The Bastard's Build

If you race your Atom or use it hard on track, here's a place to discuss strategy and swap tips.
User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

The Bastard's Build

Post by cvjoint » Sat Dec 21, 2019 8:52 pm

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 End Status
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 USDM 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 USDM 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 105 RON octane. Every track in Northern California has 105 RON 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 opens up the engine bay for 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 goal for 2020 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
105 RON 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 125mm open cone filter
Blacktrax custom intake piping
Burns Stainless custom 4 into 1 stainless steel header and exhaust optimized for 450hp centrifugal application
75mm in 75mm 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 or Avon slick tires in 205mm to 355mm size
Motul 300V 15w50 oil
3QT Accusump

Aero:
APR carbon fiber GTC 1000 dual element front and rear
Design by CIRO
Main cord 1800mm x 250mm
Second element 1800mm x 100mm
Max AOA 52*
Rear element has a carbon fiber gurney flap
100mm extension to clear dirty air from roll over bar
20191123_164718.jpg
20191123_164718.jpg (2.89 MiB) Viewed 2825 times
20191123_165501.jpg
20191123_165501.jpg (2.51 MiB) Viewed 2825 times
20191027_085208 plate.jpg
20191027_085208 plate.jpg (2.04 MiB) Viewed 2825 times
Dyno stock rated 230hp cranck tested 190whp
HPD motor rated !secret! tested 248whp equivalent of 300 crank hp if 230hp stock rating is true
george AFR.png
george AFR.png (95.11 KiB) Viewed 2822 times
george atom 2 (1).png
george atom 2 (1).png (93.67 KiB) Viewed 2822 times

User avatar
Sir Nick
Posts: 1554
Joined: Tue Sep 06, 2011 2:41 pm
Location: Yate, Bristol, UK
Contact:

Re: The Bastard's Build

Post by Sir Nick » Sun Dec 22, 2019 5:01 am

Pocket rocket!
Atom 3.5R, Black+Red flashes, CF front & rear wings, CF bonnet & mud guards.  Bristol

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Thu Jan 09, 2020 6:20 am

These are the first pictures of the 2020 goodies coming up for install.

First up on petrolhead santa's list is the oil cooler. It took a lot of digging to sort out this solution. The V8 side pods are different than the 3.5R sidepods which are again different from the 3S/3RS sidepods. In the end, the 3.5R sidepod solution was the one to go for. It houses an oil cooler on the passenger side as does the V8, but without the associated dry sump bits that fill the sidepod. The 3S/3RS have a water cooler there. After giving it some thought I decided I do not want the dry sump tank to be in the sidepod, instead I'm going for a dry sump tank that is very tall for better air/oil separation and large capacity. With this cooler I free up the SRA inboard mounted heat exchanger to be removed or used in a different application. More on this as I sort it out.
oil cooler 1.jpg
oil cooler 1.jpg (325.96 KiB) Viewed 2652 times
The sidepod has always been the final solution for me. I figure the inflow and outflow are great, and can surpass the SRA fan solution above 50 mph. I average about 80 mph on track. Furthermore, my SRA oil cooler is having some issues so I would have to spend some money to troubleshoot anyway. The Skunkwurx solution was not ready yet and I love the OEM quality anyhow.
oil cooler 2 lq.jpg
oil cooler 2 lq.jpg (499.33 KiB) Viewed 2652 times
Grille protection from factory is sweet indeed. Pod looks top notch grade.
oil cooler 3.jpg
oil cooler 3.jpg (263.84 KiB) Viewed 2652 times
There is lots of room in the pod but I'll try to keep it empty to maximize airflow through the core. Core thickness is 2" which imo is the point where diminishing returns to increasing core size set in, even for front mounted heat exchangers.

Worst case scenario I will still need extra cooling capacity, then I'll add the existing SRA oil cooler inline as an auxiliary. For now I'm going with just this one to maximize oil pressure.


The water cooling side of things gets interesting. Since I opted for the oil cooler on the passenger side pod the only option on the driver side pod was a water to air heat exchanger for the blower/turbo. This is true of either 3.5R or 3S/3RS. For many reasons I'm opting for air to air charge cooling which means the driver's side heat exchanger has to be something else. Besides, I'll need lots of engine water cooling to run for up to 25 minutes continuous in 40C+ weather. To conclude, the driver's side pod has to be a second water radiator for the engine. I decided to re-purpose the supercharger charge cooler as a secondary radiator.
water cooler 3.jpg
water cooler 3.jpg (32.77 KiB) Viewed 2652 times
The small inlet/outlet size dictates parallel connection in the water system so as to not limit water flow rate.
water cooler 2.jpg
water cooler 2.jpg (26.57 KiB) Viewed 2652 times
The factory pod and heat exchanger is extremely well built. The core is thick with some very nice baffling and strengthening ribs.
water cooler 1.jpg
water cooler 1.jpg (37.59 KiB) Viewed 2652 times
This pod usage will be a bit unconventional, but then again, the Atom is unconventional through and through!

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Sat Jan 11, 2020 12:07 am

Super excited to say the baddest boy of them all, the new Rotrex C38R is here. I've wanted a Rotrex Honda powerplant for something like 20 years. The time has come!
20200108_201831 small.jpg
20200108_201831 small.jpg (38.4 KiB) Viewed 2581 times
I experienced a Rotrex C30 in a Honda S2000 and it was intoxicating. It built up power like an exotic high reving engine and didn't whine like some of the other supercharger solutions. In the Atom it helps that it has a very tiny footprint for the amount of boost it can generate. Jaydee has already taken his K22 build to over 21 PSI and is far from reaching the peak impeller shaft speed.
20200108_201951 small.jpg
20200108_201951 small.jpg (34.2 KiB) Viewed 2581 times
Size wise it's very similar to older C38-92.
20200108_202720 small.jpg
20200108_202720 small.jpg (46.71 KiB) Viewed 2581 times
I had the guys at Jackson Racing rotate it for the Atom TTS bracket.
20200108_201919 small.jpg
20200108_201919 small.jpg (36.57 KiB) Viewed 2581 times
83mm inlet ID, 53mm outlet ID. I have a custom built Jim Wolf pop charger built for matching the 83mm inlet. On the outlet side the TTS air to air intercooler is 2" OD which is a bit small. Will have to talk to my tuner about options here.
20200108_201854 small.jpg
20200108_201854 small.jpg (36.35 KiB) Viewed 2581 times
Planning to run it very conservatively at only 78.6% of its max speed in the first year. My block is fairly high compression at 11:1 and will run it in road course application which is fairly high strain. For that reason I'll be keeping the piston speeds low with 7,600 rpm redline and run a fairly big pulley. The 90 mm pulley calculation: (7600 x 139.7 x 6)/90=70,781rpm out of 90,000 rpm max allowed by Rotrex C38R (78.6%). I'm estimating about 400 whp, and 300 wtq @ 16 psi which should be fairly reliable on 105 RON octane and on par with Atom 3RS and V8 based on the dyno sheets I've seen.
20200108_201821 small.jpg
20200108_201821 small.jpg (32.87 KiB) Viewed 2581 times
Eventually I'll have to rebuild the engine, and then I'll go for low compression pistons and uncork the Rotrex to the tune of 500whp @ 24 psi.

Karl V

Re: The Bastard's Build

Post by Karl V » Sat Jan 11, 2020 8:51 am

This is getting interesting. Nice work!

:pop:

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Tue Jan 14, 2020 5:40 am

Karl V wrote: Sat Jan 11, 2020 8:51 am This is getting interesting. Nice work!

:pop:
TY!

It will be interesting for sure. There are many custom parts, I'll be shocked if it all runs perfectly on the first outing. We don't really know what the K24Z7 rods can hold since no one pushed them with forged pistons, and hardly anyone tried the new Rotrex C38R. Excited but trying to contain the excitement at the same time. >:D :angel: >:D :angel:

Anon

Re: The Bastard's Build

Post by Anon » Tue Jan 14, 2020 6:54 am

Thanks for sharing. Do you know where we can find a manual of the Honda engines, preferably the K20C that shows efficiency with stock rods, pistons, inlets etc?

I had a brief look but couldn't find it.

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Tue Jan 14, 2020 7:26 am

simonrhart wrote: Tue Jan 14, 2020 6:54 am Thanks for sharing. Do you know where we can find a manual of the Honda engines, preferably the K20C that shows efficiency with stock rods, pistons, inlets etc?

I had a brief look but couldn't find it.
The most useful sources for the K20C1 I have found publicly have been 4 piston racing and Hondata:
http://blog.jepistons.com/comparing-hon ... 0a-series-
https://www.civicx.com/threads/hondata- ... 92/page-34

I suppose I forgot workshop manuals exist, you bring up a good point. I haven't gotten one in years, Helm, Chilton, Haynes used to be popular.

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Wed Jan 15, 2020 1:09 am

Supercharger Heat Exchanger (TTS air to air)

This was not an easy choice, the OEM solution is well thought out, the TTS solution is proven with turbo and Rotrex, I even had the choice of getting a custom build from another owner, and then there is full custom.

In the end I decided that for road course use the air to air solution is hard to beat. At my local tracks I average between 75 mph and 90 mph which is plenty of airflow. In time trials I never start from a stop since there is a warm up lap. Given the airflow going water to air seemed like adding too much weight and complexity for the same outcome.

There is no ready made solution to use the airbox for anything other than a ram air intake or an air to air intercooler. As with ram air, I'm guessing, the gains are 0.005 bar at most Atom speeds, it is hardly worth the trouble. A custom water to air solution in the intake box location is a bit too high for center of gravity considerations. A light air to air heat exchanger mounted high is hardly a COG penalty, plus it always gets cold air and airflow. This means both sidepods can be used for engine oil and water cooling which I'm guessing will be the primary power output limitation in California.

The final thought was that if I'm willing to add some drag I can always mount a higher custom air to air core above the engine to increase boost pressure and reduce charge air temps. We'll see how good the TTS unit is.
20200108_203505 small.jpg
20200108_203505 small.jpg (59.16 KiB) Viewed 2466 times
The TTS solution has the Rotrex traction fluid heat exchanger core sandwiched behind the core next to the outlet. I decided to mount the fluid cooler somewhere else to maximize outflow through the core and therefore charge cooling. Hence, my core has no mounts for the fluid core.
20200108_203416 small.jpg
20200108_203416 small.jpg (53.09 KiB) Viewed 2466 times
My tuner said we can remove the outlet pipe and weld in one to match the C38R hot side dimensions (53mm ID) to optimize flow.
20200108_203649 small.jpg
20200108_203649 small.jpg (43.63 KiB) Viewed 2466 times
The cold side outlet is already 64mm and perfect for my RRC 64mm intake manifold/throttle body. 64mm should offer minimal restriction to 550hp. The limiting factor I think will be the size of the core, not the piping.
20200108_203555 small.jpg
20200108_203555 small.jpg (34.82 KiB) Viewed 2466 times

User avatar
Peter255
Posts: 1690
Joined: Thu Jul 25, 2013 9:44 am
Location: Berkshire
Contact:

Re: The Bastard's Build

Post by Peter255 » Thu Feb 13, 2020 11:36 am

Looking forward to seeing where you can mount this... :tu:
Atom 4, Clio v6, & some other cars obviously.

User avatar
speedmachine
Posts: 1244
Joined: Tue Jun 19, 2012 10:20 am
Location: Netherlands
Contact:

Re: The Bastard's Build

Post by speedmachine » Sun Feb 16, 2020 6:51 pm

Great stuff, keep us updated

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Thu Feb 20, 2020 6:24 pm

Peter255 wrote: Thu Feb 13, 2020 11:36 am Looking forward to seeing where you can mount this... :tu:
Indeed, the Rotrex C38R does not fit without work, it's bigger in some dimensions than the older top dog C38. The shop had to remove the RRC intake manifold, mill it, and weld it back up for clearance.

Car should run by mid March. :vroom:

User avatar
cvjoint
Posts: 179
Joined: Fri Mar 16, 2018 6:23 pm
Location: Cockfosters
Contact:

Re: The Bastard's Build

Post by cvjoint » Fri May 08, 2020 8:46 pm

Sneak peek at The Bastard's new mane.

Image
Attachments
20200506_160832 (1).jpg
20200506_160832 (1).jpg (3.19 MiB) Viewed 2187 times

User avatar
Peter255
Posts: 1690
Joined: Thu Jul 25, 2013 9:44 am
Location: Berkshire
Contact:

Re: The Bastard's Build

Post by Peter255 » Sat May 09, 2020 7:52 pm

Thanks for the update. :)

More pics please! :tu:
Atom 4, Clio v6, & some other cars obviously.

thrlskr
Posts: 8
Joined: Thu Feb 27, 2020 10:33 pm
Contact:

Re: The Bastard's Build

Post by thrlskr » Fri May 22, 2020 12:36 am

You do still run the intake cover with that intercooler?

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests