mythical hemi questions

[mole53]

I got a couple of questions concerning a what-if blown V16 hemi that I am tinkering with.

1) I plan on using two distributors, would the firing order be the same for both distributors or would it

depend on distributor location (see question 2)?

2) Is it thoretically possible to mount one distributor on the right side of the block or should they both

be mounted together on the left side?

3) If I install nitros, are the injectors befor or after the blower?

Thanks in abvance for any info/opinions that you can give, I'll try to post some picks when I get far enough along.

T.T.F.N.

[Ace-Garageguy]

Cool...crazy engineering in scale !!

If you built a V-16 by fabbing up a block and a custom crank to end up with, essentially, two V8 engines mounted end to end, the firing orders on both distributors would most likely be the same (keeping things the same would avoid some imbalance problems), but one half of the crankshaft and the corresponding distributor would be cranked a few degrees to allow the firing pulses on one 'engine' to come between the firing pulses on the other one (so that all firing pulses would still occur every 2 complete crank revolutions).

if you were going to that much trouble, there's no reason you couldn't fab a new front timing cover that had distributors on both sides. A lot of work, but entirely possible (I'm assuming you're planning to start with the 426 Hemi that had the distributor in the front). You could also use a setup like some fuel drag engines and run two distributors or mags on one side.

If you're planning to use the first-gen Hemi as a starting point, which had the distributor in the rear, the best solution would probably be to make up a special, single distributor for all 16 cylinders.

As far as nitrous goes, place the injector nozzles AFTER the blower. Blowers heat the intake air by a huge amount, and the cooling effect of nitrous squirted under the blower acts like an intercooler.

Edited September 22, 2013 by Ace-Garageguy

[ScaleDale]

This is a demo engine set up by a vendor at the NHRA NorthWest Nationals last Summer. The dual distributer setup is used on dual plug engines and provides a double fire for each cylinder, so they match in firing order. As you can see, one is a slave off the other. You would never want these guys to ever get out of sync unless you liked picking up motor parts and writing large checks for oil down penalties. But then you would never get it through tech inspection.

The latest advancement in ignition control is something called a crank trigger. It's a wheel that fits on the crank shaft at the pulley end and has a magnetic or optical sensor on the block. As the wheel rotates, it passes the sensor and sends a firing signal to the distributor. This replaces the need for the cam shaft to detect the firing point. A programmed box that distributed the voltage to the spark plugs could replace the need for a distributor (as we know it) all together. Rocket science meets hot rodding once again. (Nitromethane was one of the early rocket fuels before the drag boys got ahold of it...)

Dale

IDEOT EDIT: Missed that v16 thing. Never mind, I'm not the droid your looking for...

Edited September 20, 2013 by ScaleDale

[Ace-Garageguy]

This is a demo engine set up by a vendor at the NHRA NorthWest Nationals last Summer. The dual distributer setup is used on dual plug engines and provides a double fire for each cylinder, so they match in firing order. As you can see, one is a slave off the other. You would never want these guys to ever get out of sync unless you liked picking up motor parts and writing large checks for oil down penalties. But then you would never get it through tech inspection.

The latest advancement in ignition control is something called a crank trigger. It's a wheel that fits on the crank shaft at the pulley end and has a magnetic or optical sensor on the block. As the wheel rotates, it passes the sensor and sends a firing signal to the distributor. This replaces the need for the cam shaft to detect the firing point. A programmed box that distributed the voltage to the spark plugs could replace the need for a distributor (as we know it) all together.

Dale brings up some good points. The distributor setup he's shown is for dual-plug heads on a V8. It COULD be used to fire 16 plugs in a single-plug V16 engine with simple modifications.

And, if you want to go current technology, a crank or cam-position sensor could simply drive a logic box that in turn would fire individual coil-packs adjacent to the spark plugs, like this...

Edited September 20, 2013 by Ace-Garageguy

[mole53]

Thanks guys, the info and pictures are just what I needed. I was originally going to go with two plugs

per cylinder, but that was giving me a headache just trying to figure that out. Dale, your not the only

defective droid!

Edited September 20, 2013 by mole53

[mole53]

Thanks guys, the info and pictures are just what I needed. I was originally going to go with two plugs

per cylinder, but that was giving me a headache just trying to figure that out.

Thanks guys, the info and pictures are just what I needed. I was originally going to go with two plugs

per cylinder, but that was giving me a headache just trying to figure that out.

May the schwartz be with you........Space Balls

[LDO]

A 32-plug V-16 would be awesome. A company called MMR (Modular Mustang Racing) does a mod for Ford's 4cam V-8 in which they drive a distributor off one of the overhead cams. They drill a precisely placed hole in the front of one of the valve covers and the distributor lays down horizontally in front of the valve cover. I think a DOHC V-16 Hemi with a twin distributor setup on each side of the engine would be wild.

[blunc]

I think if you're going to use a single distributor (which I personally prefer but would have problems with plug wire length and some associated timing issues) that the cap would be enormous if also used with large plug gap and high energy ignition coils. There's a reason the GM HEI caps are almost twice the size of regular point/breaker type ignition hardware.

Individual (or dual) coil packs would be best for a new engine development with port injection. If you go this route, remember to mount a throttle position sensor and oxygen sensor otherwise your engine management computer will never go open loop (or is that closed loop, it's been so long...)

[Ace-Garageguy]

The problem of plug wire length mentioned by blunc could be solved by mounting the distributor in the center of the block, as Jag did on this production V12. Though it was a SOHC engine and distributors could have easily been driven from the cams as LDO suggested (and has been done on a lot of engines from Porsche, Maserati, Ferrari, Abarth, etc.) Jag chose to run a jackshaft where a cam would be in a pushrod engine. Absolutely no reason you couldn't do the same in your 2-Hemi Chrysler V16. This photo shows the distributor drive boss in the Jag block casting.

The 16 wire cap shown in post #2 is an actual Porsche unit for the flat 16 shown below, and solved the terminals-too-close-internally (possible flashover problem) by using a double-decker rotor, with staggared terminals.

PHOTOS: open internet sources, used under "fair use" definition

Edited September 21, 2013 by Ace-Garageguy

[Ken McGuire]

Why not have a look at the 16-cylinder engines of the past. Cadillac had a V-16 in the 1930s; Marmon had a double eight and there were more engines of that type in the 1920s - 1930s.

[Fabrux]

For inspiration look into the GMC V12, which was almost two V6 engines sharing one block. Lots of common components with the V6 engines and I think dual distributors.

[Art Anderson]

Cool...crazy engineering in scale !!

If you built a V-16 by fabbing up a block and a custom crank to end up with, essentially, two V8s mounted end to end, the firing orders on both distributors would most likely be the same (keeping things the same would avoid some imbalance problems), but one distributor would be cranked a few degrees to allow the firing pulses on one engine to come 'between' the firing pulses on the other one (so that all firing pulses would still occur every 2 complete crank revolutions).

if you were going to that much trouble, there's no reason you couldn't fab a new front timing cover that had distributors on both sides. A lot of work, but entirely possible (I'm assuming you're planning to start with the 426 Hemi that had the distributor in the front). You could also use a setup like some fuel drag engines and run two distributors or mags on one side.

If you're planning to use the first-gen Hemi as a starting point, which had the distributor in the rear, the best solution would probably be to make up a special, single distributor for all 16 cylinders.

As far as nitrous goes, place the injector nozzles AFTER the blower. Blowers heat the intake air by a huge amount, and the cooling effect of nitrous squirted under the blower acts like an intercooler.

As a thought here: A V16 engine is, of course, nothing more than two 8-cylinder engines in a common block/crankcase. However, in actual practice, generally a V16 crankshaft is built as if the engine were a pair of STRAIGHT-8 engines, siamesed side to side, as opposed to a pair of V8 engines end-to-end. If one were to set up one as having, in effect, two identical V8 crankshafts, with the same firing order on each one, the cylinder power strokes (power impulses could well be overwhelming to the point of breaking cranks with incredible regularity.

The whole idea behind V-16's (and their smaller, "kissin' cousin" V12's) was to smooth out the impulses, originally for luxurious smoothness, but also greater power. This is the firing order of the 2003 Cadillac V16 engine. Note how the firing sequence is spread completely down the crankshaft, and alternated side-to-side. This would be very typical of any V16 in order to protect and preserve the crankshaft: 1-12-8-11-7-14-5-16-4-15-3-10-6-9-2-13. Of all the makes of cars having production V16's (excluding any racecars, or of course, V16 diesel engines--General Motors Electromotive Division built thousands of V16 powered diesel locomotives), only two were built in the US, Marmon, and of course Cadilac (1936-1940). Cadillac used a single 16-cylinder distributor, which worked fine, given that their engines were fairly low-rpm units, probably maxing out at about 4000-4500 rpms, where a racing V16 done from Chrysler Hemi components would likely be called upon to run at significantly higher revs. In this case, a pair of 8-cylinder distributors might make more sense.

Art

[Modelmartin]

For inspiration look into the GMC V12, which was almost two V6 engines sharing one block. Lots of common components with the V6 engines and I think dual distributors.

A friend has one of those engines in a firetruck and it is pretty cool. The only unique parts to it are the block, crank, cam, and oilpan. It has two intake manifolds, distributors, air filters, etc.

[Modelmartin]

1) I plan on using two distributors, would the firing order be the same for both distributors or would it

depend on distributor location (see question 2)?

T.T.F.N.

Seriously! Who checks the firing order on a model? I built one model years ago with the firing order correct and nobody noticed!

[Ace-Garageguy]

As a thought here: A V16 engine is, of course, nothing more than two 8-cylinder engines in a common block/crankcase. However, in actual practice, generally a V16 crankshaft is built as if the engine were a pair of STRAIGHT-8 engines, siamesed side to side, as opposed to a pair of V8 engines end-to-end.

If one were to set up one as having, in effect, two identical V8 crankshafts, with the same firing order on each one, the cylinder power strokes (power impulses could well be overwhelming to the point of breaking cranks with incredible regularity.

Art

I edited post #2 that Art is quoting to better explain what I had in mind, and to reference the relationship of the angular separation of the crankpins to obtain an even firing order on what would be, essentially, two V8 engines end-to-end.

The thing is, the guy is trying to build a Hemi-based V-16 that is PLAUSIBLE in reality, but not necessarily BEST PRACTICE (from an engineering standpoint). At least, that was my interpretation of his question.

I'm assuming a cast or fabricated crankcase (block). Both approaches work in 1:1 from an engineering standpoint.

A custom crankshaft, machined from a forged billet, would be the only cost effective way to go. But follow the logic here...ONE WAY to do it envisions that the 'rear' section of the crankshaft COULD be cranked the requisite number of degrees so that the firing impulses would come between the firing impulses of the 'front' section of the crankshaft, so even though the two 'separate' V8 engines would have the 'same' firing order, NO firing impulses would occur simultaneously. Both ends of the engine would be inherently balanced as V8s. Not an ideal solution, but not necessarily a crankshaft-destroyer either. The advantages would be that production heads could be used, and extensive re-engineering is avoided because angular crankpin spacings remain the same as on the original Hemi, and keeping the firing-orders stock avoids the necessity of designing entirely new camshafts with revised adjacent-cylinder lobe separations (necessary with a revised firing-order). It would be a lashup-engine for a showcar, which is what I (possibly mistakenly) assumed he was after.

The BEST way to do it would of course be to design an entirely NEW crankshaft with a correct V16 firing order, which would also allow a shorter block to support it. The problem then becomes that production heads couldn't be used because bore spacings would probably change. You could of course 'base' the combustion chamber design on the old Hemi, and cast entirely new heads with 8 chambers to work on the new block, but the old Hemi chambers and porting, while trick for the '50s and '60s, are pretty old fashioned these days. So why not design OHC, 4-valve heads that take advantage of today's knowledge of thermodynamics and gas (fluid) flow ? So now we have an entirely NEW, but correctly designed engine, and not at all what the OP had in mind when he started this thread.

Of course, a block casting or fabrication COULD be based on the original Hemi design with the original bore-spacings (but with the bellhousing-end details removed from one and the timing-cover details removed from the other, during design, to allow for a shorter overall block and crankshaft. Then, you COULD possibly design a crankshaft with original bore-spacings (of the crankpins LENGTHWISE) but with different ANGULAR crankpin spacings to accommodate a correct V16 firing order. You STILL probably couldn't use stock heads, but you MIGHT be able to machine material from the front face of the rear head, and machine material from the rear face of the front head, and come up with a way to seal them together. Or you could try oven-welding the cast-iron heads end-to-end...but I wouldn't. You'd STILL have to design an entirely new cam to accommodate the V16 firing order, and modify or fabricate valve covers. This approach would probably give the BEST LOOKING MODEL of a HEMI-BASED V16. Possible AND plausible ignition systems have already been discussed.

Edited September 22, 2013 by Ace-Garageguy

[comp1839]

WOW!...........i'm sure glad this is a model and doesn't actually have to run.

[mole53]

Thanks a bunch guys, I now have information overload I think I'm going to go with Lee's idea.

A 32-plug V-16 would be awesome. A company called MMR (Modular Mustang Racing) does a mod for Ford's 4cam V-8 in which they drive a distributor off one of the overhead cams. They drill a precisely placed hole in the front of one of the valve covers and the distributor lays down horizontally in front of the valve cover. I think a DOHC V-16 Hemi with a twin distributor setup on each side of the engine would be wild.

I am using 1 plug per cylinder, I have enough trouble drilling 8 holes in a distributor cap, the thought of 32 sends my fingers into spasms.

check ya'll on the flip side.

[Ace-Garageguy]

Thanks a bunch guys, I now have information overload I think I'm going to go with Lee's idea.

I am using 1 plug per cylinder, I have enough trouble drilling 8 holes in a distributor cap, the thought of 32 sends my fingers into spasms.

check ya'll on the flip side.

So, if you use a Mopar early, 426 or "modern" Hemi, there's nothing on the heads to drive distributors from. The laying-on-the-side distributor drives on the heads ONLY work with an overhead-cam engine, which the three generations of Mopar Hemis aren't..they're pushrod motors.

[ScaleDale]

MSD makes a belt drive distributor that could solve the where to put it issue. It runs off a camshaft pulley and mounts parallel to the ground.

Link at Jegs: http://www.jegs.com/i/MSD-Ignition/121/8712/10002/-1?parentProductId=761249#moreDetails

EDIT: pic: It's in the lower right.

Dale

Edited September 23, 2013 by ScaleDale

[Mike Kucaba]

'ya know everyone makes good points on this concept, and realism is great to try and achieve but this is supposed to be Mythical

[LDO]

If it's based on kit parts, he could use the experimental DOHC hemi heads from AMT's '70 Dodge Coronet. I believe the current release is the "Dirty Donny" issue.

[blunc]

'ya know everyone makes good points on this concept, and realism is great to try and achieve but this is supposed to be Mythical

if it's gonna be mythical then it doesn't need a distributor... or an alternator bracket.

[mole53]

Mike I agree, we all have gotten caught up in the engineering and forgot the mythical

[blunc]

Mike I agree, we all have gotten caught up in the engineering and forgot the mythical

don't get me wrong on this...I like the engineering part of it...

I was thinking that if there were more than one distributor that setting the timing would be a bit of a pain and could damage the engine...but since it's only plastic I let that go.

Edited September 23, 2013 by blunc

[ScaleDale]

Electronics are already replacing distributors so just scratching a box with X number of plug wires would work. It would need an incoming power source, though. A small fusion reactor works for me.

With regards to being hung up on detail, I was going through my next victim the other night, a '66 Fairlane GTA to build for Super Stock and the engine block has a crank and piston heads molded into it. It's an old kit.

Dale