a 4.2L showing 330 bhp on dyno?

[ZCoupe]

A friend told me that his 4.2L turned out to have 330 bhp of the dyno.

I was (am) very surprised because I thought the 4.2L should be close to the official 360 bhp. This figure came out after re-mapping, changing fuel filter, spark plugs and so on.

Can I be that this is mainly due to not using the car often enough?
Or is it more likely that the re-mapping has not been done proper? or...?

I am kind of scared because i am not using my own Cerb that often...

[OutlawFlat4]

My 4.2 was Dyno'd at 360.4BHP, but many others have seen higher figures.

I started a thread on 4.2 BHP's a little while back..... http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[ZCoupe]

So that would actually mean that the re-map has been done very poor or what do you think?

[Tanguero]

ZCoupe said:

So that would actually mean that the re-map has been done very poor or what do you think?

It's far more likely that there is a problem withe the engine. Any remap is only going to be as good as the underlying condition of the engine will allow.

[Byker28i]

360 would be a mapped car. Mine was always around 343 before mapping although I did once have a 315 as the dunno operator only ran the car to 6k revs. Factory specs were 350 but I've never seen an up modified one get there. They are usually around 320 to 340 (or worse) depending on any issues etc.

So, 330 is about in the right ball park, a slight drop could be in the settings used for atmospherics.
What's the curve look like?

[ukkid35]

Very likely to be valve/shim clearances, and/or blocked cats.

[K4TRV]

What Dyno was used? Was it wheel BHP? Probably, as that will equate to 350/360 flywheel.

How does it drive? Not always down to absolute figures? Was it mapped by someone who has a clue about TVRs (should have gone to Joolz to ask/re-map - AJP V8 guru?)

T

[Byker28i]

this was one from a local dyno:



Where my car always showed 341-343. It depends on the dyno operator

[ZCoupe]

Very interesting to hear.

I will have to ask him for some more details for what really has been done.
As far as i remember his engine was running very well.
But it very well might the case that they did not do a remap but only some adjustment of the throttle pot and so on...
I dont really now the ins and outs and i did not see the curve, but i will ask. Really curious now. And i hope mine will not have such a loss as well.

I know, it would be very good to bring the car to Joolz. But it is easier to say than to do when you are living outside UK...

[ZCoupe]

K4TRV said:

What Dyno was used? Was it wheel BHP? Probably, as that will equate to 350/360 flywheel.

How does it drive? Not always down to absolute figures? Was it mapped by someone who has a clue about TVRs (should have gone to Joolz to ask/re-map - AJP V8 guru?)

T

Now I remember him telling that it was 330 bhp at the wheels.
I don't know much more than that, i will ask for the cuvre.
Engine was (is), as far as i know, always running fine.
I remember him saying the he drove like 4,000 miles since 2008. And that is actually just like mine... way too low.
That is why i am starting to worry about my Cerb

[FarmyardPants]

330 at the wheels is healthy for a 4.2.

[purpleliability]

330 at the wheels is more than healthy!

Mine made 316 at the wheels, 390 at the fly! That was on Joolz dyno

[ZCoupe]

Hmmm... very strange numbers.

I think the torque is very high and the bhp, in relations to the high torque, is very low.
Guess that it all depends on the equipment you use.
But he said car is running wonderful, no oil usage only rubber usage.

[ukkid35]

Suspect that the Torque figure is in NM, making it 302 ftlb.

Edited by ukkid35 on Tuesday 2nd September 14:56

[Steve_T]

Graph doesn't cross at 5252 so agree the scaling must be out.

[ZCoupe]

ukkid35 said:

Suspect that the Torque figure is in NM, making it 302 ftlb.

Edited by ukkid35 on Tuesday 2nd September 14:56

Yes, you must be right.
So all in all not really good numbers

[Mr Cerbera]

ZCoupe said:

I am kind of scared because i am not using my own Cerb that often...

I know, it would be very good to bring the car to Joolz. But it is easier to say than to do when you are living outside UK...

Hi Frank,

You have given yourself the answer to your own problem.

I went to Jools from Lux and it was the best time and money that I ever invested in the car.

Job jobbed !

[Allandwf]

My old 4.2 looked similar to that,had blocked cat.

[Dutch_Cerbera]

Allandwf said:

My old 4.2 looked similar to that,had blocked cat.

Well, I guess that in case a cat would be blocked, the car would be running rough or how was that for you?
And with the MOT the would actually noticed or? But yes, MOT is only once per year so could have happened after or the MOT station was very TVR friendly

[Allandwf]

Drove fine, idled fine,MOT garage was "friendly", so did not show on day to day driving.