13BTNOS

I've searched and haven't really found anything of significance on this subject. What I would like is to see is some examples of what people are doing port wise on their exhaust this would be for turbo application and engines that are strictly race engines. Don't give the answer like as big as you can I'd like to know more like how many mm up from stock, how many mm down from stock, how wide you go with your ports, do you keep the inserts in or take them out, questions like those would like to be answered. Simply I would like to compare what I do with my ports to what others do and see if I can learn something from others I'm always up for learning. I've got a saying " If you have a better way to f_ck the monkey, then hey show me how to f_ck it". Any info would be appreciated. Thank you.

z8cw

So how do u f'ck your monkey. Would be nice to see your ports on this forum. Here is apic I collected on this forum earlier. Popular port in Japan for road racing application.



[attachment=26146:attachment]

13BTNOS

I don't have pictures but I can give a detailed description. On 13b housings I keep 15mm side clearance on the port, meaning I mark 15mm from each side of the exhaust port so total width of the port is 50mm. I don't like to go too wide because I like to have a lot of support for the apex seal. On the top of the port 3mm max from stock is what I do. I cut it in a slight arc and not straight across. Bottom of the port depending on what I do to the intake and what type of fuel will be ran can vary from 5mm down from stock up to 15mm down from stock. When porting is done I put a 2mm bevel around the port just like the stock ports. I keep the steel inserts in and open them up slightly but don't make them too thin and I polish the hell out of the port and sleeve. That's another thing I have a question on is it possible to remove the steel insert for a turbo application mind you it would be for a race car - drag racing? My current project right now is a 13BREW half bridged only the ends, and they are small bridges they don't go past the water seals and the opening starts half way up the the port, trying to keeping overlap to a minimum, this with a Precision PT74GTS turbo and running Microtech ltx12s and LS1 80mm throttlebody adated to a stock UIM. That said would it be OK to take the steel sleeve out of the exhaust? Any input will help. Thank you. Oh yeah check out this link http://www.raycar.freeservers.com/photo5.html this is my friends car it's his old setup which I now have and this was about 3years ago he has since moved on to bigger and better but my setup will be basically the same. Same engine combo, different turbo and engine management, but in the same chassis a Datsun B110 1200.

fdracer

yeah, you can punch out the sleeves and make the exhaust port huge. but that'll defeat your purpose of keeping overlap to a min. plus your intake might not flow enough to fully utilize the big ex. ports.

13BTNOS

How does the bare aluminum fare with the heat from a turbo motor? I've read of some people ceramic coating the inside of the exhaust port after removing the sleeve. And also if you are or know of someone who has such a setup with the sleeve removed how aggressive/big are the ports. With a big bridge port N/A motor you are not worried about overlap so you can go pretty big on them but with a turbo how does it affect the motor with soo much overlap? If you had measurements on the port it would be nice to know. Thanks for your input.

z8cw

I am not worried about the overlap in a turbo engine. You will move your max tq up and accomplish more hp at higher rpms with loss of hp at lower rpms. The problem with taking the sleeves out is your port towards the exhaust is getting even larger. It won't match up even with a large port job. For my taste it is to large in the stock version with the sleeve. I am currently building an engine where I will fill in the ports with aluminum and then grind away so the port will maintain a similar diameter form inside to outside. Don't ask me about the aluminum filling. My alu fab guy will hopefully do a good job. The port then will be coated.



Not sure what your time frame is but if you are patient you can learn from my experience in the spring. I think Rice Racing is running a large port with no sleeve and loves it.



CW

fdracer

no it's fine w/o the sleeve, normally part of the housing is exposed before the sleeve anyway and it holds up fine. sorry no measurements, but once the sleeve is out you just open up the port to the size of hole that you're left with. obviously such a huge exhaust port has it's drawbacks including excessive overlap and a shorter power stroke. however, if you want to spool a huge turbo this is the way to go. the ability to run a much bigger turbo, especially a larger turbine side, will more than make up for the power lost from the lower efficiency.