825 replies to this topic

[38bfast]

Being Michigan I just roll it outside in the freezing cold for a few hours then roll it back in and pop it off with a putty knife.

[Jamz14]

J~

Johnny, Thanks for posting this. Did this on my new build this weekend and worked perfectly. Did such a good job it popped the floor plugs as well and I will have to re seam seal them. But this worked great! Thank you.

[MPR22]

I'm pretty confident in the numbers.  The lap simulation is extremely accurate for predicting powertrain changes such as hp.  Now, the power curves used were just scaled by a percentage of baseline power data.  Might not be a perfect way of doing it as there remains a large hp difference at max rpm.  Close enough for this study though.

 

Additionally, this simulation assumes a no drafting situation.  Differences in power will have less effect on lap time if you're tucked in behind another car and using his draft. 

 

FYI, the power curves used for this sensitivity study are these:

Probably a little misleading as those are essentially parallel curves.  Most dyno sheets don't look like that between different year models, sometimes between same year cars.  Do the racing organizations use that program to level out the different cars?  It would certainly get you close and then it could be fine tuned.   

[speedengineer]

Probably a little misleading as those are essentially parallel curves.  Most dyno sheets don't look like that between different year models, sometimes between same year cars.  Do the racing organizations use that program to level out the different cars?  It would certainly get you close and then it could be fine tuned.   

 

Yeah this wasn't meant to be a comparison of the different years of miata, but rather just to determine the lap time sensitivity of HP changes for a given car.  HP data from a front running 99 car was used and then scaled, which is why they appear parallel. 

 

I would hope racing organizations use something like this as it would be very useful for equalizing cars.  Sadly I doubt they do.  I know they don't use this program, as it's something I wrote myself and haven't shared around much!

[MPR22]

Yeah this wasn't meant to be a comparison of the different years of miata, but rather just to determine the lap time sensitivity of HP changes for a given car.  HP data from a front running 99 car was used and then scaled, which is why they appear parallel. 

 

I would hope racing organizations use something like this as it would be very useful for equalizing cars.  Sadly I doubt they do.  I know they don't use this program, as it's something I wrote myself and haven't shared around much!

Certainly seems like it would be helpful in car development especially in NASA HP to weight ratio classes.  You could play around with all sorts of variables to see what gives you the best outcome.  We are slowly building a LS3 BMW 330 to race in NASA.  

[speedengineer]

Certainly seems like it would be helpful in car development especially in NASA HP to weight ratio classes.  You could play around with all sorts of variables to see what gives you the best outcome.  We are slowly building a LS3 BMW 330 to race in NASA.  

 

That's exactly how I've been using it for the last 3 years, NASA PTE setups!  It's worked well for arriving at an optimal use of points.  So many potential combinations....even more to worry about than the HP:weight classes. 

 

ST3 just had some interesting rules changes for 2016, if you haven't heard about that already.  Average hp calcs.  I'm not sure what I think about that. 

[Steve Scheifler]

I have seen similar simulation programs, even bought one once but long since lost the info through multiple PC changes. Trying to recall the name of that program, it included the name of the author, like Bob zzz's race simulator. On the tip of my tongue...

For the clubs to use something like this they would/should be obliged to confirm reasonable accuracy with real world testing. And then what track(s) do they use? With some effort it could certainly improve their ability to balance cars within a class but to do it well would require significant additional effort.

[speedengineer]

I have seen similar simulation programs, even bought one once but long since lost the info through multiple PC changes. Trying to recall the name of that program, it included the name of the author, like Bob zzz's race simulator. On the tip of my tongue...

For the clubs to use something like this they would/should be obliged to confirm reasonable accuracy with real world testing. And then what track(s) do they use? With some effort it could certainly improve their ability to balance cars within a class but to do it well would require significant additional effort.

 

I agree, it would definitely take some attention to detail in order to do a fair job balancing cars.  Probably will never happen, but it'd be neat!

 

Not sure if there is interest, but maybe sometime I'll create a thread discussing the lap sim in detail, how it works, strengths/weaknesses, and some examples? 

[speedengineer]

I grew tired of dealing with the interior so I spent Sunday pulling the mechanical bits out of the car.  Front bumper, AC system, radiator, intake, engine, transmission, etc. 

 

Tonight I pulled the motor apart. I'm getting better at this!  I've built two miata motors so far, this will be the third.  I was able to strip the engine down from long block to individual parts in under an hour.  The only thing I haven't done yet is pull the valves from the cylinder head.  All three of the motors I've disassembled had ~100k miles on them, but this motor was by far in the best condition, visually.  Camshafts looked perfect.  None of the main or rod bearings even had any nicks in them!  The last two engines had a couple bearing scratches, as well as small marks on the crank journals that had to be polished out.  This one is perfect.  Half tempted to rebuild it with the same bearings, haha.

 

 

 

 

 

 

 

 

 

[38bfast]

wow previous owner changed the oil regularly. 

[Mike Collins]

 

Tonight I pulled the motor apart. I'm getting better at this!  I've built two miata motors so far, this will be the third.  I was able to strip the engine down from long block to individual parts in under an hour.  

 

 

 

When you win your first majors with this budget build, you'll have to have the engine out, including valves out in well UNDER an hour.... Keep up the good work

[Bench Racer]

When you win your first majors with this budget build, you'll have to have the engine out, including valves out in well UNDER an hour.... Keep up the good work

Say what, curious, engine out in an hour, by whose rule?

[Mike Collins]

Say what, curious, engine out in an hour, by whose rule?

 

Doesn't take any of the "pros" very long to do it.  I watched David DelGenio have one out and in pieces in what seemed like minutes.  He had a couple of hand tools in his back pocket and never used a power tool and never went back over to his tool box.

[Bench Racer]

Come on Mike, I didn't question folks could take an engine out in an hour. Your comment indicated one would need to take the engine out in an hour. My comment was whose hour rule.

[speedengineer]

I've never heard of an hour rule either.  I think Mike was just busting my balls for not having also removed the valves from the cylinder head within that hour 

 

I would have removed them that night, but the last person that borrowed my (homemade) valve spring removal tool damaged it slightly, so I had to do a bit of repair on it.  Cylinder head pics coming shortly.

[speedengineer]

More pics of a very dirty cylinder head.  Yeah, yeah, these pics of stock parts aren't near as interesting to look at as fab work or building the motor, but I want to document the build fully, and that includes posting photos of the entire process!!

 

 

Here's a very DIY setup:  Cylinder head stand made from some scrap wood and PVC, head bolts drop through into the PVC to keep the head from sliding off, and the PCV doesn't scratch the aluminum.  Homemade valve spring removal tool.  I made that a few years ago when I needed to disassemble a head asap and didn't have time to order the tool off the internet.  Uses a ball bearing and everything, so compressing the spring is no work at all. 

 

 

 

Now for some random pics of the [dirty] cylinder head.  There does not appear to be any stray tooling nicks in the port casting so that's a good start!  Can't tell on the exhaust side yet though as there is too much carbon buildup. 

 

I wonder how close all the 99 cylinder head castings are to each other?  The last two I did were one and two years ago, and I can't remember them looking any different.  If anything, the factory plunge cuts appear to have removed less metal from the port that my previous heads, though it's tough to remember.  If so, I think that's a good thing?  Granted, of all the SM engine variants, the 99 head is going to be the least critical.  What I mean by that, is having a great flowing head matters least on the 99 because it is the most plate-restricted engine. 

 

 

 

 

[Bench Racer]

Jason, many on site are great a busting the family jewels.

 

Keep the progress report coming.

[speedengineer]

Jason, many on site are great a busting the family jewels.

 

Keep the progress report coming.

I saw that quick edit you made, hehe 

 

Yeah, my valve tool is somewhere in the middle of the $$$ arm type and the sketchy hammer method.  Works pretty slick, just takes a bit longer as you have to move it from valve to valve.

 

Lots more to come.  I mean, we are only about 20 hours into a 300 hour build 

[speedengineer]

General engine build procedure that I have come up with:

 

1)  Clean all those dirty parts!

2)  Inspect everything to ensure it's legal, cams specs, piston and rod masses, etc, etc

3)  Reinstall pistons/rods/crank and measure deck height from piston, as well as CC the piston in the block (need this info later and it's preferable to only have to bring the block to the machine shop once rather than first for honing and again for decking)

4)  Perform the cylinder head plunge cuts, relief cuts, and valve job

5)  CC the cylinder head

6)  Have the shop deck the block and shave the head to desired amounts to achieve the correct compression ratio

7)  Build up the bottom end

8)  Build up the cylinder head, lash the valves correctly, etc

9)  Final assembly

10)  Get that baby in the car and hope it doesn't break the dyno 

 

Just a general order to do things in, left a lot of the detail stuff out.  Feel free to let me know if I missed anything critical!

[Johnny D]

J~