Members Dyno Opinions Requested !

[Street Pro]

Please excuse the length of this post, but we are seriously searching for your “informed opinion” on a complex question. This post is NOT an effort to sell you any product! We appreciate and respect the user guidelines of TDR. We intend to become a TRD Sponsor in the very near future (weeks not months) and will reserve our shameless commercial plugs for that time. Now we just want your honest input into a question that has become very confusing for us. We are posting this question on several other diesel forums and, in as much as High Performance Modifications seem to have begun in the community of Dodge diesel owners, we felt like your opinions should be given proper consideration.



Our company name is Street Pro and you may need to look at our web site to understand the product we are talking about. If you don’t need to look at the site, great, if you do, the site is www.streetpro. us Let me say once again “we are not trying to sell you any product through this post”. We just want your honest input to the following questions.



We at Street Pro need some advice on interpreting dyno results. Here is the background that has lead us to this state of confusion.



We started our company almost 2 years ago with the sole mission to make exhaust cutouts for the gas engine guys. We developed what we think is the best looking and performing (not cheapest) cutout on the market. Upon testing several cars and trucks (gas) we saw a consistent 5-6% increase in both torque and hp at the rear wheels regardless of the baseline power, open vs closed. Everybody loved it and away we went. Hundreds are in daily use today. Then a few months back we were told by several shops and people using diesel trucks to pull gas racecars that our real market for this product was in the light duty diesel, which we knew nothing about. Believing that a “less restrictive” exhaust system is a good thing in any turbocharged engine application, we set out to create the big brother diesel exhaust cutout that we now call the 4" Power Master.



Like the gas 3" cutout, we wanted to test the product and see what was really being gained in terms of power. We believed “real world” over the road performance was the true test of the product but we knew that many people like to quote Dyno numbers. We secured a DuraMax that has an Edge Attitude 5 stage chip and stock exhaust (no cat model). The first dyno test was done with the results being inconclusive. The dyno shop said their dyno (an older model) could not test at such low RPM / high torque. So we then went to a very large local Caterpillar shop that has an over the road truck dyno. I must say the test was unlike anything we had ever seen in that the truck was allowed to run at full load for what seemed to be 2 - 3 minutes per pull (glad it wasn’t my truck!). The tests were done with the cutout open vs closed with the chip set at level 3 (90 hp ???). After a lengthy head scratch session, the senior dyno operator reported to us - 257 rwhp closed and 289 rwhp open and an EGT drop of ~ 100 degrees in the open position.



Since that time, a member of another diesel forum (primarily DuraMax) was given a unit to test to help validate the numbers and he got a VERY different result. His truck is equipped with a Banks Six Gun (hp ??) and a Banks Monster Exhaust (with cat). With our part installed after his cat, his test indicated only 4 rwhp improvement.



On another truck tested at Garmons Diesel Performance in McDonough, GA last weekend we saw a 4 rwhp gain on a stock '04 Dodge by using the cutout to bypass the muffler.



The Dyno test on both the Dodge and the DuraMax seemed to allow the engine to run at maximum throttle for 10 to 15 seconds as opposed to the almost brutal 2 to 3 minutes we observed at the Caterpillar dealers facility.



A respected individual in the light duty diesel performance business tells us that the cutout when used to bypass the cat and muffler should yield 10 to 12 rwhp improvement when tested in the “short burst” type of test.



The obvious questions: Why did the DuraMax at the Cat dealer show such a strong gain and the other 2 were so low in comparison ?? What is the “real world” application of this information? Any help would be appreciated so we can properly understand the true benefits offered by our product in the diesel marketplace.



Thanks for you opinions. We’ll see you again soon as a TDR Sponsor!



Street Pro

www.streetpro.us

 

[GWoody]

I can't begin to give an explanation on the different hp readings but I am curious if all of the tests showed a significant decrease in egt. This cutout might be useful when towing heavy in the mountains.

 

[Street Pro]

I can't begin to give an explanation on the different hp readings but I am curious if all of the tests showed a significant decrease in egt. This cutout might be useful when towing heavy in the mountains.

Thanks for the reply --- I was presonally present at the test at the Cat dealership -- that test did show a EGT reduction of approximately 100 degrees --- The Dyno run of the 04 Dodge, which I also saw, lasted only 2 to 3 minutes of total engine running time including the driving up onto the Dyno -- the engine was even shut off while the truck was strapped down on the Dyno -- the "run" was so short in duration that they did not even put a fan in front of the engine like I often see in gas Dyno runs ---- There was no EGT report given that I know of --- We do get reports from users who pull loads (horses, boats, campers) and they say the engines "seem to keep on pulling" under a substained load ---I guess that's what we are having a hard time understanding????? Would a "short burst of power" type dyno run truly take into account EGT issues ???? Please understand that we do not question the "value" of any Dyno testing -- we just want to understand what the data means to the "everyday driver".

 

[JGK]

Street Pro,



Your initial test at the Cat dealer was on a DuraMax with a stock exhaust. Presumably your cutout was place as soon after the turbo as practical.



The second DuraMax test was on one with a monster exhaust with the cutout after the cat.



On the Dodge, it was placed after the muffler.



My hunch is that the first test with the DuraMax showed the greatest gains because the cutout produced the greatest change to exhaust flow. The cutout allowed the exhaust to escape early before having to flow down much of the restrictive exhaust pipe.



On the second one, exhaust was already fairly free-flowing due to the large pipe, and then it had to go through the cat. By then, any advantage of the cutout was largely lost.



To some degree, this applies to the Dodge as well. The cutout was after the muffler. No change in flow restriction until that point.



Since the first DuraMax got the greatest benefit of the cutout, it was able to run on the dyno longer than other two.



That's just my late Friday night, un-thermodynamically educated gut hunch from reading your post twice.



Also, different dynos (brands) will yield different numbers on the same truck. That's from personal experience.



Does my explaination make any sense or did I miss the boat and fall into the water?!



-Jay

 

[Deezul1]

I wonder if the fact that the Dura Max was modified would account for the HP gain/EGT drop because it required better exhaust flow than stock because of increased fueling. The stockers may have pretty good exhaust systems on them from the factory but are engineered to work effectively with stock systems. We commonly go straight pipe with these trucks for better spool up and EGT reduction but EGT reduction isnt needed on stock trucks as they dont fuel enough to get into the danger levels which is evident by the fact that no EGT gauge or warning system is supplied from the factory. Even though it costs more money to include this gauge, it would reduce warranty claims on cooked engines somewhat.

So a modified engine could benefit from your product more than a stocker.

 

[RKohn]

I've gotta show this to one of the guys at work

"DuraMax... ... . dyno test... . chip set at level 3 (90 hp ???)... . 289 rwhp"





:-laf :-laf :-laf

 

[Street Pro]

Many thanks to all of you --- I think we understand what you all are saying -- and the next time we spend $ for Dyno work, we will be ready to do it properly and pick someone well quallified to test Light Duty Diesel trucks, not 18 wheelers. THANKS AGAIN, you have been a great help!

 

[Turbo Thom]

JGK... ..... The bypass at Jeffs shop was installed in front of the muffler. Is is supposed to bypass the muffler and re-enter behind the muffler. What Matt did was remove the cat and with the by-pass, dump the exhaust with about 10 inches of exhaust pipe. So he has a muffler exhaust and a straight exhaust.



There is a post on here where an owner wants to install a stack, and switch back and forth from muffler to stacks. This will work well with that application. I saw what the cost, and was not bad for what it is. Made well to. There is an electric controll in the cab.



That's how it works.



. . Preston. .

 

[JGK]

Preston,



So, let me reiterate to see if I understand...



On the first DuraMax, at the Caterpillar shop, the cut out was installed before the muffler (no cat) - basically turned it into a short, straight-piped, stock exhaust when the cutout was open, right?



On the second DuraMax, the cutout was installed between the cat and the muffler (if any). So in this case, exhaust had to go through the cat either way, correct? If so, the cutout would be less effective, I would think, depending on how much restriction the cat adds.



In the case of the Dodge, I mis-read originally (I said it was late on a Friday night!). I thought it was installed after the muffler, but Street Pro says it bypassed the muffler - installed before, that is. So I would think the first DuraMax and the Dodge would be essentially identical installations. But the DuraMax was chipped and the Dodge was stock. In this case, I would think the DuraMax would see more gains in using the cut out due to the extra fueling causing extra exhaust needing somewhere to go fast.



Am I any closer? Maybe a tentative foot hold on the edge of the boat?



-Jay

 

[Turbo Thom]

You got it. The only reason I said anything at all about the Dodge is because I helped install it and therefor knew how it was installed. On our diesels I really don't expect to see much of any gain in HP . The thing I see is you can so some trick things with the exhaust and possibly lower the egt a little on hard pulls.



Everything just fine.



. . Preston. .

 

[Hohn]

I'm curious as to whether or not the dynos were different. It appears that the "short burst" runs were an intertia-type dyno, like a dynojet. These dynoes work by measuring how fast you can accelerate a drum of known mass. They measure HP and calculate torque.



It appears that the CAT dyno was perhaps a load-type dyno. These also use a drum. But it varies the resistance, unlike the intertia-type. These dynos progressively add more and more resistance until the engine is essentially stalled. They measure torque directly and calculate HP.



Generally, an intertial dyno run will take less time than a load dyno.



It also sounds like the operator of the dyno at the CAT facility didn't know what he was doing. Load dynos are MUCH more susceptible to inconsistent readings, depending on how fast the resistance (load) is increased, and at what RPM.



While I don't believe that HP as a number really means anything, the Dynojet style intertia dyno produces useful info and leaves MUCH less room for operator error.



JMHO



justin