RSR clones with RSR clone engines?

[pieterk]

This morning I was re-reading some of the RSR threads here and got to thinking about all the different paths that people take towards hot-rodding their RSR inspired cars, and the 3.2s and 3.6s seem really popular. As far as I know--not having driven any--they make safe, reliable, good power while keeping the cars within a comfortable street tune, etc.

I'm curious how many people are running more aggressively tuned 2.8s to 3.0s above 2.7 RS spec (i.e., in excess of ~78bhp per liter) in track/street cars that are smog restrictions exempt. What kind of power are you reliably producing, what's your compression ratio, induction, exhaust, cams, valve work, safe redline, engine life, etc.?

Of even greater interest, those of you whose engines have exceeded the 100bhp per liter mark. Anyone running engines like this in their track/street cars? In other words, anyone running an engine in their RSR clone that is more or less within spec of an original RSR? I know there are quite a few RS correct engines in RS clones, but what about 73 2.8 RSR or 74 3.0 RSR correct engines in RSR clones?

Recognizing that this would probably end up being more expensive and less reliable than just doing the 3.6 swap, how feasible would it be to start with a good stock 3.0 core and using newly available P/Cs, induction, etc, build an engine that meets those specs? Could be fun! Reliability would matter, but obviously there'd be a lowering of that threshold...and it would be almost exclusively a track car--but have to remain street legal, if only to get it to and from the track!

This summary on the development of the 110 bhp/liter 2.8 RSR helped pique my interest:

http://www.ultimatecarpage.com/frame.php?file=car.php&carnum=1681

Also, according to that summary, could the .1 liter bump in displacement and the bump up in CR to 10.5:1 really yield that much more power? I find that hard to believe. Seems there would have been a lot more work done to the engine.

pieter

[pjv911]

I have 240 rwhp from a 2.6 RSR(kinda) spec engine . Here`s the specs .

1967 911s crank with original uncut soft nitrited finish 66mm
1967 911 s nitrated rods
1967 911s type 901/02 aluminum case which has been extensively modified inside including the mfi pump mount tig welded on the outside, as well as the distributor base mount.
92mm oem mahle 2.8 RSR pistons
1974 2.7 heads modified for twin plug and mfi injectors. Heads are mildly ported (37mm/36mm) and are otherwise stock with the standard 46/40 valves. Springs are not stock but didnt get the brand.
Camshafts are factory S grind
Oil pump is a factory carrera unit
Chain tensioners are 930 units with clamp on bottoming locks
Distributor is an SC unit modified with Andial`s kit for twin plug and using marrelli cap and rotor . Using twin factory bosche CDI units and standard bosch cdi coils.
Injection consists of 2.2 S magnesium stacks opened up and mated to factory R/S carrera throttle bodys (same as 2.4 S aside from the idle circuit).
MFI pump is a authentic 2.7 R/S unit (019) which was rebuilt by gus at pacific . Stacks and throttle bodies were done by eurometrix.
Exhaust is 42mm RSR headers with a dual in dual out stainless GHL muffler (unbelieveable sound)

The power from the engine is unreal . Low end torque is plentiful and once your past 5500 rpm its like a turbo kicks in .
Compression should be right around 10.5:1 . There are copper base gaskets under the jugs which raise the deck height (lowering CR) . In short I would not trade this engines power for a 3.6 . Nothing has an exhaust note like this motor . I try to shift it around 7000 rpm but it pulls all the way to 8k(done it 2 or 3 times) . Im just a little shy I guess . I dont want to hurt it . Gas mileage seems great (not enough miles yet to know). Driveabilty is just as easy as the stock 2.7 I was prevoiusly using .

The car is a 69t coupe mounted to a close ratio factory S 901 box with an open diff.
Car weights under 2300lbs .

Kurt Williams

[jacko241]

The engine in my race car is somewhat based on the 3.0 RSR. It is a 3.0 SC twin plug with Electomotive crank fired ignition, 10.2 compression, RSR sprint cams, Carrillo rods, heads are mildly ported to approximately 40mm, 49mm intake valves, with race springs and retainers. I am running 46mm Webers, with short PMO manifolds. Exhaust is handled by 1 5/8 headers with Phase 9 mufflers. Power is around 265 hp (at the crank) at 6100 rpm and we ran it all season reliably to 7500 rpm with 36mm venturis. We are changing to tall PMO manifolds and 42mm venturis (with the very capable help of Rennsport System's Steve Weiner) which should move power peak up in range and improve hp to right near 300. According to engine builder, engine should be good for 30-40 hours of track time before freshening.

[Bryan Beaumont]

Kurt,
The spec list and description of your engine gives me tingles...I agree with you about the sound and feel of an engine such as yours. They tend to snarl and growl at you, and sound B!tchin. I'm sure you will have many miles of smiles ahead with that car. Pretty hard to beat, IMO.

[jacko241]

240 rwhp equates to over 280 crankshaft hp by my calculations, which from a 2.6 litre is very stout in my opinion. Congrats!

[Elombard]

Kurt

What would that motor cost to build roughly if a guy had the 2.7 heads and the early motor already. In other words how much would the machine work, ignition, and injection cost if you sourced some of the parts used?

Sounds awesome!

[pjv911]

I bought the engine preassembled from Al Bass in Ottawa Canada . He built it for a customer to be used for racing . The customer was not saticfied with the engines output and had him build a 3.5 in simalar fashion immediately after . I was in the market for an engine upgrade at the time and it dropped in my lap for under $10k . I was very lucky to score . I guess some people can afford to not be saticfied with 240hp . From what I understand the 3.5 engine make well over 300hp .
I would figure if you had nothing to start with my 2.6 engine would cost nearly $20k to duplicate . If I was starting from scratch I too would choose a short stroke 3.5 but ....
BTW I have never opened or inspected any internal part of the engine . It was a bolt in and go . And man does it go .
As for 240hp it was actually 237hp on my own dyno (see the back page of waynes engine book, thats mine). I was using race fuel with the timing at 26 deg total . For normal driving I use a mix with 93 oct/116 oct and run the timing at 24deg . My lowest hp peak in regular driving mode was 216 rwhp . And a best of about 225 rwhp. Temp, humidity, consecutive runs, etc , play a large roll which determines a relatively inaccurate result anyway.
One thing I am positive of is that its making almost 100hp more than the previous 2.7 I pulled out . That one peaked at 156rwhp and was a fresh engine .
Am I happy with it ...... OH YEA.

Kurt Williams

[Elombard]

Very Nice I would like to do something similar but with carbs and an elctromotive twin plug set up to save some cash. I need to put together some money and wait for the right deal on an already built motor like you did.

[ajserrano]

Trying to build a very accurate 3.0 liter RSR factory engine and here is where I'm now at with this project...

http://www.pbase.com/slidevalve911rsr/myrsr_30ltr

Also building a 2.8 liter RSR factory engine and already have a significant number of the parts I need;

http://www.pbase.com/slidevalve911rsr/myrsr_28ltr

...but I don't yet have a "factory RSR chassis" and hope to one day find one.

Once the engines are built, I'll post the dyno results on this thread...

Armando
http://www.pbase.com/slidevalve911rsr/root

[tom1394racing]

Here's a link to the dyno results for the 3.0 that I built for my RSR clone.

Another RSR Clone Project - Dyno Day

It gives about 280 HP at the rear wheels on pump gas. No doubt that this is a more expensive option than dropping in a 3.6. I wanted to have some semblance of an early motor in look and feel.

The throttle response in this engine is unreal. It feels like a sport bike when I stomp on the throttle at anything above 4,000 rpm. From 5500 to 7500 rpm, the acceleration actually increases and you can feel the engine really wind out as the cams come into their own. The sound is also great with caps on or off the ralley silencer. The big surprise for me was the tractability of the motor for around town street driving. It's easy to drive and pulls well from 1,000 rpm. It also idles and starts well.

In short, I love this motor and wouldn't trade it for a 3.6.

[pieterk]

All very inspirational!

I'm glad to see that some people are pursuing this.

Armando, your project is admirable--and it looks crazy expensive. Beautiful details on all the photos; thanks for that.

Kurt and Tom, your engines are closer to what I'm thinking of; not so much a period and part correct RSR engine, but something approaching those specs with whatever modern parts will get you there.

Tom, thanks for the link to your other thread. Very informative. Aside from the hp/tq consideration, the increased throttle response is really enticing; it sounds superb!

I wonder how much more you could get out of it if you tuned for 100 octane too.

Anyone else?

[Jack Olsen]

Actually, I'd guess that most of the RSR clones out there have less than 3.2 liters of displacement. If you're going to go to the trouble of reproducing the 2.8 RSR or 3.0 RSR look, you probably want the feel and sound of a more high-strung motor to complete the package.

For the rest of us, a 3.2 or 3.6 is probably chosen because of budget limitations and/or our intended use for the car. If you want a daily driver, a DME motor is going to offer great reliability. And if you also want to track the car, the bang-for-the-buck of a larger-displacement motor is tough to beat. My 243 rwhp motor cost me $5,000, out the door (and I was able to sell the old 2.2 on top of that). Not including street driving, I have somewhere in the neighborhood of 300 track hours on it now. All it's needed so far is oil. If I had gone with a built-up 2.8 instead, my engine budget would have had to start pretty big, and then expand to absorb those 30-40 hour maintenance rebuilds.

Don't get me wrong -- I still drool when I see the simpler, more-period-correct race engines at R Gruppe meets. But each of us has got to find the best solution for our particular use and budget.

[ajserrano]

Hello Jack, it will be great to have a photo gallery of your 911 RSR project at my RSR site.

If you say is "OK", please email me some photos. ajserrano@msn.com

It would be created here http://www.pbase.com/slidevalve911rsr/911rsr_project_cars

Thank you for your consideration...

[pieterk]

Originally posted by Jack Olsen
For the rest of us, a 3.2 or 3.6 is probably chosen because of budget limitations and/or our intended use for the car. If you want a daily driver, a DME motor is going to offer great reliability.

Absolutely. The 3.2 or 3.6 upgrade makes an enormous amount of sense on all fronts. And in the long term, it's most likely the direction I'd pursue--once I get the car to begin with. I just love the idea of engines like the RSR spec ones. But I need to get the car first and learn it as it is.

That said, the car I'm looking for will be a track car first, a street car second, and never a daily driver, so I suppose as long as my income doesn't dry up, I'd be willing to accept a modest increase in reliability risk.

My 243 rwhp motor cost me $5,000, out the door (and I was able to sell the old 2.2 on top of that).

Wow! From what I understand, that's an incredible deal. With pricing like that, it's a given. I wouldn't have hesitated for a second.

[tom1394racing]

For a point of reference....

My 3.0 RSR spec motor with PMO's cost in the neighborhood of $20k (ouch it hurts to admit it) and I built it myself.

[pjv911]

Originally posted by tom1394racing
For a point of reference....

My 3.0 RSR spec motor with PMO's cost in the neighborhood of $20k (ouch it hurts to admit it) and I built it myself.

Exactly . You could add another $10k-$12k to your $20k if you were paying labor + additional markup on parts.

Kurt Williams