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SRP vs. Stock Dyno

7K views 26 replies 8 participants last post by  Tomasz 
#1 ·
This is a comparison Dyno chart for my Stock vs Softronic/ 4.1 flash mod (stock air filter).

A nice jump around 5500 but looks like a loss on the lower end. Max torque was actually a bit lower.

Next up: V-Flow (if they ever get in stock), Fabspeed headers and Borla exhaust. Will post again with those results.
 
#3 ·
Wait, if the stock run was before the SRP install then there is no reason for the vacuum leak. Right?

Not to go off topic, would be great to have a list of all the possible ways that once could screw up a SRP install. How can I check if I do or do not have a vacuum leak from one of the vacuum lines? When the engine is running, I hear quite a bit of hissing, but I think that is normal. Secondary air pump is for sure loud.

Scott? Maybe this is worth a FAQ?

Tomasz
 
#4 ·
Thanks Mike. Are you willing to test FabSpeed headers separately of Borla? Glad you have a baseline, although it does look little weird.
 
#7 · (Edited)
Hello,

I noticed the dyno yesterday and was going to make a post however I had thought it was just another dyno gone wrong. I think that everyone should should save some money and stop with all the dyno runs. I can go on and on as to how they are all either skewed by Vendor, Op's that do not know what they are doing etc, etc, etc. I have about 40 on the SRP and they are all different. Some are what I would expect and others not close .....

This dyno does show a very abnormal fluctuation around 5200 rpm . This is either from one of two things. The problem also applies to the apparent earlier run of the car on the dyno. The resonance flap is actuated in this range and it is possible that the unit is defective. Defective being that the flap is not fully opening and closing properly and is damaged. The other is that the dyno is experiencing problems in this range.

Best Regards,
Scott Slauson
 
#9 ·
...The resonance flap is actuated in this range and it is possible that the unit is defective...
Scott,
Thanks for your feedback. My posting was not meant as a slam on the SRP. I still feel that it was a very worthwhile modification. I just posted what was recorded and really appreciate any feedback as to the results. Maybe the dyno was off and maybe there is something not quite right with my CS. That is the information that is valuable to me. Any information that I can get on how to determine if this is true would be greatly appreciated.
 
#11 ·
Gator,
Thanks for the info. I will pull the resonance flap section to see if I can tell if it is fouled/damaged in any way.

I changed the SAE smoothing to 5 on this plot (was @ 2 ). Does that remove the jaggedness you refer to or do you still see it as a bit abnormal?
 
#13 ·
Ok.. I took a look at the resonance flap and could not see any problems (external damage). I cleaned out the tube as it did have some gummy oil residue. It may be an internal problem or maybe it is just a dyno abnormality.

Either way, while I was in the engine compartment, I decided to pull the air filter and inspect it. I haven't checked it since I got the car because I am planning to install a V-Flow (on order.. been waiting 2 months). The filter was VERY dirty. I removed it and knocked out the dust (A lot came out) then vacuumed it out as best I could.

Results: OMG my car sounds like a different car. I could feel the power difference but the sound was the most evident change (more throaty and loud even at lower RPMs).

I don't think the air filter could have caused the dip @ 5200 but it does explain how the SRP mod came in a bit lower than expected. I'm not sure I agree with Scott that we should stop doing dyno runs but I think we should realize every car is different and that it is not always evident what the bottleneck in our search for more power is. In my case it led me to search further for a possible issue (and I'm pretty sure I found one).

Thanks again for all the feedback from everyone.
 
#14 ·
Either way, while I was in the engine compartment, I decided to pull the air filter and inspect it. I haven't checked it since I got the car because I am planning to install a V-Flow (on order.. been waiting 2 months). The filter was VERY dirty. I removed it and knocked out the dust (A lot came out) then vacuumed it out as best I could.

Results: OMG my car sounds like a different car. I could feel the power difference but the sound was the most evident change (more throaty and loud even at lower RPMs).
You just reduced your satisfaction level with the V-Flow. As you would have gotten the same result or hopefully) better after installing V-Flow, and you would have attributed it all to it. Just teasing a bit here.
 
#15 ·
Scott - no dyno, no G-Timer, no Durametric time logging... what do you recommend? I know that I can always compare two cars by racing them on a highway. Lets say a 3rd gear run from 50 to 100.

But how do I take a baseline, modify, and measure again to see the effect on my car? I know dynoes are not perfect, but they should be indicative and directionally correct. I rather by approximately right than definitely wrong.

Tomaasz
 
#17 · (Edited)
Tomasz with all respect they all have their limitations and especially when done wrong .
Durametric does not check quick enough for times to be accurate.

Dynos are all over the board and especially when not done correctly etc. This is most of all that I have seen. The ones done by other dealers are inherently skewed for the benefit of them trying to sell their product. Others are done on different days with different conditions not alloted for, Etc Etc Etc.

Should you want to do a timer test then perform it at a range that the car would test at correctly or for an expected range of improvement.

We all know that the SRP by itself has a loss below 3500 and then gains above that. I think this has been stated many times before so your testing does not make any sense in saying it should have gained below that and does not now. :crazy: This is simply because the diverter valve in the stock Plenum is normally closed until then and opens at that range. So basically a dyno that does not show a cross in HP and Torque at that range is not accurate when just the SRP was installed. This would be by the running of the car and many other variables that I do not have the time to list.

Now add the exhaust to it and the gains will be through the entire range. Basically more in more out. This would apply to ANY larger TB and the gains get worse on the lower end the larger the TB. A larger TB being from stock and the given flow of an engine. I could have used a 82mm and it would bolt on however it would be even worse below 3500 and only gain more with a complete exhaust from headers to muffler. The gains then would only be about 7hp at 6500 or so with my software. Bigger is not always better unless for bragging to people who do not know the difference.

I'm forever getting emails from people that had dynos and it doesn't look correct. The first question that I ask is who did it and the dyno type. Many I have told since I'm familiar with the companies that did the testing and tend to be bias to go try another. I do not specify any. They pic another dyno and they get totally different results and are happy. Some test improper installed kits, cars with bad filters, tires inflated incorrectly, cars not secured down correctly and on and on and on.



Scott
 
#18 ·
Among many assignments I got to be manager of a research lab for awhile at a major oil company where we checked competitor oil products. I learned that dyno results are only as good as the person running them and without very precise standards will give any result a person wishes. Their best use for the amateur is to attempt to compare before and after modification results (not to compare one car vs another at different times, conditions, operators and so forth). Using the firm selling the mod who has skin in the game is foolish as most of recognize.
 
#24 ·
Sorry for the late response. I was on vacation last week.

I actually think the weakness in the dyno was due to a very dirty air filter. I didn't have it re-dyno'd after I replaced the air filter but the difference was pretty noticeable.

The dip in the dyno is evident in other runs with other Caymans (the shop had dyno'd 2 other Caymans) so I didn't look any further for an issue with my car. Since then I have installed Fabspeed headers and Borla exhaust. I am planning on taking it back for a final dyno to see what the entire (intake/exhaust) system can do.
 
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