330cc and 430cc STANADYNE HEAD AND ROTOR

[ameristar1]

I promise I won't paint it blue.;p I have been entertaining the theory that the reason the engines scatter themselves and pop head gaskets is because of too much cylinder pressure too low in the rpm band. I've noticed that the 6.2/6.5 GMs after they are modified don't do the same thing, and I believe that it's because of the cam timing. It's risky, but hey, what's the worst that can happen? I know it's not gonna idle, it will lope a bit. Between the big lines and the cam timing, it'll sound like a nascar stocker, but it'll pull from 2000 rpms on to when I decide to shut it down.

I'll keep y'all posted, this should be fun.

 

[dyoung14]

I promise I won't paint it blue.;p I have been entertaining the theory that the reason the engines scatter themselves and pop head gaskets is because of too much cylinder pressure too low in the rpm band. I've noticed that the 6.2/6.5 GMs after they are modified don't do the same thing, and I believe that it's because of the cam timing. It's risky, but hey, what's the worst that can happen? I know it's not gonna idle, it will lope a bit. Between the big lines and the cam timing, it'll sound like a nascar stocker, but it'll pull from 2000 rpms on to when I decide to shut it down.

I'll keep y'all posted, this should be fun.

your going to have to lower the compression some to keep the heads on the thing if you plan on getting over 20 psi and the heads intake and exaust manifolds need to be studed

 

[FordGuy100]

9/16" head studs needs to be seriously considered to keep the headgaskets in place. Anybody got a block/head set laying around they are willing to take to a machine shop to see if it would work?

29psi with stock compression is kinda iffy. And I think the valve clearance is close as is, might wanna drop it down some so you can run a bigger cam with more lift/duration.

 

[ameristar1]

9/16" head studs needs to be seriously considered to keep the headgaskets in place. Anybody got a block/head set laying around they are willing to take to a machine shop to see if it would work?

29psi with stock compression is kinda iffy. And I think the valve clearance is close as is, might wanna drop it down some so you can run a bigger cam with more lift/duration.

The cam will drop the running compression. 21.5 to 1 is static, and depending on what I find out about the flow rates for the cylinder heads, I won't run any more lift than I have to, and let the boost do the work. The boost level is based on the rpm where I want to run it. The harder you spin it, the less boost required, and that is going to be the secret to this engine, it's going to be built with a gasser style powerband. Max torque will not be way in the basement anymore, since I am not going to tow heavy with it.
It'll have plenty of bottom end off boost because of the compression and size of the engine, and the throttle response should be wicked, but since peak torque is further up the powerband, and hence peak cylinder pressure, the chance for breakage should be reduced somewhat. That's the theory anyway.
The other thing is figuring out a timing retard, so as the boost and rpm go up, it'll pull timing out of the motor. I don't know if the advance curve can be manipulated like that on a mechanical pump, but who knows.

 

[funnyman06]

Well it seems you have significant knowledge in this area, haha. I look forward to seeing this project progress. Vroom Vroom!

 

[sle2115]

I'm no diesel mechanic, but I'm not sure I follow you...how do you control compression with the camshaft? When a 21.5 to 1 piston comes top dead center, it has compressed the air (in a diesel) 21.5 times atomospheric...in this case, you are going to make atmospheric 29 PSI! Just where is the compression going to go? Static compression is static compression, you can hold a valve open longer and do a basic decompression, but you can't have them open during a power stroke or you will be lighting a fire either in the intake or exhaust, and keep in mind that you need compression for compression ignition (hence the hard starting on a low compression diesel engine). You only have so many degrees of rotation. Also keep in mind, you are spinning a rotating assembly twice as heavy as a gasser! Try running a Ford truck motor 4800 RPM's for any amount of time and report back the results. I've put many of them back together in the machine shop, well, at least those that didn't have a windowed block.

I'm not sure about everyone else's truck, but my truck makes much more horsepower in the mid range than low, 2000 to 2500 RPM my truck will pull a house, 1000 to 1500, it is much flatter.

Anyway, just some food for thought. Sounds like you have it all figured out, I'm anxiously awaiting the results.

 

[funnyman06]

okay this i can answer but i think he might do a better job

edit:

this might help

http://en.wikipedia.org/wiki/Compression_ratio

 

[Diesel JD]

When I have the money to burn, I'm going to build a motor that can take it. Maybe not quite that much power, but buy custom 6.9 pistons to do 18:5 or 19:1 and have the bigger piston pin boss for the IDI turbo rods. Stud the intake, ARP studs in the heads and a single DT466 turbo. No need to get crazy. It probably still will not run with a lightly modded 12V cummins or a heavily modded 94-97 stroke, but it would run rings around a stock one. That's with an intercooler and a DB4 or DB2 with DB4 sized plungers and pressures. I'd love to see 325HP at the crank and a shade over 200 at the wheels, that would be success. And I bet it would last 500,000 miles just like a stocker since I would not use that sick power all the time, just when needed or at the track.

 

[ameristar1]

okay this i can answer but i think he might do a better job

edit:

this might help

http://en.wikipedia.org/wiki/Compression_ratio

Thanks for the response, the wiki article describes exactly what I want to do.
The engine as designed was not meant to do what I want it to do, and the combination of compression and cam timing makes the engine develop maximum force at the lowest rpm. When using forced induction on a combo like the stock setup it amplifies the the bang at the low rpm. icanfixitall talks about how much pressure his motor has, something like 530psi cranking pressure in the cylinder, and that's at atmosheric. Then the boost gets thrown on top of that, driving the pressure up more. Great for combustion, but the stress inside the motor is incredible and because it happens at a low rpm the stress is prolonged. Raising the point where peak torque occurs and extending the powerband exposes the internals to peak force for a shorter time, and provided the timing curve is not aggressive will allow the engine to live longer.
The cam timing will have a decent amount of duration and overlap, so it will lope quite a bit because of the reversion into the inlet tract, but that is intentional. She will pop. And as far as the bottom end is concerned, these engines are not balanced to the nth degree from the factory, that will be taken care of. Plus I am going to invest in a Fluidamper and see if I can do something with the flexplate/flywheel. I may call Balance Masters and see if they can make something that can be integrated into the flywheel.
I am thinking out of the box with this engine, because I haven't seen it done, and most folks think I am crazy for doing it. But the game has to be moved on, and besides, when a 6.2/6.5 GM can beat you to 400hp or more, it's a matter of pride and principle. I want to see this thing do a streetable 1hp/cu in.

 

[sle2115]

okay this i can answer but i think he might do a better job

edit:

this might help

http://en.wikipedia.org/wiki/Compression_ratio

I understand the concept, but it doesn't address hard starting. A decompression device would be the same as holding the valve open, I get that, but that compression ratio loss, will be equal at 1000RPM or 4000RPM. Therefore, you are mechanically altering the compression ratio, which will in turn cause starting problems, that was my point...you can't have your cake and eat it too so to speak, well, unless you are building a SAAB.

So lets say you open the intake at 20 BDC, it's 20 BDC cranking or running unless you are going to put some sort of variable valve timing in it. Ever heard of Rhoads lifters?

Not trying to be argumentative.

 

[ameristar1]

No, nothing like that. There should be plenty of pressure available to start the engine fine, that's why I am not dropping the compression. If need be, I'll wire in a timer to keep the glowplugs on longer. But it'll start fine.

 

[FordGuy100]

See I dont think they are exposed to that much low end pressures. With our turbo IDI's, we dont make that much boost down low. The other day I mashed the throttle in 4th gear and 1000rpm's. 1200rpm's I had 1psi, 1500rpm's I had around 3.5psi, and by 2000rpm's I had 8psi. Thats with a wastegated turbo, with a non gated turbo those pressures would be even lower.

I need to look at that wiki page though . I do think that we can make the power, obviously we have way more than enough fuel. Its the supporting mods that no-one has any experience with that will take some thinking up. I like your train of thought, but then again, the one thing I love about my IDI is the low down torque these things make.

 

[ameristar1]

See I dont think they are exposed to that much low end pressures. With our turbo IDI's, we dont make that much boost down low. The other day I mashed the throttle in 4th gear and 1000rpm's. 1200rpm's I had 1psi, 1500rpm's I had around 3.5psi, and by 2000rpm's I had 8psi. Thats with a wastegated turbo, with a non gated turbo those pressures would be even lower.

I need to look at that wiki page though . I do think that we can make the power, obviously we have way more than enough fuel. Its the supporting mods that no-one has any experience with that will take some thinking up. I like your train of thought, but then again, the one thing I love about my IDI is the low down torque these things make.

Thanks for the response. It's not the boost pressure, it's the cylinder pressure and when the maximum occurs. That's why the truck squeezes your backside at low throttle settings. I'm just pushing things up so you'll have to rev it up. Turning the plowhorse into a racehorse. It won't be too much of a tradeoff in the powerband because of the size of the engine and the compression, so it is possible to "have your cake and eat it too."

 

[6.5dieselman]

could this be used on the old chevy pumps?

 

[FordGuy100]

Thanks for the response. It's not the boost pressure, it's the cylinder pressure and when the maximum occurs. That's why the truck squeezes your backside at low throttle settings. I'm just pushing things up so you'll have to rev it up. Turning the plowhorse into a racehorse. It won't be too much of a tradeoff in the powerband because of the size of the engine and the compression, so it is possible to "have your cake and eat it too."

I kinda see what your saying though. If you have maximum power/pressure's higher in the RPM's, the engine would be exposed to them for shorter amounts of time, as the rpm's are higher, and it would be I guess the word I'm thinking is smoother for the engine to do so. Wouldnt have as harsh of power surges as lower rpm's when each piston goes through the power-stroke, higher rpm's would even it out better. Would probably be better for the bottom end.

Also, if you want to turn those rpm's, custom push rods and valve springs should be on your list as well, correct? Dont want push rods bending or the valves floating.