380hp? Well....
#1
380hp? Well....
From another Forum, but the print out from the rolling road makes for interesting reading.
F-type V6 S BHP - PistonHeads
F-type V6 S BHP - PistonHeads
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DJS (06-21-2015)
#2
So many things could contribute to this...
I've had my car on 3 different dyno's and had variations of 40rwhp... which could be 50hp at the crank if you take a rule of thumb for drivetrain losses.
The guy himself is saying he doesn't understand much about dyno's, so good luck to the PH guys getting answers.
I've had my car on 3 different dyno's and had variations of 40rwhp... which could be 50hp at the crank if you take a rule of thumb for drivetrain losses.
The guy himself is saying he doesn't understand much about dyno's, so good luck to the PH guys getting answers.
#3
#4
#6
From another Forum, but the print out from the rolling road makes for interesting reading.
F-type V6 S BHP - PistonHeads
F-type V6 S BHP - PistonHeads
Wonder what the 'R' actually puts out on a dyno.
Lawrence.
#8
#9
if it were a normally aspirated engine, I would conclude a different cam profile should resolve this. However, forced induction should not suffer from that problem unless the super charger is undersized or the mapping is just plain crappy. If anyone knows which model Eaton is being used, I could check the performance curve of the SC to confirm whether it is to blame. If the SC is undersized, a reduction pulley will just bring on the power drop-off at a lower engine speed.
#10
if it were a normally aspirated engine, I would conclude a different cam profile should resolve this. However, forced induction should not suffer from that problem unless the super charger is undersized or the mapping is just plain crappy. If anyone knows which model Eaton is being used, I could check the performance curve of the SC to confirm whether it is to blame. If the SC is undersized, a reduction pulley will just bring on the power drop-off at a lower engine speed.
Where I am, premium fuel is rated at 91 and we have seasonal blends. My current car (Volvo C30 T5 with Polestar optimized tune) expects premium, although their notion of premium is probably 93, perhaps even more. The engine management system adjusts for lower ratings, leading to reduced performance.
#11
I've noticed the same, and short shift at about 6K RPM because of this. Interesting to see this reflected on paper (and validate our butt dynos).
#13
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Unless I missed some clarification, the dyno sheet and numbers seems to indicate rear wheel horsepower only and not net HP at the flywheel, the latter being what all OEMs use as advertised numbers.
If so, the 340 RWHP is pretty much on target if an approx 10% loss is allowed from the flywheel.
If so, the 340 RWHP is pretty much on target if an approx 10% loss is allowed from the flywheel.
#15
it is a dual drum dyno, which usually shows a lower rwhp output (also pending on how the car is strapped down).
The dyno slip shows the rwhp in green (so 293 ish rwhp), the red line is an estimated engine hp figure (ie the 335 and 340 bhp).
I have seen some 300 rwhp figures on these type of dynos for stock 4.2 XKRs with advertised 400 bhp.
The dyno slip shows the rwhp in green (so 293 ish rwhp), the red line is an estimated engine hp figure (ie the 335 and 340 bhp).
I have seen some 300 rwhp figures on these type of dynos for stock 4.2 XKRs with advertised 400 bhp.
Last edited by avos; 06-22-2015 at 01:16 PM.
#16
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#17
I've never owned a supercharged vehicle, but have some experience with turbocharged ones. For that type of forced induction, the power dropoff could be caused by the ECU detecting detonation and adjusting timing and boost pressure accordingly.
Where I am, premium fuel is rated at 91 and we have seasonal blends. My current car (Volvo C30 T5 with Polestar optimized tune) expects premium, although their notion of premium is probably 93, perhaps even more. The engine management system adjusts for lower ratings, leading to reduced performance.
Where I am, premium fuel is rated at 91 and we have seasonal blends. My current car (Volvo C30 T5 with Polestar optimized tune) expects premium, although their notion of premium is probably 93, perhaps even more. The engine management system adjusts for lower ratings, leading to reduced performance.
#19
Perhaps the discrepancy is due to the U.K.'s higher octane fuels? Jaguar's performance claims for this engine could be based on the 98 RON fuel available in the U.K., and the crap 91 octane (93 if you're lucky) we have here in the States accounts for the drop in power.
Although a 40hp decrease due to octane seems unlikely, it is an FI engine and would have to dial back boost to avoid detonation.
Although a 40hp decrease due to octane seems unlikely, it is an FI engine and would have to dial back boost to avoid detonation.
#20
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Perhaps the discrepancy is due to the U.K.'s higher octane fuels? Jaguar's performance claims for this engine could be based on the 98 RON fuel available in the U.K., and the crap 91 octane (93 if you're lucky) we have here in the States accounts for the drop in power.
Although a 40hp decrease due to octane seems unlikely, it is an FI engine and would have to dial back boost to avoid detonation.
Although a 40hp decrease due to octane seems unlikely, it is an FI engine and would have to dial back boost to avoid detonation.
How would an engine 'dial back boost'?