The V8 Owners Forum -

thev8kid wrote:is there not one on the 28th Sept?

just been corrected by Stu,
its the 20th Sept

Runs seen here - sounded amazing in person and would not meet the sound check at any UK track at full power!

Run 1


Run 2


Also time to get some tyres that grip - first run smoked the right rear!
Perry
thanks for the comments - where have you seen the car mentioned? It certainly gets photographed a lot from mobile phones etc when driving around.

Ian


IAn

HI All

Thanks for a great day out on my holiday down in oxford.

great to see all the differant cars with the common theme, big V8`s

My ears are still hurting perry from your run..lol
can`t film and hold my fingers in my ears,will bring ear plugs next time..

i will sort an article out on my web site of what runs i have filmed and the picture of the dyno screens from the runs.

Andy

I've filled in the form - could Perry please post or PM the e mail address he wants them returned to

Thanks
Ian

cheers andy,
next time maybe the mini can join us

Sorry, for the delay in posting these up, there is also the data from when the engine was first used and there are some differences to be explained yet....

2008 - August
NORMALLY ASPIRATED TABLE:
Name:David Brooke
Car: MGB GT 3.9
Corrected Engine Power: 193.6 BHP
Engine Power: 192.2 BHP
Wheel Power: 152.7 BHP
Drag Power: 39.5 BHP
Max power @ RPM: 5395 RPM
Torque: 231.3 LBF,FT
Max torque @ RPM: 2840 RPM
Max attained RPM: 5655

1998 - March - Original setup
NORMALLY ASPIRATED TABLE:
Name:David Brooke
Car: MGB GT 3.9
Corrected Engine Power: 207.7 BHP
Engine Power: 203.9 BHP
Wheel Power: 161.8 BHP
Drag Power: 42.1 BHP
Max power @ RPM: 4870 RPM
Torque: 253.2 LBF,FT
Max torque @ RPM: 3537 RPM
Max attained RPM: 6009

As you can see with 10 years wear and tear on the lump the power and torque appear to be down, my problem understanding were the loss might be is that the torque at 2840 rpm in 1998 was 237 lbf ? Cylinder pressures are still the same - as far as I can tell with my tester ! Is the change what is expected from a worn cam? I'll post the power curves later but the different rolling roads could be as significant as anything else.

Like the RWYB idea since the race season is over then and I could compare road and race tyres, good practice for racing starts and most of us with 3.9 where close on non gas power - we could slow Eliott by making him tow the Sherpa....

Dave

Glad you all had such a good time. Feeling very lonely here. Had loads of promises from the shipping company but no paperwork. I'm beginning to think they've lost my engine and I can't talk to anyone 'til tomorrow

Hello chaps

My email is

perrystephenson7@hotmail.com

Got the scanner sorted at last,
First run,


second run

ok im confused with the print out, torque 195.0 lbf,ft and 135 mph at max rpm 0f 5895,looking at some on here there torque is alot higher but lower speed, and what is drag power, rich and the meet up in october for racing sounds good,

Rich

I was also baffled at this and asked on Saturday

What they do is run the car up and then put un neutral and let it slow by itself

So on the "Slowdown" it calculates the drag power - or ttransmission losses rsistance etc.

So by adding together the power that was transmitted to the rollers on the "on power" section to the "drag power" gives the engine power.

Now that made sense to me as a gearbox diff etc will always rob some power.

They also did an exhaust analyst test on mine during the runs as SVA said I was lean and got results from 1.19 at 1700 rpm to 0.828 at 5800 rpm
These numbers do not seem to make sense to me as I expected numbers like 13.5 - 16 - anyone confirm how to convert them?

Cheers
Ian

As I understand values can be expressed in lambda or stoichiometric ratio. A value of 1 in Lambda is = to 14.7 stoichiometric ratio

Your values are expressed as in Lambda so to convert is would be 1.19 * 14.7 = 15.89 (Very Rich) and .828 * 14.7 = 12.17 (a bit too lean)

Am sure someone will correct me if this is incorrect.

r2d2hp

Conversion of figures is correct but you have switched rich for lean and vice versa.

So ian it would appear you a running a liitle lean unless 1.19 was a figure for cruise on a light throttle which is not bad if it runs ok and will give reasonable MPG. Most RV8's wont run well that lean.

Kevin.

Thats interesting R2. I didnt know about that lamba to afr conversion.

So the engine is Lean at low revs and richens as it revs?

So is there a way to raise the level at the idle end of the spectrum without going sloppy rich at top end?

This would also raise a qestion as to how these figures are on the road as presumably these are all at WOT.

I suppose it could also explain my "cutting out on overrun" problem as the lean fuelling would help cause the engine to die

Oh for a carb where you can set the idle jet, then correct the first choke and then do the same for the second! Electronics are difficult!


Ian