911 engine test stand

[JakobM]

boosted79

an engine stand is NOT used for break in. I can not see how that is so difficult to understand....or why you would think so.

an engine stand is used only for e.g. "walk-around" oil leak test etc. To do a break in you still need start, warm-up and check things are right before adding real load.

Your time on google / air-plane quote says the same: "A new, rebuilt or overhauled engine should receive the same start, warm-up and preflight checks as any other engine." Hereafter you do the break in

I dont use an engine stand, I use the cars as engine stand on still sitting dynos for prep before break in, and I don't believe the engine cares much whether I check for oil leaks and warm up inside or outside a car before tuning on the dyno.

Lets just agree that we don't agree how to prep before tuning/break in, or how glazing occurs and move on

[boyt911sc]

Originally Posted by JakobM

boosted79

an engine stand is NOT used for break in. I can not see how that is so difficult to understand....or why you would think so.

an engine stand is used only for e.g. "walk-around" oil leak test etc. To do a break in you still need start, warm-up and check things are right before adding real load.

Your time on google / air-plane quote says the same: "A new, rebuilt or overhauled engine should receive the same start, warm-up and preflight checks as any other engine." Hereafter you do the break in

I dont use an engine stand, I use the cars as engine stand on still sitting dynos for prep before break in, and I don't believe the engine cares much whether I check for oil leaks and warm up inside or outside a car before tuning on the dyno.

Lets just agree that we don't agree how to prep before tuning/break in, or how glazing occurs and move on

I use an engine test stand to get the motor ready for start up. You can not do a break-in process if the engine is not running well. So the first objective is to get the engine in a condition that you could rev and run the motor. The OP was asking for a very simple question about a diagram that he could use as reference. Someone jumped in and started all the confusion. Hope people would take time to read the post before getting involve in a given thread.

Tony

[Tippy]

Originally Posted by chris_seven

If you drove it you did apply load, maybe not much but significantly more than when idling.

Yeah, yeah. Ran it for about 20 minutes, then a cool down. After that, drove it lightly for 500 miles.

[Tippy]

Originally Posted by boosted79

Tippy - how do you know you wouldn't have had better leak down and compression by loading it during break-in?

I don't. I was always told to baby an engine after rebuild. Did it to the 5 engines I've rebuilt.

Totally understand the theory of loading and will do now Dr. Chris explained this.

But, I'll never forget the life lesson. Dad rebuilt an engine for my brother. Right after rebuild, dad takes it on the road, and hammers it. It locked up and drug the tires like 10ft not even a few seconds of revving to high RPM. Left an impression on me when I was younger than 10 years old. HAHA

I believed you must baby them new.....

[chris_seven]

I don't really subscribe to 'hammering' new engines and do remember the earlier period when we had to 'break in' brand new Fords and the like.

The advice used to be don't exceed around 3500rpm for the first 500 miles (Not V8s but UK 4 cylinder engines that revved normally to 6000rpm) and then gradually increase revs.

The advice was to drive normally and avoid allowing the engine to labour.

This was at a time when standard cylinder finish was made using a 220 grit stone whereas today we have much finer plateau honed finishes making the job much easier.

I would just drive a modern engine normally and bring up the revs carefully and drive whatever speed seems comfortable for the motor.

My last rally engine we broke in for 50 miles around the IOM TT Circuit the night before the event. The car won its class over the next 3 days and 2 years later it is still running well.

[boosted79]

"The OP was asking for a very simple question about a diagram that he could use as reference. Someone jumped in and started all the confusion. Hope people would take time to read the post before getting involve in a given thread."

????

Please read the OP's first post in this thread. Here is part of it:

"My goal is to run in my newly rebuilt 3.0 while refining jetting and tune on headers and muffler choices etc."

He wanted to use the stand to "run in" his new engine and play with jetting, headers, mufflers, etc. He was told that was a recipe for failure and would lead to an engine with low compression and a lot of blow by due to unseated rings because of no way to load the engine. Info from two major companies that know something about the subject was posted that supports that.

Are we not supposed to comment on actions that a poster wants to take that are clearly detrimental?

[Tippy]

Originally Posted by chris_seven

I don't really subscribe to 'hammering' new engines and do remember the earlier period when we had to 'break in' brand new Fords and the like.

The advice used to be don't exceed around 3500rpm for the first 500 miles (Not V8s but UK 4 cylinder engines that revved normally to 6000rpm) and then gradually increase revs.

The advice was to drive normally and avoid allowing the engine to labour.

This was at a time when standard cylinder finish was made using a 220 grit stone whereas today we have much finer plateau honed finishes making the job much easier.

I would just drive a modern engine normally and bring up the revs carefully and drive whatever speed seems comfortable for the motor.

My last rally engine we broke in for 50 miles around the IOM TT Circuit the night before the event. The car won its class over the next 3 days and 2 years later it is still running well.

Many big builders here support flogging the motor shortly after it fires to seat the rings.

That there is no problem running the engine on a track right after rebuild.

Changed my whole perspective on break-in......or lack of.

[boosted79]

"Alright. So bolt it in, start it up, and check for oil loss. Then drive (LOAD) it at reasonable rpm's under 3.5 maybe but do this for how many miles?

The 3.0 SC Weber 20/21 webcam regrind data from WC says do not allow the engine to idle below 2k for the first 15 minutes of use.... That would be easy if the carbs were tuned prior to break in... conundrum 101 ....???"

Someone on here should be able to give you jetting for your engine configuration to get you running.

Don't forget to check your timing, I have a light set up and ready to go before I fire it up. I start it and hold at 2000 while watching oil pressure and temp. I have someone watch for any major leaks. If none then I run it for 10 to warm it up. Then I shut it down and have someone else get in, start it and hold at 2000 while I check timing and do a once over on the engine. If ok then I take it for a ride, not letting r's below 2k. I get it in 2nd and give it close to WOT, shift to 3 at 4500 and WOT again up to 4500, hit 4 and same thing then close throttle decel down to 2nd again and do it all over for 15-20 times. Obviously you have to have a back road to be able to do this. I'm not sure the local law will give you a break for running in a new engine. Then I drive it fairly normal but don't redline it but bring rev's up to redline over a couple hundred miles. Don't baby it and don't maintain a constant engine rpm for a prolonged period, ie. don't get on the interstate and set it at 70 for an hour. Once you have done the initial break in city driving is a good way to treat the engine the first few hundred.

That's my method.

[Rawknees'Turbo]

Originally Posted by Tippy

Many big builders here support flogging the motor shortly after it fires to seat the rings.

That there is no problem running the engine on a track right after rebuild.

Changed my whole perspective on break-in......or lack of.

As I know you recall me mentioning in the past, I learned this ^^^ procedure from a top level engine builder in the motorcycle roadracing circles (pro and club level), and let me tell you, I was pissing myself when the Ducati 748R engine that I had spent a couple of months building, in preparation for a CMRA Endurance season, was being run right to the rev limiter (11,600 RPM) on a chassis dyno before it had even been ridden two feet (this was after three heat cycles at a stand still - throttle blipping, etc - and a low rpm pass through the gears on the dyno in order to make sure I had done the gearset correctly, too.). I was in the dyno booth, standing to the side of the bike, saying "holy shart" over and over in my head! After the dyno, the bike's first operation was WFO on the track . . .

His explanation as to "why" made perfect sense to me and mirrors what other builders have to say on the subject, and the engine did not blow up the entire season and made great powaaaa', too!

When I overhauled my Turbo engine, I rang that bisch out immediately, too (not on a dyno, though) . . .

[Bob Kontak]

Originally Posted by Rawknees'Turbo

I rang that bisch out immediately, too

Pin head. Talky-talk poofta.

[Tippy]

Originally Posted by Rawknees'Turbo

As I know you recall me mentioning in the past, I learned this ^^^ procedure from a top level engine builder in the motorcycle roadracing circles (pro and club level), and let me tell you, I was pissing myself when the Ducati 748R engine that I had spent a couple of months building, in preparation for a CMRA Endurance season, was being run right to the rev limiter (11,600 RPM) on a chassis dyno before it had even been ridden two feet (this was after three heat cycles at a stand still - throttle blipping, etc - and a low rpm pass through the gears on the dyno in order to make sure I had done the gearset correctly, too.). I was in the dyno booth, standing to the side of the bike, saying "holy shart" over and over in my head! After the dyno, the bike's first operation was WFO on the track . . .

His explanation as to "why" made perfect sense to me and mirrors what other builders have to say on the subject, and the engine did not blow up the entire season and made great powaaaa', too!

When I overhauled my Turbo engine, I rang that bisch out immediately, too (not on a dyno, though) . . .

Yep, I 'member that.

[Rawknees'Turbo]

Another vote of confidence for the flog-it, break in procedure; Bobasaurous Kontak does that at each engine overhaul in his van (frequent re-builds due to so much machine use! ), and it hasn't failed him yet!!!

[crashtest22]

I am by no means a pro at anything engine. But.....
I am all for the break it in hard camp.
I have always done this with motors I have built (Not Pcar) and always had great results.
Last race motor I had built was for a vintage jag and I we took the motor to a very well known Tuner in the bay area (Hasselgren). I went with the builder for this. The engine was setup on the dyno then run at varying rpms for 15 ish min and was done.
I remember asking was that it and he said "Yup".

Then we did a pull. looked at all the numbers including the AFR and adjust the carbs a bit and went again. We pulled several times and changed jetting several times till we were happy with the AFR and power numbers then called it a night.

this was a Jag XK120 with new crank to head.
I remember watching this video a while ago https://youtu.be/bvfz5s11NOc
and if you watch the end of the video you can see the dyno setup and run. He runs at idle for a min which I am sure was after the initial check to make sure no leaks and such then goes full wood and with the brake on the dyno lets it come up slow to redline then back down. I would assume they did this a few times.

[boosted79]

I like to at least let the engine warm up some before I flog it just to get some heat into the cylinders to stabilize piston/cylinder clearance. But that is left over from my two stroke days when you could get a cold seize because the piston expanded faster then the jug and seized if you didn't get it warm before giving it the juice. I would think that may also be good practice for these air cooled wonders?

[boosted79]

That is an interesting video.

No sparing of the 574 that's for sure. Including on the thru-bolt o-rings at 2:50?? It doesn't look to me like they put it on the webs at 1:42? What is he doing @ 6:02, oiling the valve stems? Why do they start it with high injectors then switch to low injectors for the run in?

[crashtest22]

lol I noticed the same thing on the 574 lots of it and everywhere. no curl T or threebond anywhere. just 574.
I had seen another video where dude used 574 on all the orings as a "Lube" and extra insurance from leaks

I am 90% sure he has it on the webs. at least looks like it to me.

I guess why not use it on the thrubolt rings? right?

at the 6.02 mark he is CC'ing the combustion chamber to get compression ratio.

and I am not sure on the injector stuff.

[boosted79]

OK, that is a good way of doing it! Minimizes chance of calc. errors as when cc'ing the head on the bench to determine CR. Will only work if the plug hole is in a spot in the chamber so you can fill the whole chamber completely with the head on the engine.

[donporfi]

Forrestkhaag
It seems nobody answered your original request for a diagram or information regarding how to build a test stand.
There is acompany that used to sell test stands for air cooled engines , now I think they only sell an adapter ring to use the engine starter in a test stand.
Check this site
Engine Test Stand for Air-cooled Porsche and VW

They used to sell a test stand like this with the adapter ring.

[donporfi]

This is what we use for the initial start up of rebuilt 4 cylinder air cooled engines.

[florio]

To further on the OP, here is my take on transforming a dumped laboratory bench as an engine stand. I turned it upside down and welded on attachments to the legs to hold the engine fixtures, oil tank, gas filter, etc. It is solid, but was designed to work with the transmission bolted to the engine (to provide the mountings for the starter motor). As such, without the transmission there is a cross-bar to hold up the front of the engine. Four castor wheels complete the set. I'm not planning on using it to break in the engine, but just to test it to make sure it works before mounting back in the car since I have no idea if the engine runs or not.



The bolts are long because that is what I use to raise/lower the engine onto a dolly!





Good luck!

Dario