Pritchard

Dyno Day / Results from an F

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sorry for dropping a post into your neck of the woods... but i had my LC500 on the dyno today... didnt go so well.
in fact, my graph was waaay different (in its curve) to what it should be, or what i have seen posted elsewhere.
 

torque was a little down on advertised figures, but made peak torque at the right rpm range (4,700). this is fine.
BHP however, peaked at 6,100 rpm (1000 rpm early) and then dropped off very quickly. as a result my peak power is about 50-70bhp down, depending on what numbers you want to use.

i was wondering - the 'F' has the same V8 engine, right? would anyone want to join me on a dyno-day? i really need a back to back run with someone so i had a case to take to Lexus to have them look at this objectively.

ill get the graph up when i can. But the figures (torque looks fine, its just the hp drop off at the top).
@ Wheels:
355whp @ 6,200rpm

447Nm @ 4,700rpm


estimated at Fly:
408bhp
514Nm (379lb-ft)

horsepower has dropped off to about estimated 350bhp by 6,900 rpm, which is over 100bhp down on where it should be at this rpm.

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Do you by any chance know the make of dyno? the reason I ask is that back in the days when my RX7 was being tuned/rebuilt/costing a fortune the guys who did it had a Dyno Dynamics rolling road that they said really underated the power output. Whereas I know many overestimate the power.

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1 hour ago, Pritchard said:

i had a case to take to Lexus to have them look at this objectively.

Sooooo many variables to even remotely have a chance of taking a 'case' to Lexus I'm afraid. Could I ask does the dyno run make any difference to you/ the love of the car and just interested to know exactly what case you would make to Lexus (not a salty post btw, just genuinely intrigued) 🙂 

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Dyno runs are great for before and after comparison figures demonstrating any increased output due to tuning work but as a stand alone measurement, one would need to show calibration certs for the dyno for the figures to carry any weight. 

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ive been on and off dynos many times of many years of tuning and playing with my cars. I am not fixated on the number (hp). my concern was the curve, its nothing like any other i have seen for this engine. it looks to me like a typical static cam phasing that hit its max airflow, and the rpm range beyond that no longer produces the torque. but i would imagine any problems with the vvt mechanism would be throwing CELs.
its just a reference to how the graph looks. not really a theory.

so, irregardless of what dyno i was on today, its brand or calibration... i was hoping someone might fancy a dyno run, or maybe theres a dyno-day you guys might be organising where i could pop along? that would be the only way i would know if my car has a problem (couldnt give two stick wags to whether the dyno was accurate in its numbers). 🙂

 

thanks

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I’d be up for a dyno run. Mines a GSF, so same engine, but yours has a slightly different intake I believe? I’m around the Portsmouth area. 
 

Have you noticed your car has recently lost power, or has it always felt slower than it should? If you felt everything was all right before, it might be worth taking it for a run on a different dyno? 

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On a related point but which might be relevant, I had a problem with my LC500 after I had had it for about 10 months. It suddenly felt down on power, the "crackle" from the exhaust had disappeared and the transition at about 4000rpm was not happening. My dealer checked it out and there was no apparent problem but something had changed. However, after a few refuelling cycles with high octane unleaded from a different garage, the problem went away. My diagnosis - a duff lot of fuel at my local service station which does not have a high turnover in Super 98+ fuel. the care ECU adjusts itself to fuel quality.

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as others have said there are a lot of factors to take into consideration, also bear in mind that you are more than likely on winter fuel now.

 

Can you post the graph?

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Also cold weather doesn't help. 

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1 minute ago, Arqum said:

Also cold weather doesn't help. 

Cold weather does help as the air is more dense, but correction values on dynos become less accurate the more you move from typical ambient temps

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12 hours ago, mrfunex said:

I’d be up for a dyno run. Mines a GSF, so same engine, but yours has a slightly different intake I believe? I’m around the Portsmouth area. 
 

Have you noticed your car has recently lost power, or has it always felt slower than it should? If you felt everything was all right before, it might be worth taking it for a run on a different dyno? 

yes please 🙂 i am in Kent. happy to come in your direction if youve got a recommended dyno? you around in Jan sometime?
no car doesnt feel any different, but then on the roads i havent given it full boot in the last month or so since the temp dropped.

 

4 hours ago, malcolmw said:

On a related point but which might be relevant, I had a problem with my LC500 after I had had it for about 10 months. It suddenly felt down on power, the "crackle" from the exhaust had disappeared and the transition at about 4000rpm was not happening. My dealer checked it out and there was no apparent problem but something had changed. However, after a few refuelling cycles with high octane unleaded from a different garage, the problem went away. My diagnosis - a duff lot of fuel at my local service station which does not have a high turnover in Super 98+ fuel. the care ECU adjusts itself to fuel quality.

thanks, noted 🙂 i always use super, with the 12.3:1 compression i would image a 95ron fill up will cost you some ponies.

 

1 hour ago, Twellsie said:

as others have said there are a lot of factors to take into consideration, also bear in mind that you are more than likely on winter fuel now.

 

Can you post the graph?

ive taken a pic scan of the graph, but the lines are thin 😞 ive messaged the dyno guy yesterday asking for an emailed copy, rather than from his printer. waiting for that....

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There’s been a couple of threads on the club Lexus site talking about dyno runs on the f cars. 
https://www.clublexus.com/forums/gs-f-2016-present/887291-gsf-dyno-questions.html

this one suggests that on the GSF the runs to give the most representative results should be in in 6th gear.  May be a similar situation with the LC.

 

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I am not sure if changing modes from Normal to Sport or Sport + actually affects the engine mapping (i.e. power output) or just the gear change points. This may bear on the gear selection issue mentioned.

On the fuel question, does the ubiquitous use of E5 (or now even E10) in high octane fuel reduce the power from the claimed output? Is the output claim based on 100% oil based petrol? 

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2 hours ago, Killysprint said:

There’s been a couple of threads on the club Lexus site talking about dyno runs on the f cars. 
https://www.clublexus.com/forums/gs-f-2016-present/887291-gsf-dyno-questions.html

this one suggests that on the GSF the runs to give the most representative results should be in in 6th gear.  May be a similar situation with the LC.

correct 6th gear is 1:1 in our cars, what gear was the car run in?

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1 hour ago, malcolmw said:

I am not sure if changing modes from Normal to Sport or Sport + actually affects the engine mapping (i.e. power output) or just the gear change points. This may bear on the gear selection issue mentioned.

On the fuel question, does the ubiquitous use of E5 (or now even E10) in high octane fuel reduce the power from the claimed output? Is the output claim based on 100% oil based petrol? 

if anything I would believe the addition of ethanol at the same RON would increase performance, ethanol has a lower flash point than petrol meaning that it would reduce the likelihood of preignition meaning you could further advance the ignition

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5 hours ago, Killysprint said:

There’s been a couple of threads on the club Lexus site talking about dyno runs on the f cars. 
https://www.clublexus.com/forums/gs-f-2016-present/887291-gsf-dyno-questions.html

this one suggests that on the GSF the runs to give the most representative results should be in in 6th gear.  May be a similar situation with the LC.

 

 

2 hours ago, Twellsie said:

correct 6th gear is 1:1 in our cars, what gear was the car run in?

for the LC 10-speed 1:1 in in its 7th. but 1:1 is only the 7th gear itself, the final drive and wheels obv change the actual gearing, and the final drive is a very long 2.9##

but, the dyno was done tried in 4t, 5th and 6th. (6th is a top speed of about 177mph. 7th wouldve hit the dynos speed limiter at 200+, so wasnt attempted.). 4th was a waste of time as the run was too short. after corrections, 5th and 6th looked the same.

 

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I think it will become clearer once you post a pic of the Dyno graph. If your peak torque figure is correct (or close to what Lexus states) and it peaks at the correct rpm, then theoretically the HP should be also close to the Lexus claim. Either the Dyno isn’t set up correctly, or the car has a slight restriction at the top end (could be fueling related - does the graph show the AFR trace?). Another factor could be how the car is set up to run on the dynamometer, for example does the car have a “Dyno mode” similar to AMG Merc cars, that it should be put in to run on the Dyno?

i agree with your logic though of getting another similar engined car on the Dyno to compare. 

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got it -
these are estimated at fly, obviously. the highest WHP was 355whp

 

dynoresult.thumb.jpg.1de9007cb50b4b3e9d3b980522f43df7.jpg

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Peak power for the GSF should be 471bhp at 7100rpm and 391lb ft from 4800 to 5600rpm. 

looking at the graphs above - the dyno run looks like the throttle was shut at just over 6000rpm, so not surprising power is down.  the 500nm is about 370 lb ft, torque peak / plateau is where it’s supposed to be, but a little low

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On 11/30/2019 at 11:29 PM, Pritchard said:

ive been on and off dynos many times of many years of tuning and playing with my cars. I am not fixated on the number (hp). my concern was the curve, its nothing like any other i have seen for this engine. it looks to me like a typical static cam phasing that hit its max airflow, and the rpm range beyond that no longer produces the torque. but i would imagine any problems with the vvt mechanism would be throwing CELs.
its just a reference to how the graph looks. not really a theory.

so, irregardless of what dyno i was on today, its brand or calibration... i was hoping someone might fancy a dyno run, or maybe theres a dyno-day you guys might be organising where i could pop along? that would be the only way i would know if my car has a problem (couldnt give two stick wags to whether the dyno was accurate in its numbers). 🙂

 

thanks

Yours will have exhaust filters? The curves are different for these cars than cars without the filters.

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