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20b build - Twin Vision Studios Racing partners with ChipsMotorsports on 20b build

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20b build - Twin Vision Studios Racing partners with ChipsMotorsports on 20b build

Old 06-26-11, 07:12 PM
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20b build - Twin Vision Studios Racing partners with ChipsMotorsports on 20b build

Twin Vision Studios Racing is partnering with ChipsMotorsports on a 20b build for the TVS race car.



It was time to make the move on the race car from the 13b to the 20b. This has always been one of my 'end game' goals as a rotary/rx7 fan, and it is time to 'get er done'. Below are some basics but there is too much to cover in one post, so I will flush out details as I post on progress.

Goals of the 20b build
Many goals but I will simplify for this post:

Personal goal end game
○ Always wanted to build an drive a 20b

Reliability in road racing
○ Asking less out of a 20b vs 13b at the same power level
○ Preparationm for running more enduros
○ Dry sump

Performance
○ Can easily run the proper power for my power/weight with little effort
○ Much better TQ curve
○ Much more tunability in terms of power/boost in the power range we need to run


Engine builder - Chip Ursu (http://www.chipsmotorsports.com)
I did a lot of research and there are many good builder options that I looked at. However, I came across some fantastic work that I saw online and that connected me with Chip. After a few conversations with Chip I decided to partner with ChipsMotorsports to build the new racing 20b power plant for the race car. We saw eye-to-eye on a lot of things and I connect with his attention to detail and passionate approach to his work.

Starting block
Since I am not going to run a lot of power, I was not really concerned about the stronger e-shaft and dowel-pin areas of the later blocks, so I opted for a early pre-A block to save some $$. The good news was many parts of the block were in great shape (rotors, rotor housings, e-shaft), but he bad news was some of the irons were not in good shape. The front plate had a collapsed water jacket wall, and apparently this can be common on early code blocks. If I were to do it again, I would just spend the extra $$ and buy a later code block.

Engine Modifications
There are a few racing modifications I wanted to apply to this build, but yet keep it modest since we are not doing any thing extreme with power output. The mods are focused on reliability in road racing versus power:
Oil mods
Rotor mods
3mm seals
Competition bearings where possible
Intake porting - probably none based on our power goals
Exhaust porting - minor porting but no timing change (no port height change, just port width)

Turbo System - A-Spec Tuning (http://www.a-spectuning.com/)
Sean at Aspec tuning provided fantastic support for the A-spec 500R kit we ran on the 13b. There we-re multiple times where they came through huge for us while preparing for races. We are still researching the best turbo to use for what we plan to do with the boost curve.
Sean, I will be contacting you on this soon ;-)

Power output - around 450 rwhp (class rules)
Keep in mind we are bound by NASA class rules for ST1 (basically power/weight formula), and based on my cars weight and a few points adding mods, our pwr target is around 450 rwhp. It may change a bit after the car gets sorted, based on any changes in weight, but not by much. We have very specific plans on how we want the engine to make power and will leverage the boost curve to do it.


Oil System - Dry sump
Right now the plan is to run the mazda dry sump system. I will post more details on this as we start to put the dry sump system together.

Engine Placement
Recent rules change for my race class (ST1 in NASA) allow us some freedom to cut the firewall allowing the engine to be moved back. We will have a lot to work out in engine position, but right now we plan to move it back somewhere between 5 to 7 inches, and get it down as far as possible. There is still some clarification to NASA rules I need to inquire about, but as of right now it states you can NOT modify the 'subframe'. So based on that the subframe stays unmodified (stock) and we will make custom engine mounts that fit to the stock subframe engine mount locations. This may change based on what NASA considers the subframe versus what mazda calls a subframe on our chassis.

Transmission/clutch setup
Right now staying with my t-5 dogbox setup that uses the stock FD manual bellhousing and clutch mechanical setup. Basically all this stays the same as before, however the clutch may end up needing to be upgraded.

ECU - Motec m84
I already run the motec PDU to power the car (and I LOVE it) so wanted to stay with motec for the ecu, bu they are on the higher price range. However, they recently came out with the m84, a more affordable ecu that still is very powerful.

Ignition - TBD
I am still researching ignition systems.

Here are some initial pics:

Starting block



Rotor housings before 'Chip clean up'


Rotor housings after 'Chip clean up'


Tension bolts before 'Chip clean up'


Tension bolts after 'Chip clean up'


E-shaft call cleaned up



I will post more pics as they become available.
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Old 06-26-11, 07:23 PM
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I like where this is heading.
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Old 06-26-11, 08:14 PM
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Looking good Damian!
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Old 06-27-11, 08:41 AM
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MMmmmmm... shiny!!!

definitely looking forward to seeing this project unfold.

-b
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Old 06-27-11, 08:43 AM
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The TVS car LIVES, who knew

On serious note stop effing around and go kick some ST1 azzzzzzzzzz.
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Old 06-27-11, 09:47 AM
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Talking

Originally Posted by Fritz Flynn View Post
On serious note stop effing around and go kick some ST1 azzzzzzzzzz.
Geeze, the people in this forum wouldn't even cut their own mother any slack when it comes to motorsports...

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Old 06-27-11, 10:12 AM
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Originally Posted by wrankin View Post
Geeze, the people in this forum wouldn't even cut their own mother any slack when it comes to motorsports...



We don't care about engines, brakes, susp etc......RESULTS are all that matter so belt your tookus into your FB, FC or FD and drive
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Old 06-27-11, 10:44 AM
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After seeing pictures on FB a while back, I was wondering when your build thread would hit the Club. G'luck, and keep us updated Damian.
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Old 06-27-11, 11:56 AM
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Nice.
Can't wait to see more as it progresses.
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Old 06-27-11, 03:02 PM
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Funny,

I was over at Shpnout's place yesterday chatting about race cars and such...he said now that I have a solution for my transmission problems I should stick a 20b in my FD...

Damian, thanks in advance for all the problem solving and parts sorting that you've already done and or will do during the process of this build!

Guy
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Old 06-27-11, 07:47 PM
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Originally Posted by Fritz Flynn View Post
The TVS car LIVES, who knew

On serious note stop effing around and go kick some ST1 azzzzzzzzzz.
sup fritz!!! yea I am working on it :-)

by the way, once I get the car sorted out, I plant to make a trip back to VIR to run with you guys!!
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Old 06-27-11, 07:49 PM
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Originally Posted by finger lock View Post
Funny,

I was over at Shpnout's place yesterday chatting about race cars and such...he said now that I have a solution for my transmission problems I should stick a 20b in my FD...

Damian, thanks in advance for all the problem solving and parts sorting that you've already done and or will do during the process of this build!

Guy
hehe no problem ;-)
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Old 06-27-11, 07:53 PM
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It's about time you posted a build thread, I have been waiting since you said you were going 20B...LOL...
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Old 06-27-11, 08:13 PM
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update - rotors

Chip finished some prep on the rotors. I decided to go 3mm (wire EDM cut) and some 'race' clearancing to prevent the rotor tips from hitting the irons under high rpm/load from rotor 'wobble'. I do not plan to run the engine very high rpm, but the clearancing is cheap insurance for the irons. I will be using stock 3mm mazda seals.

Here are some pics and a video:

Rotors before Chip's cleanup and prep:


Rotors after Chip's clean up and prep:





Video of clearancing:

http://www.youtube.com/watch?v=GyfcS...&feature=share
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Old 06-27-11, 08:38 PM
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? Not sure I ever seen them machine the surface of the rotor that way before. Is the clearance for high rpm use?
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Old 06-27-11, 09:00 PM
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Originally Posted by IAN View Post
? Not sure I ever seen them machine the surface of the rotor that way before. Is the clearance for high rpm use?
I mention it at the top of the post :-)

>>some 'race' clearancing to prevent the rotor tips from hitting the irons under high rpm/load from rotor 'wobble'

In my case it is really just precautionary rather than a necessity since I will not be running very high rpm (prob 8500 max depending on how the power/tq tuning turns out).

Basially, at high rpm, along with other conditions in combination to high rpm, the rotor may 'wobble' enough for the tip to touch the plate surface. A very minor amount of surface reduction, especially at the tips, will prevent this from happenning.

Although it it tends to be a rare condition, we actually saw this on one of my previous 2 rotor race engines.

I am kind of over simplifying it for the sake of this post, but there are other factors that play in to a rotor hitting a iron beyong just high rpm, like balancing, bearing clearance, et.
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Old 06-27-11, 09:39 PM
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A few goodies from Rotary-Works came in today, the TB elbow and the exhaust sleeves.

They make a nice TB that can fit stock FD and 20b TBs. It also comes with a port for an air temp sensor.
http://www.rotary-works.com/mm5/merc...gory_Code=THBD



The titanium exhaust sleeves are nice as well.
http://www.rotary-works.com/mm5/merc...gory_Code=TITP



In case you have not seen stock 20b exhaust sleeves before, I posted a pic below.

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Old 06-27-11, 09:50 PM
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Originally Posted by gmonsen View Post
Hey, Damian, great build and about time. I met Chip this year and think he's a great choice. I'm using a Chipsmotorsport lighter right now light up! Really like your goals.450 whp let's you build a real jewel even though its to suit the racing rules. Should be a torque monster.

Gordon
hey gordon!! I am very excited about the build even though I know its a long haul before the car is ready to race. ;-)
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Old 06-27-11, 11:47 PM
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very nice attention to detail.

I don't want to sound critical but would like to offer some advice from my experience. I have a few suggestions from my 4 years running the dry sump 20b rx7 turbo roadracer. You'll need a big nascar rad and two big oil coolers .

The 20b will last way longer if you plan on running it with a 7-7500 rpm redline. Especially an A motor. With all the torque there is really no need to rev it higher. With our 700 hp gt42 (1.15)the power plateau's after 7500. and its torquey kicking at 3600 rpm when the motor was fresh. To make 450 hp will require a way to small turbo which will not make a lot of power past 6000 rpm anyway. If there is a way to get it past the rulebook you run in your class I would go with a gt42 .(90-1.05)which at say 12 psi will make 550 ish hp with no stress or heat from the backpressure you would get from a small turbo. It will still kick at 32-38000 rpm and thats about right if you come off the corner with 3000 rpm. Any power below that will just spin the tires off of most corners .

The high rpm is really hard on bearings, side/corner seals, rotors/ etc. We ran ours for about 60 hours before it was losing power. With 8500 as a redline I would say 20 hours and its time for a rebuild.
I hate to see you spend thousands on all the right stuff , do all the right mods, and rely on a known problem 3 rotor as a race engine. For a street engine no problem. Please get a c + motor and use these "a" specific parts as spares!


wb
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Old 06-27-11, 11:53 PM
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FYI Damien, be careful with your early series e-shaft. Even though your not looking for a ton of power, it's the instant torque creation that kills the early engines e-shafts and not necessarily the power. A term I haven't heard or used in a long time is "snap torque". For your power goals, the turbo you will be using is gonna spool very fast creating a lot of torque early. I know of a forum member years ago (Rxman720b) that had an early engines e-shaft break on a smallish turbo.


Also if your trying to save money, you can easily run the Yukon coils and will support that power level all day long. They have built in igniters if your Motec doesn't. Can't wait to see this thing finished.
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Old 06-27-11, 11:55 PM
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very nice attention to detail.

I don't want to sound critical but would like to offer some advice from my experience. I have a few suggestions from my 4 years running the dry sump 20b rx7 turbo roadracer. You'll need a big nascar rad and two big oil coolers .

The 20b will last way longer if you plan on running it with a 7-7500 rpm redline. Especially an A motor. With all the torque there is really no need to rev it higher. With our 700 hp gt42 (1.15)the power plateau's after 7500. and its torquey kicking at 3600 rpm when the motor was fresh. To make 450 hp will require a way to small turbo which will not make a lot of power past 6000 rpm anyway. If there is a way to get it past the rulebook you run in your class I would go with a gt42 .(90-1.05)which at say 12 psi will make 550 ish hp with no stress or heat from the backpressure you would get from a small turbo. It will still kick at 32-38000 rpm and thats about right if you come off the corner with 3000 rpm. Any power below that will just spin the tires off of most corners .

The high rpm is really hard on bearings, side/corner seals, rotors/ etc. We ran ours for about 60 hours before it was losing power. With 8500 as a redline I would say 20 hours and its time for a rebuild.
I hate to see you spend thousands on all the right stuff , do all the right mods, and rely on a known problem 3 rotor as a race engine. For a street engine no problem. Please get a c + motor and use these "a" specific parts as spares!


wb
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Old 06-28-11, 12:16 AM
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>>I don't want to sound critical but would like to offer some advice from my experience. I have a few suggestions from my 4 years running the dry sump 20b rx7 turbo roadracer.

Please, do be critical!! that is part of why I post the build like this, to allow experienced builders/racers comment on any part of it :-) thatnks for all the input, that is what I am looking for.

>>The 20b will last way longer if you plan on running it with a 7-7500 rpm redline.

this may end up beign the case, as I initially wanted to only rev it to 7500ish, but part of what was going to dictate that for us was what the optimized power was based on gear, et. So it may end up that we are only reving to 7-7.5K in the end anyway.

>>With our 700 hp gt42 (1.15)the power plateau's after 7500
>>The high rpm is really hard on bearings, side/corner seals, rotors/ etc. We ran ours for about 60 hours before it was losing power. With 8500 as a redline I would say 20 hours and its time for a rebuild.

the one thing I want to say here is that you are really not comparing apples to apples, 450 hp vs 700 hp... you can not compare the wear the same. and we are modifying the boost curve to manipulate power output per rpm, so its hard to compare to a straight boost curve up to max power/rpm... in other words, we will be dropping boost as rpm goes up, so there will be very little boost at high rpm.

>>To make 450 hp will require a way to small turbo which will not make a lot of power past 6000 rpm anyway.

I know it sounds funny, but this is exaclty what we want!! We need it to bleed off power at higher rpm to stay below our pwr/weight for rules. This is part of what we are working out. A lot of it has to do with porting as well, basically none on intake side, and maybe a bit on exhaust to help spool.

>>If there is a way to get it past the rulebook you run in your class I would go with a gt42 .(90-1.05)which at say 12 psi will make 550 ish hp

Way to much power lol like 100 hp too much!! lol. this is part of whay the setup is goign to be a challenge, finding the combination of turbo setup + boost curve tuning to do what we want. and I am sure it will not be perfect the first time lol

but we did look at a few specific 42 setups to get it to do what we want, but still a lot of reasearch to do there.

>>Please get a c + motor and use these "a" specific parts as spares!

At 700hp that you are making I see the argument, but not at 450 hp. But then again time will be the true test. It will have C block plates by they way, only the thick center plate is from the original block.
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Old 06-28-11, 12:26 AM
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>>FYI Damien, be careful with your early series e-shaft. Even though your not looking for a ton of power, it's the instant torque creation that kills the early engines e-shafts and not necessarily the power. A term I haven't heard or used in a long time is "snap torque". For your power goals, the turbo you will be using is gonna spool very fast creating a lot of torque early. I know of a forum member years ago (Rxman720b) that had an early engines e-shaft break on a smallish turbo.


Yeah tvon, i hear ya on the e-shaft, it has more to do with tq than hp. It may end up a problem, we shall see. I may change it for a later e-shaft if I get enough push back on using the current one. the only part i always want clarification on when i hear things like that is roadracing vs drag...I can easily see it in drag racing, but in roadracing, even aggressive accel out of a turn is still failry smooth compared to a drag launch or accel.

>>Also if your trying to save money, you can easily run the Yukon coils and will support that power level all day long. They have built in igniters if your Motec doesn't.

Hey, now that is good info, thanks!!! I need to look into those. I think the motec ecu just sends the signal, you need outside coils and igniters.
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Old 06-28-11, 01:39 AM
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Great thread and I can't wait to read more.

Only item I would mention is that the Rotary Works Throttle Body is NOT EVEN CLOSE to being drop in for a FD engine. On 3-rotors they fit nicely from what I have seen.
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Old 06-28-11, 01:46 AM
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>>Only item I would mention is that the Rotary Works Throttle Body is NOT EVEN CLOSE to being drop in for a FD engine. On 3-rotors they fit nicely from what I have seen.

Ops, that was supposed to say TB ELBOW, not just TB. I am not using their tb, just the tb elbow. I will be using the stock 20b tb ;-)
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