Dyno time versus Engine stand
 

If a rebuilt engine is set up on a stand is there much difference than being run on a dyno?
can you do all the same tuning on the stand?
Dyno time around here is very expensive but run on an engine stand is much cheaper

You cant place the motor under load on a generic stand.

You can set timing, check for leaks, lash valves hot and break in a cam. But, you can't load the engine for tuning purposes. If this is a stock engine with the original stock tune then I would do the engine run stand.

I might get flamed for this, but if you have AFR's and plan on tuning on the boat I would skip the dyno if you run it on a stand prior. You might not know exactly where your peak torque and HP might be, but with the knowledge on this board they can get you pretty close.

this article makes the dyno process pretty intimidating for a non engine guy like me

http://www.hotrod.com/techarticles/g...g/viewall.html

502 re-manufactured built by a marina that runs a BBC re-manufacture program over the winter.. bored .30 over new pistons mild can (dont know the numbers) apparentl massaged heads. No idea about valve train, stock exhaust. I had the holley 850 built buy a really great carb guy but I'm torn about what to do before installing it.
Frankly I bought it to satisfy my itch to upgrade the old 330 454 and chose this one because the marina was able to validate that they built it and it was still on the crate that they shipped it on. It was never installed. If I had any sense back then I would l have likely made a different decision . The dilemma now is do I spend 1000 bucks to dyno it only to find that it doesn't run right or has the wrong parts (see article above) or do I run it on a stand and stick it in the boat. There is nothing worse than being involved in a past time and being clueless. You guys have no idea how lucky you are to understand this ****.

My only argument is how much fuel are you going to burn "dialing it in" in the boat if your baseline is way off? In my boat I could easily burn 5-600 worth chasing it and then you get to make adjustments out on the water. Real fun swapping air bleeds while the boat is rocking. I say dyno it and once it's in the boat all you have to do is enjoy it.
Edit: assuming it is mild and tuned conservatively on the dyno. May need a few tweaks once in the boat to get the absolute most out of it if you choose to be that picky.

I wish I lived near a couple of the guys on this board like Mild Thunder or Mike Tkach! when I walk in to the dyno shop they will see me coming lol

The $500 for a dyno session is worth every penny. 3 hours on the water + gas running back and forth or 30 minutes at a dyno. Plus you get to find all the leaks instead of a murder scene the first time you take it out.
When someone asks how many ponies (every stop) you have an answer instead of a guessing game.

I had a friend that always built his own motors and tuned them himself. after a couple of years I convinced him to go to a buddy of mine to put the engine on his dyno. when they started it made around 450 hp. when they were done tuning it made almost 520 hp. he figured out real quick how cheap the $500 dyno session was.

I just had mine dyno tune. It took from 8am till 440 pm with a 20 min brake for coffee. Best 500 i spent on the entire motor. I would of never got it dialed in. Oh and it made WAY more then exspected. Also helps with prop tuning since you know where your juice is. I didnt want to spend the 500 bucks after spending 12k building it but once again well worth it.

1000 around here

Where are you located? Maybe someone on here could shed some light on a shop that dynos that you weren't aware of. 500$ is the going rate here also. Especially an engine that is relatively mild (no huffer, ect)

Might be worth asking around. And yes I agree with what's said above, the money spent will be well worth it. You'll know exactly what you have and that it runs as it should.

Be careful what you wish for.
You'd then want superchargers, intercoolers, and bigger drives too. :D

Run it on a stand to make sure timing is all set, no water/fuel/ oil leaks...then if you are uncomfortable with your tuning abilit and/or want to save money by zeroing in on prop choice needed...bring it to a dyno.

Nothing worse and more expensive then putting a motor on a dyno that has some sort of problem like leaks or etc that requires time or tear down.

Where are you located ? Maybe someone knows of a good dyno shop that will help tune and not charge you a ton.

Edit in: Be forewarned, some dyno shops will get you a power # that's not correct and won't help you tune...which turns into a big waste of money.

Located near toronto

Oh. I'm out. I don't even know if $1k Canadian is a lot or not. LOL.

if by rebuilt you mean a refresh like bore job with same compression pistons,same cam,valve job ,rings&bearings,timing set than a run stand will probibally do the job but if compression ratio,cam or heads,induction system were changed a dyno is a good tool to help sorting the tune.just my humble opinion.

New pistons bore 30 over new cam new bearings nw valves and springs

LMAO 1000 canadian is like 1150 usd

So how much more power is made at an AFR of 12.8 on a dyno compared to an AFR of 12.8 in a boat if same exhaust/setup is used?
Just curious

i would think the same.we know the dyno measures the power but we have no real way to measure the power in the boat except mph vs a known past setup.

Mike when you finish a dyno session and you have the motor dialed in, do you assume there will be some additionaly tuning once its in the boat?
If so is it carb, timing or both?

looks like I have found a skilled and trustworthy guy that will tune my motor on the dyno, it wont be cheap but it will be cheaper than pulling it out afterwards if its not running right. US friggin rookies think its so simple to buy a motor and drop it in, we are pretty clueless.
Years ago I had 2 supercharged 454's built by Tommy from Chief, it was so straightforward that we did nothing, he handed the boat over running perfectly

I guess I should have searched "dyno" first lol

http://www.offshoreonly.com/forums/g...dyno-test.html

Around here you will not touch dyno time for $500.00. Also most of the shops around here build stock car, sprint car etc. motors..... They don't and wont dyno big CI blower motors on the little dynos they have. So the couple of shops equipped to do bigger marine supercharged, or for that matter big torque at low RPM motors, charge per hour thats its on the dyno set up & tear down is on the clock too. so you looking at a minimum of $1000.00.

usually the tune will be a little richer in the boat depending on the application but being a little on the rich side wont burn an engine down.

i know a guy that will spin anything on his dyno..close to me to boot..

Pay attention to the type of fuel they will run during the dyno session. For example, there is a local guy who is just around the corner from where I work with a dyno, so it would be super convenient for me, but unfortunately he will only run racing fuel on his dyno. He is concerned that the ethanol in pump gas will cause problems with his system. That won't work for me, so I am going to have to go somewhere else.

Probably also a good idea to ask up front exactly how they run the engine on the dyno. Do they break it in on the dyno in a controlled manner and make sure everything is good to go before they start flogging it?

That's another reason that it is a great idea to do both - start it up and run it on a cart, and then dial it in on the dyno, as SB suggested. That's my plan, and I'm building a startup cart just for this purpose. The cart will come in handy down the road for any future builds, and also to help your buddies out with their builds.

Dyno time is priceless! It is crazy what different cam, head, intake and carb combinations like and don't like. It produces real numbers for your exact set-up. Timing, spacers, header tube sizes, jets, fuel pressures, a good dyno shop will have a bunch of "variables" to try. And it generally is an all day affair! You can see where you're HP/torque is, where it falls off, which can help in things like propping the boat. If you know it falls off at 5500, you can prop up to 5500 instead of going down in pitch to just to get to 5800 because motor App on your computer told you 5800 was magic.

We always bust them off on a stand, first to make sure they run (so we don't get embarrassed at the Dyno shop--I have had one lock up wrist pins on the stand---but that's a long story) Break in the cam etc. That way you don't waste dyno time on that stuff.

Now having said all that, you can "tune" a motor in a boat, making runs, reading spark plugs, and I've done plenty of that as well. But for total comprehension of what you've built and what it does, dyno all the way!

Where we dyno we were told that the dyno operator no longer has any control over the correction factor.. don`t know if its the new software or hardware they had

Stimleck- bring it across the boarder to the buffalo area, 1 1/2 hours from Toronto. There are many dyno's in the area. One is $80 per hour and he's fairly quick (4hours or less) and the other is jan-cen and they range from $350-500. They are a big machine shop building motors upwards of 4,000 hp and have a very nice Dyno. There are lots of good engine guys over here and I have yet to pay 500 for a single Dyno run. It's worth the trip and every penny. Btw, isn't double r reasonable? They are in your back yard

If an engine that is properly tuned on a dyno nets only a .05 pounds of fuel better on the BSFC, that is three gallons per hour you will save on a boat using 275hp to cruise. That is a $500 fuel savings on 40 hrs of use.

I have seen poorly tuned engines run with a BSFC of .58 before tuning and be in the .44 range after. That's a 25% increase in economy. If you know what the load is, you can calculate fuel usage doing cruise simulations on the dyno. I've nailed it within a gallon per hour on houseboat engines.

We dyno every engine we build....or we don't build it. It's not worth the risk not to. We are going to start a exchange program soon, through a local marina (We are not a retail shop). A large selling point for us will be that every engine is dyno tested, with the customers carb and ignition when possible, and cruise load tested.

You do what you wish. But you asked and others have answered. I wish you luck either way. My guy ran a brake in program. I also started with 14.5 AF_R. Ran great but that is not good. Took alot of work to get it down to 12.6. My carb is a 950 QF off a 540 stroker. I only built a 509 mild 9.6-1 comp motor. My motor was run on 89 none on the dyno. Dyno program was set to only pull once conditions were set to where its going to run for real life apps. Best of luck.

thanks Double R wanted $1000 plus fuel

wow that is huge!
Thanks for all the advice you guys are awesome!