Going to the dyno!

[Hissing Cobra]

Yep, I'm headed to the dyno next Saturday (Feb. 26th.) I can't wait! Now I'll get to see what kind of horsepower I have at the wheels (I'm guessing 320.) I hope to be able to tune the two carburetors in search of some more power. I know that this dual quad setup is killing me on total horsepower, but I just love the look. ;)

Since I've never been to a dyno before, what should I be on the lookout for? Is there any questions that I should ask? Educate me!

[85stang]

I have never been but I hope you have fun.
What carbs are you running, 390s or what?

[Hissing Cobra]

Thanks. ;) Two Edelbrock 500's. I have two calibration kits and they'll be sticking the wideband exhaust gas measuring tool into the exhaust pipes. Hopefully we'll find some horsepower.

[sleepercoupe]

who is going to be driving it? are they going to let you? might want to adjust the rev limiter (if you have one) down a couple hundred rpm's just to be safe if your not going to be the one driving it.

[anthonydalrymple]

An adjustable timing light & distributor wrench does come to mind as something to bring along.

[Hissing Cobra]

I don't really know who's going to drive it. If it's us, I'll probably let my brother drive it. We have the 6,600 rpm chip in the MSD box. I hope we don't hurt it! We'll also be bringing the calibration kits, cordless drill (with bit for carbs), the aforementioned timing light and the wrench for the distributor bolt. Is there anything else that I'll need?

Anthony, It's cool to see your car is now down into the 12.30's @ 111! I'm in your neighborhood with my times. I hope that I can find some more horsepower to be down that low too. ;)

[anthonydalrymple]

Anthony, It's cool to see your car is now down into the 12.30's @ 111! I'm in your neighborhood with my times. I hope that I can find some more horsepower to be down that low too. ;)

Thanks! It's now slower; believe it or not. Reason? I've decided to be 100% California smog compliant & pass the smog\sniffer test with ease. i figure I just lost 15 horses! I'm installing an electric fan & a few other tricks that are up my sleeve to get the times into the 11's by the end of summer while staying smog compliant...... Anyone smell the laughing gas?;)

[JEEPMAN1]

I don't really know who's going to drive it. If it's us, I'll probably let my brother drive it. We have the 6,600 rpm chip in the MSD box. I hope we don't hurt it! We'll also be bringing the calibration kits, cordless drill (with bit for carbs), the aforementioned timing light and the wrench for the distributor bolt. Is there anything else that I'll need?

Anthony, It's cool to see your car is now down into the 12.30's @ 111! I'm in your neighborhood with my times. I hope that I can find some more horsepower to be down that low too. ;)
I have been to the dyno alot,I have never seen them let the customer drive it.Big reason being insurance issues.I would take timing light, jet kit,plug sockets.and a broom in case it gets fun and you have to clean up rods on the floor!!
I would hope for more than 320 with those big carbs!! I put 328 rwhp at 6600 with heads flowing 202 intake and 160 exh. cfm with a custom cam and a 650.I love the dyno!! Sounds great take a video camera.

[Mike Croke]

The place I go, the owner makes the call about the driver. I run my car since the guy trusts I won't do anything stupid. :oops:

Essentially, your car will get strapped down onto the rollers. There was an experiment locally playing with tire pressure and how tight the straps were to see how the higher rolling resistance affected the power measurement. Turned out to be a 20-30hp variance on a car making about 375 at the wheels.

If you drive, do as instructed to the letter. Typically, the operator will instruct the driver to bring the wheels up to a decent road speed in 4th (or 1:1) gear and hold a constant speed. When ready, the operator will begin the test and the driver floors the accelerator. When the driver reaches the max rpm being tested to, push in the clutch, lift off the throttle, and select neutral. Do not touch the brakes! The dyno has it's own internal brake which is a lot stronger than the car's brakes. If the driver tries to brake, the roller will try to shoot the car off. This is a bad thing. Makes the dyno operator very unhappy.

Have fun and take pics/video.

[Hissing Cobra]

Cool! I didn't realize that there was so much involved. I probably would feel safer with them doing it. The place that I'm going to is called "Mike Dez Racing." He's got a great reputation as the place to go in the Mass/Rhode Island/Connecticut region.

It's interesting between the differences in the horsepower just from the air pressure and the tightness of the straps. I never would have thought about that.

As for my estimate of 320 at the wheels, I'm basing that from one of those online horsepower conversion calculators. I hope that it was conservative!

My dual quad intake is only good to 6,500, but I do have a 1-inch spacer underneath each carb. When I went to the track, I had the 6,800 rpm chip in it and it was making power up to that point. Do the one inch spacers give you more rpm? I've since taken the 6,800 chip out and installed the 6,600 chip. Should I reinstall the 6,800? We also have a 7,000. We'll bring that one with us, but I don't think that we'll be using it.

As the date nears, I'm getting more and more excited. I just hope that I'm not picking pieces up off of the floor! Oh yeah, the video camera will definitely be getting used.

[anthonydalrymple]

It would be a good idea to bring the bigger chip; you may decide after seeing the first dyno run gragh that the power is indeed continuing to climb. So, for the next run; you go to 6,800 & find out if the hp finally peaks. Have fun!;)

[Hooptie]

make damned sure its strapped down right...lol

I've seen three or four cars rock off the rollers in a pull, scary stuffs. And as such, I strap my car down now.

Its really not all that hard/weird. The owner/operator will odds are make the pull, there will probably be a wideband tuner used on the car, a computer moniter showing rpm, horsepower, torque, wheelspeed and more than likely the air/fuel mixture, they will pull to your desired rpm, basically shut the car down, let the in floor drum brake stop the wheels, then look at the charts.

Most places seem to do a three pull deal. One base pull and two test pulls with things like timing adjusted and fuel pressure reset.

Have fun, get at least sound clips, and scan the dynosheet.

[Capri50]

my friend has had a dynojet 248c for years now that I help setup. Since I do all their computer work, i'm able to mess with Autologic software, Accel Gen 7, F.A.S.T, PMS, etc. One of the coolest setups was a F.A.S.T setup on a road racing AC replica with a real 427 side oiler.

The peak #'s are fun, but I like to look more at the area under the curve. After seeing dozen's of different combo's go through, it's interesting to see how different the curves are based on their combo, cam choice, etc. Sometimes the peak #'s are up there, but the power is all over the place. I prefer to see long, flat torque curves. I acheived that goal with the 331 and a changover to the B41 blower cam. My current tune will blow the DR's off at 50mph if I bring up the boost. fun, but scary. time for new tires in the spring.

definately bring a camera. For glory or carnage, it's fun to have a reminder. If anyone has a video, they should post it. Mine is in the sig.

have a good time

[Zap's 85 GT]

The engines RPM capability is usually camshaft dependant. You can take the other pills for the MSD. You may or may not need them. THey'll fit in your pocket so it cant hurt to bring them.

The dyno operator can see an acceleration graph + Air-Fuel ratio in real time with a monitor right near the drivers door. After he sees power dropping off he will stop the run, or if he sees andy trouble like a misfiring engine or the air-fuel ratio going dangerously lean he will abort the run. Then he'll come down out of the car and the computer will spit out the H.P/Torque curve graph that you are used to seeing. Its much easier to just let the dyno operator run your car on the dyno. It'll save time and money since you're paying by the hour anyways.

[EFI 4-EYE]

Personally I always drive mine on the dyno. It's usually up to the customer at this place, and the guys who run it happen to be friends so it's not an issue. Good luck with the dynoing and get some video! I predict 310-330 hp, as I have a very similar setup with a slightly higher compression 306 with heads and all the goodies and I made 315 on a Dynojet

[JEEPMAN1]

Cool! I didn't realize that there was so much involved. I probably would feel safer with them doing it. The place that

My dual quad intake is only good to 6,500, but I do have a 1-inch spacer underneath each carb. When I went to the track, I had the 6,800 rpm chip in it and it was making power up to that point. Do the one inch spacers give you more rpm? I've since taken the 6,800 chip out and installed the 6,600 chip. Should I reinstall the 6,800? We also have a 7,000. We'll bring that one with us, but I don't think that we'll be using it.

Your cam determines you rpm range,what kind og duration you got at .50?what is the lca on the cam?

[Old_Timer]

my friend has had a dynojet 248c for years now that I help setup. Since I do all their computer work, i'm able to mess with Autologic software, Accel Gen 7, F.A.S.T, PMS, etc. One of the coolest setups was a F.A.S.T setup on a road racing AC replica with a real 427 side oiler.

The peak #'s are fun, but I like to look more at the area under the curve. After seeing dozen's of different combo's go through, it's interesting to see how different the curves are based on their combo, cam choice, etc. Sometimes the peak #'s are up there, but the power is all over the place. I prefer to see long, flat torque curves. I acheived that goal with the 331 and a changover to the B41 blower cam. My current tune will blow the DR's off at 50mph if I bring up the boost. fun, but scary. time for new tires in the spring.

definately bring a camera. For glory or carnage, it's fun to have a reminder. If anyone has a video, they should post it. Mine is in the sig.

have a good time

I did check out your sig area.
Your Capri is nice.

I gotta ask you this...Who did the transmission? That thing shift good! ;)

[Hissing Cobra]

Your cam determines you rpm range,what kind of duration you got at .50? what is the lca on the cam?

My cam is as follows:

Cam Lift = INT. .335, EXH. .350
VALVE LIFT= INT. .536, EXH. .560
LOBE CTRS.= INT. 103, EXH. 113
LASH HOT= INT. .024, EXH. .024
ADV. DUR= INT. 310, EXH. 320
.050 DURATION= INT. 248, EXH. 258

I hope that I gave you all the info that you wanted. I'm kind of new at reading cam cards. LOL! :lol:

The dyno that I'm going to be strapping this beast on is a DYNOJET. Is this a good dyno? Are the numbers that this unit produces as good as other dyno machines?

[Capri50]

The dyno that I'm going to be strapping this beast on is a DYNOJET. Is this a good dyno? Are the numbers that this unit produces as good as other dyno machines?

Many of the dyno's out there are Dynojet 248C's. The other type you see, but not as common is a 'Mustang' dyno (no relation to the car).

As long as your comparing your results to another Dynojet results, it's similar. The Mustang dyno puts different load on the rear wheels. It better simulates the weight of the car, and will turn in HP/TQ #'s lower than a dynojet given the same combination.

If possible, i'd prefer to tune a high HP turbo/blower car on a Mustang dyno where the A/F is critical. I have seen people leave a dynojet with 11:5-1 and toss a gasket at the track, because real world load of the car, + a little heat soak was enough to push the A/F into gasket popping territory.

With an N/A car at 11:1 or so compression, you have more flexibility with A/F, so that isn't really an issue.

[frdfandc]

Here is a vid of my last dyno run with the old combo. I'll post vids of the new combo when its competed.


http://ccr.jbeez.net/content/dynoday031304/darinfinalpull.mpg

[Hissing Cobra]

Cool video! How would I go about getting a video on the web? Also, does anyone know what the air/fuel ratio should be?

[Capri50]

Also, does anyone know what the air/fuel ratio should be?

for the A/F, you should be fine with ~12:5 -1. You could go as lean as 13:1, but you really want to leave yourself some headroom. As I posted earlier, the dynojet's do not load the car like a Mustang dyno would. Some experienced dynojet ops will recommend at least 1/2 point of A/F to compensate for full weight load, and heat soak at the track.

You want to tune for relatively safe power, not a lean kamikazee run.

It also depends on how much timing you plan on running, and what type of fuel you plan on dyno'ing with?

[Hissing Cobra]

Good discussion! I also agree with the safe tune. This car and engine cost me too much money to throw it all away. As for the timing, right now I believe that it's at 16 degrees initial with 36 degrees total (does this sound right?) I'm trying to remember what my brother told me last August, when he bumped it up at the track. I know that he's bringing his timing light and distributor wrench and he plans on playing with it. We'll be using 93 octane gas.

Last night, I was talking to my brother and he stated that sometimes you can tune a car to run perfect on the dyno, but it won't function correctly on the street. Is this true?

[Old_Timer]

Good discussion! I also agree with the safe tune. This car and engine cost me too much money to throw it all away. As for the timing, right now I believe that it's at 14 degrees initial with 36 degrees total (does this sound right?) I'm trying to remember what my brother told me last August, when he bumped it up at the track. I know that he's bringing his timing light and distributor wrench and he plans on playing with it. We'll be using 93 octane gas.

Safe tune is more important than Horsepower and torque numbers.

Too many people are bragging about dyno numbers but they keep forgetting the safe tune.
Most Dyno operators doesn't have a clue about BSFC, Volummetric Efficency and Air Fuel Ratio. They just aimed for highest horsepower to make customer happy.


Last night, I was talking to my brother and he stated that sometimes you can tune a car to run perfect on the dyno, but it won't function correctly on the street. Is this true?

Your brother is correct.
Nobody races on Dyno. :roll: Dyno is a tuning tool. Just get your engine in tune and do the final adjustment on track or street.

[Capri50]

I would start with how the car runs right now, to establish a baseline, check A/F, etc. Then based on the results, you can tweak various things timing, fuel pressure, etc. One change 1 thing at a time between pulls so you know what is making a different + or -

Your brothers comments are open for interpretation. :)

Like I mentioned earlier, some high power setups with blower/turbo/nitrous will tune for 11:5-1 on a dynojet, and wonder why they are blowing gaskets (or worse) at the track. The dynojet doesn't take into account the weight of the car (the actual load on the motor), and the heat that most experience with repeated laps at the track.

This is why the big boy racers will hunt down a Mustang Dyno, because it can at least simulate the weight of the vehicle during the pull for better tuning accuracy.

in the end though, you are running a somewhat mild setup with 11:1 and have plenty of headroom in the A/F area. Your not tuning on the ragged edge of detonation to find that last extra 10 HP as many unfortunately try.

My last dyno run on pump gas was at a steady 10:8:1 through the pull. Some will say that is too fat, but not for my tastes.

One of the best tuning methods is the now affordable Wideband O2 setups that do data logging. Dynojet sells one for ~$500. beware of the cheapie's you see all over the place. If they don't use a true wideband 02, they are junk. With the Wideband kit, you can cruise through the 1/4 mile, see the A/F the whole run, and tune accordingly.

http://www.widebandcommander.com/

it comes with everything needed, and the appropriate logging software. (cheapie laptop will suffice). It also taps off the ignition to record A/F vs. RPM range for playback.

[Hissing Cobra]

Thanks! It's good to talk with you guys about all this, as I want to educate myself as much as possible. Also, I'd like to avoid all pitfalls if possible. I'm renting it by the hour, so I'll baseline it first (documenting the metering rods, springs, and jets beforehand.) If I need two hours, so be it. My goal is to get it as close to perfect as possible, without it entering lean territory. Trying to eek out that extra horsepower isn't in it for me. I want the max that I can get and be safe.

I've got one quick question though. Because I have two carburetors (each with 500 cfm) I know that this is a lot of fuel going into the engine. Hypothetically speaking, can one carb have different springs, metering rods, and jets than the other one? Right now, they're both set up identicle. Also, we have the linkage set up so that the primary side of both carburetors are functional during cruising. This means that 4 barrels are open during the cruise mode and the other four open at WOT.

Believe it or not, this setup runs great on the street and at the track. We have experimented with the progressive linkage where two barrels are open on the front carburetor, while the rest kick in at WOT. This configuration didn't go over too well and there was a big hesitation (lean spot) during the crossover between the cruise mode and WOT. This is why we're running the setup that we have.

The car does run rich, but not to the point of any problems. There is no gas washing of the cylinders, fouling of the plugs, hard starting, etc...etc...etc... It actually drives like a regular car. Any thoughts?

[Zap's 85 GT]

I wouldnt start messing with different setups(springs) between the two carbs. It would be really hard to set it up to run good because I'd think it would make certain cyl's rich and certain ones leaner, making any sort of hesitation or rough running that much more difficult to narrow down.

Tuning for the dyno and tuning for the street are indeed two different things. You arent at WOT all the time on the street and jetting for max power will usually make the cruise miserable. UNLESS the dyno operator really knows what he's doing with carbs. What really makes a difference is getting the car to do a 70mph cruise on the dyno and reading the A/F ratio. Then jet the primaries accordingly. Thats how I did it on my Mach 1 and I asked the operator to do it that way specifically. After the primaries sre where you want them, then go on to tune the secondaries. I cant tell you how many times I've seen people jet up/down a carb by the primaries only because the secondaries use metering plates, then wondering why it runs like crap on the street. There are ways to tune metering plates but the Dyno operator needs to be up to snuff. Edelbrocks are a whole different ball of wax when it comes to the secondaries.

[ultimatebulk]

I know that dual-carb setup may look neat, but man-o-man what a nightmare!! A 650 would be completely adequate for your motor, jetted up. You could run a jetted down 750 no problem with those AFR 185 heads too ...

I'd love to see what your car would do with a Victor Jr intake and a 750. Stand back, here come 11.50s !!!

[Hissing Cobra]

Yeah, I know that the dual carb setup is a pain to tune and one can open up a can of worms as to how to tune them. The good news is that we have them pretty good right now. There's no driveability problems whatsoever and with the way we have them at the moment, it ran in the 12's.

I am toying with the idea of buying a Victor Jr. and a 750, but that would be my "track only" toy. I get a lot of positive comments on the dual carbs and they look great when I'm at the shows. They definitely set me apart from the other contestants.

This thread is good. ;) I'll be taking everyone's advice and tune for safety (12:5:1 air/fuel), calibrate the carbs to each other (like they are now) and hope for the best!

I'll keep you all posted on how we do. ;)

[Hissing Cobra]

Well, we just got back from the dyno. Not bad at all. I followed all of your advice and would definitely recommend that everyone do this when you're done building your cars.

I didn't make as much power as I wanted (my estimate of 320) but we did come close. I had to keep telling myself that peak power isn't everything. ;) We found that we had both carbs tuned right on the money. During the first pull, the car richened up on the top end of 4th gear (air/fuel was 11:5:1.) Total power at the wheels was 303 rwhp and 269 lbs. of torque. We took the carbs apart and went with one size smaller on the secondary jets. That allowed it to run at 12:5:1 and that's all we needed. A second pull resulted in 308.3 rwhp and 279.3 lbs. of torque. From there, we advanced the timing to 38 degreees (total) and it pinged. Power was still 307 rwhp and 279 lbs. of torque though. A fourth and final pull (timing @ 36 degrees) resulted in this graph.

http://www.mustangmods.com/data/13874/dyno_graph.jpg

[Zap's 85 GT]

Thats a nice flat torque curve. Wish My Mach 1's was that flat.

[anthonydalrymple]

Nice! i went to the dyno last night too..... :twisted: Got me a chip burned to help offset the horse\torque lost from reinstalling the cat's & being 100% smog legal.....

[moelll]

NIIIIICE

ill be lucky even with all the mods im planning to do if it makes around 225 hp

[Hissing Cobra]

Anthony, how did you make out at the dyno? I'm guessing that you're in that ballpark too. Thanks Moell ;) l!