Guy, if you can create the page with pics linked to your PC, then if you fancy e-mailing all the pics I can upload them to http://daveg.hankscorpio.net/albums/GCRE and you can then place the same URL in front of the file names, would that help? I could also add a "watermark" type image over the top, eg: (c) GCRE 2011

mm, thanks guys for the offers and advice. Actually I have some 40Mb of photos and flow data on this head. None of the present options are very workable. Photoshop not a chance, just tried it, be glued to me laptop for days.

G

What is with this fetish for high revving engines? I know that in the world of non-turbo engines, you need revs to get power, but the whole point of a turbo engine is that it doesn't need revving so high

FWIW I revved my 20vt to 8000rpm, and unlike most people's road engines, mine was hitting 8000 every few seconds, not once in a while. Equally FWIW my view was that I shouldn't be driving a turbo engine with all the characteristics of a mega-power Integra R engine, ie peak torque at 6800rpm, peak power (and still rising) at 8000 - all restricted by hydraulic lifters

My new engine, which for various reasons sits on the kappa subframe but with nothing connected up at all should right most of the previous wrongs - we have solid lifters so I can rev it if really need be, more to save a qucik chnage up then down before a corner, or if the kappa's 6th gear proves too low (8000rpm = 167mph) - but have had cam timing set up to be a little more docile, to develop torque from lower down

My final word - the 20vt develops 220bhp in standard form, certainly when my 20vt k coupe was new, it averaged 30mph without too much issue so imagine a lighter Fiat Coupe should be equally capable. By comparisom, the 16vt developed anythingf rom 190-215 depending on standard installation, and fuel economy was at least 5mpg worse. Seems to be as stock, the 20vt must be the more efficient engine, and as it was never built with competition in mind, maybe its not surprising that it is considered less tunable. But I suspect there are more big power 20vt engines running in the UK than there are 16vt?

"What is with this fetish for high revving engines?"

Trevor, it may be that, but certainly the rpm you want/need to run to kinda depends on your overall drivetrain gearing doesn't it?

G

I don't think Guy knows about our magic 3rd gear

Guy, PM'd you on how you can easily and quickly upload them to my server. I'll take care of them.

no point in a 20vt turbo engine which is used purely as a road car having all the power at stratospheric rpms as the gearing is very long on the fiat coupe, far better to have a fatter power band in the mid range where you will mostly be using the car

in standard form the gearing on the coupe gives about 106mph in 3rd at the redline, extend the redline to 8000rpm and your max speed goes up to something like 120 in 3rd, very impressive but not really useful on the road in everyday driving, unless you shorten the gearing, just my 2 cents worth

thanks once again to all who tried to help me re upload I have followed Kayjey's lead so fingers crossed.

G

Guy

Suspect I might get better reliability from a lower revving engine, and more torque low down will make it more driveable. I've already changed the gearing to suit the old engine, but with BTCC moving to 18" wheels with the NGTC, I might have to do the same to ensure a steady supply of cheap tyres - and that will raise the gearing that bit more

Masses of midrange torque is great but it's a gearbox killer (especially true on the integrale). Where as a similar torque spread more evenly and a lengthy rev range makes better power for longer.

An extreme example might be the small cylinder capacity and crazy hp / rev range of the old F1 turbo's. Of course it depends on what the car is used for.

Guy, I have been running the above statment over in my mind ever since it was first talked about on this forum I belive some time ago now, but I just don't get it. Maybe I'm not clever enough but this is what I don't understand . . .

Just forgeting the speed of sound bit for a moment, on an N/A unit at IVO the cylinder creates depression which means the atmosphere has to be at a higher pressure. Similarly on a turbo unit the depression of the cylinder at IVO is lower and the pressure in the plenum is above atosphere, since pressure always moves from high to low it follows that the two situations are the same albeit at a different (higher) ratio on the turbo. We could call a plenum an atmosphere and an atmosphere a (very big) plenum.

As I understand it sonic waves reflect in different signs off a change of area, most noticably an abrupt one and even off a closed ended pipe as a positive. The abrupt change of area at rampipe, open to either a large plenum area or the area of atmosphere (forget atmospheric pressure just atmophere) cause this effect.

Unless I am missing a massive piece of information, help me understand your statement. An organ pipe needs 'wind' (as they call it) to function or air moving from high to low pressure within that pipe. The pipe's top end open to atmosphere reflects a negative and then a positive and a negative and so on (Agian, forget the actual sound produced) but the principal of the pulse moving is the same.

I know a race engine is'nt a musical instrument but the organ pipe could represent an inlet tract and the only big difference is the valve is in there opening and closing that creats the source of the sonic movement.

So am I far out on that ?


Rich

I don't think it's that precise part of it that Guy disagrees with because I know he has said that pressure wave activity is present and un helpfull in a badly designed exhaust side of a turbocharged car and that is, is most cases a higher pressure medium than the inlet side, like as in a 2:1 backpresure ratio. So if they can exist there they can exist at any gas pressure.

It was only really because the topic of which would do best in an ultimate build that rpm has been brought into it, sorry to stray off. I would though suggest that a ability to hang onto longer rpm shouldn't affect how well the car performs at lower levels, NA I can see reasoning but on a turbo build there should be a broad range. Not to say that there isn't often a glaring restriction/mistake which spoils what is possible. It helps if you can prop up the areas likely to be weakest.

on boost the entire inlet tract is above cylinder pressure at IVO so no outgoing negative wave develops at the valve throat, the charge just moves straight into the cylinder.

OK, I'l think about it some more. The whole subject N/A and turbo, inlet and exhaust interests me so I shall research further.

Perhaps GC would be kind enough to point us in the direction of a bibliographic citation or two where we can read up on this, as I can't find any references (all references I have found support the theory that induction length does indeed have a tuning effect on turbo engines) and he must have read or learnt it it somewhere?

I think you'll find that Guy HAS written down an awful lot of what he knows - it's in his book....

Perhaps you don't know what a citation is. I'm sure GC does.

Steep learning curve eh Martin!

G

Not sure what you mean by that...

I first started looking in detail at supercharged and turbo engine applications over 13 years ago, so a rocky learning curve rather than a steep one might be a better description.

As I said above, all the references I have - Corky Bell, John D Humphries, Heinz Heisler, plus personal contacts in the upper echelons of the UK engine and turbo specialist companies who have been kind enough to talk to me, plus the results of many a Google search - are quite clear that inlet wave tuning is valid on a turbo engine. Engine simulation software also supports the theory as does personal experience in terms of dyno plots.

I just can't find any evidence contrary to the fact that waves exist in the inlet runners, just as they do in a N/A engine, and can be used to good effect by inlet tuning, so I'd be happy for you to point me in the right direction of evidence that supports this alternative view.

We'll just have to agree to differ!

G

[/quote]
Corky Bell, John D Humphries, Heinz Heisler [/quote]

I found Heinz and added a book of his to my wish list on Amazon (what level of reading is he?hard going?) but couldn't find J D Humphries, any pointers?

Does Corky talk about pulse tuning FI? I can't remember which bit if he does.

A good book I lashed out on recently has a whole chapter devoted to it, mind boggling book that weighs heavily towards mainstream manufacturers and their motives. Nice to see its more than doubled in price since I bought the last new one
https://www.amazon.co.uk/Fundamentals-Tu...8551&sr=8-1

I found Heinz and added a book of his to my wish list on Amazon (what level of reading is he?hard going?) but couldn't find J D Humphries, any pointers?

Does Corky talk about pulse tuning FI? I can't remember which bit if he does.

A good book I lashed out on recently has a whole chapter devoted to it, mind boggling book that weighs heavily towards mainstream manufacturers and their motives. Nice to see its more than doubled in price since I bought the last new one
https://www.amazon.co.uk/Fundamentals-Tu...8551&sr=8-1

[/quote]

Automotive Supercharging & Turbocharging Manual - John D Humphries - Haynes - ISBN 0-85429-880-0

http://www.amazon.co.uk/AUTOMOTIVE-SUPER...1029&sr=1-1

I'm getting my Bells confused! Corky touches on longer verus shorter inlet runners but without maths, A Graham Bell covers more in Forced Induction Performance Tuning http://www.amazon.co.uk/Forced-Induction-Performance-Tuning-H691/dp/1859606911

Heinz can be hard going in parts (Chapter 3 on engine balance and vibration did my head in!), but it is generally easy to read I find.

I bet this one will do your head in ! -

Book @ amazon

Ta muchly

Not sure what to think, because of the one review:-

this is a very fundamental book on the subject, however, it's easy for a beginner to follow. it lacks the basic equations and theories that describe the intake and exhaust flows. if you are a graduated student, stay away from this book. you would have learned more from fluid dynamics 101 (if you were awake in class)

Do you have it? Have you found it useful?

That's a doddle compared to the Baines book, Baines whistles over my head in the main but that's what repeat readings for. Good book the Smith/Morrison one though, often pick that up.

It's a NA book so it's with care you need to relate it to FI.

I like it because it helps me to think like air does in an engine.

No, but Iv'e been very tempted. The review sounds dissapointing yet a few people on race engine forums around the world have said it's very good.

Which one sorry ? the Smith / Morrison