TeamSwift

Home of the Suzuki mini-compacts ! Your Home for all things Suzuki Swift, Geo Metro, Holden Barina, Chevy Sprint, Pontiac Firefly, and Suzuki Cultus. TeamSwift is a technical performance oriented community!
It is currently Fri Oct 20, 2017 3:29 pm

Underbody braces, turbos and more!

All times are UTC - 5 hours




Post new topic Reply to topic  [ 6 posts ] 
Author Message
PostPosted: Tue Jul 03, 2012 4:18 am 
Offline
Senior Member
User avatar

Joined: Thu Feb 12, 2004 11:30 pm
Posts: 1706
Location: Rivendell
So, after getting an MLS head gasket, I was trying to figure out how much of a drop in compression this would have on my engine. I chanced upon the following compression calculator

http://www.csgnetwork.com/compcalc.html

I was astounded at how a very small change in the figures made a marked impact on the compression ratio.

f'rinstance, a standard head gasket is .3 mm thick, the MLS is .5 mm
The head gasket bore size of a standard head gasket is 76.5mm, the MLS is 75.3mm

just this difference dropped compression from 11:1 down to 10.68:1
So, to make up the difference, I'll have to shave 7 thou off the head.

Question to anyone with pistons in the hole. what is the piston deck clearance at tdc? Since I totally ripped my engine down, I do not have the liberty to measure this. It would be nice to know how far I can go before I get into interference issues. The guys at the engine reconditioner were talking zero deck clearance for high performance engines.
DOHC G13B (cultus)
Help?

_________________
Understeer is when you hit the wall with the front of the car and oversteer is when you hit the wall with the rear of the car.HP is how fast you hit the wall, torque is how much you push the wall out.


Top
 Profile  
 
PostPosted: Tue Jul 03, 2012 4:33 am 
Offline
Moderator
Moderator
User avatar

Joined: Sun Feb 23, 2003 4:16 am
Posts: 8033
Location: Ontario, Canada
I think it is zero on a DOHC motor. I've never seen a .3 mm head gasket. Every one I've seen on GT motor is 1 mm thick.

_________________
Contact 3tech: g10pro@rocketmail.com


Top
 Profile  
 
PostPosted: Tue Jul 03, 2012 5:02 pm 
Offline
Senior Member
User avatar

Joined: Thu Feb 12, 2004 11:30 pm
Posts: 1706
Location: Rivendell
Hmmm
<gets out calipers...> dammit, at work, will have to wait... mebbe 1.3??? I know there was .2 difference...

_________________
Understeer is when you hit the wall with the front of the car and oversteer is when you hit the wall with the rear of the car.HP is how fast you hit the wall, torque is how much you push the wall out.


Top
 Profile  
 
PostPosted: Wed Jul 04, 2012 12:03 am 
Offline
Senior Member
User avatar

Joined: Thu Feb 12, 2004 11:30 pm
Posts: 1706
Location: Rivendell
ellpee wrote:
Hmmm
<gets out calipers...> dammit, at work, will have to wait... mebbe 1.3??? I know there was .2 difference...

Mike3 was right standard gasket was 1.3, MLS was 1.5mm

so the boys have taken 3 thou. off the deck. its a compromise.

_________________
Understeer is when you hit the wall with the front of the car and oversteer is when you hit the wall with the rear of the car.HP is how fast you hit the wall, torque is how much you push the wall out.


Top
 Profile  
 
PostPosted: Mon Jul 09, 2012 4:10 pm 
Offline

Joined: Sat Nov 15, 2008 7:47 pm
Posts: 1292
Location: Trinidad, W.I.
0.003" is barely anything...you'd probably get that off by just passing some sandpaper on it using a straight edge! :P

_________________
~the other Ralph~
Certified Suzuki Owner:
MKIII Swift GTi - The Green Destiny!
2010 Suzuki Jimny - The DD Workhorse!


Top
 Profile  
 
PostPosted: Mon Jul 09, 2012 7:43 pm 
Offline
Senior Member
User avatar

Joined: Thu Feb 12, 2004 11:30 pm
Posts: 1706
Location: Rivendell
The compromise was that I had already "passed the sandpaper..." (sheet of glass, valve grinding paste and elbow grease for two hours) to see if I could straighten the kinks out. I will have to see how the pistons are sitting once I get it back.... then calculate exactly how much complression has been lost. I am hoping to get back to a shade under 11:1.
In saying that, it is just a raw calculation. I am unsure exactly how accurate you can analyse true compression even using volumetric displacemenrt with a pipette etc. such a small change in any dimension has quite a marked impact.

_________________
Understeer is when you hit the wall with the front of the car and oversteer is when you hit the wall with the rear of the car.HP is how fast you hit the wall, torque is how much you push the wall out.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group