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.alex.
Dodge Dakota
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11/19/2002
09:59:33
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 Subject: KRC Street Cams
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The dyno numbers are up at the site.
www.krcperformance.com
12-14 hp and 18-22 tq OVER the HO cams!
mmmmmmm........
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cudashoe
DakotaEnthusiast
11/19/2002
10:43:10
|  RE: KRC Street Cams
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Your making me spend more money!!!!!
2000 4.7 5- speed, 1989 Shelby #799 White
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.alex.
Dodge Dakota
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11/19/2002
11:06:33
| RE: KRC Street Cams
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Hell, he's making me spend it too!!!
What the hell am I supposed to do?
;)
I was supposed to not ever mod this truck, save up and buy a GEn II truck and make THAT one the fast one. Oh well.
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Canucker
Dodge Dakota
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11/19/2002
11:15:45
| RE: KRC Street Cams
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Damn, that rocks!!
If you read close too, he mentions the TQ peaks at 3300RPM! ... That's about 100RPM above where the stock peak is. I was expecting that to be more around the 4000RPM range.
heck, that's a lower peak than the HOcam/intake combo.
And here everyone was worried about a loss in low end power. I really, REALLY hope he posts a pic of the dyno sheet when he gets some final numbers done.
hmmmm ... and just in time for Christmas.
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Chris
Dodge Dakota
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11/19/2002
12:13:24
| RE: KRC Street Cams
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Now how do I hide $600 from my wife... $250 was easy....
Does the HO intake manifold really help though? I am going to swap mine back in the spring... Maybe do it on the Dyno....
What manifold on the truck with these gains?
Chris
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.alex.
Dodge Dakota
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11/19/2002
13:24:02
| RE: KRC Street Cams
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Apparently the stock intake manifold was used in this dyno run.
The only difference in the manifolds is how long the runners are. The HO manifold has shorter runners and helps power development up in the 3500-5500 rpm range. KRC will be releasing one with even shorter runners to make serious power up in the 3500-7000 rpm range. They already have a 500 hp naturally aspirated 4.7L motor that they are still tweaking on.
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Chris
Dodge Dakota
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11/19/2002
13:40:20
| RE: KRC Street Cams
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Alex,
Don't the shorter runners move both the HP and Torque up in the RPM's. That is what I was getting at with the note about where the tq peak occurs. I would also like to see a longer runner version to make a real torque monster out of this thing. Prove that SOHC is the way to go.
Chris
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.alex.
Dodge Dakota
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11/19/2002
13:56:40
| RE: KRC Street Cams
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They move the PEAK torque numbers up higher which in turn produce higher horsepower numbers. It's just a math equation. To make serious torque on a motor this small you need forced induction. To make serious torque on any motor, you need more cubes. Look at Cadillac. They had 500ci motors all the way thru the 60 and 70's into the early 80's. They wouldn't rev for sh!t, but they could make a 5000 lb car fly like a plane.
The whole deal behind these 408 stroker motors is they don't rev. They don't have to, since they have so much displacement.
The way to make big naturally aspirated power out of a small motor like the 4.7L is to rev the hell out of it. I've been e-mailing Marty a lot, and he'll say the same thing. You just have to be willing to wind it up.
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kicker01
Dodge Dakota
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11/19/2002
14:01:26
| RE: KRC Street Cams
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Ill expect these numbers to be alot better without the precats and a flashed PCM.
Steve
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Chris
Dodge Dakota
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11/19/2002
14:11:47
| RE: KRC Street Cams
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Alex,
I agree with you on making power, to do that you have to rev. To make torque you do not want to. I jsut think we could make a 400 lb-ft @ 2800 RPM torque monster or a 300HP @5500 rpm engine out of this 4.7 with no problem... just based on how it reacts with these simple HO mods. Either the HO manifold or Marty's manifold should further wake up these cams for sure.
Chris
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.alex.
Dodge Dakota
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11/19/2002
14:26:20
| RE: KRC Street Cams
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Steve, they will be better. I made 233/301 with no precats and a Leach flash and pretty much your same mods and that was with the HO cams & intkae manifold. I think you may see 240 to 250 rwhp with the flash and headers.
Chris, all i can say is ... keep an eye out over at www.krcperformance.com and we'll find out.
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Canucker
Dodge Dakota
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11/19/2002
16:17:22
| RE: KRC Street Cams
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Chris: Torque is the result of one thing: Cylinder pressure (assuming an ideal A/F ratio, timing, etc.).
i.e. in N/A form, a 4.7L displacement engine is physically limited to a certain amount of torque due to the amount of air that can get into the cylinder. ... a perfectly designed N/A engine will have a 100% flat torque curve with a VE well over 100% the whole way... this is done through variable intake geometry, variable valve timing, variable valve actuation (2 valves vs 4), variable throttle diameter (to my knowledge, never been done), etc etc and variable everything on the exhaust too. Has anyone ever made the perfect engine? no. too expensive.
So for our engines, and most engines, you have to trade off where you want your peak volumetric efficiency and torque. I'd guess that the most torque you can sqeeze out of this engine with its present compression ratio is 375ft-lbs without forced induction, maybe 400ft-lbs. I have yet to see any with a significant amount more than 300ft-lbs at the wheels. But to get 375-400ft-lbs, you'd have to design every part to operate at a specific RPM, and then you'd have a torque curve that looks like Mount Everest. ... i.e. you'd have to design the valve lift, duration, overlap, the intake runner length and diameter, the plenum volume, the TB size, the valve size, the head runner sizes, the header tube length and diameters etc etc etc... to operate at a single RPM.
Is it possible? probably. would you want to do it? probably not. DC did a pretty good job at sqeezing as much TQ out of this engine as they did (they had 'truck engine' in mind when they started designing)... the most we can really do is pic where we want the TQ, and maybe get a little more out of it. So if you want your peak 350ft-lbs to fall at 4000RPM .. then you're making almost 270hp. If you want it at 5000RPM, you're making 333hp. Once you get into the higher RPMs though, you are limited to what a 2 valve head can do. It can only flow so much air before it starts becoming the bottle neck.
Its all about torque. HP is just a derivative of TQ and doesn't really matter.
wholly fuk that was waaaay longer than I expected it to be. I hope it made sense, cause I tend not to make much sense at times
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.alex.
Dodge Dakota
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11/19/2002
16:23:49
| RE: KRC Street Cams
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yeah.... that's what I was trying to say.
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