Can you interpret this dyno chart!!!

[chris1972]

I know there's a lot of experience here, but can anybody interpret this graph and perhaps identify any immediate bottlenecks? I understand air intake is one of them and it's on my more immediate list of things to do, followed by an ECU upgrade. I suspect it hasn't had a proper map either.

Thanks in advance!

[Kokkolanpoika]

Is it chimiera 500 or? Your flywheel power is quite high vs wheel power. Loss power is over 50hp. If it is automatic, that should be ok. But not for T5 or LT77 manual.. 13-15% more with wheels should be quite optimal results for flywheel, not like +20%. So i will say you have got approx 250hp max..
Engine need more air and fuel, thats all.. I dont see any thinkg bigger resistor with this graph.. Usually it will drop like wall if there is some big resistor.. My 5.2litre drop 5000-5500rpm range near 80hp when fuel pressure drop approx 1kg. now with new pump, throttle bodies it will give over 120hp more than old system..

Have you got AFR results?
Or have you measure engine vacuum at dyno?

[LuckyLucky]

Looks like a typical graph for a good 500.

A lot of dynos add 25% to the on te wheels figure, I don't see why the can't all standardise their callculations!

[JPW231]

I think that looks a good graph too. Looks like you've gt a healthy 500 Chris

[fausTVR]

Looks like fairly healthy numbers for an untuned 500 to me. Transmission losses would be a fairly consistent BHP figure (50ish?), rather than a percentage. Afterall, losses on a 400 would be pretty much identical to those on a 500 with identical transmission. So talk of loss percenatges when comparing cars is misleading. I would have thought 15 or so extra bhp were available just through some very basic servicing, such as ign timing advance (combined with high RON), clean air/fuel filters, plugs, leads, etc.
An air/fuel ratio graph would have been useful on that chart.

[Chilliman]

Hi Chris, I've put one of my old dyno sheets below in case it might be of interest You'll see you have much more torque lower down than I did.. when the engine was stripped it turned out there were no trumpets, they'd been removed by a previous owner and the base had been blended. As far as I'm aware these were the only mods, the rest of the engine (including induction hoses) were as it left the factory.

Not wanting to teach you to suck eggs but before spending dosh on tuning stuff (smooth bore inlet etc) I'd do a health check on the engine, particularly condition of the cam and a compression test. As the guys have said, the AFR will give a good indication of how efficiently it's performing. Also, use the same RR next time round, and keep your eye on the WHP figures.

Chilli

[chris1972]

Thanks for this and thanks for your dyno chart Chilli, yours does seem a little more comprehensive than mine!

I'm not too worried about cam wear at this stage. It had a top end rebuild at Austec in March 2009 and was fitted with a Piper 218 at the time, which are meant to be good for drivability, but not the best for horses. I guess if it had the stealth cam, the dyne may have shown a few more HP. It has done about 6k miles since the rebuild. I have noticed that Austec fitted it with a recon ECU in 2011, so I'll check the chip as per the other threads. I'm building quite a list of jobs!

I also intend to paint the plenum at some point (one of those more therapeutic jobs), so will check the trumpets and make sure they're all still there!!! From what I can gather, the car is pretty much standard and has never seen a remap, so there seems to be plenty of scope for adding horses.

[Vixpy1]

looks fine for a standard 500

[Dodsy]

I thought those figures looked low for a 500 , but I only have my 450 to compare them to. The only modifications I have are removal of the pre cats and an ACT silicon induction pipe. Last time it was tested I had 214.7BHP at the wheels, I would have thought a 500 would make a lot more ?

[Vixpy1]

Dodsy said:

I thought those figures looked low for a 500 , but I only have my 450 to compare them to. The only modifications I have are removal of the pre cats and an ACT silicon induction pipe. Last time it was tested I had 214.7BHP at the wheels, I would have thought a 500 would make a lot more ?

standard 500's usually barely make much more than a good 450.

[LuckyLucky]

This is an indication on what can be achieved.

Here's a graph for my old 5.0 which was a great motor.

Standard block with the same add ons as my current 4.6 but with a single plenum.

I used Surrey RR which is gives very similar figures to Austec who I have also used.

The before graph, (lower) was with a partially blocked main cat.

Edited by LuckyLucky on Sunday 6th January 14:29

[chris1972]

LuckyLucky said:

Edited by LuckyLucky on Sunday 6th January 14:29

That's impressive!

I gather a full decat, better induction, ECU, such as the Canems and a good map would help achieve these figures. Somthing to plan for in the future!

[Chilliman]

LuckyLucky said:

This is an indication on what can be achieved.

Here's a graph for my old 5.0 which was a great motor.

Standard block with the same add ons as my current 4.6 but with a single plenum.

I used Surrey RR which is gives very similar figures to Austec who I have also used.

The before graph, (lower) was with a partially blocked main cat.

Edited by LuckyLucky on Sunday 6th January 14:29

Hi Peter,

I find this 'main cat' thing very interesting


It seems there are different schools of thought on the restrictions the main cat gives... It's always been a bit of a mystery to me, but some think that the main cat won't block up enough to affect engine power, and yet another school of thought suggests removing it will open up more horses ???? How would you know if the main cat was restricting flow, or to put it another way, the back pressure was too high, which would negate the advantages of the more efficient induction mods. To put it another way, what's the point of increasing the gas flow into and through the engine if the main cat just slows it all up.... I'm led to believe it doesn't, but how can you tell/measure this? Seems to me the big dustbin main cat is the big unknown in the tuning stakes....

I like things that can be quantified, but the 'main cat' issue remains a mystery to me

Chilli

[Kitchski]

That's a hell of a transmission loss there! 25-28hp (in my experience) is the norm when the oils are up to temperature.

[LuckyLucky]

The mystery is simple I believe.

The lower output curves are with the dustbin cat, (I also used another Y piece before but that was even more restrictive!) and the higher output curves are a week later using a dustbin Y piece with the cat removed, which is the one I am using now.

It is cleanish to me that a cat must restrict up to a point, even a small amount but the cats in our old cars may well be partially blocked due to age/mileage/old technology.

If yours is still in Richard, I suggest removing it.

If you want another Y piece to butcher, I have a spare you can have.

[ChimpofDarkness]

Chilliman said:

Seems to me the big dustbin main cat is the big unknown in the tuning stakes....

Not I my car it wasn't

Chilliman said:

I like things that can be quantified, but the 'main cat' issue remains a mystery to me

Chilli

Sadly I can't quantify as I never did a before & after dyno, but immediately after ditching my main cat & fitting the ACT flowed Y Piece my car came alive.

Revved better, idled smoother and felt like a good 10hp or more on the bum dyno.

Coincidence?

I don't think so

Put the big dustbin in the dustbin

[GasMunkey]

I done a back to back dyno with cat and with out, and my cat was NOT blocked

27hp if I remember right, I have a decat piece if you want to try it Chili

Edited by GasMunkey on Sunday 6th January 17:50

[Chilliman]

LuckyLucky said:

The mystery is simple I believe.

The lower output curves are with the dustbin cat, (I also used another Y piece before but that was even more restrictive!) and the higher output curves are a week later using a dustbin Y piece with the cat removed, which is the one I am using now.

It is cleanish to me that a cat must restrict up to a point, even a small amount but the cats in our old cars may well be partially blocked due to age/mileage/old technology.

If yours is still in Richard, I suggest removing it.

If you want another Y piece to butcher, I have a spare you can have.

Thanks Peter, offer much appreciated.... Not sure about the emissions though, or the re-installation of the main cat each MOT time, or the insurance/legal questions that arise.... Correct me if i'm wrong but if you're found to have a car with no cat that had one when new then you've broken the law??? I'm not a squeaky clean law abiding citizen (have been known to do 63 in a 60 zone) but are the risks with decatting worth the risk??? I dunno, I'm a bit of a dunce on this subject....

[LuckyLucky]

I'm no expert on the legality of having a cat but if big brother says that is the case then there's no hope for us.

[ChimpofDarkness]

Chilliman said:

Thanks Peter, offer much appreciated.... Not sure about the emissions though, or the re-installation of the main cat each MOT time, or the insurance/legal questions that arise.... Correct me if i'm wrong but if you're found to have a car with no cat that had one when new then you've broken the law??? I'm not a squeaky clean law abiding citizen (have been known to do 63 in a 60 zone) but are the risks with decatting worth the risk??? I dunno, I'm a bit of a dunce on this subject....

Plod wont be interested Chilli

I told my insurance company and they were even less interested but did send me the usual "That's Fine - no change to policy" email.

Where you will have an issue is at MOT time, with no main cat the car will fail the emissions test for sure.

Saying that at my last MOT my Chim gave the exact same emission readings as a Renault Clio

Funny that

I repeat:

"Put the big dustbin in the dustbin"