The Bastard's Build

[cvjoint]

Intro
The Bastard started life as a 2013 SRA model but has morphed to devour pavement at a faster rate. As long as it will retain its British roots and remain powered by Japanese voodoo Honda K series magic it will remain a bastard its entire life.

The build goal is to be as fun and as raw as possible to drive. To that extent, it will always keep its manual transmission and forgo the use of ABS, traction control, and other sorcery. It will also retain it's passenger seat. What's the point of having fun if you can't share the spoils? It goes without saying that another goal is to go faster but good reliability remains a major condition.

2019 Season Modifications
In the first round of modifications I swapped in an HPD engine. The K24/K20 engine nets a 58whp increase while running much cooler. The head is a stock 8th gen Civic K20Z3 piece, which should last forever with a redline lower than in the street car. This engine replaces the weakest link in the stock K24Z7 block, the cast pistons with weak ring lands, in favor of custom forged Mahle pieces. Though compression is a stock 11:1 the engine is tuned on 100 octane. Every track in Northern California has 100 octane so might as well take advantage of it. The car is used on track only. The intake design bypasses the stock snorkel which has been shown by other members to be a major restriction. This opens up the intake snorkel use for other purposes, such as an air to air charge cooler. The exhaust mounts the muffler lower to the ground to lower COG and open up the engine bay for other purposes such as an Accusump. I tested a tripple pass Dynomax muffler of this size at Laguna Seca and it passes the diabolical 90db @ 60ft sound limit. The engine mod alone yielded ~3 second a lap improvement at Thunderhill East and Sonoma raceways. The end goal is to add forced induction via a Rotrex C38R, hence many of the design parameters used in making the intake and exhaust where set for 450hp crank in a centrifugal application.

Build list
Engine: Honda Civic SI Touring Car engine by RealTime
balanced and blueprinted
11:1 comp
forged 4032 Mahle pistons
stock K20Z3 head
K24Z7 stock forged 585g steel rods with cracked rod caps
stock K24Z7 forged steel crank
stock steel liners
K20a2 oil pump
K20a2 oil pan
RealTime oil pan baffles
RRC intake manifold from JDM Civic Type R
RRC throttle body from JDM Civic Type R

Tune:
Hondata Flashpro
Blacktrax tuned
100 octane map
8,000 rpm redline
4,200 VTEC crossover

Bolt-ons:
Custom pop charger by Jim Wolf, 83mm ID to match Rotrex C38R using 5" open cone filter
Blacktrax custom intake piping
Burns Stainless custom 4 into 1 stainless steel header and exhaust optimized for 450hp centrifugal application
3" in 3" out Dynomax tripple pass muffler

Driveline:
Gear x 4th gear upgrade, stock ratio
Exedy Stage 2 Cerametallic Clutch Thick Disc
Stock K20Z3 flywheel

Other:
Keizer 15" diameter Kosmo wheels with forged centers in 10" to 14" width
Hoosier tires in 205 to 355 size
Motul 300V 15w50 oil

Before and after dyno
Atom dyno HPD vs stock.jpg
Build pictures
Atom on track.jpgIMG_2103 (1).jpg
Burns progress 1.jpgBurns finished 1.jpg

[McFred]

Looks fun. I'll be interested in seeing a Dyno with a PSI overlay. I've got a C38 sitting on a shelf but have been paranoid about the lack of "sorcery" to keep my incompetent foot from getting the rest of me in trouble.

Thanks for sharing!

[argonaut]

Very cool project. Thanks for posting, it will be exciting to watch the progress of this build and your thoughts on driving it.

[cvjoint]

The first impression is that it didn't feel much faster. I expected quite a bit more kick in the pants given the 30% increase in power to weight ratio. Perhaps that's just the way it goes when you don't increase torque by as much as horsepower. After 2 track days of getting used to it, the clock showed 3 seconds improvement so that's enough verification for me.

Overall the car felt like a momentum car with the stock 230hp and in some ways it still feels like that now with 300hp. I still get my butt kicked in the straights by today's supercars but at least I can beat the mediocre cars to pass on the straights. Top end speeds are 5 mph to 10 mph faster depending on the track. I can do 131mph at Thunderhill, but a McLaren can easily to 155mph there. Maybe it should be chucked up to the chassis that it can handle the extra power so well. It isn't noticeably harder to drive. Power is dispatched quiet easily coming out of a slow turn. The longitudinal G is still only 0.6 max in 2nd and 3rd where I believe the Hoosiers can do at least 1.3 under straight acceleration without aero. My take is that it can use a lot more power even without aero. Our high drag still dominates the experience, it's faster than supercars in slow turns, it's about as fast as supercars in the fast turns, it's slower than supercars on the straights. That to me still says it's a momentum car though it's much more well rounded now. Now, if you autocross your experience may vary. 230hp was already too much to launch on cold tires in 1st gear. I'm sure with the HPD engine even 2nd will be a bit useless on cold tires for autocross. You need tire warmers to use the power in autocross and 0-60s.

So I say if you have a C38 and can get your tires up to temp, use it! Power is our number one tool to overcome drag at high speeds. But if you use the car only on the road or for autocross I can see why the extra power might not play in.

Unexpectedly the car cools much better with the 4 port head. Another very nice surprise is the symphony of true VTEC. The true VTEC cam is on another level compared to the tame one in the downsized VTEC of the K24Z7 head. It sounds like motorsport ought to! It also backfires in canon like bass explosions on downshifts, which I thought was not possible with a tripple pass muffler. I don't know where the pops on downshifts come from, maybe the tune or the cam.

I expect 18 psi @ 7,600 rpm with the Rotrex C38R. I predict this based on the 10 rib 90mm pulley I bought from Jaydee and his forecasting tables. Power will be only about 400whp due to the restrictive muffler I use but should be flat from 6000 rpm to 7,600.

[cvjoint]

The Bastard has wings now. I wanted an aero car for some time but cautiously delayed it until I could work in some supporting modifications. The first obstacle was that the rear upper hoop to which rear wings mount has little support. The second was that Honda's engines are wet sumped, and that sump is designed for a sporty economy car at best. Hence I had the hoop reinforced by adding support beams from hoop to frame. This was not straight forward as they had to be made removable to get the engine out. At this point I reinforced the frame from Atom 3 spec to Atom 3.5 and even added some Atom 4 reinforcements. In total I added 6 extra support beams and numerous gussets. Next, to ensure adequate oil pressure I added an Accusump. However, I was afraid it's too hot for it by the header, so I had the header and exhaust ceramic coated. When it was all set and done I added the dual element 71' APR wings using Ciro supports. These have proved to be a bit on the flimsy side, especially the front so future modifications to the wings will come. Cooling has been heavily impacted, car runs about 20* hotter than before, another reason to revise the front wing design.

The aero delievered the goods. I beat my Sonoma Raceway track record by 1.8 seconds, went from 1:45.8 to 1:44.02 and did so in 5 degree higher ambient and with 30 heat cycles on the front Hoosiers (instead of the 11 heatcycles I had running without the wings). Rear tires were at 10+ heatcycles. Even better two laps later I was only a tenth slower and passed thee cars doing it, so there is a lot of speed in reserve. The best lap is this one https://www.youtube.com/watch?v=WTz98kCCjTA and the one with traffic is this one https://www.youtube.com/watch?v=wVNkPo8xYd4. I had the front set at 20* and the rear at 30*. The front wing cannot be run at the lowest setting, which is 10*. It hits the nosecone. The highest setting is 52*. Top speed dropped by a little over 3 mph. Subjectively the car feels very planted but it's not magic. Once I add further bracing I'll try more aggressive angles of attack. The Accusump works well, and works hard. See how often the light turns on, almost every corner.

Best lap:

A tenth slower but passing three cars

[SAD]

subbed for reading later

[Atommatt]

[ShakaShaun]

you're a madman! Thanks for the new screen saver.

[I want an atom]

Next, to ensure adequate oil pressure I added an Accusump. However, I was afraid it's too hot for it by the header, so I had the header and exhaust ceramic coated. The Accusump works well, and works hard. See how often the light turns on, almost every corner.

Any advice on the accusump? Where to purchase, how to install (or did you have a shop do it)? I'm worried that once I become a decent driver and get some big-boy rubber I'll break the motor without having this. I'd rather do things right...

[cvjoint]

Any advice on the accusump? Where to purchase, how to install (or did you have a shop do it)? I'm worried that once I become a decent driver and get some big-boy rubber I'll break the motor without having this. I'd rather do things right...

1. I say buy it straight from them. I like to avoid middlemen.
2. My high pressure 55-60psi electric pressure valve seems to work well with the K20a2 oil pump.
3. Using higher weight oil increases oil pressure and allows the Accusump to discharge less and refill faster.
4. The 3 quarter thank, but not the high pressure one, is ideal if you can fit it.
5. I had a shop install it.
6. The install is made using a sandwich adapter at the oil filter.
7. I had them mount the discharge light up in the cabin along with an on-off switch. When the oil is hot after exiting the track the oil pressure will drop at under 55psi at idle and the Accusump will discharge. The manual on/off switch allows me to turn it off once I hit the paddock so it doesn't fill the oil pan.
8. Some folks recommend a manual valve instead, and there are cases of the electric one failing. Mine has worked thus far but I don't have a lot of mileage to report.
9. You can still forget to turn on the Accusump and blow the engine. Something that you can't do with dry sump. Food for thought.
10. Other benefits of Accusump are preoiling on cold start ups and safety added if you run low on oil or rupture an oil line. This one is just to get to no. 10.