Russ Murphy

I almost forgot. I had a driver to help me with tuning for the first time this morning. I've raised my rpm fuel values across the board closer to rage's. I must have a little more fuel pressure because there's no way I can run more without having tiny MAP/fuel values at idle and that's no good (the percent jumps between small values is to great, 1 to 2 is a 100% increase, 10 to 11 is a 10% increase, etc.). I was still getting some knocking at 10-11 psi so I resloped the MAP fuel values above 1 psi. We ran again with slightly more boost and no knocking until 13.9 psi and guess why? I looked at the injector duty cycle and it was at 109%! And guess what, it can only flow 100%. So, like rage, I've run out of injector capacity only it's at 12-13 psi instead of 8.5. So my guess is that at 3 bar fuel pressure 100% duty cycle is probably 320 crank hp assuming that fuel isn't streaming out the exhaust and it's not because it actually was starting to run lean.

Standalone kicks #ss!

rage2

Congrats Russ. You're all ready for new injectors and a new turbo now! =)

Rob

Russ,

First off, Nice work and Thanks for all the info!!!

What size turbo are you running? Is it a stock 26/6 or a /8? Have you done anything else to the motor besides the SDS? The reason I'm curious is, if so, I'm surprised you would max out the injectors at only 12-13 psi of boost. I know that with the SDS and a MAP sensor you have eliminated any intake restriction, but I wouldn't have guessed it would provide that much of an air flow difference.

Thanks again, and continue to keep us updated.

Rob

Russ Murphy

Rob,
The motor is completely stock and the turbo is the k26/6. The only engine related upgrades are MSD ignition and 2.5" cat replacement and
a Borla Sportsman racing muffler (with the stock tip welded on ). Yes it seems like a large efficiency gain for just an free-flowing intake, but remember the fact that the turbo is working at a much more favorable compression ratio now ( much lower charge temps). I wish I knew what they were before, but they're pretty low now. I've been to busy looking at other functions to really have a handle on what the charge temps are aat a given boost, but it seems like it's hard to get it up above 90-100 degrees. I'll look more closely today. I'll also do a 60-100mph 4th gear pull to give you guys some substance relating to the performance. When we were tuning the car yesterday it went from 60 to 120 awfully fast and 90 to 120 seemed faster than 60 to 90.

Rob

[quote]Yes it seems like a large efficiency gain for just an free-flowing intake, but remember the fact that the turbo is working at a much more favorable compression ratio now ( much lower charge temps)<hr></blockquote>

I'm sorry, but I don't understand. By a more favorable compresiion ratio do you mean running at 12-13 psi? Running a lower boost will definately lower air temp going into the motor, since compressing air heats it up. I am just really surprised that your maxing out your stock injectors running stock boost levels and a less restrictive intake. There are many who are running larger turbo's and a MAF running 18-20 psi of boost on the stock injectors. I find it hard to believe that the maf are that big of a restriction. With Rage's motor having a larger turbo and an extrude honed intake (also some cylinder porting? IIRC), I understood that he very well could have gotton the additional airflow at a lower boost since pressure comes from restriction to the airflow. But I just don't get it in your case and am wondering what is going on here. Maybe I'm just lost or missing something.

Rob

Luke

[Russ,

the MBC in the cig lighter is brilliant!!! <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

michael2e

Russ, if you should happen to find a bit of time, now that you have several of us hanging on your every word would you mind expounding upon those aspects of the install that you found the most challenging while it is all still fresh in your mind. I for one am very grateful for your insights - especially having done most of the work yourself. Thanks

mike

Danno

"I'm sorry, but I don't understand. By a more favorable compresiion ratio do you mean running at 12-13 psi? Running a lower boost will definately lower air temp going into the motor, since compressing air heats it up."

Remember that boost-pressure and flow-rate are not the same thing; you might be getting them mixed up or combined. Take two identical turbos and have them power two different engines, and you'll get different boost levels. Boost-pressure is determined by the restrictions in the engine as air flows through it. This includes the intake, heads & valves as well as the turbo and exhaust.

Let's say you bench-test two turbos outside of the car. Say... two K26/X type of turbos and at 110,000rpm, they churns out 300CFM of air.

Then let's say we put these two turbos onto two different engines; one stock and one modified for free-flow. These two identical turbos would then yield 18psi on the stock engine, and 12psi on the modified one, for the exact same 300CFM air-flow rate from the turbo. Both of these engines would then produce close to the exact same power output. Except for the higher-temperatures of the intake air in the 18psi stock engine. You'll have to find the intake-air temperature differences from PV=nRT and the efficiencies of these two identical turbos at different pressure-ratios to figure out exactly what the power difference would be.

From empirical data, we've seen that most of the time, in most of these cars, 280-300rwhp is where the stock fuel-injectors gets maxxed out. So in Russ's case, he's probably getting around 280-300rwhp, or about 100hp more than stock at the same boost level. Time for bigger injectors...

aka 951

With a map sensor, the turbo intakes air directly from the air filter without any type of air metering device.

Less of a pressure drop between the air filter and the turbo enables the turbo to run more efficiently.

Russ Murphy

Michael,
Removing the speed and reference sensors was a hassle, but I didn't need to do that. Running done all the wiring with no electronic experience was time consuming. If I had removed my seats it would have been a lot more pleasant. <img src="graemlins/crying.gif" border="0" alt="[crying]" />
I tryed to pull wires through the harness accordion boot into the firewall without pulling it offf the firewall or cutting the skinny end open and damaged one of the leads and connectors.
I ended up cutting it lengthwise and then zip- tying it afterwards and that made things MUCH easier. Really all th SDS related stuff wasn't too bad. It was all the maintenance related stuff that had me pulling my hair out.

Rob

[quote] Remember that boost-pressure and flow-rate are not the same thing; you might be getting them mixed up or combined. Take two identical turbos and have them power two different engines, and you'll get different boost levels. Boost-pressure is determined by the restrictions in the engine as air flows through it. This includes the intake, heads & valves as well as the turbo and exhaust. <hr></blockquote>

I agree with everything you said, but since Russ is running a stock turbo and everything else is stock from the turbo inlet to the turbo dump pipe. Were does the reduction in restriction come from, that he can provide more airflow at a a lower pressure? I realize that the inlet to the turbo is now less restricted and if I understand correctly should allow the Turbo to spin up higher & quicker. But spinning the turbo up higher would provide more boost with the same restriction after the turbo, correct?

I'm not trying to be difficult, I would just like to understand, since I would love to go stand alone in the future.

Thanks,
Rob

aka 951

Turbo efficiency is a measure of how much air is compressed and how much air is heated.

More efficiency equals more compression and less heating.

Hot air at 15 psi contains less oxygen molecules than cold air at 15 psi.

More oxygen equals more power.

Rob

[quote] Turbo efficiency is a measure of how much air is compressed and how much air is heated.
More efficiency equals more compression and less heating. Hot air at 15 psi contains less oxygen molecules than cold air at 15 psi. More oxygen equals more power. <hr></blockquote>

Completely understood, I just wouldn't have thought having a MAF on the intake side of the turbo would add that much heat to the intake charge.

Rob

aka 951

Either would I. The dyno should tell the story.

Russ Murphy

We had the same discussion about rage's car and maxing-out the stock injectors. His were maxed @ 8.5 psi and a number of folks were disbelieving of the FACT that he was a 100% duty cycle a that low of a boost level. After dynoing (well, sort of, the dyno couldn't provide enough resistance :eek
and on road dynoing the grossly increased efficiency was borne out. 404 ft/lbs I believe was the number. My injectors were operating a 100% approx. 12.5 psi and all of the fuel was combusting for sure since the motor started knocking at 13.9 psi with the injector duty cycle @ 109% with plenty of ign. retard (10 degrees).
If it quits raining I'll do a 60 to 100 4th gear pull. That should help clarify things.