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Old 10-26-2008, 07:56 PM   #1
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Default manifold length standards?

Rctech and Google have gotten me nowhere on this one

Is there an industry standard for measuring manifold length? I understand to use a cloth measuring tape and follow the centerline of the manifold but where do you start and end? My best guess is from the very end by the engine to the very beginning of the flange down by the pipe since that part overlaps? A photoshopped pic with a start and end line indicating where to measure would be great if you have the knowledge and 10 minutes for me! I've also measured end to end and got 100mm because I wanted whatever I own to be a long manifold. Current RB manifolds are 92mm for short and 98mm for long. I can picture measuring what I have about 4 different ways to get between 89 and 100mm! What are other manufacturers claiming for short and long dimesions? Not finding any other brands that list a length. They just say short or long. Because they are just designed with their own pipe as a system??

I know I have a REX 9886 pipe and matching manifold but is it long or short? It's starting to bug me thinking about getting a new engine for next year.
And where can I find some history on REX? I have no idea who they were/are and want to know about the quality of this pipe. I got it used on a roller. The RB engines (I'm getting an S5) don't seem to take too well to OFNA's 9886 from what I have read.

Educate me please
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Old 10-26-2008, 08:24 PM   #2
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Really simple, longer manifolds=more bottom end, shorter manifolds=more topend. Round parabolic header= smooth power delivery, square headers= offer more raw torque will less control in general. The numbers on the pipe are the same design between the brands. As for headers, there is no standard as to how they measure and determine their lengths, but knowing the numbers within the brand lets you know what type powerband you'll get.

REX motors are from Novarossi. Same as TOP. They were all offered with the same internal workings, but some may have an alteration to someone elses standard or was distributed under a said name to certain distributors or importers. As for now, the names have been switched to represent the purpose design the engine are designed for. That being car, marine and airplane/Heli use.
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Old 10-27-2008, 03:27 AM   #3
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Thanks. That is helpful to me but then also I guess I'll never figure out if I've got the short or long manifold then. I'll just have to try it and see. If anyone out there still has a old REX combo and knows what they've got (short or long), maybe you can give me the measurements!
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Old 10-28-2008, 10:01 AM   #4
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ezveedub
That turned out to be a lot of help. Novarossi still makes the 9886 and I found enough pics on the current 41001, 41005,41019, 41020, 41021 manifolds to figure out I am 95% sure I have the 41005 which is long - which is what I wanted to start with ! I can open the pics and zoom in and out until the size matches my actual manifold to hold up to the computer monitor
I would be 100% sure if I could find all of the pics taken straight from the side. Most pics are at an angle and hard to compare. If I feel I need a low end boost I'll just try the 11mm spacer (21111) with the long coupler springs (63200) and see what that does later.
Thanks! I can move on and and get the pipe all cleaned out and ready for the new engine with some confidence
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Old 10-28-2008, 03:47 PM   #5
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If you want to see some headers and pipes pics, go the link below.

http://www.jpracing.com/en/products/...usts_fx21b.php
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Old 10-29-2008, 03:30 AM   #6
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Quote:
Originally Posted by ezveedub View Post
If you want to see some headers and pipes pics, go the link below.

http://www.jpracing.com/en/products/...usts_fx21b.php
That is a very cool presentation. I noticed that the short Novarossi is much shorter than a short standard jpracing though. It must vary some by brand what is considered short or long based on the pipe design. Still gives you a really good idea though. Thanks again for the help.
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