Re: High compression, High Octane, and Boost??
[Re: 68Bullit]
#152700
11/18/08 02:01 AM
11/18/08 02:01 AM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Quote:
Since lower compression engines are needed to avoid detonation when boost is present, could you then get by with higher compression and boost if you adjust to higher octanes? Whether race fuel or Ethanol (E-85)???? I'm talking compression levels between 10:1 to 11:1 ??? If so, would the boost pressure (lbs.) have to be somewhat lower?
Yes, with the right octane and cam you could run high static compression, but with relatively lower boost than you could with lower static compression. Is your motor already built with high compression and you want to run a blower?
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: High compression, High Octane, and Boost??
[Re: jbc426]
#152703
11/18/08 08:57 AM
11/18/08 08:57 AM
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Joined: Mar 2008
Posts: 571
Western NC
68Bullit
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Quote:
Is your motor already built with high compression and you want to run a blower?
Yes. Already have 10:6:1 compression, and been thinking of converting to E-85. Don't have any forged internals either, but I also know that I will be limited in boost pressure.
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Re: High compression, High Octane, and Boost??
[Re: 68Bullit]
#152705
11/18/08 12:24 PM
11/18/08 12:24 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
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Putting an expensive blower setup on a motor that is not built for it may not be the most cost effective plan.
Are you already getting detonation now?
Have you considered using a programable electronic ignition controller and a small NOS system that also injects race gas from an auxillary tank? Even this could have reliablity/tuning issues.
Remember, speed cost money. How fast do you want to go?
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: High compression, High Octane, and Boost??
[Re: Mr440GSS]
#152707
11/18/08 01:47 PM
11/18/08 01:47 PM
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Joined: Mar 2008
Posts: 571
Western NC
68Bullit
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Quote:
I run just over 10:1 compression with aluminum heads and 8psi of boost on 93 octane. I think the secret is that I use water/methanol injection and the boost level is not crazy.
My engine was built with no intentions of ever supercharging it. It has lived, though, with the exception of the original head gaskets.
Hey 440, that's great to know! I also have aluminum heads and I hear that's a big help. My 10:6:1 360 setup will be somewhat close to yours (in the way of compression). Is your carb modified for the 8 lbs? I wonder what I'd need for a carb to handle boost AND E-85?  Also, how hard was it to install your Water/methanol injection?
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Re: High compression, High Octane, and Boost??
[Re: Mr440GSS]
#152712
11/21/08 09:52 AM
11/21/08 09:52 AM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
I run just over 10:1 compression with aluminum heads and 8psi of boost on 93 octane. I think the secret is that I use water/methanol injection and the boost level is not crazy.
My engine was built with no intentions of ever supercharging it. It has lived, though, with the exception of the original head gaskets.
by that reminds me of my old home-made set-up...I miss that car.
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Re: High compression, High Octane, and Boost??
[Re: Mr.Yuck]
#152713
11/28/08 09:36 PM
11/28/08 09:36 PM
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Joined: Mar 2008
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Western NC
68Bullit
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I bet you do miss that car....for sure. If I'm currently at 400-415 horsepower, and then I add 6 lbs of boost, where would that put my crank horsepower, roughly???? BTW, here's an article I found on a 73 Charger with boost AND E-85. Guy says he would like to try something with the static compression of 10:1 or maybe more! Check it out.... http://www.carcraft.com/featuredvehicles/ccrp_0801_1973_dodge_charger/index.html
Last edited by 68Bullit; 11/28/08 09:38 PM.
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Re: High compression, High Octane, and Boost??
[Re: 68Bullit]
#152714
11/29/08 10:14 AM
11/29/08 10:14 AM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
I bet you do miss that car....for sure. If I'm currently at 400-415 horsepower, and then I add 6 lbs of boost, where would that put my crank horsepower, roughly????
BTW, here's an article I found on a 73 Charger with boost AND E-85. Guy says he would like to try something with the static compression of 10:1 or maybe more! Check it out....
http://www.carcraft.com/featuredvehicles/ccrp_0801_1973_dodge_charger/index.html
I was probably in the same boat the car ran 12.90 on cool days and 12.99-13.05 @ 103.5 on hot days before boost. It was a all steel 3850lb sled. After adding the S/C unit w/o tuning I ran consistantly between 12.08-12.18 @ 114. That was about 5.5-6lbs of boost. Mind you this was a 9:1 cast piston, stock 906 headed Summit 488 cammed 440. I bought an 8psi pulley but never ran it at the track Sold the car in the staging lanes Via cell phone. So I ran it all day thru the pipes, shifting at 5k around 4psi and the car ran 12.40's. I'd guess you'll pick up close to 100 hp and tons of torque.
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Re: High compression, High Octane, and Boost??
[Re: Mr.Yuck]
#152715
11/29/08 10:28 AM
11/29/08 10:28 AM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Car Craft had an article on just this issue, boosting a high compression engine.
They used E85 and made interesting observations and power out of it, surf thier site and see.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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