DC 30 cams in a 911RS 2.7 MFI

[HKZ Bob]

Hello Forum,

is somebody in the forum drives the dougherty DC 30 cam in a 911S 2.7 MFI.

I would like to know how it performes compared to the oem cams.

BR
Bob

[BURN-BROS]

Torque comes in around 3000 rpm and is all done by 6500rpm or so. Good broad usable torque. Better lobe centers and beter dynamic compression than the old school cams.

[HKZ Bob]

Originally Posted by BURN-BROS

Torque comes in around 3000 rpm and is all done by 6500rpm or so. Good broad usable torque. Better lobe centers and beter dynamic compression than the old school cams.

Thank´s do I have a power loss of the 210HP with the DC-30 Cams?

BR
Bob

[larrym]

.

before you do anything else - it would be instructive to us all if you'd put that car on a chassis dyno & post the results


I have never understood how Porsche could wring out 210hp from 8.5 CR - but am inclined to think it is a magic combo that can only be mucked up by changing anything internally

presumably the RS P&C's should be 8.5CR - same as i have

did you already do something else to increase the CR ??

my torque comes on at 2800 with Solex grind & webers - winds to 7000 - i have dyno sheet

I was at John's shop last week -

for my 2.7 with 8.5 CR & webers he said DC30 is too much cam for such "low compression"

- he recommended E grind instead

John said torque should come in about 600 earlier with the E grind

he also said it should run on 87 pump gas with that setup

for me - that gives a 'way better street & AX solution.

cost me $345 for that on my .143 .144 CIS cam cores - DC30's would be the same price - John has cores for sale


.

[BURN-BROS]

Originally Posted by HKZ Bob

Thank´s do I have a power loss of the 210HP with the DC-30 Cams?

BR
Bob

Hi Bob,

If all aspects of the engine are identical then yes, I would expect less Peak Hp.

[cmcfaul]

The DC 30 cam are designed for a higher compression motor, 9.5 CR or higher. With these cams you will lose some compression due to increased overlap but make up for it in VE (volumemetric effeciency). So for a low compression engine E cam are prob best. 9.5 or higher CR and the DC30's I have make power from 3k up to 7300+. From 6k to 7K RPM's the Tach moves the fastest.

Chris
73 911 E

[911231]

I am currently building a 2.7 rs spec mahle 8.5 cr, mfi (rs spec) with ssi for a street driven 72s targa.
after talking to the camgrinder I had decided on the DC 30 because of the broader torque range. I had not heard that the dc 30 was for a high compression setup before. John D did not say anything about that when I talked to him.
What would be the differences be in this motor with dc 30 mahle 8.5 cr or dc 30 je 9.5dc?

[cmcfaul]

why not increase the compression? It will give you more HP and compliment the DC30 cams. See previous post. Talk to John Daugherty. I am basically paraphrasing what he told me during my build.

The difference between this set up with 8.5 vs 9.5 CR will be significant. guessing 20 +hp. You will get HP from the higher compression you will also get HP through higher VE with the DC30's. The DC 30's will be better matched to the higher compression pistons resulting in optimization of both components. I would not recommend using the DC 30 on a 8.5 cr motor. Effective CR at low RPM's will be very low.

Chris

[911231]

That seems to make sense to me if there are no downsides. Any guesses as to octane requirements
Thanks for your input
Al

[cmcfaul]

Super unleaded only. Keeps temps down. colder plugs. not too much advance.

chris

[911231]

Thank you. I think that is what I will do
Al

[camgrinder]

Originally Posted by 911231

What would be the differences be in this motor with dc 30 mahle 8.5 cr or dc 30 je 9.5dc?

All depends on the powerband you want. They will work with 8.5-1, but you will down on power before peak torque. In other words with the 9.5-1 slugs the engine will come on the cam sooner vs. 8.5-1. More mid range. At the HP peak you might see only 6-7 hp between the two.
If you assume the compression is 8.5-1 without measuring everything, and end up with 8-1, well its not going to be fun to drive.

[911231]

Thank you John, That is the information I was looking for