Bored and Stroked and Mikey, Guys this is the exact information I was hoping would be shared here. While I have been a Hot Rodder and built quite a few cars over the years like 50 years at least, I have no practical knowledge of this blower thing. This is all Greek to me and a little intimating considering all the money that a guys has into a system like this. So you will never hear me say " Oh I know that" or " I knew it was supposed to be like that" I DON'T KNOW. My plans were to run the engine on a dedicated engine test stand that I have, but after reading "D's" remarks I am rethinking that deal al together. The part that bothers me is when you said "don't continue to run it without putting load on it" That makes a hell of a lot of sense to me. So I am going to wait until I have the engine installed into the car before I fire it off. As to the two v pulleys, I am going to have to leave that alone as I need that extra 5/8" to get the pulleys in alignment, I'm not happy with that but it is going to have to be what it is at least for now. Mikey, The one thing I am most concerned with right now is the "Tune" Of all of the engines I have built I didn't really have to concern myself a lot with that. I mean I installed a dizzy, timed the damn thing and off I went. I don't really know how to set a distributer up even, guess I am going to have to learn though. I am under the impression that a blown motor likes Advance--read that "Impression" as I don't have any experience with this. So from what I read something like 8 to 12 degrees initial and maybe like 36 degrees or so at higher rpm, and please correct me if that is wrong. Well how in the hell do you do that? I think it is done with the weights or counter weights in the Dizzy. But how do you determine what you need and don't need with no base line or place to start? Guys thanks for helping me with all of this stuff, without your input I am pretty sure this would be a disaster. As a side note I see that while I was typing this post, that MCMOPAR added a comment. For you folks who don't know that handle Tony is the guy that donated read that "DONATED" a 331 Hemi engine to that young man who is building his first car--with the help of a lot of Hamber's too by the way. Good to hear from you Tony, glad you got some stuff to start building your Hemi. Yes you are right there has been a free flow of information here on this thread. There is a vast wealth of information here on the HAMB and it has been my experience that most of these guys want to share that information when given the chance.
Well.... Good Post. But- When we talk about boost- Isn't that measured at WOT @ 6K rpm according to things? Plz correct me if I'm incorrect...... So- if we're not buzzin 6K, boost levels should be lower...... That's unless you overdrive the blower, and that's with pullies and math. B&S has a good post going on. Too many factors although to get things optimal....... I guess try as you go. Although we would like to be spot on, or damn close the first time...... Hey- I'm no expert, and learning here too.......
Hi Hello Hombre, Hope I can be of some help here for your blower engine project. Some very basic things I have learned working with a close friend that build blowers and billet drives for engines, I will try and get you in the ballpark with these basics. It sounds like you have the main things covered, compression, decent engine components, what you need to look at is finding a good machinist to assist in getting all the pulleys in correct alignment with each other. You need to have only a crank hub to mount the pulleys to, a balancer is not required as the blower does that job, the pulleys have to be as close to the engine as possible to prevent wobble and loading on the crankshaft. Sometime machining of the back of the upper and lower drive pulleys will do this. Once that is accomplished then the tuning is the part that keeps the package driveable and happy. The hemi engine even stock does not require a lot of total timing as the plug is central in the chamber, add the blower and less is better. We would set the engine up with a total of 26 to 28 degrees and have the initial at 10 to 15 and all in by 2800 rpms. The last item is fuel, you need ample supply and it should be set with a gas analyzer for everyday driveability. When under boost you probably can't get too much. One thing you should be running that size engine at 20% over drive, you need at least 10 pounds of boost to have a good time. Last thing the camshaft is critical to having a good happy engine, conservtive duration and lift with wide lobe separtion, let the blower make the horsepower for you. Little long but hope this helps you, this combination made many people happy.
20% OD? WOW! I'm at .03 over to make 5-6lbs @ the magical 6 figure........ Where the heck do you get the 20% #? I wouldn't think Hombre is really John Force lurking here......
I haven't read back into the thread, but what ignition are you planning on running? Also, do you have the specs for the camshaft? Some other things to think about: 1) Start conservative on your initial timing . . . maybe 28 - 30 until you make a few pulls and break it in a bit. Then start to add timing. You'll probably not need more than about 32 - 34 . . . depending on the boost and gas quality. 2) It is super important to not run the thing too lean and detonate it - that will be the death of it in a hurry. 3) If you're new to blowers, blown gas and all that jazz, I highly recommend that you either dyno the motor or dyno the car to get the right tune dialed in. Make sure whomever is running the dyno knows boosted applications (doesn't matter where the boost comes from --> blowers, turbos, etc -- boost is boost). Given all that you've spent, it sure makes sense to be able to really figure out how much fuel and timing the motor needs to run safely - given whatever type of gas you plan on using. 4) Blown Gas has the smallest tuning window (as compared to E85 or Alky) - so it is important to get the air-fuel ratio correct throughout your various load and RPM conditions. 5) You want to dyno the engine with somebody who really knows how to tune the carbs - under boost. It is a lot more than just 'jets' and power-valves . . . to get them right. They may need to change air-bleeds, accel pump cams, squirters, etc - to get a fuel curve that is correct throughout the various load/rpm conditions. If they only know EFI and not your specific carbs - then don't waste your time with them . . . find somebody else. (Or bring them with you to the dyno session). 6) When building/buying headers, I highly recommend that you put in EGT and O2 bungs - so that when you dyno the thing (or tune it going down the road), you can really see what AFR you're running under boost, how hot the EGTs are getting, etc.. I do this on all blown motors (and even NA ones - I like to know what the heck is going on !). You want the EGT bungs as close to the heads as possible, and one O2 bung per header - about 30" back from the heads. Make DAMN sure you don't have exhaust leaks before or closely after the O2 bungs - or the readings will be wrong. Make sure there is at least 12" of exhaust pipe AFTER the O2 bungs, so you don't risk pulling in any outside air. 7) It is HARD to read plugs with today's gas - and you can't afford to be too lean and wrong on the tune . . . so starting out with it pig rich and with low timing on the dyno . . . then make additional pulls and start leaning it out and adding timing. You'll be disappointed with the HP/Torque numbers when it is fat/rich and has low timing - but you'll soon learn that as you lean it out and add timing, that the HP numbers will really come up. 8) Make sure you have a correctly setup fuel system. This is critical! I can't tell you how many high-dollar blown motors have been burnt down on dynos due to incorrectly sized and/or setup fuel systems. I would run a "return type" fuel pressure regulator (not a dead-head type) - and it must be 'boost referenced' to correctly control fuel pressure. Also, a minimum of a #8 line from the tank to the fuel pump (#10 is even better) - and a #8 from the fuel pump to the pressure regulator and a #8 return line to the tank. From the regulator to the carbs you can run #6 lines. Good luck! B&S
BDS is a very good company, I run a Littlefield 6-71 at 15 under. It runs great but its not a hand grenade and it will turn the wheels to snot if you have the desire. The major thing to pay attention to is the fuel system as the previous contributor said. If its not plumbed correctly you will hate the results and it will NEVER run correctly.
EarlyHemi engines do not like more than 36° total lead. It will break cylinder walls because of the crazy pressure loads. The cylinder walls are especially tender when over-bores are large. .
I think the application and build details come into play. It is a very different situation to have a NA engine on gas, versus a higher boosted application, or one running any sort of more exotic fuel. Cylinder pressures are very different given what you're building, the components/specs involved (static CR, cam specs, etc) and the amount of boost being applied and/or the type of fuel you're running (think nitro as the extreme side of this).
...all true, but the OP needs a place to start from and some limits need to be applied or risk the possible consequenses. Back in the old days, you just would never see a blown (early) Hemi with more than 36° at the drags simply due to the carnage left behind so it has always served us well to use that number as a maximum regardless of the rest of the build. Maybe we left so hp on the table but we like to stay conservative in a trade for longevity. We probably use more valve overlap than some others for the same reasons. This is a good discussion and I hope others with blowers in their plans pick up some good info. We can never have too many resources or info. .
A screw type blower is a much better choice for any application ... many benefits and yes they have been around 60 years so they are "traditional"
Age alone does not mean something is 'traditional' . . . one has to consider 'looks' and what was typical back in the day. I think you could post pictures of screw blowers all day on here . . . and guys will be selecting X-71 blowers for HAMB types of builds. Heck, turbos have been on American cars since the early 60s - and when you see the HP levels achieved with turbos and EFI, amazing . . . but you won't see many on the HAMB. (but I'm pondering a setup for Bonneville . . . don't tell anybody!). LOL
I am running 8.25 compression, ross forged pistons. The 392 rods are not strong enough for a blower. Walker will attest to that
bangengears, That is something of a blanket statement. In truth there are quite a few 392's and 354's and 331 running around with blowers and stock rods, so in the case a blanket statement is just not true, if taken purely at face value. I think the statement could be true depending on several things. Like how much boost? How hard is it going to be driven? Is it going to see the track and try and be competitive? Those parameters would dictate a little more what c0mponents need to be in the engine. To just make a statement without knowing a little more about what is going on is just not accurate. Also I personally think when you talking about Blowers and "Old" hot rods a little philosophy needs to sneak into the conversation. That's cool I like Philosophy talk. Why in the hell do we ( any of us) do the things with these old cars that we do? Man that is a big question. I mean if the sole and single goal is to build a car that goes as fast as it can when ever it can then all of us would be better served with maybe one of those crappy looking LS motors. or maybe a really hot Small Block, Or something that does not have to look cool. And there it is folks there is the word's "COOL" and "LOOK" . My little Model A is a bare bones Hot Rod hell with my big ass in the seat it only barely gets over 2,000 'lbs. It doesn't need this engine I am putting in it to get down the road a hell of a lot faster than I would ever drive it. The car does not need a Blown 392 Early Hemi. I do, not that I need it either but I damn sure want it, and I am going to have it. Doesn't make sense really, and I suppose that a lot of folks ( I know a lot of them) who thinks this is just an old mans folly. Well it may be, but I remember very well being a really young guy and setting in that Barber Shop in Mount Pleasant, Texas reading those old car magazines and dreaming about one day. Well that one day has finally arrived for me. This motor, blown or not, will have a very easy life it will see somewhere around 3 to maybe 5,000 miles a year. I don't do the car show thing but every once in a while I do attend a cruise night. Mostly I drive around on these country roads here in Alabama and have a ball. Once a year I drive my Hot Rod back down to Texas for a week or so. That's it, an easy life. I believe the stock rods in this very mild built blown 392, only making around 5 lbs of boost will be just fine, as a matter of fact There is no way in hell that this motor needs after market and stronger rods. If I am wrong about that and I stuff a rod out of the block, then the next one I build will have some of those fancy rods and I will be out some more money, but at this point and time a little more or a lot more money just doesn't make a hell of a lot of difference considering how much I have spent up until this point.
As you just noted . . . black and white answers on engine builds, engine performance, etc . . . are true just some of the time . . . the only answer that is true most of the time is . . . "well, it depends"
Keith or is it Paul, can't remember. You know Hoss I do have all of those extra hemi's laying around in the shop, maybe hummmmm...
HOMBRE. With what you are planing to do, and how you are going to run this engine IMO, you do not need high dollar rods and a ton of high price fancy stuff. I ran the crap out of a 327 sbc in high school that was stock except for pistons and cam. 671 blower with two 660 holley center squirters. That engine saw lots of street racing, beating and high rpm. The blown 406 in my coupe has all the high dollar parts, custom parts, and we race, HARD. My point is you can have a dependable blower motor without all the crazy stuff that will give you years of enjoyment, and be fun. Carry on.
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