250 bhp from CIS ?

[911st]

Great link. I would look at the euro WUR closely. I think it may have an acceleration function to it that lowers control pressure when manifold pressure drops under acceleration. This would help throttle response.

If that is what it is and it is not on the US WUR I would work hard to get one.

Remember the frequency valve / Lambda is only on the US 81-83 heads.

I believe unplugging the O2 may disable the Lambda function but I am more in tune w Turbos. The lambda should be taking out of the loop at WOT.

I suspect there is a cheaper way to fix the lean condition.

[Bill Verburg]

To get 250hp out of a n/a 3 liter you need to raise compression, use a stronger bottom end, use some nice lumpy cams, use a nice tuned exhaust, use either carbs or itb fi

The factory got 250hp@7000 fom their SC/RS in touring trim, 270@7600 in rally trim

the advantage of carbs is mostly their insensitivity to intake tract pulsation which is the limiting facor w/ cis

[911st]

Or make it a 3.4 w C2 cams & exaust.

[safe]

Originally Posted by Bill Verburg

To get 250hp out of a n/a 3 liter you need to raise compression, use a stronger bottom end, use some nice lumpy cams, use a nice tuned exhaust, use either carbs or itb fi

The factory got 250hp@7000 fom their SC/RS in touring trim, 270@7600 in rally trim

the advantage of carbs is mostly their insensitivity to intake tract pulsation which is the limiting facor w/ cis

And the SC/RS used a Kugelfischer MFI instead of the CIS.
http://www.racecar.com/edmondharris/parts/product_detail.asp?ProductID=435

[Bill Verburg]

Originally Posted by safe

And the SC/RS used a Kugelfischer MFI instead of the CIS.
http://www.racecar.com/edmondharris/parts/product_detail.asp?ProductID=435

yes, "itb fi"

[davidbir]

Thanks guys, but not relevant to this thread as nice as the thought of fitting Kugelfischer FI is

I am a little confused:- 912ST, are we talking about fitting a Euro Fuel Distributor or a Euro WUR (Can we agree to call these a Control Pressure Regulator-CPR?), or both?

[DARISC]

FWIW, on my '82 RoW (204 hp, 9.8:1 cr from factory), I put SSIs & a Dansk 2 in/2 out ss muffler and believe it makes, maybe 220-223 (not rw) hp? Haven't had it dynoed, just speculating from what I've read on numerous threads and elswhere.

[911st]

Originally Posted by davidbir

Thanks guys, but not relevant to this thread as nice as the thought of fitting Kugelfischer FI is

I am a little confused:- 912ST, are we talking about fitting a Euro Fuel Distributor or a Euro WUR (Can we agree to call these a Control Pressure Regulator-CPR?), or both?

Someone has to have put this together already.

I am using my knowledge from my Turbo w CIS.

I suspect the fuel head is not a in the way of making HP.

The base or starting point for the Air Fuel ratios starts with the adjustment on the fuel head. This richen and leans every point along the A/F curve.

The WUR or CPR as you say, along with the profile of the cone around the metering plate determine the amount of fuel delivered relative to air flow.

Messing w the cone is kind of difficult.

Playing w the CPR is pretty easy. Lowering control presser or CP lets the metering plate move quicker and it will get progressively richer as you move up the rpm range. The reverse is true.

If there is a circuit on the euro WUR/CPR that lowers CP with the loss of manifold vac upon opening of the throttle plate (acceleration), you will have much better throttle response.

Look into this and if the US WUR/CPR dose not have this circuit or has different at rest CP, this will be what is needed to get the most out of an SC.

The Lambda circut may have to be alowed for. It will help get better MPG if you let it.

Is there a circut that trigers WOT? If so, this turns off the Lambda smog adjustment. You could substitut an adjustable Vac switch to triger this earlyer w acceleration.

If not put a vac switch in line of the O2 to take it out w acceleration.

Or, just upplug the O2 and the system will just lock up and you can tune around it.

I love CIS.

Make sense?

[davidbir]

I'm a Limey--what's a "fuel head"?

Otherwise, yes, mostly...

[911st]

Sorry, I must be having a senior moment. What do you call the thing that the fuel lines come out of to the injectors. I have alwas called them the CIS fuel head but I guess you call them the distributors or somthing.

[Bill Verburg]

Originally Posted by davidbir

Thanks guys, but not relevant to this thread as nice as the thought of fitting Kugelfischer FI is

I am a little confused:- 912ST, are we talking about fitting a Euro Fuel Distributor or a Euro WUR (Can we agree to call these a Control Pressure Regulator-CPR?), or both?

au contrere
to get an honest 250 ala SC/RS you must put more
1) fuel
2) air
through the engine in a shorter period of time.

A fuel distributor takes care of the fuel, but where's the air coming from?

You need more air than the stock intake/cam can deliver and you need more revs than the stock bottom end can deliver.

You can tweek a cis engine for more power but it will always be limited by the ability to ingest and process air and the ability to rev.

[911 tweaks]

it is called as just what it does... "fuel distributor"

great thread... I agree that their must be a way to make CIS work to allow more hp and not have the air pulsation issue when you go more cam = more aggressive than 964 cam... anyone care to share their secret ???
Bob

[Kroggers]

Micke Svens (Spezialmotorer in Sweden) has built a 600Hp 930 CIS Engine.

[fred cook]

Ok, I think we agree that to make more power then there has to be more air and fuel moving thru the system. Also, there is the problem of pressure pulses messing with the air intake stream. Here are some "out of the box" thoughts:What if the engine was set up with two throttle bodies, with one feeding each side of the engine (ie, cylinders 1,2 and3) but using one fuel distributor? The fuel distributor could be operated off one of the throttle bodies, or be placed above and between the two tbs with a connecting mechanism that would allow both to apply lift to the control plunger or, 2 fds could be used with 3 ports plugged on each.* As long as the compression is even each throttle body would deliver the same amount of air to it's 3 cylinders. As previously mentioned, the fuel distributor probably has the volume capacity to deliver sufficient fuel to make the desired additional hp. And, building the intake this way would likely eliminate the cross pulses in the intake tract. Now (maybe) you have an engine with CIS injection but making more horsepower. Now to figure some way to get the engine lid to close!

[safe]

I think the metering plate is the biggest obstacle in the CIS to produce NA power.
You could probably use a much more aggressive cam than the 964, if you raised the idle to ~2000 rpms and made sure it cleared the pistons.

It would be interesting to find out what kind of cams you can use and what power you could extract with the CSI->EFI conversion kit by tbitz.

[safe]

Originally Posted by Kroggers

Micke Svens (Spezialmotorer in Sweden) has built a 600Hp 930 CIS Engine.

Several I would say

But his builds are not cheap, and extends far beyond a little CIS tinkering.
I talked to a fellow a few weeks back and he had a -87 930 producing 520 hp at only 1 bar (14.7 psi) of boost!
That, in a perfect world, translate into 260 NA hp from a 3.3 liter engine.

[davidbir]

Presumably the turbo 'smooths out' the intake pulses in a 930?

Bill Verberg--I was trying to keep the thread on CIS
I think we all realise that power depends on "more in = more out" but the SC bottom end is strong enough for 250 hp in standard form surely? We also seem to be concentrating on 'bolt on' conversions such as SSI and different/modified CIS components--I suppose cams can just slip under the wire here.... Once you start replacing the P&Cs you are into major work/expense which I (and many others) am trying to avoid!

[Bill Verburg]

Originally Posted by david bir

Presumably the turbo 'smooths out' the intake pulses in a 930?

Bill Verburg--I was trying to keep the thread on CIS
I think we all realise that power depends on "more in = more out" but the SC bottom end is strong enough for 250 hp in standard form surely? We also seem to be concentrating on 'bolt on' conversions such as SSI and different/modified CIS components--I suppose cams can just slip under the wire here.... Once you start replacing the P&Cs you are into major work/expense which I (and many others) am trying to avoid!

I'm just pointing out that cis & 3 liter n/a are not conducive to much more than ~225.

You can get more air through the engine w/
1) headers
2) displacement
3) revs & cams & valves
4) turbo/super charging

the stock 3l bottom end is not hp limited(at least at the 250 level) it is limited wrt to revs, 7k is about it.

headers help but w/o a commensurate improvement on the intake side can only do so much

displacement is a no brainer, plus you improve combustion efficiency by getting rid of the unfavorable cis top pistons and raising compression, but you are no longer dealing w a 3l are you?

additional revs entails not only a stout and lw bottom end but also cams, valves and intake that work as one to process additional air. Fuel can be taken care of any # of ways but moving air is the key. Again cis is limited by it's barn door flapper and the reversion pulses that are increasingly forceful in both the intake and exhaust when cam duration and lift are increased, cis just can't handle it gracefully. You can band aid it w/ raised idle but how high an idle do you want to live w/?. A turbo supercharged engine doesn't use happy cams it packs the intake tract w/ high pressure air, this also moves more air through an engine. cis & turbo/supercharging are a fairly happy couple because of the mild cams used, the factory continued to build cis turbos long after they abandonded cis n/a.

I'm sure that you dreamers don't want to hear any of this but there is already a 34yr history of folks trying to make big n/a power from cis, take a few pointers from this history and go down one of the proven paths.

If not, well best luck to you, we are all pulling for you to suceed.

[DARISC]

To all on this thread (who don't already know this):

Re Bill Verburg; I know, I know - the guy's only got a few more than 14,000 posts and sounds sooooo logical and well informed! Well, you know how the internet is; you can be anybody you say you are, moderator, have tons of knowledge and experience, yada yada yada...

The problem with the vaunted Mr. Verburg is......he DOES have tons of knowledge and experience (and a fair ammount of yada yada too).

This whole CIS thing has been through the wringer here many times over the years and as far back as I've been looking in here, this Verburg character has patiently explained "about CIS", repeatedly.

Lively discussion can be fun and edifying, but in this case, Bill Verburg's input is the definitive stuff (incontrovertible).

PS - I think he hates CIS.

[Bill Verburg]

Originally Posted by DARISC

PS - I think he hates CIS.

I don't hate it, it is what it is. Good for a relativly stock, mildly tuned motor or a turbocharged motor. But i also learned of it's limitions. I lived w/ cis on my C3 from '76 thru '94 it worked well and was by no means the weakest link in the chassis/driveline chain. DME is somewhat better but still limited as far as intake tract air handling.

I've been investigating other efi systems of which there are many excellent choices, but all work best w/ itb's.
Which is not to say itb's are necessary. There are many ~300 hp Motec 3.6s running w/ only a single central throttle body, but they have also ditched the stock air metering method.