250 bhp and 280 torque!!!

[Ubernoober]

Just taken my Chimaera 400 to a rolling road to see what power output I'm getting. Me and the son have had a bet - he reckoned around 220 - 225 BHP and around 250 torques, I thought probably a tad less.

Well, he has won - must say I'm very surprised, not to say highly delighted!!

250 bhp and 280 lbf - and here was me thinking it was down on power!

When I said "the book says 240, I was expecting 215 - is the number right?" the reply was that when they compare their figures with other companies using the same dyno, they are within 2 or 3 bhp and, perhaps more interestingly, they have had Griffs that put out high 200's but never get even close to the book 340 (even a breathed on one 'only' got 320bhp) and that perhaps suggests the number is accurate. Power at the wheels was a tad over 200bhp

A couple of points were mentioned by the guys doing the run - the fuelling was different from what they have seen of other TVRs suggesting a custom mapping or chip? The records I have don't show anything like that being bought or fitted and my back won't allow me to go look!

Also, the rapid drop in power at 5500 rpm - also maybe to do with mapping - or maybe cam?

Now, do I leave well alone or look to add some extra horses???

Oh yes, many thanks to the guys at JKM in Portsmouth - very professional and a nice cup of tea as well!

Fuelling graph:


BHP and Torque

[Dave81]

You haven't mentioned any known mods done to the car (history, receipts etc)???

Tbh if i had 250 out of my 400 i'd rip your hand off.........and not touch it for fear of going backwards!!!
Out of interest whats your fuel economy like (miles to a tank)???

You must be happy to know your getting the performance of some of the bigger engined guys (don't say it to loud)!!

[Ubernoober]

I've just gone through the receipts and history and there's nothing to suggest an upgrade of any description, just regular and good servicing - and a lot of driving!

Miles per gallon wise, I get around 23-24mpg

[Dave81]

Not had mine on the rollers......but my standard (lots of history and no changes) keeps up with my bro's Griff (275 horses). So i believe my car is also punching above its weight also.

Just keep driving the thing!!! Its gained 10 horses so far.....is it to much to wish that the engine gives you more power the more you drive it!!

[rev-erend]

That looks very good..

[thegman]

thats pretty amazing. i hope its accurate. has the RR even run a 400 chim before? what was typical for the RR?

Most 400's struggle to get a lot above 200 at the fly so if you see some eyebrow raising you'll understand why

[dumbfunk]

Amazing numbers! Most standard 500s are in a similar ballpark to this. Even if the road isn't spot on the shape of the curves suggests a very healthy engine.

(If the road is right, your engine *is* tweaked - many demonstrators vehicles for example left the facory with an "optimised" engine set up.)


df

[rev-erend]

Maybe it's got a 4.3 in there..

[900T-R]

Sounds about right, but as it's a 'T' I would expect a 4.6 (aka '450') - and even then it's still a rather good one...

[Ubernoober]

The plate in the engine compartment says it's a 4 litre - is there any way I can eye-ball the engine to see if it is a 4.3 or 4.6?

[Blues]

Those are astonishing figures for a standard 400, well done chap

[rev-erend]

Check on the passenger side of the block - in the middle just below the heads .. facing upwards.. you might need to clean it with a rag.. is the engine number and details.

The top row has engine details and the bottom row the eng no.

My details are ... 46 9.3 (4.6 litre 9.3 to 1 cr)
if the bottom row has NCK in it that would indicate an early 'wild' engine..

Don't publish the engine number here though.. I'm always a bit wary of ringing..

[900T-R]

rev-erend said:

My details are ... 46 9.3 (4.6 litre 9.3 to 1 cr)

My engine builder reported that mine had been - retrospectively - stamped with '13.6' or some stupid high number... Inside it was as normal a 4.3 as they came, though - standard valve sizes, probably a 214 cam (haven't asked, but it certainly didn't exhibit the running characteristics that come with the wileder ones) - massively overported, though and the heads were O-ringed.

[im]

Those looks like Dyno-Jet RR figures.

See my comment here:

http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

12th posting down.

The word 'Dyno' Dynamics is what might be the clue. Also, if your figures are exaggerated by about 20-25 at the wheels, this would then be almost slap bang in the middle of where they would be expected to be on (say) Surrey Rolling Road/Austecs Rollers - 175-180 bhp at the rear wheels.

I'm not having a dig at the figures which I have no doubt are correct for that type of RR but I don't think your comparing like-for-like when other people see this print-out. Obviously everyone coming onto this thread then thinks that their car is perhaps quite a bit down on power and get dis-heartened.

I think TVR Powers RR is also a Dyno-jet so they are quite common just a different type giving a different result - or so I'm reliably informed by the (said) 2 establishments.

For instance, when my Chim was standard I got 174 bhp (at the wheels) at SRR but could have expected, I'm told, about 195 on a Dyno Jet RR.

I don't know enough about this subject to get in too deeply so hopefully Vixpy or someone else can enlighten us as to how this comes about.



IMHO

Edited by im on Friday 9th May 16:50

[Ubernoober]

im said:

Those looks like Dyno-Jet RR figures.

The equipment was stamped Dyno Dynamics - you can see it on their website (web address is on the graphs) - if this is the same as Dyno-Jet, I have no idea.

I have to admit I was sceptical about the figure but the guys insisted they believed them to be accurate and even went on to describe how it is possible to 'fix' the bhp reading. They also said that this Dyno Dynamics rr kit is near the top with regards to accuracy and reliability.

I am certainly not making a comparison - if I wanted to then I would take the car to Surrey or Austec or somewhere with a different dyno and also to another (somewhere in Uxbridge??) with the same dyno (or someone else could go to the same place as I went to) - that would hopefully give a proper representation of the power output. And if the 'true' reading of my Chimaera turned out to be that 'good average' 225bhp - then I'd be quite happy with that!

[StardustV8]

love to know where it gets its extra 80 horses from over mine!

[Ubernoober]

rev-erend said:

Check on the passenger side of the block - in the middle just below the heads .. facing upwards.. you might need to clean it with a rag.. is the engine number and details.

The top row has engine details and the bottom row the eng no.

My details are ... 46 9.3 (4.6 litre 9.3 to 1 cr)
if the bottom row has NCK in it that would indicate an early 'wild' engine..

Don't publish the engine number here though.. I'm always a bit wary of ringing..

Can't see diddlysquat! is it below the exh manifold ? there's the engine number on a plate on the wing but that appears to hold no clue such as yours - certainly with regards to the CR

[Ubernoober]

im said:

For instance, when my Chim was standard I got 174 bhp (at the wheels) at SRR but could have expected, I'm told, about 195 on a Dyno Jet RR.

Surrey Rolling Road website says..... "Our facility is centred around a 4WD Dyno Dynamics Rolling Road, capable of handling up to 1200bhp."

JKM website says...."We operate a Dyno Dynamics 2 wheel drive rolling that is able to accurately graph up to 1200 BHP | 1500 Ft/Lb Torque."


Suggests my figures were obtained from the same make of RR as used at SRR

[Chimjunkie]

Very interesting. There is something about the curve that just doesn't look right Peak bh p at 5000 rpm? Very low? Would have expected a std 400 to have peak bhp at 5500-5750 ish. Maybe the cam is different. But a mid range cam will never give great peak bhp That output would intrigue me to take it somewhere else and confirm! But if you can keep up with the griff from say 60-100 mph, then the output is probably true!

[Jasandjules]

My old 4.0 peaked about 5000rpm I reckon, I used to change up at about 5250 or so........