Thats almost exactly what I did with my test run. Filled the tank up 50/50 with 92 octane pump(Best we have here in Oregon) and e98 Ethanol. That comes out to 106 octane, which aught to be plenty to keep from detonating at least for a couple of test runs. It still triggered knock detection in a few places that aught to be false at this point. I need to tune those out before I can trust what its doing.

 

There is a lot more about using/tuning with a knock detector. When I was running a Grand National it was pretty typical these would trigger false knock. Some people struggled trying to find what was causing it but most found that the downpipe was hitting the floor pan or loose motor mount bolts, etc.. Sometimes it was loose exhaust bolts, etc. Curing false knock can be an issue but I don't know anyone that would ignore real knock.

ks

 

Yeah, I expected I'd start out with false knock as the Megasquirt is all tune it yourself, and the knock setup is from a GM smallblock anyway. I was actually surprised I didn't see MORE knock than I did. It triggered 2 or 3 times across a 5 minute drive but that was it. I expect it won't be too hard to get dialed it from here... Though that might be famous last words

 

Good luck figuring it out properly. It kind of sketches me out dealing with a knock sensor to pull timing due to the false knock/real knock detection, but hey that’s living on the edge for ya haha

 

Looks like the next issue I need to deal with is boost creep.... I'm starting to give it a bit more RPMs on test runs now that everything is working more or less as designed. Got out and romped it and at 4500RPM tapped 19.5PSI.

Now my wastegates opened around 14.7 like they should have(And thats a hell of a noise!) but it just kept boosting. I suspect my internal wastegate ports are a little small for the exhaust flow the big block can put out, and I just pushed right on past the wastegate limit. 20PSI scares the crap out of me that I'm going to break something so I'm going to have to decide to either port out the internal wastegates, or swap to externals. On the bright side, my knock sensors showed no knock at all at that much boost, and with the meth injection I only gained 30 degrees over ambient. I'm gonna pull the plugs to confirm everything still looks good but it seems to be fine at this point. It also has a couple of gallons of E98 in it bringing it to E43(at 102.5 octane) for extra safety as I push it a litter harder.

 

Dang. If you're hitting 20psi that's a lot of power dude. I'm sure you know the math.

Assuming you're at 400hp, NA, at that RPM. Do my numbers work out....like 940hp?

I have no idea what a stock 440 can take power wise but I'm interested to see what happens.

Might be interesting to pull the main caps to see if you've got any signs of walk.

 

Its a hell of a lot of power. My dyno sim puts my build at 524HP NA peak, which if thats TRUE 20PSI puts me at 1239! Even if its only 400 like you said, yeah thats 940HP at peak RPM (Which I never got to...)

Calculating based on injector duty cycle which is a decent way to guesstimate HP I put out 884 at 4500RPM.
All I know is it was time to get new shorts after that pull

Mines a 426 wedge, not the 440 but for this purpose its basically the same thing. I have the advantage of a bit more cylinder meat than a 440 does, which probably works in my favor as well as a forged crank and rods. So its not a stock engine, but its also not built with 20PSI and 1000HP in mind!

I'm definitely going to go through it tomorrow and see how things did. There was no obvious signs of anything going wrong other than too much boost, it pulled beautifully in fact! But it's definitely worth double checking. I'd rather know now if I broke something than later when it lets go.

 

Honestly I wouldn't be at all surprised to see a well tuned combo get to a very high power level.

Maybe the block architecture isn't as stout as a modern LS or Gen 3 hemi, but a BB Mopar is still pretty beefy.

 

Yeah, they can take a lot of abuse. I was talking with my Dad about my build a few days back, and he was telling me he used to spin his 440 six pack '70 GTX out to 7500RPM on the track all season long and it never let go... And that was with the 1000g six pack rods and pistons. The redline is SUPPOSED to be like 5500RPM! And I've heard tons of other stories from Mopar owners over the years with similar abuse.

I guess I'll know in a few days once I pull the pan and check the plugs. I'm not sure I *WANT* to go 20PSI again. I think I'd lose other driveline bits even if the engine held together. But its nice to know it won't just instantly blow up at that much boost!

 

What boost level do you want it to only operate at and also what spring is in your wastegate?

 

The wastegate spring is 14PSI, I've been running it around at that pressure without problem so far and I'm pretty comfortable its fine at that level.

 

Your post said you were seeing 19.5psi

 

Yeah, because I'm seeing some serious boost creep. The wastegate opened at 14PSI, but the boost continued on to 19.5PSI when it should not have.

 

Ok so what I wanted to tell you is the fix for that is put a ~10psi spring and a boost controller and that won’t happen anymore.

 

Hmmm, I hadn't thought of trying that. That might do the trick. Unfortunately the actuators don't have swappable springs so I'd have to swap the actuators. But thats not the end of the world.

The wastegate ports on this housing are apparently fairly small too, people have complained about that online and solved this by porting them out.

 

I see what you mean. When it comes to the additional stuff I mean I guess why not do it while you in there haha

 

Heh, tempting... Its not like if I swap the actuators and it doesn't solve the issue I can't then just go port out the wastegates too.

 

True. I tend to think and speak mainly conceptually. (Internal watergates and all)

 

The internal gates are really designed for something with lower exhaust flow, like a diesel that shifts at 2800rpm, or a 2l 4 cylinder, rather than half of a big wedge motor. Going to an external gate is going to give you a lot more control, just pin the internal gate shut or tack weld it. It's great that the engine held together, and it might last a long time like that.

 

internal wastegate that is restricted by the port size wont get better putting a lower boost spring in.
It will just open sooner in the boost curve but still run away.