Announcement

Collapse
No announcement yet.

Updating a GA16DE powered B13 hillclimb car

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • RallyBob
    replied
    So, on to the fender clearance issues. Friday afternoon I drove to Tim's house and started on the rear fender rework. The biggest contact issue with the B13 chassis is at the rear of the wheelwell opening. It has to do with the suspension geometry pushing the wheel backwards in the wheelwell as it travels upwards.


    Here I take my Kett shears to the steel flares I made previously. Oh well, easy come, easy go!



    At this point, I've already cut the outer fender nearly flush with the top of the stock wheelwell. The inner section that normally meets the outer fender was cut out entirely, and a new mini-tub about 4" wide was made. This was then welded to the outer fender at the cut line.



    Here you can see the fender cutout is basically flush with the top of the wheelwell. Tim slapped on a coat of POR-15 then covered that with Rustoleum yellow. Seams are seam-sealed to keep water and dirt out too.



    Before the flare goes on, you can see that the amount of droop he has compared to the Koni's is amazing!



    The car is definitely "jumpable" as it sits now!



    Down on the ground at regular ride height, with the rear flare riveted in place.

    Mount Washington is happening in just two weeks, wish Tim luck up the hill!

    Leave a comment:


  • RallyBob
    replied
    So, the second hillclimb of the season for my friend Tim has come and gone, namely Mt. Okemo. The new Bilsteins were fitted for this event.

    Sadly, there was no time to wait for zinc plating of the strut bodies and the top mounts, so a thin coat of paint was shot onto these parts that might otherwise oxidize rapidly. There were a few fitment issues like brake hoses up front that were too short and rear camber issues, but otherwise everything fit up pretty well.

    As far as the performance of the struts, Tim said he didn't notice anything good or bad about them. However when other drivers approached and asked about how he was hitting a huge frost heave and other bumps without upsetting the car, Tim just said "what frost heave?". So yea, they pretty much soaked up whatever he threw at them.

    The biggest issue by far was the lack of negative camber in the rear (since remedied), and the rubbing of the rear tires in the fenders. This was partially due to the lack of camber, and also due the greater suspension articulation and travel.

    This weekend, I cut off the steel fender flares I made in 2014, and mini-tubbed the rear wheelwells. Tim then fitted some generic rivet-on urethane flares, which were wider and taller and allow for unimpeded wheel travel.


    Rear top mounts and spring hardware



    Front camber plates.





    Struts fully assembled, ready for pressurizing to 200 psi with nitrogen, and ready for 275 lb front springs and 225 lb rear springs with flat wire helper springs.


    Rear strut installed with springs.


    The car has has a bit more body roll perhaps but it has grip and is easy to drive fast. Soaks up high speed bumps with ease. This is at Mt. Okemo a week ago.

    Leave a comment:


  • induetime
    replied
    Love the Duel Plenum Intake & all of the custom fabrication! Great project.

    Leave a comment:


  • 2_Liter_Turbo
    replied
    That's a fantastic picture! Ha ha

    Leave a comment:


  • RallyBob
    replied
    This was Tim just yesterday, shaking the car down at the spring Mt. Ascutney Hillclimb in Vermont. As you can see he cut the corner a bit tight, and launched the car onto two wheels!

    He's always trying to break stuff I build.....


    Leave a comment:


  • RallyBob
    replied
    Updating this old thread rather than starting a new one. My friend Tim hasn't done any racing since 2014, but he is entered in the 2017 Mt. Washington Hillclimb again.

    I haven't done any fabricating or car stuff since fall of 2015. I closed my shop down and put everything into storage, bought a new house in another state, and have yet to build a new workshop there.

    Tim was hoping to improve his car a bit more for this year, so two things were done. One, he fitted a Megasquirt Plug'n'play ECU and eliminated the MAF sensor. This was not without its share of issues, and the Megasquirt was sent back and forth 3 times for problems, and we abandoned one dyno session too as a result. Anyway, his 17 year old engine made 6 less HP than when it was new, but it made 12 more ft lbs of torque than when it was new. RPM range was entended as well. Better, but not as good as a turbo. That new turbo engine will have to wait until I have a new shop....

    The second big change will be changing from Nissan B15 Koni sport inserts, to 46 mm Bilstein universal motorsport struts. Keeping in mind this is not a slammed to the weeds road racer, and does mostly rough New England hillclimbs, I went with the longest travel struts I could fit. We chose 7.8" travel front, and 8.8" travel rear inserts.

    The front of the car has raised strut towers (1.5" higher), and I found I could lower the strut body relative to the mounting flanges a bit, and retain lots of travel in both directions at a slightly lower ride height than stock.

    In the rear, since there's no halfshaft in the way, I can just lower the strut body a bunch relative to the mounting flanges and retain good compression and droop travel. More travel on rough roads = more grip.

    The top pins were machined down to .750" for use with common 3/4" monoballs, and they were tapped for shrader valves as well.

    I made some 1/4" thick chromoly camber plates to replace the old aluminum ones Tim had on the car (now bent up after years of rally use). The monoballs were 5/8" previously.

    For the rear strut top mounts, I used the upper portion of the stock rear mounts. I removed the rubber bushings, enlarged the hole at the top, welded in a monoball housings and welded in bolts for mounting studs. With the low profile Bilstein spring hats, I have more room vertically than the OEM setup.

    Unfortunately I ran out of steel while mocking up the strut flanges, and have to wait for more material. That, plus the 110 mile drive to where my welder is being stored (at a friend's race shop) means it'll be a week or two before I get back to work on these. But the top mounts are ready for zinc plating at least.











    Leave a comment:


  • RallyBob
    replied
    Originally posted by jfryjfry View Post
    Curious about your tire size.... I run 255's on 9" wide wheels and they look to fit about the same as yours - I expected to see some stretch to fit the 225's but they look pretty square.

    I guess no real question... Just interesting. Very nice car!
    Hoosiers do tend to run wider than other brands. They list an 8.6" tread and 9.3" sidewall for this size.

    Leave a comment:


  • RallyBob
    replied
    Originally posted by Def View Post
    Nice fab work!

    As far as ditching the aluminum exhaust on a turbo engine - you should keep it. The post turbine exhaust temps will be LOWER than on pretty much any NA engine. The turbine takes out a ton of heat energy (200-400 deg F easy), so the turbine housing goes from glowing to well below 800 F right at the turbo outlet.

    I'd use a short section of stainless out of the turbo, but once you're past the oil pan I'd keep the aluminum exhaust (unless the diameter is too small - you want a 3" exhaust really). A 2.5" exhaust that's free flowing might be enough, but for a race car ya might as well go 3" if you can fit it.
    The aluminum is only 2.5". I was planning on 3" stainless tubing for the turbo engine.

    Leave a comment:


  • jfryjfry
    replied
    Curious about your tire size.... I run 255's on 9" wide wheels and they look to fit about the same as yours - I expected to see some stretch to fit the 225's but they look pretty square.

    I guess no real question... Just interesting. Very nice car!

    Leave a comment:


  • Def
    replied
    Nice fab work!

    As far as ditching the aluminum exhaust on a turbo engine - you should keep it. The post turbine exhaust temps will be LOWER than on pretty much any NA engine. The turbine takes out a ton of heat energy (200-400 deg F easy), so the turbine housing goes from glowing to well below 800 F right at the turbo outlet.

    I'd use a short section of stainless out of the turbo, but once you're past the oil pan I'd keep the aluminum exhaust (unless the diameter is too small - you want a 3" exhaust really). A 2.5" exhaust that's free flowing might be enough, but for a race car ya might as well go 3" if you can fit it.

    Leave a comment:


  • 2_Liter_Turbo
    replied
    Nice work!

    Leave a comment:


  • RallyBob
    replied
    So here are a few of the mods I did last spring, prior to the 2014 hillclimb season. Previously the car ran 205/50-15 tires on 15 x 7 wheels. We had a set of 15 x 9 949 Racing wheels from the other (SE-R) project car, and decided to try to fit them to the Sentra SE. The front wasn't much of an issue as the car owner Tim had spaced the bottom of the front fenders out which gave adequate outer clearance. A little bit of wheel spacer shuffling and all was well.

    Out in back, there was trouble in both directions. The outer fenders rubbed with the old wheels and tires, and when we removed the wheels spacers to test fit the 9" wheels they rubbed something fierce on the strut bodies. So I did two things: I made new rear strut housings from scratch (from aluminum), and made longer mounting flanges to push the strut housings more inward. That helped with inner clearance. But outward clearance was nil, even with hammered inner fenders. So I decided to make some fender flares from sheetmetal, and cut and rewelded the inner fenders to match. This gave the clearance required for the new 15 x 9 wheels and the 225/45-15 Hoosier A6's we planned to run.

    Laying out the 22 gauge steel fender flares from my cardboard template.


    I stretched and shaped the flares using a plastic teardrop shaped hammer and a shotbag, followed by a few passes through an english wheel to smooth the hammer marks out.


    I roughed out the flare's outer edge on a t-dolly.


    I made this special job-specific radiused t-dolly in order to make a more refined outer edge.


    Tightening up the radiused edge.


    For even more edge strength and no sharp edges, I hammered the outer lip over further.


    Here the flares are fully trimmed and metal finished, ready to go onto the car.


    Cutting out the stock outer fenders.


    Hammering the inner fender out for more clearance.


    Tack welding the new flare into place. I used all TIG welding. It's slower, but it's far more controlled and has a smaller HAZ (heat affected zone) than MIG welding. Plus the weld itself is much softer and smaller, which means it's less prone to crack and far easier to sand down. I used .030" ER-70S6 filler rod to weld it.


    Here you can see I jump around the flare edge welding little 1/2" to 3/4" long beads to avoid warpage.


    Fully welded.


    Fully sanded down to 220 grit.


    As you can see, that's a lot of tire on a Sentra!




    Here's the custom grooving I gave the Hoosiers for Mt. Washington. The road goes from pavement to dirt and back to pavement so tire choice is always tricky. I selected this pattern after years of prepping tires for that particular hill. I leave the outer shoulder slick since I figure on asphalt there will be more grip therefore the car will roll over the tires onto the outer edges. But on dirt, there is very little lateral grip so the tires stay on the inner edges due to the negative camber we run. As it turns out, the car is very fast, very forgiving, and the tires wear dead evenly across the tread. So it seems to work well.


    One of the things I did for last year's event was make an all aluminum header-back exhaust. We managed to save 30 lbs over the old steel exhaust with two mufflers. We won't be using this sytem for the turbo engine, that will get an all stainless side-dump exhaust system. Aluminum would melt on a turbo engine!


    Here's Tim near the summit of the hill, right at 6000 ft. I figure at this point the car is making somewhere near 75-80 hp thanks to the altitude. Ouch.


    Here's the car at 'cragway'. Tight righthand uphill corner on dirt. You don't want to go off on your left....




    Another random pic on the mountain:

    Leave a comment:


  • RallyBob
    replied
    Originally posted by Def View Post
    BTW - how did you plate the vacuum rail. At a plater or a DIY home job?
    Paid a shop to plate them with yellow zinc. I looked at the DIY kits but I'd have needed a fairly large kit due to the rail lengths. It was ultimately cheaper.

    As far as the suspension goes, I added tender springs last year for more droop without dropping the main springs off their perches. Seems to have worked better. I also added monoballs to the lower links on the rear uprights. That made a huge compliancy difference so when I go full custom I will have zero rubber or poly out back.

    Leave a comment:


  • Def
    replied
    BTW - how did you plate the vacuum rail. At a plater or a DIY home job?

    Leave a comment:


  • Def
    replied
    That hill climb was awesome. So much WOT...

    I can imagine with a surface like that it'd be better to have quite a bit more travel and softer rates than a track car. The car was losing traction on power very regularly. Maybe a dual spring setup to get even more travel with long stroke struts at a slightly higher ride height so that you can have a firmer rate when cornering, but you've got a ton of droop with a lighter spring rate once the tender becomes unblocked.

    Leave a comment:

Working...
X