520R SV build has commenced

[JohnCh]

I picked up the car from the dyno this afternoon.  It was a day later than expected, and as a result, my alignment appointment has been bumped to Monday.  The dyno shop was very, very good.  They went over the car in great detail, took pictures of everything they found (lots of little oil leaks that I missed), and kept great notes both on my expectations/instructions and their findings during the inspection.  Attention to detail is very strong with them.  If you are in the Seattle area, I highly recommend Drive Auto Sports in Everett.   

 

 

As mentioned previously, in theory this engine should be good for > 270hp at the crank, but with the stock 420 exhaust, which is undersized for this engine, the expectation was 250-260hp.  If you assume a 15% loss, backing out the wheel hp reveals 255hp at the crank.  Pretty much spot on to expectations.   

 

 

The ride home was uneventful but was far from traffic free.  Consequently, I never had an opportunity to stretch the engine's legs and can't yet comment on how it feels or if the power level is good enough for now or if I'll want to pursue a larger exhaust over the winter and find another 15-20hp. I hope to get a better idea this weekend.  

 

-John

[kayentaskier]

John,

Sounds like it's almost time to sell that 420R crate engine

[JohnCh]

The crate engine, air box, ECU, dash, gauges, switches, dampers, factory fuel system, etc.  Anyone want to build a car from my leftovers?   

 

I did a little fettling today then took the car out.  Temps were still cool and the notorious oil over-cooling on these cars was present.  As a result, I never took it over about 4500rpm but the engine felt good.  I also seemed to really begin pulling strongly at part throttle at 4000rpm.  To temporarily address the cold oil temps, I fabricated a simple block off plate out of thin aluminum.  The clamping force is strong enough that it doesn't move once in place, and it is inset a bit, which results in the end caps preventing lateral movement.  A couple of zip ties should ensure it doesn't vibrate off.  I consider this V1, and suspect I'll make it to V3 or V4 before I'm satisfied.   

 

 

 

 -John

[KnifeySpoony]

Looks like a nice design. I bet you could sell those... 

[JohnCh]

Not at the price I would need to charge   

[JohnCh]

The R-pack cars don't come with carpeting on the rear bulkhead, which unfortunately exposes the cutouts to access the upper damper bolts.  It looks a bit unfinished to my eyes, but I didn't want to drill more holes to affix aluminum cover plates.

 

 

So once again, I pulled out the 3D printer.  A Neodymium magnet is glued to the print and affixes it tightly to the chassis.  For some reason though, printing it flat was resulting in some discoloration I haven't seen before with this build plate and filament combination.  Not sure what's going on, but to keep the surface color uniform, I had to print it on its side which resulted in a little elephant's foot, but you have to look closely to see it.  The cover is easy to remove, stays in place, and requires no holes.  Not as inconspicuous as a piece of black painted aluminum, but I'll take that tradeoff.

 

 

 

 

I also discovered these really are hand-built cars.  The cover for the passenger side had to be shaped slightly differently to avoid a gap on the lower left corner.  Mirror imaged they ain't.

 

-John

[CBuff]

I am putting a pin in this posting. That cutout is something that will likely make me crazy. Might circle back upon my 420r arrival and ask for some guidance on reproducing these. (Don’t have a printer). But if it’s that unique might have to get some techsavy youngster to measure and produce once I see it.  On the positive side of things I just got a verbal confirmation that my car is on the production line (or so I’m told). 

[Vovchandr]

Didn't know that I should consider myself "fancy street trim" for having rear carpet 

 

SLR I am clearly not! 

[JohnCh]

A simpler way to do it is cut out a piece of aluminum, spray paint it black to match the panel, and if you don't want fasteners, adhere it in place with silicone.  It's a lot more trouble to remove, but that should be a rarity.  If you want to get fancy, make a buck out of an old 2x4 that's a bit smaller than the cover, then gently hammer over the edges a bit (20-30 deg angle).  That gives the cover a more finished look and provides some space for the silicone.  

 

 

 

 

[JohnCh]

1 minute ago, Vovchandr said:

Didn't know that I should consider myself "fancy street trim" for having rear carpet 

 

I have heated seats.  If you don't make fun of me for that, I'll ignore your carpeting.  Deal?  

 

[KnifeySpoony]

Hmm that doesn't look like adding lightness to me ... 

[JohnCh]

To put the weight in perspective:

 

 

 

And yes, I was surprised the weight was identical.  I even put them on the scale together to make sure the scale wasn't broken.

 

-John

 

[Vovchandr]

Awww the impossible to get key fob! Can you order an extra and ship to NY? I'll cover =)

[JohnCh]

Just order a new car and they'll give you two for free!  

 

[KnifeySpoony]

I know the key is a monster.  Chapman would is rolling over on that for sure. 

[Vovchandr]

5 minutes ago, JohnCh said:

Just order a new car and they'll give you two for free!  

 

 

Why break new cars when I can just break old ones? Seems like a lot of effort for same paperweight result. 

 

But yeah seems like nobody other than new owners can get those..

[JohnCh]

2 minutes ago, KnifeySpoony said:

Chapman would is rolling over on that for sure

 

Agree.  I'd prefer something like these 917 inspired key blanks:

 

 

 

[sltous]

On 8/19/2023 at 1:44 PM, KnifeySpoony said:

Looks like a nice design. I bet you could sell those... 

On 8/19/2023 at 2:44 PM, JohnCh said:

Not at the price I would need to charge   

If you make the part based off a drawing, the new online sheet metal shops (OSHCut or similar) are a lot cheaper than you might expect, especially if you don't get parts bent before shipping.  The parts are a lot nicer if you get them bent by a vendor though.

[JohnCh]

I received permission from Drive Auto Sports to post the video they took of a power sweep.  Gotta love the exhaust flames at the end.

 

 

-John

[JohnCh]

When I picked the car up from the dyno over 3 weeks ago, I wasn't able to drive it very much before it went to Beachman Racing for PPF and alignment.  It finally came back earlier this week, which afforded me opportunities to abuse…er, I mean to test the car.  My initial reaction wasn’t great.  Compared to the Westfield it felt big, had slow steering, and the throttle response below 4000rpm was poor, which made the low end feel soft.  Not the most auspicious start.

 

The throttle response issue is the same lean surge upon tip in I mentioned in earlier posts.  Unfortunately, the dyno operator didn’t have a chance to drive the car on the street when it was there, so this aspect wasn't addressed.  He's asked me to send logs taken this weekend so he can make changes to the map which I can then upload to the ECU and we can iterate until it's right.  

 

Once I drove the car a number of times and started to adjust to the differences, things began to change.  When driving around the tip-in issue, the engine is savage.  It loves to rev and becomes really strong as it approaches 5000 rpm.  The chassis is nice.  Steering is too slow for my taste, but it is accurate with great feel.  Traction has not been an issue, and the ride is surprisingly good.  I'll credit the CORE dampers and revise spring rates for that, although given I haven't tried the car with the stock Bilsteins and spring, you should take that comment with a very large grain of salt.  Interestingly when driving it back-to-back with the Westfield, the throttle pedal travel feels significantly longer, yet measuring the two, they are identical.  I suspect this misperception is due to the radically different shapes of the pedals.  The Westfield's is a traditional shape, whereas the Caterham's is a loop that the foot rolls across as it's pressed.  

 

 

A couple of issues have cropped up.  The capacitance fuel sensor is reading incorrectly and with some randomness.  I believe this is down to the new Hydramat, which attaches to the bottom of the fuel pump rather than the bottom of the tank like the original.  This allows it to float up, blocking the bottom of the sensor tube which is a no-no according to Centroid.  I'll address this later and will rely on the trip odometer in the meantime.  The dash has become partially detached.  I suspect this is down to overly tight tolerances in places with the scuttle.  As the chassis flexes, the scuttle puts repeated pressure on the dash and has broken the bond with the adhesive.  This is another fix over the winter, as doing it right means removing the scuttle.

 

I tested the oil temperature reading with long temperature probe that can reach the bottom of the tank near the sensor and confirmed that at running temperatures, the gauge is reading 5C too low.  I'll readjust the calibration, but until then I'll mentally add 5C to the dash reading. The oil cooler block off plate appears to be working well.  No problem getting oil up to temperature and it hasn't gotten hot when driven aggressively.