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Discussion Starter #1
Well I just got done testing two different restrictors I made and here are the results...... Both meet SCCA requirements and both are for use with a 3" inlet tube.... Parts where test with out a inlet tube or filter....... I need some CFD software to mess with instead of turning $30.00 chunks of 6061....

40mm @ 28" H20 = 490cfm
34mm @ 28" H20 = 350cfm

Discuss.....

Larry Parker
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>40mm @ 28" H20 = 490cfm
>34mm @ 28" H20 = 350cfm
>
>Discuss.....

Those numbers look reasonable. The theoretical numbers I got (standard atmosphere) were:

40mm 514 cfm
38mm 464 cfm
36mm 416 cfm
34mm 371 cfm
32mm 329 cfm
30.7mm 303 cfm
30mm 289 cfm

Adrian
 

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Based on some math I did on a spreadsheet a while back (I have it at work, but not here)

40 is good for about 420hp
34 is good for about 320hp

This assumes that you actually BUILD the engine for *and* TUNE for the restrictor.

Matt
 
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I am not much of a fluids person, but I thought the flow would choke based on the diameter of the restrictor. Once that happens, the shape of the inlet doesn't really matter?

bad assumption?

Basically, I'm wondering under what conditions cleaning up the shape of the inlet to the restrictor would do any good.
 

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>
>I am not much of a fluids person, but I thought the flow
>would choke based on the diameter of the restrictor. Once
>that happens, the shape of the inlet doesn't really matter?
>
>bad assumption?
>
>Basically, I'm wondering under what conditions cleaning up
>the shape of the inlet to the restrictor would do any good.

The flow "chokes" when the velocity of the air reaches mach I. This is where nozzles start to work like diffusers and vice versa for air. The purpose of a nicely shaped restrictor is to maximize the efficiency of flow through it at velocities below mach I. A nice venturi will flow more efficiently than just a plate with a hole in it, thus developing more horsepower. however, once you are flowing a volume of air that works out to mach I, there is no shape that can prevent choking.
 

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Correct

Once you reach sonic in the throat, that's all you get....PERIOD

The shape upstream of the throat does not matter very much. The shape downstream is CRITICAL for max flow. Too wide of a difuser cone will create boundary layer separation and cause flow reversal.

Matt
 

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Discussion Starter #8
I wounder if there is cams out there for the 4G63 motor that are optimized for a restricted motor? Also I wounder if one should run a small turbo for the quickest spool then? I assume that the car will not rev far above 6k with the 34mm?

Larry
 

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>I wounder if there is cams out there for the 4G63 motor that
>are optimized for a restricted motor?

Of course there are, whaddya suppose Mitsubishi has been faced with as well as anybody else in International events?

But the first thing is compression ratio.
The thing that restrictor does in strangle what can get thru it, but NOT what you do with that WHICH DOES pass thru.

So Static compression ratios are up to 9.1 to 9.2, opening rates are silly, everything optimised towards a big bang per bang.
So run out and buy some pistons, some real rods, a pair of cams.



Also I wounder if one
>should run a small turbo for the quickest spool then?

Well if you look at photos of underhood things the exhaust housings don't look to small, and the compressor housing look HUGE, but we know the max diameter of the compressor wheel is 6?.? mm, which relative to any OEM Jap comressor wheels looks herkin' humongous.

What I'm not sure of is if the compressor is max Sixty-whatever mm why the huge compressor housings.


I
>assume that the car will not rev far above 6k with the 34mm?

What I've been told is there is no point to rev the fully optimised WRC motors past 5500.
Of course this refers to optimised motors by guys just downn the road from Ford old Boreham operation, guys that spent years at Ford doing software and mapping WRC motors, I'm sure we have guys here in North America who know much better.
>
>Larry





John Vanlandingham
Seattle, WA. 98168

Vive le Prole-le-ralliat
 

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RE: optimised?

re:
"Of course this refers to optimised motors by guys just downn the road from Ford old Boreham operation, guys that spent years at Ford doing software and mapping WRC motors, I'm sure we have guys here in North America who know much better."
Funny you should say this John.
When I was doing chassis work on a Trans-Am 944, the engine work was done by a US-based "hot rodder". When Porsche found out what the output was, they summoned him to Germany to give their guys a seminar. This was after all their ground-breaking 917 work that was "perfected" and their engine guys claiming the 944 would never be made competitive.
If everyone knew everything about engines, there wouldn't be development still going on today. Europe doesn't have the lock on innovation, no one does.
rz
 

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RE: optimised?

spent years at Ford doing software and mapping WRC motors,
>I'm sure we have guys here in North America who know much
>better."
>Funny you should say this John.

>If everyone knew everything about engines, there wouldn't be
>development still going on today. Europe doesn't have the
>lock on innovation, no one does.
>rz
Randy,
we aren't talking about innovation, or at least I'm not and I rarely do, and rarely think that anybody at our skill or competition level needs to worry about innovation.

I'm always suggesting that we would all be better off and WE as drivers would improve dramatically, and sooner if we did think about innovation, and just got down to building things to some "know good spec", and then concentrated on driving and EVEN IF WE DON'T UNDERSTAND some of what or why this or that is correct, just do it and understanding of a different sort would likely follow.

I mean this presupposes that the point of our rallying is to compete, and make good results, and not necessarily our personal education, or to prove how smart and clever we are.
That's one reason why I suggest that people might be pleasantly surprised at their results if they were to build REAL rally cars, straight out of the book, IF they built thourough-going cars especially in regards to the parts which aren't too glamourous: suspension links, steering, mountings for the motor and box, strong hubs and studs, and really strong shells, and the internals of trannies and diffs.

What's the point here?

Europe doesn't have a lock on innovation, but they have had more than 15 years of experience dealing with ever tightening restrictor rules, and it is there that ALL the developement has occured, where the solutions HAVE ALREADY been worked out quite sometime ago.

Our problem isn't trying to figure out how to make a world level motor, that's been done, it just costs money.
Our problem is how to do that at a budget that the average looonie can afford.

Of course when people spend 6,000 or 12,000 or 25,000 on a car to start prepping they are just that much farther from having a car which is a complete package.

Re specifically the solutions to the 34mm restrictor, there are numerous places one can max out the credit card at in the UK which have built WRC motors with the 34mm thing since at least 1995, and I would posit that they may have n acceptable solution from a performance point of view.
All it costs is money.

As to the pocketbook, well it might be cheaper than innovating ones way thru to enlightenment.

And Randy, I'm not picking on you but here we're talking strictly about gravel rally, and the knowledge base here in the US is obviously poor.
In staight unlimited development, especially unlimited type classes, the US has always been able to do some pretty good results.
But:
Look where all the Japanese 'factory' teams are, and look at the results over the years of the Frenchies.
A fair amount of the dominance of English, Swedish, and French design and building is probably from the pre-exsisting knowledge base, much like the incredible dominance of little Finland in driving.

A part which I know well from spending years over there is also the drivers accepting that "this (or that) is really needed, and there's no point in going out there without it" and if that means they buy an older car and make THAT right as they know how to, then older car it'll be.

Here we seem to 'need' newish cars, espically for beginners.
Even if the are painfully stock.


PS, and regards the fruits of German 'development' geniuses, I have worked with German mechanics and known German race bike designers (the Maisch family who made Maico moto-cross bikes which had the performance as good as any 'Factory' bike) and I have to say that as a group they were the most rigid and importantly, the most dogmatic people I have known, short of self righteous Right-wing Republigoons here in the US.
It should be noted that all the serious _RALLY_ development work for the Opel factory occured in Sweden after 1971, and the same for VW.
Opel used the Stockholm company "ENEM" (Nacka Motorrenovering, NM) and VW used Forrsberg Motors in S?dert?lje, 35km south of Stockholm.

It is not surprising that ANYBODY should be able to improve on something that NOBODY in 'der heimat' would concieve of touching.




John Vanlandingham
Seattle, WA. 98168

Vive le Prole-le-ralliat
 

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RE: optimised?

John,
You wrote a lot of words and while trying to watch the rally on TV, made it hard to get the full jist.
But picking one point out of all of it...
I don't understand how you hold two such opposite beliefs;
Learn how to drive on well prepared, suitable equipment.
and
Hate Subaru/Mitsubishi.
The two don't mix well.
Since these two makes have the most up-to-date "cookbooks" of easily obtainable rally pieces, it makes no sense to go out and try to develop a unique car with parts that may be easy to find if you have the right connections or can translate 20 languages. Or pay you, but when I got into this, I tried to copy what Pat did and not re-invent the whole deal. I was impressed with what he did in a couple years and so I gave DC a call and got an idea of what was needed.
This was really a cheap way to go and I can't see anyone doing it for less and getting as many finishes.
---
The Porsche guys DID have test engines and gave up after getting poor results. If They couldn't get results, it wasn't possible.
---
Anyway, on the TV, I saw the Skoda in-car and the tach wasn't labeled with numbers but I heard an 8000 redline if not more. That thing was buzz'n big time. Wonder what they're up to?
---
Also, the guys I hung out with in college called Maicos, Breakos.
----
Not arguing, just pointing out stuff - I can do that, right?
rz
 

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RE: optimised?

A WRC engine normally gets shifted at 5500 rpm(or even lower sometimes) but it will rev to 8500+ before the rev limiter kicks in. That extra rev potential is called "over-rev".

The idea is that if you are accelerating toward a corner and you're at 5500 rpm, it's better to hold that gear and zing the engine to 8000+ instead of upshifting then quickly having to downshift right away as you enter the corner. By eliminating a quick upshift and downshift, power is constanly applied and the car will be faster. Not to mention the added reliability of having to shift x number of times less on a rally.

The circuit racing guys don't have to worry about this beacuse they know the track ahead of time and can choose their gearing so that they always approach a corner close to redline. Us rally folk don't have that luxury though.

Alin
 

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RE: optimised?

>John,
>You wrote a lot of words and while trying to watch the rally
>on TV, made it hard to get the full jist.

maybe you should turn the volume up on the 'clicky clacky TV' this thing here you're looking at.
Or sit closer.

>But picking one point out of all of it...
>I don't understand how you hold two such opposite beliefs;
>Learn how to drive on well prepared, suitable equipment.
>and
>Hate Subaru/Mitsubishi.
>The two don't mix well.
>Since these two makes have the most up-to-date "cookbooks"
>of easily obtainable rally pieces, it makes no sense to go
>out and try to develop a unique car with parts that may be
>easy to find if you have the right connections or can
>translate 20 languages.
Randy, look back and recall, I NEVER suggest people develop unique or whacky cars, especially when they are just starting out or there is no good reason other than the lame "I want to do something unique" when it is only unique because the kid doesn't know the car has been done dozens of times >>>before the whim hit him<<<<.

In fact the reason I push Ford Sierra, Ford Escort, Volvo 240 series
VW Golf, Opel Kadette, and Saab 900 (over the car I have rallied myself (when I do bother to enter events) since 1984 the light strong fast Saab 96) is because so much detailed information is so readily available.

I was not aware that Sububishi and Mistsuburu had something like the 100+ pages of SAAB rally prep or the 175+ pages of the really best source the Ford book:
"Ford Escort MkII Rally Preparation" or the hundreds and Hundreds of pages of detail drawings and photos in the various later Ford books covering Sierras from the 2wd 3 door model thru the last use of that floorpan in the 1997 WRC Escort Cosworth.
Hundreds and hundreds of pages of information so detailed that one can safely and resonably (If one has a pair of eyes and rudimentary intelligence at the level like say an aging Flemo-Hispanic Swedish speaking Saab mechanic)(sorry it might be too difficult for some) look at the drawings and photos and transfer the concepts/designs to components on other cars., if one chose to.
Especially the MkII Escort book which gives lengths on sheetmetal, and gauge, and diameter and wall thickness and diagrams on where to and why to do or site things (OK coupled with the outside knowledge maybe that Virtually every other rwd car was done virtually the same as Ford did the Escort, often eve using the same parts as Ford did or Fords' own parts), detailed instructions on how to make a balance bar mod and dual master pedal box, or showing the first 4 link system then what they found to work better, the 23.5" 4 links etc


Or pay you, but when I got into
>this, I tried to copy what Pat did and not re-invent the
>whole deal. I was impressed with what he did in a couple
>years and so I gave DC a call and got an idea of what was
>needed.
>This was really a cheap way to go and I can't see anyone
>doing it for less and getting as many finishes.
Well you have the misfortune of living where salt eats everything pretty rapidly and so sound shells for cars really suitable such as non rusty 240 Volvos are rarer than entries in George Bushs' Flight log.
And being out there I guess you couldn't see or hear of the exploits of a certain buy from Southern Sweden of Northern California in a really nearly stock (except or gearbox and diff and ring and pinion) yellow Volvo Turbo, a true shop built car coming immediately behind the English and the bought rides.
>
>
>---
>The Porsche guys DID have test engines and gave up after
>getting poor results. If They couldn't get results, it
>wasn't possible.
>---


Yeah its just like when Saab started using the Ford V4, Ford Germany said that it was only possible to get a safe 75 bhp, and the motors would explode at 90bhp, and Saabs first motors were at approx 115bhp and their last in the late 70s hit 200bhp. (Injected for rallycross)

>Also, the guys I hung out with in college called Maicos,
>Breakos.
Cause they heard somebody else say it.
The only thing thast was below average was there wheel strength as stock, the 2 sons Hans Maisch and Peter who I knew better both used wheels from "Wheelsmith Engineering" in LA.
And their answer was "If you do EVERTHING EXACTLY as it is in the service book, you can win a World Championship with this bike"

>----
>Not arguing, just pointing out stuff - I can do that, right?
>rz





John Vanlandingham
Seattle, WA. 98168

Vive le Prole-le-ralliat
 
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