David_Wallis

As seen on my own car, it also slugs spool up which can confuse you!

David

swisstonihasher

This topic just goes on and on...

Alan, yes my car has the SC450 turbo same as the gaffers.

Whatever anyone now says I'm not happy with my 935 max EGT temps and constantly over 900, I will be doing something about it when I can. These readings are just after the collector and not from a long blast in top gear, ie if I pushed it more for really fast run I'm sure the readings would go higher!

Kev, thanks for the offer of looking at my car to resolve these issues...will advise.

Re the AFR's, the readings were from the roller time with Pat...I admit to being no expert on them (reading above replies does seem to indicate a technical subject) but no one else has said they run upto 12.4:1?

P20SPD

iTrader: (1)

IIRC My own car is somewhere around 12:1.

As for EGT's, i did 8000 plus miles, hard ones at that, on my built EJ257 with standard Uk heads, regularly seeing 900+ two inches before the turbo. Several times, after long sustained top gear runs, the peaks were over 1000. Yet i never had a problem with valves.

Proteus

Deleted by me - due to me misreading someone else's post !

The Gaffer

Hi,
if you know the BHP and you know the rpm then its easy to work out the torque

TORQUE = BHP x 5252 divided by RPM

therefore

BHP = TORQUE x RPM divided by 5252

Try it .........it works

cheers
Kev.

john banks

I thought the supposed issue with some torque figures is "knowing" the RPM though if it is just set from the car's tacho or diagnostic output and then assumed to be in a fixed ratio to roller speed? Doesn't bother me personally, area under the power curve is what matters as long as the gearing is sensible.

pat

Just some background info for those that don't understand the relevance of RPM pickups....

Firstly, not all dynos have RPM pickups. Some DynoDynamics installations do, some do not. Some other makes don't offer that option at all. Some come with it by default.

The purpose of the RPM pickup is to reduce the errors you get trying to work out engine speed from roller speed. Typically you'de take a car half way up its rev range, then load it up and see what engine speed you have, and what roller speed. You then tell the dyno that is the gear ratio so it can work out engine speed at any other roller speed. So far so good.

Tyres distort when they transmit power. This means that the ratio of roller speed to engine speed is not a constant, but it varies continuously. You have to accept this on some other makes of dyno. DynoDynamics give you the option of purchasing an RPM pickup that can read engine speed directly, either from fuel injectors, spark plug leads, ECU tacho output or any other signal that tracks engine speed (other makes may offer this option too). We have this option and we do use it, but not on every car.... remember, other installations may not even have the option and so their dyno operators have no choice in the matter.

One of the common faults is to measure the gear ratio with the car cruising rather than under load. This will result in the recorded engine speed being lower than it actually was. If you use Kev's formula above, try working out 300BHP at 4000 RPM and again at 4400RPM. Bit of a difference in torque! When we run cars we check the gear ratio under load to get it as close as possible to correct in the first instance, then additionally we compare the max RPM the dyno recorded against the peak RPM in the ECU datalog. If they don't match then we adjust the ratio. Not many other dyno installations are this meticulous in ensuring things are, within reason, as accurate as possible.

I am happy to accept this is not as accurate as running the RPM pickup. Our method results in a gear ratio that is, on average, correct for the car, but as stated previously, the ratio actually varies continuously with load and speed. This can account for a small percentage error in peak torque. The "problem" is that although we have the RPM pickup option, it is difficult to get an acceptable signal from a Subaru engine. We will use it where we feel that the gear method is unacceptably inaccurate. We are not alone in using gear detection as the primary method; other DynoDynamics installations like Town End, DS Automotives (was G-Force), Surrey Rolling Road, and other manufacturer's installations like Power Eningeering, Engine Advantages, Well Lane etc all rely on this method, it's a fairly well established and accepted method. We just have the option of going one step more accurate (that's not to say that other installations don't have or exercise that option, just that they don't as a general rule of thumb).

Hope this helps.

Cheers,

Pat.

AlanG

Hi Kev
My results last year were brought into question as the torque on mine was deemed artificially high.
Pat looked into it and concluded that the "error" could be down to the anomolies he has outlined in the above post.

Here's my graph and yours..






You can see the similarities.. for example continuing to run the engine up the rpm scale even though power has peaked early etc.
Because both these engines are able to produce a lot of torque anyway, then it was deemed the only way to obtain reasonably accurate results in these instances would be to use an ignition pickup.

Re: TEG (Town End) using gear detection as the primary method. I was told that the ignition pickup was faulty when i went to get my car mapped, but is normally in use. Whether they use it "per se" on any car that is in or whether they only use it for those whose cars can give "additional issues" when being run up on the rollers i.e. "high torque" engines, i can't say, that's for Steve Simpson to comment, though i can say that on a subsequent visit, the ignition pick up was used along with a check against his method of using gear detection and both results were very similar.

jim litten

TEG used the rpm/injector pick up for all the cars that ran on the RR day back in April, so I assume Steve uses it all the time now.

harvey

iTrader: (48)

Pat : I thought you might have respected Tony's request. It is his thread.

You do not want to start another thread. Fine, I will when time permits.

Please do not try to quote me out of context.

From Pat.
Quote:
Originally Posted by Harvey
Quite simply, AFRs on a road going Subaru of 12:1 are very worrying

This is my position and pretty simple per my post # 84.
Please do not edit to suit.

I think you are a little rattled mate. Don,t mistake me not saying anything at the time for not knowing what has/is happening. Veiled in allegory like most of your posts???

On the post we can deal with all your bollocks etc etc etc.
Have fun.

SoNiCa

I'm not expert nor tuner. Just wanted to add some quotation from the book I'm reading. I think we should respect to the tuners abilities and experiences.

Jeff Hartman - How to tune engine managments book.

jaytc2003

iTrader: (1)

This however from what I have read was mapped on the rollers, and the afr was taken from the rollers, therefore the afrs can be different when on the road. It was also then checked on the road before being released and deemed to be okay, by a very respectful tuner/mapper
To be honest all these people commenting on this without actually being there and knowing what the engine was doing at the time of mapping, you are not qualified to answer on it as you simply do not know. Like has been mentioned, each engine is different, 2 seemingly identical engines can have totally different characteristics.
I am sure that somebody with Pats experience and knowledge would not let a car go if it was not safe. Pat I imagine makes his living from this, so I dont think it is in his interests to let a high power car go as there would be to much smoke (pardon the pun)

pat

Alan,

If you look at your graph it ends at 6200RPM, Kev's ends at 6750 RPM. Without looking back on the datalogs, I would be unable to say whether we stopped running Kev's at 6750RPM (ie was the rev counter over-reading?) or whether it was actually reved to 7000 RPM. I am certain it would have been setup and verified when we started mapping. To be honest, I would suspect it was taken to 7000RPM and I would put the discrepancy down to setting the gear ratio when we were running less boost and not re-adjusting it when we ran more. Thank you for spotting this potential oversight, I'll try to get the car run again with the RPM interface connected.

Please bear in mind what I said before, that this graph was the result of an R&D exercise to give us information of the relative performance of this turbo against another, we weren't too concerned about absolute numbers, but it would appear to have been used for promotional purposes. If it is indeed incorrect then the torque figure should be 468lb/ft not 485, an "error" of 17lb/ft or 3.6%. If yours had been revved to 7000 (and I'm not saying it was) then your "error" would have been 64lb/ft or 11.4%.

We look at boost and AFR when mapping, not power, so we would not know that the power was falling off up the rev range until we switched over to power and torque, and even if we did we would not lift off unless there was a good reason to. Power and torque are somewhat more incidental than boost and AFR. You can't try to "target" a given power or torque in the same way as you might "target" a given AFR or boost pressure. You also need to consider the impact of gearing. If we had stopped at peak power, ie 5350RPM then we would not be able to check the powerband against gearing. As it stands, 6500RPM seems like a good point to change gear in Kev's, with a 0.72 gear spacing that would drop us to 4600RPM, slap bang in the middle of the torque band with virtually no lag and just riding up the power curve again. As John Banks has alluded to, this makes for an awesomely rapid road car. Given that your engine delivers power in a similar way, I'm sure you need no persuasion as to just how rapid a setup like that can be!

You can run higher tyre pressures to help, that's why DynoDynamics recommend running 40PSI to reduce tyre deformation, but for the most accurate results you are indeed correct, RPM pickup is the way to go. We'll try to run the ScoobyClinic car again after TOTB5 and see how the readings are affected

Re: TEG. I stand corrected. I was under the impression that they didn't use the ignition pickup as a general rule of thumb, and would appear to have been wrong. I offer my humble apology to Town End Garage for making such an inaccurate assertion regarding their services.

Harvey,

I'll stop when a) there is no more request for information and b) there are no longer any unchallenged false statements. You can help a lot with b), it's up to the others to help with a).


ed·it : To prepare (written material) for publication or presentation, as by correcting, revising, or adapting

I did not change anything you wrote, I used a self contained excerpt. This came from the last sentence of post number #84, which in its entirety reads as follows:

I did not edit the section that you are suggesting, I quoted an excerpt from your statement verbatim.

In both cases (the statement I quoted or the one you misidentified as such) the excerpt is unconditional and so requires no context, it cannot therefore be misconstrued outside of its context. You state that AFRs of 12:1 on a road going Subaru are very worrying, which has been proven to be incorrect, or are you now going to try FUD tactics on Alan Garrod as well ?

Nothing could be further from the truth. I was having a bit of fun, something that Tidgy clearly understood I was illustrating just how wrong you are in a light hearted and funny context. Obviously some people got it..... can't say I'm surprised you didn't.

What is happening, Harvey, is that you are using FUD tactics on one of my customers in an effort to get them to go elsewhere. Pure and simple. You can try to deny it all you want but we can see right through it. It is disgraceful but not entirely unexpected.

Sometimes I am economic with the amount of information I reveal. There is a major difference between letting others figure it out for themselves, and saying something that is untrue or has no foundation. When I make an assertion that turns out to be untrue I have the integrity to acknowledge it and, if appropriate, offer my apology. I don't suffer from denial the way some people seem to.

While on that subject... interestingly, someone got in touch with me regarding my assertion regarding the drop gear issue on your car. This is an entire paragraph, so not a simple excerpt that could be taken out of context :

What would you say is the likelihood of both our memories being in error and yours being correct ?

I think we're doing just fine here, thanks. So far, I think your only retort to the information I have given is that it is "bollocks", but there has yet to be any solid evidence posted to support your assertions. Now I know that having said that you'll go away and rally the troops to prove just how wrong I am so I look forward to many an anecdote coming to a computer near me posthaste.

Will try to. You too!

Cheers,

Pat.

AlanG

Thanks for the reply Pat.
I hope you understand where i was coming from in that the discussion on mine some time ago was brought back to mind when i seen SC's graph. With what you had said back then, i find it strange that what was preached wasn't practised.
As for figures, having spent considerable hard earned building a powerful engine with no known outcome, it was only natural human curiosity that i would want to know what i'd worked and paid for.

After the discussion on my results i took stock of comments made with regard to how does the car perform in the real world as against what the engine can produce, and ever since then, i've just carried on and enjoyed the car for what it is.
It's fairly quick on the road and i'll probably still tinker with it, though major money spends are finished on this car as i have other projects on the go.
At the end of the day i've got something which gives me a lot of fun now it's on the road more often than it was during the build. Relying on the mappers ability and not continually monitoring gauges is a big bonus too. Especially at this power level and the acceleration the car gives. You can't watch gauges and drive at this level (well.. i can't anyway)

A little smug perhaps, but i still chuckle when you see the double take bikers give you when they realise you're still "playing" with them! That kind of thing gives me the feel good "it's been worth it" factor!

pat

Alan,

I know exactly where you are coming from. When I said thanks, I meant it! We do try to operate as honestly and as accurately as possible, but noone is perfect.

Indeed. Had I been aware that we were going to use that graph for promotional purposes rather than back to back comparative measurements I'm sure that we would have been somewhat more vigilant. If you look at Tony's graph you'll see it ends around 6900RPM, which seems sensible enough, given the inaccuracy of the rev counter (we would have lifted at an indicated 7000).

Glad that you're enjoying the car now They really are great fun aren't they? Know what you mean about bikes, and it's not smug at all, you've got a very capable car there! I remember with some fondess a time when the only thing I'de "play" with was bikes. These days I get around the country in an oil burner Some might say I've grown old. Some might say I've grown up. Others might say that I've listened to logic. I'de say that the future has no sparkplugs, I'm sure Audi would agree.... if the R10 is anything to go by, anyway

Cheers,

Pat.

AlanG

Likewise.
There had been all manners of dicussions over the years about peoples results from various dynos around the country and what i wanted for mine was a result which would be accurate enough to relate to the spec.
Since Steve set the dyno up as best he can considering the ign pickup was faulty, and in a similar manner to how you've outlined to set up gear detection yourselves, it's as best as can be.

I also enjoy the car now because nobody gives it a second glance, either parked up or on the move. A friend at the Knockhill Time Attack came up to tell me at one point during the day that two young boys had a quick look at the car parked up, nosied inside for a second then seen the badges on the front wings. "UK500?" "Yeah right!!", then walked off in disgust... to look for a big modded car!....

P20SPD

iTrader: (1)

As bizarre as that sounds Alan, thats what i like about mine too, as people at Santa pod said - "whats this thing doing in the pro shoot out?"



Mine is nearly as subtle as yours, but not quite.

Neilo

mine too (when not stickered up....)



they will be coming off in september

not quite in the same power league as you two but i like to dream

AlanG

It's the way to go... street sleeper...

Tidgy

just a note, if your not an expert (as you say yourself) and your being told by several parties including the mapper himself that its fine, then y worry about it and gonna have it changed?

i take a guess you've spoken to someone and they've told you that it shouldn't be like that, have you thought that perhaps they arn't as educated on the subject as they could be, or even perhaps there trying to get money out of you for unecassary work?

Like you i am no expert on the subject, but i know the work Pat carries out and how highly regarded he is, not only in Subaru circles but as a mapper of cars in general, also not only by companies but individuals, so i trust his judgment in the subject along with a hell of a lot of other people, so y don't you?

Neilo

I VERY much doubt that, Sorry.

Tidgy

well its funny that someone with no/very little knowledge of the subject is so worried about a reading which he's being told is fine. how do you get into a situation like that? norm someone telling him it shouldn't be that way.

Neilo

Sorry what i meant was that the person that told him/advised him does not lack knowledge of this sort of thing at all.

Tidgy

so who was it that advised him?

swisstonihasher

More of the same here...

Yes, person I'm speaking with is an expert in the field...rather not say who as dont want "war" going on between mappers etc - it's just not worth it.

Please dont ask anymore about who/what/when/how as I'll not give out that information because of the above.

Tidgy

ok, fair enough, kinda clears up y ask and what caused your concerns, but perhaps you have been given advice that in this case might not be accurate, after all the person your taking advice from hasn't seen the the car or map.

swisstonihasher

Okay, no worries.
Chap I'm speaking with has different ideas re setups and I like what he says...
he also has lots and lots of experience in the field, so really its just a difference of opinion re setups. Will advise more later.

pat

Tidgy,

Given that you aren't privy to the "conversations" behind the scenes it would be very difficult for you to guess. With that information at hand I have a pretty good idea of who it is, and I would concur with Tony that this person's experience and reputation is also very high; suffice to say it isn't Harvey, he's just compounding Tony's fears. I also happen to get on pretty well with this person so I'm not going to say who it might be, and I have no intention of having a big argument on the board. Life is too short. So no need to worry Tony, there will be no "war" going on here!

My issue here is with charlatans, not with other mappers who a) have the right to disagree regarding what AFRs and EGTs are safe and may do so from a point of some considerable experience, which perhaps different to my own is certainly equally valid, and b) who have chosen the deal with the matter in private. I'm glad to see that some people do have some integrity and I respect that.

Tony,

Just one quick thought. Have you asked your new mapper whether he has had a go at mapping a car with ECUTEK on cams that basically have a WRC profile on them ? Don't expect miracles, but there will always be room for improvement. Regards stalling, had the car actually stalled while we were testing it on the dyno, or later on road test, then we would have addressed that problem.... I can't be expected to fix a problem ahead of the car being collected when that problem didn't manifest itself all the while we had the car and therefore I wasn't even aware existed!

Best regards,

Pat.

Tidgy

Fair dos mate, hadn't realised you were in behind the scenes conversations as well.

But i do agree with you that different people have different experiance, tis a discussion for the experts realy about what is and isn't safe to run, and not for people who havn't got the knowledge.

swisstonihasher

Thanks for the reply Pat, glad you agree and we dont have a mapper war - like you say, life is to short.:

Re the cams, will just have to suck it and see...will advise all later.