Will a Streetport help spool up times?
 

I'm just curious...Will having a large streetport help spool up times on a single turbo application? A somewhat knowledgeable friend said this, and I was just wondering if he is right.

makes sence, porting allows among other things more air in, which is more air out which would spool a turbo quicker

Anyone else??? That's what I figured...More air goes in...More air goes out...Turbos make boost more quickly...Right?

yup(post whore exposed)

Larger exhaust port would decrease the speed of the flow of the exhaust however, not change the volume of the exhaust.

I dunno... :)

I dont' know if this is true for everyone, but when I got my motor ported, I noticed a significant decrease in low end power but a significant increase in high end power

it could be how the engine was ported, if the port diameter was increased upwards that would lower the low end and add highend

yeah, same deal as A/R ratio.

the larger ports reduce the velocity of the gases travelling through it, thereby allowing for higher rates of flow at resonable velocities. these velocities at low flow rates, however, will greatly reduce not only the rate at which your turbine will accelerate (spool up is slower with a larger exhaust port and A/R ratio, but necessary for big power numbers), but in all applications reduces the engine's effectiveness (efficiency) at pumping gas around.

In short the answer is YES, it will spool a turbo quicker. When we as rotary people refer to a street port, most of the time were talking about PORT TIMING. MOST of the time when a rotary has a street ported exhaust, the timing has changed and the actual smallest ports crossection will be were the sleeve and housing meet. Generally the port opening is just blended to match the sleeve. SO...... the choke point of the port doesnt change and neither does the rapid expansion of the steel liner to were it bolts to a manifold, therefor there is no significant change to the exhaust velocity in that respect (the bigger port = slower velocity thing does NOT apply) BUT........ if the port timing is earlier..... your letting the still very hot and expanding gas out...... sinse its still expanding faster due to being let out earlier and hotter, you get more gas flow which inturn means more velocity. So you get more volume, velocity and flow with a properly ported exhaust. Now if you have the port timing close much later, this might have an ill effect on spool (do to exhaust dilution at low rpm, but top end and volumetric effiency goes up), but the loss isnt significant due to the early open helping spool so much. Hope this makes sense to you, and if anyone dissagrees please clarify were I might be wrong.

~Mike..............

I had heard that porting causes a loss in low end power with a gain at the top, but it made sense in theory at least the engine is able to breathe more freely larger ports therefore resulting in a faster spooling turbo.

Has anyone actually had a single turbo, pulled the stock, healthy engine, and streetported and then felt the difference? I guess that would be the best way to really know.

I'll let you know piano as soon as my engine is broken in. :-)