wade

iTrader: (1)

Yes I am damn near certain the flange bolt holes are identical, but I am more concerned with flow/spool times.

I know how a divided manifold is put together and the characteristics of why a 'divided' mani/turbo is better. But for all practical sakes, for a 400-500 whp car ( 03 s2000 ) will I see any BIG disadvantages in spool times? How much faster would say, a divided gt30R spool over a open turbine gt30R on my manifold and car?


Just looking at options considering how much a new divided 30R costs v. using a Borg Warner or comparable turbo.

Thanks!

JdmTypeRdc2

iTrader: (1)

It will still work, however, the manifold will no longer serve its purpose.

wade

iTrader: (1)

I understand. Just curious on how much if any, the spool is altered by comparing it to a similar turbo in its divided state

JdmTypeRdc2

iTrader: (1)

It will be as if you are running an undivided manifold. The full effects of why one would opt for a divided manifold would not be felt.
Given a GT35r:
Undivided turbo + undivided manifold = laggy
Divided turbo + divided manifold = gt3076R spool (give or take)

If you are really set on that idea, then I would suggest putting the divided manifold for sale, and get an un-divided one.

wade

iTrader: (1)

Yeah, this is all just a thought. I got the manifold for damn near the cost of material, so I would like to use it still. I have a source on a nice BW turbo, just not sure how it will do. I didnt know if having it used as its intended will make Night/Day difference on the spool characteristics

JdmTypeRdc2

iTrader: (1)

I just read your initial post...and i just noticed 2 things:

1. Your an S driver!
2. You mentioned a 30R

Ok, so i will answer again.

No need to divide a 30R, since their spool characteristics are amongst the best in the market. It is an incredible turbo.

I would just use what you have or put the divided manifold up for sale.

The only way I would ever go divided is if we were talking GT40R or so. You get the most from the divided manifold when it comes to big turbos. Anything over a 35R would be beneficial.

With the 30R, you are golden.

sanman000719

this is a t4 devided top mount on a pt67 undevided

TheShodan

iTrader: (14)

Well, we all know that a divided housing (This is not synonymous with "twin scroll") uses a divider wall in the turbine volute to keep the exhaust path isolated from the exhaust port to to the tip of the turbine wheel, specifically the inducer portion. The purpose of this is to allow the maximum use of exhaust gas pulse energy. This means that the amount of energy created during each exhaust gas pulse (when stroke of the engine goes through its cycle creating exhaust gas) is greater than the amount of energy between each pulse. For a divided housing, this allows each exhaust pulse to reach the turbine wheel tip and therefore transmits higher energy to the turbine.

In contrast, an open housing has more efficient and less restrictive exhaust energy movement, but doesn't transmit pulse energy well after a certain size. What this means is that a divided turbine housing is best used on low-speed and midrange turbo matches where engine rpm isn't too high, but peak torque is needed like in a diesel application, or the lower rpm band of a higher rpm standard engine. The open housing is used more on high-speed high rpm applications where exhaust energy is more steady streamed. In high rpm engines, divider walls tend to be more restrictive in the upper powerband due to the additional surface area that causes a loss in turbine exhaust energy flow.

This is why I say that the divided housing has, and typically is present in larger turbo applications like the T67 and up, and why people feel as though they "spool" better in the lower rpm band; its because they do "feel" it when the engine is not cycling over 5000-6000rpms (depending upon application). after that point, the restriction of the housing comes into play. In the above shown example, the only reason it made more power in the top end after the initial use of the divider is simply because a larger volute was used than the T3, which is typical in a T4 divided housing anyway. Evolutions don't rev that high in comparison to Hondas, which is why you don't see the biggest benefit with T4 divided setups, even in the lower range.

What does this mean for Wade? simply that for an engine like the S2000, the only benefit he would see really is a bit better initial flow of exhaust energy due to steady stream of exhaust energy. But that benefit dissipates very quickly as he climbs higher in the rpm range. In the end, he's better off with an Open Turbine inlet if he plans to rev the engine rather high like 9000 or more. If staying GT30R or other midframe-sized turbochargers, there's no need to have a divided housing. Though T3 divided housings are made by ATP in a .78A/R, most tests have shown that for something like a GT30R, you had the mediocrity of both somewhat responsiveness but no better topend power than a standard T3 format

JdmTypeRdc2

iTrader: (1)

^^^Ive always loved your explanations....just had to throw that out there

wade

iTrader: (1)

Agreed. So looks like an open T3 on my manifold will be good

LS AzZkIkr

Should be good. I would say if you have the money to do testing for yourself and see what you like, just buy the turbo you want and look for a used turbine housing that is divided and test them both. The divided .78 sounds really interesting! What A/R would you be looking for with an open flange?

TheShodan

iTrader: (14)

This was based on a few applications by way of a boost threshold/RPM extrapolation from the AEM EMS.

Coheed

Rotary guys like the big housing turbos because of the amount of "overlap" the engines have. They use the 1.06 housing with good results, and they only rev to about 9k typically.

At what point do you suppose the housing and overlap work together? A big overlap engine is going to want as close to a 1:1 ratio of boost/backpressure as possible for best results.

What kind of overlap do the typical GSR/TR cams have? Anyone use big overlap cams on a small-ish turbo with disappointing results?

rs250nut

Why would you ever want overlap on a turbo charged motor? So you can see the boost being blown out of the exhaust.

Uncle Dave

The more improvements we have in turbo and manifold design (both intake & exhaust) the more overlap we can run hence we make more power and better boost response.If you look around and power levels these days we make way more power on lower boost pressures.

W!d3b0dYr3X

shodan, would you please care to elaborate more on this? i remember seeing your signature a while back with a statement from someone saying just because it has a divided housing does not make it a twin scroll. im confused on this concept simply because i drive a mitsubishi evolution 8 and it has a twin scroll turbo system from the factory. the manifold along with the housing is both divided and i was under the impression if it has a divided housing and divided manifold it is twin scroll. so how can one have a divided housing, divided manifold, but it not be twin scroll? i also agree with you that twin scroll helps down low and midrange torque. thats the main reason the evolutions are quick off the line, reaching peak torque and max boost pressure at only 3600-3800 rpm, but i do disagree with you on the fact that they dont rev as high as a honda. the factory redline on a evo 8 is at 7606, whereas most hondas are in the 7200-7500. now on aftermarket applications hondas take the cake reving to 11k sometimes yes, but not on stock applications.

Coheed

Boost rarely ever gets blown out the exhaust. This is a noob statement. No offense.

Reason why? Backpressure on a turbo engine exceeds boost pressure. So when both valves are open, you don't see boost going out the tailpipe. Unless, of course, you have a really big turbo.

You can still take advantage of the scavenging provided by the overlap and high duration in cams. This is why GSR cams make more power than B16 cams.

HiProfile

Most Honda setups run much less drive pressure (pressure between head & turbo) than factory turbo cars. This means they can be run more like NA motors vs others. Supercharged Hondas are the engines you don't want much overlap on, boost DOES blow out the exhaust.