woooowoooooooo!

 

cant wait to see this

 

Come on Howard stop being a tease and tell us what happened yesterday on the dyno??


Brian

 

Makes me want to finish my twin turbo set up faster, time to call my fabricator

 

things went fine sunday but i did not get it tuned out as we do have what is probably a tuning issue...

i did make 364 ft pounds at 16.2 boost on pump/alcohol at 5686. knock was 9 on the Power FC and declined to 1 at 7950. i also lowered my 200 rwhp rpm by 300 to 4350 V my july session.

more details when i figure something out... then back to the Beyond Redline dyno.

hc

 

Dyno Session 2 Aug 19- 07

While we elected to stop a bit short during this session I do have some data which could be of interest and also have a major problem to solve so I thought I would lay it out…

There are two runs of interest. During both runs we did exceed the july runs as to torque peak and earlier spool however what we found was once torque peaked it took a real dive.

So much of a dive (from peak 364 at 5916 to 240 at 7500) that we decided to make one further run, end the session and figure it out.

We leaned the map globally 3% and turned up the gain on the alcohol to see if we could eliminate a couple of very minor knock spikes .

That run moved the 7500 rpm torque from 240 to 283 and the minor knock vanished.

End of session/// time to do some analysis…

My library of 24 relevant dyno runs from others shows that average torque at 7500 is down 11% from the peak number. Further, 7500 torque averages 11% higher at 7500 than 5000.

My last run picked up 7500 rpm torque from being down 34% from peak to down 22%. The average of the 24 other sheets was 11%. So we made progress w some modest tuning but are still not there yet.

Here are some comparatives:


5000 RPM Torque

average of 24 other sheets 304 ft pounds
HC 317 ft pounds

Peak Torque

Average of 24 other sheets 374 ft pounds
HC 363 ft pounds

Peak Torque RPM

Average 24 dyno sheets 6080
HC 5568

This is interesting to me… only 2 other dyno sheets showed peak torque at my rpm or lower and they were 349 and 317. this indicates to me if I can straighten out the problem I will make more torque and probably at a higher rpm.

7500 RPM Torque

average of 24 sheets 333 foot pounds
HC 283 ugly.



There are a number of potential solutions here. Torque is all about (VE) volumetric efficiency. All of a sudden I go from fairly decent to bad. The two areas are flow and tuning. Flow could be the turbos, the manifolding both intake and exhaust or ports.

I digitally log exhaust manifold (back) pressure (EMP) and it is 23 at 15 psi boost. The compressors are working in efficient areas on their map and should be heading for their sweet spots.

I don’t believe the ports are a problem. They are nicely done large-ish streetports.

The more I reflect on the problem the more I think it is tuning, Rotaries are similar to 2 cycle motors, since they are… and, as such, are significantly more sensitive to proper tuning than their 4 cycle counterparts. The fact that we picked up 43 foot pounds of torque going from mid 10s to low 11s makes the point.

I have a feeling that I am nowhere near the proper tuning neighborhood. I will just let my instrumentation guide me from here out…

I am running a somewhat unusual setup w my twin TO4s and alcohol so I am going to refresh my tuning research by re-auditing the TurboBuick’s 200 pages of alcohol tuning threads and will be back on the dyno Sep 9.

I expect that a proper combination of more timing, higher AFRs will finally raise my EGTs to 1550 F preturbo where they belong. At that point I think we will have a lot different torque curve and some good-er overall numbers.

Data from the 2 runs below

Stay tuned…

HC

Log 8-19 11:30

422 hp and 364 torque SAE corr

rpm 5685-------6038-----------6341----------6748---------7195--------7668---------7898

PSI 16.5-------16.43----------15.36---------14.74---------15.6---------16.43------15.36

AFR 10.5---------10.7-----------10.6---------10.2------------10.2--------10.3---------9.8

EGT F 1046------1115---------1108-----------1156----------1178--------1190--------1238

Knock 14----------20-------------9.5--------------8.5-----------10.3---------17-------------27

IGL 14.5---------14------------15--------------16--------------15-----------13----------14.5

IDC 47-------------47----------52--------------58-------------64-----------67------------67

Fuel P 57.6--------55.4----------57.6-----------56.9-----------57.8----------53.4-------57.1

AIR T 24C-------------------------------------------------------------------------------------------

WTR T 82C-------------------------------------------------------------------------------------------

Log 8-19 12:40

(removed 3% fuel global & changed alcohol gain from 4.7 to 6.5)

415 hp and 363 torque...

much improved area under the curve

rpm 5647--------5984-------6441------6793--------7200----------7635-------------7973

PSI 16.91-------16.83-------15.59-----15.23-------15.47-----------15.59---------14.99

AFR 11.5----------11.4---------11.2-------11.1---------11.2------------11-----------11.1

EGT F 1053-------1145--------1181------1214--------1230----------1256----------1293

Knock 9---------11-------------6--------------5------------5---------------5---------------1

IGL 14---------14-------------15-----------15-----------15-------------15------------15.7

IDC 47--------47.7-----------49.9----------55.4--------58.1------------61.1--------62.3

Fuel P 57.8-----60.1-----------58.3-----------56.9-------58.7-------------58----------55.9

AIR T 23C------3---------------24----------------------------------------------------------------

WTR T 80C----80----------------82---------------------------------------------------------------

EGT is preturbo. IGL is lead ignition (advance). split in boost is 11 degrees. Ait Temp pre meth.

the second dyno chart (below) has more area under the curve.

from my two logs here's the rpm, boost and afr at alcohol introduction. obviously i need to lean base fuel at initial alcohol:

11:30 log
rpm-----------AFR---------Boost PSI
4466-------- 12.7------- 7.25
4621-------- 11.2-------- 8.5 alcohol
4783---------- 9.7-------- 10.12
4966--------- 9.1--------- 11.96
5151---------- 9.9--------- 13.55
5353--------- 10.1------- 15.08
5576 -------- 10.8------- 16.24

12:40 log w 3% global fuel reduction and alcohol gain reset from 4.75 to 7

4480--------- 13.4--------- 7.5
4601-------- 11.4--------- 8.5 alcohol
4731-------- 10.5--------- 9.73
4860--------- 10.3--------- 11.09
4996---------- 9.7---------- 12.51
5151........... 9.9........ 13.62
5326----------10.8--------- 14.79
5490--------- 11.3--------- 15.84

 

how's the dyno graph look, any ignition breakup? how's compression?

 

compression and ignition are fine... here are the two runs data flowed thru Dataloglab and scaled to the dyno's torque readings. note the sharp drop in torque after peak in the first run...


the second run... a bit leaner... better torque after peak but still bad..


hc

 

Looks to me like your torque drop off is caused by the boost dropping off after the midrange rpms. 11% drop in boost and 11% drop in torque...

 

yes, boost fall-off is certainly a factor.

due to a bit of initial overshoot and retracement run one drops 10.29% and run 2 9.9% peak to valley. so both runs retrace close to the same % yet there is a 43 pound torque differential.

average boost run 1 is 15.77 and run 2 is 15.80. not too much difference to account for 43 foot pounds or 18%.

part of that could be a better AFR. run 1 average is 10.3, run 2 is 11.2 an 8% improvement.

hc

 

Do you think it has to do with your IGL settings?
You might try to keep fueling the same but revert to the initial ignition settings, to see if that reproduces the steep decrease in power.

At such high RPMs, I would be concerned that the rotor speed might be increasing more quickly than the flame front can keep up.

-s-

 

I dont want to see you fall into the trap of tuning to the n'th degree chassing mystical dyno outputs and tailoring AFR's and timing based on an artificial world on a rolling road dyno !

Your EGT will never equal what you will get on the road under real load, nor will the AFR or the knock in most cases. I never ever tune cars on dyno to make numbers, i do them on road to make the greatest safest power under sustained high speed loads to my numbers that i know work, then we go to dyno comps or race others and what do you know own them on all occasions in the pump fuel world, lots of racers are experiencing this on track at the highest levels as well in pure meth cars or other types of fuel too.

What she makes is what she makes howard, your overall numbers *tuning parameters are fine in my experience* what ever you face in terms of boost control or drop off in tq is a function of your engine/turbo set up at that boost etc... just wind some more into it and do go experimenting with too much more ign or vastly leaner AFR's for it will only yield heart ache for you I will guarantee you that ! f*ck the other forum off completley !!! all your doing is running a blend of fuel bit of meth mostly pump, i know wnough about 100% meth or pump or leaded race fuel to tell you NOT TO **** with it much more (remembering my warning to you about dyno's and chasing a non real world result).

There is no magic to part fuel blends or AI or full race fuel or straight pump, once you start with the upper regions of power generation (and to do it reliably) you need to stay rich and not use much spark lead *simple as that*, have the right heat range plug in it and wind as much boost as you feel capable of doing comfortably or your system can support and if your not happy with the power band or level of power to boost ratio, change to a known turbo/engine combination or modify your existing one

**do not forget to check your tune (AFR, EGT, Knock) after your dyno sessions with real on road/track logging, I cant stress this highly enough, its the prime source of engine failures and unreliable long term set ups**

 

My opinion is you have too high a back pressure in the turbine housing/wheel specification, I'd like to see the figures of EBP tracing the RPM plot and they would be going noticably up after peak tq.

Twins are more inefficient as you have double the turbine clearances, number of bearings and seals etc involved and alot more heat losses so they never will match a single turbo for power per boost, a single to4s on a street port will make peak tq at 6700rpm to 6900rpm and peak power at about 7600 to 7800rpm and your 1000rpm away form all of that and hence your power simply lags away from not having the rpm available..... which the BIGGEST factor is in your turbo specs *failing some type of blockage in your exhaust system being the culprit*

If your willing to put up with the powerband as it stands and restriction on top end revs,tq then simply keep on winding in the boost and the power will go up and up, in some cases it can extend the tq and power a few hundred rpm further along before having such noticable drop offs though the peaks roughly will stay where they are now. its not as if your a gross amount away from where you should be when taking into account variations in testing and other things, whats it feel like to drive on road????

 

as luke and i were in the car looking at the logs after a dyno run he said... "notice the EMP (exhaust manifold pressure---backpressure), you can see where your wastegate is opening..."

after a bit of slicing and dicing which led to the above chart i sure would agree.

my base backpressure is 11 psi. that's at idle up to zero boost... so if we are going to make boost what's it going to cost us is the question.

if you look at the chart at 16 psi boost the additional backpressure is 16-17 psi. notice how it tracks from zero to 16.

THEN... the wastegate opens. the boost controller was set for 15.5 psi and it overshot so it opened up the wastegate. look what that does to EMP. it dives from 16 to 7 while boost drops about 1 psi.

THEN... the controller decides enough and closes to raise boost. just like slamming a door the EMP shoots up to 25 PSI.

an interesting dynamic. one that argues strongly that you want as smooth a boost as possible.

based on this i moved my solenoid tap from the engine side of the UIM to just behind the throttle body. if that doesn't do it i will tap the compressor housing. i may mess with the gain setting of course.

hc

 

No, what you are seeing is the diversion of gass through the WG (if you had a screamer pipe you would hear it Ll the way through the revs).

What is happening is as the gas is diverted through the WG flow is drasticaly reduced through the turbine *but you still need X amount of HP to drive the compressor* so since the flow is reduced so much through the WG opening and bleeding off up to 30% or more then the only way to make up this energy imbalance is to increase pressure hence the EBP goes up AFTER the WG opens

It happens in EVERY turbo system pretty consistently, the more diverted throught he WG the more the EBP goes up another very misunderstood fact of turbocharging and wastegates.

Power required to drive comp = flow rate, pressure, EGT

(drop either the EGT or the flow rate and the pressure will go up to sustain the same boost pressure) simple energy equation.

 

the controller realizes at a certain point that the boost target (15.5) will be overrun.

as boost has been building, the controller has been cycling the wastegate a bit but now it needs to be much more aggressive...

at around 16+ this aggressiveness turns the escalating boost downward. the wastegate is full open bleeding off EMP to reduce the compressor output.

so much so that EMP drops from 17 to 7. the turbos is still making 15.0 boost from momentum and some exhaust flow. as boost drops the controller closes down to raise boost and my manifold pressure retraces mirror image on the upside.

my point is that while a modest boost variation might be considered trivial it isn't as it leads to a leveraged EMP variation whicc is disruptive.

hc

 

no your wrong, the wg is still open just as it is in every other car, the EBP will always go up after this point and up a hell of a lot the more rpm you use after the WG open point..... seen it many times before.

 

You might be able to get rid of the dip, but the trend will be the same in the EBP especialy at higher revs.... no real other solution for that except to run higher EGT or less bleed through WG system.

 

the basic trend is one for one with boost after subtracting base pressure.

until....

16 psi. then something clearly happens. i suggest it is the more aggressive WG. the EBP/EMP plummets and the boost curve flattens and decreases 1.5 psi.

as EMP turns upward so does boost indicating a less aggressive WG.

BTW, i realize that the WG may be open at very small duty cycles everywhere. i am talking relative degree of duty cycle when i say closed or open.

as far as what happens as we move toward 20 or 25 psi... we will see on sep 9. i am not suggesting it will remain 1 for 1. i don't know and that what makes it interesting.

i certainly don't see any immediate backpressue issue from "twins." boost and emp go hand in hand til 16 psi and at 360+ torque. might the issue develop? sure..

sep 9 should provide some answers.

hc

 

Mate as soon as the WG opens its a down hill slide from there with regards to EBP, you will see it soon enough. There is no magic to it.

Most other turbo systems show much less than 1:1 prior to this point then can go to around 2.1bar v's say 1.7bar (ex to int) to pull a number out of my head
It has nothing to do with the WG closing again and the EBP going up, in fact its the exact opposite

Again only things that fix this *besides changing turbo set up
1. less exhaust system back pressure post turbine
2. higher egt
3. less waste gas going out waste gate (but this can only be done by having less turbine speed/less boost)

Let us know how you go and thanks for putting up the info too btw.

 

Howard,
I couldn't find which boost controller you were using. On my system, I would adjust my Profec B Spec II's Set and Gain to minimize the early peak then boost drop.

Is Rice saying that because you have internal wastegates and that since they dump back into your 3” exhaust that the EGP will continue to rise because of the restriction? Would it rise if your wastrgates were dumped overboard, and your two 3” down pipes were instead connected to a 4” collector? (12.98²” decreasing to 6.49²” vs. the 4” pipe’s 11.76 ²”)
Dumping overboard allows the system to grow at a time when it’s most needed.

Your hypothesis that a smooth transition to opening the wastegate might help is probably a good idea because once the wastegate overshoots and adds its share of exhaust gasses to the system it is difficult to respool the compressor with back pressure going up. Did you notice the small second oscillation as the wastegate cycles?

Again Good Luck With Your Research,
Barry

 

Rice is right on the money. a very excellent and immediate pickup on what is going on.

yesterday i laid the boost V backpressure chart and a dyno chart in front of Luke at Beyond Redline and asked the question:

if i could fix the boost so it didn't vary at target would it fix the motor acting as if it is hitting a wall at 6000?

Luke's answer: no, it is a flow problem w the motor/turbos.

i think my motor is fine so i called Kevin Draper, my go-to turbo guy.

here is where instrumentation helps...

Kevin said i should have close to zero backpressure at idle not 11 pounds.

Kevin said Stage 5 turbines.

the turbos are coming off today, will be at Majestic tuesday and will be back on the dyno Sep 16.

it will be interesting to see the trade-off between the heavier larger Stage 5 wheels (read laggy) and the drop in backpressure. i doubt if excess backpressure helps lag.

thanks to all and especially Rice for being on the money.

to be continued.

hc

 

any updates?

 

thanks for the interest.

i did convert to stage 5 hotsides and have zero backpressure at idle. on sep 23 i was back for my third dyno session at Beyond Redline. we found absolutely no decrease in early rpm boost w the significantly larger (10.8 sq inches of wheel V 9.04) hot side. after a few runs to fix this and that we made a 15 psi pull and made the same power (425 and 365 tq) as with the smaller stage 3 wheels.

that tells me that we have a win win as when i raise the boost the stage five wheels should outperform the stage 3.

we then ran into a wierd knock issue. generally i show knock of less than 10 in vacuum, maybe 20-25 mid range and 10 or so at top boost. all of a sudden i am seeing 40-50 in vacuum. we thought maybe an exhaust leak so we spent an hour or two chasing it w no result. i decided to call it a day so as to find out what was going on.

after going thru most everything i conclude i don't know where it is coming from but it is not an issue under boost. under boost the knock tails off to 10 or so.

i chose to wait a month and install the new FJO Auxiliary injection system, boost control and wideband. i should have the systems functioning before the weekend and will be back on the dyno either this weekend or next.

hc

 

sweet thread Howard, your FD looks amazing, and has a very cool turbo setup. I'm driving down through your neck of the woods this coming weekend to look at a new FB. I'm heading south from Houghton, MI through Iron Mountain, Green Bay, and then i'm taking the south-west highway out of GB to Illinois to a little town an hour west of Chicago. If I wasn't on such a tight schedule, i'd ask if I could see your FD. Maybe on another drive down into Wisconsin (Possibly some RA next summer, after I get my FB up and running).