825 replies to this topic

[38bfast]

Frank you spend your time at the track working on Kylie's car instead

[Jim Drago]

Like you are going to try your own engine build for $2000. If you can pull it off great but if you fail your out the $2000 + gaskets, fluids, Dyno time, remove and install and the $6000/7000 cost of a probuilt one. Risk you are willing to take. Obviously you feel confident or I don't think you would choose that path. The other issue is will it pass tech. I am very confident you believe it will, but as shown over the past year pro builders messed that up believing that they sent a compliant engine only to be found non compliant. What would seem easy seems no be more difficult than we would have thought.

While not trying to discourage and enjoy reading your posts on this and any new build. I feel it is important to manage expectations as well. The likelihood of producing an engine on V1 that will compete with the likes of the current pro builders is less than 5% IMO. You have to consider what version guys like Stewart,Rossini,Haldeman,Ademir,Tiley and myself are on? I would venture to say all are on V20 plus?

I built my first cars the same way and I think you will meet the budget or real close and will likely build a good car and most importantly enjoy the process and have lots of satisfaction from doing it yourself. I am the only person in SM history to win a national championship in a car that was built completely by me in house, set up by me and driven by me. I consider that my biggest accomplishment in amateur racing, not the driving part. Some of the nicest cars I have seen have been home builds. The last XX is never found on your first build, your first engine etc. My first build was pretty good, but I cheated and bought a pro motor. It is just not that easy even for accomplished mechanical people in a spec class on v1.

[Bench Racer]

Jason, please continue your build up-dates. Many folks are interested including me. 

 

Built my own car (other than roll cage, engine, transmission and Diff) and know the enjoyment/knowledge gained.

 

My V1 has more talent than the spacer between the seat and steering wheel.

[speedengineer]

While not trying to discourage and enjoy reading your posts on this and any new build. I feel it is important to manage expectations as well. The likelihood of producing an engine on V1 that will compete with the likes of the current pro builders is less than 5% IMO. You have to consider what version guys like Stewart,Rossini,Haldeman,Ademir,Tiley and myself are on? I would venture to say all are on V20 plus?

I built my first cars the same way and I think you will meet the budget or real close and will likely build a good car and most importantly enjoy the process and have lots of satisfaction from doing it yourself. I am the only person in SM history to win a national championship in a car that was built completely by me in house, set up by me and driven by me. I consider that my biggest accomplishment in amateur racing, not the driving part. Some of the nicest cars I have seen have been home builds. The last XX is never found on your first build, your first engine etc. My first build was pretty good, but I cheated and bought a pro motor. It is just not that easy even for accomplished mechanical people in a spec class on v1.

 

I agree with you, Jim.  The motor build is the biggest uncertainty in this project, and unfortunately just so happens to be (imo) the most important compenent to running fast laps assuming a competent driver and car setup.  

Unfortunately for me, due to the nature of the buisness, builders aren't likely to share trade secrets.  Despite SM motors being 'spec' there are still lots of design criteria to consider, and I'll have to use my best guess on these for my first engine, and tweak them with future builts.  

Examples:
-Plunge cut both intake and exhaust, or one or the other.  And if so, cut full depth and diameter?  Bottom radius size?
-Piston-to-bore clearance, tight or loose?
-Cylinder bore hone surface finish?
-Need for hot-honing the block?  By my measurements, the cast iron miata block has low mechanical distortion due to bolting the head on, but I'm not sure if it has high thermal distortion or not.
-When maching to achieve desired compression ratio, is it better to deck the block or shave the head?  
-Valve job?  Though I think that's going to be pretty cut and dry considering angles are spec'd.  Also, guessing it's desirable to sink the valves as little as possible.  

There are more considerations too.  I will be deliberating over all of these during the process and make my decsions based on engineering principles, my past engine build experience, and advice from others with first-hand knowledge.  

I'm just going to leave this here again.  Surprised it didn't get any comments the first time I posted it.

[speedengineer]

Jason, please continue your build up-dates. Many folks are interested including me. 

 

Built my own car (other than roll cage, engine, transmission and Diff) and know the enjoyment/knowledge gained.

 

My V1 has more talent than the spacer between the seat and steering wheel.

 Will do!  Thanks!  I don't think I'd enjoy racing as much if it was with a car that I didn't build, I'm sure you're the same way.  It's rewarding to see it all come together.

 

 

Frank - I'm going to keep updating the build here in the forum thread rather than do a blog.  WIth the blog, updates don't show up in the 'view new content' so more people will be able to view and read and contribute if it's kept in the forum. At the end of the build, I'll post a link to the thread on my profile page or a single blog entry so that people can find it if the thread gets buried. 

[MPR22]

As always, I appreciate the advice and tips many have given.  Keep em coming 
 
Just getting going on the build now - been busy getting the house ready for a long winter as well as installing a 2-post lift and getting a new welder set up.  So far, nothing too exciting.  I've been stripping that trunk and interior in preparation for the roll cage build.  Next steps will be to remove all the tar sound deadening and begin scraping seam sealer and removing paint where the cage footings will weld to. 
 

 

 
Unfortunately, the car apparently had a leaky soft top at one point in it's life.  That water caused the rear package tray and fuel tank access panel to be rather rusty.  Looks like I'm going to have to purchase new ones of those. 
 

 
 
On the previous race miata I built, I removed the tar sound deadening using a putty knife and heat gun, then a wire brush on an angle grinder removed the remaining residue.  This actually worked very well and didn't take long, it's just messy.  I've seen dry ice method, but it doesn't appear to come off much easier, and I'll end up dinging up the sheet metal with the hammer.  Does anyone have any other clever tricks for removing this stuff?
 
 
I also scored an OEM hard top for $550.  It does need a bit of work, bit of bondo on the trailing edge where it must have been dropped, and paint of course.  I'll probably have another $75-$125 into it at that point, but ~$650 isn't bad considering how much these go for now days!!!
 

 
 
As everyone has mentioned, difficult to compete at a majors level unless your car is making the HP, period.  I am well aware of this!  It's very possible that my motor build won't make the numbers that the pro builders can achieve, in which case I'll have to pony up some cash and buy one.  However, it's also possible that my motor will be right there.  Anyway, I've run some analysis using a lap simulator I wrote to determine the laptime sensitivity to HP at Mid-Ohio.  Hmm, Mid-Ohio   Anyway, it shows what we already knew, that you've got ZERO chance of running up front if you don't have the motor for it!  Eight hp per second means you can't afford to be down more than a couple from the rest of the drivers, or you will be having to drive all that much harder/better.  I also calculated the laptime weight sensitivity, just for fun. Being lazy setting your fuel load, thus crossing the scales at 20lbs more than you wanted, means you give up about a tenth of a second per lap. 
 

 

Like the graphs, experience says they might be a bit on the high side but may be closer than I think. Think it's closer to three quarter of a tenth per HP. No facts to back up just know that 3 hp is evident on a track 1hp not so much and a .1+ is pretty big gap.

 

 

Edit:  on second thought the 8+ HP per second sounds pretty close though.  At lower HP differences the draft had big impact, when you are 8 HP down you are not able to keep the draft and will have serious time  gaps.  I think 6 HP is good for at least 3/4 of a second at Road Atlanta.  

[FTodaro]

 

 

 

Frank - I'm going to keep updating the build here in the forum thread rather than do a blog.  WIth the blog, updates don't show up in the 'view new content' so more people will be able to view and read and contribute if it's kept in the forum. At the end of the build, I'll post a link to the thread on my profile page or a single blog entry so that people can find it if the thread gets buried. 

You raise a good point.

 

Jim Drago can we get the blog posts to be noted in the new content section on the home page. The blog posts are hidden.

[Jim Drago]

Examples:
-Plunge cut both intake and exhaust, or one or the other.  And if so, cut full depth and diameter?  Bottom radius size?
-Piston-to-bore clearance, tight or loose?
-Cylinder bore hone surface finish?
-Need for hot-honing the block?  By my measurements, the cast iron miata block has low mechanical distortion due to bolting the head on, but I'm not sure if it has high thermal distortion or not.
-When maching to achieve desired compression ratio, is it better to deck the block or shave the head?  
-Valve job?  Though I think that's going to be pretty cut and dry considering angles are spec'd.  Also, guessing it's desirable to sink the valves as little as possible.  

There are more considerations too.  I will be deliberating over all of these during the process and make my decsions based on engineering principles, my past engine build experience, and advice from others with first-hand knowledge.

and that is just your first list... ask three different people and you will likely get three different answers

[davew]

and advice from others with first-hand knowledge. 

 

This could be very dangerous

[speedengineer]

Like the graphs, experience says they might be a bit on the high side but may be closer than I think. Think it's closer to three quarter of a tenth per HP. No facts to back up just know that 3 hp is evident on a track 1hp not so much and a .1+ is pretty big gap.

 

 

Edit:  on second thought the 8+ HP per second sounds pretty close though.  At lower HP differences the draft had big impact, when you are 8 HP down you are not able to keep the draft and will have serious time  gaps.  I think 6 HP is good for at least 3/4 of a second at Road Atlanta.  

 

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:

[dstevens]

 

 

Now, the thing that isn't fair in some ways is that I am not counting my labor cost.  Certainly if you or another shop built the car, you need to get paid for your expertise and ~300 hours you'll have into it.  So yes, it may only cost me $15k to build the car, but if I contracted a shop to build me an identical car, it probably would cost $25k.

 

 

You aren't building a $25k car, though.  For $25k you get a sorted car with a pedigree and setup info to go with it.  You are building a $15k car.  Compared to buying a $10k older car and putting $5k into it having probably just as good, or even better car.  A first time build isnt' going to match a car from Ralph or Drago or or Sean or Meat.  

[dstevens]

Jason I think a resonable expiation for a garage builder would be outsourcing all the fabricating / machine / engine work. Similar to how Frank is building his car. Certainly some people have more resources in their garage but I believe that would be more of an exception than the norm.

I think most hobby racers don't own welders let alone benders (let alone know how to use them).  Many don't own hoists or pullers.   It was that way in circle track as well.  My equipment was paid for well before I even bought the NA rustbucket.  That said, these days I'd get a kit from Sean or Wheeler and spend the day or two and put it in myself.  It's cool to have the software and tools but after you've done them it begins to be more like work.  I basically copied those two and had probably 10 hrs plus in Bendtech before I started cutting and bending with less than a stick in waste.  Now if I were getting paid instead of paying that would be a different deal.  

 

 

I stopped working on cars because unless you do offroad, around here the market is pretty limited and we're able to do much better making DIY 3D printer kits.  Were I to get back into building it it would be offroad.  With the exception of the bender all I have now is used for personal restoration projects.  I'm torn between an early 70s Duster with a 440 hemi (no way could I foot the bill for a Charger or Challenger) or a late 70s F150 restomod with a late model 5.8 Triton.  Just looking for the right donor.  I'm not going to make the bad donor mistake again.      

 

Dave

[speedengineer]

[speedengineer]

Changing gears, I'd like to discuss roll cages.  Specifically, the build procedure.  There are two or three locations where care has to be taken so that you are able to weld 360 around the tubes.  The order that the tubes are installed/build procedure is critical to allow you to accomplish this. 

 

The photos below are of my PTE race car that I built in winter 2013.  Note the red arrows pointing to the following locations:

-Door bars attach to the forward hoop

-Door bars attach to the main hoop

-Eyebrow bar attaches to forward hoops (no red arrow for this one)

 

The general process I used last time was this:

1)  Bend and tack main hoop in place (harness bar and diagonal brace already fully welded)

2)  Bend and tack forward hoops in place

3)  Bend and tack side bars in place

4)  Partially weld side bars to forward hoop, as well as footwell braces

5)  Cut tacks where all side bars and forward hoops attached to the main hoop

6)  Remove "forward hoop and side bar and footwell brace" assembly and fully weld 360

7)  Reinstall side bar assembly, and weld into car and to main hoop

8)  Bend eyebrow bar, install and weld

9)  Cut rear braces and weld to main hoop

This allows you to fully 360 weld the door bars and footwell brace to the forward hoop.  However, it still leaves minimal room to weld the side bars to the main hoop.  Additionally, the eyebrow bar is challenging to weld 360.

 

I'm hoping someone has found a more effective build procedure to use that allows easier welding of the side bars to main hoop, and maybe the eyebrow bar.  It would be nice if the complete assembly of main hoop, forward hoop, and side bars could be tacked up and removed from the car for final welding.  Alas, it doesn't appear that there is sufficient room to pull this from the car in one piece.   The only work-around I have thought of is making the main hoop width about an inch narrower, such that it isn't right up against the sides of the car, and I can get a welding torch in there more easily.  Unfortunately, it'd be nice to have the main hoop be full width.

 

Anyone have any thoughts?

 

 

 

 

[38bfast]

There is going to be way too many options on how to do a cage. I will just keep silent on this one and eat my popcorn.

[dstevens]

Order of assembly depends on the design (and the car but that's a given here) and what works for what I did isn't necessarily the way it will work in all cases.  It's one of those things where fabricator experience comes into play.  I do the main structure and add the bars after that is tacked.  I don't finish weld anything until the entire assembly is tacked unless it's in a place where I won't be able to get to later.  For example the top welds on a car where you can't remove the roof.  A couple of reasons I tack all first, if when I make a mistake it's a few tacks and the part is free.  Heat distortion may also hinder fitting parts if some parts are finish welded prior to final assembly.  The name brand kits have great fits and it just goes together.  One off fits are going to require some give and take.  For that I leave a bit of material on the cope, 1/6" to 1/8" all around the notch.  I can then hand fit to no gap using a die grinder and minimize the root gap on the joint.

[speedengineer]

J~

 

 

I did the dry ice method Thursday night!  It was pretty effective.  It still took a while, but I think it was faster than the heat gun and putty knife method.  Definitely cooler, both figuratively and literally.    It'll still require going back with a wire wheel/pad to prep the surface prior to paint.

 

Couple thoughts/tips:

 

1) I used plain dry ice on the driver's side and the dry ice and isopropyl achohol mixture on the passenger side.  While it was marginally faster with the alcohol (faster heat transfer from the sound deadening due to better contact) it was rather messy, soaked your gloves, and smelled awful.  Garage smelled for two full days.  I wouldn't use the alcohol again.

 

2)  I found using dry ice on the vertical panels to be challenging at first.  It's difficult to hold try dry ice up against the panel with either a large trowel or thick gloves.  By the end I figured out a trick though - put your finely crushed dry ice in a plastic grocery bag, and then press the bag up against the surface.  The bag is so thin that it doesn't impede heat transfer, but it prevents the ice from falling out.  Way easier.  In fact, if I did it again, I'd even do the horizontal sound deadening with the bag method.  Otherwise when you start breaking up the sound deadening, the chunks get mixed in with your dry ice.  Also, when the ice is out of the bag, it makes so much fog that you can't see what you're doing and if you missed any spots.

 

I bought 18 lbs as one brick at 9 lbs didn't look like enough.  I had a lot extra, 12 lbs would probably have been about perfect.  That said, make sure you can get extra so you can make a dry ice bomb afterwards.    I'd never made one of those before, and holy crap it was loud.  2-liter pop bottle.  Make sure you're nowhere near it when it goes off...

[Keith Andrews]

 

That said, make sure you can get extra so you can make a dry ice bomb afterwards.    I'd never made one of those before, and holy crap it was loud.  2-liter pop bottle.  Make sure you're nowhere near it when it goes off...

 

Come on now, if you are blowing stuff up video is required.

[speedengineer]

Come on now, if you are blowing stuff up video is required.

 

Next time!  It was pitch black outside.  It was so loud though.  Reverberated off the surrounding hillsides for a solid 6-7 seconds haha

[High Chair]

It's good to see we are back talking about SM's. Good luck with your car!!!