825 replies to this topic

[Danny Steyn]

Fixed:

 

 

Nothing says "premium luxury" like tan interiors.  lolol

 

This complies perfectly with the Steyn Best Damn Spec Miata Build that also complies with Mrs Steyn's philosophy that it is not how good you are but how good you look. Glad to see the build heading in the right direction

[Todd Lamb]

If nothing else, it is more accurate than the other graph;)

[Diller]

fire hazard

 

 

And the plastic in the dash isn't? Automotive grade "suede" is self extinguishing anyway.

[speedengineer]

I think I'm going to try keeping the tan dash.  If I later decide I don't like it, I have the option of swapping to a black dash, or coating the tan as some have suggested. 

 

Been working on the drop floor pan.  Most of it is done.  All except for the front edge, a couple trim pieces, and some more welding.  I will be leaving the front edge incomplete until after my seat arrives - I may need to notch out the trans tunnel more (forward of the front of the dropped floor pan) in order to get the seat far enough to the right.  No point in doing a bunch of work finishing the front of the floor pan, only to have to cut it out and redo it later. 

 

I did take a moment to set a spare Recaro seat I have laying around on the new floor pan.  Holy crap does it feel like I am sitting low in the car, can barely see out the front window.  Checked head clearance to the roll cage, there is a LOT of room, 5+ inches since there is no helmet or roll bar padding. 

 

 

There needs to be a stiffener c-channel at the bottom of the drop seat, or else the floor will be too flimsy.  I choose to fabricate a new one, as the oem floor stiffener had apparently been used as a jacking point at some time in it's life, and the less undercoating I have to scrape off, the better.

 

 

Rear section bent up and tacked in place:

 

 

The floor pan itself:  Btw, electric sheet metal sheers are awesome.  Should have bought one years ago.

 

 

Floor pan partially complete and mostly welded into place.  I'll finish the front edge after I test fit my seat. 

[Steve Scheifler]

I'm not sure about the NB cars, but something you will want to test fit is the exhaust. On the 1.6 where the down pipe ends can make it very difficult to notch the tunnel that deeply and still get the exhaust around it.

[dstevens]

 

The floor pan itself:  Btw, electric sheet metal sheers are awesome.  Should have bought one years ago.

 

 

 

Looks good.  Shears are great though a plasma table is pretty good too...  You look like you could use a good plasma table in that shop. 

[38bfast]

From the looks of it you may have gone a bit too far inboard. Distance from the outbord sill to the inboard tunnel notch should be no more than 18.25. That gives clearance to a SD style exhaust.

[speedengineer]

I'm not sure about the NB cars, but something you will want to test fit is the exhaust. On the 1.6 where the down pipe ends can make it very difficult to notch the tunnel that deeply and still get the exhaust around it.

I did test fit with the exhaust I have and it appears to clear fine.  Difficult to tell for sure without the powertrain in the car - can't tel exactly where the downpipe ends and where the prop shaft sits.

 

Looks good.  Shears are great though a plasma table is pretty good too...  You look like you could use a good plasma table in that shop. 

Ha!  That's a slippery slope!  I could use a lot of stuff in the shop, plasma being one of them.  And then I need a plasma table.  Then I'll want a better air compressor setup, and then something else, and then I'll need a bigger shop to hold it all 

 

From the looks of it you may have gone a bit too far inboard. Distance from the outbord sill to the inboard tunnel notch should be no more than 18.25. That gives clearance to a SD style exhaust.

I am exactly 18.25" at the front side.  Rear is 19" and I chose this as it best matched the trans tunnel width higher up on the tunnel (tunnel is narrower in the rear).  In hindsight I probably could have gone 18.25" in the rear also and made it work. No benefit to wider in the rear as seat mounting width will be limited by the front side anyway.  I'm not using a springfield dyno exhaust, but out of curiosity, where is the tight spot, at the front or at the rear?

[Jim Drago]

Fixed:
 

 
Nothing says "premium luxury" like tan interiors.  lolol

Gone for a few days and you miss all this cool stuff I miss!

It is a sin to ever run a tan interior in a Spec Miata! I make my guys pull only black dashes as I hate tan that much.. paint/dye if you are starting with tan.. Your graph is wrong, tan dash is .5 a lap slower than painting the cage the same color as the rest of the interior. IMO.

By the way, this is one of my favorite threads in a long time, we except for all the parity threads, those are my favorites

[38bfast]

exhaust runs on the x axis of the car so it will be tight in the rear on your build. remember you have to put in the belt mount on the rear as well witch will go further inboard. A SD type system will be off your option list. 

[speedengineer]

Gone for a few days and you miss all this cool stuff I miss!

It is a sin to ever run a tan interior in a Spec Miata! I make my guys pull only black dashes as I hate tan that much.. paint/dye if you are starting with tan.. Your graph is wrong, tan dash is .5 a lap slower than painting the cage the same color as the rest of the interior. IMO.

By the way, this is one of my favorite threads in a long time, we except for all the parity threads, those are my favorites

Haha, thanks Jim.    #TanDash, it's trending 

 

exhaust runs on the x axis of the car so it will be tight in the rear on your build. remember you have to put in the belt mount on the rear as well witch will go further inboard. A SD type system will be off your option list. 

Just fit up my exhaust again.  My muffler is shorter than SD, ends halfway back on the floor pan, so no clearance issues at the back, but still a little tight in the middle.  It would be an easy fix to tuck the rear in a little - Use a cutting wheel to cut out the bend in the sheet metal from the rear of the pan up to the middle of the pan.  Then pull in the sidewall 3/4" at the rear, tack weld.  Then bend up the floor pan around the outside of the sidewall, fully weld.  Question is, is it worth doing all this just to package-protect for future exhaust options?  Probably.  Ugh.  This project is going to be about $36 in sheet metal, and about $999 in welding supplies, haha. 

 

Regarding seat belt mounts, couple options.  Could do the standard thing which is use the eye bolts that come with the schroth harness, through-bolt through the trans tunnel.  But then as you mentioned, there is a bolt end sticking out taking up clearance.  Other options are to weld on a beefy bracket to the trans tunnel and either clip the harness directly to it, or install the eyebolt in the bracket.  Alternatively, use very strong seat brackets, and incorporate an eye bolt in the seat bracket for the harness to clip to.  I rather like that idea, as then if you relocate the seat, the harness mounting geometry remains correct to the harness holes in the seat.  I've read through all of the schroth harness mounting instruction (long document) and see no mention of it being a bad idea to mount directly to the seat brackets.  They are specific about keeping the lap belt as short as possible, and mounting points being no wider than the width of the seat.  Mounting the harness to the seat bracket would accomplish this. 

[dstevens]

I'm not using a springfield dyno exhaust, but out of curiosity, where is the tight spot, at the front or at the rear?

The SD is what most of the fast guys use and many of the rest of us use as a base for building something.  The Magnaflow is pretty easy to source and not too expensive and you can get the tubing from Summit or have your local silenciador shop bend it up for you.  In the rust belt they probably call them muffler shops...

 

You might save $100-150 out of pocket (if you can get it close to right as possible the first time) but as we used to say in the big time roadie business, it's a false economy.  At the end of the day in a 15k car you don't really save anything.  It probably costs you in terms of time to build and more importantly performance.  The SD exhaust will be some of the best $300 you've spent. 

 

I did my tunnel notch too far inboard the first time and had to cut it out.

[pitbull113]

#tandashlivesmatter

[Rob Burgoon]

Haha, thanks Jim.    #TanDash, it's trending 

 

Just fit up my exhaust again.  My muffler is shorter than SD, ends halfway back on the floor pan, so no clearance issues at the back, but still a little tight in the middle.  It would be an easy fix to tuck the rear in a little - Use a cutting wheel to cut out the bend in the sheet metal from the rear of the pan up to the middle of the pan.  Then pull in the sidewall 3/4" at the rear, tack weld.  Then bend up the floor pan around the outside of the sidewall, fully weld.  Question is, is it worth doing all this just to package-protect for future exhaust options?  Probably.  Ugh.  This project is going to be about $36 in sheet metal, and about $999 in welding supplies, haha. 

 

Regarding seat belt mounts, couple options.  Could do the standard thing which is use the eye bolts that come with the schroth harness, through-bolt through the trans tunnel.  But then as you mentioned, there is a bolt end sticking out taking up clearance.  Other options are to weld on a beefy bracket to the trans tunnel and either clip the harness directly to it, or install the eyebolt in the bracket.  Alternatively, use very strong seat brackets, and incorporate an eye bolt in the seat bracket for the harness to clip to.  I rather like that idea, as then if you relocate the seat, the harness mounting geometry remains correct to the harness holes in the seat.  I've read through all of the schroth harness mounting instruction (long document) and see no mention of it being a bad idea to mount directly to the seat brackets.  They are specific about keeping the lap belt as short as possible, and mounting points being no wider than the width of the seat.  Mounting the harness to the seat bracket would accomplish this. 

 

Seat belts are probably the most important thing to anchor well, easily more important than how well the seat is attached.  Would be nice to anchor the all belts to the cage if you can make the belt geometry work.  Better still to mount the seat to the cage too.

 

Tan trim for the win.

[38bfast]

more graphs

[Jim Drago]

more graphs

+1

[speedengineer]

more graphs

 

 

+1

Ha.  Sorry to disappoint.  I was traveling for work all last week, thus no time for the forums and certainly wasn't home to do work on the car. 

 

But, just for you two, a graph: 

 

[speedengineer]

Hille was vandalizing my car.  Says it's not going to be fast!    PS, happy birthday, Justin!

 

 

This beauty came in.  Very well made seat.  I'm not 100% sure about it though.  Pros:  Well made, integrated shoulder reinforcement and nutserts for seat back brace (safety+++), looks awesome, comfortable to sit in.  Negatives:  Too loose around the hips on me, seat bottom cushion too thick, challenging to fit in the car as shell dimensions are quite large.  Pretty sure I can fix the fitment issues as racetech offers a variety of foam pads to customize the fitment. 

 

 

A little video about my new technique to take engine CC measurements using a scale and lab wash bottle.  I'm sure I'm not the first person to do it this way, but I'd never heard of it before, so I wanted to share in case someone finds it useful. 

[38bfast]

We got it to fit in Mikes car very nice. You can do it.

[speedengineer]

Performed an uncertainty analysis on the compression ratio measurement process.  This provides insight into how uncertain the CC process is, and thus how much margin of CR should be left on the table such that the engine will be guaranteed to pass tech/teardown.

 

Stock CR measurement data and uncertainty:

 

 

Predicted CR measurement uncertainty, including uncertainty/accuracy of machinist to shave the head and deck the block.  Not sure yet how much material will be removed from the combustion chambers when cutting the valve reliefs and how far the valves will sink due to valve job.  For now, I just estimated that it's 1.5cc per chamber.  Looks like it would be wise to leave a tenth of a CR on the table, as uncertainty is about a tenth.