View Full Version : Back from the dyno, mixed emotions
Back from the dyno guys with mixed emotions unfortunately.
The setup:
Rotrex C30/94, restrictor, A2A intercooler, 2,5" piping, 2,5" free flow exhaust, stock internals.
Engine: 1zz
First things first, when I parked the car outside the garage I got lots of complements about the looks, the sexy deep exhaust sound and the intercooler :lol: Everybody was wondering what is hidden under the bonnet, and whether it was a kit or custom work. When I opened the bonnet and I said that's my custom rotrex setup, everybody wet their pants B)
While the car was getting ready for the big moment, they were asking me what are the expectations. I couldnt hide my excitement and I said anything around 220 at the crank would keep me happy.
The car was ready for the dyno.
The first run was not what we expected and decided to repeat it. At the second run we knew that something was wrong. The power curve didn't continue to rise after 5000rpm, and we were questioning what was wrong. We did a general check up, sprayed the intercooler with cold water to bring the temp down, let the car to breath for a moment and did the third and final run.
The results did not change................
Power 177.4 BHP
Torque 240,7 Nm
We believe that the restrictor restricts more than it should and we are thinking to over-bore it for an additional 0,5cm?
The positive side is that the restrictor does work in terms of torque.
Here is the diagram, any thoughts would be appreciated
MAHA Dyno
http://i1204.photobucket.com/albums/bb407/fealloy/P1020762.jpg
Not too long ago I seem to recall you posting that you use a C30-84 Rotrex, but in this post you list a C30-94. Can you clarify?
Also, a bit more information on the specifics of the restrictor you're using: size, placement and configuration.
And what size pulley are you using on the Rotrex, and are you sure there's not some belt slippage.
Not too long ago I seem to recall you posting that you use a C30-84 Rotrex, but in this post you list a C30-94. Can you clarify?
Also, a bit more information on the specifics of the restrictor you're using: size, placement and configuration.
And what size pulley are you using on the Rotrex, and are you sure there's not some belt slippage.
REO is the guy that is using C30-84 :)
I am using C30-94 with 85mm pulley, following your steps. ;)
I got the restrictor from rcntype (spyderchat). I am not sure about its diameter but he got it from WEB3.0 and I believe it is the right one, 42mm. Worst case scenario it is 38mm. I am waiting to send me his dyno to check the similarities between mine and his results.
The restrictor is welded on the 3" intake pipe, immediately in front of the rotrex inlet.
I dont believe there is belt slippage because we worked hard to fit the bracket and align the pulleys the right way. Nevertheless it is a good point to consider and I plan to take it to the mechanic, jack it and have a look.
If you need any more clarification please let me know and I ll do my best to provide the best explanation.
nrgizerbunny
09-14-2011, 11:45 AM
what was your inlet temperature above 5000RPM?
From your dyno sheet it almost looks that you're losing boost starting about 4500 RPM.
what was your inlet temperature above 5000RPM?
No idea :gap: However the air temperature didnt exceed the 45degr. cent. at any time
From your dyno sheet it almost looks that you're losing boost starting about 4500 RPM.
This is not the case though. Boost is keep building till 6800rpm which is the cut off, 13psi. Do you remember the differences if using a 38mm restrictor instead of 42mm?
Do you remember the differences if using a 38mm restrictor instead of 42mm?
I didn't try various sizes of the restrictor, and doubt that the difference between 42mm and 38mm would make that much of a difference in output.
nrgizerbunny
09-16-2011, 02:10 PM
I would try a larger restrictor, if the engine is under distress stop the run
Thank you people for your input.
After reading through some posts at spyderchat, I think it is best to do a compression test first, , check for boost/vac problems (i doubt there are any of these), and ask the tuner to indicate the a/f ratio he used. Then i ll consider to increase the restrictors diameter :shrugs:
I'm pretty confident (from my initial experience with a way-too-small restrictor) that you wouldn't see the power dropping after you reached a certain RPM - it would flatten off but not drop.
Secondly, unless I'm mistaken, I believe that Corky machined that restrictor so as to be placed right in the Rotrex inlet and maintain a smooth airflow such as on this one [http://spyderchat.com/forums/showthread.php?23386-ROTREX-Moving-Ahead&p=364042&viewfull=1#post364042].
The one pictured there was initially about 25mm, and later on opened out to about 42mm. Thinking back to the origins of where you got your restrictor from, I believe that WEB 3.0 initially had one made like this when he built that Rotrex setup, but found that it need to be larger and (as he put it) hogged it out. At the time it didn't sound like a nice, pretty machined approach as the original one was.
When you say power, you mean horse power correct?
What you see dropping is the Torque, while the bhp is more or less flat after ~4600rpm.
You are right that the restrictor should have been placed right in the rotrex inlet, but we didnt feel confident doing it so because a lot of pressure was needed to insert it, and we preferred to weld it on the intake pipe. I dont think it makes that much difference to be honest, as long as it is there it restricts the airflow anyways
......You are right that the restrictor should have been placed right in the rotrex inlet, but we didnt feel confident doing it so because a lot of pressure was needed to insert it, and we preferred to weld it on the intake pipe. I dont think it makes that much difference to be honest, as long as it is there it restricts the airflow anyways
If the restrictor was made (and maybe later modified) as Corky designed it, the intent was to maintain relatively smooth airflow right into the compressor blades and to minimize introducing any turbulence into the airflow.
As far as inserting it into the Rptrex inlet, use a block of wood (to avoid damaging it) and gently tap it into place with a hammer. If/when you want to remove it, just unbolt the compressor housing (as you would if you were going to clock it) and use a block of wood to tap it out from the backside.
You have no idea how scary that sounds to me :D
I came back from the mechanic, everything look perfect and we believe the problem is indeed the restrictor (maybe by inserting it in the charger is the solution, but apparently we dont want to touch the rotrex by any means, so over-boring the restrictor maybe the way to go)
Tomorrow I ll take the car somewhere outside the town and try to get some readings of Air-flow vs RPM and plot a graph. If the problem is the lack of airflow after 4600rpm, this graph should point it out. :shrugs:
if marc says wow, means the graph idea is stupid..?
I didn't see any mention, but what sort of engine management are you using?
I'd risk saying that the answer just might be in the tune. What's the story there?
ditch the supercharger and go with a turbo - that thing is putting out less power than a stock GT-S.
smart_rocket
09-21-2011, 05:07 PM
^ I see 240NM on his graph!? ... I'd say ditch the restrictor... then blow the engine and get a 2zz, lol
^ I see 240NM on his graph!? ... I'd say ditch the restrictor... then blow the engine and get a 2zz, lol
The results did not change................
Power 177.4 BHP
GT-S makes 180 bhp
GSBoek
09-22-2011, 09:17 AM
^ I see 240NM on his graph!? ... I'd say ditch the restrictor... then blow the engine and get a 2zz, lol
Let me put that into perspective for you: 240NM computes to 176 lb-ft of torque. That's low, which is why his hp rating is also low, since hp is calculated from the torque produced. On a 1ZZ if you are expecting to see 220 whp the torque number won't be far away.
Rotrex is the way to go guys and I wont let it go prior trying everything.
As i see the restrictor may not be the best idea afterall. I am planning to ditch it and install a bigger pulley, either 100mm or 105 one. I ll make the final decision after doing some calculations.
Curt, the guy that tuned the car is a very reputable tuner and i dont see how his tune may affect the low power...
Marc, the GTS makes 180 but it is slower even with my current setup ;)
Thank you all for your input, if anyone have some input to offer in this issue, I am open to suggestions
All I can say is that the Rotrex'd 1ZZ I first had in my MR2 Spyder (aka Roadster) made ~220-225 RWHP @ 7000 RPM (I forget the torque figure) on a stock block using an 85mm pulley and 42mm restrictor. But something I just thought of which might be your issue: we were using a Supra TT MAF as the OEM 1ZZ MAF runs out of range when you start pushing the power up. Lots of guys replace it with a Subaru STi MAF to work around that problem. The answer might come by datalogging the MAF voltage vs RPM.
A larger pulley takes you in the wrong direction. And lastly, I would judge a tuner's competence by the results of his work, and if he couldn't get you to where your setup should have been, his diagnostic expertise should have stepped in and pointed you to the problem and solution.
2KGTS
09-23-2011, 05:57 AM
Thoroughly boost leak test it. Don't just think it's not leaking.
Kurai
09-29-2011, 05:35 PM
How much psi or kPa are you pushing...it does seem your numbers should be alot higher on a 1zz at the stock 10:1 compression but I dont know enough about the Rotrex setup to say for sure...
All I can say is that the Rotrex'd 1ZZ I first had in my MR2 Spyder (aka Roadster) made ~220-225 RWHP @ 7000 RPM (I forget the torque figure) on a stock block using an 85mm pulley and 42mm restrictor. But something I just thought of which might be your issue: we were using a Supra TT MAF as the OEM 1ZZ MAF runs out of range when you start pushing the power up. Lots of guys replace it with a Subaru STi MAF to work around that problem. The answer might come by datalogging the MAF voltage vs RPM.
A larger pulley takes you in the wrong direction. And lastly, I would judge a tuner's competence by the results of his work, and if he couldn't get you to where your setup should have been, his diagnostic expertise should have stepped in and pointed you to the problem and solution.
MAF may be an issue, however there was an 1zz celica owner with rotrex and stock maf that ran 230bhp.
When I ll receive the uprated fuel pump I ll go to the tuner to have a look at it.
Below I have my Airflow vs RPM graph:
http://i1204.photobucket.com/albums/bb407/fealloy/Celicachart.png
Thoroughly boost leak test it. Don't just think it's not leaking.
I had the car tested for boost leak, and two weeks later i dynod it. It is very unlikely to have a boost leak, however i ll perform another one now that I am installing my new boost gauge.
How much psi or kPa are you pushing...it does seem your numbers should be alot higher on a 1zz at the stock 10:1 compression but I dont know enough about the Rotrex setup to say for sure...
I am pushing 13 psi at 6800rpm. My numbers are very low considering i have a free flow exhaust as well :marky:
Although I can't say with certainty, that 13 psi boost figure is ballpark for those of us who've Rotrex'd 1ZZ's and 2ZZ's with an air-to-water intercooler system. That's based upon using an appropriate pulley size that would spin the Rotex compressor at its 100,000 max at engine redline.
Kurai
09-30-2011, 05:41 AM
That does seem low for the amount of boost you are running but again im no expert on the rotted...most 1zz boosted celica owners I have met have been low to mid 200s on around 10psi.
During my initial tuning I was around 300 + at 15psi at the beginning of the tuning process...but I have a completely different setup as well.
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