In-Depth testing of 60mm Dual vs. 70mm Single
01-10-2011, 12:44 PM
#41
Former Sponsor
Thread Starter
Originally Posted by dan_uk,Jan 10 2011, 02:38 PM
you think if I put the stock exhaust back on and got it re-tuned it'd make more power?
When we had out club dyno day, most of the cars made their best numbers on the 3rd pull, but some made their best on the 1st or second. I think I needed a 4th or 5 pull, since my FlashPro datalogs from the Dynojet pulls show that my AFR was 12.2 or richer on all 3 pulls, but was always 12.4 or higher when I do soft dyno pulls.
01-10-2011, 01:45 PM
#42
well it definitely affects the AFR's up top but that gave me a thought - maybe the stock exhaust with stock mufflers just gets restrictive up top?
maybe your mufflers flow better at higher rpm's than stock and that might explain why ap1's seem to do better with 70mm?
out of 4 odd dyno sessions the car was always rich up top over 8000rpm's then with the 70mm it wasn't
maybe your mufflers flow better at higher rpm's than stock and that might explain why ap1's seem to do better with 70mm?
out of 4 odd dyno sessions the car was always rich up top over 8000rpm's then with the 70mm it wasn't
01-10-2011, 02:14 PM
#43
Originally Posted by gernby,Jan 10 2011, 01:34 PM
I wasn't going to answer this question here, since I want to keep the arguments about the soft dyno over in its own thread. However, I think this question is relevant enough to this thread to go ahead and aswer it.
First, the soft dyno is just as "real" as any dyno. It's just not a "conventional" dyno that people are used to talking about. My education is in engineering, and so was my career until about 4 years ago when I went over in to software development full time. The science behind a DynoJet is pretty basic, and is easy to duplicate using a datalog with high sample rate. Basically, a DynoJet measures output in the same way that my soft dyno does.
Now to answer your question. The reasons why I didn't do the testing on a conventional dyno are:
1) I don't own a conventional dyno, and would NEVER conduct tests like this if they cost me $100 / hour
2) Conventional dynos don't account for changes in weight
2) Conventional dynos don't account for heat soak or IAT's
3) Conventional dynos don't account for air flowing into the front of the car at 80 MPH
4) It's impossible to use a conventional dyno to test a car that is TRULY at normal operating temp, as if it had just come off the highway after cruising at 60 MPH for 30 minutes.
First, the soft dyno is just as "real" as any dyno. It's just not a "conventional" dyno that people are used to talking about. My education is in engineering, and so was my career until about 4 years ago when I went over in to software development full time. The science behind a DynoJet is pretty basic, and is easy to duplicate using a datalog with high sample rate. Basically, a DynoJet measures output in the same way that my soft dyno does.
Now to answer your question. The reasons why I didn't do the testing on a conventional dyno are:
1) I don't own a conventional dyno, and would NEVER conduct tests like this if they cost me $100 / hour
2) Conventional dynos don't account for changes in weight
2) Conventional dynos don't account for heat soak or IAT's
3) Conventional dynos don't account for air flowing into the front of the car at 80 MPH
4) It's impossible to use a conventional dyno to test a car that is TRULY at normal operating temp, as if it had just come off the highway after cruising at 60 MPH for 30 minutes.
01-10-2011, 06:03 PM
#45
Gernby,
I really like your posts and you've been on here a long time. You have a huge amount of knowledge under your belt.
So with that in mind, I'm just going to say that there's no way a 60mm stock exhaust with different mufflers makes as much power as something like my 75mm HKS exhaust or the new Berk 75mm exhaust.
I'd really like to see a well-executed dyno run comparing your muffler/60mm with 60mm test pipe combo vs the HKS/Berk 3" with a 3" test pipe. I would guess the HKS/Berk put down 6-10 whp more than the 60mm combo. Just my thoughts.
I really like your posts and you've been on here a long time. You have a huge amount of knowledge under your belt.
So with that in mind, I'm just going to say that there's no way a 60mm stock exhaust with different mufflers makes as much power as something like my 75mm HKS exhaust or the new Berk 75mm exhaust.
I'd really like to see a well-executed dyno run comparing your muffler/60mm with 60mm test pipe combo vs the HKS/Berk 3" with a 3" test pipe. I would guess the HKS/Berk put down 6-10 whp more than the 60mm combo. Just my thoughts.
01-10-2011, 06:50 PM
#46
Registered User
^Thank you for that. I was beginning to think that I was the only one.
A 60mm pipe will only flow so much. A 75mm will flow more guaranteed. But if you have a pipe that goes 60mm then goes up to 75mm, the end result is going to be the flow of the 60mm pipe, not the 75mm. Hence why you didn't gain much with your 70mm.
A 60mm pipe will only flow so much. A 75mm will flow more guaranteed. But if you have a pipe that goes 60mm then goes up to 75mm, the end result is going to be the flow of the 60mm pipe, not the 75mm. Hence why you didn't gain much with your 70mm.
01-11-2011, 03:04 AM
#48
Registered User
Originally Posted by H22toF20,Jan 10 2011, 07:50 PM
^Thank you for that. I was beginning to think that I was the only one.
A 60mm pipe will only flow so much. A 75mm will flow more guaranteed. But if you have a pipe that goes 60mm then goes up to 75mm, the end result is going to be the flow of the 60mm pipe, not the 75mm. Hence why you didn't gain much with your 70mm.
A 60mm pipe will only flow so much. A 75mm will flow more guaranteed. But if you have a pipe that goes 60mm then goes up to 75mm, the end result is going to be the flow of the 60mm pipe, not the 75mm. Hence why you didn't gain much with your 70mm.
01-11-2011, 07:20 AM
#49
Former Sponsor
Thread Starter
Originally Posted by b.r.i.a.n.,Jan 10 2011, 06:14 PM
LOL. we've already gone over this on your other thread. LOL at dynos not taking into account heak soak or iat's. trust me if you've actually worked on a dyno and encountered heat soak or changes in iat you WILL see the changes on the graph.
You didn't even reply about the questions I had regarding your first post in this thread. I'm sure you're a knowledgeable tuner, so why won't you explain your assumption that the 70mm exhaust made no gains because of ignition timing? Why won't you explain how it is that I got very obvious and significant changes in AFR and torque from my PWJDM intake, 60mm test pipe, and T1R header, but NOTHING AT ALL from a 70mm exhaust? I tested each of them individually as well with all stock components, and in combinations with each other. The 70mm exhaust is the ONLY part I've tested that shows virtually no change.
I've never "worked" on a dyno, but I've paid for many, many dyno runs at multiple shops, and have been right there when they were performed. I've never had a run where the car wasn't pulling high IAT's, and the AFR curves have always fluctuated.
You ask me to trust you? Why?
01-11-2011, 07:25 AM
#50
Former Sponsor
Thread Starter
Originally Posted by Disgustipated,Jan 10 2011, 10:03 PM
Gernby,
I really like your posts and you've been on here a long time. You have a huge amount of knowledge under your belt.
So with that in mind, I'm just going to say that there's no way a 60mm stock exhaust with different mufflers makes as much power as something like my 75mm HKS exhaust or the new Berk 75mm exhaust.
I'd really like to see a well-executed dyno run comparing your muffler/60mm with 60mm test pipe combo vs the HKS/Berk 3" with a 3" test pipe. I would guess the HKS/Berk put down 6-10 whp more than the 60mm combo. Just my thoughts.
I really like your posts and you've been on here a long time. You have a huge amount of knowledge under your belt.
So with that in mind, I'm just going to say that there's no way a 60mm stock exhaust with different mufflers makes as much power as something like my 75mm HKS exhaust or the new Berk 75mm exhaust.
I'd really like to see a well-executed dyno run comparing your muffler/60mm with 60mm test pipe combo vs the HKS/Berk 3" with a 3" test pipe. I would guess the HKS/Berk put down 6-10 whp more than the 60mm combo. Just my thoughts.