Ultimate 930 Dyno Thread!

[tj930]

Woah! Woah! Guys!... I have a certain amount of agreement with both of what you guys say.

For starters, I've taken my car to x3 different 'rolling roads' in my time and seen x3 very different sets of data. Now the runs weren't done with the car in exactly the same condition and on the same day - but the old 'seat of the pants' Dyno is fairly accurate at telling whether the car is running well or the car feels sick.

i) kkk-3LDZ, SC Cams but cracked exhaust header - 220RWHP (Lambs Garage, Chesterfield)
ii) kkk-K27-7200-S, SC Cams, engine rebuild, new exhaust - 276RWHP and 293RWTQ (AET Turbos, Sheffield)
and
iii) Same spec as ii and taken 1 week afterwards - 316RWHP - est. 376FWHP and 404FTLbs (DSA, Oxfordshire)

Since (i) couldn't log AFR readings if they went below 10.5 (it just flat-lined at 20.0 after that point) ; on Dyno (iii) I saw a stock, 7-year-old 996tt register 433FWHP the next run after me; and (ii) doesn't employ a roller but bolts directly to the rear wheels - I'm inclined to think that the guys in Yorkshire have the most accurate Dynomometer.

But let's be realistic here guys - we might as well be talking about 'speak your weight machines'

When you're talking about big numbers, a 1% difference is itself a big number! Tuning on the Dyno is a great idea for getting a base map sorted out, but what REALLY matters is the tuning on the road because that's where the car spends its life. (It's just too easy for Dynos pulls not to be conducted in repeatable, Scientific, controlled conditions.)

And, Brian, early in the thread you made a fair point about air intake temperature into the turbocharger... Well I've got a graph (which I'll post up as soon as my FlickR account reactivates itself) taken on the 2nd Dyno, which shows the repeatable results of adding a blue 'air scoop' to pull colder air from rear wing instead of from above the warm engine. (My car has had the broken air conditioning unit removed, so there is an open hole to the outside world.)

The graph shows a difference of 19.2 RWTQ and 14.4 RWHP. But do I feel any difference when driving the car (with an additional 17FWHP)? Not a jot of it - I want to do 2 controlled 60-130 runs (with and without) and see if there is any positive effect.. I'm doubtful - I reckon the scoop's extra few grams of weight may actually slow the car

[drmatera]

why not do a one gear pull ( say 3rd in a 4 sp car and 4th in a 5sp car) from 2000rpm to 6000rpm. That negates any shifting errors and tire spin. Datalog the rpm vs. boost and the time it takes. My megasquirt can do just that. When i find the time this weekend i'll see what happens.

[RarlyL8]

"We have seen 1.0bar at 2600rpm on a 400WHP CIS 930 which produces more than 180WHP @ 3000rpm... "

This statement is total bollocks

So I can assume that any dyno graph that I produce to the contrary will be equally unbelievable.

FWIIW, my professional background is in Quality Control. I have developed quality management systems for instrumental methods of analysis and know a thing or two about reproduceability and metrics. I use the same dyno shop for all my testing and the same parameters with standardized correction factors. I have run my car's baseline many times under varying conditions and it is with +/- 3HP which is 2% total variance.

Would not a better, and more polite, response be "how did you do that"?
Closed mind attitudes make posting anything a waste of my time and drives home the point of why many experts will never post on a forum.

[JBL930]

You can see how long a gear change takes on the graph from the data logger, and starting in 2nd and crawling along at 30-40mph on a nice dry level road you'd be hard pressed to spin the wheels, unless you have monster torque!

I've just done a run, with the new turbos fitted, but not mapped yet so boost is down at 1.0bar. You can see my run isn't smooth so maybe the ECU is pulling timing a bit? I just thought i'd see where it is, 7.34 seconds is certainly in the right direction
I think when i get my RS Tuning map and it's boosting properly, it should be touching 7 seconds. That will be with around 520 flywheel HP, which is around 450 at the wheels?





Back to the 1.0 bar by 2600 rpm on a CIS car with 400HP at the wheels.......
This is a graph with my 930 when it was running a small Garret ball-bearing turbo, it is showing flywheel HP so maybe 350HP at the wheels. My engine at the time had 964 cams, ported and flowed heads, headers, tapered injector blocks to match the ports blah blah.... I'm not sure what model Garret turbo it was, maybe a GT30r, it spooled REALLY quick.



What turbo are you using to get to 1.0bar that much earlier than this, AND make a HUGE amount more power???? I may be an antagonistic pain in the arse, but I call BS

[911st]

Jacob,

Sounds like a very well thought out build and a very good dyno set up by including both AFR & Boost curves! Lots of good info.


Looks like displacment, compression, cam timing, headers, and twin plugs all targeted to help low end and get it into boost quickly.

All these should add up to a pretty responsive build targeted for low to mid range power.


From the dyno plots shown I think I see the following:

1) You might be approaching the limit on fuel delivery.

2) The turbo is reaching its peak efficency at about 4200rpm / 250whp/300chp.

3) Your turbo might be reaching its gross delivery potental (.7 bar @ peak ; .55 bar at 5500rpm).

4) You are reaching full boost (.7 bar) just before 3500rpm which seems late given your build and turbo choice.

5) The test was stoped before the motor hit its peak HP potental. It has a great flat TQ curve that was still holding even though boost was falling off and the test was stoped early.

6) This motor should have about 450whp potental at 1. bar with the right turbo, fuel delivery, and tuning. [((350/ 1.55) * 2)= 450].

A GT 35 Turbo might be a good fit here. It might better hold boost through the upper rpm and do so in a more efficent way that helps keep the charge cooler.

I could be wrong so all I am saying is just watch your boost curve. If you can not hold boost through 6000rpm it is small and could be overly heating the air.

With its ball bearing construction and more efficent turbine it might even boost sooner and help your low end response.

I am not an expert, I just love this stuff so take this for what it is worth.

Originally Posted by jwasbury

...

[911st]

Originally Posted by JBL930

Back to the 1.0 bar by 2600 rpm on a CIS car with 400HP at the wheels.......
This is a graph with my 930 when it was running a small Garret ball-bearing turbo, it is showing flywheel HP so maybe 350HP at the wheels. My engine at the time had 964 cams, ported and flowed heads, headers, tapered injector blocks to match the ports blah blah.... I'm not sure what model Garret turbo it was, maybe a GT30r, it spooled REALLY quick. ...

Johnathan.

A stock C2 makes .8 bar by 3100rpm with stock exhaust and a K27-7200.

Stock cams are going to help boost response. C2 cams have about 1 point lower effective compression ratio because of there later closing of the intake valve.

Were you running a boost enrichment delay. If so that keeps the control pressure higher longer and slows boost response to.

Then the is what gear the car was started in and how early in the rpm range the test started.

Then there is timing, AFR's and other small things.

Not saying something can or can not be done or is probable or not, but with the right set up it should be possible to hit boost at a very early point. That dose not mean it will carry in the upper range.

I talked to one builder that with a very small hot side on a custom KKK made boost at idle on a C2 turbo with EFI.

The best.

[JBL930]

Originally Posted by 911st

Johnathan.

A stock C2 makes .8 bar by 3100rpm with stock exhaust and a K27-7200.

Stock cams are going to help boost response. C2 cams have about 1 point lower effective compression ratio because of there later closing of the intake valve.

Were you running a boost enrichment delay. If so that keeps the control pressure higher longer and slows boost response to.

Then the is what gear the car was started in and how early in the rpm range the test started.

Then there is timing, AFR's and other small things.

Not saying something can or can not be done or is probable or not, but with the right set up it should be possible to hit boost at a very early point. That dose not mean it will carry in the upper range.

I talked to one builder that with a very small hot side on a custom KKK made boost at idle on a C2 turbo with EFI.

The best.

I don't doubt you could make 1.0bar by 2000rpm even.... But show me a turbo on a CIS car that boosts that early, AND produces 400hp at the wheels, or around 460hp at the flywheel...

[911st]

Jonathan,

Got it. And if it did it would probably have a pretty high header pressure at the expense of heat and unrealized upper end HP.

No one in the vocal set of tuners or fellow 930 owners seems to track pressure differentials. They can offer a lot of clues to where our issues or restrictions might lie.

For example:

What is the residual or exhaust manifold pressure relative to boost?

What is the pressure just after the turbo to determine the muffler's back pressure ?

Same on the cold side:

What is the vac just after the air cleaner to determine its restriction.

What is the differential before and after the metering assembly off idle (lag) and at WOT?

What is the pressure drop between the turbo exit and throttle body (IC and plumbing)?

What is the pressure drop through the throttle body?

All info that should not be that difficult to gather and would hold clues as to where the best opportunities lie.

For example. What if we are seeing 2 psi loss on the suction side of the turbo (air filter and metering) and 2.5 psi between the turbo and intake manifold at 1 bar / 5500rpm (intercooler and plumbing pressure drop). With this we know we need to look at the 2.3 bar part of a compressor map instead of the 2.0 (1 bar) part as to the turbos efficiency if we want to hold 1 bar boost at the intake port. Also that there is opertunity to reduce restriction that would reduce our turbo from haveing to work at the 1.3 bar level for lower intake temps.

In a hurry to sell things or save a buck these basics seem to be disregarded. To bad, a differential pressure gage is not more than about $150. Further, with the current crop of wide band monitors, it would not be tough to add a couple of pressure sensors and log some of the basics.

What if we could find that lowering control pressure with first acceleration reduced intake drag 50% for faster spool. What if the fancy muffler is causing higher than expected back pressure at idle or WOT (my B&B style cost me 10% hp at 350whp). Maybe the throttle body starts adding significant restriction above say somthing like 300whp...

Thus a thought.

[jwasbury]

See my comments

Originally Posted by 911st

Jacob,

Sounds like a very well thought out build and a very good dyno set up by including both AFR & Boost curves! Lots of good info.
Thanks

Looks like displacment, compression, cam timing, headers, and twin plugs all targeted to help low end and get it into boost quickly.
Yes

All these should add up to a pretty responsive build targeted for low to mid range power.
Yes...its a damn fun street car right now.

From the dyno plots shown I think I see the following:

1) You might be approaching the limit on fuel delivery.
yep...thinking of shimming the fuel head to see how that helps
2) The turbo is reaching its peak efficency at about 4200rpm / 250whp/300chp.

3) Your turbo might be reaching its gross delivery potental (.7 bar @ peak ; .55 bar at 5500rpm).
yes, the turbo boost seems to fall off...can't seem to keep up with 3.5 liters and opened up intake ports
4) You are reaching full boost (.7 bar) just before 3500rpm which seems late given your build and turbo choice.
I need to install my manual boost control to see if that helps. on this particular pull, I had adjusted the wur to in an attempt to delay enrichment. I also think that this may be a factor in the increasing AFRs at the higher rpms, since as the boost falls off, perhaps the WUR enrichment is impacted too. On the street I see full boost at or around 3k depending on gear and load conditions

5) The test was stoped before the motor hit its peak HP potental. It has a great flat TQ curve that was still holding even though boost was falling off and the test was stoped early. didn't want to get greedy...I told them to stop at 5500 as my expectation was that the K27-7200 would be running out of puff by then anyway and AFRs were climbing

6) This motor should have about 450whp potental at 1. bar with the right turbo, fuel delivery, and tuning. [((350/ 1.55) * 2)= 450].
I think so too...for the moment I'm happy and will be spending my next dollars on suspension and seating...will go for bigger power later or when the K27 takes a dump on me

A GT 35 Turbo might be a good fit here. It might better hold boost through the upper rpm and do so in a more efficent way that helps keep the charge cooler.
yes...recommended by Chris Carroll. Though, I will admit to having a hard on for pkracer's Comp Turbo CT61?...triple ceramic ball bearing sounds like a freaking lear jet.
I could be wrong so all I am saying is just watch your boost curve. If you can not hold boost through 6000rpm it is small and could be overly heating the air.

With its ball bearing construction and more efficent turbine it might even boost sooner and help your low end response.

I am not an expert, I just love this stuff so take this for what it is worth.

[Shadetree930]

I will admit to having a hard on for pkracer's Comp Turbo CT61?...triple ceramic ball bearing sounds like a freaking lear jet.

I added some color commentary with a clip of pkracer's CT61 ...

[911st]

On my old 91 turbo 360rwhp was about my limit for the turbo and fueling even with an Andial Frequency Valve from there Fueler driven at 90% by my programable controler. I had all the goodies, ports, euro FD, headers, straight exhaust, and my C2 intercooler recored to flow about +200% .

Again, sounds like a great build and you know what is going on. If bumping the FD system pressure dose not do it, a higher spec fuel pump might get you there. It seems at higher rates of fuel delivery the stock pumps might not keep the system presssure in the head to spec. Or contact Larry at CISFlowTech.com about his HF FD. You probably already know this.

The best.

[WinRice]

Originally Posted by JBL930

I don't doubt you could make 1.0bar by 2000rpm even.... But show me a turbo on a CIS car that boosts that early, AND produces 400hp at the wheels, or around 460hp at the flywheel...

We could get close if we could get a good selection of variable-vane twin-scroll aftermarket turbos.

Have you seen the torque curve of a BMW 335i?

[911st]

Jacob,

What is the story on the CT 61 turbo?

I looked it up and it looks like they have a broad selection of turbine wheels and housings which could be an advantage.

Assuming the 61 in CT-61 stands for the compressor inducer size and depending on the hot side choice, it sound almost like a GT 35.

Something else, they are working on a turbo that dose not need an oil supply. Interesting.

[jwasbury]

Pete (pkracer) has one on his '77 and loves it. I don't really have any details other than it sounds ri-god-damned-diculous. Put on some headphones and listen to Shadetree's video. When the time comes to replace the K27, I am tempted to go this way too.

Originally Posted by 911st

Jacob,

What is the story on the CT 61 turbo?

I looked it up and it looks like they have a broad selection of turbine wheels and housings which could be an advantage.

Assuming the 61 in CT-61 stands for the compressor inducer size and depending on the hot side choice, it sound almost like a GT 35.

Something else, they are working on a turbo that dose not need an oil supply. Interesting.

[cal007]

Hello together,

attached you can dee the dyno data of a stock 3.0 l Turbo from 1977.
The only modifications are the unmounting od the thermoreactor (so it comes to the European layout) and a real load of 1 bar (made a control measurement).

Everything else is stock equipment, even the turbo (3LDZ).

Of course the power is rather "calm" in comparison what I have seen in this thread before.
But as this car is in mint condition no further technical changes will be made, to keep it original as much a possible.

Cheers, cal

[911st]

Is this a run up through the gears?

Originally Posted by cal007

If so this shows the opertunity from close ratio gears!

3rd and 4th stay in the 240-300 range.

However, with the shift into 2nd it drops way down into the 150 range.

[cal007]

Hi 911ST,

right this is a run through the gears.
I also see the the drop from 1st to 2nd gear critical.

But there is one critic on the graph. It shows the gear shift rpm at 6050, which is below the max rev of around 7000 rpm. Therefore the drop might become less intensive if reving up to the max.
I let draw another graph showing the max rev. The program only showed the rpm up to 6050 as the torque/ hp graph has been cut at that point (the curves already passed max values...)

Cheers, cal

[cal007]

Hi,
this is the graph for rev up to 6500.

[911st]

This is such a great way to show info on the average Hp per gear!

Increase the average HP per gear and the car gets faster.

Think about it, if with the shift into second at around 80k / 50mph we could come in at 260hp instead of 190HP how much faster the car would feel right where we use it the most.

Thank you!

[dh930turbo]

My Euro 88 930 is stock except for stainless sports exhaust (muffler) and made 318 bhp!
I will post the graph as soon as i can find and scan it.