What do you start with when building an engine? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 07-13-2009, 01:38 AM   #1
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: May 2007
Location: Austin, TX
Posts: 1,923
Total Cats: 0
Default What do you start with when building an engine?

Had a discussion earlier about how different people are building their motors. The conversation was exactly what you would expect when it comes to pistons, rods, etc. What really stumped me was which would be the best way to start if you were starting with nothing. I'm curious if finding a blown motor for cheap, unknown condition junkyard motor that runs, spending more money to get a good runner, or something I'm not even thinking of would be best. So, if you were starting to do a build today with nothing, which route would be best and why all while trying to do this on a minimal budget?
JayL is offline   Reply With Quote
Old 07-13-2009, 01:44 AM   #2
Senior Member
iTrader: (7)
 
Join Date: Aug 2007
Location: Southern Indiana
Posts: 1,371
Total Cats: -1
Default

I, personally, started with a junkyard motor. I was told it was in running condition. I paid $300 for it.
wes65 is offline   Reply With Quote
Old 07-13-2009, 02:03 AM   #3
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

find a junk yard motor pull the plugs etc and inspect the block before delivery for big ****** holes etc and go from there. These babys are pretty stout short of the extra ventilation like what wes and others have done nothing is gonna get screwed up that you where gonna keep anyway.
magnamx-5 is offline   Reply With Quote
Old 07-13-2009, 02:10 AM   #4
Elite Member
iTrader: (10)
 
Join Date: Oct 2008
Location: Seattle, Wa
Posts: 1,780
Total Cats: 30
Default

Last time I built one, I started with a tired old running motor from my parts car. Blown motor on the cheap means you can run into unforseen problems like needing a new/reground crank if the bearing were too trashed or being unsalvagable due to excessive cylinder wall damage. Buying good running motors is a safe bet, but tends to be a little pricy for me if its just going to serve as a core anyway.
Jeff_Ciesielski is offline   Reply With Quote
Old 07-13-2009, 02:11 AM   #5
Elite Member
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

I have a few questions about this because i just so happend to be in the market for something.

1. What do you check first in a motor to know if its good?
A. Cam caps- If the cam caps have some scoring how much would it cost to get them micro
B. Oil- Can there be anything in here that would turn you away? Rust particles or major shavings?
C. Turn the crank to verify that it moves- If it doesnt move then the motor is obviously siezed right?

What else do you look for in the head to check if its bad?

Anything else you would add?
SKMetalworks is offline   Reply With Quote
Old 07-13-2009, 01:22 PM   #6
Elite Member
iTrader: (7)
 
samnavy's Avatar
 
Join Date: Apr 2006
Location: VIRGINIA BEACH, VA
Posts: 6,020
Total Cats: 175
Default

POWER GOAL?
USE?

No junkyard is going to let you do more than (MAYBE IF YOU SHOW CASH) pull the valve cover to let you inspect an engine. There's only so much you can tell by looking down the spark plug holes too.

I rememeber reading that 94-95 engines were preferable for some reason (maybe lower compression) and obviously a '99-00 head is the only way to go. I can't think of any "special" years for blocks or cranks that would make one year better than another.

Find a machine shop in your local area and go down there and talk to the guys, get a feel for their competence and have a look at the shop. A clean shop that looks safe and is well organized is a good bet... although sometimes the best work is done in a place you wouldn't let your dog sleep.

Hustler will chime in here I'm sure with some good advice. I think he says that a full balance is worth every penny.

For the 300whp range and stock rev limit, a 99-00 low mileage head that's been checked good by a mechanic... bolt it in stock and be happy. I'd love to see some flow charts of a regular 1.8 head that's got a p&p, oversized valves, 5-angle, etc... vs. a stock 99-00 to see exactly what your extra $1500 buys you. Above that power and RPM, it starts making sense to spend the extra money on head-parts (your budget is probably bigger too)... but I'd still start with the better flowing head.
samnavy is offline   Reply With Quote
Old 07-13-2009, 02:30 PM   #7
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: May 2007
Location: Austin, TX
Posts: 1,923
Total Cats: 0
Default

This project isn't one of my own (yet, but it's getting me interested in doing something like this), but for a local guy. I have a couple engines sitting in my garage that I would like to get rid of. He might be interested in one of them, but I don't want him to buy something that won't be in his best interest. If one of them would be a good starting point for his project I want to be able to share this information with him so he can make an educated decision. If not, then I want to be able to point in in the right direction.

This would pretty much be a budget build to put in a track car. Around 300 or so at the wheels would be the power goal.

Engine one sitting in my garage: 01 engine with 22K and has had a turbo on it since pretty much day one. VVT head is not something that he wants and the fact that he would be paying for a running motor makes me think this isn't a good choice.

Engine two sitting in my garage: 99 engine with unknown mileage. It quit while driving and when the previous owner brought it to a shop was told it had seized and required replacement. It turns over just fine so I don't think this to be the case, but nobody knows. The oil is dirty and the previous owner definitely didn't take maintenance seriously. I think this would be a good candidate since he will be taking everything apart and building it. What's a fair price for this motor if he was to go this way?

Or keep looking for something else (what and why?).

Any help would be appreciated.
JayL is offline   Reply With Quote
Old 07-13-2009, 02:42 PM   #8
Elite Member
iTrader: (30)
 
Join Date: Aug 2007
Location: Va Beach
Posts: 7,282
Total Cats: 0
Default

I built the motor that was in my car. If he has another car to drive then that's the best way imo.
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
levnubhin is offline   Reply With Quote
Old 07-13-2009, 02:50 PM   #9
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

I'd go with the 99 just so you don't have to jack with VVT. Just take a look at the cam journals. If those are fine then it is a good candidate for a rebuild (unless there's a hole in the block or something). Its easier to deal with line-boring the crank than the head...supposedly. Crack it open and check for scoring.

If all wear items are replaced, then either motor works. I'd say $400 is fair...not a smoking deal, but fair for a motor that came out with the symptoms you described. Now, if you crack it open and check for scoring on friction surfaces and verify that it looks good, then you can ask for $500 or so. An engine that only needs a valve-job and a cylinder bore is worth more than one that might need line-boring on 3-shafts.
hustler is offline   Reply With Quote
Old 07-13-2009, 03:35 PM   #10
Elite Member
iTrader: (15)
 
Join Date: Dec 2007
Location: San Antonio, Texas
Posts: 4,889
Total Cats: 28
Default

If you know a REPUTABLE machine shop you plan to use for your build, then you might ask them if they deal with a good boneyard for parts. They could get a motor for you, then if they tear it down and it is junk, then they could deal with their buddy at the boneyard to find another one. This gets you out of the middle of the finger pointing process.
ZX-Tex is offline   Reply With Quote
Old 07-13-2009, 03:38 PM   #11
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: May 2007
Location: Austin, TX
Posts: 1,923
Total Cats: 0
Default

I'll pull a few more cam caps and take some pictures later today or tomorrow. We pulled a couple of them last night and there appeared to be some signs of wear to my untrained eyes. Probably from the lack of oil changes. I've only looked at stuff that was new so I'll let the pictures do the talking.
JayL is offline   Reply With Quote
Old 07-13-2009, 05:25 PM   #12
Elite AbsurdFlow Member
 
Laur3ns's Avatar
 
Join Date: Mar 2008
Location: Enschede, NL
Posts: 2,058
Total Cats: 11
Default

So does a full 99 engine, drop in a 94 chassis without issues or do you need to mess with oil pressure senders, starters, alternators, PS, etc? If it's a drop in, I might be tempted to bite on a deal for a 99 engine and build it for when I blow my current engine. If it's a larger project than dropping in a 94 engine, I will just do that.
Laur3ns is offline   Reply With Quote
Old 07-13-2009, 07:09 PM   #13
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by JayL View Post
I'll pull a few more cam caps and take some pictures later today or tomorrow. We pulled a couple of them last night and there appeared to be some signs of wear to my untrained eyes. Probably from the lack of oil changes. I've only looked at stuff that was new so I'll let the pictures do the talking.
If you can feel scoring, you have problems. If the car overheated and stalled...then just go ahead and melt it down because its over.

My buddy's shop had a car show up that overheated so bad that the cams snapped. lol
hustler is offline   Reply With Quote
Old 07-13-2009, 08:12 PM   #14
Elite Member
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

Quote:
Originally Posted by hustler View Post
If you can feel scoring, you have problems. If the car overheated and stalled...then just go ahead and melt it down because its over.

My buddy's shop had a car show up that overheated so bad that the cams snapped. lol

What are the signs of a overheated head? Anything else you can check for besides head warpage and cam cap scoring?
SKMetalworks is offline   Reply With Quote
Old 07-13-2009, 09:27 PM   #15
Elite Member
iTrader: (9)
 
Join Date: Aug 2006
Location: Concord, North Carolina
Posts: 4,172
Total Cats: 5
Default

Why is everyone here afraid of VVT? Get an EMS that can control it and enjoy the extra power down low.

Freaking Y8s dyno should be enough to point that out.
miatamania is offline   Reply With Quote
Old 07-13-2009, 09:38 PM   #16
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by miatamania View Post
Why is everyone here afraid of VVT? Get an EMS that can control it and enjoy the extra power down low.

Freaking Y8s dyno should be enough to point that out.
what compuer controls it? I was under the impression that y8s upped boost at high rpm to compensate for the valve timing.
hustler is offline   Reply With Quote
Old 07-13-2009, 09:39 PM   #17
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by sbkcocker499 View Post
What are the signs of a overheated head? Anything else you can check for besides head warpage and cam cap scoring?
well, you can look at the valves for uneven coloration / burning indicating leakage thorugh the valves.
hustler is offline   Reply With Quote
Old 07-13-2009, 09:45 PM   #18
Elite Member
iTrader: (12)
 
Join Date: Aug 2006
Location: Central-ish VA
Posts: 4,449
Total Cats: 16
Default

Quote:
Originally Posted by hustler View Post
what compuer controls it? I was under the impression that y8s upped boost at high rpm to compensate for the valve timing.
He had Hydra which controlled it, and now has adaptronic which can control it. You should really check his dyno thread again where he shows the effects of vvt on tq curve. Its pretty amazing.
neogenesis2004 is offline   Reply With Quote
Old 07-13-2009, 10:35 PM   #19
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,037
Total Cats: 406
Default

Quote:
Originally Posted by hustler View Post
what compuer controls it? I was under the impression that y8s upped boost at high rpm to compensate for the valve timing.
you must have missed it i guess. probably sitting in the corner shaking wondering if 8.6:1 compression was going to make your car a dog.

anyway, at the same boost level, advancing the intake cam gained me at least 30 ft lbs (max 40ish) from 3k to 4k with positive gains from 2500-4500. similarly retarding the cam at the top end made a difference of 60 hp.

look at the graph again:
http://y8spec.com/dyno/taleoftwoturbos.jpg
green = retarded
red = advanced
both runs are at 9.5 psi. same dyno, same day. mixture was not ideal due to the drastic changes in VE.
basically the VVT allows me to take the tallest curve on each side. red on the left, green on the right.

here's a comparison of the idealized VVT curve from those two graphs and photoshop (though in practice it should be the same) against TurboTim's twins. I forget what boost he was at.
http://y8spec.com/dyno/twins_vs_2876.gif
y8s is offline   Reply With Quote
Old 07-14-2009, 11:19 AM   #20
Junior Member
 
Join Date: Aug 2008
Location: MD/DE/PA
Posts: 337
Total Cats: 0
Default

Step 1- Find a motor that doesn't have a rod sticking through the block. In the case of Miata engines, this is pretty damn easy, especially for NAs, since they aren't worth much and get totaled without much damage, and therefor the engines have more life than the chassis they're in. That said, going with a junkyard motor, even if it doesn't have any OBVIOUS damage (like the aforementioned rod through the aforementioned block), it could have been severely overheated, etc., you just don't know. You could go to a more reputable recycler, whether Miata-specific or not, many will check the engines over for compression, etc., so you have a better idea what you're getting. Of course this costs more. Balance cost vs. gamble according to your own findings.

Step 2- Determine goals/budget. If you're planning relatively low boost or whatever, don't bother with really expensive components. Then again, if you HONESTLY believe that you'll be going to higher power levels, it's silly to build the motor and then have to build it again. Only you can make this determination. I've seen this go both ways- people having to yank a motor to build it up more after a mild/stock build within only a few months/years as they became bored, and people building fairly exotic motors that are WAY overkill for what they're doing. Then again, if money is no object, then go with the best components money will buy. For the rest of us, we have to determine what will comfortably do what we need to do without breaking the bank.

Step 3- Find good machine shop. For Miatas, spec Miata builders are a good place to start. Ask intelligent questions and see how they respond. Don't go with a shop that doesn't bother to take the time to figure out your needs, but also don't go wasting their time asking a million stupid ******* questions that you could easily Google. Personally I don't worry about clean/organized vs. not- I look to see the results of what they've built. One shop I know of doesn't look like anything, and I think only two of the workers speak English (they're all really nice guys), but they build some of the best rotaries around. Most shops are more than happy to brag of their (customers') accomplishments if you ask- so ask.

Step 4- Figure out how much assembly you're comfortable doing. Building an entire motor by yourself is cool, but not if you **** it up. Then it's just expensive.

Step 5- Spend money and wind up with built motor.



Quote:
Originally Posted by Spookyfish View Post
So does a full 99 engine, drop in a 94 chassis without issues or do you need to mess with oil pressure senders, starters, alternators, PS, etc? If it's a drop in, I might be tempted to bite on a deal for a 99 engine and build it for when I blow my current engine. If it's a larger project than dropping in a 94 engine, I will just do that.
Srsly?
the_man is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
elesjuan's mediocre 95 Miata adventure (google fiber edition) elesjuan Build Threads 8 02-16-2016 09:36 PM
The "just have fun build" nelson8708 Build Threads 9 09-26-2015 10:07 AM
In what world... curly MEGAsquirt 11 09-22-2015 12:54 PM
AFR Not showing anything eunosgippa MEGAsquirt 0 09-09-2015 06:19 PM
ME221 Now has Autotune and Long Term Fuel Trim Tables Motorsport-Electronics ECUs and Tuning 0 09-05-2015 09:02 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 12:25 AM.