SaturnFans.com
what's new (beta) - classifieds - forums - photos


Go Back   SaturnFans.com Forums > Models > Saturn S-Series > S-Series Tech
Register FAQ Members List Groups Calendar Chat Room Search Today's Posts Mark Forums Read

Advanced Forum Search | Advanced Photo Search

Reply
 
Thread Tools Display Modes
Old 03-28-2012, 09:02 PM   #1
fixityourselfer
Member
fixityourselfer is on a distinguished road
 
Join Date: Nov 2010
Posts: 97
Default sc2 engine intake bore (small) sc1 intake bore (large) why??

the holes going into the engine on the intake side seem like really big square holes.

the holes on the sc2 engine are really small. roundish and smaller then on the sc1 sohc engine.

whats up with that??

I got to look at my dohc intake holes when I took the manifold off, and I was surprised to see that the intake manifold gaskets that go on the sc1 sohc engines have way bigger holes for the air to go into the engine.

thats wierd, no?
bigger holes means MORE power, and yet the dohc sc2 engine has SMALLER HOLES!!

can anyone explain that?

REWARD EXCELLENCE!

Add to fixityourselfer's Reputation
Rate the quality of this post and help fixityourselfer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fixityourselfer is offline   Reply With Quote
SaturnFans.com Sponsored Links
Old 03-28-2012, 10:31 PM   #2
madpogue
Super Member
madpogue is a splendid one to beholdmadpogue is a splendid one to beholdmadpogue is a splendid one to beholdmadpogue is a splendid one to beholdmadpogue is a splendid one to beholdmadpogue is a splendid one to beholdmadpogue is a splendid one to behold
 
Join Date: Sep 2004
Location: Madison, WI USA
Posts: 25,031
 

1996 SW2
Default Re: sc2 engine intake bore (small) sc1 intake bore (large) why??

Are you talking about the intake PORTS between the intake manifold and cylinder head? You do realize there are TWO for each cylinder on the DOHC, and ONE on the SOHC, right?

REWARD EXCELLENCE!

Add to madpogue's Reputation
Rate the quality of this post and help madpogue reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
madpogue is offline   Reply With Quote
Old 03-28-2012, 10:39 PM   #3
PlasticCarsRock
Master Member
PlasticCarsRock is a jewel in the roughPlasticCarsRock is a jewel in the roughPlasticCarsRock is a jewel in the rough
 
PlasticCarsRock's Avatar
 
Join Date: Dec 2005
Location: Brookline, MA
Posts: 4,288
 

1995 SL2
Default Re: sc2 engine intake bore (small) sc1 intake bore (large) why??

With twice as many cams and valves, the head is much more complex with regards to cooling and lubricating. There isn't as much spare room in the DOHC head to allow for larger ports.

Even with the smaller ports, Saturn was able to achieve the extra power they wanted. Given the complete lack of any performance oriented re-designs throughout the lifespan of the S-Series, it's obvious that Saturn had no desire to increase the power beyond 124 hp.

The port design (size and sharp angle) is one of the biggest problems with the engine when it comes to trying to make any significant power (without boost).

Also, smaller ports actually help with low-end torque (because of the increased velocity of the air). It isn't until the higher rpms that the restriction becomes a problem. If you enlarge the ports much (such as gasket-matching), it is typical to notice a decrease in low end power, but the increase in the top end makes it worthwhile for most people.

Quote:
Originally Posted by madpogue View Post
Are you talking about the intake PORTS between the intake manifold and cylinder head? You do realize there are TWO for each cylinder on the DOHC, and ONE on the SOHC, right?
There's still only one port where the manifold meets the head--it splits into two right there, though. I've never seen a bare SOHC head, but I have seen the gasket for one, and I believe that the ports where the manifold meets the head are, in fact, much larger (and square). In other words the SOHC ports are larger than both DOHC ports combined. The SOHC ports obviously must get much smaller as they near the valves, though, and the change in port size is not such a good thing (better than smaller but even ports the whole way, perhaps, but not much better).

...
High compression build: .033" shaved/ported head, flat-faced valves; gen3 rods, pistons, tie-plate; OE header, custom CAI, SDA street cams with adjustable sprockets, WBO2, SAFCII, LSD. ASE A1-A8+L1

Last edited by PlasticCarsRock; 03-28-2012 at 10:45 PM..

REWARD EXCELLENCE!

Add to PlasticCarsRock's Reputation
Rate the quality of this post and help PlasticCarsRock reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
PlasticCarsRock is offline   Reply With Quote
Old 03-29-2012, 01:01 AM   #4
td1238
Senior Member
td1238 will become famous soon enoughtd1238 will become famous soon enough
 
Join Date: Mar 2010
Location: Milwaukee
Posts: 1,999

1999 SL2
Default Re: sc2 engine intake bore (small) sc1 intake bore (large) why??

Part of the trick is fuel vaporization. Long, narrow intake runners also achieve this. They create high vacuum, which aids in fuel vaporization, much velocity, which stirs up the fuel, and a long runner for the fuel to vaporize in (assuming that the runner is hot). The last benefit doesn't apply so much to MPFI engines, where the fuel is injected right at the intake valve. It applies more to TBFI and carbureted engines.

The long and/or narrow intake runners of course restrict WOT airflow, and reduce power here, but they make for great low-end power and efficiency.

Some high-end designs call for variable length intake runners, or switching between runners of different shapes and sizes.

REWARD EXCELLENCE!

Add to td1238's Reputation
Rate the quality of this post and help td1238 reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
td1238 is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Big Bore TB 2006 ion2 Ion Mods 8 02-10-2009 08:00 AM
bore tb ect. 9sL26 S-Series Mods 4 03-06-2007 09:46 AM
WTB: Big Bore TB M1snowman Classifieds 2 06-05-2005 10:55 PM
bore anti honda Mods and Performance 3 01-31-2004 06:56 AM
To bore or not to bore Son93SL2 Miscellaneous Tech 2 05-21-2001 06:55 AM


All times are GMT -5. The time now is 05:14 AM.

Advanced Forum Search | Advanced Photo Search


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SaturnFans.com. The Saturn Enthusiasts Site.