turbogrill Posted June 16, 2017 Report Share Posted June 16, 2017 (edited) Hi, I am in the process of refreshing my engine (bearings, rings). There is lot of suggestions on different break-in methods. The recommendations is not to push it until 500 miles, how do you do that on a race car? Let it idle in your driveway during the weekend? Edited June 16, 2017 by turbogrill This is the breakin for the engine Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted June 16, 2017 Technical Advisory Committee Report Share Posted June 16, 2017 (edited) 11 minutes ago, turbogrill said: Hi, I am in the process of refreshing my engine (bearings, rings). There is lot of suggestions on different break-in methods. The recommendations is not to push it until 500 miles, how do you do that on a race car? Let it idle in your driveway during the weekend? Can you post the clearances? If you built it loose, I would just run break in oil and short shift a few 15 minute stints and then change the oil and begin thrashing it. Edited June 16, 2017 by red0 1 Quote Link to comment Share on other sites More sharing options...
turbogrill Posted June 16, 2017 Author Report Share Posted June 16, 2017 Hmm...I don't know. I am just doing what the machine shop is telling me. The machine shop is supposed to have a "race engine" builder, but that can mean everything. Who knows, maybe the "domestic truck engine" builder built my Japanese samurai masterpiece. Is building it loose having a lot of clearance or the opposite? Quote Link to comment Share on other sites More sharing options...
Hi_Im_Will Posted June 16, 2017 Report Share Posted June 16, 2017 What @red0 said. Or, if you don't want to spend half a track day breaking in your motor, half an hour of slowly climbing up and down the rev range in your driveway will do it. FWIW, when I bought my new car with 7 miles on it a few weeks ago, I made it all of 5 miles before I started stinging it out and going WOT out of every corner. I think the oil got up to temp first... Quote Link to comment Share on other sites More sharing options...
turbogrill Posted June 16, 2017 Author Report Share Posted June 16, 2017 2 minutes ago, Hi_Im_Will said: What @red0 said. Or, if you don't want to spend half a track day breaking in your motor, half an hour of slowly climbing up and down the rev range in your driveway will do it. FWIW, when I bought my new car with 7 miles on it a few weeks ago, I made it all of 5 miles before I started stinging it out and going WOT out of every corner. I think the oil got up to temp first... Haha.. I will drive around the block a few times and make the neighbors happy. Nothing makes more friends then revving a chumpcar with a glaspack muffler. At least the kids thinks you are cool. Quote Link to comment Share on other sites More sharing options...
Evilwheel Posted June 16, 2017 Report Share Posted June 16, 2017 Drive it like you stole it, repeat as necessary. It's all subjective anyway, we drive ours about a hour on the street before we change the oil and thrash it afterwards. Works so far. Funny, the car rental we got at the Glen only had 3 miles on it when we got it, broke that SOB in for them right !!! 5 Quote Link to comment Share on other sites More sharing options...
mender Posted June 16, 2017 Report Share Posted June 16, 2017 (edited) 27 minutes ago, turbogrill said: Hmm...I don't know. I am just doing what the machine shop is telling me. The machine shop is supposed to have a "race engine" builder, but that can mean everything. Who knows, maybe the "domestic truck engine" builder built my Japanese samurai masterpiece. Is building it loose having a lot of clearance or the opposite? Talk to the "race engine" builder and find out what he recommends; if it's still 500 miles, I'd question the "race" part. Ask him about the ring end gaps as well; if he can't quote you the numbers from memory he may not have even checked them. End gaps that are too small will get you into trouble quicker than just about any other spec. If you're lucky, all you do is break the top ring and lose sealing. Next level is a broken piston land with chunks of aluminum bashing around in the chamber, and worst case is a split cylinder wall and the attending nastiness that can ensue. On the engine dyno we do a cam break-in if needed, about a dozen part throttle pulls working up to full throttle, then start the power runs while working the rpm up. By the time the engine has a couple dozen hard pulls the numbers are usually repeatable, meaning that break-in is mostly done. A race engine has to run hard from the get-go so is assembled with that in mind. Loose usually means the bearing clearances are on the high side; not needed these days, just causes a loss of hot oil pressure. Edited June 16, 2017 by mender 1 Quote Link to comment Share on other sites More sharing options...
Ron_e Posted June 16, 2017 Report Share Posted June 16, 2017 Break-in = run it till it "Breaks", then bring it "In". 6 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted June 16, 2017 Technical Advisory Committee Report Share Posted June 16, 2017 23 minutes ago, mender said: Loose usually means the bearing clearances are on the high side; not needed these days, just causes a loss of hot oil pressure. For Honda Main bearings the tight side of the spec is .0007" and the loose side is .0016". Where would you set them? Quote Link to comment Share on other sites More sharing options...
mhr650 Posted June 16, 2017 Report Share Posted June 16, 2017 Some people really believe in break in. A couple of years ago we got to VIR for the 24hr on Friday night around 10PM, there was a team driving their car around the access roads, went to bed woke up the next morning and the same car was still running around. I don't know when they started but they probably spent as much in gas before the race as some teams would spend for a 7hr race… Quote Link to comment Share on other sites More sharing options...
mender Posted June 17, 2017 Report Share Posted June 17, 2017 4 hours ago, red0 said: For Honda Main bearings the tight side of the spec is .0007" and the loose side is .0016". Where would you set them? Lots of things to consider; this is a good summary: http://www.enginelabs.com/engine-tech/engine/clearing-the-air-on-bearing-clearances/ 4 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted June 17, 2017 Technical Advisory Committee Report Share Posted June 17, 2017 19 minutes ago, mender said: Lots of things to consider; this is a good summary: http://www.enginelabs.com/engine-tech/engine/clearing-the-air-on-bearing-clearances/ Thanks for the interesting read. 1 Quote Link to comment Share on other sites More sharing options...
pintodave Posted June 17, 2017 Report Share Posted June 17, 2017 43 minutes ago, mender said: Lots of things to consider; this is a good summary: http://www.enginelabs.com/engine-tech/engine/clearing-the-air-on-bearing-clearances/ Cool, I'll stick to the .003/.003 (ok, a couple of tenths tighter) clearance to allow for my stock 'Murican junk flexing & moving around with my 15/40 oil that last 3 hp is for someone else LOL. Great article and cool to see Lake Speed JR involved in some good behind-the-scenes stuff. 1 Quote Link to comment Share on other sites More sharing options...
Justin9 Posted June 17, 2017 Report Share Posted June 17, 2017 the PO of my LT1 engine handled all the break-in period for my machine... and all the others too... Quote Link to comment Share on other sites More sharing options...
mender Posted June 17, 2017 Report Share Posted June 17, 2017 Murican junk gets 0.0022" for rods and 0.0027" for mains at my shop. 3 Quote Link to comment Share on other sites More sharing options...
pintodave Posted June 17, 2017 Report Share Posted June 17, 2017 14 minutes ago, mender said: Murican junk gets 0.0022" for rods and 0.0027" for mains at my shop. .0025 and .0027 sounds correct IIRC on mine from my buddy... whats a few tenths between friends Quote Link to comment Share on other sites More sharing options...
Bandit Posted June 17, 2017 Report Share Posted June 17, 2017 Tenths? Quote Link to comment Share on other sites More sharing options...
pintodave Posted June 17, 2017 Report Share Posted June 17, 2017 2 minutes ago, Bandit said: Tenths? Machinist talk man - tenths of a thousandth And I ain't talkin' pup tenths or circus tenths. 5 Quote Link to comment Share on other sites More sharing options...
Ogren-Engineering Posted June 21, 2017 Report Share Posted June 21, 2017 The fastest engines are broken in at race RPM to get the rings in the right travel. Any less and the rings hit the end of the path and bounce/scuff . Heat the engine/oil, rev to the right RPM under light load, repeat for about 20 min keeping the engine @ race temps. Race temps are crucial as the stuff changes shape/size and you want all of the goodies happy. Breaking in at less than race temp or RPM results in poor ring sealing. Post breakin change to a good synthetic oil and race. Quote Link to comment Share on other sites More sharing options...
55mini Posted June 21, 2017 Report Share Posted June 21, 2017 When we build a fresh motor with racing clearance we head to the dyno for tuning and the motor is run for about ten minutes on the dyno with lighter load and varying RPm's to get everything warm. Shut it off to check all fitting and for leaks and if all good it goes back on and we do several pulls with load and fine tuning. All done with fresh oil and filter and when done we head home to the shop and change oil and filter and are ready to go racing. First couple pulls are with lighter load and not to full red line but that moves quickly to full pulls with load and to red line. Quote Link to comment Share on other sites More sharing options...
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