pushing the evelope of the 3500

[Driver_10]

Keoki1978. Ill put aside the petty insults for now and lay out my logic behind my choice of engine configuration.

As anyone well knows, engine power is directly relative the coefficient of the amount of air that an engine can breath to each two revolutions, or 4-strokes, of crank travel at any given time of engine operation. Logic would dictate that an increase in engine rpms would allow for more overall power to be produced.

The problem arrises when the torsional limits of the connecting rods and bolts are exceeded by the inertia generated by the sudden halt of motion at TDC. The "Piston travel speed" is directly controlled by diameter of the stroke. A shorter stroke allows a slower the piston speed coefficient. This gives the engine a higher "safe" rpm limit to operate in.

A full, race-built, 1/4 mile drag car will run piston speeds as high as 5200-5500 in short burst. A 1000hp, 12,000rpm, "Indy-car" engine will run sustainably no higher than 4300-4500 ft/min. Your average street-driven hot-rod with good components will run piston-speeds of about 4000-4200.


(Using 4200 rpms) The formula for engine RPM as determined by stroke is as such

(Max ft/per min x 6)
engine stroke

= max rpm

(4200 ft/min x 6)
3.31

= 7613 rpms max (absolute red-line)

Another factor to think about is rod angularity. Rod angularity is the angle of the rod to the pistin pin. An engine with high rod angularity will produce more torque. This however, come with a price.

Because of the increased thrust against the walls of the cylinders, the engine will ultimately suffer a shorter lifespan from wear. It will also suffer a greater frictional losses as a result. Busch series race motors have extremely small because of this fact. Smaller stroke travel and increased rod-ratio will use combustion energy better and increase rod-bearing lifespan due to less physical movement of the crank-pin within the bearing.

Shorter stroke will also allow the use of longer rods without compromising piston compression-height as well. This will keep the piston at TDC dwell longer and promote better combustion efficiency and increase overall thermomechanical efficiency (conversion of heat energy to mechanical energy) . This will also help to fight detonation due to the fact that the end-gasses will cool longer in the quench while dwelling at TDC for more controlled combustion. (This translates to more sprak advance and better efficiency at crusing)

Ill use my 2 most recent engines as a good example. Both hava a similar 3.4l of displacement and both have the same piston compression hieght. (around 204-207 CU and 1.4600 CH). Well simplify VE variables and just say that they're both turbocharged. My first engine has a larger stroke of 3.31 with shorter rod (5.700). My second engine has a smaller stroke with a longer rod (5.850). The one Im building now.

3.31 stroke @ 7613rpm (4200ft/min)
3.192 stroke @ 7894rpm (4200ft/min)

My new motor with the shorter stroke will be able to produce more power, higher rpms and have a better rod ratio despite similar displacement to the greater stroked motor. As an added bonus, ill have greater mechanical efficiency, more detonation resitance and longer engine life.

[Keoki1978]

CNC'd heads are the way to go. That company does a good job with their work. We've used them several times. Big difference in hp than off the shelf parts. And just to let everyone know, I'm not trying to say that mine is better than your's. I havent even told you guys what I have other than the FAST engine management system and a flat tappet cam. But I got a big laugh when I saw the "de-strokeing", "hardcore", and "pushing the envolope" all used in the same paragraph. I never said any of those for my build. I call mine "the shit build" cause I'm hoping that I'll be in the 300hp range with most of my power in the upper end for autocross racing down in palm beach. And believe me, I spent 90% of my money in the heads. Ultra lite weight rods and pistons along with the aluminum flywheel all play a big role in my build. I wont tell you, but there is a major manufacturer that produces a sweat aluminum flywheel that bolts right up, weighs 7 pounds and isnt even meant for our engines, but it bolts on. Oh, and at less than 200, its a steal.

What good is CNC copying a non researched port design?>> Actually, they must have some R&D going on. The as cast dart heads on a 11-1 comp 355ci made just under 500hp. Those same heads after cnc'd on the same motor, customer wanted to break it in and get a feel for it, then made almost 550hp with no other changes.

[SappySE107]

What good is CNC copying a non researched port design?

Forced, that is spark induced detonation, not dynamic compression which will create detonation at any RPM. Spark is based on bore/stroke as much as RPM.

[ForcedFirebird]

Hogwash


Ever heard of Darin Morgan?

Here's a quote for ya'....

P.S ,,,,,If someone says that they lost a tenth of a second because they changed the rod from a 5.7" to a 6" , that is just silliness of the highest order! This is how all these rumors get started. I can tell you with 100% certainty, beyond all doubt what so ever, that if someone found a tenth difference from a 5.7" to a 6", they had many other things wrong that led them to believe that. The rod ratio had absolutely nothing to do with it what so ever.

And if you think rod ratio, stroke and RPM have nothing to do with each other, then look no further than the F1 motors with their EXTREMELY over square engines.

keoki, whatever you built that's cool, we all have a resume, but this is a tech site for the 60 degree v6. We are a community here and got something going. If you ant to play the "I'm better than you" game go post on a 3800 forum.

A little trivia...

At what RPM does detonation NOT become an issue?

What's the mean piston speed in your engine at 8000rpm, rod deflection, cylinder filling, velocity, flame speed or flame pattern for that matter? What was the difference of the bore rod angle from the 5.7" to 6" rods ATDC, and what's the difference in piston travel in that time?

EDIT: I can guaranty you that the only reason you gained on the longer rods is because of less frictional losses. Longer rods DO NOT make more power, but rather reflect the operating RPM range.

Is what I think you are NOT getting is John (Driver) is taking off-the-shelf parts and making a 500+hp v6.

I am one of two here that OWN a CNC shop, why would we outsource to get CNC'd heads/manifolds?

[Keoki1978]

Dont worry about it Ben. I actually like guys like him. The'yre fun to mess with. Like I said, I have a natural pension for starting thread fights with dumb people

Ignorance + lack of mathmatical skill + IQ of "jar of mayonese" = THIS GUY!

more fun for me

Whatever guys. My experience building motors for the last 15 years, I've never herd of guys talk about de-stroking just for high RPM's. My experience with most engines happens to be based around your typical run of the mill 350's. We've never had a problem spinning these motors out to some insane RPM's for their size while making power all the way up till valve float. I've been involved with building a chevy 406 that ran up to 8500RPM's all day long. We built a guy a 454 SMALL BLOCK cause he wanted it so bad, with a solid roller cam, hes revving up to 7500. Most of the time we are using the FAST engine managment systems which are just below the electromotive tec 3 but light years ahead of that mega squirt system. The shop I work for laughed their asses off when I showed them all this this morning. But with the 3x00 V6's, I took what works very well in most V8's and applied it to my motor. The long rod theory is just a theory in my opinion. On a dyno with a 383, one had a 6 inch rod, the other had a 5.7 inch rod. Yes the longer rod motor made more power, like 2 hp more and had made the power at a higher rpm, like 100 rpm higher. So is it worth investing all that time and money to make power just 100 rpm's higher and like 2-5 hp more?? I dont. I'd take that money and put it into something that makes more sense. Besides, these tranny's in the FWD are geared differently, but RWD you might be on to something. If you ever looked at motors in general, you'll see that the power is made from the heads. Thats where I'd invest all the money in the world on first. Check out M2 Racing. They do CNC heads, they will do ours also if someone wanted to invest the time and money for them to gear up to produce them. So take your de-stroked 3500 and let me use it as my boat achor, cause I need a new one...

[Driver_10]

(Update

My block will be shipping soon and I have the parts assembled for the final short-block. Big thanks to John (Forced_firebird) and Ben (Sappyse) for help in parts selection and research help.

I will keep a photo journal from week to week of the build starting when the block arrives!

[Driver_10]

Thanks everyone for the help. I feel a bit more confident in the bottom-end potential of this block.

Oh yeah, and thank you Keoki1987... I needed a good laugh. (side note) You may want learn up a bit more before dropping your "2-cents" as you put it. Reading "turbo tuner" and "hot-rod" magazine does not substitute for actuall scientific understanding (nor mathmatical inclination in your case)

Let me know how those 6-inch titanium rods work out for ya.

[ForcedFirebird]

[Driver_10]

Ill point you in a better direction. You can take your bullshit somewhere else.

Dont worry about it Ben. I actually like guys like him. The'yre fun to mess with. Like I said, I have a natural pension for starting thread fights with dumb people

Ignorance + lack of mathmatical skill + IQ of "jar of mayonese" = THIS GUY!

more fun for me

[Driver_10]

Im sure that I could hitch up some magical unicorns to the front of the car and rub it with cheetah blood to go the speed of light too.



So your determined to build a 3400 out of a 3500. Damn dog, just thought that if you wanted to build a HARDCORE 3500, why not just build a 3500. Why mess with destroking, oh yeah, that few extra rpm is gonna kill them hondas running round in miami right. If you didnt want other peoples opinion, then you 2 should of keep this off the net and between the 2 of you on the phone. In my opinion, your not pushing no envolope or building a hardcore 3500, your simply screwing up a good motor.

Damn.....Dog?

Whaaat? you dont like unicorns?

[SappySE107]

Anyway, just wanted to point you in a better dirrection...

Ill point you in a better direction. You can take your bullshit somewhere else.

[Keoki1978]

Im sure that I could hitch up some magical unicorns to the front of the car and rub it with cheetah blood to go the speed of light too.



So your determined to build a 3400 out of a 3500. Damn dog, just thought that if you wanted to build a HARDCORE 3500, why not just build a 3500. Why mess with destroking, oh yeah, that few extra rpm is gonna kill them hondas running round in miami right. If you didnt want other peoples opinion, then you 2 should of keep this off the net and between the 2 of you on the phone. In my opinion, your not pushing no envolope or building a hardcore 3500, your simply screwing up a good motor.

[Driver_10]

I just think you guys are trying to much with all that. If I had the money to build what I described, that would be the motor to build. Save the money your gonna spend on destroking that crank, put that with the money for the rods, get some lite weight titanium rods in a 6 inch length, some lite weight pistons, fab up a sheet metal intake, search for a shop that has cnc capabilities to cnc the chambers and port match the intake side, then get some titanium valves and retainers, a solid roller cam, forget the mega squirt, get the Electromotive Tec 3, its already got its own coils. I garrantee you that motor will spin to whatever rpm you want and keep making power till the bottom end falls out. I've been involved with a few builds, mostly 350 GM's, stroke em out to 3.75" on a 4.125" bore, and these are revving to almost 9grand. That mega squirt thing is entry level shiznit, would of never made it to where it is now if it wasnt for people trying to be cheap. I'm running a FAST bank to bank system on a turbo 3100. Hydralic flat tappet cam specs say engine should run to the 6900RPM's and start making power above 3000. But I'll believe it when I see it. Anyway, just wanted to put my 2 cents in and trying to point you in a better dirrection...

Im sure that I could hitch up some magical unicorns to the front of the car and rub it with cheetah blood and go the speed of light too.

[Keoki1978]

I just think you guys are trying to much with all that. If I had the money to build what I described, that would be the motor to build. Save the money your gonna spend on destroking that crank, put that with the money for the rods, get some lite weight titanium rods in a 6 inch length, some lite weight pistons, fab up a sheet metal intake, search for a shop that has cnc capabilities to cnc the chambers and port match the intake side, then get some titanium valves and retainers, a solid roller cam, forget the mega squirt, get the Electromotive Tec 3, its already got its own coils. I garrantee you that motor will spin to whatever rpm you want and keep making power till the bottom end falls out. I've been involved with a few builds, mostly 350 GM's, stroke em out to 3.75" on a 4.125" bore, and these are revving to almost 9grand. That mega squirt thing is entry level shiznit, would of never made it to where it is now if it wasnt for people trying to be cheap. I'm running a FAST bank to bank system on a turbo 3100. Hydralic flat tappet cam specs say engine should run to the 6900RPM's and start making power above 3000. But I'll believe it when I see it. Anyway, just wanted to put my 2 cents in and trying to point you in a better dirrection...

[Driver_10]

It was all just a BS thing, I'd love to build a stroker 3500 to a 3700 with titanium rods, billet steel crank. I didnt do the math but your right, I couldnt use 5.850 length rods with a 1.460 comp height and a 3.504 inch stroke. But I suppose I'd be able to use a 6 inch rod with a 1.154 comp height pistons. Anyway, I'm in tampa area by the airport, or town n country area for those that know the area..

I figured as much. The outlandish stroke was the first dead give away The "smarmy" attitude was the second.

I figured that Id ask the questions to put ya on the spot. (photos, numbers etc.)That way if there was a lagitimate mistake or typo, it woulndt have to start another thread fight. You never know when there may have been some genuine honesty in a statement. (Ive had a pension for pissing people off lately)

In any case, I appriciate the honesty.