Dyno results - my 930 Sucks!

[rotorhead]

I put my 930 on a dyno today and it confirmed my belief that the car just wasn't making power.



Yes folks thats a Whopping 113kw or 151hp at the wheels.


Peak (If you can call it that) power was produced at 4000RPM
Mixture was set slightly rich at idle
The run was discontinued because the mixture was getting too lean under boost (0.8 bar).
(I believe the run was done in 3rd gear)

Here is the story behind the vehicle....

Fresh top end rebuild (To fix oil leaks)
New K27-7200 turbo
New rear fuel pump
Stock exhaust/Intercooler.

Any ideas would be appreciated

Steve

[Maltese Falcon]

I assume that your tech also checked/ set CIS line and control pressures ? New spark plugs/ gapped right- and what's the age condition of the spark plug wires ? I've seen dyno graphs with jagged spikes like yours and low numbers- when the ignition was taking a dump. My $.02
Marty

[rotorhead]

Thanks Marty,

New Magnecore wires and platinum plugs.

This is the route I am planning on taking...
New Coil
CIS rebuild
Recheck Cam Timing
Add RSR seals to rocker arms (Noticed a slight leak there)

Put it back on the dyno before shelling out for an EFI conversion

[David]

Are you running on all cylinders? This seems to be something pretty drastic, not just a fuel issue.

[slow&rusty]

Something is DRASTICALLY wrong to make 150wheel hp....there is no way especially with a K27-7200!!!!!!

Did you do a compression and leak down?

You are a min. of 100whp short of where you should be.

Jeez....my '85 Turbo Corolla laid 218 at the wheels at 7psi!

Good luck on diagnosing and hope you keep us in the loop as to what you discover.

Yasin

[cgarr]

Welcome to the 912 club!

Craig

[BlkBird]

My suggestions would be:
1) Dump the stock exhaust and header. I like the GHL system.
2) Add a fuel enrichment system so that you can lean out the mixture off boost but not risk melting pistons when on boost.
3) Kokeln intercooler.
4) Finally consider changing the spring. But you want to ensure the intercooler etc have been installed so that your motor's safety is ensured.

My baby is rated at 389 rwHP and 425 ft-lbs torque. And even then I NEED MORE!

[Dantilla]

Originally posted by cgarr
Welcome to the 912 club!

Hey, now! I've got a 912 (Not much longer, probably), and I'd love to have 150 hp at the crank!

[Scott R]

This is going to sound stupid, and I don't know if this appllies to the 930, but I just finished a complete oil re-seal and put my motor back in to fond out I had about 1/2 the power I had before.

I checked everything, and then I noticed that my rottle plate was not opening all of the way. I guess I reversed the two screws that hold cruise control armature to the throttle arm and it was hanging up the throttle arm, as it hit the side of the housing.

DOH! Anway that was stupid on my part, and I doubt it applies here.

[RarlyL8]

That's a normally aspirated power curve. It would appear you are getting no boost.

[DW SD]

I'd suggest starting with the fundamentals. A compression test would be the first thing I would do. No sense adding more parts to an engine, if compression is not good. I know the top end was just done, but what about the bottom end? Compression tests both, as you probably know.

Doug

[hobieboy]

I had similar incident happened before as well, though I did get 200hp at the wheels.

Other than leak down & compression, I would suggest to triple check your cam timing - that was my problem.

Did you check your A/F with a wideband O2 while on dyno? That might also show something.

[rotorhead]

Great advice guys keep it coming...

It may be something simple like the throttle rigging (I had the steering converted from Left Hand Drive to Right Hand drive when I brought the car home from Saudi Arabia).

I will do a compression test and let you know the results

And RarelyL8... I agree that is what it looks like but I had just installed a quality cockpit boost guage thats shows 12psi under boost

[David]

Originally posted by RarlyL8
That's a normally aspirated power curve. It would appear you are getting no boost.

Good call, there should be a big increase around 3500 rpm.

[RarlyL8]

What type of stock exhaust system is on this engine? Thermal reactors? Cat? Possibly plugged up?
Does the engine run hot?
You can't loose 100HP with no symptoms other than lack of power.
Throttle cable issues would manifest as an inability to reach high RPM under load.
Cam timing issues serious enough to loose that kind of power should cause overheating or detonation or both.
Where is the boost gauge getting its signal? Before the throttle, after, or from the brake booster?

[hobieboy]

Originally posted by RarlyL8
Cam timing issues serious enough to loose that kind of power should cause overheating or detonation or both.

When I had cam timing problem, I didn't have an overheating nor detonation issues because the cam was retarding so much that there wasn't enough valve openings to make power.

Having said that, RarlyL8 is right that there should still be a hump however little when the turbo kicks in.

[Mark McClure]

You said you brought it back from Saudi......did it run OK there? What has changed other than the L2R conversion?

If nothing then check the throttle cable! As suggested it is the only thing to have changed.

Cheers

Mark.......

[arrivederci]

At what point in the powerband are you making 12psi of boost? You should be at full boost by 3500 rpm.

[rotorhead]

Lots of great questions.. let me answer them in order

RarlyL8 -
1. the exhaust is a Stock 88 Euro, no Cat
2. I timed the cams at .71 left and .74 right and will recheck shortly
3. The aftermarket boost guage is getting its signal before the throttle body, from the air pump reference line. The stock boost guage is showing 0.6bar under boost.

HobieBoy
1. The engine runs very cool, it gets up to the first white line and stays there. A lot cooler than in Saudi.

Mark McClure
1. Actually now you mention it the vehicle has always seemed low on power, but this is the first time I got it to a dyno.


jpinkert
1. Boost starts coming in at 2400rpm and reads 12psi at 3300rpm.

Slow&rusty
1. The last compression and leak test was done 2 years ago during the PPI and all the vaues were good.

My 2c
Everyone knows it is either fuel, spark, timing or a combination of the thee that is causing the problem. Would you agree that the best course of action would be to pull the engine check the cam timing and inspect the pistons for damage as a first step? This being the most potentially catastrophic of the three.

[Maltese Falcon]

...also a commonly overlooked problem, the intake gaskets on the intake manf injector blocks. These get brittle, however the engine can run- but the leaks occur under load. I'm sure your tech changed these out (?)
marty