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After driving the car daily for a few weeks I have decided to remove the engine and subframe and transmission to correct a few issues.
The issue that required tearing things apart is that the car leaks about 3 drops of oil a day from the rear of the engine.
After checking a few youtube videos it looks like it has to be either the rear oil pan gasket or rear main seal or rear cover being warped, any of which require removing a bunch of stuff to fix.
Lots of people might say that a couple of drops a day is nothing to worry about and just drive it but the situation annoys me.
It leaks just enough that I have a slight burning oil smell every time I start the car to drive.
Edit: Found out that the oil leak is not from the rear seal but is actually the oil filter bracket weeping a small amount of oil as the oil pressure is elevated while driving around. It stops as soon as the engine stops and is very minimal when the car is idling hot, which is why I could not locate the leak exactly. The underside of the car has a light coating of oil on the rear half of the exhaust system and portions of the underside of the body. It should clean off with some de-greaser and elbow grease. The fix was to use some form-a-gasket on the face between the filter housing and the oil pan.
Now there is no reason for me to need to pull the engine other than to further clean up the wiring at the firewall area and the transmission items that need to be cleaned up.
While the drivetrain is out I can take care of the notchy shifting by adding a washer to the indent ball and install an aftermarket shifter and take a look at the clutch plate to make sure everything is playing nicely. The indent ball is on the top of the transmission and does not have enough clearance to remove with the transmission installed.
Also, while it is apart I can add a water temperature gauge and switch over to a 3 gauge pod.
One other thing I am contemplating is installing a more modern camshaft with lifters & springs.
Checking out choices on the internet shows that some that will give significant gains in output but be well mannered.
I would like to have one that gives a redline closer to the 7000 rpm indicated on the Miata tachometer, not that I actually rev that high while driving.
So far I have only run it up to about 5000 rpm a couple of times while entering the highway.
Something I noticed is that V8 Roadsters has a kit to relocate the heater core inlet and outlet to the passenger side that they utilize for V6 swaps. It uses AN fittings and braided lines.
If I get super energetic I might even remove the dash and switch to that style of hoses behind the dash. For some reason I have a worry that the copper tubing and fittings I soldered will start leaking in the future. No idea why I am worried but regardless, my brain has been chewing on that.
At the moment I am making a list and driving the car with the intention of removing the drivetrain during the cold part of Winter when I would not be driving the car anyway.
So far, not a bad fix list considering the scope of changes that have to be done to drop a V8 into a Miata.
Yeah, I had a rear main seal leak right after getting mine on the road. It was a new seal, but guess I didn't install it well enough out of the car - lol.
They do call for some dabs of silicone where the front and rear timing and seal covers meet the oil pan, that could be a point of leaking as well.
I've read on more than one build thread about people not liking the heater core outlet location. I stayed with the oem location and just found the right hoses to do the job, and tucked away properly now I don't even notice they're there. I'd really avoid any temptation to mess with the heater core hard lines at all which would create a very hot, smelly leak situation in the cabin, not to mention having to remove the dash just to fix it.
Where are you thinking of putting the water temp sensor. I tried the heater hose and the upper rad. the heater hose was about 15C cold and the heater hose about 10C cold.
Do you have a cam etal in mind? My car is already ridiculously fun to drive in town.
A location for the third temperature sensor is something that I have been thrashing around.
Because the ECU sensor is currently using the sensor location on the driver's side head, that has to left as is.
It leaves me with the passenger side head location which currently has the Miata gauge sensor screwed into it.
My current thinking is to see if the Miata gauge might actually work with the gauge sensor.
If it would, all that would be required would be to tee off the wire under the dash but my guess is that will not actually work.
Murphy's Law at work and that sort of thing.
If that does not work when I test it out then I will use the more accurate cylinder head location for the gauge and then put an adaptor somewhere in the heater hose near the engine connection point to get a less accurate reading for the Miata (nearly useless) gauge.
Edit: since in am going to pull the engine to fix the rear cover leak I am thinking of drilling and tapping somewhere on the water pump housing near the thermostat. From the outside it looks like there is some usable real estate.
I dont have the miata 'gauge' but if i remember correctly not having it connected is nearly the same as having it connected. The sensor i have is an 1/8ntp by the time i drill out an adapter for the sensor there not enough material left to screw it into the port in the right head.
The sensor I bought has several thread adaptors in the same package to work with various tapped hole sizes.
They are a flush style and so should not have any problems with installing deep enough to get a good Freon temperature reading.
I did debate not connecting it at all because it is useless but want all the factory gauges to work.
Edit,: None of the adaptors that came wit the gauge sensor have the correct threads to work with the LS1 head tapped opening.
Murphy's Law at work.
One hope is that someday somebody will come out with a replacement instrument cluster that has actual gauges and fits the dash correctly with no need to scab and modify.
Of course that is behind the hope that someday a vendor might come out with reasonable quality headlight covers that make use of good lighting so I can see at night.
A couple of pictures of the final product. Nothing much to see from the outside. Sleeper, just like I want it to be.
Open the hood and the view is nice. Tried to make it look as close to a factory look as possible. Just a nice clean 110k well maintained engine compartment.
And finally an interior shot showing the pillar pod with gauges. Other than that one modification and the aftermarket stereo everything looks stock.
Continental 205-45-Z16 all season tires.
Not sure what the wheels are as they were on the car when I bought it.
It works very well for me as a daily driver.
While I'm thinking of it, is that a oem Miata upper strut bar? Been meaning to look into whether it will work with the LS engines. Any issues installing it?
Presuming you are talking about the support that bolts between the two shock towers, no it is not a stock Miata support.
It is whatever Flyin Miata sells as their current brace with the sticker removed.
It fits well and seems plenty sturdy and stiff and well made.
For me it was sort of an afterthought because I don't drive hard and actually see no reason that it needs to be there but it looks good and keeps the front of the chassis squared and aligned. No reason to take a chance that the chassis could twist and warp in the future if a simple brace would keep that from happening.
The shop I work at has a couple of plasma cutting tables and plenty of scrap laying around and originally I figured on fabricating something but just like a bunch of other stuff, I got lazy and pushed the "easy" button by ordering something from Flyin Miata that I could have actually fabricated for myself.
It is one of the regrets that I have with my build and if I ever do another one I will go ahead and fabricate my own stuff for most of the build.
That way it will take much longer and give me something to do over a longer time frame than the 6 months that this one took.
I am already running up a list of what parts I intend to use for my next build (if that ever happens)
Now to get it tuned to work with the Corvette air intake sensor, something I can't do for myself.
The more I drive the car, the more annoyed I become with the Chevrolet factory shifter.
Originally I was figuring on driving the car till the weather gets cold and tear it back down during the cold part of Winter to take care of the couple of small issues (slightly leaking rear seal) that require removal of the engine and transmission to get at.
Compared to the original Miata shifter, the one that came with the T56 transmission just feels like crap and ruins the sports car feel while driving. It reminds me a bunch of the Mustang 6 speed shifter on the new car that I test drove before deciding to go with an automatic back in 2015.
The very short shift lever probably has a lot to do with the feel and stiffness of shifting since the Camaro lever is about 6" lg. while my lever to keep the **** in the factory location is less than 2" lg.
The best "Seat of the pants" comment I can give is second hand from my brother, who drives a beautiful red Honda S2000.
When I first told him of my plan to do an engine swap on my Miata in order to make it as quick as his S2000, he was very negative on the idea and tried real hard to get me to sell it and buy an S2000.
After looking at the swap and listening to the car and taking a short drive, he now gets it. He did say that the fun factor of driving my Miata is well above the fun factor of his S2000. Take that for what it is worth.
Only other real world comparison that I have is a little thing that happened last week while I was driving home from work on Friday.
A guy who drives a fairly new beautiful blue Camaro SS is on the same 2 lane road at about the same time as me quite often. Guess we both get off work at the same time. To make the story short, I was right behind him when turning right from the two lane to the 4 lane highway. We are both in the habit of rolling on the throttle as we "briskly" accelerate onto the highway and he will pull slightly away from my 2015 Mustang GT. He did his usual roll on but I pulled past him with the Miata. The roll on was from about 20 to (cough cough) 70 before both of us lifted as the speed limit is 65 on that stretch of road. He gave me a wave and a thumbs up.
That tells me the Miata is now measurably faster accelerating than my Mustang. Guess it is time to sell the Mustang since having two fast cars is redundant and the Miata is way more fun to drive.
Over the weekend I did something "interesting".
Not sure yet if it is good or bad, time will tell.
Went to the local SCCA Autocross event that was held in Tulsa yesterday.
Didn't run the car as I just feel it would be better to be more prepared before embarrassing myself and the car.
Turned out to be a smart move as it allowed me to focus on talking to the competitors and riding along.
After riding along with several Miata people making passes and talking to a bunch of people who know more about making a car handle, what I did decide to do is to set up the suspension to mimic the STR class but add some bigger brakes in case I want to do some of the Touring dates at the Hallett road race track, which is just down the road from my house.
The amount of cornering force that the wider & stickier tires allow over the stock class using normal street tires (what are on my car at the moment) just blew me away.
It gives me a direction to point for future modifications to make the suspension more capable of perhaps keeping up with the rest of the drivetrain.
The classification that the SCCA would put me into does not matter to me as long as they allow me to participate.
One thing I did do that did not pan out at all was to post over on the "other" Miata Forum was to ask about changing to an 18" wheel that would make use of the tires that came out on the new Civic type R since that car sat a new lap record at Nuremburg for a front wheel drive car.
Got a huge thumbs down and was told very firmly to stick with the tried and true 15" x 9" lightweight wheels and base my tire choice on the purpose I want the car to fulfill.
According to the recommendations, 12.5# 15" dia. wheels are a huge advantage over 20# 18" dia. wheels in order to keep the quick handling Miata in it's happy place.
It sure seems strange to me that in these days of 18" to 20" wheels being common on performance cars the old 15" wheels are the number one choice for Miata's.
Just about the only time I can remember when new technology is not the answer over old technology.
At least until I change my mind, it gives me a list of parts to install and a reason for doing so between now and March 2018.
Amazing how I seem to find stuff for the car that I just "gotta have".
....15" x 9" wheels and some usable street/track performance tires.
....Will have to roll the fender inner lip to work with the wheels.
....Street/track brake pads all around while considering if big brakes are really needed, EBC Yellow or Hawk street/strip.
....Already have stainless steel brake lines but need to turn my current rotors.
....Two different people who have done Hallett dates in their Miata's told me bigger brakes are not even needed but I am dubious that they were understanding the potential speed difference between a 140HP Miata and a 350HP Miata.
....DOT 4 brake fluid
....Front and Rear sway bars with adjustable end links. Will have to research how to adjust the sway bars.
....Already have V-MAXX shocks so that part is good.
....Already had a 4 wheel alignment done to Flyin Miata recommendations so that part is good.
....An upgraded MGW short throw shifter based on recommendations from the LS1TECH forum folks.
....Hard Dog roll bar that will work with my current stock seats and soft top but is SCCA approved.
....Need to enlarge the hole in one of my tow bar connection points and make a sleeve so the tow bar is still usable but will double as a track tow connection.
....work up a reasonably strong rear track tow connection. Should be simple as an L shaped bracket with a 2" dia. hole.
....Fire extinguisher with mounting bracket. Probably will buy the Flyin Miata item that attaches to the floorboard seat bolting locations.
good deal, sounds like you are going about it the right way. Been years since I autocrossed and never autoxed a Miata, but these cars are just made for dodging cones, and the point and squirt nature of our LS swaps, will make it a blast. Great way to learn the car, and step up to track days once you get more comfortable.
Reminds me I need to get some tow hooks front and rear for my track day.
Actually weighed the car this morning on the way to work.
There is a set of certified scales at the QuikTrip down the road.
2720 pounds with a full load of fuel and nothing in the car except the spare tire and a bag of tools.
Now I know and don't have to guess any more.
An engine related item that I asked about over on the LS1Tech forum has to do with my oil pressure.
It is running about 60-90 psi when cold and about 40-60 after warming up with 5-20 Full synthetic.
That seems a bit high to me for a completely stock engine but the feedback indicates that those numbers are just where you would want them to be.
GuessI am just used to old school small block Chevy engines running 15 psi at idle.
Actually weighed the car this morning on the way to work.
There is a set of certified scales at the QuikTrip down the road.
2720 pounds with a full load of fuel and nothing in the car except the spare tire.
Now I know and don't have to guess any more.
An engine related item that I asked about over on the LS1Tech forum has to do with my oil pressure.
It is running about 60-90 psi when cold and about 40-60 after warming up with 5-20 Full synthetic.
That seems a bit high to me for a completely stock engine but the feedback indicates that those numbers are just where you would want them to be.
GuessI am just used to old school small block Chevy engines running 15 psi at idle.
Wow, heavier than I always assumed, though I'm probably around the same with a rollbar, subwoofer, amplifier, but minus power windows, etc. I'm curious now to get mine weighed, though I have no idea where to find a place like that near me.
Your oil pressure sounds a bit high cold and hot, but probably not a concern. I have a VDO gauge in my instrument panel, not the useless Miata gauge. I'm probably 50-60 psi cold, and 20-30 at warm idle. You are running 5-20 or was that a typo? I run Mobil1 5w-30.
Yesterday I got the car tuned at XP Racing in Oklahoma City and mostly all squared away.
On 91 octane it did 315 HP at 5600 rpm with 335 torque at 4600 rpm.
A bit below my pre-dyno guess of 325 but still solid numbers.
The thing I am most happy with is the amount of torque even down at 3250 rpm.
The tuner mentioned to me that his machine reads a bit lower than some of the other machines around town but as long as the car is tuned properly and runs good I don't really care. Going for big numbers was never my goal.
Now that I know the weight I can figure a comparative number.
Way back when the car had the factory motor it weighed about 2700 pounds with me behind the wheel and put out about 100 HP at the rear wheels which calculates to;
27 pounds per HP.
Now that it has the V8 after tuning it weighs 2850 pounds with me inside and puts 315 HP to the rear wheel which calculates to;
9 pounds per HP.
Not quite super car performance but still ahead of the numbers for my 2015 Mustang GT, which calculates to 10.1 pounds per HP.
One thing that came out during the tune is that one of my oxygen sensors are intermittently failing. What I get for using the sensors that came with the motor. I will buy a pair of new one's so that particular problem goes away. It was the root reason for the car to run rich as it was dumping fuel every time the sensor quit reading.
Another thing during the tuning session was that the tuner was surprised at how well the Corvette intake flowed air. He had to try several times to change the mapping to allow for it and said that he was surprised how much adjustment was necessary.
In order to get the car tuned I had to drive 240 miles round trip, far and away the longest trip for the Miata since I bought it. Even with the added insulation and sound deadener the car is not fun to drive long distances at high speeds.
Drove the turnpike for all but about 10 miles at 80 mph.
Based on the fuel used I got a rough estimate of 26 mpg, mostly due to the 6th gear overdrive keeping the RPM below 2000 and allowing some good mileage. That even included whatever fuel was used for the dyno tuning session. Miata's are not real good about allowing consistent fills but the number should be correct within 10%.
Now on to my list of small projects to get everything as squared away as I can make it.
The biggies are to remove the engine to replace the rear crank gasket and get rid of the tiny oil leak and also to replace the crappy factory shifter with a good unit.
Bruce, Great report. Sounds like the car is about totally sorted out and ready for a major drive. One thing I do even after extensive sound mitigation work is keep a pair of ear plugs handy. Freeways equal ear plugs, particularly if the top's down as is usually the case. The 30 or so dB sound reduction is Nice!
Guess I will call this V8 Miata build Part 2.
There will probably be pictures of the process as there are a couple of items I want to fabricate and clean up while the engine compartment is accessible.
After driving the car for a couple of months I decided to tear the car apart over the long weekend and work on it over the Winter.
The biggest two items to address while it is apart are that the rear of the engine still leaks about 3 drops a day, presumably from the rear seal and the 4th gear syncro went out on the transmission.
Guess it is no surprise as the stupid CAGS thing that was on the 1998 to 2002 Camaro's forced a person to shift from 1st to 4th when just driving around normal.
All in the name of fuel economy.
My drive train was so stock that nobody ever bothered to spend 5 minutes and $20 to insert a CAGS eliminator when the car was new, which put a bunch of extra wear on the 4th gear syncro.
While it is apart I will go ahead and have the transmission rebuilt and upgraded to handle more HP in case I want to bump up the performance another 150 HP in the future. A place down near Dallas has a good reputation for upgrading the T56 while doing a rebuild. Will cost $1100 for the upgrade but once that happens along with a good shifter that part of the drivetrains should be bullet proof.
As part of the stuff while it is down I will replace all the gaskets and seals just to make sure nothing leaks.
Originally I wanted to keep just enough patina on the engine to make it look like a well maintained 100k engine so the car would look as close to stock as possible.
After getting it all together that look does not work because so much of the under hood stuff is brand new.
Based on that I will go ahead and clean up the engine to match all the rest of the new stuff.
The exterior will still stay stock looking to maintain the sleeper look as much as possible.
Because I have an LS1 V8 engine under the hood, 300 HP is the bottom end of the performance potential with lots of gain by just changing the cam and intake.
One thing I am also considering is changing out the cam and intake to supposedly gain 80-90 HP, which would put me close to 400HP at the rear wheels.
The car feels wicked fast to my seat of the pants.
There is no way the car needs it but it is one of those things that comes under the category of "Might as well while it is apart".
The other reason I might upgrade the camshaft is in case I decide to sell it after completion later this year.
My guess is that a potential buyer will be much more willing to pay for 400 HP over 300 HP.
Most people are not like me cause I think 300 at the rear wheels with a 2700 lb car is plenty.
"The other reason I might upgrade the camshaft is in case I decide to sell it after completion later this year.
My guess is that a potential buyer will be much more willing to pay for 400 HP over 300 HP.
Most people are not like me cause I think 300 at the rear wheels with a 2700 lb car is plenty."
I agree with all the above. My 5.0 in all probability is not at 300 whp, but it sure feels nice. On the resale possibility I think (V8 Miata fans) are likely not the most mature people you'll find. That said, our adolescent brains equate more as better, therefore 400 or 450 hp has to be Mucho better than 300 hp. Never mind most younger (potential) buyers will be woefully underskilled to safely enjoy all that excessive Power. Yep, 450 sounds about right.
There has been a bit of a break in my Winter Miata project.
My father died of old age a couple of weeks ago and the whole experience just left me with no interest in working on the car.
He is the first close family member that I have lost and it hit me much harder than I expected it would.
The situation was no surprise as he has been in and out of the hospital every couple of months with heart issues.
While in the hospital with a low blood pressure issue he got pneumonia and everything just spiraled down hill from there.
Now I am back at it and have a goal of getting the car back up and running by the end of March for a family reunion.
I seem to be having a bit of problem with slight antifreeze leakage where the tubing actually connects to the heater core.
If anybody has a good long term fix, please let me know.
The little clamp and O-ring that Mazda utilizes to seal the tubing to heater core connection is really crappy looking but so far as I can tell there is no way to get away from it.
My guess is that is a common leakage spot from looking at threads over on the Miata forum.
My current plan is to remove my seat and lay under the dash and see what I can do to (hopefully) seal up that connection.
When I first noticed that I have some antifreeze under my carpeting I was worried that my copper tubing was leaking but after putting a pressure test on the line, mine is definitely dripping at that joint.
Hopefully some silicon high temperature form-a-gasket slathered onto the joint in conjunction with the rubber o-ring will make the problem go away.
If that doesn't work the only alternative I can figure is to braze or weld the tube directly to the heater core, something very tricky that might very well do nothing more than make a mess and force me into throwing away a brand new heater core.
Good news is that the car is apart anyway so it doesn't cause me any real problem as long as I can easily fix the issue.
On the camshaft swap I have decided to wait a while before doing anything.
The engine works so well presently that I just don't want to get into it beyond changing out all of the oil seal gaskets.
Changing the cam would also force me to have the tune redone so for the time being I will drive it with the engine un-modified and simply enjoy the car with the transmission rebuilt and upgraded.
10-17-2017, 11:59 AM
