3.6 cams in 3L

6771911esses · 11-10-2005, 04:24 PM

Anyone run any 3.6 spec cams in a 3L. I have been told that this is a wicked set up? What degree set up should be used in this case?

Jeff Alton · 11-10-2005, 04:33 PM

PLenty of info on this between this forum and the technical forum. I have used them a few times in rebuilds. Wicked, that is a stretch, but they are a nice upgrade to do while the engine is apart. I have set them everywhere from 1.25mm-1.4mm.

Cheers

6771911esses · 11-10-2005, 05:08 PM

I was told that these cams with a 2.7RS MFi on a 3L could make 385hp. Exact comp. ratio was not specified, nor could the person tell me more specifics on the engine. He saw it race at Zolder (Belgium) and said it blew everything away.

BURN-BROS · 11-10-2005, 05:17 PM

That reminds of the "I caught a fish this big story". Making over 110 HP per liter is a tough sell. To do it with 964 cams is impossible. Maybe this was a mild turbo car. Then it all makes sense..

6771911esses · 11-10-2005, 05:37 PM

A Euro 3L makes 208 hp, add some compression, wilder cams, and RS MFI set up and you should get in the area of 285. Maybe that is what he meant. Give or take 100hp.

Basically, I am going to build a stroked 3.2L with a 3L engine, run a 2.7RS (019 pump) and butterflies (port matched)/ stacks, single or twin plug (TBD). This guy I spoke to in Europe suggested 3.6 cams, others in the US suggested having S spec cams made for the 3L.

Would like to get some more feed back.

Noah, some small displacement engines, i.e 2.8 produce close to 300 or 330 hp with MFI or Webers (46). See all the vintage RSRs and replicas. It's all about the combo of parts. I don't doubt that a 3L can make more hp than a 3.6. 385 maybe very exagerrated, he may have meant 285. I will check with him again.

Jeff Alton · 11-10-2005, 05:51 PM

The 964 cam is FAR from wild, infact as far as cams go they are MILD. They are and upgade to the factory SC/Carrera cam but have very limited overlap and a wide lobe center to work with the common TB intake and to help make them run clean for emmissions. They certainly are an upgrade though, you are putting a cam built for a 3.6 liter motor into a 3.0 motor and you will feel it. It makes a nice strong motor no doubt, but wild they are not.

I run them in my current 3.2 but will be using something bigger in my 3.4 as they are too mild for that motor IMO.

Cheers

camgrinder · 11-10-2005, 10:44 PM

Maybe the guy was thinking about 3.8 RSR type cams?

6771911esses · 11-11-2005, 02:52 AM

Camgrinder, I sent you a pm.

cstreit · cstreit's Garage

What these guys are saying is true...

The 3.0L just ins't going to make that kind of horespower unless you turn it into a VERY different motor. Consider this, the 2.0L motors that I have built that make comparable horsepower per liter have lifespans in the 30-45 hour range...

The 3.6L cam is a good cam for a stock 3.0L motor BECAUSE it is so mild. For two reasons:

1. Intake design. The stock air metering device in the 3.0L cannot take the intake reversion caused by a hotter cam, one with a lot of overlap in exhaust/intake. It flutters the plate causing fuel delivery issues.

2. Piston design: THe pistons were designed with a high "center offset" dome shape to help remix and squish the fuel properly based on the intake limitations. These pistons will not allow a lot of cam lift because the clearance just isn't there.

In order to approach even 300 BHP in a 3.0L engine you must start replacing a lot of bits from the pistons and cylinders on up. As a comparison my 3.0L sports Mahle RSR pistons and cylinders, 10.2:1 compression ratio, twin plug ignition, flowed heads, lighter valve train and upgraded components to spin to 8000RPM (briefly), much hotter cams that what you are talking about, and weber 46mm carbs and I'm in the area of 265 HP at the crank.

Could you get 385 HP out of a fairly stock 3.0L? No Way! Can you get 300HP out of one? Yes, but probably at a cost of $25,000 worth of modifications or a pretty big turbo/supercharger and greatly reduced engine life.

camgrinder · 11-11-2005, 07:15 AM

Quote:

He saw it race at Zolder (Belgium) and said it blew everything away.

Just curious, any other details on this car? who owns it etc.

kenikh · 11-11-2005, 10:14 AM

From the research I have done, if you want 100HP/L in a 3.0, you'll have to run, at a minimum, DC40 cams (RSR sprint cams are porbably better) and high compression (10+:1) w/ twin plugs and have a valve train that support some SERIOUS revs.

jluetjen · jluetjen's Garage

If you want 100 HP/L in any sized 911 motor, you're going to be talking about 906, DC80's or RSR type cams. You'll need to plan on a rev range from 5000 - 8000 RPM, and have the rest of the motor (porting, bottom end, etc) built to support that kind of airflow and rev's.

I doubt that there's any other way to get there without turbocharging.

KobaltBlau · 11-11-2005, 12:30 PM

Agreed with John. GE/DC80s not 40s.

cstreit · cstreit's Garage

Even that gets you to 300 only...

KobaltBlau · 11-11-2005, 01:17 PM

Right. 100hp/l ain't peanuts!

6771911esses · 11-11-2005, 07:27 PM

Gents, I beg to differ.

Walter Rorhl drives an ST with over 330hp, RSR are under 3L and make anywhere from 308-315 hp. These all run MFIs just like the motor this guy described to me. He was probably wrong specifying 385 hp, but I don't think that he could be wrong if he meant 285 hp.

The engine I have in mind to build will be a short stroke 3.2L (Max Moritz pistons), 3L case, 019 MFI pump and RS stacks/ TBs. I have most of these bits and pieces except for the "hotter" cams and ignition set up. I am obviously dumping the CIS system and pistons. I may have to get the RS pump recalibrated by Gus Pfister for the 3.2. I don't think this will be a cookie cutter formula engine. Some experimentation will be required.

I continue to sollicit feedback from experts.

MN

KobaltBlau · 11-11-2005, 10:23 PM

I think he is still wrong with 285 if he is saying std 964 cams and a 3.0. You did not answer camgrinder's very smart question regarding 3.8 RSR type cams.

the early RSR/ST engines you describe have very different cams from a standard 3.6.

camgrinder · 11-11-2005, 10:43 PM

Ok... its a guess. But I bet the car is Red and has the number 256 on the side?

6771911esses · 11-12-2005, 04:00 AM

John,
I completed your inquiry form.

To all others: I would love to get 250-260-ish HP with mucho torque, quick throttle response and MFI sound effects. I like the "vintage" configuration with MFI for an "RS" replica. I could stick a 3L cis or 3.2 in it but that doesn't appeal to me. I purchased most of these bits from a fellow PP-lister that started out with this project. He has given me a configuration that should work, but I would like more ideas before finalizing this chapter.

MN

'67 S
'70 2.2S MFI
'71 RS Replica (911/83 MFI and prepped 2.4E MFI)
'67 911 (future "R" replica)

jluetjen · jluetjen's Garage

Quote:

Originally posted by 6771911esses
Gents, I beg to differ.

Walter Rorhl drives an ST with over 330hp, RSR are under 3L and make anywhere from 308-315 hp. These all run MFIs just like the motor this guy described to me. He was probably wrong specifying 385 hp, but I don't think that he could be wrong if he meant 285 hp.

Letse, the 2.8 RSR makes 308-315, so the smaller 2.5 ST motor (which shares much of the same configuration with the RSR, except it has a smaller capacity) makes 330? Something doesn't add up.

Quote:

The engine I have in mind to build will be a short stroke 3.2L (Max Moritz pistons), 3L case, 019 MFI pump and RS stacks/ TBs. I have most of these bits and pieces except for the "hotter" cams and ignition set up. I am obviously dumping the CIS system and pistons. I may have to get the RS pump recalibrated by Gus Pfister for the 3.2. I don't think this will be a cookie cutter formula engine. Some experimentation will be required.

That sounds kind of like the 911 SC/RS rally engine which made about 255 HP at 7000 RPM. It's not clear what sort of cam they used in that engine, but given the 7000 RPM peak HP engine speed I'm thinking that it was something less then an RSR cam which normally would peak up around 7800 RPM. Assuming that you increase the airflow through the heads accordingly, your 3.2 would be putting out about 272 HP in similar trim. Certainly not a bad engine to play around with on the track, but still a far cry from 300 HP+.

Can I "call the question". What is it you're looking for in regards to input?

Quote:

I continue to sollicit feedback from experts.

I don't know if I qualify as such, so you're welcome to take my response for a grain of salt. Noah has built a 3.0 with a 964 cam, Chris builds and races a 3 liter 911 and Camgrinder (as his nickname implies) grinds cams for a living. Do you have an alternataive definition in mind for the term "expert"?