Max RPM for da slant?

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805moparkid

805moparkid

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so what is the max rpm for a stock bottom end that has been balanced and has ARP rod and main bolts/studs?
 
thinking f shot peening the rods and the bottom end balance would be to .25 of a gram...

anybody?
 
225 or 170? Piston speed at a given RPM would be significantly different between the two, although I believe the piston weight is similar. That said, I would think 5000 would be a practical limit on a 225 if you expected any sort of reasonable street life. Honestly, port size will probably limit breathing at or before this point. These engines were never designed to be high RPM, high flowing deep breathers.

I'm not sure if there are any dimensional stability/resonance issues with the cranks, but below 5000 these shouldn't be too big of an issue.
 
C130 Chief said:
225 or 170? Piston speed at a given RPM would be significantly different between the two, although I believe the piston weight is similar. That said, I would think 5000 would be a practical limit on a 225 if you expected any sort of reasonable street life. Honestly, port size will probably limit breathing at or before this point. These engines were never designed to be high RPM, high flowing deep breathers.

I'm not sure if there are any dimensional stability/resonance issues with the cranks, but below 5000 these shouldn't be too big of an issue.
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225... and my slant is reving to 6K right now and loving it!...
 
http://www.slantsix.org/forum/viewtopic.php?t=2411&sid=950bc2f45bd1ee8fde81c4ea70aa6627

Doctor Dodge (Doug Dutra)
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Post subject: Re: Max RPM before BOOM! (Mon Jul 16, 2001 11:06 pm) Reply with quote
(User Above) wrote:

: So whats the max you have wound a stock rod
: 225?
: Whats the max anyone has wound a 198 rod 225?


6500 RPM for a 6.7" rod
7000 RPM for the 7" rod combo.
Both were rebalanced.
I think the big advantage to the "long rod" engine is mostly from the lighter pistons and the thinner "low friction" ring set you get with this combo.
A light piston sure helps con rods live longer.
DD
 
Read this about the 170.
http://www.valiant.org/sixup.html



Other slant six performance notes

The 170's relatively short stroke allows it to rev high. Both Russ Shreve and Steve Remington - a Valiant engineer and expert - agree that the 170 is the engine to use if you will turn over 6,000 rpm frequently. According to Russ, a 170 CID slant six HyperPak would deliver a comfortable 182 hp, and turn 8000 RPM if you kept the cam lobes lubricated. He also said that:

It had a shorter stroke than the 225, but the same head and valves. Low end torque was less, but ultimate power was the same. In addition, with the lower block height it was a sturdier engine, and with the shorter stroke could rev higher with less chance of an rpm failure. The Achilles Heel was the cam lobes.

If he [someone upgrading their six] is going for higher power and RPM he is going to need the HyperPak clutch and special clutch bolts. Otherwise he is most likely to have a clutch explosion. I also recommend an explosion shield. A clutch explosion can cut a car in half.
 
Hey Kid,I am just quoting what I have read,I am learning about the /6...
Are you not the /6 Guru?...LOL
TXDart
 
The little sumbitches will twist till a rod comes out the side.
 
805moparkid said:
thinking f shot peening the rods and the bottom end balance would be to .25 of a gram...

anybody?
Click to expand...

Don't bother with the balance job...get the weights close for each cyl.

I didn't balance mine on the advice of my machinest and have no issues.

Balance and smoothness


An inline six engine is in perfect primary and secondary mechanical balance, without the use of a balance shaft. The engine is in primary balance because the front and rear trio of cylinders are mirror images, and the pistons move in pairs. That is, piston #1 balances #6, #2 balances #5, and #3 balances #4, largely eliminating the polar rocking motion that would otherwise result. Secondary imbalance is avoided because an inline six cylinder crankshaft has six crank throws arranged in three planes offset at 120°. The result is that differences in piston speed at any given point in rotation are effectively canceled.
An inline four cylinder or V6 engine without a balance shaft will experience secondary dynamic imbalance, resulting in engine vibration. As a general rule, the forces arising from any dynamic imbalance increase as the square of the engine speed — that is, if the speed doubles, vibration will increase by a factor of four. In contrast, inline six engines have no primary or secondary imbalances, and with carefully designed crankshaft vibration dampers to absorb torsional vibration, will run more smoothly at the same crankshaft speed (rpm). This characteristic has made the inline six popular in some European sports-luxury cars, where smooth high-speed performance and good fuel economy are desirable. As engine reciprocating forces increase with the cube of piston mass, inline six is a preferred configuration for large truck engines.[6]
 
Shaker223 said:
Don't bother with the balance job...get the weights close for each cyl.

I didn't balance mine on the advice of my machinest and have no issues.

Balance and smoothness


An inline six engine is in perfect primary and secondary mechanical balance, without the use of a balance shaft. The engine is in primary balance because the front and rear trio of cylinders are mirror images, and the pistons move in pairs. That is, piston #1 balances #6, #2 balances #5, and #3 balances #4, largely eliminating the polar rocking motion that would otherwise result. Secondary imbalance is avoided because an inline six cylinder crankshaft has six crank throws arranged in three planes offset at 120°. The result is that differences in piston speed at any given point in rotation are effectively canceled.
An inline four cylinder or V6 engine without a balance shaft will experience secondary dynamic imbalance, resulting in engine vibration. As a general rule, the forces arising from any dynamic imbalance increase as the square of the engine speed — that is, if the speed doubles, vibration will increase by a factor of four. In contrast, inline six engines have no primary or secondary imbalances, and with carefully designed crankshaft vibration dampers to absorb torsional vibration, will run more smoothly at the same crankshaft speed (rpm). This characteristic has made the inline six popular in some European sports-luxury cars, where smooth high-speed performance and good fuel economy are desirable. As engine reciprocating forces increase with the cube of piston mass, inline six is a preferred configuration for large truck engines.[6]
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that is really cool shaker!
 
When slant6racer replies you might be surprised, maybe not.
I ran my hyper pak 232 to 7400 a couple of times before I invested in a rev limiter. Damn that second gear! Stock 225 rods with DC rod bolts and TRW forged 60 over pistons. With the rev limiter I was using a 6600 pill. 4 speed car with a 4.88. I heard the same thing about the 170 engines, 8K. I was going to find out with the wagon, but now I am SOL.
 

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My butt hole starts to really tighten at 6400.At 6800 its tighter than a frogs butt.I really feel over 6500 on a 225 is a waste.Guzzi Mark
 
madmax/6 said:
My butt hole starts to really tighten at 6400.At 6800 its tighter than a frogs butt.I really feel over 6500 on a 225 is a waste.Guzzi Mark
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yea no reason for over 6500... i imagine even you car is pettering out by then...
 
7 inch Pauter rods, short Venolia pistons. ( all 6 assemblies weigh the same). The motor makes max HP at 6700 rpm ( it likes to turn up).
 
RPM is not what you think is right. Each combination is different and each motor likes what it likes. You make a pass at an RPM and follow with runs at different RPM's. If it goes faster, it goes faster, if it slows down, it slows down. The question was "max rpm for da slant". I read that as where does the bottom end of a slant give up. That is a big can of worms with a million variables. What were given were real numbers from race runs.
 
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