Disappointing results after performance upgrades-S Type R
Guest
Posts: n/a
Disappointing results after performance upgrades-S Type R
Hi all,
Don't know if this is the correct section but seems a good place to start.
I recently had an ECU remap, modified supercharger pulley, replacement rear boxes and new air filter fitted to my 2007 STR by a well known Jaguar performance specialist, not some back street, fly-by-night tuner. The claimed bhp increase for the pulley was 20 bhp, the ECU remap 25 bhp and a more modest increase from the other bits and pieces. Unfortunately on the day of fitting the rolling road was broken so dyno run couldn't be completed.
However, today I had my car tested on their rolling road and was very disappointed by the results. The rolling road is made by Dyno Dynamics and the best and worst results were 413.6 hp and 399.3 hp at the flywheel. Given the standard car is supposed to produce 395-400 hp you may understand my disappointment. It was explained to me that the Jaguar figures are optimistic and in reality the 4.2 supercharged engines typically produce 360-370 bhp, so the mods have done what is claimed. That didn't sound right to me.
Is this correct or have I wasted my money? Maybe there is something wrong with my car? Was the rolling road faulty?
I'm not an engineer, mechanic or expert so would appreciate your thoughts.
Thanks.
Don't know if this is the correct section but seems a good place to start.
I recently had an ECU remap, modified supercharger pulley, replacement rear boxes and new air filter fitted to my 2007 STR by a well known Jaguar performance specialist, not some back street, fly-by-night tuner. The claimed bhp increase for the pulley was 20 bhp, the ECU remap 25 bhp and a more modest increase from the other bits and pieces. Unfortunately on the day of fitting the rolling road was broken so dyno run couldn't be completed.
However, today I had my car tested on their rolling road and was very disappointed by the results. The rolling road is made by Dyno Dynamics and the best and worst results were 413.6 hp and 399.3 hp at the flywheel. Given the standard car is supposed to produce 395-400 hp you may understand my disappointment. It was explained to me that the Jaguar figures are optimistic and in reality the 4.2 supercharged engines typically produce 360-370 bhp, so the mods have done what is claimed. That didn't sound right to me.
Is this correct or have I wasted my money? Maybe there is something wrong with my car? Was the rolling road faulty?
I'm not an engineer, mechanic or expert so would appreciate your thoughts.
Thanks.
Veteran Member
Joined: May 2010
Posts: 1,445
Likes: 218
From: Atlanta, GA
Hi all,
Don't know if this is the correct section but seems a good place to start.
I recently had an ECU remap, modified supercharger pulley, replacement rear boxes and new air filter fitted to my 2007 STR by a well known Jaguar performance specialist, not some back street, fly-by-night tuner. The claimed bhp increase for the pulley was 20 bhp, the ECU remap 25 bhp and a more modest increase from the other bits and pieces. Unfortunately on the day of fitting the rolling road was broken so dyno run couldn't be completed.
However, today I had my car tested on their rolling road and was very disappointed by the results. The rolling road is made by Dyno Dynamics and the best and worst results were 413.6 hp and 399.3 hp at the flywheel. Given the standard car is supposed to produce 395-400 hp you may understand my disappointment. It was explained to me that the Jaguar figures are optimistic and in reality the 4.2 supercharged engines typically produce 360-370 bhp, so the mods have done what is claimed. That didn't sound right to me.
Is this correct or have I wasted my money? Maybe there is something wrong with my car? Was the rolling road faulty?
I'm not an engineer, mechanic or expert so would appreciate your thoughts.
Thanks.
Don't know if this is the correct section but seems a good place to start.
I recently had an ECU remap, modified supercharger pulley, replacement rear boxes and new air filter fitted to my 2007 STR by a well known Jaguar performance specialist, not some back street, fly-by-night tuner. The claimed bhp increase for the pulley was 20 bhp, the ECU remap 25 bhp and a more modest increase from the other bits and pieces. Unfortunately on the day of fitting the rolling road was broken so dyno run couldn't be completed.
However, today I had my car tested on their rolling road and was very disappointed by the results. The rolling road is made by Dyno Dynamics and the best and worst results were 413.6 hp and 399.3 hp at the flywheel. Given the standard car is supposed to produce 395-400 hp you may understand my disappointment. It was explained to me that the Jaguar figures are optimistic and in reality the 4.2 supercharged engines typically produce 360-370 bhp, so the mods have done what is claimed. That didn't sound right to me.
Is this correct or have I wasted my money? Maybe there is something wrong with my car? Was the rolling road faulty?
I'm not an engineer, mechanic or expert so would appreciate your thoughts.
Thanks.
Veteran Member
Joined: Feb 2010
Posts: 1,080
Likes: 43
From: Carrollton TX
take for example mine. look at my Mafioso's Thread! I have my baseline numbers there.
Without a baseline there is no way to know what the modifications did.
Perhaps you got a monday or a friday car?
Without knowing before only the after it puts you in this position.
Did they give you a print out? if you can post it up we can analyse that help out.
Without a baseline there is no way to know what the modifications did.
Perhaps you got a monday or a friday car?
Without knowing before only the after it puts you in this position.
Did they give you a print out? if you can post it up we can analyse that help out.
Last edited by Mafioso; Oct 11, 2010 at 02:40 PM.
FIRST I use a dyno dynamics when I do wheel hp numbers and it gives wheel hp and is VERY conservative (many say realistic) thats why its called the "heart breaker" too. Number are just that, without a graph of before and after you dont know if your car was even producing the numbers that are stock before. Theres too much that affects power output and numbers can be changed by a dyno operator to read higher or lower by changing evironmental conditions etc.....Personally I wouldnt spend any money on anything but AVOS's twinscrew kit. Yes its alot of moeny. yes itll be a huge smile every time you touch the gas pedal. Yes it have me even thinking about selling my Jag and getting a newer sc car just so I could do this swap,
Joined: Oct 2009
Posts: 11,057
Likes: 2,272
From: Perth Ontario Canada
Your dyno numbers are rear wheel horsepower. Jaguar's numbers (like all OEMs) are at the flywheel. Big difference. I think you did very well with the numbers quoted.
Trending Topics
Veteran Member
Joined: May 2009
Posts: 27,519
Likes: 4,910
From: Yorkshire, England
Something seems a bit wrong here. They can measure rwhp but I don't see how they can measure flywheel hp. So, either those are rwhp (but they seem too big) or they've estimated flywheel hp. If the latter, what were the rwhp figures?
Veteran Member
Joined: Nov 2009
Posts: 5,084
Likes: 432
From: NY
Alchris, I bet you my left hi-flo cat that you're reading the dyno sheet incorrectly and now have 413 hp at the rear wheels. Stock 07 STR's develop 400 hp at the crank; 350 hp at the wheels. Congratulations! You just gained 63 hp fella. Now pop on hi-flo cats, x-pipe, and 2 1/2" pipe down the pipe line and you'll earn another 25 hp for a total of 475 crank hp or 438 hp at the wheels.
Veteran Member
Joined: Apr 2009
Posts: 1,409
Likes: 20
From: Canada
Agreed. No way he got a 63 rwhp increase. That would be like a 100 increase at the crank...
Veteran Member
Joined: May 2010
Posts: 1,445
Likes: 218
From: Atlanta, GA
Might not run to good he titled the post disappointing results. I'm not really a numbers guy. I could care less how much hp I have as long as I can feel it I'm good and as long as it throws me back in my seat and makes me go holy $&!* then I'm good. I do get curious about what it will run at the track. I just found out there is a dyno right down the road from me might call and if its not too much just run down there and get a baseline just for S's and G's.
Veteran Member
Joined: Feb 2010
Posts: 1,080
Likes: 43
From: Carrollton TX
Alchris, I bet you my left hi-flo cat that you're reading the dyno sheet incorrectly and now have 413 hp at the rear wheels. Stock 07 STR's develop 400 hp at the crank; 350 hp at the wheels. Congratulations! You just gained 63 hp fella. Now pop on hi-flo cats, x-pipe, and 2 1/2" pipe down the pipe line and you'll earn another 25 hp for a total of 475 crank hp or 438 hp at the wheels.
we have gravity to deal with. 20% of 400 is only 320whp.
Senior Member
Joined: Jun 2010
Posts: 153
Likes: 5
From: Seattle
I heard that after they've given it the berries they let it run down (not using the brakes to slow the wheels to a stop) and this calculates the mechanical drag. Then with a whizzy math formula they can determine the flywheel hp.
Veteran Member
Joined: May 2009
Posts: 27,519
Likes: 4,910
From: Yorkshire, England
I'm pretty sure they can measure flywheel hp ratings. I very well could be mistaken though.
I heard that after they've given it the berries they let it run down (not using the brakes to slow the wheels to a stop) and this calculates the mechanical drag. Then with a whizzy math formula they can determine the flywheel hp.
I heard that after they've given it the berries they let it run down (not using the brakes to slow the wheels to a stop) and this calculates the mechanical drag. Then with a whizzy math formula they can determine the flywheel hp.
Veteran Member
Joined: Nov 2009
Posts: 5,084
Likes: 432
From: NY
Hey boys, let's go back to the beginning of this thread when we briefly discussed disparing dynos, conditions, even the skill of their operators. Let's go back even further to Riski's and others 340+ RWH dyno-runs performed on their bone stock STR's. I can understand 50 hp lost to drivetrain parasites, but not 70+hp. In earlier threads discussing STR factory and aftermarket dyno results, we agreed that an otherwise bone-stock STR puts nearly 340 hp to the wheels. Now an overly conservative dyno-run which may have been flawed from the git-go, clocks in an STR at 317 RWH? 317 RWH won't produce the road performance clocked on a stock STR. I believe Alchris needs to either check his car for issues, i.e was DSC disengaged? Was adaptive learning cleared? Fresh fuel and air filter? Does he have an x-pipe, 2 1/2" pipe, and delete stock resonator? Perform another dyno-run on another dyno or under different conditions. A properly tuned STR with an exhaust, pulley, and ECU mod should gain 50+ hp or at least 375+ RWH.
