Chris Ng

Well, took the car to the dyno for the first time since the new turbo setup..
Afrs were around 10.8 - 11:1 @ 15.5psi boost on pump gas..
The motor is an S4 13bt with 3mm seals.. this was never the strongest motor, showing aprox 72-73 psi on both rotors.. Compression numbers have been the same since I purchased the car..
The turbo is a TD07-25G .. Tial 40mm wastegate with a .6bar spring

While the peak HP and Torque numbers were actually better than I wasa expecting, concidering the compression numbers of the motor, I was curious about the lack of low and midrange power/torque.. any suggestions or comments on how I could perhaps improve the bottom end a bit? or do the curves on the graph look correct for this setup? I'm using an old style HKS FMIC with 2.5" cold side IC pipes.. the hot side pipe is only 2.25".. whats the possiblility that i may improve thigns by changeing the hotside to 2.5" pipes as well?

Anyways, any comments are always welcome..

Infini IV

What's your timing like in those regions? Although I've never dyno'd my car, I felt a considerable improvement messing with timing in the low rev, lower boost areas.

Wargasm

What is the exhaust A/R?

Maxthe7man

Chris, look at my first dyno compared to yours, its almost identical, even though different turbo, and lower boost... I think its called sick motor syndrome, the 2 motors are almost identical in their curves, and gain, just about like its the same car...go figure...max

IAN

iTrader: (3)

I have identical results as you. This is with my T04B.

I had bad boost response so no boost until 5k. Car did pull 408.8 though.

I wonder if my motor is going south. Hope not. Its brand new.

Carl Byck

All your numbers look O'k to me...The smallish pipes(my old IC in Chris' car) never seemed to hurt my spool, or power, so take a look at the dyno comparo charts( I forget the site), but I think that your results are typical. how much advance are you running? what split? Carl

Chris Ng

Rather than a "sick" motor that is on it's way out, I would rather call it a poorly rebuilt motor that never had good compression numbers to start with.. the motor has about 40k miles on it since it was rebuilt and the compression numbers haven't changed.. even after all the diffrent setup changes , dyno runs, drag strip runs .. it's been run hard (but always looked after).. But never the less, be it a bad rebuild, or a "sick" motor, the low compression probably has alot to do with the overall lack of low end power the motor is producing...I am hopeful however that I can still tweak a few things in order to get some better low end numbers out of it.. not quite too worried about what my peak power output would end up being...

As for my timing maps.. I'm running a wolf 3d ecu, I unfortunately do not have much control over my split timing, so I have it set to 15degree split through the whole map..
timing was pretty conservative, running between 35-20 degrees under vacume.. 17 degrees at 5 psi, 16 by 10psi and 14 by 15psi..

As for boost response, I see boost start to build in 4th gear by 2800rpm, 5psi @ 3500rpm, 10psi @ 4000rpm, 13psi @ 5000rpm, 15.5-16psi @6000rpm ... I have a feeling perhaps that part of the bosot response problem I'm having is due to my wastegate and creep.. I originally had my 40mm wastegate open vented to athmosphere.. with the .6 bar spring (aprox 9psi), and my boost controller turned off, I would see a 10 psi max boost ... however the open vented wastegate was a little too loud for my (and anyone near me) ears.. so I had it plumbed back into the exhaust... since doing that, I now see about 12 psi with the boost controller turned off... with the boost controller turned on, It will hold 13psi until right until about 6000 rpm, when boost will suddenly move to 15-16 psi and hold...

Now, since the profec B I'm using as a boost controller has no readout as to the boost setting you want to have set, perhaps I actually have the boost controller set to 13psi, but boost creep sees me hitting 15-16 psi.. because of this, the bosot controller is opening the wastegate earlier, to accomodate for the 13psi setting, and therefore giving me slower spool than I should be getting.. Does this make any sense? So perhaps if I can somehow confirm that the 15 psi I am seeing is a result of boost creep rather than boost controller settings, I can then look into trying to eliminate the boost creep (The dump tube has a rather tight 90 degree bend to get it to mate up with the downpipe)and then set the boost controller up for a true 15psi, and perhaps decrease my spool times...

any comments on this? does this seem like a possible cause for the lack of low end?

Maxthe7man

I don't think the boost controller will think that far ahead of itself, not the profec b anyway, the A might but the B I would hope not..
The under the setpoint boost curve will be dependent on your ability to spool the turbo, by the sounds of it, it builds boost alot like my car use to, hit the gas, nothing nothing nothing, then the power came on, at 2800 rpm in 4th gear with the SP s5 engine, my car would have full boost, I think I had 10psi of boost anywhere over 2000 rpm in 4th gear.. And only 10 psi at 4000 rpm? thats really slow for 4 th gear...time to port...
Yeah thats true about the motor, I think when the sealing is that bad on them, no matter how much good quality cool boosted air you through at them, they will only make so much power, its interesting your curves are the same as mine, and the numbers are similar, even though the td07 is bigger than the t04e and you ran more boost, it shows they will only hold so much combustion pressure regardless of what you throw at it.. to much combustion leaking out of the firing rotor face into the others and past the side seals.. But remember, compression tests mean nothing... ...... .....

https://www.rx7club.com/forum/showthread.php?t=328103

Max

eViLRotor

iTrader: (2)

If I start in 4th gear, 2500 rpm, i get instant positive pressure, 10 psi @ 3600 rpm and 17 psi @ 4400 rpm.

Chris Ng

I was out on the highway today and tried the same 4th gear test you just outlined.. starting at aprox 2500rpm, positive pressure by 2700rpm, 10psi by 3800rpm, and 15.6 psi by 4600rpm .. so I don't think I'm too far off you for spool .. however, I did not find that I really felt the car start to pull hard until 12 psi.. anything below 12 psi and the car accelerates fine, however doesn't have that "throw you back in the seat" type rush.. as soon as it goes beyond 12 psi, then the car definitly felt strong...

However, while on the highway, I did manage to do quite a bit of tuning with my fuel setup.. and as far as I can tell, it has made a big diffrence with my midrange power (3500-5000 rpm).. it pulls quite a bit stronger .. my low range, (2000-3500rpm) is still quite anemic though... not that I'm going to be doing any racing from starting at 2500rpm in 4th gear.. but it definitly does take it's time before reaching 4000rpm, when things start to move as they should...

the dyno should tel lthe story when I get back on, if my tuning has made any diffrence or not.. I'm keeping my fingers crossed...

eViLRotor

iTrader: (2)

Chris, here is a breakdown of my 91 octane ignition map, its a little bit more aggressive than yours, but I have the S5 engine, and its still safe. I'm betting you could get a little bit more aggressive too.

12%: 35.9
25%: 34.1
37%: 27.1
50%: 23.2
62%: 18.3
75%: 14.1 --> 13 @ peak torque --> 15.1 @ 6500
87%: 12.0 --> 10.9 --> 13.0
100% 9.1 --> 7.1 --> 9.1

I can send you the map if you want...