Danno

Yeah Red, but this is a TURBO air-pump. Boost-level and actual air-volume is NOT the same. By increasing the efficiency of the engine through head port&polishings, extrude-hone intakes, cleaner & free-flowing intakes, you can flow MORE air at the same pressure (try blowing through straw vs. garden-hose).

So Rage2's engine at 8.5psi may be flowing twice as much air as the stock engine at the same pressure, thus it really can be maxing out his injectors. The stock injectors are good for about 320-350hp and I don't doubt that Rage2's engine is cranking out about that much.

rage2

Hey Danno,

Like to thank you for the detailed install instructions of the ARM1 where the clock resides. My clock was broken (has been for 10 years!) and the ARM1 sitting there is a perfect replacement!

Danno

Hey, you're welcome, and thank you for the acknowledgement. Do you have any photos of your ARM1 installation? I didn't realize my point&shoot camera had a mininum focusing distance of 1-meter, so a lot of my photos came out fuzzy. I should put a note up on the website asking for photos from the next person who does this installation.

Russ Murphy

The way to BIG hp isn't by way of BIG boost.
High boost is a byproduct of engine volumetric inefficiency. When you have a situation like Rage's where a monster turbo working at an effcient pressure ratio is followed by a motor that can consume almost all the mass that's thrown at it, you're at or on your way to BIG hp. Way to go Rage.

[*]undefined [img]undefined[/img] [*]undefined

rage2

Russ, thanks for the comments!

Danno, will take pictures this week for you.

BTW - my injectors arrived... going to find some time to install/retune the beast. Will update more this weekend on the project.

Hope it doesn't snow, 3rd gear runs are quite scary on winter tires right now when the road is lightly damp =). Might have to do tuning on a dyno instead.

Danno

Well, boost really is related to the total power output. The measurement for efficiency is:

So a 944NA achieves:

A 951/951S is actually less efficient:

Even with a more efficient turbo, the TurboS still can't match the NA's efficiency (partly due to lower compression and higher intake-charge temp.).

Check out my dyno-chart comparisons at 951 RacerX website. One of Scott Gomes's older engines put out 458rwhp at 20psi of boost. That's 539bhp at the crank for an efficiency of:

Cutting back the displacement and boost to stock levels, that engine would still put out:

That's quite a bit more efficient than a TurboS even (over 100hp more at the same boost level).

Some of Scott's latest engines are well over 650bhp, wow...

By comparison, Honda's mid-'80s F1 engine was putting out around 175hp/ltr*bar boost on 102-octane gas... double wow....

Red S2

I would like to here from TurboTim, Garrity, or Jon Milledge on any 8.5 psi boost, 8:1 compression, 2.5L motor that makes equivalent HP as at 14 psi boost. The 944 turbo's are extremely VE efficient and approach 95%. More HP comes from more RPM and maintaining VE at high RPM.

The injector issue makes sense since you are not using a rising rate fuel pressure regulator. I believe the injector monitor. Porsche using the rising rate to help out the duty cycle on smaller injectors.

The K2x family of turbos are about 72% efficient at the 2 bar, 300 HP level. Garrett's are about 74-76% efficient.

I still cannot understand 300 HP with 8.5psi boost at 6000 RPM and an 8:1 compression engine.

aka 951

The reason why the injectors are maxing out is because the SDS uses a different type of fueling strategy than the DME. I believe the SDS does batch fire, similar to the TEC unit. Turbo Tim knows all about this and that is one of the reasons he went to 83lb? injectors on his TEC equiped 2.5L 951. Check out his page for more details. And no, at 8 lbs of boost, the above mentioned 951 is not making 300 horsepower. I'd guess at most 220-240.

rage2

Facts :

- 8psi boost (verified by MAP sensor, Apex-I boost gauge)
- Stock injectors @3bar fuel pressure maxxed (103% duty @ 8psi 6500rpm)
- Car is faster than SLK32 (349hp 3100lb) which runs 13.0s down the 1/4 mile. If it's 240hp, it's a pretty hard working 240hp =)
- 72# injectors going in today or tomorrow, boost will be turned up and car will be dyno'd.

No point in arguing anymore about how much power the car's making, the stock injectors will be gone very soon, and I don't plan on dyno'ing until it's installed. I'm more interested in how much power when the car's complete.

Mike B

Neat Rage....I'm looking forward to your dyno results...

SnpDG

"By comparison, Honda's mid-'80s F1 engine was putting out around 175hp/ltr*bar boost on 102-octane gas... double wow.... "

How about a modern F1 V10!

~800 / (3*1) = 266.67!!!!!!

Time to retrofit some Pneumatic valves to the Ol 951.

On second thought maybe a old 1970 914/6 GT

210 / (2*1) = 105!

Who needs a turbo 2.8 with a measly 80hp/ltr*bar!

Oh and the all might 917/30

1100 / (5.7*2.3)= 83.09 what a POS!

I'd take the 914/6 any day....Yeah right

Power equals work/time

Honda S2000

240 / (2*1) = 120

RPM RPM RPM RPM, with of course VE.

rage2

Hey Mike B.

Since you're in Calgary, if you're interested at taking a peek at my beast, it's going to be at Alpine Autowerks Thursday to Friday. Scheduled will be injector install, tuning with new injectors, and just going over everything to make sure everything is in place. If I can get a blow off valve in time, that'll get installed too.

Danno

One thing you have to distinguish is VOLUME from BOOST. They are NOT equivalent. Boost is almost a measure of the flow "smoothness" of the engine. The more efficient the flow, the smoother the manifolds and ports, the SAME volume can flow through easier and the result is LESS BOOST PRESSURE on the gauge. Or another way to look at it is, that for the SAME boost level as stock, you can flow through MORE air in any given amount of time, thus make more power at the same stock boost level.

Take that SAME engine, and put a 1" restrictor plate in, and all of the sudden, the boost-level will skyrocket, yet at HIGHER BOOST, this engine will make LESS power because you're getting less volume through the engine.

Russ Murphy

Hear! Hear!(Imagine hearty british accent) Well said Danno.The turbo supplies volume, the restriction creates pressure.

Mike B

Great idea...I have to do a little shopping but would love to drop by...That woud give me a great opportunity to talk to Marc as well...