[toyotaspeed90]

I have a friend with an 88 celica all-trac..... (i'm mainly asking mr2 guys because, well, i trust the mr2 guys more than the celica guys)...

that car came with the single entry ct26......

now a lot of guys on the celica boards are praising to use the twin entry ct26.... which on this car requires a new manifold, spacer, electric fan, downpipe.....

a friend of mine was going to put a new turbo on his, not necessarily for performance but because his turbo is dumping oil through a seal in it..... we might rebuild it in the long run but we'll see....

so, he got a ct26 from ebay and it turned out to be a twin entry.... so he got the new manifold and the downpipe..... and low & behold it doesn't fit..... he got angry and doesn't want to spend more money.....

the guys on the celica forums are saying they 'notice a difference' between the 2.....

however, i talked to my friend and we decided just to pull the old exhaust housing off of the single entry and put it on the twin entry (which we did).... the exhaust turbines look to be identical, only the housings were different..... now, obviously if they have the same turbines & sized, then the inside of the exhaust housing around the turbine needs to be the same size..... so the only difference between the two is the 'split port' in the exhaust housing leading to the exhaust turbine (and the wastegate was a little different..... but really only aesthetically)...

so, really my question is..... why do people spend the money when they're really just putting the same turbo on the car....?

 

[JekylandHyde]

Why do people spend more money for the exact same part when it is called "JDM?"

I am skeptical that the average bear would ever notice a difference between the twin entry or not.

 

[toyotaspeed90]

that's what i was figuring..... i was expecting/hoping you would answer.....

 

[tHa kNiGHt FaLL]

i'm sure it has something to do w/ velocity or something calculated thru research and developement...

but wha you loose in velocity you'd make up for in volume and vice versa...

velocity in air flow helps w/ torque or low end... volume w/ higher end hp...

but especially w/ a stock setup i couldn't imagine it making a difference

this is my educated guess... i haven't read anything about the twin entry and its benifits over the standard setup...

 

[JekylandHyde]

The twin entry was designed to seperate exhaust pulse widths in order to keep the spool smooth.

 

[toyotaspeed90]

right, no i understand the idea behind it.......

but much like t-vis..... it seems like it was an attempt to make something that isn't all that efficient a little more efficient.... rather than 'fix' the problem (ie, went with the ct20b)

 

[tHa kNiGHt FaLL]

The twin entry was designed to seperate exhaust pulse widths in order to keep the spool smooth.

that exhaust soundwave bullshit is such an insane level of performance... its ridiculous

 

[toyotaspeed90]

um, not really..... most aftermarket headers take it into account

 

[tHa kNiGHt FaLL]

um, not really..... most aftermarket headers take it into account

but alot of tuners do not...

how a soundwave from an exhaust stroke on say number one cylinder because of an incorrect exhaust length can actually bounce of the collector and go back up the runner and distrupt another cylinder during its intake stroke...

your typical tuners do not take that into account and i know alot of tuners that never heard of exhaust savenging...

sure some good header company do take this into account... i agree

 

[toyotaspeed90]

not just some..... most...... there's a reason that they collect in the numbers that they do...

also... using mufflers closer to the engine & using an H-pipe and having longer pipes afterwards can help add some power due to pulsewidths & evening pressures out.... that's very common on older cars....

 

[tHa kNiGHt FaLL]

not just some..... most...... there's a reason that they collect in the numbers that they do...

also... using mufflers closer to the engine & using an H-pipe and having longer pipes afterwards can help add some power due to pulsewidths & evening pressures out.... that's very common on older cars....

x pipes and h pipes promote savenging...

using the exhaust to suck air into a cylinder during valve overlap

 

[JekylandHyde]

Exhaust pulse waves are NOT sound waves.
The issue being discussed is pulses of air flow, not noise.

This can be really simple guys:
It's not different than trying to watch people merge into traffic when 4 lanes comes down to one. Imagine if you had all 4 lanes just going into one lane ... now compare that to 4 lanes merging down to 2 lanes and then down to one lane.

Which do you think would be more orderly?
Which would "perform" better?

 

[tHa kNiGHt FaLL]

Exhaust pulse waves are NOT sound waves.
The issue being discussed is pulses of air flow, not noise.

This can be really simple guys:
It's not different than trying to watch people merge into traffic when 4 lanes comes down to one. Imagine if you had all 4 lanes just going into one lane ... now compare that to 4 lanes merging down to 2 lanes and then down to one lane.

Which do you think would be more orderly?
Which would "perform" better?

makes sense... but the soundwave issue is very important as well...

4 into 2 means two collectors. so the collectors are smaller... when the soundwave travels thru the exhaust and hits the collector because the collector is larger it forces the soundwave to expand and when it does it pulses and sends a larger wave in both directions.... one back up the exhaust.

4 into 1 has a larger collector are the sound wave will be larger and stronger being able to disrupt more.

4 into 2 is better to reduce this... but you loose ability to proper savenge... thats why alot of v8's use h and x pipes.

savenging is a good way to micro force induct air into the chamber by using the exhaust pulses from another cylinder on its exhaust stroke to pull air thru another cylinder during its intake stroke. during valve overlap.

i dunno why i just typed this out when it really has nothing to w/ the topic of twin entry turbo... but i guess its some good info.