500 out of puff

[Jammie Dodger]

Now I know the 4.0/4.3/4.5 are shorter stroke and higher revving, but my 500 is gasping at 5100rpm in top. To be fair I don't rev it beyond 5000 in any lower gear because i don't need to.

Feels plenty strong otherwise and my mechanics David Gerald reckon it feels like a proper 285bhp. Just had the tacho changed (for one that works) and seems accurate by the 27mph/1000 in top formula.

What's going on . Any ideas ?

[carsy]

Whats the mileage. Often a sign that the cam is wearing.

[Ant.]

Check that the inlet pipes are in good condition, they can collapse if not in a good state.

[Jammie Dodger]

28000 miles (late 98 car)
Surely bad pipework would hamper it all the way through the range ?

Should've held on for the right Tamora or T350t - in the month vie owned the chim i've spent £800 sorting it out so far, with nitrons, rose joints, rear discs and 2 tyres to come next week, best part of another £2000. Plus music, which was £1700.

Once I start on cams and plenums and and and then it's going to be a very expensive car !

Edited by Jammie Dodger on Monday 6th June 22:46

[Alexdaredevilz]

Stick it on a dyno, and go from there

Cams aren't hard to change

[macdeb]

If you don't mind me saying, and I mean no offence but I reckon your biggest mistake so far is the £1700 on music

[Jammie Dodger]

macdeb said:

If you don't mind me saying, and I mean no offence but I reckon your biggest mistake so far is the £1700 on music

I didn't want halfords touching it and one thing led to another.....

Still, 27mph per 1000rpm times 5000rpm equals a lot of wind noise to drown out

[Jammie Dodger]

Alexdaredevilz said:

Stick it on a dyno, and go from there

Cams aren't hard to change

Weird thing is it feels strong otherwise. Just at 5100 in top you can feel it stuttering/gasping. I thought even a 500 was good for 5750...

[Alexdaredevilz]

Jammie Dodger said:

Weird thing is it feels strong otherwise. Just at 5100 in top you can feel it stuttering/gasping. I thought even a 500 was good for 5750...

My 4.6 pulled 6700 the other day

If i were you id stick it on a dyno and see whats going on, you gauge might be out

[dumbfunk]

My Griff500 will clatter into the limiter if you're not careful so there is definitely something amiss. Either the spark is breaking down or there's an air/fuelling problem.

£50's worth of rolling road will save you hundreds in guesswork.

[spend]

Spin it up in low gears or neutral to see where the rev limiter is set, just make sure it's warmed up nicely before bouncing off the rev limiter.

[Jammie Dodger]

thanks Spend, did occur to me to try that. Problem with 5100 in top is by that time it equates to 135mph, by which speed all sorts of other factors are coming in to play. Maybe aerodynamics starving the engine airflow at that speed ?

[big geoff]

use it more it will get better

[V8 GRF]

My money is on a worn cam. You can do a quick check by taking a rocker cover off and seeing if all the valves are opening and shutting as they should, that was how we diagnosed mine.

[Jammie Dodger]

Doug Elwood did suggest we could look at a new cam, as 285ish bhp isn't that electrifying. Trouble is, if i started thinking too hard about engine mods, i'd end up upselling myself into SC/Taraka + territory.

I bought a RV8 because I wanted it to be cheap to keep (relatively) against a Tam/T350

lol...

I'm going to have to find somewhere out of the way to scream it up to the limiter

[V8 GRF]

Jammie Dodger said:

Doug Elwood did suggest we could look at a new cam, as 285ish bhp isn't that electrifying.

It's about standard for a 500 though.

My car has a dyno readout of 299 that was recorded after after some intake mods but had fallen to 242 The cam transformed the car, just nicer in so many ways, I hadn't realised what a pig it had become.

[Jammie Dodger]

V8 GRF said:

It's about standard for a 500 though.

exactly, so i assumed that all was well with the powerplant (inc. cam)

I'm obviously learning all the time, not skilled in getting my hands dirty. That's why i assumed it to be an issue other than the cam, as the engine feels strong enough for standard - Just gets short of breath after 5k...

[LordGrover]

Jammie Dodger said:

28000 miles (late 98 car)
Surely bad pipework would hamper it all the way through the range ?

As anyone hear will testify, I'm clueless when it comes to engines/mechanicals, but I suspect that's not quite right. Lower revs calls for less air, high revs demands more, surely? If the pipework is restricted in any way it'll be more noticeable/measurable at high revs, I'd've thought.
If you still have the original corrugated 'hoover' hose, especially at the 90° elbow, I'd suspect something could be improved/fixed there.

[Jammie Dodger]

yes, that does make sense. It's back into David Gerald on monday for the nitrons etc., so will check the lungs system. Against my better judgement, i can feel some extras coming on...

[900T-R]

Jammie Dodger said:

Doug Elwood did suggest we could look at a new cam, as 285ish bhp isn't that electrifying.

No offense meant, but even driving cars back to back I'd be really surprised if anyone's butt dyno was so finely calibrated to say it was 285 bhp give or take. In reality, I bet it can be everything from 220-300.

Stick it on a rolling road and see what happens.

The stuttering/hesitating above 5,100 isn't normal - in 4th or lower you should be easily able to redline it, although there's little point to go much past 5k in a std 500.