wish I would have seen this thread last week! I'm looking at my Hymee cat back that UPS delivered at 8pm tonight. Might have screwed up getting it . My impression was cat backs didn't offer that much difference in horse power . Live and learn I guess!

I think a lot of us wish we had waited after seeing these results. But they are using a wider diameter pipe right? I think that may have a lot to do with the gains they are seeing, and no one else is able to get.

and they say there isn't much to gain out of a exhaust , measured the Hymee, 2 1/2 pipe. Don't get me wrong , the thing is beautiful , but man, $100 bucks more could have a mid pipe also :( , maybe after I get it installed I won't feel so bad.

bigger isn't always better unless you're going to FI though. Sometimes backpressure is a good thing for a NA rotary that lacks torque. But in this case that argument goes down the drain :dunno:

Can't you return it and take the hit on shipping?

I'm not sure about the VDI zoom44, we've seen lots of guy on the dyno that peek before the redline then drop off. I don't think we coulda hit 190rwhp (best onlyracing beat catback run). If that duct didn't open.
For a VDI diagram look here: http://www.step-hen.com/images/6250.jpg

See my attachments below, first is a dyno from May when we were doing the REVI+more testing on my, the second phildox's greddy turbo 8, both show that lack off pulling past the redline. With just the RB catback it would drop off more harshly it wasn't until we put the racepipe on that it started to flatten the part where it it dipped down a bit.

As for the turbo-xs stuff real nice quality, true 3" all the way though breaths real nice the best run of just RB-catback vs. just XS-catback I believe the largest difference was 3.5-4hp near redline. Sound is much louder, deeper and more poppy, but not as annoying as others along those same lines. (uploading clips to my server now 50mb each no way to re-encode on this laptop)

1st clip RB catback
2nd clip XS catback
3rd clip XS catback + racepipe.

With the race pipe and XS catback the CAR is LOUD! just see soundclips, it sounds beastly, think drag race day and the PR rotaries are in town.

I believe the highest racing beat vs the highest XS+race pipe resulted in a 10rwhp gain up top, and around 5rwhp though the midrange. (nathan confirm)?

At the current the racepipe will not meet up with the racing beat exhaust, there is an issue because the RB exhaust tapers down to stock size where it meets up with the CAT pipe while the XS system is 3 inch all the way thought, the donut gaskets won't work.

Note* silencers were removed from the XS catback, mainly b/c they don't look good in there :nono:

everyone enjoy. On the plus side this is by far the best the car has felt after getting it off a dyno, great throttle response everything feels more responsive we think the ECU has up'd the advance a little bit.

polak are you in d.c this weekend? I have finals till friday but then i'm done. I havent had a chance to take a ride in a turbo'd 8. your car is turbo'd right cause i thought i saw about 240whp? Anyway you can check out my full exhaust system and i can see your turbo car if your around. let me know.

Read my post again its a dyno from phildox's car form the i think... Feb. issue of Rxtuner.

^sry i had missed that part...after going in nathans lotus and wrx i would just like to see how the 8 feels with a turbo

take the 172 rb run with a grain of salt is was the first run of the day after that one I think the ecu switched its thinking and started to advance timing.

The first sets of RB exhausts when something like 172, 185,186,187,188,190 so after that first run we were fairly consistant.

The Turbo XS just catback stuff was consitant as well something like 190,191,192,193,194

The XS catback with race pipe was even more so something like 194,193,194,195, etc.

Nathan email me those sceenshots when you get some time tomorrow mark87G@comcast.net

I have to give turboxs some props. Normally companies will dyno once, give you some results, and then thats it. I've never quite seen a company this involved with trying to get consistent repeatable results across multiple cars.

Dyno proven has a completely different meaning with these guys!

Has anyone experimented with richening the 8's fuel mixture prior to 5500 rpm? It stays in the 14's for quite some time before it dips down. I know this doesn't directly apply, but we richened the 6's A/F ratio about 1,000 rpm's earlier then stock, and picked up a heapload of low end grunt. Guess I should probably just read a few thousand old threads and shutup.

I thought about VDI some more and attaching a turbo 8's dyno isn't the best idea for comparison since phildox doesn't hold 8psi all the way to redline so its natural that the power will plateau.

Here is several NA dyno's all showing the same power curve I got at XS, pulling to about 7500 and then a gradual let down.
https://www.rx8club.com/series-i-tech-garage-22/dyno-results-compilation-77031/

fully operational and running correctly(no timing pull from over temp etc) the hp curve should look like this plot from a mustang dyno

https://www.rx8club.com/attachment.p...chmentid=57619

if after 7ish k it doesnt continue upward like that then something is causing a loss of power.

btw 188 on a mustang dyno? thats really impressive

The shape of the above curve is similar to what we observed with Armaant's car. Polak's was almost dead flat from like 7000 to redline.

-Nathan

These are similar to what I got, honestly I just think the ECU is pushing alot of advance up to 7500 and then backing off but I could be wrong is that valve vaccume or electric charlie? Is there any quick fixes?

http://www.deanq.com/stuff/xyntax_dyno1.jpg
http://www.d-mphotos.com/images/rx8/...rinrx8dyno.jpg

see that last one Mark- that's dmp's run yes? i would say that run has a problem. the power SHOULD continue upward from that 7250 point but does not. it stays flat. thats either timing being pulled because of overtemp or a VDI not opening. i would think timing on this graph as you can see the dip when the VDI opens it just doesnt ever recover poperly.

actually one other thing i think it could be is what nathan and i were discussing- loss of the rpm pickup resoulution causing incorrect readings. if the dynojet - which dmp's run was - looses that signal it does not give correct correct results

repost. sorry

This is my dyno w cz on dynojet before the recall flashed

https://www.rx8club.com/attachment.p...chmentid=51204

dang 195 with just a canzoomer? nice :)

see those are good clean runs. hp rampsright up to 8500 like its supopsed to. before and after the cz

Four attachments here
1. Armaant's car: notice the 2 dips in the torque curve and then the rise to redline
2. Polak's car: notice the single dip in the torque curve and the fall off of power
3. A comparison between the two cars. Note the 25hp difference at redline
4. Polak's car with the RB system vs. the full TurboXS exhaust system.

see THAT looks like a stuck VDI to me.

nathan does it look to you like polaks car losses some T and HP below 4500rpm with your system?

I have several plots from his car. It was all over the place below 4500 on his car. I've got a few that look like it gained quite a bit down there as well, but the plots that I picked were meant to show the VDI problem the best.

-Nathan

thanks nathan

Here is a plot showing all 6 runs with the full TurboXS system on Polak's car. Notice the wide variation on the low end.

-Nathan

Charlie this is a vaccume activated valve right....is it possible that it just not opening at 7250 because there isn't as much air moving through the throttle body as if I were truly going 150mph?

Re-evaluating my previous dynograph of the RB parts it does appear that it did open at 7250 not that it made much power by doing it.....

Nathan could we get torque and HP on one larger higher resoultion graph to see if there is indeed a dip at 7250 or at least a zoom in on that area?

no its got a solenoid that opens first then the vacuum operates the vdi

VARIABLE DYNAMIC EFFECT INTAKE-AIR (VDI) SOLENOID VALVE INSPECTION

1. Disconnect the negative battery cable.

2. Remove the VDI solenoid valve. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)

3. Inspect for airflow with the steps in the table below.

*

If it is normal, inspect related wiring harnesses.
*

If there is any malfunction, replace the VDI solenoid valve. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)

Circuit Open/Short Inspection

1. Disconnect the PCM connector. (See PCM REMOVAL/INSTALLATION.)

2. Inspect the following wiring harness for open or short (continuity check).

Open circuit

*

If there is no continuity, the circuit is open. Repair or replace the harness.

o

VDI solenoid valve terminal B (harness-side) and PCM terminal 1W

o

VDI solenoid valve terminal A (harness-side) and main relay terminal C (harness-side)

Short circuit

*

If there is continuity, the circuit is shorted. Repair or replace the harness.

o

VDI solenoid valve terminal B (harness-side) and body GND

o

VDI solenoid valve terminal A (harness-side) and power supply

sorry there are pics but i cant post them at the moment

vacuum side -

VARIABLE DYNAMIC EFFECT INTAKE-AIR (VDI) ACTUATOR INSPECTION

1. Disconnect the VDI actuator vacuum hose.

2. Install the vacuum pump to the VDI actuator.

3. Verify that the rod moves as indicated in the table below when gradually applying a vacuum to the VDI actuator.

*

If it fails, replace the VDI actuator. (See INTAKE MANIFOLD REMOVAL/INSTALLATION.)

Rod movement

Vacuum

(kPa {mmHg, inHg})


Rod movement

–3.6 {–27.0, –1.1} or more


Starts to move

–27.9 {–209.2, –8.2} or less


Fully pulled

1.2 {9.0, 0.4} or more


Fully returned

is this a common problem?

I agree, you should be able to see a slight drop and then ramp up at every intake path change, that's why it's configured that way. Great graph for that purpose :)

It's strange that the RX-8 shows such dips. On the 6 port 2nd generation RX-7's, you didn't see these dips when the VDI or aux ports opened. At the very least it wasn't nearly as pronounced. For the most part it was quite smooth. I do know that if you bring online another set of injectors at the exact same point as a set of runners is opening that you will get a dip but if you stagger these points by 400-500 rpm, the dip can be smoothened out. This info comes from standalone ecu tuning on an RX-7 but I thought it may be relevant. Obviously it doesn't explain everything on the RX-8 though.

It's my first time on this thread, and since I've seen two charts of my dyno up here and Polak has been asking a fix to this VDI issue, here's my 2 cents:

https://www.rx8club.com/series-i-tech-garage-22/experiment-changing-intake-port-settings-76447/
https://www.rx8club.com/series-i-tech-garage-22/above-3750-rpms-doesnt-open-secondary-ports-light-load-76505/

Read those threads. I'll post a pic of my experiment's setup, so you can get the idea on how to disable VDI. It's just a plug behind the engine that belongs to what I call the "solenoid plug trio". I have skinny long arms than enabled me to reach in touch the top plug, count two plugs down and disconnect.

When you see a dip like that, it doesn't mean the VDI isn't opening. Figure this out, the VDI is closed all the way to 7K RPM right? After that, it opens up. If the VDI is stuck closed, then the chart lines shouldn't show any changes right? So how come, there's a dip? That's because VDI just turned open and disturbed airflow :D

right the dip shows a functioning VDI like the mustang dyno plot i linked. flat line plateu at 7250 shows a non functioning VDI. polak's flat lines

hm..when racing beat gutted the entire exhaust system, didn't they only gain close to 8whp or something? how is 20whp gain even possible?

RB removed everything(cat and catback), and therefore no back pressure. I think the car needs some back pressure in order to put out max horsepower.

Backpressure does not make power. It never has and it never will at any rpm. You do not need backpressure. I've written in length about this before.

sooooo does the vdi thing break often? and does it show a CEl when it does or no?

Charlie i took the car out for a drive tonight and the duct seems to be working fine, I'm getting a buzz like change rattling behind the dash everytime I hit 7250 which would seem to indicate that its opening up properally. I really think it might have something to with lack of air flowing though the intake on a dyno that we sometimes get this type of thing.

xzantax interesting stuff did you ever do a proper dyno with the VDI open and VDI closed?

^ If it is lack of airflow, then it should show on my graphs. I have made so many logs on the street and on the dyno. The airflow per RPM is rather consistent in its range. The engine will suck in air regardless of a fan blowing or a freeway run, as long as there is an opening for which air can get through.

No, I haven't dynoed my VDI tests. I'm even thinking of recreating a CZ map for a VDI off setup. I always have a hard time leaning out the 7K RPM range so I end up trimming down too much fuel at that range. With good airflow with the VDI off, my maps will be different this time (I hope). Now, if this rain would just go away for an entire week...

yeah, and a lot of people will repeat that backpressure BS despite a cat converter being in the system, like it isn't providing any backpressure

classic book/magazine experts ... :rolleyes:

Its all about exhaust velocity. Backpressure just pops up because people misinterperate the terminology.

Exhaust sizing and design is all about maximizing your exhaust velocity at a certain rpm range.

there is a CEL for it stuck open but not closed

Running no exhaust at all will not make you the most power. If it did, F1/Champcar/Lemans cars would not have exhaust systems as they are not regulated on sound and emissions. Hell, they even use aero dynamic parts to help get the exhaust gases out faster (look at the backs of the cars)

a good free flowing exhaust system (I'm assuming the turboXs qualifies for this) will help in the scavenging process by keeping the velocity high.

Its very possible racing beat, while running the engine on an engine dyno with no exhaust got only 8whp more than with the stock exhaust b/c the stock system with the cat (Racing Beat always takes emissions into account) doesn't flow that well, so removing the whole exhaust system was a semi improvement.

The key is that no exhaust is not the optimal system. (and thank god, this would be loud as all hell)

Thought I'd add to this also as I didn't see it posted before. But Rotary Performance, out of Texas, has claimed for quite some time on their website that with a midpipe and GReddy SP2 they gained 21whp. This seems fairly in line with TurboXS's claims...

http://www.rx7.com/store/rx8/rx8exhaust.html

In your picture below, it has the catless midpipe and the exhaust. Do you have a picture of the rest of the piping that goes with the exhaust? It should be about 4ft in length.

I'm in as soon as I see the gains on a turbo 8.

http://www.turboxs.com/RX8/rx8txscbe.jpg

to me it looks like a cat back with a resonator...

beers

Nope, I'm positive its their midpipe w/ resonator and exhaust.
But the exhaust is missing another 4ft section, not pictured.

I would expect decent gains on a turbo car. I paid them a visit yesterday. Great group of guys and they have a very well run operation going. Nathan is a stand-up guy. He took the time out of his day to talk with me and show me around the shop. He did mention that the exhaust was designed with a turboed car in mind. So I would expect decent results given the results we've seen on the N/A cars thus far. I was really impressed with their knowledge and experience. I think a lot of the problems that WRX owners initially faced with their ECU will translate into good experience for TurboXS when it comes to tuning the 8. Especially since a lot of those same WRX's are running over 400whp! I'm interested in seeing what they will come up with in terms of their Ecutek(sp?) and eventual FI applications. Looks like an exciting development!

You are correct.

:werd: