Notices
Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by: KPower

Crank lightening, not knife edging

Old Apr 23, 2010 | 01:21 PM
  #21  
therieldeal's Avatar
Senior Member
iTrader: (2)
 
Joined: Oct 2007
Posts: 547
Total Cats: 2
From: Northeastern CT
Default

Originally Posted by Stealth97
Just get the cast SOHC protege crank, its like 10 or 11lbs lighter
beat me to it... they work fine for n/a applications and low boost. plenty strong enough.

sohc 1.8, 91.5-94 (don't want a small nose...)
Old Apr 23, 2010 | 01:34 PM
  #22  
NA6C-Guy's Avatar
Elite Member
iTrader: (1)
 
Joined: Feb 2008
Posts: 7,930
Total Cats: 44
From: Birmingham Alabama
Default

I just don't see it doing much. Enough to notice anyway. I'm with Jason on the flywheel comment.
Old Apr 23, 2010 | 01:38 PM
  #23  
sixshooter's Avatar
Moderator
iTrader: (12)
 
Joined: Nov 2008
Posts: 22,204
Total Cats: 3,560
From: Tampa, Florida
Default

Originally Posted by therieldeal
beat me to it... they work fine for n/a applications and low boost. plenty strong enough.

sohc 1.8, 91.5-94 (don't want a small nose...)
Even N/A I think I would greatly prefer our forged and nitrided crank.
Old Apr 23, 2010 | 09:35 PM
  #24  
Stealth97's Avatar
Elite Member
iTrader: (5)
 
Joined: Oct 2007
Posts: 2,156
Total Cats: 67
From: Canton, Ga
Default

I've been running the SOHC crank for three years now, had it balanced along with the rods, sees 8k RPM's on occasion, its super smooth. Half the counterweights make for less windage loss as well.
Old Apr 23, 2010 | 10:35 PM
  #25  
mazpr's Avatar
Senior Member
iTrader: (1)
 
Joined: Oct 2008
Posts: 531
Total Cats: -19
From: Trailer County
Default

Like other state, the more you leave the stock engine the better which they got their own magic.

Although many of you do not listen to this...

It is the same blcok of a competition Mazda 323 GTR pushing more than 300 HP, backj in PR who have done 10s the crank is stock...\\\\


IMO, leave it alone, the crank in stock trim is bullet proof.
Old Apr 24, 2010 | 12:03 AM
  #26  
railz's Avatar
Bannisheded
iTrader: (33)
 
Joined: Jan 2009
Posts: 1,056
Total Cats: -3
From: San Jose, CA
Default

Im next inline at Cardelli's for my 1.6 crank.

Are you doing this also Nick?
Old Apr 24, 2010 | 01:03 AM
  #27  
TURNS101's Avatar
Senior Member
iTrader: (10)
 
Joined: Oct 2005
Posts: 715
Total Cats: 5
Default

The loss in spool is due to some type of inertia situation I am not bright enough to explain. Mine had a **** ton taken off of it. 7 or lbs.

I saw no gains at all. It just looked cool and sounded smart. if budget is a worry, I would pass..
Old Apr 24, 2010 | 12:18 PM
  #28  
JasonC SBB's Avatar
Elite Member
 
Joined: Jul 2005
Posts: 6,420
Total Cats: 84
Default

Loss in spool is kind of a myth.
The car may show less boost at a given RPM in logs in say 1st, but car accelerates faster.
Old Apr 24, 2010 | 12:23 PM
  #29  
thesnowboarder's Avatar
Thread Starter
Elite Member
iTrader: (15)
 
Joined: Sep 2007
Posts: 2,034
Total Cats: 5
From: Incline Village, NV
Default

Originally Posted by railz
Im next inline at Cardelli's for my 1.6 crank.

Are you doing this also Nick?
No, my motor has been together for about 6 months or so.
Old Apr 24, 2010 | 12:33 PM
  #30  
miata2fast's Avatar
Elite Member
iTrader: (2)
 
Joined: Aug 2009
Posts: 3,145
Total Cats: 175
From: Dover, FL
Default

Originally Posted by JasonC SBB
Rebello in Northern CA?
Yes, out of CA. And I see I had the incorrect spelling. It is indeed Rebello. My bad.
Old Apr 24, 2010 | 02:43 PM
  #31  
Savington's Avatar
Former Vendor
iTrader: (31)
 
Joined: Nov 2006
Posts: 15,442
Total Cats: 2,106
From: Sunnyvale, CA
Default

Originally Posted by JasonC SBB
Loss in spool is kind of a myth.
The car may show less boost at a given RPM in logs in say 1st, but car accelerates faster.
It's a shame boost vs. RPM is so easy to log, since it's really not a good way of measuring anything. What you need to log is torque vs. time or RPM vs time.
Old Apr 25, 2010 | 12:41 PM
  #32  
Sparetire's Avatar
Elite Member
 
Joined: Dec 2008
Posts: 1,642
Total Cats: 36
From: Colorado
Default

Bingo. Load a dyno as if a Miata weighs 3500LBs and a 35R will spool like 2860 in terms of RPM.


The lighter crank means you are probbably spending less time in 1st, 2nd , etc gear, which will slow your spool a bit. Basically you have less time at a decent load state to spool the turbo. So chances are the perceived boost threshold will be higher, despite the car accelerating better.

From what I can see the weights are for driveability and NVH reduction more than for the engine itself, like the balance shafts you see in a lot of I-4s.
Old May 5, 2010 | 02:59 AM
  #33  
gnx7's Avatar
Newb
 
Joined: Apr 2010
Posts: 24
Total Cats: 0
From: San Francisco
Default

Rebello has been doing Datsun work for many many years and is one of the Bay Area's and maybe one of the nation's best 4/6 cyl machinists/engine builders.

They built a wicked n/a 2.4i setup for my friends 510 datsun that screamed.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Frank_and_Beans
Supercharger Discussion
13
Sep 12, 2016 08:17 PM
Greasyman
General Miata Chat
2
Sep 28, 2015 10:44 AM
Voltwings
Cars for sale/trade
0
Sep 27, 2015 06:40 PM
bahurd
Front Desk
0
Sep 21, 2015 08:45 AM


Thread Tools
Search this Thread

All times are GMT -4. The time now is 11:08 PM.