Rolling road result from Growl

[dnb]

I have no scanner, so here is a table of my RR results from Saturday.
Torque was calculated using torque = power*5252/RPM.

I will edit a graph in here when I am home, but it will simply be an excel plot of the numbers as I don't have a scanner.

RPM	Power/bhp	Torque/ftlbs
2000.	95	249
3000.	180	315
3700.	215	305
4000.	230	302
5000.	256	269

So, the power is low, but the low down torque is a little silly as noticed by Pasco. I am blaming the standard lousy TVR induction for this, so I have a plan to correct it (more to say later, but remember some of the shiny bits on the V8 Enhancements stand...) but is there anything else more sinister I should think about?

Edited a few times to make the table work!

Edited by dnb on Tuesday 21st August 17:17

[dnb]

Here's the graph:

[Pasco]

Sticking my nose in on the Rolling road users on Sat and Sun out of all of them your results surprised me the most Blady

So to help me get my head round the graph...............

what plenum and trumpets etc do you have on your car

You have a H404 cam yes ?

You are using a Vems ecu ? with coil packs and no AFM or dizzy


Pasco

[trackcar]

thats way down Dave .. i see 320hp from the H404 in a 5 litre with only subtle other mods .. I'm assuming its a flywheel figure youve posted

[Pasco]

trackcar said:

thats way down Dave .. i see 320hp from the H404 in a 5 litre with only subtle other mods .. I'm assuming its a flywheel figure youve posted

Hi Joo hence my surprise and Flywheel numbers

I expected at least 320bhp but something is wrong or missing from the equation

Pasco

[Pasco]

Unless you are starving it of air Dave i presume you are not using the standard 500 plenum ?

[Pupp]

TBH, having seen a load of cars run over both days, I did wonder whether the dyno was reporting on the lowish side... A nice T350 (I would have thought) would easily better 290ish, no? As it was drizzly much of the time, I wonder whether there was tyre slip occurring? Just thinking aloud and prolly well off track.

[Pasco]

Pupp said:

TBH, having seen a load of cars run over both days, I did wonder whether the dyno was reporting on the lowish side... A nice T350 (I would have thought) would easily better 290ish, no? As it was drizzly much of the time, I wonder whether there was tyre slip occurring? Just thinking aloud and prolly well off track.

Hmm well i recon the dyno was reading around 15 to 20% lower than i expected on average based on my knowledge and on the cars i know Pup imho

Pasco

[clive f]

need dave to confirm, but I`m sure he won`t mind me saying that I`m pretty certain he is running the standard phlenum, trumpets or tube off cuts that tvr used, and induction pipe, obviously no afm as he is running vems, so if he was using 72mm phlenum, with say carbon trumpets, his figures would be higher as like he says he is starved of air.

[Pasco]

Carbon Trumpets

[Vixpy1]

We have the same dyno, however never having put it outside i could'nt comment on the rain affecting slip. What i do know is when we put cars on with wet tyres they dry very very quickly, and slip on these dynos should really not be a problem with dry tyres. Unlike other dynos they should never vary in readings, and should all read the same.

It would help if someone could post their graphs up

Oh, and for reference, my 5 litre golf cart makes 292bhp on our rollers, standard apart from cam and exhaust, i would expect Dave's to be well up on that

Edited by Vixpy1 on Tuesday 21st August 22:17

[dnb]

Bog standard induction, apart from a bit of tube where the AFM should be. Yes, it's definitely starved of air (see my other thread - http://www.pistonheads.co.uk/gassing/topic.asp?h=0... but I don't intend to do anything about it for the next 3 weeks

Edited by dnb on Tuesday 21st August 23:11

[eliot]

Matt's 500 (midnightblue) pulled 299bhp on the Saturday morning, ACT trumpets, megasquirt & std 65mm inlet.


bigger:
http://www.mez.co.uk/ms11.html#nobling

Edited by eliot on Tuesday 21st August 23:27

[dnb]

And no induction pipe at all. Just an open butterfly...

The RR was accurate. I worked out some approx figures from the data logs I took, and all are within 5%.

[dnb]

Just for interest, here's what the car thought it was doing for the run.
It's difficult to see, but the injector pulsewidth (PW) is dropping after 3500 RPM even though the AFR (measured in lambdas) is staying correct. So where is the air going? Clearly it's not into the engine.

[Vixpy1]

What Lambda are you running WOT ?

PS, i've sent you mail view 22b

[eliot]

dnb said:

Just for interest, here's what the car thought it was doing for the run.
It's difficult to see, but the injector pulsewidth (PW) is dropping after 3500 RPM even though the AFR (measured in lambdas) is staying correct. So where is the air going? Clearly it's not into the engine.

Plot your air inlet temp, if the temperature of the air goes up uuring the run the PW goes down. Can you post that part of the datalog (or email to me [e-mail])

Edited by eliot on Wednesday 22 August 07:09

[trackcar]

you would expect the PW to decrease in that way anyway .. your peak torque / peak cylinder efficiency will be about that point, so that's where most fuel is demanded .. from that point on the fuelling requirements are going to get less.

[dnb]

Eliot - I'll sort the IAT out when I get home - no access to car datalogs at work. (I don't think there was that much change with the IAT over the run)

Joo - That's exactly the point. The question is: Why is the peak torque at 3k when it should be up around 5k5? Surely it can't just be air starvation?

[Paul V]

I ran my Tuscan S there, the first time around it only made 289 bhp, they started to take the car off the rollers when I asked what they had revved it too, turned out they let off at 5000 rpm, the second run it made 346.4 bhp by taking it too 6800 rpm

Edited by Paul V on Wednesday 22 August 11:03