Motor- Should I DYNO or NO DYNO?
 

Ok guy's, what does everyone think? Is it worth the extra bucks to have everything sorted out and just "plug" it in? I would love to save the money because I could do it myself. But, there's just something about seeing your baby on a Dyno and what it honestly makes in HP. Plus, having the pro's tune it for the best results couldn't be bad. Another thing, do you consider having a Dyno sheet a plus when purchasing a car (resale)? I know there's a lot of pluses but the money could go to some other areas. Let me know and thanks for the help, Matt

Yep, dyno it. I've dyno'd every engine I've built...for myself or for someone else. The last engine I built for myself, the dyno caught something that would have been a pain in the butt to sort out/fix with the engine in the car.

Plus you have a dyno sheet to show what it made. To me, when someone says, I have a 500hp engine, it doesn't really mean much unless they can back it up with proof.

Around here, it's $400 for a full day (8-10 hours) of dyno runs. It's well worth it.

What Blykins said!!!!!!!!!!!!!!!!!!!!!!!
I will not put my own motors in a car without having them dynoed first......It's a pain in the butt to go thru the trouble of installing it and finding a small oil leak or water leak that requires pulling the motor back out to fix......
Also, a dyno tune on your motor is well worth the money, to me at least..... found on my motor that a timing change of 2 degrees either way off 32 degrees resulted in a 8 to 10hp loss!!!!!!!!! I was more worried about getting the air/fuel mixture right and not melting pistons.....once installed, I have peace of mind knowing all should be well.......
Around here, dyno time goes for about the same 400 bucks for an 8 hour day and so far, I've been lucky and have never spent more than about 5 hours from start to finish at the dyno shop..........

David

I would only dyno the motor on a chassis dyno.

Engine dyno are good for breaking in the motor. Any adjustments you make on the engine dyno will need to be changed once you install it in the car.

I perfer to use rear wheel hp for power calculation.

I think you should save the money and dyno it on a chassis dyno. You will get more for your money.

My .02

Known build or experimental?
 

If it's a known build, then the engine dyno is just a good way to spend money. If it's an unknown build, then you will probably save a bunch of money by hammering out all the experimental qualities of the build in an environment where you have ready access to everything that can go wrong. If any of the seals, freeze plugs, gaskets, heads, cam, etc are in question then by all means break it in on an engine dyno so you can easily remedy those issues and move on. If it's a known build using known parts and just like 100 that have been built before, then I don't see the benefit. I would just break it in on a motor stand. If the motor stand has a brake on the output shaft for applying some load, even better. If not, then don't sweat it, you can apply load as soon as it goes in the car. Just test it for leaks, break the cam in, then install it in the car.

B

No dyno time for my motor, but I MIGHT put it on a chassis dyno at some point. Like Byron said, mine is a 'known build' utilizing mostly standard components. I all ready KNOW I gave up 100 to a 150 horse when I 'detuned' it on the last engine build. It's working well for me, I'll spend my money on other things.

Byronrace & Excalibur are right on the money, so save yours. A 351W built by an experienced pro who has done the same build before will come out within 2% of the numbers that the builder says they will dyno out at -- unless there's a big problem. And if that's the case, the builder will spot it when he breaks it in on the stand. Put it on a chassis dyno and tune it up after you've driven a thousand miles or so on it.

Thanks for the replies! I guess for me it will come down to knowing the engine is a legit "400HP" or the comfort level of the engine is ready to go. My fears are that I get the engine back and I don't get it running right away and then I find problems 4 to 6 months down the road. If there are problems it's still is in the "engine builders" hands to resolve. Plus this could be a better way for the engine builder to stand by his work. I could screw it up too far and he wouldn't warranty it after I messed around with it. This is a huge part of the build and I'm as nervous as I can be! I wish I could just call up Roush or KC but I don't have that luxury. Mine is a common build that is basically a Edelbrock "power package", nothing fancy. I didn't want a car that wouldn't idle in traffic or that needed adjusting every time out. I have seen too many Cobra's that are, well, just not street able. My old racing boss said do it and don't question the money it is well worth it. Thanks again guy's! Matt.

Well, then post the results here so we can all eyeball them -- and make a note on the page as to whether he's running straight tubes or some mufflers on the engine when he makes the runs.

I just read an interesting article at Autoblog.com( In the Autoblog Garage: 2008 Ford Shelby GT500 Mustang - Autoblog ) comparing the Mustang Bullit to the Mustang GT500. Some interesting insights. The GT500 is quite a bit heavier (3900 lbs) than the Bullit and has about 185 more horse (4.6 Bullit vs 5.4 blown V8). In the 1/4 mile it's just about a second faster, BUT on the 'street' the difference is NOT substantial. The GT500 is traction limited, something Cobra owners know about all to well. If you can't hook up, your wasting your time and your money. Extra power translates into a higher trap speed and lower ET IF you run a measured 1/4. Hole shot or stop light to stop light? No difference to speak of.

Small block 302's would almost always get the 'hole shot' on me at the strip. That would give them 'hope' just before I blew their doors off. :LOL:

I was astonished when I rebuilt my motor and gave up an estimated 150 horse. You can MEASURE the difference in accelleration and trap speed at the race track, but on the street? I can barely tell the difference at all! Before: 11.90 with open headers, after 11.99 WITH the side pipes on! I never got a chance to run open pipes at the strip with the new motor before they closed it down. I bet I would have been right back in the low 11.9X range.

MPG doubled, streetability vastly improved, I'm a happy camper. :D Was 667 flywheel horse on the dyno. Now, I GUESS around 500 horse, which seems to be just about optimum for a set of Goodyear Bill Board tires, which still spin. Slicks would no doubt make a big difference.

Who needs a dyno? :D

I had just had my motor dynoed it was an unknown built . I really just wanted to break it in and sort out any leaks etc etc. This way I did not have to take it out for some silly reason . Well for the money I thought I was saving by picking up this motor I had to spend it again to straighten it out . It was an expensive lesson learned . So for all the reasons stated above I think it is money well very spent to have it put on an engine dyno.When I get the dyno sheets in my hands I will post the results of them.

Chris

One other good point is that if you really want to know how much power the engine makes, you won't find out on a chassis dyno due to all the unknowns of exhaust/driveline parasitics. Chassis dyno numbers aren't as fun to brag about either....that 400hp engine will probably only put down 300-320 to the tires.

unless you are really proficiant at building engines............have it at least broke in on a stand or cell. then once installed and bugs if any sorted. now to the chassis dyno we go. but thats just my opinion.