engine dyno mating

[juanbenae]

just finishing up the last touches of a 3.0L spec motor rebuild that i will be looking to get dyno tuned & broken in very soon. quick run down of what ive done- an early, big port with 90k on it when this project started that i took all the way down to the crank with a polish n all the plugs pulled and races cleared. machined the rods locally, had gamroth's magic head work, along with a set of his forged CP euro pistons, & honed my original niki's. gt3 rod n crank bearings, everything in the chain boxes is new, cams & rockers checked out sound, oil pump was good, cleaned and reinstalled. new rocker shaft hardware, wrightwood kits top n bottom. will reinstall the weber 40's i ran previous as ive run the fuch out of money, so no 46's in '13...


so, regarding the engine dyno what do i need to know/do to prepare? i have a couple local bay area options im considering for the dyno tune & break in. i do not know the particulars of the specific machines either shop has at this point. i realize my questions may just lead to questions from you before you can dispense any advise, so please work with me. any general info that might make discussions with the particular shops im considering more constructive would be appreciated.


as i understand it most engine dyno's will take the output from the clutch disc. or is there others that may mate to the flywheel? id assume they prefer to wear your clutch disk more than anything that attaches to the flywheel... the shops im looking into are both porsche specific, so could there be an opportunity for linkage to the crank? seems doubtful as the slippage of a disk or flywheel should be a good thing.



ignition? will i need to have all the entire ignition present so just 12v is needed at the starter? i imagine the 14 pin connector might still be utilized, and i will need to determine the 4 prong connectors for the tach, coil, & such. what should i know here?


oil? i assume the return line that runs under the bell housing is in play to be sure. but does the on engine oil cooler play a role? im very confused here, so should you have the time,, do elaborate. i have assumed a case of break in oil is mandatory, but what about a filter? is there a corking fee if i bring my own...


AFM monitoring? ive got a single 02 bung on one of my heaterboxless ssi headers and run single burns scrubble packed cans. should a second 02 bung be considered on the other header to monitor/tune each bank independent?


ive done a few searches and have read thru many a dyno threads here in the ERF and have found nothing thats suited my questions above. if yir aware of one, or other resources, please, do link here for my consumption.

why no yard work has been done in weeks....--




tia,

toby

[chris_seven]

Most dynos I have used connect with coupling that has a flex plate bolted to the flywheel. The hexl palete allows some parallel and angular misalignment between the driving and driven machines.

You don't really need a clutch as the dyno can be set to zero load at idle.

The type of brake used isn't very important as it only provides the load. The torque measurment system. however. should have a decent resolution and accuracy as should speed measurment.

What will you do about the lube system? I would want to fit my own tank and cooler if you think this is needed.

Clearly you will want to monitor engine temperature and the heat exchangers wont have any air flow unless you have a fan.

Break In Oil, I would use Joe Gibs BR or XP4 they have the same basic formula and are high Zinc.

I also wouldn't let the engine idle at below 3000 rpm for the first 15-20 minutes..

I think fitting a second 02 bung is a good idea.

[304065]

congrats on getting this far

it is common to use a gutted pressure plate to connect to the dyno- this bolts to the flywheel and then the dyno connects to it. If you ask the shop and you don't get a straight, clear answer as to how the power flows then this is an answer itself-- a real pro will have done this many, many times

do you have the capability to start the engine and break it in and get the carbs and basic timing set before going to the dyno? this will save you big money. I would be very surprised if the jetting of the 40s works with the new configuration-- so as Chris says above, working backwards from what you are trying to find out, which is AFR across the power band, a pair of 02 sensor bungs in the exhaust are a great idea

if you can get it started, then getting the idle mixture, correlation and side-to-side balance set up should take an hour or so-- again, you don't want to let it idle, follow all normal break-in procedures about varying the rpm so the rings seat. Also set and check the timing curve and err on the conservative side, you will be sneaking up on maximum timing on the dyno, but you don't want to be there on your first pull

I'm sure you get this but it bears repeating that when you finally get ready to do your first pull, all the details should be sorted out-- the dyno stand should come with its own oil tank and +12V, you supply the ignition system you want to use, exhaust, everything else, just like it's ready to go into the car.

this way when the first pulls happen you can be confident that you won't see an aluminum hailstorm and can focus on what the dyno instrument is really good at-- getting the fuel curve and ignition curve set and making pulls to determine best power

if there is any equipment you want to experiment with to see if it makes more power, have it ready to go on the engine right down to nuts and bolts-- I would even go to the extent of bolting it up beforehand, then removing it so you know you have all the right fasteners, tools, everything you need

at the dyno time is money and you want to have the maximum time to iterate alternatives, that is the fun part

see my thread called "the final exam" for some photos of a well set up dyno cell

and have fun!

[PFM]

Toby,

Ok so I had a long reply and the machine ate it. First off the most important thing in my book is does the dyno shop dyno Porsche engines? If not they could learn on your motor if you are OK with that, I would not be.

So to your more specific questions, connection to the dyno can be via a clutch disk or a flywheel coupler. It depends on the dyno. Clutch slip is NOT a good thing on the dyno it makes readings go off. If a clutch is used it will always be engaged so no linkage is needed. The dyno will have its own starter so no worries about starters.

Ignition, bring what you run (the whole thing), using a dyno ignition tells you nothing about your ignition. Yes it is best to have it configured for a 12 volt run wire, the dyno will source that to your ignition. As for the 14 pin and or alternator no need for them on a carbed engine. The dyno has a tach.

While on ignition timing is a BIG deal on these motors, approach timing slowly start low and work your way up. The other way around is a problem. I suggest you start well lower than what you think is good. Bring your timing light so you know what IT reads on your motor. Always use your timing light after that we have seen 6 or more degrees difference between lights. FYI a timing error of 2 degrees can kill 20 FT / LB of TQ AND hurt the motor. Timing needs to be set on the fuel you will run period.

Oil system, this is tough as the lines you run on the car may not fit the dyno. You may be better off with the dyno provided gear. An external cooler is recomended, yours or the dyno's I strongly suggest a cleanable filter so you can do a health check early on in the break-in. Oil is your problem and should not call for a corking fee. No synthetic for break-in. A shop that does Porsche motors will likely have all the adapters and lines you will need.

Exhaust, If possible use your entire system less the O2 sensor(s) the dyno should have two or more. Put a bung in both banks, a float level or jet problem on a non monitored side could cost you.

So to bring, a motor that should start, all static checks done. The fuel you plan to run, oil yes lots, a cooler if you are using one. Spark plugs are good to have too, a bad one costs time.

I hope this helps,

Stay Tuned,

PFM

PS If you want a SoCal dyno shop PM me I can help.

[KTL]

PM Mike Bruns @ JB Racing here on the forums (MBruns) and he can give some of his experiences on this thread? He'd be able to share the specifics he expects to see on the engine in order to make it a smooth dyno hookup and run process.

Gert’s Engine Rebuild & Upgrade (Chasing 300Hp, yes another one sorry)


Start viewing at post #38 because you got no business drooling over the goods that went into that toit 3.0L in that thread......

[juanbenae]

very good info. i appreciate the time you've taken to share the knowledge. i will look to meet with a couple of bay area porsche exclusive shops for discussions to determine where ill drop the new & improved plant to be taken to task.

in the mean time, can anyone show me the best spot to place the 02 bung on the passenger side SSI header collector? ive got the driver's side to compare, but that seems to be in conflict with the oil return line. see here, the drivers side can be seen on the collector. same spot for the passenger?





tia

[KTL]

T,

Yeah i'd put the passenger side bung in the same place, just a bit closer to 12 o'clock on the pipe to avoid the S-hose Typically you want the bung to be as close to the collector as possible. At least that's what the instructions typically say on any O2 installation (air-fuel ratio gauges) i've done.

[juanbenae]

well thats done... have felt like an expectant father, not sleeping well for the week while at jwe waiting on the run in & tune. it was good to see it come off the dyno in one piece with the power it made... great experience though. i hung out while as it was tuned by jerry & rich and we worked out a couple bugs. like i had way too hot of plugs...

[KTL]

Hottest plug for carbs is typically NGK 5 and that's for a street car. I've run 7 or 8 for the past few years. What plug was you running?

Here's a handy plug heat range conversion chart

[Walt Fricke]

Kevin - great chart (no doubt you didn't create it, but no matter). I lost my ability to cross reference NGK and Bosch when Bosch changed its numbering system many years ago.

[KTL]

Yeah I just stole it today from sparkplugs . com It's current as of Oct 2012

[juanbenae]

i had ngk 7's in it and i was moved to a bosch 4's

[KTL]

This thread is useless w/out dyno sheet.........

[PFM]

Toby,

So you moved the plugs 1 heat range cooler and picked up 4 HP? Or what? BTW I get not posting the Dyno sheet but would be good to see what the plug change did for you.

[PFM]

Toby,

Glad you had a good Dyno experience.

[KTL]

I got the initial impression the heat range was way off. One notch on the heat range doesn't seem that bad to me. My understanding with carbs on an engine used for racing is that you try to use as cold a plug as possible to just avoid fouling. That can sometimes be pesky because if you don't get the engine up to temp & running at higher rpms quickly, fouling can happen quite easily? Like if you let it hang around idle too much.

[juanbenae]

Originally Posted by KTL

This thread is useless w/out dyno sheet.........

now i have it in pdf and can't post it... if someone can switch the format pm me an email address.

PFM, thanks for the knowledge. the plug change was done prior to the observed dyno numbers. a clogged jet caused some investigation that the plugs were pulled. when the hot plugs were found they suggested cooler due to the required pump, 91 octane spec class rules the hotter plugs present a greater opportunity to promote detonation.

t

[PFM]

Tobi,
Put on your screen and print screen it, save as an image, post as a photo. For my 2 cents worth the Dyno is a better tool than an opinion, not to say a plug change is not important it is but let the Dyno decide if it makes more or less power. Very glad you got to a Dyno and had good success.

[KTL]

T,

I have Adobe Pro here at work and can convert it to a jpg, if the screen capture that PFM suggested doesn't work well.

[KTL]

Here's T's dyno info. Nice flat torque curve, good HP, fairly steady (very steady for carbs) AFR/lambda values. Nice job dude. You builds a good motor!!!