General Miata Chat A place to talk about anything Miata

Come along on my journey for a destroked 1.7L Miata

Thread Tools
 
Search this Thread
 
Old 10-20-2021, 03:09 AM
  #1  
Newb
Thread Starter
 
TowerCrisis's Avatar
 
Join Date: Jan 2021
Location: San Mateo, CA
Posts: 35
Total Cats: -35
Default Come along on my journey for a destroked 1.7L Miata

Heya folks!

Call me foolish but I'm starting a long-term project to make a wild setup.
  • BP8 block bored and sleeved to 85.5mm
  • Billet crank with 75mm stroke (1.722L)
  • 1.97 rod ratio (shortened pistons & longer rods)
  • Custom cam profile
  • & of course a host of supporting mods
Should be able to turn 10,500 RPM, with a mean piston speed of 26.1m/s with a peak of 40.5m/s and peak acceleration of 56829m/s/s at TDC.

Working on quotes for all this right now. Budget = yes. First order of business after verifying I can get all of this is ordering the billet crankshaft and sleeved block.



(I also have the data for a stock BP8 at 7500, not pictured)


Why you ask? Because I want to hear this thing scream.
TowerCrisis is offline  
Old 10-20-2021, 12:48 PM
  #2  
Soy
Newb
 
Soy's Avatar
 
Join Date: Apr 2019
Posts: 29
Total Cats: 27
Default

I applaud your aspirations but i have to ask. Why not just buy a k20 and swap it if you want a high revving 4 cylinder? If you have the budget for this you have the budget for a screamer all motor k20.

Last edited by Soy; 10-20-2021 at 01:53 PM.
Soy is offline  
Old 10-20-2021, 01:03 PM
  #3  
Senior Member
 
msmola2002's Avatar
 
Join Date: Aug 2017
Location: Norwich NY
Posts: 635
Total Cats: 322
Default

Can a BP head flow the volume needed for 10.5Krpm of air?
msmola2002 is offline  
Old 10-20-2021, 01:57 PM
  #4  
Newb
Thread Starter
 
TowerCrisis's Avatar
 
Join Date: Jan 2021
Location: San Mateo, CA
Posts: 35
Total Cats: -35
Default

Originally Posted by Soy
Why not just buy a k20 and swap it if you want a high revving 4 cylinder?
It simply comes down to me being passionate about the BP8. I really like it as a platform and want to push the limits.

Originally Posted by msmola2002
Can a BP head flow the volume needed for 10.5Krpm of air?
It's roughly ~33% higher flow at redline. That shouldn't be an issue with porting and FI. But we'll see!
TowerCrisis is offline  
Old 10-21-2021, 06:49 AM
  #5  
Senior Member
 
rwyatt365's Avatar
 
Join Date: Dec 2007
Location: ATL
Posts: 1,350
Total Cats: 128
Default

Originally Posted by TowerCrisis
It simply comes down to me being passionate about the BP8. I really like it as a platform and want to push the limits.
I appreciate your passion. Looking forward to your updates.
rwyatt365 is offline  
Old 10-21-2021, 08:57 PM
  #6  
Junior Member
 
cpierr03's Avatar
 
Join Date: Mar 2015
Posts: 287
Total Cats: 33
Default

Sounds wild. You used math so I assume you know what you're doing.

The BP is a weird engine to be enthusiastic about, but more power to you (literally!).

In for the results, hope it works out.
cpierr03 is offline  
Old 10-22-2021, 02:14 PM
  #7  
Newb
 
DickieRSLTD's Avatar
 
Join Date: Oct 2021
Posts: 1
Total Cats: 1
Default Short stroke crank in the UK

Hi folks
I am embarking on a similar journey in the UK,
I had a quote 18 months ago for a custom crank, short stroke !
I will be using 85mm pistons in a BP4W block I want to build a high reving motor with 1796 cc for a roadgoing sprint and hillclimb car.
My local class is 1400cc to 1800cc then 1800cc to 2800cc
I already have some of the parts I need. I will be collecting a donor engine in the next couple of weeks.
This is for an ITB build !!!
I am already at 169 BHP with a stock BP4W block and mild diy head work + cams. aftermarket ecu and bike throttle bodies.
Tuned at https://enginetuner.co.uk/

Last edited by DickieRSLTD; 10-22-2021 at 02:28 PM. Reason: more info
DickieRSLTD is offline  
Old 10-23-2021, 06:05 AM
  #8  
Junior Member
 
allofit's Avatar
 
Join Date: Nov 2020
Location: Greatest Britain
Posts: 103
Total Cats: 23
Default

This is awesome. Both @TowerCrisis and @DickieRSLTD!

Looking forward to your progress and results.

allofit is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
mr2nique
Engine Performance
2
08-23-2021 02:44 AM
BogusSVO
Engine Performance
0
04-03-2012 10:25 AM
Erotomania
Engine Performance
6
05-13-2010 10:21 AM
rogezeus2003
Engine Performance
25
01-11-2010 02:21 PM
ls1motorsports
Engine Performance
9
09-09-2009 11:00 PM



Quick Reply: Come along on my journey for a destroked 1.7L Miata



All times are GMT -4. The time now is 09:59 AM.