I want theory.

So lay it on me. Is it merely the combo of parts?
What is the limiting factor, there has to be one?

Is it flat because at the beginning it is pulling the max power an engine flowing that much can do?

So seriously, theory, anything and everything!

Thanks guys, look forward to it!

 

This will answer most of your questions and maybe develop more.
http://www.n2performance.com/lectures/sample.pdf

yedi

 

Thanks Yedi!

How's the project coming?
Last I talked to you, I think you were aiming for a 434 to take down to the salt flats right?



So I geuss, I need some more dummy advice then.

If you have a torque curve that peaks at ~4200rpm and ramps up fairly quickly to that point. What can you do take that torque number and extend across a wider range of RPM?

 

Ok, this is what I want to achieve. Currently the motor makes 400rwtq at 4200, I wanna stretch it out across the RPM band...

 

I like that link! Its not my thread but I got a question about the article.

In the "Tuning Intake and Exhaust systems" section, the author talks about making headers and intake runners with different cross sectional areas to broaden the torque curve. I am not sure I completely understand this concept. Is the author suggesting make say intake runners for cylinder 3, 4, 5, and 6 one size and the rest another size?

 

Other than add cubic inches, you can't. If you want a broad, flat, torque curve, you are going to have to take some off of the top. Consider it as if you were working with dirt. With the size of the engine established, you can't just go out and buy fill dirt to build up the ends of the curve. You have to scrape some off the top of the mound, and spread it around, to level it off. From my observations, the flattest torque curves come from camshafts with wide LSAs. In other words you can make the curve, broad, flat, and more usable for most driving, but you will sacrifice your high peak for a high average.

RACE ON!!!

 

Ok, thats what I thought... lame!


I really like the analogy though!
Thanks CFI!

 

How can this dyno sheet realistically predict hp at 50 mph when the car is not fighting a 50 mph headwind sitting on the rollers???

 

USA
Generally, advancing a camshaft will increase low and mid-range torque at the expense of some top end power. You could try that with your current cam. Comparing you power to another engines power is worthless unless your components are relatively close to each other and both engines are dyno on the same dyno and the air temperature is close. Mix oranges with oranges.

My car should be done at the end of this month, with the tuning. Then paint and some interior work. Over the winter I have to get a different rearend. I thinking about a 9 inch independent and roll bars. I need them for the Maxton and Texas Mile. I will have to make some body modification to control airflow under, over and around the car also. 200 MPH is what I am shooting for.

But, the really good news is that I have all the parts for my 454 smallblock long block except the camshaft. It was going to be a twin turbo but for the amount of power that I want this motor to be capable of making (but will not use) with the rpm limitation set by me, the size of the turbos will not fit in the engine compartment. I am going to a blower setup.

Yes, from my conversation with Extrude Hone a few years back it is what a lot of car engine builder do since each port on a cylinder does not flow exactly the same amount of air for a given lift. By doing this it is possible to slow down or speed up the air velocity going to the heads since the intake feeds air and fuel to engine cylinder by way of the heads. It's over my head! I guess that is why on some intake specs they give the the port cross section and length.

Yedi

 

I was always impressed with this 383sbc from AFR's website
Details:
383 cid Small Block Chevy Package
AFR 195cc Street Heads
9.5 to 1 Compression
1 3/4” Headers
AFR FloPower RPM #5028 and 0-4779 750 cfm Holley Carb
Comp Cams Hydraulic Roller Cam #12-433-8
MSD Distributor 36° Timing
93° Octane Pump Gas


How's that for a flat torque curve

 

Yedi, first off.
SWEEEET! I better be seeing vids from when she is running!

Second, don't tempt me with that shortblock!!!!

Third, the comparison was merely used because I want to eventually have a torque curve like that. The numbers don't mean anything, I was just talking shape. That torque just looks like it would be a blast on the street.

Here is the thing, my cam right now is at max lift 496/520. Continue on and see my head flow numbers. My 383 stroker I think has a TON of potential in just a cam swap. Maybe that is just me, but I think it is the case. (Let me know now if you disagree, trust me I want your opinion on this) In my case, I really don't want to see 600hp, what I do want, is a flat torque curve from 2000-5000 rpm of ~400lb/ft. I would be completely happy with that, and the rest of my car hopefully will be too!


SmokedTires ME LIKEY!
See here is the thing, I am running mildly Ported Dart 200cc's that outflow the AFR 195 Street heads up top and are VERY similar with low lift numbers:

AFR 195 Street:
LIFT---.200.....300......400.....500....600
Intake--132.....198......240.....260....262
Exhaust-108.....156.....178.....190.....194

My Darts:
LIFT---.200.....300......400.....500....600
Intake--138.....197......240.....268....283
Exhaust-101.....152.....183.....206.....210


Now looking at that, is what makes me think there is a ton of potential left. The cam in the car, I think, is way too small for the numbers it could be putting down.

Anyway, feel free to correct my error here if my logic is not correct.


Also if anyone has acess to DD2000, I would be curious to see what the cam mentioned above would be like in my motor.
-LPE SuperRam (portmatched and matched to a 1205 on the intake)
-Dart Heads listed above
-383 cid
-LPE longtubes out to a 2.5" Y-pipe, to 3" center pipe to 2.5" Magnaflow exhaust (basically glass pack muffleres)

 

If those heads actually flow those numbers I would go to a solid roller. My XR280R has over .600 lift and I think this cam is reason for my rather flat torque curve.

You may have already seen this as I a posted it in a thread below, but if you haven't here it is and yes it is a blast to drive on the street, nothing I have ever driven compares to it :

 

this is a dumb answer.

but turbos flatten out the torque curve to no end.

 

Wow that is what I am talking about!

400rwtq just straight across. Man it must be a BLAST!

I don't know if I would really want to go to a soild roller though....

I am debating talking to one of those engine design guys. You know the ones that will design the right camshaft for your motor/combo. Anybody know of one or have done this before?



Oh and the heads definitly flow this, not mag numbers either!
http://www.azzatochips.com/DaveE/scan.pdf

 

Not a dumb answer. I was thinking more along the lines of a twin screw supercharger but either way....way too much $$$!

 

I ran three different rollers cams in my 11.2 383 with big valve & ported 215's which cc at 221 cc and later Dart 227cc heads. Both of these heads were over 300 cfm @.600 and @230 cfm ex.

The first cam was a Crane 232/238 112 Really impressed the first time out in it after the breakin period.

I'm kind of into racing so I had a extreeme ramp 240/248 112 .635/.644 custom cam made. It had lots of top end power right into my 7500 rpm rev limiter. it ended up beating it's self and my lifter to death. I then jumped over to a comp cams custom billet 236/244 again 112 and no ground in advance. so in effect it was like it was installed 4 degrees retarded. This was a real flat TQ all the way to 7500. I still have it in the complete motor in a box. I'm going to advance the cam 4 degrees and it might really be something then.

I posted pictures of these three cams just in another thread on this part of the forum. Your smaller heads would like the bigger two of these cams.

 

Hmmm, does that still apply if the red line will be around 5200-5500. And I don't mean redline, but I mean, the LPE SuperRam Intake I think will probably be dropping off around that time.

I have been playing around a bit with EngineAnalyzer by performance trends, free trial. Thing is, my setup is not putting out the same numbers as it did on the dyno in real life. Also, I am waiting for TJWong to send me a copy of my dyno sheet so I can compare and move from there.

How does a soild roller cause the torque curve to be flatter?

 

You just input the Cd (drag coefficient), the frontal area, barometric pressure, temperature, and humidity, then it is all math from there (the formula for drag power versus speed is in any good automotive handbook).

In other words, that figure of 11.5 hp isn't measured on a dyno. It is the amount of power calculated to be required to drive that car through the air at 50 MPH. Doesn't require much does it? A riding lawnmower engine could push the C6 through the air at 50 MPH, though it might take a long time to get to 50 MPH.

 

I know how it can be done, I just fail to believe that the tech had accurate data (and entered it) as to such things as Cd and frontal area for the Vette.

 

Still wondering about the solid roller =flat torque curve effect...


Hey Motorhead, I can't find the specs for that cam anywhere. You got em?

Also, you are running 1.6s right?