Supercharged 320 Straight 8 ?

[92geese]

Looking for any information re blower setups for 320ci straight eights... saw a pic from Bonneville once.

Little help?

Geese

[Guest DaveCorbin]

Dear 92geese:

I've seen here in Texas at a car show a 320 with a turbo on it, but it's been several years ago and I don't remember where. I do remember that the installation was fairly well done. Also, I remember a drag or streamliner car with a 671 GMC blower that was front mounted, direct driven off of the front of the crank. The blower sat down low and had a coupling to the damper pulley. This is sometime in the early 50's. I seem to remember that it made about 450 HP, as the engine was overbored around 1/8th to about 340 cubes, had light rods and was full of racing stuff. Also, there's an antique dirt tracker that comes to Hershey every year. Big log manifold, but no blower.

Regards, Dave Corbin

[Rusty_OToole]

Possibly the best and easiest would be a McCulloch or Paxton supercharger. The McCulloch was made by the same people who made the chain saws. It was introduced in 1954 and was designed to work on cars like your Buick. The same blower in modified form is still being made only now it is called Paxton.

For more info on the McCulloch see this site:http://www.vs57.com/

The McCulloch blower was factory stock equipment on 1954 Kaiser, 1957 Thunderbird and 1957 Studebaker Golden Hawk. I doubt they ever made an installation kit for the straight eight Buick. You would have to do a certain amount of adapting. But if done properly you could even pass it off as a "contemporary accessory".

[92geese]

That's great info guys, I concur that the early Mc Cullogh blowers are the answer and have already been chasing down leads on them...(Anybody?) Apparently they are not that easy to find... I have visions of all sorts of weird plenum arrangements, but really need to get a blower into my mitts first. I'd sure prefer to find a vintage unit.

I missed Portland this year but maybe I'll have some luck at one of the smaller shows.

In the meantime the block is readying for rebuild... assuming that I overbore the block (perhaps around .0625)... what compression should I be aiming for?

Somewhere on the internet there is a fellow who did a pretty neat install on a 320 in a '51 Roadmaster?(can't quite remember) He did a real decent job of a Grand National turbo system.

[Guest Straight eight]

Check out Jyrki's Buick Site. <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />

[NTX5467]

As for compression ratio, anytime you start adding artificial cylinder pressure with either a turbo or supercharger, the basic compression ratio will usually need to be in the 8.0:1 range. When I read that in the 1960s, I thought it was crazy as normal hot rod engines back then usually aimed for 12:1 or more. In more enlightened times, unless you have a diesel (which needs a turbo at the normal diesel 20+:1 compression ratios), the 8.0:1 ratios have been better explained. Even with that low of a compression ratio and about 6psi of boost, you'll probablly need some intercooling or fluid injection (ala Olds Jetfire, which had a turbo 215 V-8 and normal 10.25:1 compression ratio), along with some spark retard at WOT, to keep things out of detonation. Seems like MSD now has a spark retard knock sensor stand-alone system, now? Adapting the system used on the middle 1980s Chevy pickups (Electronic Spark Control) would be an option, too, if you can get the HEI ignition adapted.

As David mentions the front-mounted 6-71 blower on the Bonneville Streamliner, that would be necessary due to the space configuration of that vehicle. Doing that on a stock-bodied street vehicle might not work out too well. I suspect the Paxton unit would work better, if bracketry can be configured. Seems like some of the earlier units (ala Studebaker) used a variable ratio pulley, not to mention a wwiiiiidddeee drive belt?

One reason the Paxton-equipped T-birds worked so well was that the supercharger made up for the flow restrictions in the cylinder head intake ports (although things like "swirl ports" were not fully developed back then, nor the complete understanding of "port velocity", although stratified charge was the main technology being investigated back then). Of course, you'll probably need some sort of better intake manifold system (i.e., better than a stock log-style manifold). Plus improved exhaust manifolding too.

As in the Shelby Mustangs (1966 era) that were Paxton supercharged, being carbureted, they had the carburetors mounted inside of a "pressure box" so the pressure inside the carb float bowl was the same as outside of the carb, as in a naturally-aspirated situation . . . relative pressure, inside and out of the carb, rather than what the pressure actually was. Other factory turbo cars (ala carbureted Buick 3.8L V-6s in the later-mid-1980s) put the carb on the intake side of the compressor/turbo, therefore not needing the pressure box, but making something of a "remote mount carb" in the process. One reason that fuel injection works so nice on "boosted" engines.

What you decide to do with the ignition is something else to consider.

I suspect staying in the 5.5-6.0psi boost range would be advisable, all things considered. Not to mention adapting the wastegate control of one of the more modern turbo applications (ala GM 6.5L Diesel V-8) or the Buick 3800 SC V-6. Just a suggestion.

Just some thoughts,

NTX5467

[carbking]

Some other issues to remember:

Stand alone pressurized carburetors require sealing, plus a variable pressure fuel pump

Pressurized carburetors in an airbox require a variable pressure fuel pump.

Either of the above may (depending on the pressure) require adding baffles to the float(s) to prevent collapse.

A pull-through installation is easier.

Jon.

[Guest Straight eight]

Something like this?

[Guest Straight eight]

Here is another view <img src="http://forums.aaca.org/images/graemlins/laugh.gif" alt="" />

[Guest Straight eight]

Here is some more info from Alley Cat.

Actually, upon further thought, some actual numbers might go a long way in explaining why the 263 has more potiental than a 320.

1. bore/stroke ratio. This is a compairison of the stroke lenth divided into the bore size. It shows first off what the potiental rpm range of a engine possiably might be. A. 320: .80

B. 248: .75

C. 263: .77

These are not good ratios. A good ratio would be something like 1.2-3 and up. SBC have ratios like this. There is no way to get these ratios up by much.

Piston speed. This is a average of the distance and rate the piston is travelling. As the piston is approaching tdc and bdc it is slowing and acclerating respectivly. If plotted on a graph this would be a bell curve.

320: 2 x 4.312 x 2000rpm/12= 1437 fpm 2x4.312x5000rpm/12=3594fpm

SBC 302: 2x3.00x2000rpm/12=1000fpm, 2x3.00x5000rpm/12=2500fpm

248:

263: 2x 4.125 x 2000rpm/12=1375 fpm, 2x4.125x5000rpm/12=3437fpm

The chevy is good speed for the size. A lot of engines now have speeds lots lower. Piston speed has a direct relationship to internal friction. None of the str8's are good, but the 263 is lower. Major destroking and boring can change this problem somewhat. You will notice that at 2000rpm the speed is not really very bad, it gets really out of shape at higher rpm's, fast!

Inertial load. This could be a really involved calculation, so I'm keeping it simple. This number showes just what the crank has to handle. We'll just do the weight of the rod.

320 rod: 2lb 2oz, making it easy, 2lb. 2lb x (2000x2000)rpm=8000lb

2lb x (5000x5000)rpm=50,000. 8cyl x 50,000= 400,000lb.

263 rod: 1lb 10oz. 1lb 10oz x (2000x2000)rpm=6500lb

1lb 10oz x (5000x5000)rpm=40,625lb. 8cyl x 40,625=325,000

I've not included the piston, rings, bearings, etc, but in the case of the 320, total inertial weight is well over 1/2 million lbs!!!! The life of your roadsmasher engine is in your rt foot! The weight of the 263 components is not insignificant, but it is lighter by a ways. By now it should be apparent that these engines have some problems. The real advantage of the 263 is that moderen up to date components can, with some work, bolt in. Seriously reducing weight. Moderen pistons alone are worth 5-6 hp a hole,= nearly 50hp.

Rod ratio. This is a numerical value arrived at by dividing the rod lenth by the stroke. I left this last because rod ratio is a very funny/odd thing, it can make or break a engine. It is tied directly to intake volume, if these values are not in balance the result can be a major unhappyness.

320; 8.25/4.312=1.9, a nice ratio!!

248; 7.625/4.125=1.85, not bad

263; 7.375/4.125=1.79, this looks like it going in the wrong direction, but with a shorter rod and deck, rod lenths can be juggled around to fit the intake dynamics.

The 320 looks like it has a really nice ratio but at 8.25 long its not so great. In all cases, a high ratio tends to make a small intake work better, which we have and a really big intake work nice, which we don't have, and never will. A really long rod has a tendency to stay at TDC and BDC for a rather longer time, hindering flow and a few other things, piston needs to be moving. 263 has a smaller intake but it can be opened up and flow vastly improved, and with a little choise in rod lenth, dwell time is reduced and the rod lenth would give more intake signal which would work much better with a "real" intake manifold. Could the 320 be built up to the same level as my 263? Possiably. Would it be easy? No. At that level would it "get" my 263? Yup. alleycat

Alley cat can be found under Team Buick Web site.

[92geese]

Keep writing, I'm reading... although it's a bit like drinking from a fire hydrant... Alleycat answered a lot of (so far)unasked questions... meanwhile the block is ready for machining.... incidentally, the block is a '52 70 series... nice links from Straight8 there...Still looking for a blower...

Geese

[NTX5467]

Some of your numbers look interesting and have some overall bearing on engine performance, power generation, and characteristics . . . but . . .

Bore to Stroke ratio is kind of a relative thing, but not terribly important. In modern times, "undersquare" engines (i.e., stroke greater than bore) can perform credibly. "Oversquare" engines are the more modern "short stroke" engines of the 1950s ohv V-8 era that made those engines run as good as they did (back then).

What has emerged as being important is the area on the top of each piston (i.e., area in the "bore diameter"). One reason that a V-10 with a smaller bore can make more power than a V-8 of the same size--same with a V-8 making more power than a similar size V-6 and probably the same thing with an inline 4 cylinder and 6 cylinder of the same size. I do concur that a ratio in the range of 1.2-1.3 is optimum, but that's not "the whole ballgame".

Stroke to Rod Length ratio . . . this has several implications. One is side loading of the piston against the cylinder wall, which relates to frictional losses. A longer rod also increased the dwell time at TDC and BDC, with longer dwell time at TDC meaning a little more power extraction from the combustion process AND a smoother running engine.

With respect to intake manifold/cylinder head port issues, the closer the ratio is to 1.9-2.0, the more important it is to match the intake flow characteristics to the engine AND it also relates to the relative quickness the engine will rev up and handle higher rpms (look at the 302 Chevrolet Z-28 engine and, surprise, the Chrysler LB 383 . . . Bore/Stroke of about 1.28, Stroke/Rod Length of about 1.9 . . . and the Chevy Can-AM 430 race motor of circa 1969, built specifically for that race circuit and NOT a clone of the existing Turbo-Jet 396 or 427). Some Oldsmobile V-8s have rod ratios of approx 2.0+!

So, with the Rod Ratio of approx 1.90: the engine will rev quickly, have a "normal" power/torque curve situation, need the intake/head porting matched to the engine size for max power/efficiency, have greater "dwell time" at TDC for greater relative power production.

As the Rod Ratio decreased toward the 1.50 range, the engines become more "torque" related than "horsepower" related. With the lessened dwell time of the piston at TDC, the acceleration of the piston from TDC puts a stronger "yank" in the mixture column in the intake port/intake manifold, making the total intake manifold/cylinder head port issues less important than with the higher rod ratios. Such a lower rod ratio engine would run well with "anything" bolted onto it in the way of cylinder heads (intake port, related) or intake manifolds. Hence, "mismatch" is not nearly the issue it would be with the 1.90 rod ratio engine. An example of a low rod ratio engine would be the Chevy small block 400 V-8, which although it is an oversquare motor, has a shorter connecting rod to compensate for the increased stroke and not need a taller deck height on the block to work.

Further on Rod Ratio . . . After I discovered (back in the early 1970s) what Rod Ratio and Bore/Stroke ratios were (plus the article in "HOT ROD" on the Chevy Can-AM 430 V-8 and why it was different and ran much better than any 427 they'd built at that time), I ran numbers on every engine I could get information on (from the Petersen Engine Annuals from approx 1965) to see how it all fit together. In the 1980s, when these things were revealed about why some engines worked better than others, I found an article in "ChryslerPower" magazine which detailed how Chrysler did their initial research on the 1950s ohv V-8s. They determined that anything more than a 15 degree "swing" of the connecting rod would put too much side load on the cylinder walls, so that was the criteria they reputedly used to determine connecting rod lengths and stroke for their new non-Hemi ohv V-8 engine families. From that basic relationship grew the basic architecture of the engine. Although they didn't know about "rod ratios" back then, that was what they were dealing with.

Piston Speed . . . this formula has been around for many years. When I found that formula, I ran numbers on it and discovered that (at that time in the 1960s, the techonolgy to get engines reliably past 7000rpm was not that prevalent back then, except in specialized applications (i.e., NASCAR). Most engines would not make it anywhere near their calculated max piston speed, especially the oversquare V-8s.

Reciprocating Assembly Weight . . . This will include piston weight, with pin. In prior times, engines were built to last and did that with "weight" and "meat" in the components, including pistons, piston pins, connecting rods, and crankshafts. There was (seemingly) little interest in honing things down to get more power and fuel efficiency (from THAT means) back then. In the case of piston weights, a common Chrysler 440 V-8 piston (with pin) weighs approx 1000 grams. That is a HEAVY piston and pin, so one area to "get the weight out" is to use a lighter-weight piston without sacrificing durability in racing situations, plus a lighter-weight piston pin. When the piston gets lighter, so can the connecting rod and such weight decreases also can mean less counterweight weight on the crankshaft (via "knife-edging" of the counterweights, for example). End result, less reciprocating weight = less fuel to accelerate the reciprocating assembly or maintain its rpm level = quicker "zings" = more ultimate power at the flywheel to propel the vehicle.

One other area which can be highly related to these ratios and such is CAMSHAFT timing events, especially the rod ratio. To get the best results, EVERYTHING has to be matched reasonably well--head port volume AND velocity, valve sizing with respect to cylinder bore, intake manifold type and orientation, and compression ratio.

With respect to camshaft/valve train issues, when CompCams came out with their assymetrical lobe camshafts in the later 1970s, the main deal was to get the valve open as quickly as possible and then delay the closing of the valve, hence putting more "valve open" area under the curve. Making the cam act like a bigger cam than the specs would indicate, for example. I put one in a block and checked the event duration and such. I discovered that they did open the valve quicker than stock, let the closing part of the ramp taper down, BUT the valve was also at max lift for 10 degrees of crankshaft duration, whereas the stock cam "hit" max lift for about 1 degree of crank rotation (really quick!).

Another way to affect cam events is with the diameter of the valve lifter itself. Ford used a "mushroom" lifter on their Y-block V-8s from the factory. In that 1950s time frame, a "mushroom" lifter was pretty exotic. With the larger diameter that the cam lobe "saw", the lift curve was different than if the lifter was more normal (smaller) in diameter. In later times, some small block Chevy racers will cut their lifter bores for Chrysler lifters (larger diameter) when they are limited to cam duration and lift in certain racing classes. This is one of those little "mods" that you might not notice unless you knew what you were looking at.

I don't know how it might work with turbocharing or supercharging, but "ram tuning" (as practiced by Chrysler in the 1960s) might be a way to build more low and mid-range torque into the boosted motor. Decreasing the "tuned length" could also move the torque curve upward in the rpm range, too, as they did on the "short ram" version of the "long ram" manifolds (for racing). Where the intake runner would "tune" relates to both the length of the tube and the tube diameter, measured from the base of the carb (in a naturally aspirated engine). Camshaft event timing is related, also.

Knowing how much weight is slinging around inside the crankcase is one criteria of engine capabilities, but it's NOT the only criteria as such (for a gasoline "ignition fire" engine). Generally, though, more CID means more power regardless of other factors . . . provided one "indiscretion" does not overbear other design criteria. If you apply many of the ratios to the "mountain motors" in drag strip cars, they should not work, but they do and build massive amounts of power in the process--but this would be more of a "special purpose" use than anything else.

IF there are some compelling reasons to use the smaller 263 cid engine, for it to make similar power to an engine that's larger, it'll require more "radical" specs and generally be more "peaky" in its power production. Depending upon which class you will be racing in can determine how much custom parts can be used internally (i.e., rods, pistons), which can lessen the impact of some of the "weighty" issues involved. If the engine will be highly boosted and the smaller engine has thicker cylinder castings, that could be a reason to go with the smaller cid engine which would make sense. BUT those thicker cylinder walls could also affect heat dissipation from the combustion chamber into the cooling system, which could also impact detonation tendencies (and possible related internal engine damage as a result).

LOTS of things to consider!

Just some thoughts and observations . . .

Enjoy!

NTX5467

[Guest Straight eight]

Here is the latest from Alley Cat. He's on the Team Buick Site.

Well, actually, I was'ent planing to be "gone" for as long as it turned out to be. The plan was; since my 248 had developed 2 rather odd problems, now was a good time to really build the baby, take photos, bring back the "alleycat" thread, put the photos there, more or less keeping it all under one roof, giving you guys real proof of what can be done. And, since the nationals are going to be about 20 miles down the road fron me, show up with the coolest str8 ever. Probably won't happen now. I've been living in california for about 3 months, will most likely be here till june. I'm a long way from my machine shop. So, I'm at least that far behind. I've got a bench full of the coolest, roughed out parts, you guys are gonna love it!!

Charley, there is only 2 ways I would use a 320 engine; its what s'post to be in the car, or you got a nice one gathering dust somewhere. The inches look nice, but, if you just gotta have the inches, it is possiable to get it out of the 263. It was desighned to get bigger. So, in your case, I would absolutly be looking to get a 263, 50-52, and since you have a stick in your car, you will have to get a stick engine as the cranks are different. However, I think that a "plug" could be made up for a auto crank to convert to a stick crank, but I've not really explored that yet, I don't think its any big deal. With a rear gear change, kiss that silly 10mpg good-bye!!

Actually, chevy, I am mulling over the idea of making some short part runs, the problem is, there are 3 engines, each different, what do I make first?? I DO like the idea of using these late model superchargers that ford&gm are putting on some of their rigs. Sleeper idea fore sure. Everybody thinks "roots" when it comes to schargers, and the kits make it easy. No kits for us. Gotta do it "old school". At any rate you WILL be addressing some internal issues either sooner or later. No free lunch!! More later. Gotta go to the dentist! alleycat

[92geese]

been a while, built a new shop,then built a new 348 engine,.060 over, mild cam, edelbrock 4 bbl... headers comming, still fiddling with the supercharger idea, then I came across this... trust a guy that's into Packards.

http://www.youtube.com/watch?v=opJilgQDZyo&feature=related

if the link doesn't work check youtube supercharged flathead inline 8

Apparently he's been fooling around with it for awhile, he's only blowing in a few pounds, but it sure sounds neat, & proves it's quite do-able.

GeeSe

[Guest Bob Call]

Geese

If you want to boost performance of your Fireball DynaFlash Eight, why not look at modern turbochargers. Look at Edelbock, Greddy and HKS for starters. Anyone of them can advise you and set you up with a kit.