how fast can we go roundy round

[85_IDI_4x4]

about those valve springs not working above 14,000rpm.
I was trying to find how to calculate how much force is being exerted on a piston while the engine is running and came across an article from car & driver where the guy was discussing how F1 cars can make 800hp out of 3l and spin 18,000rpm. Turns out Renaults solution to the problem was to eliminate the valve springs all together and instead replace them with mini gas charged piston-and cylinder assemblys.

P.S. Im still trying to find the formulas to determine the forces trying to yank on the pistons, probably learned it in HS physics but have since forgotten. Anyone know how? With a little math one could theroritically find out what rpm the connecting rod bolts would fail or permantly stretch

P.P.S. The article is called "yanking the crank at 18000 rpm" its from a '99 car & driver mag

 

[fordf350dually]

look at like a gsxr 600. they turn insame rpms too. but talkin high rpms my rc car turns 50k rpms and runs like a bat outta hell. it has a glow plug

 

[racer30]

The rotating assembly is heavy, but IMO it has lots of mass that can be cut off to lighten it up. The turbo rods have huge weights on both ends that do nothing for strength. and the rist pin is bigger for surface area, but it is verry heavy. Turbo engines are more prone to rod bearing failure for both more power pounding the bearing and more rod weight swinging on the crank. I was thinking about drilling the center of the rist pins and then cut the weights off the rods beam and balance them. I have seen two engines that have grenaded pistons and none of them broke any rods, just bent them a few degree's at the little end. just some things I have been thinking about doing on my rotating assembly

 

[91idi]

Let me use your engine and I'll let you know the speed and what let go.

 

[85_IDI_4x4]

nah im good. How about you use the bad one in pig? Im waiting to see what lets go in dyoungs engine. Im betting on the rod cap bolts stretching and the piston slamming into the valves

 

[bike-maker]

Anyone know what the infamous Hypermax 900hp motor used for rods? IIRC the force exerted on the bottom end of the motor turned the bottom end of the block into jellow. I think they used a girdle on the main caps to bolster up the bottom end. So their rods weren't necessarily the weak link...

On a side note, if someone actually did do a crazy IDI build; aftermarket rods from a different motor might be used in combination with custom pistons and offset grinding of the crank to not only beef up the bottom end, but also gain some cubic inches in the process.
A good example is a 460 Ford with a .060 overbore, big block chevy rods, and a crank offset ground to produce 512 cubic inches.

As far as drilling out wrist pins; those things are harder than the hinges of hell. No drill bit is going to touch them.

 

[85_IDI_4x4]

well you could probably bore the center out of the wrist pins then.

There is so much crazy info floating around about the hypermax idi. Anywhere from 900 to 1200 hp. And storys of the bottom end turning to jello or it being totally stock and stout as hell. But there is a build on here where someone called hypermax and was told $1500 for a set of rods and $2500 for a bed plate/girdle. Supposedly the same stuff used on the big # idi

 

[blown84]

Uh, about the fuel burning.....my brother calims his old 1.6 VW diesel would spin 7000 RPM........

He also claims that you can make 500 horsepower out of a 5.9 cummins with only a screwdriver.....

The pumps fall FLAT on their faces after about 3000 RPM IIRC, so anything above that would be converting fuel to noise and valve train parts coming out the exhaust.

i dunno bout 500 hp with a screwdriver, but i do know you can put a cummins over 300rwhp and 500ft-lb with a multi-driver screwdriver set and a pair of vice grips.

also, the pumps fall flat on their faces cause thats what their supposed to do. lol. i think its fun puttin my truck in second and rompin on it. "holy **** this things fa-- ...thats it?"

On a side note, if someone actually did do a crazy IDI build; aftermarket rods from a different motor might be used in combination with custom pistons and offset grinding of the crank to not only beef up the bottom end, but also gain some cubic inches in the process.
A good example is a 460 Ford with a .060 overbore, big block chevy rods, and a crank offset ground to produce 512 cubic inches.

i wanna build a 460 outta a 7.3. bored out and sleeved back down to a 4.1" bore and a full custom rotatin assy. that will reach out to 4.36", lower the comp ratio to 19.5:1 and make room for a big cam (no longer an interference motor).

 

[Goofyexponent]

i dunno bout 500 hp with a screwdriver, but i do know you can put a cummins over 300rwhp and 500ft-lb with a multi-driver screwdriver set and a pair of vice grips.

also, the pumps fall flat on their faces cause thats what their supposed to do. lol. i think its fun puttin my truck in second and rompin on it. "holy **** this things fa-- ...thats it?"

No, trust me. I know what all a Cummins is capable of when you start playing with the AFC and fuel plate!!! One of the easiest and cheapest engines to make power from.

I don't know if a pump can be altered to run a shallower fuel curve throughout a longer RPM sweep or not. If you cold get the pumps to fuel upto say 5000 RPM you would de fuel at around 4700...the extra 300 RPM are there, but not really usable.

So lets say you COULD get a cump to do that, and you have a set of stiffer valve springs, that still leaves a LOT of rotating mass in the block. Maybe a set of lighter, stronger pistons and rods and you would have something that would spin a little faster.

The pre-cups are somethign tha would have to be dealt with as well. The combustion starts in that little tiny area and has to flow out into the cylinder. GREAT for a non turbo setup, but not so great for a turboed high revving engine. I have seen pictures of the pre-cups blown out of the engine, I assume it was from using ether to start....TOO MUCH ETHER.

Could the same thing happen at 4500 RPM sustained for a while? We just don't know. Can they be modified to prevent them from coming loose and to help flow a little better? We know we can open them up a little.

Remember, ANY material you remove will lower the compresion ratio a little.

We had a post about head gaskets a while back in another thread, and IIRC Towcat posted about copper head gaskets. The link he provided said that they can make a copper head gasket to fit ANY application, and at about any thickness. Get a thicker than stock copper head gasket and you can REALLY lower the compression ratio and gain some clearance on the valves.

 

[OLDBULL8]

85_IDI_4x4

well you could probably bore the center out of the wrist pins then

Wrist pins are made out of Cold Rolled steel. The center is drilled out to a specific size, then that "pin" is run thru a carborizing furnace for a period of time to achieve a depth of .040 (IIRC) carbonization. While almost white hot they are dumped into a bath of hardening oil.

Now in order to drill the center hole out larger, it can be done with a solid carbide bit useing a lubricant such as the "gum of spearment".

But when doing that, it will upset (weaken) the integrity (shearing) strength, as you have removed the inner hardened shell.

 

[racer30]

Well I didnt Know they carbonized them.. That kind of kills that idea. I was thinking of puttin them in a lathe to drill them out with a carbide cutter but loosing the hardend surface wouldent be a good idea. Just seems to me Guys have been puttin turbos on non turbo rods without bending the 29mm rist pins, so taking a little out of the center of the 33mm pins sounded like a good place to remove some wieght...

 

[OLDBULL8]

Yup, they sure are carbonized. The heat treat furnace is fed from a Carbon Monoxide generator. A very tuff surface for wear, and inner core for strength.

 

[hairyboxnoogle]

Ive been working on getting around to see what we can use as far as rods and pistons out of a gasser to use in our rigs, but my guess is the rods will be to small / narrow. As for pistons. I was going to, but i really havent come across anyone ever having a specific piston failure. The thing about lightening the crank is 90% of the time you lighten something youre taking away from the strength of it. Also, if you lighten the crank, without lighter rods / pistons, you wont be able to balance the rot. ass. The weight in our engines doesnt necessarily make them the weak link at high rpms. Its alot heavier, thus its alot stronger. The big big engines you guys are talking about dont turn so low rpms based only on weight, but sheer size. They have something like 80' 2- piece rods for starters, with like a 22' stroke. Not to mention the way the fuel burns in such a large engine, it doesnt have to turn fast at all to be efficient. In fact the slower you can turn an engine, the less parasitic loss you have, and in something that big... every rpm is a very marginal amount.

As far as the 1200hp idi goes, i would say that it turned around 5-5500rpms. Hypermax told me that they used the origianal crank and rods that had been treated, and custom made pistons. The bottom end wasnt jello. The sheer power it made was causing the whole engine to flex. No doubt that much weight moving that fast made a difference. The whole reason for clearances in an engine are to accomadate for stretching and flexing at even normal operating ranges. This is the same reason why race engines have more strict, but often looser clearances than a factory engine.
After myself and a few others personally talking to a few aftermarket and machinist people, the weak link is the pump, as far as fueling that high and not coming apart, specifically the driveshaft in the pump. Finding a billet hardened shaft is in the works. I know local tractor pullers who run john deeres into the 4k range all the time pulling. Theyre built every bit as heavy as our engines and are strictly designed to run at 2200 and for all intensive purposes ONLY at 2200 rpms. Not to mention being an inline 6, they have a longer crank and alot longer stroke.

Personally, im confident that with the pump driveshaft issue taken care of, proper clearances, studs, girdle, balance, and blueprint. I will turn mine 4400 with no problems.

 

[bike-maker]

If you add weight to the rotates in the crank, and weld in bungs of mallory metal (which is considerablly heavier than regular cast iron or steel). This makes the cost of the balance job get expensive pretty quick.
If one were to lighten the rotating components, the weight could be removed from the crankshaft counterweights by drilling big ass holes in them, which is the easiest method of balancing a crank anyway.
All I am saying is, don't worry so much about using lighter components if you are going to have the rotating assembly balanced anyway; it would only add little cost in labor to rectify. I have had to knock even as much as 250 grams off the counterweights of a crankshaft to balance it.

 

[bike-maker]

I have personally done machine work on a couple IDI's, quite a few powerstrokes, and a hand full of older IH gasser engines; the common denominator is all of them have cranks and rods that are built hell for stout. I would trust them to spin 5000 rpm, but it might be a good idea to use a girdle on the main studs. It is sounding like block flex was the main problem in the infamous Hypermax engine.