3.0 SC HP Expectation - post modification

[Jeff Higgins]

Hmm... I really don't know, PFM. I'll defer to the real experts here, like Steve or Henry. I've been told, and have read in several references, that they are good to at least the mid 7,000's, if not a bit higher. I don't think you need Carrilos or Pauters until you are pushing 8,000-ish, but I could be wrong about that. I don't plan on testing it in my motor, and I don't have the experience with the number of motors under my belt that some of these guys have. Maybe one of them will see this and chime in.

[kenikh]

SC rods aren't great, but they are better than 3.2 rods and will be fine for 7K. Just make sure you use ARP bolts.

[PFM]

I would like for the motor / cam combo to turn 7500 if the dyno says it makes power there. I am looking at a 3L RSR dyno sheet with PK power at 7800 RPM. I believe that motor had Carillo rods installed.

Any input on Raceware rod bolts? The pistons and pins are light weight.

Just looking for input not a guarantee.

PFM

[Steve@Rennsport]

PFM,

If you are going to run 7500 RPM, you need better rods than OEM ones.

IMHO, ARP bolts are better than Raceware ones.

Proper rods come with premium bolts; ARP or SPS ones.

You also need some extensive oiling modifications at those RPM's if you expect the engine to live.

[D911SC]

Steve,

With my planned combo of 98mm 10.5:1, PMO 46mm, twin spark (looks like it's headed this way), DC60 cams do I need to look at new rods or just better rod bolts such as ARP?

Do I need oiling mods as well?

Thanks,
Darren.

[kenikh]

If looking for 7500+ RPM, you will be well advised to get rods, cross drill your crank, drill the center main and groove your center bearing. In this case I REALLY like R&R GT3 spec rods. FWIW, Steve did the case and bearings for my motor which was designed for over 8K operation. He likes Pauter rods, which he can also provide.

It's worth the peace of mind, even if you might get away without them, to KNOW you did it right and never worry.

[lindy 911]

I agree that if you were building a race motor that the rods are subject. Also the oiling would need to be addressed if you were going to run 7,000+ for any length of time like racing. But we are talking about a street motor here and honestly 7,000 RPM is going to be every now and then at the most. Seven grand in second gear is already ticket territory!

My motor runs very well between 2,200 and 7,000 with an obvious increase at 4,000. From 4,000 to 7,000 it'll run with just about anything on the street. This is all I was looking for and I think D911SC would be very happy with this set-up. There is a point in the build process that you have to say enough is enough.

Don't get me wrong, I would personally love to have Pauter rods, a Henry Schmidt crank, shuffle pinned case, turbo oil pump, etc, etc, etc, etc. The list goes on forever. But this is a street motor with a builder on a budget.

Lindy

[kenikh]

Originally Posted by lindy 911

Don't get me wrong, I would personally love to have Pauter rods, a Henry Schmidt crank, shuffle pinned case, turbo oil pump, etc, etc, etc, etc. The list goes on forever. But this is a street motor with a builder on a budget.

I had the same conflict for my spirites street motor. In the end, it has taken me 4 years to assemble the parts for my motor because:

Originally Posted by kenikh

It's worth the peace of mind, even if you might get away without them, to KNOW you did it right and never worry.

It really gets no simpler than the above...you can't have it both ways. Rev limit to 7K on stick rods and ARP bolts or nut up...otherwise, you are rolling dice.

Originally Posted by lindy 911

I agree that if you were building a race motor that the rods are subject. Also the oiling would need to be addressed if you were going to run 7,000+ for any length of time like racing. But we are talking about a street motor here and honestly 7,000 RPM is going to be every now and then at the most. Seven grand in second gear is already ticket territory!

You will engage in all of the above...trust me!

[lindy 911]

I hear you.

I guess, for me at least, half the fun of these builds is the build itself and future upgrades to the original build. Unlike the guy who builds a stocker and doesn't want to touch it again for 150,000 miles, the prospect of pulling the motor next winter to add new bits and pieces so you can add another 500 rpm to the rev limit chip is exciting. Maybe I'm coming from a different perspective here but I enjoy having the motor on the stand when the weather is not cooperating. It also makes me a better wrench regarding the 911 motor and as they say "practice makes perfect".

In my case, 7,000 rpm is the upper limit of my power band so I'm not concerned right now with my rods. I do plan to improve the heads which will raise the limit and at that time I'll weigh the other upgrades needed. Like I said; rods, crank and case mods, pump and other goodies are on my wish list and will someday find a home in my 3.0.

Lindy

[D911SC]

This is great input and really helps me out in planning the upgrade.

Given that this is a street car I do want to put a limit on how far I go. I am chasing a fast motor but it won't be raced, maybe a short stint on club track days at best. I doubt I will be pulling this down for further mods as there is plenty to spend on other parts of the car. So far this seems to be the current spec

1. 3.2SS using JE 98mm 10.5:1
2. DC60 cams
3. PMO's 46mm
4. SSI
5. Dansk 2 in 2 out
6. ARP or Raceware bolts on stock rods
7. Twin spark (insurance against detonation)
8. MSD Ignition
9. Rev limited to 7000rpm (more insurance!)
10. Ported heads (assuming this needs to be done as I believe I have smaller port SC heads)

Anything else I need to allow for in the rebuild?

[kenikh]

I agree with you except for the cam. Without big revs and port work, DC60s are a poor choice. You'd be better served with DC40s, DC44-102s or DC-GT2-102s. All will benefit from bigger ports, but don't need them, whereas the DC60s do. On a bigger motor, these make mad power and torque to 7000 RPM. The DC44-102s will make the most power and have the most headroom, but will require race springs. The DC40s and DC-GT2s can use stock springs. All can use stock retainers at these revs.

[D911SC]

Originally Posted by kenikh

I agree with you except for the cam. Without big revs and port work, DC60s are a poor choice. You'd be better served with DC40s, DC44-102s or DC-GT2-102s. All will benefit from bigger ports, but don't need them, whereas the DC60s do. On a bigger motor, these make mad power and torque to 7000 RPM. The DC44-102s will make the most power and have the most headroom, but will require race springs. The DC40s and DC-GT2s can use stock springs. All can use stock retainers at these revs.

Thanks for the input kenikh. I suspected the DC60's were borderline but I have read plenty here about guys using them with similar configurations. I felt that these were still a good option for what I wanted to achieve.

What sort of power can I expect from DC40's? Where does the power come in as compared to DC60's?

Darren

[lindy 911]

What year is your SC? If it's a 78 or 79 it has the big port heads. Mine is a 78 which may be why the GE60 cams work so well in my build. There is always a better combination, no matter what you end up with. Someone will always be able to improve on what you have done. The big question is will the combination you have above satisfy your build requirements?

IMO, being that it's a 3.2 and then basically the same thing as what I just built, your motor will be fast and reliable. Not to say it will be optimal or perfect, but fast and reliable. That's what I have and it puts a very large grin on my face every time I fire it up.

Lindy

[kenikh]

Originally Posted by D911SC

Thanks for the input kenikh. I suspected the DC60's were borderline but I have read plenty here about guys using them with similar configurations. I felt that these were still a good option for what I wanted to achieve.

What sort of power can I expect from DC40's? Where does the power come in as compared to DC60's?

Darren

They will "work", but you would be leaving power on the table since you can't run them in manner they were designed. You can look up DC40 (also called GE40 and Mod-S) dyno sheets for 3.2SS on this site, as there are many that have been done.

The GT2-102s are the cams that Jeff Higgins uses in his 3 liter, which uses small port heads. Here's a dyno sheet from before he got the car's AFRs dialed in...he's at least 20 horses and a good bump in torque on this one:



The DC44-102s are a favorite came of mine - I was the first to use them and John and I went back and forth designing these for a month. They've been so successful, they are now listed as a spec item on his site. For my 2.3L, they were designed to make 906 power, but without compromising on low end torque. They use a very aggessive ramp and .490" lift to get a lot of air into the motor fast. They ended up making 100HP/L at 7800RPM on the 2.3L and had a torque curve before 4000 RPM that looked like it was transcribed from a 'E' motor.

Given the propensity of larger motors to "soften" cams, you could expect these cams to make peak power around 500 RPM sooner, with torque everywhere. These cams respond really well to 38 or 39mm intake ports, but are perfectly happy with slightly smaller ports, which is why I suggested looking at them.

[jpnovak]

Your Euro 83SC should have the large ports. Keep in mind that you don't want to run a big cam if you can not support the intake airflow. The carbs will be fine but what about the head port diameters?

I agree that you will want twin plug. Compression ratio and large bore can create flame front issues with single plug. Besides, less timing is always a good thing.

I built a 3.2SS last year. I have 10.0:1 compression and twin plug. I run a DC40-108 in my car. The lobe center was set such that I have less issues with reversion in my EFI MAP signal. Peak torque is about 5800 with itbs and HP does not seem to fall much through 7100 (self imposed redline). I built the valvetrain to hold through 7500 or so but did not do the bottom end. My car pulls like a stock SC through 4K and then all comparisons are off. Just like any car with good cams it revs extremely quick at high rpm. I do not have any dyno curves. Its still on the list to do but not a priority of life. Really, the actual numbers don't matter to me. I just enjoy the "character" of the motor.

Jeff Alton used the DC44 in his 3.4. He reported peak HP just above 7K rpm and remaining flat through 7200. I don't recall seeing the dyno curve.

There are subtle difference between the DC40 and DC44 cams. For a street car I would go with the DC40.

[tom1394racing]

I'll just add this for consideration.

I run DC-60's in my 3.0 RSR spec motor. It is basically the same as Darren is projecting with ported heads but with 95 mm 3.0 10.5 CR Mahle P&C's. I run a down-stacked gearbox with reduced ratios for 3-5.

The set-up is just wonderful. 285 HP at the crank and runs right up to 8000 RPM.

From 1K to 3K it feels like my old stock '82 SC. From 4K to 8K at WOT, it accelerates like a sport bike.

If you open up the heads a little and match your gearbox to the 3.5K-7.5k RPM, power band, you can use the GE-60 cams and you'll be grinning every time you put your foot in the throttle.

[D911SC]

Originally Posted by tom1394racing

If you open up the heads a little and match your gearbox to the 3.5K-7.5k RPM, power band, you can use the GE-60 cams and you'll be grinning every time you put your foot in the throttle.

Are you using stock rods for this? From what I read 7500 is too hot for stock rods even with better bolts. Based on Steve's advice (Rennsport) that OEM and 7500 don't mix I don't want to be the guy that tests the theory!!

What gear ratios are you running?

I have already bought DC60's but may not use them, still haven't decided. One of the issues is driveability on the street which new gear ratios may resolve. The other issue is the added expense of making this thing survive higher revs that the DC60's need.

At this stage I am 99% certain of the other components so I will start to 'squirrel' these and make a final decision on the cams at the end. If I choose DC60s then they are there ready to go. If not I'll just have to sell them and put in something else like DC40s or GT2-102's

I really appreciate all the comments and contributions here. You guys have loads more experience and expertise than me so it really helps.

Anyone got some new 98mm cyclinders or PMO 46mm please let me know. I can arrange shipping at my end.

Darren

[Eagledriver]

According to Bruce Anderson, stock rods are good to 7800 RPM. I'm confident that with lighter pistons (JE's are lighter than stock) and any rod bolts (stock are fine here as well IMO), you could rev your street engine reliably to 7500 RPM. I race a "stock" SC motor with carbs and rev it to 7200 RPM with CIS pistons. The class I race in uses stock rods and some of our 2.7 engines rev to 7500 RPM and more. Use a rev limiter set to 7500 and have fun with your awsome motor.

-Andy

[BURN-BROS]

I place a 7500 rpm redline on stock 3.0 liter rods with arp bolts. It's a reasonable redline for those rods. If it was a 3.2/3.3/3.6 rod, I would not run them above 7000 rpm even with ARPs. FWIW a 72S redline is 7300 rpm with stock rods and bolts...same stroke as the 3 liter.

The DC60 is a great choice for the 3.0 liter/3.2SS. It brings back the early S feel that Porsche had to give up. With proper compression and twinplug ignition, it's a great combination. I perfer around a 40mm port for this combo.
Build it and enjoy!

[tom1394racing]

I manually limit my redline to 7500. Stock rods, ARP bolts.

It does require proper attention while accelerating as the motor will continue pulling right past 8K.

There is plenty to play with from 4k to 7.5K