I am getting pretty close to having my 392 Hemi ready for my model A. I have been debating back and forth with myself about what carbs and induction to run. I have gone so far as to aquire most of the setups I may want to run. I have a 3 deuce setup with Holley 2300 Carbs like the old six pack thing, I also have a 6 Duece Manifold and Stromberg carbs, and a 2x4 brl set up. I have more than one of these Hemi's so none of these will go to waste in time I will use them. yesterday I was going thru some books and the idea struck me why not run a Blower? Running a Blower is always been a dream of mine, but also just out of reach. Today I am old enough that I can afford one of the things so why not. That brings me to the questions about what does a mild "Street" blower motor really need to make it work? For years I have heard you must run low compression, forged pistons, o-ring the block etc. etc and etc. While I have been messing around with these old hot Rods for damn close to 50 years, on this subject I am really at a loss as to what is real and what is not. I know there are a ton of guys right here on the HAMB running blowers so I am pretty sure the knowledge level is there. So what do I need to do to make this happen? The motor now is a 58 392, it is bored .040 with all new inners bearings, .010 -.010 crank. Hot Heads aluminum heads a mild isky cam, EGGE "cast" 9 to 1 compression pistons. I am told by Bob Walker at Hot Heads that in his experience these pistons and his aluminum heads are much closer to 10-1. The motor is close to being ready, I realize I may and probably will need to change the pistons, and before I ****on it up thought I would check with you guys about what I really need. Any help will be greatly found by me.
It some what depends on what you plan on using it for. Just putting around town is one thing. Driving the car with the idea of making some booste is another.
....and if you like some boost, maybe you'll want more....that's when the trouble starts Sounds like a piston change is probably all you really need, if you set the blower up to make less than 10 psi boost. Aim for 8:1 or so compression, run pump gas, have fun.
If your compression is really 9:1 you MIGHT be able to live because of the aluminum heads. You would have to keep a real close eye on your timing and fuel, but cast pistons at that level is a deal breaker. I recommend you buy some nice forged 8.5:1 pistons, run about 8 pounds of boost then go out there and whup up on some Chevvies. -Abone.
Opt for some 8 to 1 forged pistons, get a blower and have some fun! It won't take long to figure it out.
^^^what they said. from an engine that had 9:1 and too much boast. ...of course too many rpm didn't help either.
I think BDS is the place. http://www.blowerdriveservice.com/s...ms-chrysler-polished-blower-kits-c-37_43.html
When I built mine, a 350 Chevy with a 6-71, it was strictly with road use in mind and I set the bottom end clearances tighter than you would for a race engine. I'd recommend forged pistons and you should open up the end gap on the rings too. I'm not at home right now but IIRC I set my top rings at .024 and the second ring at .014 on a 4" bore. First and second rings are moly filled. The compression ratio is 8.5-1 and I run a pretty moderate hydraulic cam, 222* duration @ .050 and a lobe separation angle of 114*. Timing is set with 10* initial and a total advance of 34*, my carbs are two 1850 Holleys with direct linkage, and I run the blower 15% under crank speed and when loafing along at 70 mph (about 2400rpm) it is pulling 16 inches of vacuum, no boost. Give it some throttle and open the carbs and the boost comes up quickly. Geared for the road with a 3.36 rear and 31" tires it gives 17.5 mpg on the highway.
Well done, I did a similar build on a 383 inch using a 1972 Camaro 350 engine as the base. The engine is pulling a 1961 Cadillac around and has been running well for over a decade. It's a lot of fun to drive! Your car must be a lot of fun to throttle up on the highway. I can only imagine how hard it pulls! [emoji41] I want to build a blown early hemi too. It's Iconic! I hope that this thread continues with pictures! Sent from my XT1585 using The H.A.M.B. mobile app
The 392 hemi is a heavy powerful motor and the Model A is a light car. You should have plenty of power as it is. Try it out with carburetors. If you have it tuned right you should have over 400HP if that is not enough think about a supercharger. A supercharger will work with a stock motor if you keep the boost down to 5 pounds or less. But, more power is as easy as increasing the boost which is where the trouble starts. If you don't want to ****ter your motor you need to lower compression, and strengthen internal parts like pistons and rods. The more power the more stress not only on the motor but trans, driveshaft, rear axle, and even frame and suspension. Seriously, in stock condition the 392 would propel a 2 1/2 ton 5 p***enger Chrysler 300 to speeds of 145MPH back in 1958. I don't know how fast a modernized one will propel a Model A but if it is too slow for you, you must be a full blown nut.
I guess you'd probably say something similar about my Chevy II....a stock high perf 427 should be enough, right? but that boost sure makes it more fun (left lane)
Jim, for sure my car is not anywhere near being a nine second machine. I have always admired what you do driving on the road and running the 1/4 mile and doing it with relative ease. My coupe is about 2650 pounds with me in it and with what I think is an honest 400-425 HP at the flywheel it does exactly what I set out to do. Tractable on the street, plenty of torque to set you back in the seat and good mileage out on the open road. My advice to anybody, with any kind of build, just what do you want your car to do? Think about the combination and science it out as best you can. Oh, one more thing- don't put anything on your car you can't fix. Knowledge is power.
Call Tony Ross at Ross Racing Engines, he'll tell you straight up. He is on the Hamb as 'goatroper', I believe he makes the 6-71 hemi intake, the V belt pulleys and drives etc that you'll need for a vintage look. He builds the great blown engines found in Hilton's Hot Rods and they are all built to be driven.
Guys I want to thank all that have responded. I also would like to ad a couple of comments of my own here as a means of talking about why we do the things we do. My little Model A sedan weighs in at 2,415 lbs with me on board and I am not a light weight by any stretch of the imagination. When I built this car last winter I did not have a Hemi for it even though it was built with that engine in mind. I did have some SBC ( and I mean some SBC) that had been laying around the shop as I get it in a trade for some Tractor implements I had. I do not know what SBC it is, don't care and never bothered to even try and find out as it was always just a temporary engine until I found and built a Hemi for this car. I simply wanted to drive the car this past spring and summer, the Small Block runs just great and the car is pretty quick with it in it. As a matter of fact most folks would be completely happy with the car as it is. The Hemi has always been a dream of mine, I want one and I am going to do this. The question though has arisen many times between friends and family of WHY? Why go to all of this trouble? Why tear apart a perfectly good Hot Rod and replace a perfectly good engine? Why spend all of this money and get what in return? My response has remained constant from the beginning " If I have to explain it to you, you would never understand" The same response applies here as well. I mean I certainly do not have to or even need a Blower for this car. It will run and be way faster without a Supercharger than I will ever need. So why do we do these things? I do not know the correct answer to that question, or even if there is a "correct" answer to it. I guess I could be some form of just showing off, but in reality I personally don't give a flying fart what anyone else thinks. I believe it may come from that nostology thing from when we were kids and saw in the magazines all of those old school Hot Rods with there Blowers or 6 deuces, or any multi carb setup. Maybe the reason, it is just cool. I am going to go with that last one, hell that's reason enough "Because it is cool" Hell yea that even looks good written down.
This isn't mine This isn't a 392 it's a 331 This also isn't a Ford But what's wrong with being a full blown nut job?
How much time do you guys spend with the gas pedal on the floor, wishing you had more power? I've known guys who had to have the most powerful blown big block hot rod, who had them wide open for about 10 seconds a year if that. My motto is if you want to go faster, push the gas pedal down farther. If it is all the way down and you wish you had more power it is time to think about more motor but not before that.
I was going to post but I see Jim ( @squirrel ) and Jeff ( @flamedabone )are already here. They are well versed on street blower setups and there will be nothing that I can add. if they say it do it.
Quite a bit, when I'm not driving my blown car. And that one...usually only when I'm going down the dragstrip.
Seldom on the highway, but around town a lot. I can think of more then a few times that some fox body made me wish for another 500 RPM on the big end.
Well guys I ended up pulling the trigger on this Blower deal. I mean what the hell we only live once and it is only money. Blower is ordered and I did also have a set of Ross 8 to 1 pistons being built. I also had to deck the block as it wasn't perfectly square and was a few thousands out of spec, it is now at the machine shop having that done. I must admit that I am a little excited about doing this, something I always wanted to do but just seemed out of reach.
Go for it Hombre! I am going the same route on a Poly 318 because I have always wanted a blower. Being a Mopar fanatic, I can appreciate your love for hemis. Have fun and enjoy the ride. By the way, *****en A! - EM
Did Bob Walker tell you what HP to expect with the setup you had? My wild guess is 600HP. You can double that with 15 pounds boost. Do you think 1200HP will be enough in a 2000 pound car?
The Jalopy Journal
