Ordered my Ott X-pipe today!
09-19-2004, 02:45 PM
#16
Not sure you can add high flow cats to the standard Ott x....this would put them too far back to be effective. Adam B has a custom made Ott X with high flow cats (crafted by the master himself) and the X is moved forward a bit to accommodate the cats and allow them to come up to temp. I suppose you can try to add the cats...let us know if it works out.....
Later,
Tom
midlman@rennlist.net
89GT mit x crossover ;-)
Later,
Tom
midlman@rennlist.net
89GT mit x crossover ;-)
09-19-2004, 03:18 PM
#18
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Originally Posted by Thaddeus
Louis himself has done it, he recommended the cats I should buy. I'll be asking for his advice on how to implement them...
" Adam B has a custom made Ott X with high flow cats (crafted by the master himself) "
09-19-2004, 07:07 PM
#21
Hey Pappy,
How do you know they work? They do look a ways back. Interesting adding the air injection way up front. Typically it is added mid to rear in the cat section to aid in keeping temps up and finish the reaction. But hey if you have some good numbers (I should say better than without cats as most 928s in a good state of tune run clean without cats) then I may do the same..just to tone down the noise level...Im currently running with the x into a stock GT small mid resonators and out a rmb..loud to say the least...
Later,
Tom
midlman@rennlist.net\
89GT
How do you know they work? They do look a ways back. Interesting adding the air injection way up front. Typically it is added mid to rear in the cat section to aid in keeping temps up and finish the reaction. But hey if you have some good numbers (I should say better than without cats as most 928s in a good state of tune run clean without cats) then I may do the same..just to tone down the noise level...Im currently running with the x into a stock GT small mid resonators and out a rmb..loud to say the least...
Later,
Tom
midlman@rennlist.net\
89GT
09-19-2004, 07:59 PM
#22
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Hello Tom,
The picture is not of my car. This picture is of Ron Gottshalk's GT. He is at 928 International and he can probably tell you what his emissions numbers are. I have not done my exhaust yet but plan to go the same route. With CATs I am expecting the same increase as Ron, about +30 rwhp, because I have GT cams and other mods. I also plan to use the Bullet mufflers, P/N 212161, because they fit, flow well, and sound very good. To get more power the pipe size must increase. The stock pipes will limit how much power you can make. Louie recommends 2.5". I trust that Louie and Ron have done their homework.
The picture is not of my car. This picture is of Ron Gottshalk's GT. He is at 928 International and he can probably tell you what his emissions numbers are. I have not done my exhaust yet but plan to go the same route. With CATs I am expecting the same increase as Ron, about +30 rwhp, because I have GT cams and other mods. I also plan to use the Bullet mufflers, P/N 212161, because they fit, flow well, and sound very good. To get more power the pipe size must increase. The stock pipes will limit how much power you can make. Louie recommends 2.5". I trust that Louie and Ron have done their homework.
09-19-2004, 08:26 PM
#24
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Hello Jim,
Ron did dyno his car but you would have to ask him for the charts. I'm not sure if he participates on this forum.
Their are some 90 GT numbers posted on The Ott WEB site which show the GT before and after;
http://www.performance928.com/cgi-bi...ss_parent=1125
The CATs rob you of 6 to 10 HP depending on their flow rate. This makes sense because without CATs the GT is making +36 rwhp. With CATs expect about +28 ~ +29 rwhp.
I am asking Kevin Carr to build my exhaust. He likes to do single pipe 928s but I can convince him to go dual pipe stainless for a price;
http://www.carrtec.com/
Ron did dyno his car but you would have to ask him for the charts. I'm not sure if he participates on this forum.
Their are some 90 GT numbers posted on The Ott WEB site which show the GT before and after;
http://www.performance928.com/cgi-bi...ss_parent=1125
The CATs rob you of 6 to 10 HP depending on their flow rate. This makes sense because without CATs the GT is making +36 rwhp. With CATs expect about +28 ~ +29 rwhp.
I am asking Kevin Carr to build my exhaust. He likes to do single pipe 928s but I can convince him to go dual pipe stainless for a price;
http://www.carrtec.com/
09-19-2004, 08:40 PM
#25
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Could be more than the exhaust at work here with the tuning happening at the same time. Also the 'Tom' in that post is the guy who owns the dyno shop.
Upper line is after tuning ignition timing and fuel mixture plus changing stock cats to 2.5" X pipe with 2.5" dual Bullet brand mufflers and 2.5" dual rear exhaust pipes
Upper line is after tuning ignition timing and fuel mixture plus changing stock cats to 2.5" X pipe with 2.5" dual Bullet brand mufflers and 2.5" dual rear exhaust pipes
Originally Posted by pappy92651
Hello Jim,
Tom Middleton posted some numbers on The Ott WEB site which show his GT before and
The CATs rob you of 6 to 10 HP depending on their flow rate. This makes sense because without CATs Tom is making +36 rwhp. With CATs expect about +28 ~ +29 rwhp.
/[/url]
Tom Middleton posted some numbers on The Ott WEB site which show his GT before and
The CATs rob you of 6 to 10 HP depending on their flow rate. This makes sense because without CATs Tom is making +36 rwhp. With CATs expect about +28 ~ +29 rwhp.
/[/url]
09-19-2004, 09:21 PM
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Right, I don't think that you get any noticeable gains without changing fuel and timing maps to fit the mods. Since you are moving more air, fuel must be compensated to keep the AFR within range. I found out the hard way when I burned custom chips for my car, eliminated the mufflers, big intake valves, installed GT cams, etc. I had to increase my fuel pressure just to get the car to run sort of OK. It took another few weeks to get the power band I wanted.
I'm not playing with fuel pressure regulators anymore. That will change if I make big changes to the engine. Instead I'm creating custom maps that go into a computer. This allows me to accommodate certain mods without doing mechanical fuel adjustments. I can change my ignition timing to suite fuel, cam timing, exhaust, and intake. More on this later.
Lets just say that there is more required than just opening up the exhaust.
I'm not playing with fuel pressure regulators anymore. That will change if I make big changes to the engine. Instead I'm creating custom maps that go into a computer. This allows me to accommodate certain mods without doing mechanical fuel adjustments. I can change my ignition timing to suite fuel, cam timing, exhaust, and intake. More on this later.
Lets just say that there is more required than just opening up the exhaust.
