200sx SE V6 Endurance Race Car Build

[Max]

Huge apologies for not keeping up with this.  The race car has been finished.  Please ask if you want to know anything specific about the build.  I know the thread is not current, but I can comment and add pictures on any area of the car... just ask!

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Epic update:

I know its been a while since the last update.  Basically for the last three months I've been worrying myself sick trying to prepare the car for PIR, and studying for the PE exam (9.5 hours long) which is the day before we tow the car to the track for tech.  Impeccable timing!

The car's first race was last weekend at Portland International Raceway with LDRL 8+7 with 45 min. night sprint.  This is where it all started for Chumpcar back at the 24 hour race on Halloween 11 years ago.  That is also where I got hooked, volunteering from pit lane.   Only 11 years later, I'm returning in my own car. 

Three team mates put their faith in me and signed up enthusiastically to drive.  Funny thing is, the original team all dropped out at various times for various reasons.  This team came together in the last month before the race.  Two former team owners (rx7 & e30), and one friend that I attended UTI with 12 years ago who's never driven on a road course.  Basically, I was worrying myself sick that the car I'd spent two years preparing to race would break on these drivers that gambled on me and the new car.

Strategy was pretty simple for Saturday's 8 hour enduro, as I knew the odds of things going as planned were slim to none. I wanted to get all my drivers seat time before I got in the car. Just in case there was any incidents that kept us off track, I didn't want them to miss out. I asked them to stay out as long as possible, basically until the car started to stumble from low fuel.  I was pretty sure that with a 14 gallon tank, the car would only go about 1 hour 40 minutes. So with any luck we could get it done in 5 stints. 

 Qualifying:
I put my friend who'd never driven a race car before in for qualifying, to hopefully work out some novice jitters.  This worked! One spin by himself in the chicane, but otherwise trouble free.  

Start:
For the start of the race I put our most experience driver in, who had campaigned an FC rx7 for about 8 years.  He kept us out of trouble for the start, and started to get comfortable in the car he'd never driven before.  Everything went to plan, but then it started to mist pretty heavily.  About 30 minutes into the race and we see him coming down pit lane.  He informs us he had a huge spin in turn 11, which is a darn fast corner.  Luckily, after spinning a few 360's, he came to a stop without hitting anything. He pulled right into the pits and said he thinks something is wrong on the back end of the car. We checked it out and couldn't find anything, sent him back out and told him to take it slow.  Ok, first unscheduled pit stop, but hey we know we're not going to win today. About 1:35 into the race, he comes in for the end of his stint. Fast lap 1:46.1, half stint was in the wet.


First fuel & driver change:
Got our 1st driver out of the car, and I started fueling.  Holy crap it's taking fuel slow.  I need to modify my filler neck to make these hunsakers dump faster.  Car took just over 10 gallons, not good in a 14 gal tank.  Driver reported about 6 laps of sputtering in the tight right hand corners.  Put our next driver in, the rookie.  Also went from our biggest driver to our smallest driver, and this was challenging with a fixed mounted seat.  I need to relocate my lap belt mounting point on the door side, as it was dang near impossible to tighten without hurting yourself. 


Second stint:
Uneventful!!! My buddy who had never driven a race car stayed out of trouble, kept it on track, and brought it home for the next driver.  No rain thankfully. He lasted an hour and fifty minutes before sputtering, was not as fast as the first driver but was able to do some laps in the 1:46's.  Learning how to go fast can come later, I think he learned a lot about managing traffic and driving predictably.  Two criticism's I have are that he left the popups up the whole time, and put the steering wheel on crooked.  The ONLY video that worked all day was 50 minutes of this stint. I guess it's good that we got video for the new guy!
 

https://www.youtube.com/watch?v=zPNAfm0JLGk

Second fuel & driver change:

Same deal but smoother than before.  I put another 10 gallons in or so.  3rd driver is in (former e30 team owner), and off. 
 

Third Stint:
This stint was going smooth, and our lap times started to come down.  The track was still dry, and she was able to set a few times in the 1:45's.  After about 15 minutes the driver comes in for an unscheduled pit, and said the rear brakes are howling.  I asked if the brakes are still working, and she said yes.  I explained I think this is just the pads.  I don't know why they're howling but I suspect that there's too much rear bias, and the rear brakes are working too hard and getting too hot.  I used hawk blue front and rear, and I'm kind of thinking I should have staggered compounds and run a less aggressive pad like HP+ or HPS in the rear.  I told her to go back out and be careful in the braking zones if she felt comfortable.  She said she's having fun and wants to keep going. Alright!  Hour and a half total stint time and she comes in saying it just started to sputter. 

 

Third fuel & driver change:

O

M

G 

The car made it this far, every driver has had a full stint.  I can get in the car worry free now, just icing on the cake from here on out.  The stress is melted away and it's time to really enjoy the fruit of all this. No idea how fueling went, this was all a blur. 

 Fourth Stint:
I've been waiting for this moment for my entire life!!!!  In July I did a track night and was able to do a 1:41.8 on some older RS4's.  I have new one's today, and improved some bushings, new clutch, and cut the rear springs more, so hopefully I can be faster.  Basically we started from the back of the pack at the beginning of the day (50 cars or so total) after our spin & unscheduled pit stop.  Every driver moved us up a couple of spots and we were sitting somewhere around 26th overall by the time I got in.  I start getting settled in to the car, and lap times start dropping.  The body roll is still horrendous, but if you're patient with the weight transfer the car actually has some good mechanical grip. Pretty soon I'm beating my times in the 1:41's, 1:40's, and then a 139.9 and our fastest lap of the race.  I keep this up for a while but keep getting caught up in full course yellows, including one for an e46 that went into the wall right in front of me.  For some reason the car doesn't seem very fast to me despite burning off fuel weight, and running the engine up around redline causes a feeling of power surging.  Pretty soon I started to see my tachometer wigging out and flickering, and I'm suspecting an ignition problem, like a plug wire or something coming loose.  It seems like randomly the engine is down a cylinder.  About an hour twenty in to my stint, another full course yellow.  I putt around in 5th trying to save fuel as it basically reads empty, but no sputtering yet.  Green flag drops and I'm battling to keep some cars behind me, one specifically that I know is in my class. I actually want to race even though I might be battling for a position in the teens. Things went well for half a lap until we get to the hairpin, turn 7, which leads to the back straight.  I manage to stay ahead of about 3 cars setting up for turn 7, point the car and lay into the throttle...  All three of the cars fly by me on either side like I'm not moving.  I pump the throttle and just hear a really loud rattle.  Wot only results in me maintaining speed, but almost no accel.  I limp to the pits and inform the team that we lost the engine, suspected spun rod bearing.  Turned the car off and we pushed it into the cold pits.  After that, we tried to restart the car and it wouldn't fire.  Ultimately, I spent an hour testing to find out that the electrical problem I was experiencing was a battery cable crimp that was coming loose at the battery under the shrink wrap. Found out my battery mount was inadequate, and probably stressed that crimp until it failed.  Fixed that, fired the car while we were all listening... pretty obvious rod knock.

Our race is over.  We loaded it on the trailer and loaded up our pits. Missed out on the night sprint, and the Sunday 7 hour enduro.  Honestly the whole week was a rollercoaster and highly stressful, and I left the track feeling really incredible about how it all turned out.  The team seemed to be in good spirits despite losing out on the rest of the weekend, but there was also some relief that the new car was a blast and we all drove a lot.  We were also freezing our butts off, so that could have contributed!

 I also got a lot of love from the organization and other racers. Many compliments on the new build.  Some even called it "clean" but I would say they must not have looked very close.  Overall a really positive race weekend with a great group of racers. 

Takeaways: 

Obviously I need a new motor.  Picking up a vg33e core on Thursday to rebuild over the winter.
Need stiffer springs bad.  I think my cut springs are probably around 200 lb/in.  Will probably shoot for 350F300R.
Hydramat or surge tank.  We need to use more than 10 gallons of our 14 gallon tank. No money/time for a cell.
​Radios.  They would just be really handy.
Video.  Would like more than 50 minutes of working video.
Diff.  Currently open, if budget allows I'll get an LSD.  If I'm feeling really brave & broke I'll weld my diff. 

I just can't wait to get back out there.  Thinking about doing both PIR events next year. 

[CzechSilvia]

Great read! Get it fixed fast so you can humiliate some drivers in the newer cars

[Max]

Thank you! I will do my best.  There are 2 races a year at my home track, and that's probably the only one I'll do for the next couple seasons.  Those are in June or July, and October. 

I think we'll need to drop about average 3 sec/lap to be in contention for podiums. Better springs will get us close to that, and if I can get an LSD or locked diff I think we could be there.  I will be rebuilding a vg33e for the car, and probably adding some mild camshafts which should help to a lesser extent.  When we're 3 sec/lap faster, and can use almost all the fuel in our tank, and we don't screw anything up majorly, we'll be competitive!

[kelso840]

Way to go out there and represent our chassis!

Are there any aftermarket parts you can use in the rebuild to help the engine survive a whole race?

[Max]

Way to go out there and represent our chassis!

Are there any aftermarket parts you can use in the rebuild to help the engine survive a whole race?

That's a good question. 

Long answer: First off I think that a lower mileage vg33e from a 2003ish truck is going to be more reliable.  They have revised oil pumps, and mine was an oil related failure.  Also, the engine I blew up had an odometer stop at 242,000 miles and was apparently on it's original motor.  So just by putting new rings and bearings in the vg33e should make for a much more reliable engine.  I have considered modifying the oil pan to hold more oil, and add trap doors to try and keep the pickup always in-oil.  A lot of cars do this kind of racing and don't have regular rod bearing failures with stock engines, so I would like to believe it can be done without going with an accusump or anything like that.

I do intend to put in some cam regrinds to increase the power a bit, which isn't going to help the reliability at all.  I have no intention of raising the RPM range of the engine, as high RPM is a direct effect on engine durability.

Short answer: Newer engine with new bearings, maybe upgrade oil pans.

Photographer is finishing pictures from the event...

[CzechSilvia]

Whatabout an oil cooler, are you running one? I'd definitely run one in an endurance race car.

And since you have to put a new engine in there, you could diy the extended oil pan, the new engine would already be out of a car so it would be a lot easier. I don't think that would be too expensive and the vg33 would like that for sure.

As for the lsd, I have a Quaife torsen type diff in mine which I  love and I think it would be absolutely perfect for your application. It's a world of difference, I can put the power down a lot earlier coming out of a corner and my ca18et probably has half the torque of that v6 of yours, I think it would blow your mind what a difference can lsd make to your car on a track. Although it's hands down the most expensive aftermarket part on my s12, it was worth it, the car's a lot faster, I'd go for a torsen type lsd if I were you, it takes regular gear oil, you don't have to mess with any friction plates and setting it up, it just works and it's virtually indestructible which is probably a plus in endurance racing.

Also I don't know what shocks you have on the car but if you have some worn oem ones there, I'd be really careful with just slapping some stiffer springs on the car and calling it a day. The soft factory shocks seemed pretty useless to me to begin with and I don't think they could perform well or last long paired with stiffer springs

[Max]

Whatabout an oil cooler, are you running one? I'd definitely run one in an endurance race car.

And since you have to put a new engine in there, you could diy the extended oil pan, the new engine would already be out of a car so it would be a lot easier. I don't think that would be too expensive and the vg33 would like that for sure.

As for the lsd, I have a Quaife torsen type diff in mine which I  love and I think it would be absolutely perfect for your application. It's a world of difference, I can put the power down a lot earlier coming out of a corner and my ca18et probably has half the torque of that v6 of yours, I think it would blow your mind what a difference can lsd make to your car on a track. Although it's hands down the most expensive aftermarket part on my s12, it was worth it, the car's a lot faster, I'd go for a torsen type lsd if I were you, it takes regular gear oil, you don't have to mess with any friction plates and setting it up, it just works and it's virtually indestructible which is probably a plus in endurance racing.

Also I don't know what shocks you have on the car but if you have some worn oem ones there, I'd be really careful with just slapping some stiffer springs on the car and calling it a day. The soft factory shocks seemed pretty useless to me to begin with and I don't think they could perform well or last long paired with stiffer springs

Lots of good points here.

You're right about the oil cooler, that should definitely be on the list! I wish I had an oil temp gauge to see what kind of temps the oil reached. That would tell me if the oil temps were a contributor to the rod bearing failure. I do have a coolant temp gauge, and the coolant even with the stock radiator stayed right around 170 for the entire race. Larger oil capacity could help a lot with oil temp fluctuations as well. This engine does not have a very high oil capacity.  The truck oil pan has a bump out, and I might try and mimic that to add another quart or two of capacity with hinged trap doors.

You have a quaife, that's awesome! If money weren't an object, I would buy that diff too.  In my experience racing a miata, the torsen diff is everything I could ever ask for in a differential.  My boss who runs spec miata, has used clutch type diffs (mazda comp I believe) in endurance racing and they simply do not withstand the hours and hours of abuse.  He blew up two of them in one weekend endurance racing.  You're right, I think torsen is the best option for endurance racing.  There is another s12 team out here, believe it or not, with an LS2. They told me they use a OBX quaife knock off diff and absolutely love it, and have had no failures.  I would consider that too.  Yet another S12 team with a BMW engine swap use a weir spool (locked) diff. I'd prefer not to go full locked diff, but they are faster and about 80% as good as using an LSD.  If I can get my team on board to drive with a locked diff, I may go that route. I know there's bad, good and best options and there's a cost associated with each.  Right now I'm using "bad" and it's costing lap times.  I can tell you I will not be able to afford a quaife before the next race, but I will try to address this somehow.  You're right about putting the power down in corner exit.  Right now I have to coast through the first part of the chicane, and the other hairpin I have to bog through in 3rd gear or it will completely roast the inside tire.  I believe I'm loosing at least a second if not 2 per lap with the open diff.

Shocks are brand new GR2's.  I don't want to overload them, so I'm not going to go too crazy on spring rates.  I'll test it at a track day before the race weekend.  AGX's are an option, but again another cost.  We'll see if they hold up. 

I appreciate your input!

[Max]

Been a while, but I'm steadily making progress on this build.  The Vg33e is rebuilt and I just dropped it in the car.  The 3.3 was very worn out, had to be bored .5mm over and Isky said the cams were in too bad of shape to regrind.  So this engine will use stock s12 cams.  Believe it or not the oil pan mods probably took me longer than the rebuild.

https://www.youtube.com/watch?v=DEEw-SY4SCU

[iceageg]

The stock S12 VG30 cams should actually be a little bit taller/better and allow the VG33 to breath more so that's probably the way you wanted to go anyway if you were not doing some custom grind on them.  If memory serves the Z31 turbo cams are the "best" stock cams you can find that will swap directly in.

[Max]

Right, the truck cams are pretty puny compared to the car cams.  They have lower lift and lower duration, and as a result the peak power is ridiculously low in the rev range.  IIRC it's something like 4900 rpm.   The engine felt like it wasn't pulling anymore after about 53-5400 rpm, and I wanted some isky regrinds to raise that peak power up closer to 6000.  That plan fell through and with the tight budget I just ended up using the s12 cams for a milder upgrade.  Hoping the power comes up in the rev range due to the better flowing heads and the mild porting I did.  Maybe I'll do cams next year if nothing else major needs to be repaired over the winter.

[Max]

Sorry for the lack of updates... it's not due to lack of progress.  However, in the time since the last post I have done a lot of worrying and tracking down little stupid problems.

When I got the engine all buttoned up, I could not get oil pressure while cranking... Even when I pulled the oil pressure sending unit, oil would not flow out.  Unfortunately, this is the first oil pump I've ever replaced with a brand new unit.  I've never needed to replace one before, and I replaced this one out of guilt for how much I'd already invested in the engine. There was some wear on the drive surface that touches the crank... so I replaced it.  Unfortunately, I didn't realize how hard it would be to build oil pressure.  Eventually I pulled the oil filter housing, and put a funnel into the discharge port on the pump, filled with oil, rotated engine backwards gently to ensure oil was pumped into the pump and down into the pan.  This worked.  After about 45 straight seconds of cranking with no spark plugs, the gauge flickered.  WHAT A NIGHTMARE!! All the surfaces had some very sticky/thick assembly lube, and hopefully all my worries are for nothing.

Will report more later.  For now... First drive!

https://www.youtube.com/watch?v=2cr-Vf3UFRg

[sideways_s12]

 Nice glad to see the updates. Shitty you're having issues. I love the stance on your I may have missed it but whats the suspension set up your running and also what are you using to post pictures?

[Max]

Nice glad to see the updates. Shitty you're having issues. I love the stance on your I may have missed it but whats the suspension set up your running and also what are you using to post pictures?

Thanks for the feedback! And the issues are inevitable, but it's starting to feel like I have the major ones behind me now that it's drivable!

As with a lot of these budget series (Lucky Dog Racing, Champcar, 24 hours of Lemons) it's pretty common for some garage engineered suspension setups. Some series even penalize you for running aftermarket components.  LDR is not that way, but I'm still limited by budget.  I replaced all the shocks/struts with short stroke GR2's from a MR2(front) and fox body (rear), and so far they've been fine but when I upgrade springs I'm not sure if they'll hold up... we'll see! Springs are cut SE V6 springs, about 1.5 coils in the front and 2 coils in the rear, which made the ride height about even.  Although this works, and was fine for street driving, when you put sticky rubber on and hit the track the flaws become very apparent.  The front springs have fewer active coils and increase in spring rate much more dramatically when cutting than the rears do... So the front is stiff and the rear is still really soft... As you can see in one of the pictures I'm lifting the inside rear tire going into the chicane at PIR.

One of the highest priority mods for this car over the winter (other than the engine) was to bump up the spring rates significantly. I think this change alone will be worth seconds/lap. For that I have purchased some coilover sleeve parts and some 6kg/mm (340ish lbs/in), and camber plates for the front.  The rear I found some eibach springs on a z31 in the junkyard (215 lbs/in).  They fit right in, but raised the car back to stock height.  I cut 3.5 coils off of them and they're just about right... they should be much stiffer.

Stock spring next to z31 eibach


After cutting (thank God all of the "soft" spring rate coils are gone, so they're no longer progressive


As far as camber goes. The rear increases in camber as you get lower, so I didn't have to mod anything there... and I was able to get the toe close to zero.  The front I drilled new holes for the lower control arm mount farther out about 10mm and up about 10mm to get the suspension geometry closer to normal while increasing camber.  The tire wear showed that this wasn't quite enough camber because my outside shoulders are still getting really hot. The coils and camber plates will help this.

For image hosting I've been using imgur.com.

[Max]

Quick update:

Drove the car to work.  I have such little free time, married with 3 kids, that often my best opportunity to test the car is by commuting it to work.  My job is 30 miles away. After breaking in the new engine for about 25 miles at variable RPM and a few good beatings, I believe it's ready to make the trip up the freeway. I always joke with my wife when I drive the racecar to work that I hope she doesn't have to come get me.

Well the car did great.  It almost feels like the engine is gaining power as I break it in.  The thing pulls hard! I need an LSD now more than ever 

Until it wasn't great.  On the way home the tach started dropping sporadically, and then the car started to sputter, eventually shooting fireballs and popping like crazy.  Eventually there wasn't enough power to keep the car moving.  Pulled over on a busy street.  Tried everything while I was sketchily parked on the shoulder but couldn't make sense of it.  The car seems to have no spark, and I literally just went through this when I was finishing up the rebuild.  I replaced the coil before and haven't had a problem since.  My first thought is that the coil is bad again.  Since I have no time, I ordered another one, and if it fixes the car I'll work on getting the old one warrantied.  Then I'll have a spare, and I can try to figure out if my car is actually killing coils or I just got a bad one.

The joke about my wife coming to get me turned real, and nobody was laughing that night  All is well now, and my trusty tow rig did excellent 



Coil gets here today...we'll see if I was right.

[kelso840]

Your car even looks good being towed behind a minivan.

You've got a VG33E, right? I know the s12 is significantly lighter but it's funny to think about that motor being enjoyable. It's totally gutless in a Frontier.

AAA auto insurance with free towing (up to like 10 miles) has bailed me out a few times. They get a little weird about taking your car back to a house since you're supposed to be having it towed to a shop for repair, but it can be done.

The joys of driving old cars!

[Max]

Your car even looks good being towed behind a minivan.

You've got a VG33E, right? I know the s12 is significantly lighter but it's funny to think about that motor being enjoyable. It's totally gutless in a Frontier.

AAA auto insurance with free towing (up to like 10 miles) has bailed me out a few times. They get a little weird about taking your car back to a house since you're supposed to be having it towed to a shop for repair, but it can be done.

The joys of driving old cars!

Thanks Man!

I hear yah... The frontier/pathfinder/xterra is SOOOO slow with these engines.  But my car is probably 2000 lbs lighter than those vehicles, so it does alright!

I've thought about AAA, and might look in to it.  Wife and I are also discussing buying a tow dolly for times like these, and to tow to the race track.  We can't afford a dedicated tow vehicle at the moment, so we're always towing with whatever she's driving. That's the quest right now with only a 3500 lb rating. Not enough for a flat bed + 2500 lb race car.

[iceageg]

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I hear yah... The frontier/pathfinder/xterra is SOOOO slow with these engines.  But my car is probably 2000 lbs lighter than those vehicles, so it does alright!
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Also, you got to swap out cams optimize the platform.  Along those lines, a friend of min who is running a VG30/33 hybrid in his hardbody found two pulley's to weld together that maintained belt alignment while still using the VG33 water pump (higher flow) instead of a notched VG30 pump.  He sent a picture but I need more details about what pulleys he used before I post the info.

[Max]

Also, you got to swap out cams optimize the platform.  Along those lines, a friend of min who is running a VG30/33 hybrid in his hardbody found two pulley's to weld together that maintained belt alignment while still using the VG33 water pump (higher flow) instead of a notched VG30 pump.  He sent a picture but I need more details about what pulleys he used before I post the info.

Agreed, I can't imagine what the power band in the car with the old truck cams would feel like.  Maybe fun for autocross, but not road or drag racing. I kept the s12 cams.

I'm assuming you're talking about keeping the 30e crank and using the 33e water pump?  I used all of the 33e stuff, crank, water pump, alternator, etc. Unfortunately with the stock bracket the PS runs right into the frame rail... so I have to make something to get that to work.
Post Merge
Also.  New coil didn't fix the car. Might swing by the junkyard on my way home and look for a spare PWR-2 power transistor.  The car still has a code 21 ignition signal.  If/when I come across some free time I'm going to run through the diag procedure in the FSM for that code.

[kelso840]

Could it be a crank position sensor?

[Max]

Could it be a crank position sensor?

Off the top of my head I believe that would be a separate code, not code 21.  Also, I've turned the motor over by hand and heard the individual injector clicks as the engine turns.  So my thought would be to rule that out... It's a potential cause for sure, but I'm not leaning that way just yet.