollars , then that's what you are happy with, it goes the same for your house, and especially for your everyday vehicle, myself i have a 2008 ram 1500 i paid $10000 dollars for, my brother has a 2018 dodge ram he gave $56000 for, i'm more happy with the extra $46000 in my pocket and still can travel to the same place and the same speed he does. I will say your priorties change as you get older
You could have made more power if you would have done xxxxxxx..... But at what cost?
You can gain 100 hp with bolt-on's but it might cost you thousands to gain another 20.
You can gain 100 hp with bolt-on's but it might cost you thousands to gain another 20.
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I'll throw some numbers on the BUILD VS. the TUNING.
The hp and AFR gains I posted earlier in this thread were on a new engine.
I paid $5k for the engine and paid a shop to install it along with some other work. I'll be generous and say the removal and install was $1000. (They didn't actually do the swap, but they did remove the old engine and drop the new one in place - loosely bolted to the mounts and trans. Then I had it flatbedded to my garage where I finished it. )
The cost of the dyno runs that day was around $300. I'd have to dig through a file for the actual, but it was at least $250.
Gains.
> Engine with new cam. Untuned about 17 hp gain peak, and an engine with core plugs that weren't rusting out. We can consider the price difference between just pulling the engine and installing new plugs as the baseline or not. So lets say $5000 for around 20 hp.
> Dyno session consisting of 6 runs with customer (me) making the jet changes. Call it $350 for 10 hp, plus the advantages of cleaner running plugs etc etc.
On the other hand I've made changes that cost me money and cost throttle response, torque, and horsepower. What a bargain! But it happens all the time. The advantage of not testing and tuning is not having to face that reality.
Amen!There is no way of knowing unless a back-to-back comparison is done. HOWEVER, I would rather have 80% of the correct part tuned 100%, than have 100% of the correct part tuned 80%
But the magazines, you tubers and 'experts' everywhere make it all seem easy to 'just' bolt-on [fill in the items] of their favorite sponsor or whatever.
That makes sense.
I think the rule 273 is thinking of is the one relating to cost vs performance.
I first encountered this concept in a review of the F20 fighter jet program. I don't recall the stated 'rule' or ratio of cost to performance but thought it was like 90/10 99/1. But I agree with 273 that its probably more a figure of speach rather than some actual rule. My recollection with the fighter jet was the concept was the last 1% of performance drove the costs (and maintanence requirements) through the roof.
Quick search on the internet finds this from Wayback Machine
and these claims:
Among its Teen Series contemporaries, the F-20 was offered as a low-cost option; cost-wise it was estimated in 1983 that the unit fly-away cost of the F-20 (based on a 150-unit buy) was $10.7 million, compared to the F-16/79 at $11 million and the F-16A at $12.4 million. Unit life-cycle costs for the F-20 estimated as high as 40–50% lower than for the F-16. Another estimate of the F-20 found it less expensive than other designs like the $30 million F-15 Eagle,[33] or $15 million F-16 Fighting Falcon.[34] The F-20 was projected to consume 53% less fuel, to require 52% less maintenance manpower, to have 63% lower operating and maintenance costs and to be four times more reliable than average front-line designs of the era.
from Northrop F-20 Tigershark - Wikipedia
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MOPAROFFICIAL
Oogliboogli
I like 73% , makes for some juicy burgers, med well so no blood soaked sponge for a bun.
I agree with with many points but that was my favorite.
Life long 'bang for your buck' kinda guy, that's me.That's what motivated me to dive into head porting. If you know what the head does, you can nail down a potential and work towards it. From the heads down.
Factory iron head cars run great with stock 'lift' cams..
Most people who want to up the cam to a 252-248 type could just as soon swap to headers , a performer, 500 cfm edelcrock , and a good multi spark and timing curve and be just as happy. Honestly most should just do that before the cam swap if they are really trying to maximize something, try maximizing what ya have, needle noggins. Lol Then toss a mild shift kit into it and see how much faster it is. A lot simpler for most novices than swapping a cam and breaking it in successfully.
MOPAROFFICIAL
Oogliboogli
Right near the tippy top in a 600+ range, could, if your heads were marginal initially.
MOPAROFFICIAL
Oogliboogli
People build from all ends of the spectrum..
It could start with a wacky multi carb manifold you have up ON the shelf everyone keeps asking about...
The car, some will build around the existing drivetrain, others have picked up a stroker kit with 11.5 pistons and they're trying to make it work on pump with the right chamber heads and cam combo...
It's like art to some degree, our own Frankensteins... in some cases.lol
You guys get what I'm saying.
It could start with a wacky multi carb manifold you have up ON the shelf everyone keeps asking about...
The car, some will build around the existing drivetrain, others have picked up a stroker kit with 11.5 pistons and they're trying to make it work on pump with the right chamber heads and cam combo...
It's like art to some degree, our own Frankensteins... in some cases.lol
You guys get what I'm saying.
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MOPAROFFICIAL
Oogliboogli
Still driving my '96, headliner sags, needs paint, shocks.. again, but runs great has a brand new killer shifting transmission 'after 265k' and never breaks down, 100% reliable...neighbors, 3 of them recently all bought new rams now.... they see me rolling around for about 10 yrs in this neighborhood rock solid and so they know what a good truck is.
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just means you ain't bought into the keep up with the jonses lifestyle they push on sheeple
First start with what do you really want. Big difference between a drag race car, drive anywhere anytime car, road racer. I always start with great machining. The things that matter the most are: round, straight cylinders; rings that seal at WOT; and great valve job. After that head flow is first, cam and matching components, ignition, intake and carburetor. It is the combination and tune that makes the package. Compression is dependent on the available pistons, cam, and gas to be run. As far as percentages between cost and performance, not sure you can get there. Some people will spend BIG time and money for that last .2 of a second. However you can always spend all kinds of money and go the same or slower. People do it all the time.
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ir3333
Well-Known Member
i think it's more like an 80 80 rule.
80% of the posts are from guys who drive their cars on the street.
80 % of the replies are for max power on the strip....
80% of the posts are from guys who drive their cars on the street.
80 % of the replies are for max power on the strip....
DrCharles
Well-Known Member
I always go by the 90/90 rule:
The first 90% of the project consumes 90% of the budget and time.
The final 10% consumes the other 90% of the budget and time
The first 90% of the project consumes 90% of the budget and time.
The final 10% consumes the other 90% of the budget and time
I'm new to this. I started my first rebuild almost a year ago, and I was very intentionally wanting to spend 20% (or less) effort just to get it back on the road as soon as possible. I foolishly thought it might take a month if I took my time. Then I started thinking about performance, and the whole "well, while the engine is out, I might as well do X and Y and Z." So after consulting the brain trust here, I've learned volumes of how things work in my car and I've slowed my roll. I realize it's not a race to get it done, it's more important to get it done RIGHT. Sometimes I pop the hood and don't even work on it, I just look things over to make sure I'm not forgetting anything.
So after a year of pissing off my HOA with a non-running car in my driveway, I'm thinking I might have the 80/20 deal backwards...80% effort with 20% of the performance potential realized...
So after a year of pissing off my HOA with a non-running car in my driveway, I'm thinking I might have the 80/20 deal backwards...80% effort with 20% of the performance potential realized...
MOPAROFFICIAL
Oogliboogli
Another good one
MOPAROFFICIAL
Oogliboogli
My rule of thumb is this while you can have that 'one' motor ...you should always have two or three motors. One that will run ...and another your building to the height of your horsepower dreams. Always have a back up...
I’d love to do that! Then I’d have the best of both worlds. I could drive my car and work on an engine at the same time. While the rebuild has been fun, I think I done forgot what it’s like to drive the damn car
80 % buy or build the engine with the highest horsepower they can afford, but are surprised from the extensive costs for maintenance and rebuilding after a few miles.......
Building a nice combo for your application makes a lot more fun than missmatched parts and bad fine tuned!
Building a nice combo for your application makes a lot more fun than missmatched parts and bad fine tuned!
Plus I think people throw the hp need with little though like 400 hp out of a LA 360 , even though very obtainable but require more head flow to get. So it steps up the cost a lot for most. A 360 hp LA 360 is easy to get pistons cam 4bbl and headers everything else can be pretty much stock, and probably at that level get away with stock stall and gear, but to step it up 40 hp for 400 hp, your gonna need gear stall after market intake do something to the heads, then by time you figure the cost of that you might as well get aftermarket, then you see trick flow heads are a good deal compared to others, but are a waste on a 400 hp engine so you step it up, now your building a 500 plus hp engine so everything needs to be stepped up, and a 500 plus hp 360 is too radical so now your building a $10,000 408 that might take years to do when you would of been happy with a 360 hp 360. Every engine has it's easy obtainable power with basically a 4bbl, cam and headers with maybe some better pistons after that $$$$$ start to climb specially when you factor the rest of the drivetrain in.
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That's my plan my car came with a 380hp crate 5.9l magnum, plan on putting a milder cam and dual plane on it, since the engine has less the 5000 miles on it. It will be my runner, and I got another 5.9l that will be the engine I'll play with to get the most out of it, and may even do a 408 short block with another block I got far down the road to play around with that.
ir3333
Well-Known Member
without a doubt...a high horsepower number usually comes at the cost of lo rpm performance.
Many well built engines are good performers on the strip but poor on the street unless you use
3.9's or 4.10's and a high stall converter and then not pleasant to drive on the street.
Many well built engines are good performers on the strip but poor on the street unless you use
3.9's or 4.10's and a high stall converter and then not pleasant to drive on the street.
True but it's that middle ground how much cam, how high gear, how low stall, displacement size for hp etc.. before your car isn't streetable and what does person X consider streetable in the 1st place that cause these 10 page discussion
My 380 hp crate engine with a 2800 stall and 2.96 gears is somewhat unstreetable, It's how the car came when I bought it, definitely deeper gears and or a smaller cam would help with the under 2000 rpm or even a dual plane. But for the most part I find it pretty acceptable, Have to drive in 2nd in town or it lugs. And only get a true sense of it's power when I do 40 mph in 1st then drop the hammer, But it still can smoke the tires and pulls pretty good from a stop light. To some it's not a streetable package and some it would be acceptable.
DrCharles
Well-Known Member
Exactly. I put my 451 together with mildly massaged 516 heads (larger exhaust valves, hardened seats, bowl blend) because I had them and wanted to get the car on the road. Despite the poor match to the 272@.050 cam. Low end isn't much (not surprisingly) with a 2.66 four-speed and 3.91 gears. So far I'm just breaking it in, putting around, and tuning, so the presumed fall-off at the high end when it really starts breathing was an acceptable temporary trade to get it on the road.
Meanwhile, I also had Dwayne Porter do a Stage 1 job on some Speedmaster aluminum heads, which are now on the shelf waiting to go on once the heat/humidity breaks and allows working in the garage! 295 cfm @ .650 should wake it up
Meanwhile, I also had Dwayne Porter do a Stage 1 job on some Speedmaster aluminum heads, which are now on the shelf waiting to go on once the heat/humidity breaks and allows working in the garage! 295 cfm @ .650 should wake it up
justinp61
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Not when you start adding stroke.
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