How much power do you have? How did you get there?

[Craig 930 RS]

They sure are. With Hoosiers, they are quicker per lap than my 930 -

[RarlyL8]

A/F ratios are A/F ratios.
If you can achieve 12.2:1 without a fuel head mod then all you are doing with the fuel head mod is wasting gas. There is no sustained boost on the street so the engine does not need to be fuel cooled.
Race cars and high HP engines are a different animal.

Optimally you should tune all 3 points of the WUR so an RPM switch is not needed. I would never presume that boost hits at the same RPM in every gear in every situation.

I think I've mentioned in the past that a friend - with absolutely stock internals; ie everything from stock P&Cs, 7.0 CR, stock 930 heads and manifold - but with cams, B&B headers, muffler, & stock K27 - achieved 360+ RWHP.

What boost level was that at? My engine, when dynoed in that same configuration, put out ~320RWHP @0.7bar boost.

Lots of apples and oranges here. The original post asked for formulas to achieve HP. There are many different ways to achieve the same HP levels, let alone varying degrees of power. Pat's SC engine lays down the same power as an early stock US 930 while Craig's monster CIS engine puts down more power than some of the EFI motors. Hell you could run a stock engine on toluene at 1.5bar and hit 400+HP (for a little while - ha!).

[Jim2]

Ramblings... (Craig's post with the Holcomb dyno chart)


I'm sick and tired of..................




930 cylinder heads! These engines are crying for some 993 heads, BIG intake manifolds, and BIG headers. At 550cc per cylinder my ports and scrap headers are about the same size as a stock Austin mini (the early one!). HP requires breathing regardless of turbo or NA and I feel my motor is simply being choked off. I feel this is the biggest difference between the majority of us, and the "Holcomb" motor dyno chart.

Years ago I got my hands dirty building four cylinder turbo motors. Some of my friends were running in the territory of 190 HP/Ltr at very modest boost levels (Under one bar). This was a good display of well tuned engines with a solid foundation of the fundamental components required to make HP.

My car is making 130 HP/Ltr nearing one bar. The Holcomb motor makes somewhere in the range of 180-190HP/Ltr at one bar.

Anyone have some "good" heads laying around?

End rant!

[wcarson]

For whatever its worth:
351 rwhp/ 348 ft-lbs on a dynojet dyno (approx 400HP crank)

KKK K27-7200
CIS with IA fuel head mod
0.8 bar
Elgin SC 330 cams
Kokeln IC
Ported heads
Euro heat exchangers with borla muffler, no cats
EBS valve springs
ARP fasteners

The car is an 82 non sunroof 930. It's fast, although I am sure nothing like the EFI set ups. My biggest street victory was a C-5 Z06 on the freeway from 65-140mph before we had to brake. I was maybe 3 car lengths ahead. I am sure that a new ZO6 would hand my butt to me. I guess that's was EFI is for though......

WKC
San Diego, CA

[Jim2]

I need to "un-subscribe" before this starts costing me more money!

[Craig 930 RS]

Very true. There are engines which never need an IA fuel head.
#1 manage the fuel you have via adj. WUR, and check AFRs.
-------------
"Optimally you should tune all 3 points of the WUR so an RPM switch is not needed. I would never presume that boost hits at the same RPM in every gear in every situation."

Without the fuel head it may be theoretically possible.....but w/o the head you normally run out of fuel up high when the WUR is tuned for low to mids. RPM switch is required for a proper job - at that point, after everything el$e, scrimping on leaving out the low cost RPM switch is just foolish.

Adj WUR & RPM are a must, with the fuel head optional dependent upon the resultant AFRs.

Sounds trite, but a hi-po 930 for the everyman just does not cost all that much.

[RarlyL8]

The RPM switch is a device that allows you to move an entire range of function. It has no provision for fine tuning.
You are talking about high HP applications, those above 375RWHP. Those issues simply do not apply below that power level. This is not a theory. The RPM switch does nothing to add fuel, it simply delays the onset of boost enrichment. I don't have one on my engine and the ratios are perfect.

Back to our regularly scheduled program....

Are there any patterns forming? How about a simplistic build guide:
255 RWHP - stock Euro
300RWHP - turbo, cams, 0.7bar
350RWHP - turbo, cams, intercooler, headers, 1.0bar
375RWHP - turbo, cams, intercooler, headers, 1.0bar, head work
400RWHP - turbo, cams, intercooler, headers, 1.0bar, head work, fuel system mods
450+RWHP - all of the above plus EFI

[Craig 930 RS]

I like the idea of the guide Brian has, but you will not need 1.0 bar to get 350 hp - and I personally would not do 1.0 bar without fuel modifications.

The Brian Leask adjustable WUR allows 3 adjustments:

Cold start
Warm run
Full boost enrichment

The RPM switch is an excellent idea because you do not need the FULL, and I mean all hell breaks loose full gush fuel dump at 3,000 rpm, the point at which modern turbochargers produce FULL BOOST. It is 'tunable' by inserting an rpm plug of varying RPM full boost threshold. Mine happens to be 5,200 rpm - up from 3k stock.

Again, there are variables which need to be taken into account here.
If you require the fuel head THEN wish to take that extra step in order have a higher HP 930 engine (yep, easy to do and not a stretch from a mid-300s hp engine), then an RPM switch is also required.

So, to "get there" HP-wise, I'd suggest the WUR 1st in conjunction with the K27 HFS, headers, 8 bar and probably $$$ cams.

For a street beast, the leap to safe, high HP is a tiny step dollar wise from a 320-hp car.

And don't forget that full CIS checkup prior to that HP bump - including injectors!!!

[patkeefe]

Regarding Craig's point on the IA head:
I realize that my SC and the 930 are a bit different, but principally the same. I was unable to get AFR's below 13:1, even with the old homemade adjustable SC WUR. The IA mod allows a lower AFR (they told me they could get a point of AFR with the mod on my SC fuel head, and they did). The Brian Leask WUR seems to make the system way more compliant and tunable. I tend to agree with Craig on WUR first, then fuel head mod. I have no experience with Brian's RPM switch. I would like to know what the difference is between the RPM switch, and the boost threshold adjustment on the WUR.

I can say that my street AFR's are just right, but I was 10:1 AFR on the track for the past two days. My little engine was on boost basically all the time, except for the corners. I may be able to tune that with the WUR. I'd like to know what you guys are seeing on the track.

[RarlyL8]

The RPM switch is an excellent idea because you do not need the FULL, and I mean all hell breaks loose full gush fuel dump at 3,000 rpm, the point at which modern turbochargers produce FULL BOOST. It is 'tunable' by inserting an rpm plug of varying RPM full boost threshold. Mine happens to be 5,200 rpm - up from 3k stock.

That is precisely the area I am typing about. That 3000rpm dump point is not an absolute and can be tuned out. An rpm switch does not reduce the dump, it just moves it so that the extra fuel dump is in an area where it can be used so it does not show up on the graph as excessive. It does work as it was designed, just not the way I would go about getting there due to the variables seen in boost threshold. I prefer to control boost enrichment by boost signal, not by rpm.

The above "guide" is very simplistic. There are many ways to achieve the same HP levels.

[Craig 930 RS]

The fuel head will cost $500-ish, you may not need it, and you must install (not a simple job, drop the engine)
The fuel head allows a known and absolute margin of safety that can be 'dialed back' using the RPM switch and 3 way adjustable WUR.

$500 (?) for the head, $300-ish for the WUR, and not much at all for the RPM switch setup gets you all the way there for virtually guaranteed safe AFRs. Just judge if you want to jump all the way in dollar wise all at once when you *may* not need to.
High HP 930 engines almost always need the fuel head anyways, so that is the route I took towards the:
"How much power do you have? How did you get there?"
If high HP is your goal, I'd do all three. The fuel head may not be required, but for me it was.

As another aside - 'getting there' is fairly easy due to Brain Leask's WUR/RPM instructions.
Brain has written some of the very best manuals I have ever seen.

[DSPTurtle]

How can we get a copy of Brian's "manuals"?

[look 171]

Originally Posted by RarlyL8

It would be difficult to gets past 350HP without head work. That is where I think Sandman's will dyno unless porting was done during the twin plug process.

The modified fuel head is not needed until your current fuel head runs out of adjustment and fails to maintain 12.2:1 A/F on boost. That happens somewhere around 375RWHP.

Head work was done by the PO. Maybe I need to take a look..I am in So Cal, so I didn't it was necessary to adj the wur all the time.

[WERK I]

Originally Posted by look 171

..I am in So Cal, so I didn't it was necessary to adj the wur all the time.

Warm-Up Regulator is somewhat of a Bosch/Porsche Factory misnomer. It has absolutely nothing to do with the type of climes you may live in. The accurate term would be Fuel Pressure to Fuel Distributor Regulator. The Auxiliary Air Regulator is more like a Warm Up Regulator. It's only necessary during the cold start or near cold start engine startup.

[911nut]

Originally Posted by Craig 930 RS

I personally would not do 1.0 bar without fuel modifications.

This is Don Hollinigs' car. He's getting 12/1 AFR's with a .9 bar spring and no fuel head mods:
http://www.youtube.com/watch?v=0yN21pTCAwA&mode=related&search=

[RarlyL8]

We talk a lot about adjusting the WUR because most of them are very old and out of spec or used on modified engines. Adjusting them is usually a one-time deal. You check your A/F ratios, adjust if needed, and lock it down.

Could be that the WUR name stuck (pre-911) because the cold pressure function is most noted when it falls out of spec and your car becomes difficult to start. The dealerships and shops simply tossed it out and installed a new one. I guess we should be thankful that Bosch did not incorporate the WUR into the fuel head.

[c2turbo]

590 RWHP (680 crank hp) 1.1 bar pump gas with plenty of room left just ran out of turbo on the top end about 6400rpm's


91 C2turbo
3.8l 964 based block ( started life as a RUF RCT )
JB cast iron CYL
GT2 cams
JE pistons
Carrillos rods
JGS wastgates and blowoff valves
GT28rs twins
DTA EFI (tuned by wayne ) TPG

BLA BLA BLA
oh yea the car weight = 2873 with 1/4 tank
Car does not even breath heavy and want more boost

http://www.youtube.com/watch?v=PbtvC39I9Qs

[Craig 930 RS]

Sweet Mother of God.

[patkeefe]

That gauge is really slick. I could replace my six gauges under the dash with that!

[c2turbo]

Thank you

www.inyourfacegauges.com