Who stole the horses?

[Naybr]

The initial message was deleted from this topic on 09 March 2013 at 06:17

[domV8]

1. Double-check cam wear - some go super quick, long before you'ld think.
2. Check dizzy timing
3. Blocked injectors
4. Blocked cat
5. Dirty air filter
6. Coil

...would be the first things I'd check...


HTH,

Dom

[scotty_d]

Was the same dyno used for both tests?

[jas xjr]

rolling roads do vary as do the operators .some are very iffy imho . back when i was into golf gti's there was one company who seemed to always achieve the best figures for your car

[Naybr]

No it was a different dyno - and some years apart. I do believe yesterday's figures though. The dyno is used for race car set up and is as good as they get. Can't say where it was unfortunately...

Air filter and coil (Bosch) are both new.

By 'dizzy timing' do you mean basic ignition timing or something more sophisticated?

How would I check for a blocked cat?

[lestershaw]

check air leaks around the plenum and afm hose etc, i think you spray easy start around a bit near the plenum, if the revs rise you may have an air leak. i think thats correct?
Lester

[scotty_d]

I don't know of many Chim's that make the TVR quoted BHP numbers from out the box in standard trim, There are a few but not many. Mine made 225bhp with a few mods and i thought that was not bad next to others i have seen on the rollers.

[Alex]

How does the torque curve look? Is it flat, or does it tail off from an early peak?

A worn cam is the most likely cause.

[Naybr]

The torque curve is pretty smooth and tails off after about 5400 RPM

[domV8]

Yes,

check the distributor timing.

Also, the injectors could be blocked, resulting in a poor spray pattern.

Occasionally cats break-up, which blocks the gas flow. But even just a "gummed-up" cat will have an negative effect on power...

However, as said - were the earlier RR figures accurate..?

Dom

[taylormj4]

As well as what DomV8 suggested that might affect engine output, also think of drive train issues that might be sapping power/torque, worn bearings, brakes that are binding slightly, gearbox/clutch, propshaft UJs etc.
Not sure how much each of these could affect things.

[Naybr]

Thanks Guys.

Appreciate the point about differing RRs. I guess my main consideration is how different the current numbers are to the the spec. of the engine. However, to take one of the points above, how good was MY car when it came out of the factory?

The dyno uses an 'overrrun' test to measure the drag of an unloaded drive train and hence can calculate the flywheel BHP. A byproduct of this is that it will show up any slack in diff, UJs etc. I had none, and it's good to know this regardless!

I'll check the timing myself and look into getting injectors cleaned, but can someone advise about checking the cats. Is it 'just' a case of taking them off and looking?

[blitzracing]

Normally if you hold the catalyst up to the light, you should be able to see light through the fine matrix. and when they fail the matrix breaks up or melts which is quite obvious. No so easy to see on a TVR down tube however.

[spend]

In 8 years it may well have had a completely different cam fitted...