Value 2.7 RS engine

[botic21]

Hello everybody,
I would like to know where can I find the serial number on a 2.7 RS engine?
Also, do you know the price of this kind of engine?

[Bobboloo]

The serial number will be on the support for the fan on the side opposite the distributor.
The number would be between 6630001 and 6631549.

The value would be determined by the condition of the motor. Does it have the MFI? etc.

It is a rare motor so even in bad condition it will bring money. How much depends on the buyers.

Bobby

[Wayne 962]

The case is probably the only thing worth anything on the engine, as it will have the golden serial number. Everything else is readily available. The cams are 'S' cams, the pump is a 2.7-RS spec (which can be converted), the stacks are the same as the 2.4, the pistons and cylinders are still available. I believe the heads are regular 2.7 heads (not completely sure), and the internals are plain vanilla 2.7 stuff.

That's why it's easy to do a 2.7RS conversion...

Speaking of which, the factory RS spec is not a great performance engine. It's too low compression (8.5:1). If you're doing an RS spec, you might as well add twin plug and a set of high-compression pistons. This is a great way to improve upon the RS spec. No need to recal the pump with the bump in compression and the twin plug either. This would make a killer engine...
(this is also detailed in the new book)...

-Wayne

[cegerer]

"...the factory RS spec is not a great performance engine."

Yeah well, other than the fact it is the heart of the best performing street 911 in history by nearly all accounts - all while running on low-octane 87 unleaded fuel! But I suppose anything can be improved upon. -- Curt

[botic21]

I'm waiting for some news coming from the guy who is selling it...

Nobody has an idea of the value of this engine?

Olivier

[gregk1]

Well I just bought a 2.7 rs spec motor from a guy in oakland. With rs spec P&C, polished and shot peend rods, racewere bolts, S cams, stainless Valves, ported heads, 964 oil pump, 7R case, Less carbs, built buy Otto's in Venice CAL. I and Otto as well Think I Stole It for $1800

[TRE Cup]

depending on condition and mileage, we have seen real RS motors going for $5k to 12k. That is for ones with the correct serial number and other oe equipment
RE: Wayne's comment on the RS heads being the same as any 2.7 head. ONLY if those 2.7 heads are for mechanical injection!

[Randy W]

I have to agree with Curt, IMO the 2.7RS spec engine with MFI qualifies for "great performance engine" even with it's low compression ratio. It's hp/liter is among the very best, and one drive in a good one will convince most people of that. There are some variations in these engines, so you may be fooled into thinking it's not anything special if you drive a so-so one. No doubt 9.5:1 would "wake it up, but most people that have these engines in their 911 are not in a big rush to change them.

[Early_S_Man]

The RS 2.7 heads are the SAME PART as 2.2/2.4 'S' heads ...

The 'magic' of the RS 2.7 and RSR 2.8 engines surprised the factory engineers when it came time to go to 3.0 liters ... efficiency fell off ... as did the hp numbers on the dyno! To get the same additional 20 hp from the street RS 3.0 going up to 3.0 ... the compression ratio had to be raised to the max 'streetable' 9.8:1 from the lazy 8.5:1 of the 2.4 and 2.7 'S' engines! Additionally, the IROC-spec RSR 3.0 engines with regular throttle-valves ONLY GAINED AN ADDITIONAL 7 hp over the RSR 2.8 engine! It took slide-valve induction AND 'SPRINT' CAMS to get the power back to the 'normal' 110 hp/liter output level of the smaller racing engines! Development of the 3.0 took much longer than normal!

Clearly, at the 3.0 liter displacement ... the valve and port sizes were no longer optimum for either street or racing engines! It should not be too much of a surprise why we never saw a 6.0 liter 917 flat-twelve engine, even though it would have been within easy reach!!!

[skinnerd]

I agree with those saying that the 8.5:1 RS engine is still a killer engine. You'd pay easily up to $12K for a rebuilt "serial numbered" RS motor. My exact replica based on a 2.4E motor basically cost me about the same. They'll run on any kind of fuel (yes 87 octane), and still haul.... how is a 13.7 in the quarter mile? Mine was getting 208hp at the rear wheels on a rolling dyno. This engine will hold it's own with almost anything. The sound of the MFI induction on take off is incredible. And they are basically bulletproof. What's not to like?

[Wayne 962]

Hmmm, some clarification is in order. Yes, Warren is 100% correct there, as the 2.2/2.4/2.7 heads are almost exactly the same. I believe the only differences between the years are a bigger cut for the cylinder lands, and the MFI injector plug. What I was referring to was that they weren't necessarily special, or difficult to find.

Secondly, I suppose that I should clarify my remarks a bit:

I said:

"Speaking of which, the factory RS spec is not a great performance engine. "

In hindsight, that statement sounds a little harsh. Let's rephrase it and say that the 2.7L RS engine is a good performance engine, but not a great performance engine. I love this engine, but the factory RS-spec that everyone builds to can so easily be improved upon at rebuild time.

The problem is that everyone builds their engine to 2.7RS specs, when for just a little more, you can improve upon it, and make it a great performance engine. Number one thing to do is to use JE pistons and custom-dial in the compression to about 10:1. Then, if you want, you can go higher, but you will need twin-plug ignition. You can also run the 2.8 P&Cs too, although this will probably require a recal of the pump.

Oh, all of this assumes that you've had ALL of the proper work done to your 2.7L case already...

-Wayne

[Early_S_Man]

Wayne,

The EXACT SAME 2.2 'S' MFI head ... 911.104.008.00 (assembled, ready to install) or 911.104.038.00 (bare without valves, with studs) was used as mfr first in the fall of 1969, no changes ... in the 2.4 'S' and RS 2.7 engines, per the '72-'73 parts catalog!

I have a new spare 2.4 head, and Nikasil RS 2.7 p & c sitting on my desk ... mated perfectly, no problem with the spigot/recess on the 2.4 head!

[CamB]

I have been doing a lot of thinking on the efficiency/port size thing (please excuse and incorrect terminology or lack of engineering knowledge to follow).

The specs I have for MFI and S cammed engine are:

1991cc 170hp, 9.9:1 c/r = 85.4hp/litre
2195cc 180hp, 9.8:1 c/r = 82.0hp/l
2341cc 190hp, 8.5:1 c/r = 81.2hp/l (not certain on c/r)
2687cc 210hp, 8.5:1 c/r = 78.2hp/l (note to Warren - my opinion is that this is where it dropped off - the problem is just worse on the 3.0)
2994cc 230hp, 9.8:1 c/r = 76.8hp/l

This leads to three questions:

1. All other things being equal, an increase in capacity should lead to an increase in power - however, looking at the above, this is not necessarily the case. So, what sort of power would S cams make in a 98mm P&C short stroke 3.2. Assume ported heads and enlarged throttle bodies commensurate with the increase in capacity.

2. What power increase does twin plug and higher compression offer - is it simply a case of higher compression offering more power and twin plug being required to use higher compression??

3. What is the relationship between compression increase and horsepower increase (eg 1 c/r point = how much hp).

It's a wonderful motor to drive! For a street car the motor is perfect. I almost separated mine from my 72S because I needed the money but I'm glad I did not. I was driving my daughter to school today and the car is just a blast with that motor back there. No one seems to want to pay what I want for the car so I'll keep enjoying the drive in the meantime.

My website below shows pics of what the id numbers look like.

[CamB]

A second thing - a real RS engine could be worth quite a bit for someone with a real RS. Other than that, condition is key.

And my experience is that twin-plug isn't THAT cheap.

[Wayne 962]

CamB - you're right, twin plug isn't cheap. Raising the CR to about 10:1 or so is.

Off the top of my head answers to your questions:

1- I don't have an exact power number for this engine, but it is a recommended combination that does work very well as a performance engine. Definitely well over 200 HP, and not very peaky

2- Yes, twin plug doesn't add HP by itself, but instead allows you to run higher compression.

3- There is no simple answer. It depends upon the displacement and the cams that you are running. A good way to learn about this is to look at T,E,S combinations and see the HP differences between them. They basically changed the cams, and the compression ratio (through the use of higher CR pistons) to achieve more HP (with other changes to match these two)

-Wayne

[CamB]

Ooops, to clarify, I'm talking about an SC with 98mm P&C to make 3.2 litres. Imagine the 3.0RS engine but with 98mm and 10.5:1 (and twin plug and blah blah blah).

My guess is about 255-275hp (there are other factors for the last 10hp, but my guess for MFI would be 255-265).

[DavidPorter]

So, Warren et al, are you saying that no head machining is required to use 2.7RS P&C on a 2.4 engine? So there was enough room for the bigger bore at the head but not at the case?

[Early_S_Man]

David ... that is exactly what I am saying! But, the factory parts catalogs said it first, and a long time ago ... to those that pay attention to such matters!