Jump to content
Sign in to follow this  
KoneKillah

99-00 Miata JDM engine swap

Recommended Posts

I will start a build thread on our new car, currently called LR2 (Love Racing 2), once I finish the the build schedule. I need to first figure out what route to go with the engine.

 

I also want to be as transparent as possible with the build so I can focus on the racing.

 

I will defer to Rule # 4.5.5.1

 

image.png.f11668df8f8214d357b36aceb97fbfb7.png

 

For our car (1999 Miata w/ Hard-S package) this rule refers to the BP5A engine that came in 98-00 JDM 1.8L Miatas.

 

The BP5A engine is different from the USDM engine by only one part, the intake camshaft. The Parts Badger guys claimed it also came with the coveted "Square top" intake manifold but they were mistaken. That intake manifold only came on JDM VVT cars.

 

The rated power difference as stated by the official sources is indeed within 3% between the USDM and JDM engines. One could lawyer their way through whether the testing and rating standards are the same in Japan as they are in the US and maybe figure out the power difference is more that 3%. But hey, Free camshaft!

 

For reference the exact same camshaft is used in the Mazdaspeed Miata and has the same part number: BP5A

 

The issue here really comes down to cost for us. We bought the car for a cool grand with a running (barely) engine. I already have points allocated for an intake manifold (25pts) and a header (25pts).

 

The way the rule is written, and has be clarified in the tech knowledge base is that to run this camshaft I can either; 1. Buy the JDM engine for $1200-1700 and take no VPI points or 2. Pay $270 and take a 50 point hit in VPI. 

 

I want to be competitive with this build so I am inclined to just pony up the cash. But first a few questions:

 

Miata guys: is it worth the cost? The lift is the same as an exhintake mod (0.025" or so more than the BP4W cam) but it has a bit more duration. What does this translate to in actual power with a tune? Has anyone done back to back pulls with the cam swap alone? (Exhintake or BP5A as they are extremely similar) 2-3 hp and I'll pass, 6-8 and I'll throw down the money.

 

Tech guys: If I do decide to go this route, what is the formal process for getting the swap approved before I show up for the first annual tech inspection? Is there a form to fill out? What specific documentation do you need to see? Let me know what y'all need to see to make it legit. I don't want to surprise anyone.

Share this post


Link to post
Share on other sites
24 minutes ago, Wink said:

https://mazdaroadster.net/showthread.php?3308-BP5A-MSM-Intake-Cam-Swap-Dyno-Results

 

There's back to back testing.

 

I suppose it depends on where you plan on spending the remaining points. If you're going for the square top, is this a high horse intended car (no bars, aero, coolant reroute)?

 

No bars? Aero yes. Reroute yes.

 

Skunk 2 IM and Racing beat 4-1 is the plan. 

 

Obviously the cam would be amplified by both of those.

Edited by KoneKillah

Share this post


Link to post
Share on other sites
18 minutes ago, shanehutton said:

Just remember, if you are taking the hit for cam points you may as well go for a much bigger cam.

 

Well I don't have to take a points hit for it at all if I just pay for the JDM engine. Which is why I want to get the swap approved before heading to tech. 

 

 

Share this post


Link to post
Share on other sites
24 minutes ago, KoneKillah said:

 

Well I don't have to take a points hit for it at all if I just pay for the JDM engine. Which is why I want to get the swap approved before heading to tech. 

 

 

We've been buying them off eBay with the six speed.  Roughly the same price as the USDM BP4W if you sell the trans.

  • Like 1

Share this post


Link to post
Share on other sites
57 minutes ago, LuckyKid said:

We've been buying them off eBay with the six speed.  Roughly the same price as the USDM BP4W if you sell the trans.

I see one right now with no trans. May have to snag it.

 

What documentation did you have to provide to tech?

Share this post


Link to post
Share on other sites
53 minutes ago, KoneKillah said:

I see one right now with no trans. May have to snag it.

 

What documentation did you have to provide to tech?

Just keep all receipts.  Make sure it includes the accessories on the motor.

Share this post


Link to post
Share on other sites

The engine swap is 50 points even if you don't make any extra power.  If all you get is the cam and you already have an engine then it isn't helping at all.  If you are going to buy an engine and go through all that why not use an ecotech?  Are they not way faster?

Share this post


Link to post
Share on other sites
8 minutes ago, shanehutton said:

The engine swap is 50 points even if you don't make any extra power.  If all you get is the cam and you already have an engine then it isn't helping at all.  If you are going to buy an engine and go through all that why not use an ecotech?  Are they not way faster?

The JDM engine is within the 3% rule and therefore 0 pts

  • Like 1

Share this post


Link to post
Share on other sites
14 hours ago, KoneKillah said:

 

No bars? Aero yes. Reroute yes.

 

Skunk 2 IM and Racing beat 4-1 is the plan. 

 

Obviously the cam would be amplified by both of those.

350 Base

40 Coils

20 Swaybar (front only)

10 Reroute

10 Radiator

10 Wing

10 Splitter

25 Header

25 Intake 

     500

Seems like the only way to get the cam would be to claim JDM, or take laps (was what I was alluding to)

Edited by Wink

Share this post


Link to post
Share on other sites
1 hour ago, Wink said:

350 Base

40 Coils

20 Swaybar (front only)

10 Reroute

10 Radiator

10 Wing

10 Splitter

25 Header

25 Intake 

     500

Seems like the only way to get the cam would be to claim JDM, or take laps (was what I was alluding to)

https://champcar.org/tech/knowledgebase.php?article=40

 

5pts for reroute, or free if DIY.  

 

No airdam?

Share this post


Link to post
Share on other sites
1 hour ago, KoneKillah said:

And I won't say exactly what I'm thinking but this here got my gears turning.

 

image.png.a9c1eca4e678614eff6021f89480b1bb.png

I think about 30% of the public tech-desk questions are from me.  I will be documenting this and adding it our build page.  I will let you know how it goes at RA.

20191226_150734 (1).jpg

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

Hah it will be fun to play with this for sure. We will document everything on a build thread as well.

Edited by KoneKillah
出る釘は打たれる

Share this post


Link to post
Share on other sites
5 minutes ago, KoneKillah said:

Hah it will be fun to exploit this for sure. 

Good luck with that.   出る釘は打たれる

  • Like 2

Share this post


Link to post
Share on other sites

 

7 minutes ago, LuckyKid said:

Good luck with that.   出る釘は打たれる

 I appreciate that sentiment. new sticker for the car maybe? 

 

image.png

Edited by MichaelPal
  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...