detonation threshold

[mohrhp]

Hi Heath,
I love your Henry J! I'm repowering my 53 Studebaker street/ land speed racer with an ancient blown 496 KB hemi, and want to run it on E-85. Is 9:1 about ideal with aluminum heads, and if this is a good ratio,about how much boost can I run before I reach detonation? The old rule of thumb for my previous pump gas chevy was 8:1 and 8 lbs.of boost. I know this isn't a precise science, but I need to buy pulleys and don't know where to start. Thanks.

[Heath Daniel]

Hello mohrhp and welcome to the board. Detonation threshold hu? That is a valid question and thanks for asking. Some other people may want to chime in on this one. I know static compression is different that dynamic compression like you get with a blower. We have made all the power we need on E85 and still haven't needed to drive the blower even 1:1 but I would not be afraid run it up there if that's what it took. Of course we run a boost timing retard so I think it would be quite a while before we ran into any problems with detonation. As far as static compression is concerned I personally know of a guy running pump grade E85 on a 15.5:1 big block Chevy with no problems. What size blower are you running and is it injected or carbureted?

[mohrhp]

Hi Heath, thanks for your reply.
My blower is an old Mert Littlefield standard helix teflon lined 14-71. Littlefield tells me they can loosen up the clearances for street use. They say it should produce up to 30 lbs. boost at 35% over crank speed on my engine. I don't think I want to push it that far, but I do want to get what I can out of the fuel.
As for your second question, at this time, I have several strips of duct tape covering the blower inlet...no carbs, no nuthin', but I'm leaning toward twin dominators to gain some streetability-as compared to my other option-an Enderle mecanical injector. I'm thinking somewhere between 16-20 lbs. should be my target.Waddya think?

[Heath Daniel]

mohrhp as you know blowers are AWESOME!!! For the rest of you guys that have never run one you might what to give it a second thought before you do because it will change the way you think about hot rodding forever. You aren't going to require a ton of boost to make GREAT power with a 14-71, even on a 496 ci engine especially on E85. For the street I would defiantly go with the carbs. and E85 will help keep it cool. I'll start with the way I understand supercharging. Boost is nothing more than back pressure that your engine is not able to use so talking about horsepower in terms of boost is irrelative. We don't make a lot of boost (355 ci 6-71 blower 6-7 psi) but our car hauls a**. A 6-71 displaces about 400 ci of air per revolution so we are under driven and still move more air than we can use. With a 14-71, WOW, with all things equal you are moving 800+ ci of air per rev. I would say 1:1 should be all you would ever want and that's leaving you plenty of "boost" to spare. Let me tell you a 1:1 roots blower motor set up right, with the right cam and heads is a BEAST!!! Hope you have your chassis in order because you are going to need it.

[mohrhp]

Hi Heath,
Thanks for your reply.You are correct about boost, it's nothing more than induction system backpressure.I screwed together my first blower motor in 1990, and I've been pursuing crank driven boost ever since. We've had to live with the limitations of pump gasoline for so long, people figured that's all we'd ever have. Then along comes e85 and everyone won't shut up about fuel consumption and the environment. All I saw was 106 octane(!)Sign me up!
I suppose it seems my motor ideas look kinda' looney to a person who thinks 400 H.P. is realy hot. Here's the deal. I race in land speed trials at Maxton N.C. and have learned that to go fast you need aero and you need power. I set out to go 200 M.P.H. in the mile in a car I could cruise to Sonic in. Oh, and I'm not rich-the car looks like hell and I got a smokin deal on the Hemi.I have gone 181 with my old blown iron 454 which made about 600 H.P. To get that last measley 19 M.P.H., I need nearly 1000 H.P.So that's why the old top fuel motor.I don't drive it much on the street as it is, so if the streetability is marginal I'm O.K.(just increases the cool factor)Anyway, pulleys are cheap, so I suppose I'll start out conservative(!) and move up as I go.
Thanks for your input.

[Heath Daniel]

mohrhp, DUDE we are in Charlotte, NC! I have a buddy that goes to speed week or whatever y'all call it in Maxton every year and I told him I was in this year. I kept waiting on them to switch the Hot Rod Camaro over to E85 at Bonneville but they never did. What do you think that thing would have run like? Have you tried any of the Rocket Brand E85 that is 112 octane yet? How much is it? We are going to PRI this weekend so I'll find all of that out and let you know.

[mohrhp]

Heath
If you have any interest in land speed racing, Maxton is a must.It's unique and very laid back.I'm still gathering parts and info on my new combo, and the Studebaker is in pieces, so I've yet to buy a gallon of E85.Keith Turk runs the E.C.T.A.(maxton sanctioning body) and is the owner of the Hot Rod Spl. and is a friend. I've worked on that car! Turk isn't to up on the E85 thing yet. Land speed rules are quirky. if you run a fuel other than gasoline or diesel, you are lumped into the "fuel" classes, so e85 cars could potentially have to run against nitro cars, thus limiting it's use in pure race cars. I just hope to set some records with my street car before some big guns show up!