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Analyze my combo and dyno graph!

5K views 26 replies 14 participants last post by  429TORQ 
#1 · (Edited)
Hey guys. Long time member, rare poster. I'm the guy with the 460 Crown Vic. We got this dyno on Friday and I'd like opinions! I have a couple of questions, after the picture.

First, my combo:

1983 460 Short Block bored .40 over
1983 OE spec pistons & rods
1968 C8 Ford Heads, home ported as per Scott J.'s website
factory '68 valve train w/locking nuts
Custom cam per Scott's design - .492 Intake lift, .523 exhaust lift, 217.7 intake duration, 230.1 exhaust duration
Adjustable roller timing chain set to o*
Stock 83 Ford truck water pump
Stock 83 Ford truck (4x4) oil pan
Edelbrock Performer Aluminum Intake
Holley Street Avenger 770 w/ 72/72 jets
Dura Spark distributor w/Scott's advance curve 14* initial timing.
Mallory Hy-Fire VI-AL ignition box
Mid length tubular headers headers from Fordpowertrain.com (Shorty II's)
True dual exhaust with straight pipes, custom H. 2.5" Dynomax Super Turbo mufflers, to side exit exhaust.

Mallory 4110, 110 GPH electric fuel pump, dead headed and self regulating at 7 psi.

31x19 Aluminum Radiator
160* Thermostat
1995 Taurus electric cooling fan and shroud
PSM variable fan controller

'78 Lincoln C6 Transmission with "F" apply servo
'78 Lincoln factory stall converter

Dyno image here:

http://forums.corral.net/photopost/showfull.php?photo=67290

My dyno simulations all show this combo should make peak horsepower at 6000 RPM. Any idea why it would be peaking at 4500?

Any other suggestions, questions or recommendations?
 
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#4 ·
1. Chassis dyno's and engine dyno's will have totally different curves.
a. Road drag, (tire contact), increases as speed rises.
b. Driveline parasitic losses become logrythmicly more as speed rises
2. Dyno SIMULATIONS are rarely correct in the first place.
 
#5 ·
carb, intake,cam,and some other things need to go
 
#8 ·
I believe it weighed in a 4050 with me in it. Best quarter mile time was 14.3 at 97 MPH.

RMCOMPRANDY - Are you suggesting that the dyno graph looks "right" to you?

BOSS 429 - Why do those things need to go? What are you proposing?

From everything I can find to read, the carb is properly sized. The A/F ratio on the dyno shows that it's running rich, if anything. Do you think that's because the carb flows plenty of fuel, but not enough air?

Ultimately, I would like to make this combo run as best as possible. In the future I plan to turbo or supercharge the current ingredients and try to make close to 500 RWHP.

I know that the compression ratio is not optimal for that. I also know that the rods and pistons are questionable at that power level, aren't they?

Can I boost it the way is, or will I have to build an entirely new combo anyway?

Could I get away with a set of heads and a cam and then boost it later, for the final push to 500, or is there just no chance in hell that the rods and pistons will stand up?
 
#17 · (Edited)
that calculator seems to be calculating CRANK HP. if you take a typical stock 345hp LS1 F-body trap speed (105-107mph) and calculate it with 3700lbs (3500lbs+200lbs driver) it comes out to 352hp for the 105mph trap.

according to my own guess, 97mph trap w/4050lbs is roughly 260rwhp or so. Obviously hes making more, maybe hes shifting at the wrong RPM and theres still a couple more MPH's in there without doing anything else. I think the a performer RPM (or air gap) + gears and a better carb will give him noticeable gains.
 
#10 ·
Applying a 20% driveline loss to the graph numbers (294 HP, 387 lb/ft) it works out to 367 HP and 484 lb/ft torque. That's spot-on for a mild build.

You'll pick up a little in your ET's, especially off the line, if you'll loosen up the converter a tad (a stocker just ain't gonna cut it, no matter what the year). MPH won't change much.

The 3.08 gears are hurting you, too. Swapping to 3.55 or even 3.73s would be a another tenth or two if you don't mind giving up a little roadability. Off the line performance would increase drastically, especially if you paired it with a looser converter (say something in the 1800-2000 range).

Brad
 
#14 ·
1FSTCAT,

Let me first say that you have a nicely built combo. Everything is well matched for the level that you're at.

I'm kind of puzzled when you say, "My dyno simulations all show this combo should make peak horsepower at 6000 RPM", when you got a custom cam from Scott. Scott would have told you a cam with those specs is going to hp peak around 4500-5000 rpm. It takes a lot more cam to peak at 6000 rpm. Your cam can rpm to 6000 rpm, but that doesn't mean it will peak there, as you have found out.

As far as you reaching 500 rwhp with your combo, the easy way, and cheapest, would to buy a 6-71 or 8-71 supercharger, a Blue Thunder blower intake, and 2 Holley supercharger carbs. The only thing you'll have to do to your existing set-up is double key the crankshaft and install a 3-inch exhaust system. The engine will idle even smoother, and you'll have god-awful torque everywhere. As long as you keep the engine redline under 6000 rpm, you'll be fine with the equiment you got.

Hope that helps,

Dave
 
#15 · (Edited)
I have two dyno jet dyno sheets of very similar combos the difference being that I ported the heads.

Your numbers correspond very closely with the numbers i experience on as regular basis with that type of combo. Your flywheel hp is in the 400 hp neighborhood as installed in the vehicle. My typical numbers for that combo are in the 305 to 315 range with a 9" rear end and C-6 with a mild stall convertor.

Your HP peak is not at all out of line either.

If you are looking for better numbers you need:

More static c/r. If you are not at 0 deck your static c/r is easily under 9 to 1.
RPM intake
Large valve better flowing heads.

Randy's statement regarding the variables on a chassis dyno are in my experience absolutely correct. Hell low tire pressure can cost a bunch of power by itself as can strapping the vehicle too tightly down on the roller.

Do you have the light yellow secondary spring in the vacuum secondary dashpot? Your secondarys may not be opening all of the way. I often see this with vac sec carbs...



:D
 
#16 ·
Hey, thanks everyone for your opinions, I really do appreciate it! I'm really glad to hear that the run looks correct for this combo. I posted here a few years ago, a dyno graph where the car was peaking at 225 RWHP and fell like a rock after 3200 RPM. That ended up being an issue with the timing set having been installed off one tooth at the crank. We finally got that sorted out last year and this as where we've made it.

After fighting for years to get it running right, I'm very glad to finally be at a point where I can drive it as I please and beat up on it on a regular basis!

Thanks everyone for your help! As soon as I can get my dyno videos edited and posted up on the net, I'll post them here for everyone to check out!

--Ed
 
#18 ·
I agree that his one restriction may be the intake manifold. I was turning 14.87 @ 93 mph in a 1971 LTD STOCK 429 except electronic ignition and a 204 214 .484 .510 cam with 200K+ miles. The car also had a holley list number carburetor for 1971 429 only(600 cfm 4160). His engine is almost the same as my build except I have 10.6:1 and he is running a much larger cam than I am planning to run. I know that my car will turn better than 14.50's by far after I finish my engine, so what gives? Seeing his numbers I may shift my plan slightly and opt for an RPM instead of the standard Edelbrock that I was planning to run.
 
#26 · (Edited)
well according to trap speeds alone it seems hes making about 25-30hp more than you. But i think his traps are a little lower than they should be given the power hes making and im willing to bet theres a couple more MPH in there by messing with the shift points. Which would put him at a solid 45-50hp or so more than yours. His ET's will improve with more practice and a better launch as well. These are just my 2cents.
 
#19 ·
I'm not sure what you are hoping for but those seem like very accurate numbers to me for your combination. My race motor has a .735 lift cam with a LOT more duration and it peaks at 6250 RPM. I think that the 4500 RPM peak of your motor is dead on. No way that cam will peak at 6000 RPM. Off hand I'd say they were good numbers for what you have.
 
#21 ·
im not sure if he was hoping for it to PEAK @ 6000rpm, from what i gather, he thought he might be able to make usable power up to that rpm. But it seems now he's bumped his rpm goal by 500rpm. Still to make usable power till 5500rpm im guessing he wants to know how he can bump the rpms up and maybe peak closer to 5000rpm and drop off after that.
 
#23 ·
Its a well matched build and the numbers all look right to me also.

If you are looking to get some more out of it without breaking the bank I'd up the rear gears to 3.55 or 3.73, bolt in a slightly looser converter (2400rpm stall), and consider dual 3" exhaust. I would bet you'd see a solid 1/2 second decrease in ET and the car would feel like a rocket to you comparatively. It do this before power adder. It will need it then even more.

Given the car model and the mild, fresh build on the 460, seems to me you have a perfect canadate for a centrifugal supercharger or an 80mm turbo (consider this if you are doing more exhaust work anyhow in upgrading to 3"). Keeping the boost under the hood adds to the sleeper apeal. You could safely run 8 to 10 psi blow thru (you'd need a different carb of course, and bigger fuel system) and drastically close up on the 500rwhp number you are after. I'd think it would dip into the 12's with that kind of boost in a full weight crown vic mild 460 adding the mods I listed above also. Impressive and definately sneaky.
 
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