Post your dyno curve here

[macdeb]

I'd like to go to the FOS some day, looks a good meet with some interesting cars.

[ChilliWhizz]

TV8 said:

ChilliWhizz said:

Back home at the weekend Peter, and probably for a few weeks.... Going to try and get to FOS too, if only for the Thursday and Friday...

Hi Richard, I am booked in for the FOS on the Thursday. Would love to meet up with you and say hello if you don't mind the company of Mrs B and my lad? PM sent

mail sent

[ChilliWhizz]

macdeb said:

I'd like to go to the FOS some day, looks a good meet with some interesting cars.

Feck me Mac you sound like Cinderella mate Wot abaht this year then

[domV8]

phazed said:

Heads will give more of everything.

I think that those in the know will agree with that.

...

As for programmable mapping, I had over 330 bhp with the 14CUX on my 4.6 with a solid cam admitedly.

Anthony's has also been "Mark Adamsed"

Not sure that's entirely true Peter - certainly not my experience

Putting Dereks special heads on mine moved the torque up the rev range, but did not change the "shape" of the torque graph.

Moving the torque up gave higher BHP, at the expense of the lower end torque - ie. although the torque "shape" was the same, I now had 20lb less torque at 2000rpm for example. We all know this, as it is the usual effect of larger port areas having a detrimental effect on gas speeds at lower RPM.

However, although the torque shape hadn't changed - my peak torque value has fallen (although this was read at 500miles into a new engine, so should have loosened up slightly since then), my guess for this is that the engine does not fill the cylinders as efficiently at the higher RPMs than it did previously at the lower RPMs, so again - lower volumetric efficiency.

So the outcome of changing my heads up (mapping adjusted accordingly) was higher BHP and a longer overall rev range, at the expense of less torque down low and a lower overall peak torque figure.

This has made the car more in line with what I was trying to achieve (revvier with more power at higher rpms) - but I was still surprised at the 15lbft drop in peak torque I saw...

So I think you have to be careful, as saying "more of everything" is a little misleading in my experience - given the drops in low-down torque and peak torque figures I saw, to achieve more revs & BHP.

I know Anthony is very specific about what he wants from his car for his driving style - so think its worth careful consideration about ALL effects he may experience before spending 1000's on heads, installation and remapping...

With respects to you previous 4.6 - always thought that was one of the best 4.6's to date, wonder what further gains you might have seen with ignition mapping etc too...?

All IMO,


Dom

[Sardonicus]

In all fairness Dom a correctly ported pair of heads should cost you nothing low down i.e what you lose on port velocity etc you can claw back with un-shrouded better shaped intake valves (low lift flow gains) improvements should be made right through the rev range IMO but I am no RV8 expert so stand to be corrected

[spitfire4v8]

A better flowing head allows to you run less cam for any given hp too, so I would almost always say go for the best flowing heads you can, and use the least cam you can, to get where you need to be.
Also the hp at 2000rpm is largely irrelevant to a sports car .. if you're flat out at 2000rpm you're in the wrong gear (or the gear lever has fallen off lol)

[domV8]

Sardonicus said:

In all fairness Dom a correctly ported pair of heads should cost you nothing low down i.e what you lose on port velocity etc you can claw back with un-shrouded better shaped intake valves (low lift flow gains) improvements should be made right through the rev range IMO but I am no RV8 expert so stand to be corrected

I suppose this is the crux of the matter Simon - correctly ported to your engine set-up & desired performance characteristics.

Dereks heads were worked over by Pete Burgess with all the usual attention to detail (given his reputation, the final product should be good!), and I run a TVR885 cam, supposedly less wild than the Stealth. (re: Jules post above)

Keeping the same cam unchanged - my experience was seeing peak torque move from 4250rpm to 4900rpm with a drop in peak torque (mapped at 500miles on new engine caveat), and all the other things mentioned in my post above.

What *should* happen, and what *does* happen can sometimes be two different things - as per my experiences as documented...

I just think one has to be careful when suggesting benefits with no drawbacks, as the final outcome may be different to what was proposed (probably based on the engines individual setup/characteristics) - as highlighted by my experiences which do not conform to your statement regarding the mitigation of low-down performance loss...

I was expecting torque moved higher up at the expense of less torque low down, and thats what I got (although less peak torque - eek!). Had I been expecting nothing but improvements everwhere, to find out the performance characteristics were not as I expected after spending a few £1000's would be galling...

spitfire4v8 said:

Also the hp at 2000rpm is largely irrelevant to a sports car .. if you're flat out at 2000rpm you're in the wrong gear (or the gear lever has fallen off lol)

Granted - this was just to highlight the point of the torque curve moving up the rev range

[macdeb]

ChilliWhizz said:

macdeb said:

I'd like to go to the FOS some day, looks a good meet with some interesting cars.

Feck me Mac you sound like Cinderella mate Wot abaht this year then

A very good point mate, just looked and will be there especially as 'Rossi' is rumoured to make an appearance which would mean I've seen him twice this year
of course this is if I'm not working due to government tarrif cut on 1st July
I'll give you a call if we do

[TVRJAS]

Posting my results from the rolling road at BBWF.

1997 standard 400 Chimaera 58,700 miles. Just silicone hose upgrade + sleeved box with all cats still in.

The graphs don't really mean much to me but was told from the guys that did it that from a standard 400 this was very good. Comments would be appreciated from those that know more about these graphs please.

[phazed]

Power and torque are about average for a good 400.

Your fuelling is a bit up and down but as you are running the 14 CUX I can't see how it can be improved.
You don't want it any leaner at full throttle yet it is running a bit rich in the mid range.

[TVRJAS]

A reply coming from someone I respect... thank you Peter.

They wrote on the graph that fuel pressure regulator would help,but that seemed to be the report on a few that I spoke with.

I actually asked a few people if you were at the event but got blank faces,and couldn't spot your car to say hello.

Your comment of "a good 400" is pleasing... Cheers Peter

Jas

[phazed]

If you increase the pressure the whole fuelling band will alter and move up or down.

You could try a rising rate regulator but long term I would save the pennies for an aftermarket ECU, especially if the car is a keeper.

I was there all day, car parked up with bonnet up on Saturday! You couldn't miss it

[ChimpOnGas]

TVRJAS said:

1997 standard 400 Chimaera 58,700 miles. Just silicone hose upgrade + sleeved box with all cats still in. Comments would be appreciated from those that know more about these graphs please.

Ditch the cats, especially the big one in the Y piece, that will definitely be your best back for buck

Do the dyno run again with no cats and you'll probably see a 10hp increase, it would be interesting to see what happens to the AFR trace too.

For reference my 4.0 litre makes 250hp on the nose with a Stealth cam, no cats and Canems fueling & ignition control.

It does this on both petrol & LPG, but the important bit is it does it with absolutely standard 4.0 litre heads.

I predict a set of decent heads would give me the 270hp TVR said my 4.0HC made when new, 270hp from a 4.0 litre should be seen more of as an achievable target after much spending than a figure they ever got close to when new.

I'm pretty happy the 250 ponies without head work figure as it goes, drivability is more important to everyday usability than you might think and a 250hp 1100kg car is still quite brisk.

To that end ditching the cats will also make your TVR a smoother drive, well that was my experience.

Kill the cats..

[TVRJAS]

Thank you David for your comments.

My personal issue of taking the cats out is that I have a full sleeved box and on hearing cars that are fully decatted and sleeved is just to aggressive for my ears. My set up although loud gets many positive comments and more important is I like the sound as it. So this would mean for me I would have to have the box put back to how it was at more expense.

Also the concern of mot time arises,from what I read people seem to swap and change themselves when the time comes but I'm not capable or want this faff each year. I was disappointed that when I had my manifold gaskets replaced I asked them to take the pre-cats out but on collection they told me they left them in because they were in good condition. I didn't ask for a report on what condition they were in,I wanted them out and they decided not to.

I've also just had an expensive month Tax,mot,insurance and 12k service all coming together so really don't want to start throwing more money just yet to gain a bit more hp but may do in the near future.

I need to search and read more about this mot and decat business,many threads about it but at this stage I'm confused that without going "ACT Y piece" how if you leave the original set up and just take the cats out what you do at mot time. (Hope that makes some kind of sense)

[ChimpOnGas]

TVRJAS said:

Thank you David for your comments.

My personal issue of taking the cats out is that I have a full sleeved box and on hearing cars that are fully decatted and sleeved is just to aggressive for my ears. My set up although loud gets many positive comments and more important is I like the sound as it. So this would mean for me I would have to have the box put back to how it was at more expense.

Also the concern of mot time arises,from what I read people seem to swap and change themselves when the time comes but I'm not capable or want this faff each year. I was disappointed that when I had my manifold gaskets replaced I asked them to take the pre-cats out but on collection they told me they left them in because they were in good condition. I didn't ask for a report on what condition they were in,I wanted them out and they decided not to.

I've also just had an expensive month Tax,mot,insurance and 12k service all coming together so really don't want to start throwing more money just yet to gain a bit more hp but may do in the near future.

I need to search and read more about this mot and decat business,many threads about it but at this stage I'm confused that without going "ACT Y piece" how if you leave the original set up and just take the cats out what you do at mot time. (Hope that makes some kind of sense)

I have an ACT Y piece and a standard box, Ive also removed the pre-cats.

The sound is great but never reaches the wrong side of too noisy in my opinion.

Actually it's quite civilised for a TVR when cruising at my typical 80 plus and the MoT has never presented an issue as there's normally a nice Renault Clio or modern Fiesta close by to take one for the TVR team.

All you need is a reasonable tester and you really shouldn't have any issues, just have a man to man chat before you book in and use a local independent test station where you can have a frank discussion to get an idea of his view on the emissions test.

You're not committing the worlds biggest crime going cat free, but you will find an extra 10hp, which means you'll use a bit less throttle for the same given speed and so a little less fuel which means you'll be doing your bit for the Dolphins anyway.

Definitely well worth doing, just like its well worth ditching those stupid shrouded 7s for a 6 rated projected electrode spark plug set.

[TVRJAS]

ChimpOnGas said:

Definitely well worth doing, just like its well worth ditching those stupid shrouded 7s for a 6 rated projected electrode spark plug set.

This is what I meant when saying the graphs mean very little to me.... So you can tell what plugs I've got from those charts I'm gobsmacked

He did actually tell me this,that changing my plugs I would see a benefit but be prepared it can be a bit pricey.

I can't comment further about the de cat approach,as I said I need to do some searching and reading of old posts and I'm sure I'll find the answer. But from what I've briefly read I know you are right that loosing them helps in many areas.

Thanks again David

[QBee]

Jason, I wholeheartedly agree with Dave, but here's an alternative view.

If you are only driving your car on the public road, save your serious lumps of cash for necessary service work and fuel for enjoying your car.

By all means change those plugs at the next service for iridium 6s. I did, and mine runs better on them. They are about £9 each.

But think hard before you spend hundreds or even thousands to gain 10-20 bhp. You quite frankly won't notice the difference on the public road, and will feel disappointed that you spent all that for what?

IMHO big BHP gains are useful. Big torque gains are mega, especially on track. Small gains of either aren't worth it.

[TVRJAS]

Hi Anthony,

I just had a 12k service three weeks ago... As I'm sure you know I don't track my car it's road usage only,I fully understand people that do in wanting to achieve as much as possible,but in my case this doesn't apply.

Of course if someone directed me how to obtain 20-30 extra hp at a the cost of a couple of hundred then I'd happily go that route,thousands nope,I would sell my 400 and buy a 500. What David is saying I fully agree with that taking cats out will improve my result,but because of my sleeved box then this is not as straight forward.

The price you say about the plugs is way less than what I had in mind,I haven't purchased a spark plug since my Motocross days (That's a long time ago). You may laugh but I thought this changing of plugs was going to be £20 X 8. If you all think I would benefit and see some difference at 8X £9 I will happily part with the money.

Thanks Anthony for maybe preventing me from falling into the bottomless pit

Edited by TVRJAS on Sunday 5th July 22:33

[QBee]

These are the ones I have, and that Dave recommends:

plug linky

As you can see, £7 per plug, so £56 in total

[TVRJAS]

Up early there Anthony..

Very kind directing me to that linky.

Many thanks... Jas