Convert my HP reading

[dfink]

Went to the dyno today and finally got some progress, didn't blow anything up and got the engine tuned pretty well. The peak HP that we were able to achieve was RWHP 243 with 185ft lbs. This was at 7000 RPM. Pulled strong right to 7000 then started to fall off. I have rev limit set at 7200.
Anyhow this was on a Mustang dyno. The torque was amazingly flat.
Specs. 3.2 to 3.4 rebore; DC21 cams, JE 10.5:1 with 46mm PMO ITBs and Electromotive TEC3r, peak advance is 30* backing off to 28* from 5500 to 7000.; 1.75" European Racing headers, Dynomax 2.5" X-flow muffler. The dyno operator estimated 340 crank if compared to a dynojet. Oh yeah the car weighs 2200lbs

[Steve W]

243 rwhp is a very respectable number, but why is the data so noisy? Seems like the dyno has issues.

[mca]

Nice! I read some dyno stuff on the forum and it seems that the Mustangs tend to read low. Maybe you are getting even more than 243hp?

Tell me about the AFRs. 12.49 average is pretty rich isn't it? Even the high of 13.5 is around 3% CO (I think). Did you run richer as a means to safe guard against detonation?

Mine is going on the dyno this coming Saturday. I am excited but also a little anxious - only have 2500 miles on a rebuilt 3.0. Did you feel like the dyno runs put a strain on your engine?

[911st]

Sounds like a nice build.

I wonder about your X-flow muffler. It would seem to me you have exaust gasses running into each other if it is plumbed the way I suspect. That would cost you a lot of unneccessary back pressure.

A better set up is a dual straigt flow through and you plumb one side of the motor to in and out the bottom pipe, and the other in and out the top pipe.

At this point it might just be easyer to cut it out and substitute a Flowmaster.

I could be off base.

[911st]

Here is a link to that muffler: http://www.dynomax.com/products/ultraflox.html

This is the flowmaster cross flow that would slot right in: http://www.flowmastermufflers.com/products/index.php?main_page=product_info&cPath=34_156&products_id=3294&zenid=4ecf44ed82b4723346e42f5a240f373a

[mca]

Another question ... how did you read advance? Does the dyno do it or did you have to do that manually?

[dfink]

Originally Posted by mca

Another question ... how did you read advance? Does the dyno do it or did you have to do that manually?

The electromotive system has complete control over the advance. I have verified that it is what is says it is. The TEC3r also has data logging so I can check the advance against the log during the run.

[dfink]

Originally Posted by 911st

Here is a link to that muffler: http://www.dynomax.com/products/ultraflox.html

This is the flowmaster cross flow that would slot right in: http://www.flowmastermufflers.com/products/index.php?main_page=product_info&cPath=34_156&products_id=3294&zenid=4ecf44ed82b4723346e42f5a240f373a

I will probably stick with the ultra flow. It is plumbed one inlet on each side exiting the opposite side. It says it is good to 500 HP full flow. The X should give the advantages of a cross connect. The inside tubes of the muffler are 3". If anything is restricting the flow it is where I made turns in the exhaust tubing. If no sound restrictions I will probably run straight pipes but for initial setup I wanted to be able to hear any detonation. By the way never did ping even at 32* just didn't have as much power.

[dfink]

Just for fun here is an overlay of my current run which has been filtered so the max shows lower numbers. It is compared to my 3.2 with 964 cams and a 911chips custom burn. Guess which one is lower.
Also I am relying more on the AFM feedback that I am getting with the wide band hooked into the TEC3r. Around 12.5 to 12.8 is where Richard Clewett had me initially set and suggested that I stay at so probably won't see many 13s under full load.

[JP911]

Using a 12-15% driveline loss to calculate crank HP (conventional wisdom on this board) you're engine is putting out between 272-279 HP. I guess that number is more for bench racing/bragging rights, but it's still nice to know. Congrats on the outcome!

[dfink]

Originally Posted by Steve W

243 rwhp is a very respectable number, but why is the data so noisy? Seems like the dyno has issues.

Don't know wondered about that myself. He can filter it out (smooth it) but you lose both the top and the bottom so you don't get the max HP reading. I will have do some searching to see if that pattern is normal for a mustang. As you can see on my second chart has a filter number of 10 and shows only 225 HP but the chart is smoother. It is also strange that it smooths in the middle and is funky on the ends.

[RWebb]

Originally Posted by dfink

The X should give the advantages of a cross connect.

- what are the advantages in a muffler?

[dfink]

Originally Posted by JP911

Using a 12-15% driveline loss to calculate crank HP (conventional wisdom on this board) you're engine is putting out between 272-279 HP. I guess that number is more for bench racing/bragging rights, but it's still nice to know. Congrats on the outcome!

In doing some comparisons between the mustang and the dynojet the dynojet gives higher readings. Also by about 14-15% so to get to a comparison of output to a dyno jet 243 / .86 = 282 dynojet number then 282 / .85 = 331 at the crank. I don't know what factor the dyno operator uses but he put the crank number at 340.
I know my old 3.2 did 203 RWHP on a dyno jet bone stock. After 964 cams and SW chip CAT bypass and sport muffler. the results are shown below at around 180 on the mustang. This I would suspect should have been around 220+ on the dynojet given the mods above the 203 reading. That is nearly a 20% difference for this particular dyno compared to a dynojet. This is why I am asking for opinions of conversion. In anycase the engine pulls pretty good and I am surprised that the cams didn't poop out before 7000. The flat torque line seems kind of strange though.

[dfink]

Originally Posted by RWebb

- what are the advantages in a muffler?

The only advantage to a muffler is you can hear better doing tuning and you stay legal at certain venues. The advantage of a cross connect to low end torque has been debated to great extent. This particular muffler just happens to have a crossover so you get you maybe get something out of it other than sound attenuation. Heres how it should be.

[dfink]

A picture of the exhaust in question....
Forgot the picture. It is a silent stealth exhaust.

[dfink]

Stealth mode off

[911st]

Originally Posted by dfink

I will probably stick with the ultra flow. It is plumbed one inlet on each side exiting the opposite side. It says it is good to 500 HP full flow. The X should give the advantages of a cross connect. The inside tubes of the muffler are 3". If anything is restricting the flow it is where I made turns in the exhaust tubing. If no sound restrictions I will probably run straight pipes but for initial setup I wanted to be able to hear any detonation. By the way never did ping even at 32* just didn't have as much power.

I was afraid of that.

The exaust gasses are not merging like designed but colliding head on.

On top of that the amount of overlap makes if flow more like one 2.5" single muffler. And that is if hooked up the right way.

I looked at there tec info.

They say your X muffler with 2 x 2.5" pipes can support up to 590hp (flowing in the in the same direction) and one of the single 2.5 inch muffler can support up to 500hp each.

If this info is true a good muffler with 2 x 2.5" tubes should support 1000hp. That looks like a 40% restriction to me. And that is if hooked up as it was designed.

Sorry about making a big deal about this. I trully think that is costing you power.

Dynos differ but 243rwhp is about 285fwhp. I am not an expert but I think some with stock style intakes running the original flaper are makeing the same HP. I would hope with the ITB's you would be making 300-340hp.

Can you do one dyno run without the muffler?

If so, watch the A/F closely and be ready to abort if it goes lean. If it starts to go lean your muffler is costing you.

Good luck!

[911st]

I posted befor your pic.

Did you dyno the straight pipes?

[dfink]

Originally Posted by 911st

I posted befor your pic.

Did you dyno the straight pipes?

Didn't have the opportunity. I have to get another set of stack-breakers to connect the straight pipes.

As per HP keep in mind this is a mustang dyno not dyno jet. On a dynojet I would expect the numbers to be in the 320 to 340 range. I understand what you are saying about the exhaust but not sure if it is causing a reduction. Haven't seen too many using stock intakes making the 285 range but will do a search.
Any body else care to comment on the exhaust arrangement and it's effects. Perhaps I should do another thread dedicated to the exhaust so the title doesn't confuse things.

[dfink]

I have submitted the question to dynomax tech support to gain their opinion.