Andreas,

The 2.4-S and RS distributors are not the same:

2.4-S ... 0 231 169 005 (or 010)

2.7-RS .. 0 231 169 011

Different curves ... the factory RS is NLA and has been superceded with:
0 231 184 004 or 911 602 031 FX

A 2.7 911-S dist. is close ... 0 231 184 001

I've been around this block a couple of times in the last few months :(

I ended up still using my 2.4-S until I get it recurved.

Greg,

I'll check my receipts when I get home, but what I remember is...
I sent my pump in May '03 and got it back 7 weeks later with a RS cam change and recalibration for about $750 ... and Matt B. did the throttle bodies for about $800 at the same time...

Could it be that Gus has gone up THAT much in 13 months?

Cheers,

I spoke with him a couple months back regarding this very issue - converting a 2.4S pump for a 2.8. His response was about $700 to do the conversion and that the RS cams were about $500 (the euro is a bit weaker since).

Sounds like the answer is yes! :(

Greg,

Just checked my records...

Matt Blast was $887.50 for throttle bodies complete..

Gus was $748.00 on 8/14/03:

Cam - 450.00
Labor - 280.00
Ship - 18.00

Now, this was a pump that Gus had rebuilt awhile ago and was running perfectly. So, the labor was to R&R the cam and recalibrate the pump only... no rebuilding at all.

Hope this helps... AND... hope this doesn't get back to Gus
If-ya-know-what-I-mean ;)

Chuck, that's good news! There's hope next winter's project will only cost a small fortune! ;)

2.4 S pump on 2.7 RS spec motor
 

Gus is right.
The only difference that I can find between these two pumps is 1 cc of flow at each end. 12 - 13 at idle and 63-64 at full throttle. The RS also has larger idle screw holes in the butterfly housings.. 3 mm 2.4 "S" 2.7 RS 4 mm.
On the dyno I can't see the difference.
These MFI engines run so rich everywhere that the problem is usually making it run leaner not richer. My experience with the 2.4 "S" engine is that it gets 16 miles to the gallon. By anyone's standards that's a lot of fuel.
We ran a 2.0 E pump on a 3.0 twin plug MFI engine that made 280 hp and the pump was stock. During one race the pump rod came loose and the pump got so rich we got 2 miles to the gal. Perhaps enough fuel to make 7 or 8 hundred hp.
Run the "S" and tune for good fuel mileage and that's all you can do.
Remember "perfection is the enemy of the good".

My Memory just isn't what it once was.

Correction: 2.4S 13-14 cc @ Idle
2.7 RS 13-14 cc @ Idle
2.4S 49-52 cc @ Full
2.7 RS 53-54 cc @ Idle

Just got off the phone with Gus. He told me to expect to pay around $1400. I also asked him about S vs. RS for the 2.7RS application and he felt that the space cam upgrade needed to be done. Still, Henry's comment about purposely running a little rich sounds right to me. Decisions, decisions. :confused:

This is really interesting. I'm in a similar boat as Jim, except I
have a 2.4S pump and a 2.8 liter engine. So ...

What exactly does that mean? Is this the volume of fuel pushed
out of the pump into each line per plunger stroke?

My Memory just isn't what it once was.

Correction: 2.4S 13-14 cc @ Idle
2.7 RS 13-14 cc @ Idle
2.4S 49-52 cc @ Full
2.7 RS 53-54 cc @ Idle

What this means is cc of flow / cylnider @ 1000 strokes of the pump. In the pump there are 6 small pistons and a crank shaft ( looks more like a cam.) As the engine turns the pump turns 1/2 it's speed. For every pump revolution there is one stroke of each piston.
That should be enough information to make us all go crazy.

Maybe. The following is sure to push us over the edge...

How much fuel does each cylinder need per revolution?

Hopefully this isn't overly naive, but here goes.

~2400 cc / 6 = 400 cc per cylinder. Assuming 14:1 AFR (by volume) yields 26.7 cc. Same calc for ~2700 cc yields 30 cc. So, the 2.7 needs ~3.3 cc more fuel each stroke, the 2.8 almost
4.5 and and 3.0 a whopping 6.7 cc more each stroke to maintain
a 14:1 AFR.

If logic is sane, then that 26.7 cc delivered to a 2.7 would result in a 15.9 AFR, 16.5 AFR in a 2.8 and 17.8 in a 3.0.

Ok, so why doesn't that 3.0 blow up at full throttle ... ?

I'll make this a little more interesting.
These number are space cam flow numbers only.
The idle rpm for the pump is 400.
The full throttle rpm is 2000.
Given that the pump runs at 1/2 the speed of the engine that means these numbers are only pertinent between 800 rpm and 4000 rpm. This is the theoretical operating range of the governor. The main ingredients in the governor are the space cam and two flyweights. Once you get to 4000 the flyweights have no effect so the space cam is no longer adjusted by the rpm just throttle position.
Chew on that for awhile.

The 3.0 didn't blow up because the the pump was adjusted to a rich enough condition to make it happy. The point of the story was that the pump when improperly adjusted gave us 2.5 miles per gal. Which means we could have adjusted as rich as we liked.

I can't believe that MFI works as well as it does .... (for power, not for economy) I guess it is because gasoline engines are somewhat flexible in the A/F ratios at which they will run well.

Kobalt, you're making the verrrrrry long reach that all of the engines have 100% VE from 4000 RPM up. Due to porting, relative valve sizes and stuff like that it just may not be the case.

I believe that was the case for example with the 2.7 and 3.0 RS's. The HP/liter ratio decreased as the engines go bigger even though the only thing that was changed was the capacity.

Model / HP-liter / Peak torque RPM / Peak HP RPM / liters-minute at peak torque

2.4 S: 79 hp-liter / 5200 RPM / 6500 RPM / 6240 liters-minute at 5200 RPM
2.7 RS: 77 hp-liter / 5100 RPM / 6300 RPM / 6885 liters-minute at 5100 RPM or 10% more air into a 12.5% larger engine.
3.0 RS: 76 hp-liter / 5000 RPM / 6000 RPM / 7500 liters-minute at 5000 RPM or 8.9% more air into an 11% larger motor then a 2.7.

Why? Because near as I can tell they were all running the same induction system. So even though the 3.0 was larger and reportedly had larger valves, you can only pull so much air through the induction system. Once you hit the torque peak the amount of air per cycle pulled into each cylinder actually starts to drop because of increased friction in the induction system. This is why the torque drops and the only reason that the HP continues to go up is because the engine speed increases faster then the resistance does for a while.

Anyhow, as the S cammed engines based on the 2.4 MFI system got bigger, they reached the point of diminishing returns at lower and lower revs. Once you've reached the peak airflow, more fuel per cycle doesn't get you anything but a rich mixture. I propose that this is why the 3.0RS didn't blow up from being too lean. Because the MFI pump was fully capable of pumping the fuel needed, but the intake stacks, throttle bodies and ports were the limiting factor. Basically the amount of air consumed by an engine is an excellent predictor of the HP that it can generate.

PS: Warren pointed out on another thread that Porsche only got a measley 6 extra HP out of the 3.0RS when they used 8.5:1 pistons like in 2.7RS. When they bumped the CR up to 9.8:1 they were able to get another 12 because the extra CR propped up the dynamic CR at peak engine speeds when the induction system was choking off additional flow. It's at those peak engine speeds when the peak HP numbers are generated.

There seems to be a misunderstanding.
The 3.0 I was referring to was a racing engine 280 hp and it ran well (It ran 1:28 @ Willow in 1996) on a 2.0 E MFI Pump with only minor tweaking. No internal modifications !!!
Cosworth pistons 10.5 to 1
Twin plug
RSR sprint cams
43 mm ports ( I know, too big)
1 & 7/8 headers
44 mm butterflies
Custom built stacks ( see picture)

I would not build this engine today but back them we didn't know any better.


http://forums.pelicanparts.com/uploa...1086879618.jpg

Henry, I think we all understand. What we're trying to figure out is how a 2.0 pump adjusted in the normal fashion can support a well running 3.0. The discussion is important to a couple of us - one with a 2.4E pump going to 2.7S, the other with a 2.4S pump and a 2.8S engine. Do we, or do we not, budget $1400 for someone to re-cam and calibrate our pumps??

Inquirying minds need to know!

I think that statement is pretty optimist.


Anyway, what I'm saying is install your pump it's not that much work and try it.
If after simple adjustment (simple being the operative word) you find it unbearable then figure out what it needs ( too rich at idle, lean at mid range, etc.) and have a pump built to suit.

That's how we did it. There are some not so simple adjustments that we did that had to do with linkage and leverage changes but those changes are made on a by car basis.

You guys might work together.
The guy with the 24S pump could trade with the guy with the 24E pump. The 24S pump will work fine on the 2.7 RS engine. For the 2.8 if this is a high performance engine no stock pump will work perfectly. Everything will be a compromise.

I fact I may have just the pump you need in stock. I have a 2.4 pump with a 2.7RS (060) space cam in it set up for high performance 2.8.
We are also working on a governor that is customer friendly.
Prototypes will be on club cars soon.
Call and we'll talk.

Pumps on the shelf.
Things to come.http://forums.pelicanparts.com/uploa...1086901478.jpg http://forums.pelicanparts.com/uploa...1086901514.jpg http://forums.pelicanparts.com/uploa...1086901537.jpg

Well this is definitely getting bookmarked in my MFI folder :)

Would a 2.4 T or E pump be usable on a 2.7 RS type engine? I'm assuming the space cam would need to be changed?

Some good discussion here.

I have a 2.7RS motor and Gus built the pump for it. It has the 2.4S space cam, and when i inquired to Gus (about 2.5 years ago), he said the 2.4S cam "should work fine".

All I can tell you is the car runs great (when together), and there doesn't appear to be any problems with leanness. Now, what I do wonder, is what would it be like with the RS cam? Any different? Who knows? I didn't want to spend $500 (or $1,400 for that matter), and get no noticeable performance or combustion improvement.

I would love to find someone who has an RS pump, and throw it on and see what happens.


JA

Sounds like you'd need an engine dyno to get a meaningful comparison.

Another question: what role does compression ratio play in this? Does a higher CR require more fuel? AFR is AFR, regardless of CR, yes?