please help..why are my HP numbers so low

[vitoGT]

After I did PI Intake and cams swap I checked my Mustang (98 GT manual) on dyno.My modsI intake & cams,K&N CAI,BBK X pipe, Flowmaster catback,93 Bama Performance Tune
As you can see I have only 216,7 HP (SAE net!) = 187 RWHP and 377 Nm=278 lb.-fr. (this is dyno in Europe)
It's 216,7 at 4562rpm and after that I have lack of power.Without Bama tune its 214 HP(flywheel) I checked obd codes and everything is ok. Maybe I have problem with MAF, fuel pressure or timing?What do you think about this chart?
http://img40.imageshack.us/img40/1586/50579326.jpg
I checked compeession:
4 160 8 170
3 160 7 173
2 160 6 178
1 170 5 175
Is this normal?
I also have 30 PSI fuel pressure at idle. Is this normal when in my tank is about 10 litres of fuel my car won't go over 4000 rpm ?if I have more than 10 liters about 15 liters is everything ok,but I have 34 PSI at full throttle Thanks for any help

 

[Stan Weiss]

On what dyno did you get these numbers?
Are these corrected or uncorrected numbers?
What was your air fuel ratio throughout the test?

 

[trinity_gt]

Hi,My name is Witek and I'm from Poland In Europe.
After I did PI Intake and cams swap I checked my Mustang (98 GT manual) on dyno.My modsI intake & cams,K&N CAI,BBK X pipe, Flowmaster catback,93 Bama Performance Tune
As you can see I have only 216,7 HP (SAE net!) = 187 RWHP and 377 Nm=278 lb.-fr. (this is dyno in Europe)

Just to clarify: The 216.7 figure is the HP at the wheels. This equates to something like 250HP at the crankshaft assuming a 15% loss. I think you're "converting" the wrong way. No chassis dyno credibly measures crankshaft HP and up-converts to what you'd see at the wheels.

Okay, so you're at 250 crank HP. A stock PI GT (99-04) typically dynos somewhere in the 220-230 range so you're not far off that.

Keep in mind that the PI heads -- or more specifically, the exhaust ports of the PI heads -- are awful and that any extra lift offered by "better" cams is offset by a restrictive exhaust port that stalls at just 0.350" valve lift. As well, the PI manifold and NPI head port shapes are different: the NPI port is smaller than the PI port to the in-coming air has a step at the manifold-head interface that will impede flow some.

The PI manifold and cams are light-years better than the NPI parts but you're still stuck with the NPI heads and, as the saying goes, a chain is only as strong as its weakest link.

You mention fuel issues. How are you measuring fuel pressure? If you're using a scan tool, you should see a pretty flat 39psi or so. If you're using a gauge on the fuel rail, it will vary with throttle opening of course. Using this method, you should see an idle fuel pressure of ~34psi and a WOT fuel pressure of ~50psi or perhaps slightly more.

If your fuel pressure is really low, you may be running lean at WOT and losing power. What's the AFR like?

 

[mogs01gt]

Sounds like a timing issue.

 

[vitoGT]

Just to clarify: The 216.7 figure is the HP at the wheels. This equates to something like 250HP at the crankshaft assuming a 15% loss. I think you're "converting" the wrong way. No chassis dyno credibly measures crankshaft HP and up-converts to what you'd see at the wheels.

Okay, so you're at 250 crank HP. A stock PI GT (99-04) typically dynos somewhere in the 220-230 range so you're not far off that.

Keep in mind that the PI heads -- or more specifically, the exhaust ports of the PI heads -- are awful and that any extra lift offered by "better" cams is offset by a restrictive exhaust port that stalls at just 0.350" valve lift. As well, the PI manifold and NPI head port shapes are different: the NPI port is smaller than the PI port to the in-coming air has a step at the manifold-head interface that will impede flow some.

The PI manifold and cams are light-years better than the NPI parts but you're still stuck with the NPI heads and, as the saying goes, a chain is only as strong as its weakest link.

You mention fuel issues. How are you measuring fuel pressure? If you're using a scan tool, you should see a pretty flat 39psi or so. If you're using a gauge on the fuel rail, it will vary with throttle opening of course. Using this method, you should see an idle fuel pressure of ~34psi and a WOT fuel pressure of ~50psi or perhaps slightly more.

If your fuel pressure is really low, you may be running lean at WOT and losing power. What's the AFR like?

Thanks for answers
The 216.7 figure is the HP SAE Net . It is measured at the engine's crankshaft and so does not account for transmission losses. In Poland we have DIN horsepower which is measured at the engine's crankshaft. When my GT was new it should have 225 HP SAE Net which is 228 DIN PS. I have only 216,7 with all my modifications.Its 187 rwhp+15%=216 crank HP.
I use gauge on the fuel rail, at idle is 30 PSI and WOT is 34 PSI for only 0,5 sec and after that is only 30 PSI (still WOT).

 

[trinity_gt]

Thanks for answers
The 216.7 figure is the HP SAE Net . It is measured at the engine's crankshaft and so does not account for transmission losses.

If you did not physically remove the engine from the chassis then it was not measured at the engine's crankshaft. Please clarify: Was the engine, the intake and exhaust systems and accessories removed from the car and the engine bolted to an engine load cell? Or was the car either driven onto a "rolling road" dynamometer where the road-wheels drive the rollers?

You need to clarify what type and model of dyno was used.

In Poland we have DIN horsepower which is measured at the engine's crankshaft. When my GT was new it should have 225 HP SAE Net which is 228 DIN PS.

Some clarification needed:

SAE net is indeed a value measured by the automaker with the engine on an engine dyno. It's differentiated from the SAE "gross" number that was used back in the 1960s. The difference between gross and net is that net configures the engine just as it would be in the vehicle: Everything from the power steering pump and AC compressor to the alternator, intake and exhaust (cats, mufflers, tailpipes, everything) are in place. While "gross" was measured with the engine driving the waterpump (and that's about it), "net" includes real world losses the accessories, intake and exhaust give. Think of it like a business: You have "gross income" and "net income" which is gross minus expenses...

DIN "PS" is just HP expressed in metric terms. While 1HP is 550 ftlb/sec, a "PS" is 75 kgf·m/s. Do the math to convert a ftlb into kgf·m and you'll find it's just a linear translation. There's nothing special about a HP or a PS.

Most dynos have several "corrections" to normalize results to fixed references of temperature, humidity and barometric pressure. Some dyno operators use no correction, SAE correction or STD correction. Often, they'll let you choose the correction you want to use. But note: the SAE correction factor is not the same as "SAE net."

I have only 216,7 with all my modifications.Its 187 rwhp+15%=216 crank HP.

Assuming you measured the power on a rolling-road chassis dyno, are you saying the actual power delivered to the back wheels was 187? That the plot we see is the dyno operator adding in a driveline loss factor of 15% to derive a curve showing 216?

I use gauge on the fuel rail, at idle is 30 PSI and WOT is 34 PSI for only 0,5 sec and after that is only 30 PSI (still WOT).

This sounds low. Given that you also appear to have fuel supply issues ("when in my tank is about 10 litres of fuel my car won't go over 4000 rpm ?if I have more than 10 liters about 15 liters is everything ok") I'd get the fuel pump and filter checked.

 

[Stan Weiss]

377 Nm = 278.06 lb.-ft @ 3516 RPM = 186.15 HP
366.6 Nm = 270.39 lb.-ft @ 3550 RPM = 182 .77
These HP number look like what is on the graph

Again
On what dyno did you get these numbers?
Are these corrected or uncorrected numbers?
What was your air fuel ratio throughout the test?

 

[vitoGT]

Assuming you measured the power on a rolling-road chassis dyno, are you saying the actual power delivered to the back wheels was 187? That the plot we see is the dyno operator adding in a driveline loss factor of 15% to derive a curve showing 216?

Yes it was rolling road chassis dyno, and dyno operator showing HP numbers (red line on chart), if you want he can tell you RWHP numbers (grey), is strange but in Poland or Germany pupular are HP numbers not RWHP.

here is a new link http://stangi.w.interia.pl/gt22.jpg

Again
On what dyno did you get these numbers?
Are these corrected or uncorrected numbers?
What was your air fuel ratio throughout the test?

He didn't check AFR, he said that I have to do another run and he will choose AFR option.The dyno name : dynotech. I think these numbers are corrected, I'll call him and ask.

My friend has stock 2004 Impreza WRX and he also had dyno-run there and his power was over 2 HP over stock (catalog)data from Subaru .

I have new fuel filter, I will check one more time fuel pressure.
Thanks

 

[vitoGT]

Assuming you measured the power on a rolling-road chassis dyno, are you saying the actual power delivered to the back wheels was 187? That the plot we see is the dyno operator adding in a driveline loss factor of 15% to derive a curve showing 216?

Yes this is rolling-road chassis dyno, in Poland,Germany dyno operators gives you HP numbers, its strange but here HP are popular not RWHP. If you want he can tell you RWHP power but chart numbers are HP. You can see better :http://stangi.w.interia.pl/gt22.jpg My RWHP is 187 .

I have new pump filter I will check fuel pressure one more time.


I don't know AFR becasue dyno operator didnt choose AFR option. I have to do another run to check it. Name of dyno:dynotech, I think numbers are corrected.My friend has stock 2004 Impreza WRX,he had run on this dyno and his numbers are a little better than catalog production numbers (Sae net)

 

[mogs01gt]

Rolling Chassis dyno's the output at the rear wheels. Its RWHP numbers. Those number sound right for a chassis dyno. A chassis dyno cannot properly calculate flywheel or engine HP. The only way to accurately read those numbers is to hook up the engine to a engine dyno.

 

[trinity_gt]

Yes it was rolling road chassis dyno, and dyno operator showing HP numbers (red line on chart), if you want he can tell you RWHP numbers (grey), is strange but in Poland or Germany pupular are HP numbers not RWHP.

Thanks for the clarification. So, the dyno measured 187rwHP peak at the wheels and the 216 computed for the engine is ~1.15x that.

 

[V_Eight]

If your car has a lot of miles it's not going to put down the same numbers as when new. That might have a play in it.

 

[bhuff30]

If the car has been maintaned well, high mileage will have no effect. My 97 GT ran 14.2 with only an H pipe and well over 150k miles. It ran 14.6 bone stock (paper filter and all), a crappy driver and more than 100k miles. Of course, that requires regular maintance: good plugs, a clean air filter, clean fluids, ect.

I think it's pretty clear Vito's power problems are fuel related.

If your car has a lot of miles it's not going to put down the same numbers as when new. That might have a play in it.

 

[vitoGT]

Sounds like a timing issue.

I know this post is old but I found what was the problem, my timing was off by one tooth. Thanks guys for help

 

[nyuk98gt]

vitoGT:

Glad to hear you got the problem solved. Do you have new dyno numbers? I bet your engine feels a lot stronger with the cam timing corrected!

Chris