Notices
CEN Racing This forum is to discuss all CEN Racing products.

GST 7.7 exhaust

Old 01-18-2007, 10:42 AM
  #1  
MONAROMAN
Senior Member
Thread Starter
 
Join Date: Jan 2007
Location: Sydney, AUSTRALIA
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Default GST 7.7 exhaust

I have just recently bought a GST and was wondering what other owners are running for an exhaust setup, any good pipes for the .46 engine, has anyone found or fitted a better header than the stock one.
Old 01-18-2007, 07:42 PM
  #2  
.46NitroAddict
Senior Member
 
Join Date: Mar 2006
Location: DevonportTasmania, AUSTRALIA
Posts: 143
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust

Hi MONAROMAN,

Love your Tag, I'm an SS man my self, & would love to add a monaro to the shed, but ......

Anyway, back to your exhaust. Try unscrewing the alum. muffler in the center & take out the restricters, & see what you think.

If your happy with the change, you can also look in the Engine pipe, on my Gen LE where it goes on to the gasket at the motor, in the 90Deg bend there is also a restriction, you can carefully whittle it away, to open up exhaust flow.

See what you think,

.46NitroAddict [>:]
Old 01-18-2007, 07:59 PM
  #3  
The Real Dogman
 
The Real Dogman's Avatar
 
Join Date: May 2006
Location: Pontiac, MI
Posts: 2,256
Likes: 0
Received 2 Likes on 2 Posts
Default RE: GST 7.7 exhaust

Monaroman, I have built an exhaust I want to perfect. It Created very good flow both on bottom and top end. I have not Flow tested it on a flow bench but the extra power and sound is fantastic. I am not using it now because I am testing other things but here are acouple pictures of it for your reference. Just remember this is a prototype..
Attached Thumbnails Click image for larger version

Name:	Sq45656.jpg
Views:	15
Size:	72.5 KB
ID:	601126   Click image for larger version

Name:	Av69093.jpg
Views:	19
Size:	54.2 KB
ID:	601127   Click image for larger version

Name:	Hm23259.jpg
Views:	15
Size:	63.2 KB
ID:	601128   Click image for larger version

Name:	Vp40159.jpg
Views:	13
Size:	60.1 KB
ID:	601129  
Old 01-19-2007, 05:03 AM
  #4  
MONAROMAN
Senior Member
Thread Starter
 
Join Date: Jan 2007
Location: Sydney, AUSTRALIA
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust

Hey 46 nitro, went in to buy an ss, walked out a monaro owner, didn't think I could afford it ( I probably shouldn't have) but I've had company cars for 10 years so I think I deserved it... its my baby, still stock except for some 20's. Thanks for the heads up un the baffle, I'll give it a shot and see what I think along with the header, if I don't like it I may go down the avenue that dogman has, I'm a fridgy and the copper pipe looks easy to whip up. Hey dogman, that pipe's only single chamber is it? Completely hollow inside? Have you experimented with any other designs?
Old 01-19-2007, 05:20 AM
  #5  
whitaker44
Junior Member
 
Join Date: Jan 2007
Location: Oceanside, CA
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust

by takeing out th restriction baffle with it hurt performance?? i know that 2 strokes make the power in the pipe. i took out the baffles in my yamaha r1 and it made a world of difference on a 4stroke. same concept? but then again 2 stroke dirt bikes have no restictors in the power pipe
Old 01-19-2007, 06:09 AM
  #6  
MONAROMAN
Senior Member
Thread Starter
 
Join Date: Jan 2007
Location: Sydney, AUSTRALIA
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust

Yeah I thought the baffled acted to direct exhaust pulses with unburnt fuel back into the open exhaust valve for motor cooling - but from research everyone seems to have adifferent idea on if its bad to remove them or not, I think at minimum you'd have to retune your engine because the back pressure would change, but this would be the same with most pipe changes I'd imagine, might pay to keep an eye on motor temp
Old 01-19-2007, 06:48 AM
  #7  
The Real Dogman
 
The Real Dogman's Avatar
 
Join Date: May 2006
Location: Pontiac, MI
Posts: 2,256
Likes: 0
Received 2 Likes on 2 Posts
Default RE: GST 7.7 exhaust

Monaroman no its NOT a a single chamber there are three chambers via baffle plates on both ends @ the caps. The baffle plates have five 3/16" holes drilled in a star pattern, and the holes have a sligt flaring to the outlet side to promote flow without hurting back pressure. The plates also have 1 oil drain notch ground into the bottom edge only about 1/16" notch is required. I have experimented with two other designs such as a single outlet but this one seems to work the best. I have also played around with different mounting...
Old 01-19-2007, 07:11 AM
  #8  
MONAROMAN
Senior Member
Thread Starter
 
Join Date: Jan 2007
Location: Sydney, AUSTRALIA
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust

NICE! Approximately how large are the outer chambers in length compared to the inner? Did you solder the baffles internally to the main pipe? Are the baffles flat apart from the flared holes? Is that 5/8" pipe for the inlet pipe and 2 x 3/8" stingers? Main pipe 1 & 3/8"? Sorry for the questions but I think I might give it a crack, maybe make up two or three at once, each slightly different
Old 01-19-2007, 07:45 AM
  #9  
The Real Dogman
 
The Real Dogman's Avatar
 
Join Date: May 2006
Location: Pontiac, MI
Posts: 2,256
Likes: 0
Received 2 Likes on 2 Posts
Default RE: GST 7.7 exhaust

The plates are soldered to 3/4" interal pipe couplers that are about 1/2" long equally slid into the "T" and the end caps so the outer chambers are approx 1 1/8" and the inner(main) chamber is about 2" long. 1 version has 5/8" inlet and header pipe and the other has 1/2" inlets with 1/2" header. The stingers are 3/8" on version and another version has 3/8" stingers and washers with 1/4" holes soldered in them to tune them.

Hope you attempt this, if you are going to build your own header, remember to use silver solder. the exhaust temps are hotter than normal solder and will blow the pipes apart!! Sounds cool tho.


have fun
Old 01-19-2007, 08:03 AM
  #10  
MONAROMAN
Senior Member
Thread Starter
 
Join Date: Jan 2007
Location: Sydney, AUSTRALIA
Posts: 272
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust

Yeah I think I'll give it a go, thanks for the info, just got to start getting the fittings together and a bit of a plan. Next job I do at work will have a few elbows and endcaps go missing
Old 01-19-2007, 08:42 AM
  #11  
.46NitroAddict
Senior Member
 
Join Date: Mar 2006
Location: DevonportTasmania, AUSTRALIA
Posts: 143
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust


ORIGINAL: MONAROMAN

Hey 46 nitro, went in to buy an ss, walked out a monaro owner, didn't think I could afford it ( I probably shouldn't have) but I've had company cars for 10 years so I think I deserved it... its my baby, still stock except for some 20's. Thanks for the heads up un the baffle, I'll give it a shot and see what I think along with the header,
Hi Monaroman, 20's nice! I wanted a monaro, but I have kids, & the missus uses it as a daily driver - so a compromise was made - SS. Anyway, back to the exhaust, I'm keen to see how it goes for you with your GST.

A mate of mine has a Genesis LE, like me, & from the tests we have done between the two (his exhaust modded, mine std) it appears that in std trim the restrictors help with low down power. Where as the modded exhaust seems to have more up in the mid & upper rev range. (both running the same glow plugs & fuel). Yes, you will have to retune. I guess it depends on what you are doing & your driving style, but the restrictors are a quick & easy thing to try at no cost - if you don't like you can always put them back in.

Hope this helps,
.46NitroAddict [>:]
Old 01-22-2007, 08:35 AM
  #12  
.46NitroAddict
Senior Member
 
Join Date: Mar 2006
Location: DevonportTasmania, AUSTRALIA
Posts: 143
Likes: 0
Received 0 Likes on 0 Posts
Default RE: GST 7.7 exhaust


ORIGINAL: .46NitroAddict
A mate of mine has a Genesis LE, like me, & from the tests we have done between the two (his exhaust modded, mine std) it appears that in std trim the restrictors help with low down power. Where as the modded exhaust seems to have more up in the mid & upper rev range. (both running the same glow plugs & fuel). Yes, you will have to retune. I guess it depends on what you are doing & your driving style, but the restrictors are a quick & easy thing to try at no cost - if you don't like you can always put them back in.

Further to this topic, have you read this review by RCU on the GST7.7? http://www.rcuniverse.com/forum/announcement.asp?id=225
it also confirms what I spoke of above, regarding increased performance, when dropping the exhaust restrictors.

Regards, .46NitroAddict [>:]

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.