Chimaera Factory BHP
Discussion
I am trying to find out how much BHP an ex-factory unmodified Chimaera really produced ?
Seems to be a tough question ...... here is the result we all know from Wiki (and probably all dream about).
I also have a copy of the EEC approval certificate which interestingly enough shows the following at section 3.2.1.8.....
If the calculator I'm using is correct this would indicate
a 4.0 (154Kwatt) 206BHP
a 4.5 (175Kwatt) 235BHP
a 5.0 (182Kwatt) 244BHP.
None of this is clear about wheels or flywheel.
I have read many posts with some amazing figures which I would really love to get to with my little old 450 without having to go through significant tuning mods.
Before hot cams, exhausts, mapable ECU's etc.
I really don't know what would be a reasonable comparison for a healthy unmodified engine
Anyone out there with some comparative insight, unmodified RR data or other info ?
Seems to be a tough question ...... here is the result we all know from Wiki (and probably all dream about).
I also have a copy of the EEC approval certificate which interestingly enough shows the following at section 3.2.1.8.....
If the calculator I'm using is correct this would indicate
a 4.0 (154Kwatt) 206BHP
a 4.5 (175Kwatt) 235BHP
a 5.0 (182Kwatt) 244BHP.
None of this is clear about wheels or flywheel.
I have read many posts with some amazing figures which I would really love to get to with my little old 450 without having to go through significant tuning mods.
Before hot cams, exhausts, mapable ECU's etc.
I really don't know what would be a reasonable comparison for a healthy unmodified engine
Anyone out there with some comparative insight, unmodified RR data or other info ?
I think the calculator your using is at the wheels and probably fairly accurate
If you add 17% for drive train loss those figures would be about right for a standard car. Anything over 285 at the fly for a 450 will be a fast motor.
Mine is a standard 450 with just new rings in original honed bores and no other engine mods other than Powers rebuilding it using there 885 cam, but does have Powers supplied/fitted and mapped MBE ECU and that made 299 bhp at the fly and 350 ft of torque at 4000 revs.
So a non rebuilt engine with a used cam I’d take 20-25 off those numbers and go from there.
If you add 17% for drive train loss those figures would be about right for a standard car. Anything over 285 at the fly for a 450 will be a fast motor.
Mine is a standard 450 with just new rings in original honed bores and no other engine mods other than Powers rebuilding it using there 885 cam, but does have Powers supplied/fitted and mapped MBE ECU and that made 299 bhp at the fly and 350 ft of torque at 4000 revs.
So a non rebuilt engine with a used cam I’d take 20-25 off those numbers and go from there.
TV8 said:
Not sure what you mean by ex-factory? My 1st car was a very early 4.0 one and had the 240 bhp and 270lb ft it was claimed to have. Verified on a couple of rolling roads. Pullled lovely that car!
Rolling roads will never be 100% accurate to rate flywheel power, as the best they can is a semi educated case, derived from wheel/hub figures.And even if you had the engine on an engine dyno it would still be suspect due to how many variances can occur. Such as the type of dyno, how it measures torque, how it calculates HP. What standards you are rating it too and so on. And how the operator has set it up and using it.
Best you can get is a ballpark figure on what it might be. And even then it would be assuming you knew all of these things about the factory rating too. Ie were TVR’s own figure to DIN, SAE Net or something else?
300bhp/ton said:
TV8 said:
Not sure what you mean by ex-factory? My 1st car was a very early 4.0 one and had the 240 bhp and 270lb ft it was claimed to have. Verified on a couple of rolling roads. Pullled lovely that car!
Rolling roads will never be 100% accurate to rate flywheel power, as the best they can is a semi educated case, derived from wheel/hub figures.And even if you had the engine on an engine dyno it would still be suspect due to how many variances can occur. Such as the type of dyno, how it measures torque, how it calculates HP. What standards you are rating it too and so on. And how the operator has set it up and using it.
Best you can get is a ballpark figure on what it might be. And even then it would be assuming you knew all of these things about the factory rating too. Ie were TVR’s own figure to DIN, SAE Net or something else?
I am happy with the similar figures to quoted that I achieved on power runs, just as the people who were not happy on the same rolling roads (Surrey Rolling Road and Austec) when their cars, using the same educated guesses, showed them 10-20% down!
There is only really one way to compare engine power outputs in real time and under the same conditions regardless of what or who’s Dyno its been on.
With experience you can almost watch how the power is being delivered from one engine to the next via drag runs.
I’ve raced other Chim owners with varying degrees of power output as displayed by Dyno graphs etc and the correlation between my engines known power output on Powers Performance dyno and there’s is very obvious.
I have more or equal torque to most 500’s on my 450 engine as I retain the standard 38 mm trumpets but lose out over 4000 revs on HP and it’s easy to see when running alongside another car.
My conclusion is peak figures are only part of the story and how balanced the engine is plays a big part in It’s speed from one point to another.
What I also learned was the engines known to have 350 Hp and more are really fast compared to one with 300
Overall I think the dyno most TVR blokes use for actual tuning are pretty accurate.
Everyone always smirks some dyno are offering higher numbers than others. Well drag racing proved they ain’t. My car is very fast for one with only 300 Bhp.
Based on nothing but my gut instincts I think my late 450 engine with nothing more than a Cam change by TVR when new had about 275 hp based on its grunt and after ecu change and basic rebuild a known 300 BHP. It’s not that much faster top end at all but is much smoother and full of torque lower down, it spins up faster which is where it’s extra acceleration seems to come from rather than because it has lots of extra power.
With experience you can almost watch how the power is being delivered from one engine to the next via drag runs.
I’ve raced other Chim owners with varying degrees of power output as displayed by Dyno graphs etc and the correlation between my engines known power output on Powers Performance dyno and there’s is very obvious.
I have more or equal torque to most 500’s on my 450 engine as I retain the standard 38 mm trumpets but lose out over 4000 revs on HP and it’s easy to see when running alongside another car.
My conclusion is peak figures are only part of the story and how balanced the engine is plays a big part in It’s speed from one point to another.
What I also learned was the engines known to have 350 Hp and more are really fast compared to one with 300
Overall I think the dyno most TVR blokes use for actual tuning are pretty accurate.
Everyone always smirks some dyno are offering higher numbers than others. Well drag racing proved they ain’t. My car is very fast for one with only 300 Bhp.
Based on nothing but my gut instincts I think my late 450 engine with nothing more than a Cam change by TVR when new had about 275 hp based on its grunt and after ecu change and basic rebuild a known 300 BHP. It’s not that much faster top end at all but is much smoother and full of torque lower down, it spins up faster which is where it’s extra acceleration seems to come from rather than because it has lots of extra power.
TV8 said:
How do you know you have 300BHP per ton then
I am happy with the similar figures to quoted that I achieved on power runs, just as the people who were not happy on the same rolling roads (Surrey Rolling Road and Austec) when their cars, using the same educated guesses, showed them 10-20% down!
Are you suggesting Surrey rolling road read low? I found the opposite on more than 1 occasion. For example I had mine tuned by Dale at Bailey performance and got 308bhp. A couple weeks later in similar weather conditions saw 328bhp at SRR. I believe Dales rollers to be quite accurate and suspect SRR have exaggerated drive train losses added.I am happy with the similar figures to quoted that I achieved on power runs, just as the people who were not happy on the same rolling roads (Surrey Rolling Road and Austec) when their cars, using the same educated guesses, showed them 10-20% down!
As Alun says the most accurate way in my opinion to compare our cars is to go to the drag strip and look at terminal speeds. It matters little how much grip or how hard you launch as that only improves your ET, The terminal speed will always be within a couple mph and with all our cars weighing similar then we can calculate bhp. I use an online calculator on a website called torquestats and found it very accurate.
DangerousDerek said:
TV8 said:
How do you know you have 300BHP per ton then
I am happy with the similar figures to quoted that I achieved on power runs, just as the people who were not happy on the same rolling roads (Surrey Rolling Road and Austec) when their cars, using the same educated guesses, showed them 10-20% down!
Are you suggesting Surrey rolling road read low? I found the opposite on more than 1 occasion. For example I had mine tuned by Dale at Bailey performance and got 308bhp. A couple weeks later in similar weather conditions saw 328bhp at SRR. I believe Dales rollers to be quite accurate and suspect SRR have exaggerated drive train losses added.I am happy with the similar figures to quoted that I achieved on power runs, just as the people who were not happy on the same rolling roads (Surrey Rolling Road and Austec) when their cars, using the same educated guesses, showed them 10-20% down!
As Alun says the most accurate way in my opinion to compare our cars is to go to the drag strip and look at terminal speeds. It matters little how much grip or how hard you launch as that only improves your ET, The terminal speed will always be within a couple mph and with all our cars weighing similar then we can calculate bhp. I use an online calculator on a website called torquestats and found it very accurate.
The reason they are neither high nor low, is simply because the "Hp" unit they get is pretty unique to their setup, their environment and how it is being used.
If they changed makes of dyno and did everything else the same, they would likely get different numbers, but they would be still just as accurate when compared to like numbers.
Think of it this way $10USD and $10AUS are both ten dollars. But they are not the same thing.
e.g.
240hp from one rolling road is not the same 240hp from another, nor is it the same as 240hp claimed from a car manufacturer. At best you can use these as guidance, but they are not absolute or directly comparable.
TV8 said:
How do you know you have 300BHP per ton then
I know I don't. It is just a username TV8 said:
I am happy with the similar figures to quoted that I achieved on power runs, just as the people who were not happy on the same rolling roads (Surrey Rolling Road and Austec) when their cars, using the same educated guesses, showed them 10-20% down!
I'm glad you are happy It still doesn't make the figures any more comparable however, dynos and physics just don't work that way.
DangerousDerek said:
Are you suggesting Surrey rolling road read low? I found the opposite on more than 1 occasion. For example I had mine tuned by Dale at Bailey performance and got 308bhp. A couple weeks later in similar weather conditions saw 328bhp at SRR. I believe Dales rollers to be quite accurate and suspect SRR have exaggerated drive train losses added.
.
Not suggesting SRR reads low, but don’t care that much either! I said, I was happy with my readings and they were what TVR said the car should have. Then I explained that some cars were showing as down on power on the same rolling roads..
TV8 said:
300bhp/ton said:
I'm glad you are happy
It still doesn't make the figures any more comparable however, dynos and physics just don't work that way.
Some people! It still doesn't make the figures any more comparable however, dynos and physics just don't work that way.
What part of two separate dynos giving the same answer as the cars stated specification isn’t comparable?
As said, that just isn't how rolling road dynos or physics work. And as demonstrated by the ops post, TVR claimed different figures anyhow.
300bhp/ton said:
Rolling roads will never be 100% accurate to rate flywheel power, as the best they can is a semi educated case, derived from wheel/hub figures.
And even if you had the engine on an engine dyno it would still be suspect due to how many variances can occur. Such as the type of dyno, how it measures torque, how it calculates HP. What standards you are rating it too and so on. And how the operator has set it up and using it.
Best you can get is a ballpark figure on what it might be. And even then it would be assuming you knew all of these things about the factory rating too. Ie were TVR’s own figure to DIN, SAE Net or something else?
But these semi educated guesses as you put it are accurate on serious tuners dyno as if you use the power to weight calculator inputting your cars weight and known power ( via a dyno) etc and have timing slips from a number of 1/4 mile terminal speeds you will find the numbers line up very closely indeed. If your engine did not have the power your dyno numbers suggest it will not make the terminal speeds it should and almost all the faster cars I know of the numbers align when using these calculators. And even if you had the engine on an engine dyno it would still be suspect due to how many variances can occur. Such as the type of dyno, how it measures torque, how it calculates HP. What standards you are rating it too and so on. And how the operator has set it up and using it.
Best you can get is a ballpark figure on what it might be. And even then it would be assuming you knew all of these things about the factory rating too. Ie were TVR’s own figure to DIN, SAE Net or something else?
So clearly the dyno used on these TVR were all fairly accurate.
I think various Rolling road days such as at the Griff growl where cars are quickly strapped down and 3 mins later it’s all done have skewed the truth somewhat.
So forgetting the clock race a known Tvr tuned off another dyno to the one used on yours and watch what happens based on the numbers alone.
It tells you everything you need to know if the two dyno are accurate.
Based on the dyno curves you can predict where one will be faster or indeed slower and the real race just replicates the dyno results really.
I’m very confident both cars I’m talking about had exactly the power the dyno had suggested using different machines.
Edited by Classic Chim on Saturday 13th February 09:37
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