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Thread: Gas to Alky, Compression Ratio

  1. #1
    Senior Member MASTER BUILDER
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    Gas to Alky, Compression Ratio

    Well I just discovered that I have killed or at least mortally wounded my Enderele injected 351W. Budgetary concerns mean this is a season ender for us, before it even started. Sucks, but some days are like that.

    I will be accomplishing a few things at a time over the next few months and since we will be torn down to the block I think it will make sense to plan the move from gas to alcohol during the rebuild.

    No dough for an aftermarket block so this will remain a stock 351W casting, cast crank, stock rods (already polished on the beams and fitted with floating pins). Rods are currently fitted with KB Hyper dome pistons, static compression is at 11.25:1. Heads are cast iron World Rousch 200 (2.02 / 1.60) with 64cc chambers.

    My main question concerns compression ratio. Am I high enough at 11.2 to facilitate this change or am I going to need new bullets? Will hypers stand up to alky in a non-stroked engine? Majority of pistons in $500 or less range are flat tops, dished, or hypers. Any thoughts of what type of performance could be expected if I did stay with my current bottom end and head setup?

    I know I am leaving out quite a bit of detail on the rest of the setup but since I just tore the engine down today and the bottom of the engine is on my mind and will be the first item addresed I thoght I would just start here.

    My Enderle is a Bug Catcher with an 80A-0 pump (belt driven) so I think I should be Ok with pills, nozzles and a metering valve change, maybe a new pre-pump (cell to resevoir) but if I absolutely have to buy new rotating then I'll have to rethink the whole magilla.

    I know trying to make power on a budget is dam near impossible but I have to play the hand I'm dealt. I'm only trying to get a 2800 pund door car into the tens.

    Thanks for any advice.

    Murff

    Just Livin' the Dream, Baby.


  2. #2
    Senior Member EXPERT BUILDER
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    compression

    Hey Murff, I am not an engine builder, I am just a racer. I have ran alcohol for all of the fifteen years i have been racing. I ran SBC untill the last 2 years,now run a BBC. I have never ran one with less than 12.5/1. Over the years i have found that alcohol seems to like 14/1 or better. I have ran 16/1 in a big small block and 15/1 in the current big block with never a problem. In my opinion alcohol likes to hit hard and makes a lot of torque and you need the compression to do that. I dont know anything about a ford engine but i would not think it matters. This is only an opinion the experts will jump in here and tell you what to do. GOOD LUCK!

  3. #3
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    Thanks Davis, that type of compression is what I'm thinking needs to happen, at least 13:1. Now I just need to figure out if there's an OTS piston to meet that or if I have to knock over a couple dozen Stop -n- Robs to pay for customs built pieces.

    Just my luck to be born a Ford guy.

    Murff

  4. #4
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    I know a guy who runs a 10-1 434sbc with Alky and no issue's...

  5. #5
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    Hmmm, interesting. Any other details on the giblets of that engine? And is it carbed or injected?

    Which leads me to ask are ther different requirements for alky carb vs alky injection, in a non-blown install?

    Murff

  6. #6
    Senior Member EXPERT BUILDER
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    No Compression = No Power on alcohol

  7. #7
    I was going to put an alcohol injection set up on a bbc I had and tlaked to the tech guys at Ron's because I was told I needed 14:1 to make it work and they said it works better with higher compression but as long as you can get it to 12:1 or so you should be fine. Also should be able to find some off teh shelf pistons to get you the compression you want depending on your combustion chamber size. My first 351 I built I bought some Keith Black pistons that were 12.7:1 with a 58 cc head and they were cheap too.

  8. #8
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    Chamber size on my heads is 64cc, kind of large without the right piston. I can lose a few cc's by milling. World's tech sheet says 7 thou per cc, max cut of .040.

    With those numbers the best I could get the head to would be 59cc but I don't think I would want to cut all at once.

    I did see that JE Piston offers a 13:1 with a 62cc chamber in their SRP line for $500 & change. Don't know that much about JE or the SRP line but it is a consideration and fits in line with my 'bucks-down' mentality.

    Murff

  9. #9
    Senior Member DYNO OPERATOR
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    Your compression should be ok as it is, but like others have said more should be better. Although I love to brag about my piston company and their quality, I have also used the KB off the shelf hypereutetics and also the newer 2618 forgings that KB has now. If they have a KB 2618 forged in the size, dome profile and compression distance that will work for you, that would be my recommendation.

    You mentioned that the engine has been sort of trashed. Just how bad is this and are you sure? I may build some high horsepower engines but working on tight budgets is my speciality becuase I have had to do it all my life and still now. The majority of my customers are not bucks up and I do what I can with what they have to use and with thier budgets. No crime in being either broke or in putting your priorities in life in proper perspective.

    I may be able to help you with advise and info if you either phone to me or send me a phone number that can be reached at night. Night is better for me, becuase in the day I go nutso with phones and visitors and trying to work. Most work gets down at night.

    Is your crank cast iron or is it a nodular cast? Big difference. You probably have more potential than you think is there.

    Love the under the hood pic. looks cool.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

  10. #10
    Senior Member MASTER BUILDER
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    Thanks Ed, (and Slowman) for the reply and the offers of assistance. I am constantly impressed by the heavy hitters here at RJ that offer to help the local low budget Saturday night guys like me. Pretty cool. And you were correct, damage is not as bad as I initially thought.

    I have a bad trait in me in that I am pretty quick to hang the black crepe paper and drop the flag to 1/2 staff. Being a low buck kind of guy anything that hasn't already been budgeted tends to be viewed as a disaster.

    I had a couple of local builders stop by last night and inspect the internals. General consensus is that I did the right thing by tearing it down when I did. I was able to minimize the damage.

    Block needs to be tanked, all new bearings installed. Rods look Ok as does the crank (cast iron) but rods and crank will get inspected and crank will get polished. Cam and lifters also are survivors. Cylinders, pistons and rings are also still good.

    Damage was caused by a rookie mistake by the engine designer/builder (me!). Roller rockers were installed upside down with relation to the rocker pivots. Posi locks were galling as they were not clamping to the machined area of the pivot. Valve lash had actually clearanced itself an additional .013 as a result. I was trying to adjust ignition timing and fuel curve with .036 lash adjustment.

    All in all it could have been worse. Instead of a $3000 - $4000 rebuild / upgrade I think I can get out for a $300 - $500 freshen up. I still want to get a baseline on this setup and prove the concept of the mechanically injected little block Ford on gas and it looks like I am going to get that chance. If it holds together through the summer then I'll have the time to properly plan out and budget for the alcohol upgrade.

    Thanks again for the offer of assistance. Can I save that offer as a "Get out of Jail Free" card? :lol:

    Murff


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