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  #31 (permalink)  
Old 11-11-2008, 04:15 PM
How fast is fast enough?
 
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Quote:
Originally Posted by Cyberats
Thanks again, I know I didn't post my vehicle specs. so it's my fault but it's a 1991 Mercury Grand Marquis LS, heavy four door sedan.
Vortec is 4valve per cyl. heads ? Does Ford make anything similar ?
OK at least I got some idea where my compression should be.

Vortec is not 4 valves per cylinder, I have no idea where you got that idea. And if you are doing this to save money stop right now- it's not gonna happen. Hotroddng costs money, it doesn't save it. We all do this knowing that we will never recooperate our costs.

Sure you can make a living off of it, but then you're not building it for yourself, you're building someone elses car, and they are the ones who once again will never get all of their investment out of it.

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  #32 (permalink)  
Old 11-11-2008, 04:19 PM
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Let's begin again. You said "how is it low octane gives better mpg and less knocking ?" Who said this?

"It's dirty gasoline basically, requiring higher detonation points, not lower comp.." Could you explain what you mean please. I don't know what a "higher detonation point" means to you.

Fuel is formulated to match up with a certain limit of cylinder pressure/heat. At 8.5, you could run just about any gasoline that is available to you at the pump. At 10.0, you'd have to be more selective. A lower octane fuel may not tolerate the cylinder pressure at 10.0. The motor could encounter pre-ignition and/or detonation and destroy itself within seconds.
Of course, there are different limits to the fuel based on ignition timing, combustion chamber shape and size, fuel injection as opposed to carburetion, etc., etc. There are new vehicles on the road with static compression ratios at near 11.0 and they are using pump fuels that would be intolerable to an 11.0 older motor of a design that is inferior to the state of the art designs available today.
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  #33 (permalink)  
Old 11-11-2008, 04:28 PM
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The Vortec

Many years back, was it 1996/1998 ?, GM introduced the "Vortec" engine in Cadillacs and some luxury cars and they DID come with 4 valve per cylinder.

Do you think overall that 4 valves would make for a more economical engine ?

My daily driver is both too old and way into too many replacements to be sold for any reasonable sum of money. I never kept a car for resale value. But you know what ? Owning the car in the next 3 years making it about $15K investment in 10yrs., driving a comfortable, powerful and near luxury car with no glitches = cheaper than replacing a 4-banger every 3 years. Even cheaper than most econo cars you can buy today, baring Kia, Saturn and Hyundai, but I highly doubt any of them will last you 10yrs. with NO investment.
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  #34 (permalink)  
Old 11-11-2008, 04:31 PM
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"Do you think overall that 4 valves would make for a more economical engine ?"

Possibly, but I have no experience with them upon which to base a decision.
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  #35 (permalink)  
Old 11-11-2008, 04:38 PM
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techinspector1

Higher Detonation = more pressure, heat and higher spark to detonate fuel.

Now you are trying to tell me 87 octane detonates before 91 octane ?
I thought a more purified gasoline ignites faster with less heat and pressure.

Every time I use 87, I get knocks in my engine and my Mpgs drop a few points. This was true not only in my EFI but my carb. vehicle I owned before. I owned a carb. GM too, same deal. I maintained the vehicles and did timely tune-ups.

I need details, the why & the who, call me SPOCK, but this is inverted to me, does not make any sense.
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  #36 (permalink)  
Old 11-11-2008, 04:45 PM
How fast is fast enough?
 
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Quote:
Originally Posted by Cyberats
Many years back, was it 1996/1998 ?, GM introduced the "Vortec" engine in Cadillacs and some luxury cars and they DID come with 4 valve per cylinder.

Do you think overall that 4 valves would make for a more economical engine ?

My daily driver is both too old and way into too many replacements to be sold for any reasonable sum of money. I never kept a car for resale value. But you know what ? Owning the car in the next 3 years making it about $15K investment in 10yrs., driving a comfortable, powerful and near luxury car with no glitches = cheaper than replacing a 4-banger every 3 years. Even cheaper than most econo cars you can buy today, baring Kia, Saturn and Hyundai, but I highly doubt any of them will last you 10yrs. with NO investment.
No investment? No car can last 10 years with no investment, not even one that just sits in a garage for 10 years. And today's cars in many ways are manufactured much better than the cars of 10 years ago, and they are lasting longer and longer. When you look at a car's true lifecycle cost you can't beat the econo-boxes. In all reality it would save me money to go out and buy a brand new Cobalt rather than fixing up my Cutlass, yet I still put money into the Cutlass because of personal preferance. But it is impossible to justify it financially.
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  #37 (permalink)  
Old 11-11-2008, 04:57 PM
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Financially

I reached the estimated $15K in 10yrs. with pre-emptive repairs made Before it's broken, including the original $4.6K paid at the dealer (rebuilt the transmission otherwise I would've moved on, no Chevy Caprice to be found in the time I had). So my sum includes repairs made and original price.

What I am trying to say I guess is that any used car you buy, big or small, will save you money over buying a new car, keeping in mind maintainance and preventive repairs will not cost more. In the last 20 years the price for new cars have doubled, while my salary has been halved.

Yes I do need a good job first, open to suggestions.
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  #38 (permalink)  
Old 11-11-2008, 05:01 PM
How fast is fast enough?
 
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I'm an engineer, its not the greatest paying gig, but the job security is really good as long as you know what you're doing. If you're good at what you do in this field it seems everyone knows about it.

As far as your car goes, it sound slike you need a $500 ugly beater special. Try looking at pre-94 s10's, they usally go for less than a G and the 4.3L auto versions seem to last forever, I've seen several over 300K miles on them.
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  #39 (permalink)  
Old 11-11-2008, 05:53 PM
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I guess it's the Greed of Petroleum-Car USA that gets me

Fed up with being ripped off by every stupid millionare in the country.
I love my car only problem is the gas, wouldn't trade it unless a pickup or an suv, why, cause all the millionares buy them for the people in the family who CANNOT or should not drive, thus endangering my life so I need to step up arms . Otherwise yeah, would be nice entering and exiting without breaking my back. Yes, pickups also seem to last a lifetime too, problem is I keep staring after the ones I can't afford nor do I need, like the new F-450.

Are you a mechanical engineer ? I am a computer programmer, ended up doing things incredibly far from my profession, my career never took off, long story, ended up with 16yrs. of consulting and basic techie jobs.

Do you have any interest in designing an ALL hydrogen engine ???
Using only hydrolitic converters no gas storage, pour water in tank.
Would be the biggest kick in the nuts to petroleum-tricar inc. and I would love to have one. My favorite hotrod would be the 1970 Judge, but the Olds would be a close second. I like the designs more, maybe the dual lights, but it's the only detail that matters when you can replace everything inside it.
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  #40 (permalink)  
Old 11-11-2008, 07:13 PM
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Love all this high tech talk guys, but I believe F-Bird'88 hit it on the head. What do you want from an engine? What I wanted in my street rod was to launch and be the first to the end of the next block! What I have is a 4000# 2wd Willys Wagon powered by a 350 sbc bored 40 over with 69-70 64cc 041 heads and dome pistons to keep the compression at around 9:1, Th400 2 stage shift kit w standard stall converter. I like the buck board ride from leaf spring suspension and a 54 GM 1/2tn PU straight axle w 11" discs and power steering. I told my engine builder what I wanted from my motor and he suggested the Elgin P1120 Pro stock cam which is barely above stock. I am running an open gear 10 bolt 373 ratio that will skid my front tires rather than burn a rear due to the weight factor on the *** end! I love the way it launches! So as it is important to have the sound effects of a lumpy engine for some guys, look out for the fellow with the right combination! Kinda makes you want to pull up and try me docent it? I guarantee that while you're giving a noisy smoke show I will be gone!!! However I do shut down at 100mph so I wont break the original speedo. All this on pump gas. For daily driving I run 87 but always have the option for 91 or higher if I want to mix or run at the track. My daily driver tires are 275x60x15 on 10" Cragars. For a little more squirrel I can run 295x50x15's. The best I'll ever get for mileage is about 10mpg HWY but not normally because I am a serious lead foot at every opportunity, especially in and around town. That's why I built this thing is to have fun. Now days they take your ride for street racing that takes all the old school fun out of Hot Roddin and Constructive Cruisin! The main thing is to learn and enjoy what you're doing and you'll never be disappointed! Imports have come along way, but there is nothing like building and driving your very own American Muscle Machine!!!
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  #41 (permalink)  
Old 11-11-2008, 07:33 PM
How fast is fast enough?
 
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No, I'm a civil, everyone swears I should have been a mechanical when they see me around cars, but I'm into bigger things, literally. mostly landfills right now, but it was water delivery in the past, and may be other piping in the future.
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  #42 (permalink)  
Old 11-11-2008, 09:02 PM
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This might explain it

Quote:
Originally Posted by boatanchors
on a chevy small block - 383 what is the limit on compression when i have to stop using pump gas and go with the high dollar juice? i know some people might have different opinions im just looking for a rough number so i know my limit on this build.
After reading this whole thread, I felt this would be a good link to add. This confirms my lifelong experience's, in building, and tuning engines. Higher compression engines, require higher octane fuels, period.

You can try to run a small lift cam, in a higher compression engine, but you will need to run a real rich mixture of high octane fuel, and tune it perfectly. Larger lift cams, will allow you to cut down on the fuel mixture some, but you still need the higher octane fuels.

Here is a link, that answers your question, I hope.

http://www.faqs.org/faqs/autos/gasol...section-1.html

Stephen

PS: I like to tune them lean and mean, but have no detonation at wide open throttle.

Build yours up to a maximum of 10.3 CCR, so you can still run pump fuel.
It can be tuned to perform this way.

Last edited by carsavvycook; 11-11-2008 at 09:15 PM. Reason: spelling
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  #43 (permalink)  
Old 11-12-2008, 07:21 AM
How fast is fast enough?
 
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Quote:
Originally Posted by carsavvycook
After reading this whole thread, I felt this would be a good link to add. This confirms my lifelong experience's, in building, and tuning engines. Higher compression engines, require higher octane fuels, period.

You can try to run a small lift cam, in a higher compression engine, but you will need to run a real rich mixture of high octane fuel, and tune it perfectly. Larger lift cams, will allow you to cut down on the fuel mixture some, but you still need the higher octane fuels.

Here is a link, that answers your question, I hope.

http://www.faqs.org/faqs/autos/gasol...section-1.html

Stephen

PS: I like to tune them lean and mean, but have no detonation at wide open throttle.

Build yours up to a maximum of 10.3 CCR, so you can still run pump fuel.
It can be tuned to perform this way.
Wow, that means most of todays engines coming off the assembly line can't work! I think we better call up the American big three and let them know they have it all wrong. Silly auto engineers are trying to defy the facts stated on that well made webpage.
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  #44 (permalink)  
Old 11-12-2008, 09:16 AM
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Quote:
Originally Posted by ap72
Wow, that means most of todays engines coming off the assembly line can't work! I think we better call up the American big three and let them know they have it all wrong. Silly auto engineers are trying to defy the facts stated on that well made webpage.
Let me remind you, that this thread is about a SBC 383 Stroker (after market) not factory. Along with raising the compression above the 'factory' compression ratio's.

The OP's question is regarding compression........and pump fuel, and how high can you go.

You have 'twisted' some very good information, given by very knowledgeable members, on this thread. You make it sound like YOU wrote the Book on engine performance. I think NOT.

Last edited by carsavvycook; 11-12-2008 at 10:41 AM. Reason: addition
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  #45 (permalink)  
Old 11-12-2008, 01:25 PM
How fast is fast enough?
 
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Quote:
Originally Posted by carsavvycook
Let me remind you, that this thread is about a SBC 383 Stroker (after market) not factory. Along with raising the compression above the 'factory' compression ratio's.

The OP's question is regarding compression........and pump fuel, and how high can you go.

You have 'twisted' some very good information, given by very knowledgeable members, on this thread. You make it sound like YOU wrote the Book on engine performance. I think NOT.

I did no write the book, I could write a book, but books are only good once so I stay away from it. As far as 383 and aftermarket parts. We could talk about running some of the trick heads out there, equally trick valve train, with a rerouted cooling system and top of the line fuel and ignition control to allow for compression that can go past 12:1 on pump gas.

Or you can run 11:1 on well massaged Vortec's with a carb and HEI...

We're talking about what is possible, not what is common.
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