Engine Rebuild

#1

I bought an engine/transmission from a local guy for $150. Both were pulled for an E36 swap with about 180k miles. Lots of oil leaking from the engine, didn’t smoke or burn much oil when it ran, tranny shifts fine.

My car has a lower mileage engine swapped in a couple seasons ago (~60k miles) and is starting to develop some nagging oil leaks. Runs great otherwise.

I was considering a winter project and thought rebuilding my spare engine (high mileage one) would be fun/interesting as I’ve never rebuilt one before. I know there probably isn’t much power to be gained from a rebuild in this case, and it is a spec series so there are no “tricks” per se, but what should I consider doing? What would be worth my time and money? Simple rebuild? Send the block and head out to a machine shop? Any advice is appreciated.

#2

I was knocking around this idea too. Are there ways that a leak down test, or other tests can help you reach conclusions like…“the rings are good but the head needs work”, or “It looks like I need both rings and head work”.

Is overboring a machine shop project because handtools won’t bore straight enough?

How much hp is likely to be gained by going thru the hassle and expense of overboring the cylinders by the allowed .02" and putting in larger pistons? What is that likely to cost? My math indicates that .02" over bore will give you an additional .06 liter of displacement for a 2.4% advantage, call it 4hp? 4hp of straightaway talent would be pretty cool.

#3

If you search I made this same post about a year ago. After taking apart the block and still being able to see the cross hatching in all cylinders. Overbore and new pistons just does not seem needed. I would take it apart take it to a machine shop to have it hot tanked, cylinders honed, new freeze plugs installed, have the crank, rods, pistons checked out, and the head rebuilt. Then just put it all back together with new rings, rod, main bearings, seals, and oilpump.

If your motor is from a timing belt car, and the pistons are damaged I would go ahead and do the overbore, because oversize pistons are cheaper then stock.

#4

It’s not so much that overbore might be needed. This is just fishing for a winter project. It’s more about cost, benefit and hassle.

The problem here is that I really don’t know what I’m doing. I could get the job done by working with one hand and holding a book with the other like any other mechanically inclined American boy, but I’m sure that rebuilding a motor is one of those things that there’s years of tricks that separate the knowledgeable builder from a goof ball like me.

The first time I replaced a set of E30 brake pads it took me an hour, most of which was spent trying to compress the damn piston. Now I can do it in 10min because I know what I’m doing.

At this point I’m just trying to size up the scope of this project to determine if it’s do-able, entertaining, and worth doing. And I need to have a smart plan such that I end up with a motor that is better then my seemingly perfectly adequate current 175k mi. motor.

Any recommendations on a really good book for this? Another darn useful thing would be if someone could point me towards some long ass document entitled “I rebuilt my motor last winter, and this is what I should have done differently”.

#5

Maybe I came off like I knew what I was doing, I have gotten to the take the motor apart stage. Then funding for building my race car and finishing the rebuild that I don’t need yet had an altercation. I was just relaying info and advice I was given. There will really be no way to tell the extent of the rebuild until you tear the motor apart.

Mechanically inclined American boy,

Greg

P.S.
the first brake job I did only took half an hour:P

#6

87isMan wrote:

You’re smarter. I’m better looking. I can get smarter.

#7

Ranger wrote:

[quote]87isMan wrote:

You’re smarter. I’m better looking. I can get smarter.[/quote]

maybe, but can you get younger;)

#8

87isMan wrote:

[quote]Ranger wrote:

[quote]87isMan wrote:

You’re smarter. I’m better looking. I can get smarter.[/quote]

maybe, but can you get younger;)[/quote]

Now that was a sucking chest wound. That’s the last time I screw with you. Damn did I just get my ass kicked. Excuse my while I withdraw into my mancave and nurse my wounds for a bit.

#9

Since this is a Southeast Spec E30 duel, isn’t one of you supposed to accuse the other of dating men?

Steve D.

PS - Ranger - Nice developing cover story for your big $ cheater overbore motor that you’re going to show up with next year. “Aw, shucks, fellas! I was just messin’ around in the garage this winter and rebuilt me a junkyard motor with some cheaper pistons…”:stuck_out_tongue:

#10

Steve D wrote:

[quote]Since this is a Southeast Spec E30 duel, isn’t one of you supposed to accuse the other of dating chickens?
[/quote]

Steve,

Your standard is too high. I fixed it for you.

#11

Ok, this is all cute and amusing, and god knows I’m all for useless mildly amusing posts, but lets get back on topic. Lay some of the engine rebuild experience on us. And point us towards some good books and collections of tips/techniques.

#12

I think you’ll find that the people that know all of these tricks are loathe to part with them for free since in many cases they use them to earn a living.

In terms of education, try circle track (magazine), race car engineering (mag), The Design and Tuning of Competition Engines (book), Hot Rod, etc.

None of these will say “Here is a step by step guide to building an E30 motor” but you’ll gain a better appreciation for how everything works and why. Then you can draw your own conclusions from there.

We’re extremely limited in what we can do obviously by the rules. Someone posted a 170hp number legally, I’d be curious.

That is my main problem with the dyno numbers. If you build a legal motor and show up high on the dyno which set of rules ‘win’? Does the dyno trump everything? In which case why have the engine rules to begin with just state the number.

People will laugh at 170 as impossible since ‘average’ rebuilds seem to put out 155hp, but I don’t think anyone has gone 110% F1 style on this thing like a Sunbelt or other pro builders in the Miata world have.

#13

Ranger wrote:

Ranger -

Here’s the kitchen math I used before I selected the “take the one out of the rolled-over parts car” method of engine rebuilding.

84 mm bore, 75 mm stroke. 84 mm = 3.307087" +0.020" overbore = 3.327087", or 84.508 mm, or 56.08996 cm2 x 7.5 cm stroke = 420.7 cm3 displacement X 6 cyl = 2.520 liters. The same calculation for stock yields 2.490 liters (yes, I know the stated displacement is 2.494 but I am going for apples-to-apples here).

0.03 liter gain = 1.2%. Assume 155 hp for a baseline legal motor, 1.2% = 1.9 horsepower. However, relationship between displacement and power are not linear, are they? So let’s say 1.5 horsepower in practical application?

But I could be wrong. :wink:

Steve D.

#14

Steve D wrote:

[quote]Ranger wrote:

Ranger -

Here’s the kitchen math I used before I selected the “take the one out of the rolled-over parts car” method of engine rebuilding.

84 mm bore, 75 mm stroke. 84 mm = 3.307087" +0.020" overbore = 3.327087", or 84.508 mm, or 56.08996 cm2 x 7.5 cm stroke = 420.7 cm3 displacement X 6 cyl = 2.520 liters. The same calculation for stock yields 2.490 liters (yes, I know the stated displacement is 2.494 but I am going for apples-to-apples here).

0.03 liter gain = 1.2%. Assume 155 hp for a baseline legal motor, 1.2% = 1.9 horsepower. However, relationship between displacement and power are not linear, are they? So let’s say 1.5 horsepower in practical application?

But I could be wrong. :wink:

Steve D.[/quote]

Or it could be dyno error. There are tricks and there are tricks. The best way to know is to do your homework. Thankfully the series has to use a stock ECU which, for the most part, limits the top number. So how do you check for ECU tampering? Come out to a dyno day and compare notes with some of us that have been doing this gig for a while and will discuss the tips to keep everyone honest.

Regards, Robert Patton

PS Jim Robinson is correct about the pro shops, but often (if you buy them a beer) you’ll learn more than you want to know.The series is going in the right direction in setting “cap” numbers and I’m trusting that Hunt establishes a fair variance model from which we can operate.

#15

Steve, your math is right, mine is wrong. I used .02" squared as if was a radius, but no, it’s a diameter. That makes it pretty clear that overboring would be a helova big expense for the return.

Jim and Robert, I’d love to hang out at pro shops and hang out with you guys on dyno day. But Savannah isn’t the place to do either. Now get a dyno day that is contiguous with an event at RA, and that I can make happen.

#16

The nice version is that the dyno limits what you can have while the engine specs limit how you can get it.

The mean version is that you cant know if someones cheating or not without tearing down their motor, so we need a better rule to help make sure they cant.

I dont see any conflicts between the rules.

#17

You also don’t see any conflicts between the people making the rules being the same that are enforcing along with being participants with no checks and balances between the groups.

So I build a 100% legal motor to the rules outlined I go to the dyno and make 160hp and the ‘limit’ is 159hp. Lets say for arguments sake there is time penalty of 1 sec. Which means now instead of winning this theoretical race I’m now 10th. I say “Balls to that tear it down I’m legal”. The motor is torn down and nothing illegal is found, but I’m still penalized because of the dyno? How exactly does that work.

#18

We need the two rules.

If we have just the build specs like we do now, guys can come to the track with 168hp. Whether they are cheating or not can not be found without tearing down motors (not an option). The series is not as competitive or cheap with a huge advantage like this (legal or not) so adjustments to the rules should be made.

If we just have the horsepower cap, guys could come to the track with chevy big blocks with pinhole restrictor plates or high strung little 4 cyl. engines that weigh less (exaggerating but you get the point). Even if they have the same power on the dyno, from what I understand there are a lot of other advantages to be gained.

Your example does not work because your theoretical driver broke the hp cap rule. It wouldnt matter if his motor is built to spec or not. The engine specs just limit how you are allowed to meet the limit. That doesnt mean you will be able to build a spec motor that exceeds the limit. This prevents the spec miata type problems of spending huge money for a few extra hp.

Having officials that race is an advantage. Cobetto for example always has a great undertanding of our problems because he races with us. If you think these guys are abusing their power, you’ve probably never raced/talked with them before.

#19

So you take rule (set) one which is measurable, repeatable, consistent and out pops your motor.

Then you take rule two which is arbitrary, inconsistent, and variable to test said motor after it has already been built.

Perfect. I’m sure all this stuff will be figured out and implemented perfectly after all the exhaust rule went so well why would anyone complain.

Here is another idea - use the dyno as a guideline. If you pull a 175 and the cap is 160 you can take your penalty or opt for the tear down. If you’re legal fine if not you take your lumps. Then it is up to the powers that be to figure out if you’ve exploited a loophole and write a rule to cover it.

And again I’ve met Carter and I’m sure Chris is a nice guy just like Pantas and Chuck. No problems racing with them either. However it is clearly a conflict of interest to have the people administering the series in direct competition with everyone else. That is my only point, and since you can look at examples of this in any other serious racing league I feel on pretty solid ground. Otherwise why wouldn’t ALMS just let Penske write the rule book and enforce the rules, I’m sure he is a heck of a guy, probably a good dude to have a beer with. Checks and balances, and more insight into the rules discussions are a possible answer.

#20

Since people had such a great time with the spec exhaust like you say, I’m sure they’ll have no problem with taking out their motors (costing them time, price of fluids, and use of their racecar), paying to transport the motors to some far away shop (not of their choosing), waiting weeks for it to be torn down (hopefully by someone who knows what they are doing), then finally getting it back hopefully in the same condition in which it arrived (a few hundred dollars later), while the rest of the region gets to wait for weeks to hear the official race results.
I think most would agree that tear-downs are out of the question.

We will probably have issues with the dyno and I’m sure we’re going to have a lot of angry drivers in '09. And of course there will be some guys saying “I told you so” but I haven’t heard any better ideas.