Interesting conversation.

Tom, I just had my new motor dyno tuned by a local guy who uses a Mustang, and he was saying it's a better tool for tuning because of the load factor. He also said there's about a 15% difference on the average between his dyno and a DynoJet unit, so if I wanted broadcast numbers use the other machine down the street........is that sounding about right? His point was dynos are really only useful in comparing gains from mods. I thought it was pretty cool of him to be so candid about the relative strengths and weaknesses between the two machines!

 

HEH,

I didn't mean to stir up a hornets nest, but my dyno operator, said literally the same thing as caboboy was saying...

Again I'm not bumbed by the numbers, I only use them as baseline for tuning... I only dynoed as a request from a customer I was doing some independent testing for...

The mustang dyno operator also mentioned that it was much easier to "hold" the car at a specific RPM on the Mustang dyno rather than a Dynojet. I'm not baggin on either one... I think they both can serve their purpose.

I compared my dyno runs ( I logged with my Autotap at the same time we dynoed) and I agree with TJ it did "faithfully" seem to reproduce my road tests... He also ran the 1/4 script on my car as well, the 1/4mile run was much slower, when he romped on it the tires were spinning on the rollers and raining rubber on the pavement.

 

after reading this thread, I bet my mildly modded 86 with a crane cam, headman headers, ansa dual exhaust, and a hyperchip, probably gets 120 hp

Talk about a thread that kills the hope of modded HP gains.

 

The Mustang or for that matter any load bearing dyno is the tool to be used for tuning. A dyno without a eddy current or a water brake abosber is only useful for doing a WOT power curver. Without the power absorbing capability there is no way to hold a engine to a specific cell for tuning. Just today I tuned a ZR1 and a 84 C4 with a later model 383 TPI conversion. Without its power absorbing capability there would be no way for me to tune the VE maps. This particular car used a 90/91 7730 ECM which uses a speed density strategy. Without the ability to load the engine at part throttle speeds there would have been no way for me to tune the VE maps. I could have used the SWAG method of tuning and got close. But at $150/hr for dyno tuning time, I doubt my customer would have accepted "close".....

I would think 15 to 20% is about the normal spread between the Dyno Jet and the Mustangs. I have found that number to be very close in differences between the two. A local Dyno Jet shop has much higher than that. But another DynoJet shop that also dyno'd the ZR1 I was working on today was very close to what my measurements were. On my dyne that ZR1 put down between 445 and 455. It was very consistent between passes. I think today we may have made 8 or 9 passes on the dyno today. LocoBob can attest to those numbers.

The C4 had to make 4 passes to finalize the chip. I also ran it in road sim for about 20 miles to iterate the VE table mapping. I started with a baseline of 265hp and finalized with a 335Hp pass. He has some other issues such as a possible CAT going away and a small OD Y pipe in the rear section. I think there is more to this engine if some additional port work is done on the intake base.

Your local guy is absolutely correct in saying that the dyno is a tool that can gauge differences between mods. The real test is what the car is going to do on the road or the track. One thing to do if you are serious about making power. And that is to stick with one dyno shop and hopefully one dyno operator. Going from shop to shop isn't the thing to do. You won't know if the gain or the loss was from the difference in the dyno setup, his correction or his means of correction factor, or how the guy straps your car down, or if the second shop has his dyne located so that your engine is sucking in its own exhaust. Sometimes this happends if the shop arrangement is such that ventilation isn't optimum. All these factors and more can affect the bottom line. So find a shop you are comfy with and stick with them. For the most part the people that have come to me have left with smiles, maybe not always because their numbers were great, but because I always made them feel welcome and treated them like friends with the same interest.

 

Nahh.....a 86 Malibu Station Wagon with a 305 put down 145 on my dyne so I am sure you would have that one beat Oh that same wagon went 16.75 at the strip, on my dyno it went 16.90 in a quater mile simulation test. It would have maybe done better but my apprentice went to sleep at the wheel when I said "GO!"

 

I just thought it was funny when the the GM mechanic I bought my car from was like "oh yeah, its over 300 hp after I put the headers on, the cam, the chip..blah blah blah..." all I could think is...yeah....RRRRIIIIGGHHHHTTT. I guess some people dont understand the non-linearity of HP gains when doing mods. I dont understand all of it, but I at least recognize it. The guy was trying to sell me the car on the basis of the mods he did, of which, i really didnt care about anyways, but it made him feel better.



snoopdan

 

FYI to all

I contacted Mustang Dyno directly and talked to a technician. He said that the average drivetrain loss on the Mustang 500 AWD for a manual is 26%-28% and an automatic is 28%-30%

I realize that this might be a large lead-time, but my car club is organizing a dyno day on Sat., May 7 in Waukesha, WI. The cost is $40/car for 2 runs. The shop is offering further discounts for your car at a later time also. If anyone is interested drop me a line as I need to schedule the number of cars.

 

This is exactly the point....

You also have to make sure the atmospheric conditions are the same or for the dyno to be in a climate controlled facility in order for the readings to be accurate, correction factors aside.

The only "true dyno" for real world HP is the drag strip... I've said it time and again for the "dyno dreamers"... you don't drive a dyno, you drive a car! It's truly funny to go to a grudge night at the drags and hear the chatter in the lanes about "I got 400hp on the dyno..why am I not running faster?".

If you want to know your rides actual rwhp on any given day (have to take the weather into account), go buy a Moroso Power Speed Calculator (about 10 bucks) and plug in your 1/4 mile MPH (NOT ET). You'll have an accurate "no B.S." read of your actual HP.

MPH is indicative of horsepower. ET is indicative of traction. Too many people confuse ET for HP.

 

To the original poster...

What you have there sir are the results of a poor combination. That dyno graph follows the same basic curve as any other TPI, it's the nature of the intake. The cam very likely wants to make power above the powerband that the intake will allow. As with any gain of upper end power, it will come at a sacrifice of low end torque. What the guy did basically was throw in a cam that would make upper end power but the intake can't support it and it sacrificed some of the lower end power that the intake can support.

Just looking at the A/F ratio the tune might not be THAT bad. Sure it's lean below 3500 but that's easily fixed in the computer. That'll give you higher torque numbers but there isn't gonna be a lot that can be done above that point as the A/F actually looks pretty decent. Flattening that A/F curve would be simple with a few pulls and would probably make the car feel a lot better off the line. It would give you more area under the curve but ultimately your peak numbers still wouldn't be all that great.

I just breezed this thread, were the complete cam specs ever posted? I think I remember seeing lift but what about lobe seperation and duration? With the cam specs I'm sure we could help you figure out an intake that would make it scream. It might be a great candidate for a super ram, maybe just some large tube runners for the TPI. It really just depends on exactly how aggressive the cam is.

I wouldn't get down so much on the actual numbers, they're not important. The graph says it was a dynojet, so assuming it's in good working order these numbers can be "reasonably" compared with other dynojet numbers. Remember though that your auto trans is going to soak up a lot of power on the dyno. This doesn't mean that the car isn't fast, just that it's not set up for racing the dyno. What is more important is that this is a fair place to start as YOUR baseline. Pay attention to the shape of the power curve and see what you want to do with it, ignore the numbers for the time being, just look at the shape.

 

I understand your point, I think what gets lost is that people think the dyno is the end all be all. The point I have always made about the dyno is that it is a good tuning TOOL. It allows you to see how much change and the nature of the change to your power curve that a particular modification gives you. This is valuable information, but it is just information.

Example, my car makes 382 HP on the dyno and 356 lbs ft of torque. That's all well and good, it should be hella fast, but it only runs the 1/4 at 12.732. There are people who make less power and run it faster. Here's the kicker though, I run that 1/4 at 116 MPH! The MPH is there, my issue is with traction and the driver!

There are ways to make a low HP car run fast at the drag strip and there are ways to make a high HP car go slow. I know I'm not consistent enough to milk my car for everything it's worth at the track, so I've used the dyno to judge my performance gains. Low and behold though, as you've said for every HP gain I've had on the dyno I get a corresponding MPH gain at the track, even if my E.T. didn't improve at all.

The track isn't the "ultimate" either because some cars make crazy power but just aren't set up for drag racing. There is too much of a human factor involved. That's why I prefer to use both. I get my mods done and my tuning sorted out on the dyno, THEN I go pound the car to death at the track.

 

with above.

mustang dyno - tuning
dyno jet - for good numbers

i think those numbers are pretty close for a stock motor.
185/.8 = 231HP
260/.8 = 325 TQ

take it to the track for real numbers.

on a side note, my mustang dyno numbers last year gave me 239HP and 332 TQ at the rear wheels (282HP, 390TQ). mods: no cat, stock exhaust manifold, ported plenum, free mods, hypertech chip.

i haven't done anything more to the car since then, i'd like to throw it on a dynojet to see what the difference is.

 

One recurring theme that I've seen with Mustang dyno's is that they're just damn inconsistent from one to the next. One guy will make numbers right in line with a dynojet while another will make numbers way lower and there doesn't seem to be any rhyme or reason to it.

This leads me to believe that there might be more in the operator than there is on the dyno. A dynojet is simple, you strap the car down, you press a button and you go. Assuming the dyno is in good repair and the computer running it is compensating for atmospheric conditions correctly they are actually VERY repeatable from day to day and dynoject to dynojet.

I don't know enough about the Mustang dyno to compare, but from the sounds of it there are LOTS of variables on how the tests can be performed. Thus from one operator to the other you will very likely get completely different results. This is fine for tuning purposes because what you're looking for is the net change, the numbers don't matter so much. It just makes it very hard to compare numbers between different Mustang dyno's with different operators.

I know dynojets, I've worked with several and from my experience they are actually very consistent, making it easier to compare numbers from one to another. Mustang dyno's just have more options and thus more variation. They are probably the better tool, but unless the test used is standardized it can't really be used to compare one car to another.

 

Exactly my point, Nathan... According to your MPH (116), you should theoretically run mid-11's, but as stated in my previous post (and you already stated it too), ET is a function of traction, not HP. And the weather has a lot to do with HP output, after all...an engine is really only an air pump. Air quality has a direct effect on HP. This is why I say the track is the best place to find the HP on any given day, car setup notwithstanding. Obviously, if you're spinning the tires all the way downtrack, the MPH can be affected, thus making a "real" HP reading bogus. However, most street cars don't kill the tires in that manner.

Bottom line: Dynos are a useful tool, but as stated before NOT the "end all be all". The same can apply to track tuning, but the results are more "real world".

 

Thnks for the info...here is a copy of the actual spec sheet from the cam:

 

That looks like it turns into a 210/216 .440/.454 114

Interestingly enough you look on Crane's web page and this is what you find

GREAT FOR 305 HO, PERFORMANCE 350 TRUCKS AND TPI-EQUIPPED 350 ENGINES. GOOD MID AND TOP END TORQUE AND HP. AXLE RATIOS OF 3.73 OR NUMERICALLY HIGHER REQUIRED. AUTO OR 5- SPEED MANUAL. MUST USE ADJ. FUEL PRESSURE REGULATOR. (50 STATE LEGAL IN 81-87 267-400, CARB EQUIPPED CARS ONLY. C.A.R.B. E.O. D-225-25) BASIC RPM 2000-5000

 

If this were true, then that '85 Malibu wagon with the 305 should have been turning in the 10's.......

Seriously, I've been told something very similar; ET is a function of gearing and MPH is a function of power. They used the following analogy: take your car to the strip, make a normal run or two, then make a run starting out in second gear; your ET will drop dramatically but your trap speed will be nearly identical... (I've never tried it)

Larry
code5coupe

 

Um. No thanks! That'd put me 1/2 way through overdrive gear.

Now, if you can make good power up to 5000 rpms, be my guest. But those notes are meaningless when you're talking about different heads throughout those years.

 

one thing i don't like about the mustang dyno( or at least teh one I was on) is the lack of a spark plug wire tach lead. It uses a math formula to calibrate RPM. That doesn't work so well with a 5600 flash converter when the motor will only turn 7200 RPM

 

Yeah....I have a 3.07 ratio in the car, so I guess I am SOL on that too. But since I inherited the cam and it was installed in '98, it may have been an OK option back then. Not to defend the former owner's choice, but the car runs good for general driving and passes CA smog, doesnt overheat, idles smooth, starts up first crank, and I drive it everywhere.

If there is a low cost way to improve the engine preformance with the existing cam . I think the dyno idea came from the original 310 HP claim...and one of my firiends who just had his C5 redone to 600 HP (suposedly 450 at the wheels)...After a run last weekend, it got my curiosity going on exactly what I had, and how I could make it better.


Thanks for all the great posts and input

 

yes, like someone said before its lean below 3200rpm.
a good tune up followed by a custom chip (purhaps the dyno shop can do it?) will get you a good 20-30 ftlb's of torque in that range (maybe more).
RJ