Tristan Bull

I'm going to be buying a 10AE here pretty soon, and have a quick question. The car has a recently rebuilt engine in it, with approx. 300 miles on it as I understand it. I'll have to drive the car approx. 2000 miles. I didn't figure that would be terribly hard on the motor, since it would be highway driving and wouldn't be hard. However, the owner thought that driving it for such long periods of time wouldn't be good for it. I never really thought about that, and it does make sense to me. Now, I may be able to get ahold of a trailer to pull the car with, but that would cost a lot more money as far as fuel goes. The RX-7 is pretty thirsty, but the truck is even more. Also, driving the truck out there would be more expensive than say a bus ticket. So what I would like to know is whether driving the car 2,000 miles would be harmful to the motor or not?

Thanks for your help,

-Tristan

BlackR1

it'll be a great way to break in the engine! change the oil at 500 miles (200 more miles) and then change it again at 1500. It shouldnt be hard at all on the engine, if you dont have any cooling issues, and stay off the boost.

adamlewis

No! Long trips are not a good way to break in an engine!
You need to vary the load on it to break it in properly.


Now that Ive said that, Im not 100% exactly HOW bad it is...But Ive asked this question before ( and seen other people ask it ) and the answer Ive always seen is to NOT DO IT!

Icemark

yeah, for best break ins you want to vary the engine speed as much as possible, not sticking at one constant speed. A long trip is just the opposite of that. It is a long time at a consistant speed (probably 2500-3000 RPM).

Since the motor already is half way there with 300 miles on it, are you sure that there is not any site seeing you can do to add another couple hundred miles on in city traffic before you drive a long time on the highway? Ideally you should have at least 500-600 miles (and an oil change) before the trip.

Also remember since the motor is new avoid RPMs above 5K when test driving. Once everything is seated and running perfect, then you can use the whole rev band.

Mazda says for proper break in:

ilike2eatricers

I remember reading something about heat cycles and how it will help the engine break in.
I suppose this means that running it for long trips is not a good thing.
Please someone correct me if I am wrong

Tristan Bull

okay, so it looks like this is not a good idea. How about if I shifted between 4th and 5th gears on the highway some? Would that help?

So I supose I should look into getting the trailer then.

ilike2eatricers

Well I dont see how that would work in regards to heat cycles because in between heat cycles there must be allowed time to cool properly before starting the next cycle. Someone again please correct me if I am wrong.

88 SE

Assuming it's been rebuilt on used housings, i see now issues with a long trip. ON a used housing rebuild.. having the apex seals wear into the grooves should take priority.. constant speed or varying wont matter, as long as they get worn into place.

Engine speed wont be that hard to vary even ona long trip. Chances are at some point you will come across mountains of some sort wich WILL cause varying engine speed and temperature.

bingoboy

and traffic

hypntyz7

Well, Im going to throw in my 2 cents as a REBUILDER myself.

I feel that a long trip is the best way to break in an engine quickly. The word has been spread for a long time that road trips are bad for breakin, but NOBODY has ever been able to explain to me or anyone else why that is, other than "well, I guess, uh..." or "I think it is because...". No scientific explanations.

Sure, you want to vary load and rpm, which you do largely even on a road trip...aver all, there are curves, hills, variations in traffic, etc. All teh while you're going faster or slower, and accelerating/decelerating. The only reason I can think of that requires variation in rpms for breakin is so that both leading and trailing edges of apex seals get worn in...acceleration "tilts" the seal in it's groove one way a hair, and deceleration the other way, so you actually have 2 wear patterns on each seal). Road trips, in my mind, still satisfy this requirement. After all, even if you're on flat land with no traffic, you're not perfect, you're gonna adjust the throttle from time to time, meaning acceleration/deceleration.

Ihave broken in tens of rebuilds on long road trips varying from 100-800 miles, and nver had a problem. All engines wind up reaching full compression one way or another...the quality of the engine is directly proportional to the quality of rotorhousings used in it, more than any other single factor.

That said, you can do your breakin any way you want. I for one, would DEFINITELY, 100%, no 2 ways about it, be driving that car home. Not only would it save you considerable time and money in towing and equipment rental fees, but it'd allow you to finish breakin of the engine. When I get done building and installing an engine, I look for an excuse to head off to lexington, atlanta, charlotte, etc. to help with a quick breakin. Most people from out of state who have me do installs for them, after arriving home, report that the car is a hundred times stronger than when it left my driveway.

Maybe I can get rxse7en to chime in here. We did his rebuild in a few days and he drove it almost 600 miles straight back home (had a couple miles on the clock when he left). He reports that the engine is strong as hell, pulls hard, idles perfectly, etc. This with removed emissions and a streetport.

Tristan Bull

Awesome thanks for the reply, hypntyz7. Hearing that from an experienced rotary builder gives me confidence to drive the car home. I calculated how much it would cost to tow the car with a trailer, and figured up that it would cost roughly the same amount as it would to ship the car, so if I had to tow it I would just ship it and avoid the hassle. But anyway, I trust that you know your stuff as an experienced rebuilder, so I think I'll be driving the car home. I'll just have to make sure to buy oil and a filter or two along the way. I guess I'll be changing the oil in a rotary for the first time heh.

Thanks for everyone else's help as well.

rxse7en

Kev rebuilt the engine in two days, fired it up, let it sit for half an hour, we said our goodbyes and I left as it was getting dark. And beginning to rain. 600 frickin' miles home in the dark and rain through the mountains, down hills, next to tractor trailers, no guard rails...

Anyway, the engine was pulling 18" at idle within the first 1000 miles and now after putting over 3000 miles with varied driving it's pulling 20"+ at idle. That first 600 miles made it much easier though.

I believe if you can get those seals seated early on you'll be much happier. We rebuilt my engine as a precaution. One of those rare good compression turbo engines with NOTHING wrong. The housings being in good shape may be a factor in the speed in which your engine recovers. Good luck on your drive/rebuild/break-in.

Brian

Cory Simpson

Wait I'm confused how long is the break in period??? 600 or 2000 miles, I was under the impression that it is 2000 miles.

rxse7en

I had a 3000 mile break-in. Most have 2000+. My ride home was 600 miles from the moment after we started the engine for the first time after the rebuild.

Brian

JasonL

I also had my engine rebuilt a month ago. Then the engine builder(Scathcart on this forum) drove it to my house(600km away). Hardest thing is keeping it out of boost. I had a streetport and all emmsions removed too. I now have 3000+km on my engine and it pulls very strong. I'd say go for it too. Just keep your eye on your temp/oil pressure gauges, and check your fluids every fillup, also check for exterior engine leaks... Might want to plan on getting the oil changed ahead of time for each city etc...

Icemark

Perhaps your highway long drives are different than we have in California, where say if I was to drive from my home in Northern CA to San Diego (about 550 miles).

80% of the drive would be at a constant 75-85 MPH and 5th gear. This would lead to only the front edge of the apex seal wearing in and wearing in only at 2500-3200 RPM. No stop and go, no major hills where RPM or gearing is changing (other than driving through Lost Angles of course)

That would be a bad way to break in a motor.

Now if you had consistent gear and RPM changes, accell and decel on the engine and were able to use the entire rev band while driving, that would be a good break in.

But a long trip for me is driving 500 miles at 85 MPH and only stopping for gas.

Cory Simpson

I'm sure if you looked at a map, you could find a little windy road that goes around all of that, and threw a bunch of little towns. And that would force you to stop and go. But it would take you three times as long.

Roy James

So what are the concequinces of driving say the whole 2000 miles at a perfect 2500RPM (hypothetically) and you only wear one side of the apex seals. Then you go off and row through the gears thinking that your motor is broken in and then you let off the gas. what would happen when you let off? could it crack a seal since that side of the apex seal isnt broken in yet? If not, then **** it and drive on.

BDoty311

I thought the break-in period was 600 miles? Or is it different for TIIs? I drove the first 500 miles with only 1 primary injector and 2 secondary injectors, fixed it and put 600 miles on both of the rotors.

hypntyz7

Breakin period depends largely on the rotorhousings involved in the build. New rotorhousings can have less than 500 miles breakin required, and run very well to begin with. After all, it is a perfectly flat surface (housing) against a perfectly flat surface (apex). Very little has to be worn together here.

Used housings can vary in wear...some look very good, some look like ****, but any of them can be used in a rebuild provided they dont have blown apex damage. So, if you use a real good set of housings, well breakin might take 1000 miles or so. For a really poor but useable set, say 2000.

You can feel when the engine is basically broken in...the first startup, the thing doesnt idle really smoothly, has a bit of a hard time pulling out from a stop, doesnt have all it's throttle response, is a little hard to start, etc. As breakin occurs, compression rises and these problems slowly go away...how slowly is dependent on the housings themselves. The more imperfect the surface, the more breakin that must occur.