cembrent

Looks good. Nice job.



Brent

G_RIDE

Ok... I need some input. After looking at every thread from here to Tokyo and my eyeballs are bleeding from looking at the monitor for sooooo long, I still don’t have a good answer on exhaust port timing.



I understand the principles… the taller the port the later it stays open and the more overlap induced. More overlap is not great for the idling aspect, but if all your worried about is WOT then who cares; you can set your idle at 2000RPM and forget about it.



Seems to me that two things would happen when you lower the exhaust port, 1st is you reduce the overlap which helps smooth out the idle. 2nd it spools the turbo sooner which in turn should lower the power band thru the RPM range. Both seem like positives to me for a street driven machine.



Now that said; who has experience with exhaust port timing?



Has anyone used a tall port then rebuilt the same motor using the same size port but lower. How much lower did you go? what happened?



What is considered a “Tall” port… 100mm, 110mm, 115mm???



Feel free to point me in the direction of a thread I may have missed

G_RIDE

a little more work





[attachment=37004:attachment]

l8t apex

Rick Engman turbo port.

l8t apex

mine with initial rough cut.Ito then cleaned and bevelled.

G_RIDE

motor is taking longer then expected but here are some more pics

alaskarotorhead

rotary exhaust port timing is similar to a 2 stroke in some respects.the lower the exhaust port opening the less time the power stroke has to push the rotor due to the earlier opening.at high rpm's exhaust gases are allowed out of the engine sooner this hurts bottom end if port opening is excessive.the closing timing is similar,higher hurts bottom end due to overlap but top end is increased.if your going full bridge like your picks,bottom end was not a huge concern.I have seen jap tuners port up to 112 mm, down to 67mm and out to 12mm on the sides on what they called a stage3,I don't know what intake ports they were using though,but were in the neighborhod of 700 to 800 whp.I can say that the guys I have seen port higher than 105mm do tend to taper the port (narrow) at the top.I pesonally like around 102mm high 72mm down and 13mm sides of course depending on the intake ports and car useage.some builders warn on going to high on ports,so I have been hesitant on going up much more than 105mm.allot of guys only port down and touch up the top than widen,but looking at your intake ports you most likely want more.....you should only roll (bevel) the edges about 2mm like the factory for more seal support,but be sure to keep your corners rounded so your closing edge doesn't slam the seal in the rotor.

search BDC's posts,he has way more experience with bridge port turbo's than I do.hope I helped some





Nick

G_RIDE

Good info Nick, thank you. I am also building a street port



[attachment=37458:attachment][attachment=37459:attachment]

bcrx7

Just remember that this being a turbo, you want to minimize your overlap or u will end up with your turbo spooling itself

Buckyfd3

I'm doing an aggressive street port on mine. Got the inlet templates but no exhaust.



Can someone give me some sizes/diamensions of the exhaust port I should use.



Going for 500rwhp