Originally Posted by Flyweight
Great results! When can we expect to see higher boost pressure results?
Does the 9180 feel GT35rish on the street?
A .83 T3 is absolutely teeny tiny. It is similar to a .64 T4 in terms of flow which is ridiculous for a rotary.
I don't claim to be an expert but I can read charts and graphs and follow the logic of debates.
One thing I noticed (hence the logic thing) is that turbine housings are not viewed as one component, they are viewed along with the system, the system being the size of the turbine wheel that the housing is paired with. We have a large efficient 80MM turbine wheel and we don't need a large A/R housing tied to it. in fact, we can go smaller with turbine A/R as the wheel size gets larger.
Look at the matchbot that BW provides us. It shows on its plot that a 80MM wheel and .83 T3 A/R flows more than a T4 1.45 A/R 74MM wheel. That is a TON of flow.
I then researched about the difference between a divided and undivided manifold in terms of spool. Some people are split on it but most favor divided housings because of quicker spool and response. BW wrote in the EFR technical broschure that divided housings are perferred for spool. that a .91 A/R divided T4 will outspool a single scroll .83 housing but have the same flow up top roughly. remember that a divided housing is divided and the divide takes up room. a single scroll is a large opening.
Then I got to thinking that they are talking about piston engines and with a lot more "pulses" typically 4 separate pules per turbo and piston engines have a lot of "exhaust downtime". A rotary is different, our single scroll is their divided. We have two large ports that produce a lot more heat and exhaust. We also have a continuous stream of exhaust from each rotor going all the time. I am unsure the effect of this when it comes to single scroll vrs. divided. I was wondering if anyone had any experiences.
I recently tuned a single scroll T3 garrett (I think) 60-1 turbo with a .82 turbine housing (journal bearing). It's a 60lbs turbo for air flow and I guess it could have a stage 3 or 5 turbine wheel on it so I am unsure what the turbine wheel size is. When I tuned his car I honestly didn't feel any choke points and the spool up is pretty damn good. I think its better than my .84 A/R P-trim wheel (74MM) ball bearing 62MM compressor wheel T4 divided housing. I think mine makes more top end power but I wouldn't say these two turbo's are worlds apart. I want better spool, IWG and no BOV stupid chirping sounds.
so I then went to comprable sized turbo's with single scroll to divided to see if I can see spool up differences but its tough to compare when everyones set ups are different. so I didn't want to get too involved with the research in this department. What I did see wasn't mind boggling, atleast on a dyno chart. I know dyno's also read differently.
I am trying to figure out what the differences are between a single scroll T3 .83 housing with BB vrs. a larger T4 .91ish divided housing. If the difference is basically moot on a rotary, I might try a T3 single scroll 9180 or 8374 turbo for a wicked low price.