383 bolt-ons/Desktop Dyno Sim

[cougs]

All,
I've been playing around with desktop dyno a bit.  Starting with a stock '68 383 Magnum with 10:1 compression, stock stall, and 3.23 gears (going to 3.73 in a month or so) and adding the following:

- DP4B Edelbrock intake
- Proform 750 CFM Carb (rec'd by Ron)
- TTi 1 7/8 headers, 3" pipes
- Hughes HMC2942BL Whiplash cam 229/242 at .050 .518/518 107 CL

I was originally considering going with a milder cam upgrade and keeping the H.P. manifolds but the speed bug got me! 

Anyway, I'm having a difficult time deciding on a cam.  The whiplash has a mean idle and is a slight step up, performance wise, over the 268/284 adv .450/.458 stock cam.  If I go any more aggressive, it kills the torque and only maintains the horsepower. 

Anybody have any cam recommendations to put into the simulation?  I'd like to get to 425 hp w/o giving up a lot of torque and I'd like to maintain my stock torque converter.

[XH29N0G]

I'll let others respond to this.  I think the bore and stroke are different than what you used (I thought they were 4.25 and 3.375 (I hope I did not misread the image- there was an RB version from the late 50's that I think has the numbers you list, but the low B version 383 from the late 60's has a shorter stroke).  This will have an impact on the torque, which my   are that I would work to that with the 383.  Other than that, I do not know how realistic (in absolute terms) the dyno programs are.  I assume if they match the build they have the potential to be realistic, but that depends a lot on who builds the engine and what the parameters are that go into the calculation.

[cougs]

Crap, you're right, I picked the wrong 383!  I'll change it and send a new shot. 

[cougs]

OK, so it appears that now that I've selected the right bore and stroke the engine is performing better. 

Any feedback??  Can I squeeze a little more out of it with a different cam?

[A383Wing]

I got basically the same program on my computer, when I was using this, I chose what RPM I was going to be running at most of the time...then had a cam ground for those specs...

few years later, I took the car to a dyno and ran it....readings from computer dyno and real dyno were pretty accurate to each other

[cdr]

that is WAY off, look at the torque. not out of a 383 !!

[fy469rtse]

I'm with CDR on this, alloy heads ? , you will have more chance with using single plane manifold similar to the the Holley torque 2 I think I used, I went with comps range HE range, but wished I went with hydraulic roller,
That simulator looks wrong ,

[Cooter]

Almost identical torque readings with same cam as the small block Chevy 383 up top.
and thats with 3.750 stroke.
A good reference for build, but wouldn't count on a simulator. Any more HP and your either gonna have to increase the cylinder heads/cam/rpm range.
I recommend you stroke it out.

[cougs]

Almost identical torque readings with same cam as the small block Chevy 383 up top.
and thats with 3.750 stroke.
A good reference for build, but wouldn't count on a simulator. Any more HP and your either gonna have to increase the cylinder heads/cam/rpm range.
I recommend you stroke it out.

That's where I'm leaning.  I could get this torque out of a stroker for sure. 

[cudaken]

Cougs, if it is not to much trouble could do a test using old MP Hemi 284 BB cam and the 509 cam with a troker intake?

that is WAY off, look at the torque. not out of a 383 !!

Why's that CDR? Stock they had 425 foot pounds.

Cuda Ken

[firefighter3931]

In that engine combination i'd run this Lunati Cam :

http://www.lunatipower.com/Product.aspx?id=1578&gid=362

I recommended that one to Jackson who has a very similar 383 build to yours....see below for results 

http://www.youtube.com/watch?v=BAWpWcgqX6w


Ron

[cougs]

Cougs, if it is not to much trouble could do a test using old MP Hemi 284 BB cam and the 509 cam with a troker intake?

that is WAY off, look at the torque. not out of a 383 !!

Why's that CDR? Stock they had 425 foot pounds.

Cuda Ken

Ken,
Send me the cam specs with intake centerline and I'll run it. 

Here a comparison between stock and this combo.  The sim says a stock 383 HP should do 420 ft/lbs at around 3,500 and 330hp at around 5,000. This isn't far off at all...at least for this combo.  This is fun to play around with, but I agree, experience and real-world use will trump this any day!!

[cougs]

In that engine combination i'd run this Lunati Cam :

http://www.lunatipower.com/Product.aspx?id=1578&gid=362

I recommended that one to Jackson who has a very similar 383 build to yours....see below for results 

http://www.youtube.com/watch?v=BAWpWcgqX6w


Ron

Ron, I ran this cam and the power was better all the way to 4,500 RPM!  After that, the Hughes Whiplash did better.  Brings up a big question.  The VooDoo cam seems to produce more total power throughout the RPM range (more area under the curve) which should make the car faster, right? 

Jackson's car sounds great!

Thx,
Brock

[1974dodgecharger]

Is that program to the wheels or engine fly.  Makes u all happy inside that it gives u such high numbers....then u get on a dyno and cry 

[cougs]

Is that program to the wheels or engine fly.  Makes u all happy inside that it gives u such high numbers....then u get on a dyno and cry 

Flywheel.......gross hp.  Doesn't even take accessories like water pump and alternator into account.

[A383Wing]

Is that program to the wheels or engine fly.  Makes u all happy inside that it gives u such high numbers....then u get on a dyno and cry 

Flywheel.......gross hp.  Doesn't even take accessories like water pump and alternator into account.

yes, at flywheel

[cudaken]

Cougs, here are the specks for the cams I asked about.

MP P4120235 duration 282/284  @0.050 241/241 Over Lap 68 Center Line 108 lift .484/.484

MP P4120237 duration 292/292  @0.050 248/248 Over Lap 76 Center Line 108 lift .509/.509

I know they are really old design's but I like to see how they compare to the newer cams. I have ran the first one a couple of times and really liked it.

Thanks in advances!

                  Cuda Ken

[1974dodgecharger]

Is that program to the wheels or engine fly.  Makes u all happy inside that it gives u such high numbers....then u get on a dyno and cry 

Flywheel.......gross hp.  Doesn't even take accessories like water pump and alternator into account.

Sweet.....

[BSB67]

Gross, corrected flywheel hp.

[BSB67]

Cougs, if it is not to much trouble could do a test using old MP Hemi 284 BB cam and the 509 cam with a troker intake?

that is WAY off, look at the torque. not out of a 383 !!

Why's that CDR? Stock they had 425 foot pounds.

Cuda Ken

Ken,
Send me the cam specs with intake centerline and I'll run it. 

Here a comparison between stock and this combo.  The sim says a stock 383 HP should do 420 ft/lbs at around 3,500 and 330hp at around 5,000. This isn't far off at all...at least for this combo.  This is fun to play around with, but I agree, experience and real-world use will trump this any day!!

The factory hp rating was a little optimistic.

[firefighter3931]

In that engine combination i'd run this Lunati Cam :

http://www.lunatipower.com/Product.aspx?id=1578&gid=362

I recommended that one to Jackson who has a very similar 383 build to yours....see below for results 

http://www.youtube.com/watch?v=BAWpWcgqX6w


Ron

Ron, I ran this cam and the power was better all the way to 4,500 RPM!  After that, the Hughes Whiplash did better.  Brings up a big question.  The VooDoo cam seems to produce more total power throughout the RPM range (more area under the curve) which should make the car faster, right? 

Jackson's car sounds great!

Thx,
Brock

Brock,

I'll take a cam that produces better bottom end & midrange power vs the one that produces the best peak number anytime. The car will accelerate harder and have better throttle response. When racing it's the first few hundred feet that are the most critical. 

Try re-doing the program and plug in 9:1 compression and see what happens. The factory 10:1 ratio was overly optimistic and the real/actual number is closer to 9:1. A cam with 229@.050 intake duration is going to be less than ideal with 383 cubes using a stock converter, inmo. With a short stroke 383 in a heavy street car with modest stall you want to maximize torque to get that beast launched and accelerating.   



Ron

[cougs]

Cougs, here are the specks for the cams I asked about.

MP P4120235 duration 282/284  @0.050 241/241 Over Lap 68 Center Line 108 lift .484/.484

MP P4120237 duration 292/292  @0.050 248/248 Over Lap 76 Center Line 108 lift .509/.509

I know they are really old design's but I like to see how they compare to the newer cams. I have ran the first one a couple of times and really liked it.

Thanks in advances!

                  Cuda Ken

Ken, PM me your email and I'll send these over

[cougs]

In that engine combination i'd run this Lunati Cam :

http://www.lunatipower.com/Product.aspx?id=1578&gid=362

I recommended that one to Jackson who has a very similar 383 build to yours....see below for results 

http://www.youtube.com/watch?v=BAWpWcgqX6w


Ron

Ron, I ran this cam and the power was better all the way to 4,500 RPM!  After that, the Hughes Whiplash did better.  Brings up a big question.  The VooDoo cam seems to produce more total power throughout the RPM range (more area under the curve) which should make the car faster, right? 

Jackson's car sounds great!

Thx,
Brock

Brock,

I'll take a cam that produces better bottom end & midrange power vs the one that produces the best peak number anytime. The car will accelerate harder and have better throttle response. When racing it's the first few hundred feet that are the most critical. 

Try re-doing the program and plug in 9:1 compression and see what happens. The factory 10:1 ratio was overly optimistic and the real/actual number is closer to 9:1. A cam with 229@.050 intake duration is going to be less than ideal with 383 cubes using a stock converter, inmo. With a short stroke 383 in a heavy street car with modest stall you want to maximize torque to get that beast launched and accelerating.   



Ron

Ron,
Thanks. Good point. The last thing I want is a sluggish launch. Adjusting to 9:1 compression reduced torque by about 15 ft/lbs across the whole band   

I have another question.  What do you think of the 268/284 .450/.458 Stock Magnum cam?  I know it's a 45 year old design but with its duration is *should* make decent power (at least according to the simulation).  This is what I have now.  The problem I have with it is that it doesn't lope like I would like and doesn't have the top end I'm looking for, but it does launch the car!  Are the specs on the stock cam again, a little exaggerated?  It seems to not lope and have a lot of low end which is surprising due to the duration.  

[firefighter3931]

Brock,

The stock Magnum cam works well for what it is but with a small overlap the idle is pretty sedate. Duration is short which helps build bottom end power and torque. The lunati is 3* tighter on the LSA (112 vs 115) and has another 14* duration at .050 valve lift so it should pull better up top. The increased valve lift won't hurt either. That is a faster lobe than the factory cam so it will make more power.  

I'd like to see it compared to the 262 VooDoo on the same graph  

Oh ya, it'll definately have a more agressive sound at idle  



Ron


Ps. While you're playing around with the dyno sym try inputting small tube header just to see what that does to the torque number. A 1 7/8 header is a bit big on a mild pump gas 383 and it will hurt torque. The ideal size would be 1 3/4 but i understand your reasoning.....stroker coming in the future. I was in the same boat when i purchased the TTI's and bought something that was a little too big in preperation for a future build.

[cougs]

Brock,

The stock Magnum cam works well for what it is but with a small overlap the idle is pretty sedate. Duration is short which helps build bottom end power and torque. The lunati is 3* tighter on the LSA (112 vs 115) and has another 14* duration at .050 valve lift so it should pull better up top. The increased valve lift won't hurt either. That is a faster lobe than the factory cam so it will make more power.  

I'd like to see it compared to the 262 VooDoo on the same graph  

Oh ya, it'll definately have a more agressive sound at idle  



Ron


Ps. While you're playing around with the dyno sym try inputting small tube header just to see what that does to the torque number. A 1 7/8 header is a bit big on a mild pump gas 383 and it will hurt torque. The ideal size would be 1 3/4 but i understand your reasoning.....stroker coming in the future. I was in the same boat when i purchased the TTI's and bought something that was a little too big in preperation for a future build.

Ron,
Here's the VooDoo vs the Magnum.  Note that the VooDoo is installed on 108 ICL and the Magnum is on a 113 ICL.  The darker line is the Magnum cam.  I changed the sim to a 650 CFM carb, 9.2:1 compression, and small tube headers.   The 750 carb was doing very little.  The large headers didn't appear to hurt torque much but I agree it was overkill for a mild 383. Also, I'm running a FirmFeel pitman arm and idler arm which won't work with the 1 7/8" headers
Let me know what you think!