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Originally Posted by Shadow24v
Assuming i can run the S5 internals and intake, is it necessary to upgrade the injectors or is there enough leeway in the stock fueling system to accommodate the HP bump?
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I made 216 WHP @ 7500 rpm running 63% Duty cycle on stock 460 cc/min injectors.
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Originally Posted by Shadow24v
Speaking of rebuilding. i have Atkins rebuild video but its not really that in depth. has anyone watched mazdatrix's rebuild and porting DVDs? are they worth it for a new rotorhead doing their first rebuild?
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Porting is simple - and yet so complicated.
Short Story = It depends if you are the kind of person that learns well from watching a video.
Long Story = I am a hands-on person, always have been. I learned about porting by having a rotary engine apart and discussing what effect each cut would have on performance with several experienced rotary tuners. The fundamentals are very simple.
The simplest approach that I can give you is a list of rules of thumb:
1 -> To determine desired port opening/closing angles, go to CompCams website and find a Hp/Torque curve that you like and then duplicate the valve opening/closing times with your rotary's ports.
2 -> Make the port close as abruptly as possible. Although some argue that this harms side seal life, I have not seen this.
3 -> Understand your engine - You will not get good port velocity at 1,000 rpm. Don't try to cut low-rpm-tuned ports into your housings.
4 -> Get the air in - A good intake/throttle will make as much or more power than a port job. Uniform cross-sectional area from plenum to port is a big plus for power
5 -> Get the air out - A good port-matched exhaust (Short-tube, collected headers) will help your power more than you expect.
Here is porting in a nutshell:
You can't go more than about 1/16th of an inch towards the center (you will hit the oil seal).
You can't go out much at all (side seal will have no support and will dig in).
You can't go down because it is barely ever open and is too narrow to get air too.
Up is all you have for a street port.
Unfortunately, it is impossible to get an early enough port opening for any appreciable port overlap (intake and exhaust open simultaneously) so for "Hot" cam equivalents, you will need a bridge port.
A bridge port leaves a "bridge" for the side seal to travel on, while opening up a whole new world of early intake opening and port overlap.
This is a crude illustration that I made. I am sure that better ones exist (It wouldn't take much) but the content is there.
