The elusive 224/3.7 MerCruiser banger

This is the boogieman for my application:
From the research I have done the only problem(s) with these engines is the water pump system will weep because the cam seal will fail, the alternator sucks and if you over heat it with the iron head it will leak the head gasket. So in stock form if you solve the first two issues that leaves the head sealing issue if it overheats. Decking filling or block reinforcement could be a death-nail to my build. I will be running this thing for up to 24 hours strait. When you consider closed course road racing you are essentially running two drag races per lap down the front and rear stretches. We can easily run 450-650 laps per race. That is 1000 hard pulls per race. My boogieman is if I screw with the water jackets and cause hot spots in the cylinders or restrict the general cooling capacity I might be throwing well over a 1000.00 in other block machining tricks in the trash. My build is about freeing up frictional horsepower rather than increasing the RPM it was tested and designed for. Yes, I will be slightly increasing cylinder pressures but I want to do this at the designed piston speeds and with great reluctance on the turbo side of things...

I'm getting closer and closer to just copper o-ringing the head and EPDM o-ringing the block with the stock cylinders.

But at this point and time... I'm in the realm of listening to the most experienced 470 guy on this forum and just running the FACTORY head gasket. Whom made lots of power and reliability with that setup and went 186mph. lol.

 

Has anyone EVER seen any dyno numbers on a 470 build? The only numbers I have ever seen was the dragster that got 470HP@7500 on meth.

 

I havent even heard videos of one running besides mine. We put all the specs in to and engine building program and that is how i got my numbers.

 

Here's some videos...

 

Wow! I just found this post on another forum- from 2003 by none other than Jon Kaase himself.

"We built one of these in 1982. It was 243 inch with a 4.020 stroke(offset ground stock crank to 2.200). We used a nascar boss 429 hemi head and ended up having to use Webber carbs. The vibration and intake pulses were too severe for Holleys. It shook so bad I had to get rid of the Crower steel rods and use BME aluminum. Also had to weld straps to the counterweights. We reground the flat tappet cam and got by with the stock chain and gears.
It made 400 ft/lbs @ 6000 and 400 HP @ 8000. Woody Mays ran it in a dragster for a few years. 8.70's I think. It changed hands a few times and ended up in Il. I saw it a few years ago at Cordova in a roadster. After 20 years I think it still runs.
I orginally built this engine to test cylinder heads cheap. This was when I learned my lesson that nothing is the same with a four banger as a V-8!
Kaase"

 

It's valuable hearing what Kaase says about the Holley. So maybe the draw thru turbo even at low boost will actually help smooth out the intake pulses. Because I really want to run my Holley setups.

 

Holley sells off road conversion kits to handle fuel slosh

 

Yes that is solved with spring loaded seats and raised bowel venting. However, nothing can solve the intake pulse that messes with the metering. A large plenum helps the pulse but you lose low-end tq.

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I was referring to no one on the forum posting personal videos. I can go on youtube all day long. And my engine is just a bigger version of kaases with two holley 500s. Works perfectly fine. Oh also, do you still need a roller cam since kaase used a reground flat tappet? Because i used a flat tappet also and i was told that it wasnt going to work well.

 

There was tcheer posted a vid. Yeah, I have to run a roller. I wont make the level of power and economy I need without it.

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Brian, have you put a load on that engine yet? In a car? Can't wait to see it run.

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Not yet. Just got it bolted in the car though. It barely fits. The whole car has been a 5 year project and the engine has been 3 years so its coming close now.

 

So damn cool!

 

Dennis, great to know... Did you ever get a new block? Yours running again?

 

I rebuilt a Mercruiser "120" and ran it in my car until it was time to change its break in oil but was surprised at how much less power it made. I'm presently working on it but I bought another 170 for the car. The best thing I can say about the smaller engine is that it has no tendency to knock but that engine is small and too heavy for its power. I have a supercharger for it but the larger 170 engine is far better. ( I'v another car ready for my 120.)

Scott, I am quite impressed with your engine, your car and its performance. Revs really, really well
Dennis

 

You seen it?

 

Have you posted about your car? I dont remember seeing a video or anything of it.

 

Just watching and taking note's

 

Any updates from LSI?

 

Been swamped at work for the last two weeks... Just wanted to touch base.

 

Me too.

 

So having off thread discussions: Vibration issues were discussed. I always knew piston speed increased at the bottom of stroke and helped with the intake charge. However, I never related it to balance and vibration specifically increased on 4cyl engines...

I have done some looking on the intrawebz and found this valuable info.

Piston speed
An even-firing inline-four engine is in primary balance because the pistons are moving in pairs, and one pair of pistons is always moving up at the same time as the other pair is moving down. However, piston acceleration and deceleration is greater in the top half of the crankshaft rotation than in the bottom half, because the connecting rods are not infinitely long, resulting in a non-sinusoidal motion. As a result, two pistons are always accelerating faster in one direction, while the other two are accelerating more slowly in the other direction, which leads to a secondary dynamic imbalance that causes an up-and-down vibration at twice crankshaft speed. This imbalance is common among all piston engines, but the effect is particularly strong on inline-four because of the two pistons always moving together.

The reason for the piston's higher speed during the 180° rotation from mid-stroke through top-dead-center, and back to mid-stroke, is that the minor contribution to the piston's up/down movement from the connecting rod's change of angle here has the same direction as the major contribution to the piston's up/down movement from the up/down movement of the crank pin. By contrast, during the 180° rotation from mid-stroke through bottom-dead-center and back to mid-stroke, the minor contribution to the piston's up/down movement from the connecting rod's change of angle has the opposite direction of the major contribution to the piston's up/down movement from the up/down movement of the crank pin.

The strength of this imbalance is determined by 1. Reciprocating mass, 2. Ratio of connecting rod length to stroke, and 3. Acceleration of piston movement. So small displacement engines with light pistons show little effect, and racing engines use long connecting rods. However, the effect grows exponentially with crankshaft rotational speed.


SO:
Finding all my power (tq)under 5500RPM will help keep this under control.

However, I'm gonna do a few tweaks. I'm sticking with the 4.39 overbore (+.030) but doing a slight destroked crank grind. I'm gonna go to 3.65 from 3.75. This is a 218ci combination or 3572cc. This reduced stroke will slightly slow BDC piston speed.

Then I will go to a 6.800 aluminum rod. This will stand the rod up more in the cylinder and reduce the harmonic of the varied piston speeds. Also, I'm not going to run the BBC 2.20 journal dia I was going with and go to a SBC journal of 2.100 (stock 2.50) . This will reduce the journal side weight of the crank by 5.97 .oz at each location. This is not reciprocation weight but it will free up some weight off the counter weight side that can be used for knife edging to reduce windage. There will be additional weight saving in the smaller rod bearing. And the aluminum rod's big end that counts towards rotating weight reduction during balancing.

On the reciprocating side I will run very light pistons with with the help of the .150 higher pin location in the piston, light weight wrist pins and thin rings.

And another trade off; I want to keep a significant piston skirt but have it coated. This will help with piston rocking that puts force on the cast cylinder sleeves.

What years did these engines come with a steel crank?

 

Very interesting stuff. Long ago, I found some similar information and seeing a graph of piston acceleration/deceleration was quite an eye opener for me. What I didn't think about was the effect of two piston/rod assemblies having twice the force acting together on the crank at any given time. I did know about the different rates but hadn't thought about them in relation to pairs of pistons in an inline 4. No wonder that these cranks are so beefy.
Also amazing to me, was how small changes can have such large effects on the internal stresses in an engine.
I'm also a subscriber to the long rod, light reciprocating mass approach.

From what I have read, Randy Dupree is right about the pulsing, but the dynamic imbalance contributes to the harmonics, and shouldn't be ignored. I think this engine would benefit from tuned port injection. Signals to carburetors must be huge.

I don't know when the forged cranks were made. The one I have was a gift from an unknown engine.

 

Can you do me a favor and find a PN on it?

 

I read somewhere, possibly on this forum, that the forged cranks were used in the very early motors. I believe the same person suggested the cast cranks may have helped with vibration control.

 

Here is the number on my crank

4565327

 

You know for a fact it's steel? Not say'n you don't know how to check... Just say'n I'm gonna turn the intrawebz up side down looking for a few. LOL

 

Are there any other markings on it?