induction for DC80 cams

gumba · 10-18-2006, 04:25 PM

I'm using Elgin DC80 cams in my 3.4 twin plug. Is there a preferable induction system that theses cams work best with, i.e. Weber, PMO, EFI. I'm currently using 46mm Webers.

kenikh · 10-18-2006, 04:37 PM

As long as you are using something with individual throttles, you are good. EFI will almost invariably be smoother due to electronics.

rsscotty · 10-18-2006, 05:32 PM

If you sell the Webers and do something like in the picture below,which is a 3.6 resonance style intake, you will gain big time in the mid range torque department. The picture is with single oversized throttle body, no mass air flow or air flow meter.

If you go with individual throttle bodies, this makes the throttle response very fast and crisp. Of course EFI is a must with this intake setup. We use Motec or DTA.

The other option is our high butterfly intake system which would be best if the engine was always above the 5,000 rpm range, as in a race setup with proper gears..

kenikh · 10-18-2006, 05:52 PM

Are you saying you can make DC80s run on a common plenum intake? I've even seen one of the best Motec wizards in the biz brought to their knees trying to make those cams work on a VarioRam. They got the VarioRam running like a charm, but couldn't tune the motor to get the reversion out enough to get the intake to work without MAJOR flat spots.

gumba · 10-18-2006, 06:22 PM

It's a race motor with the proper gears. The weber stuff is getting harder and harder to find. I'm looking around for other options.

rsscotty · 10-18-2006, 07:34 PM

With a common plenum like the 3.6 plastic intake or the Varioram, the hottest cam we have used is the 993 Euro RS to maintain a decent idle speed. The 993 Supersport Cam made decent power, but no idle below 1200. So...no I haven't used this common plenum with the DC80 cam.
Could not find specs. for it through Elgin..maybe it is an older number.

With individual throttle bodies added to the plastic intake, I believe the Web Cam 171/149 grind is the one that comes to mind...no problems with any part of the tuning.

And of course the 3.8 RSR cam with the resonance intake and individual throttles has always worked well.

Getting back to the original question from gumba, since it is a race motor, the high butterfly intake would work well and is compatible with pretty much all race cams. I can post photos if interested.

gumba · 10-18-2006, 07:41 PM

I would like to see some photos. What is the advantage of the high butterflys over the webers?

rsscotty · 10-18-2006, 08:28 PM

The advantage over Webers would be in the combination package of complete control of the fuel mixture and ignition timing throughout the full rpm range, regardless of throttle position. You also have the option of going bigger than 46mm, but you could do this with PMO carbs. also. If you want to update to a carb with parts availablity not being a problem, then the PMO would be the way to go. This would also be the lowest cost option. Carbs. whether they are Webers or PMO always have the rich fuel mixture at mid rpm range that costs alot of power and can't be tuned leaner without the mixture being too lean from 5k up.

We designed this intake based off the early RSR intake with high injector placement hoping for better fuel atomisation, in conjunction with the longest intake track that would fit in the engine bay. Combined with the programmable engine management, you get precise fuel control, injector timing placement, ignition timing exact to within .2 degrees along with useful data logging.

We also have our own billet throttle linkage system that is very clean and functional. The pictures are of a 3.8 liter, but we have stacks for the 3.4 two bolt intake also. Hope this helps.

Bryan Beaumont · 10-20-2006, 08:35 PM

Looks good Scotty. New world meets old. Gotta love the high
butterfly look, and the improved atomization is good for 10 to 20
HP, supposedly. Do you have any shots of the complete stacks
without air cleaners?
I've seen a couple of guys take factory Porsche high butterfly
MFI and convert it to work with Motec. That look is the ultimate
but, out of my league money wise.

kenikh · 10-21-2006, 12:02 AM

Quote:

Originally posted by rsscotty
With individual throttle bodies added to the plastic intake, I believe the Web Cam 171/149 grind is the one that comes to mind...no problems with any part of the tuning.

BINGO. Great idea.

gumba · 10-21-2006, 07:07 AM

I think one of my friends may be running this system on his 3.8. He has the same linkage set up. Did Jeff Gamroth have something to do with this system.
Any advantage over the TWM/Electromotive set up? Whats the cost. You can pm me if you prefer.

DW SD · 10-21-2006, 07:59 AM

Quote:

Originally posted by rsscotty
With a common plenum like the 3.6 plastic intake or the Varioram, the hottest cam we have used is the 993 Euro RS to maintain a decent idle speed. The 993 Supersport Cam made decent power, but no idle below 1200. So...no I haven't used this common plenum with the DC80 cam.

Scotty,
What is decent power with plastic intake and 993 SS Cams in your view?

I have a 3.6, 964 bottom end w/ 993 heads, 964 cam towers, 993 SS cams and '95 DME engine management and actually do not have idle speed issues.

I have a conversion flywheel (to 915 trans) for my early car. It is a Patrick Motorsports flywheel (as opposed to DMFW.

Doug

DW SD · 10-21-2006, 08:01 AM

Also, how do you setup the ITBs w/ the plastic intake? And why would you do that, rather than simply ITBs alone?

Do you gain from the resonance design?

Doug

rsscotty · 10:23 AM

Gumba,

Yes, Jeff Gamroth owns Rothsport Racing in Tualatin, Oregon and I work with him on a daily basis. Our in house Superflow dyno is where we do all of our development work. The TWM throttle bodies are just ok, probably one of the first for Porsche engines with EFI. We have two 3.8 liter engines with these installed, but have not used them in four or five years. We don't care for the linkage system, since it is just like the carb. setup and more difficult to adapt the later style throttle cables. Our stacks are of a different total length with different injector placement, and along with our linkage setup suits our needs the best. Our throttle bodies are Jenvey, which alows each cylinder airflow to be adjusted for optimal idle smoothness. We can also order these in different sizes depending on our engine needs.

As far as our thoughts on the TWM/Electromotive setup.....we prefer DTA for the reasonable cost, and with this system you have a very reliable total engine management system that we can tailor to any engine configuration. We also make our own wiring harnesses in house out of the same materials you get from Motec. We also use Motec engine management....but this system is more money. Certain engines get it.....depends on the customer preference and budget of course.

DW SD....I will post more info. later regarding your request. I'll see if I can post a dyno sheet on a 3.8 plastic intake with Motronic.
I do recall a 3.8 we built for a RSA with DTA. It put out around 338 HP on the engine dyno, but would not idle low enough with the 993 SS cams to go through Oregon emissions test. So we settled for the same engine with Euro. RS cams and Motec, which got along well with the idle stabilizer valve setup. Went through DEQ with no problems, cats and all.

Scotty

gumba · 10-21-2006, 11:07 AM

Thanks for the reply. What is the cost for the system. How much adjusting is needed from your settings based on my motor to actually fine tuning it on my motor (since your up there and I'm down here, SF/Bay Area). I'm using a 3.4 twin plug.
This system came on a 3.8 race car a friend bought last year. A very nice looking system.

rsscotty · 10-21-2006, 06:29 PM

gumba,

As far as prices go, please call the shop and talk with Jeff. He does all of the billing for parts and labor. He would be glad to talk with you and discuss your upgrades. Phone 503-885-9626.

As far as tuning, each engine is different as far as the map. We can spend up to a day or two on the dyno, depending on if we are changing exhaust systems or searching for more power.
The wiring harness is made for each specific engine, as there are options on coils, whether or not we are running a distributor or one coil per plug etc. You can tell Jeff what is on your engine...he can tell you what parts we can work with and what would be needed for the conversion. Crank trigger systems, sync. systems..depending on if you go sequential injection or group fire.

Some people ship us their engines, some ship us their cars. It depends on what each owner wants to do themselves.

Hope this helps, Scotty

rsscotty · 10-21-2006, 06:50 PM

DW SW

We have an adapter to go from 2 bolt intake cyl. heads to the individual throttle body, and another adapter to go from the top of the throttle body to the 3.6 plastic intake. See attached photo. Excuse the long plug wires, but this was the first single plug, coil on plug Motec setup, and Clewett made the wires a bit long since the coils were originally going to be mounted further away.

If it is a 3.6 three bolt intake, we have those adapters also.
The individual throttle bodies have tremendous throttle response compared to a single throttle body. A single throttle body would be more suited for a street engine, the individual for race. It all comes down to how you want your engine to respond, and of course budget. A single throttle body works well if you don't want to spend the money for individual, but we would have to add a idle stabilizer to the system.

camgrinder · 10-22-2006, 08:38 AM

Quote:

Originally posted by rsscotty
no I haven't used this common plenum with the DC80 cam.
Could not find specs. for it through Elgin..maybe it is an older number.

The DC80 cams are made by me. The specs are here,
http://www.drcamshafts.com/911profiles.htm

I like the 46 or 50 PMO carbs with these cams.
What kind of powerband are you looking for?

gumba · 10-22-2006, 09:19 AM

Hi John,
The motor is a 3.4 twin plug, 10.5 comp ratio, euro headers, Eletromotive HPV-1, race motor built by Henry. The power band seems to be 5000-7000 rpm (my shift point) Henry estimated the h.p. in the 300-320 range. I'm currently using 46mm Webers. Someone local said your cams would work better with the PMO's vs. Webers. I thought these were your cams, but the built sheet said Elgin.
Didn't know if I should consider going to PMO's, what gain, if any I would get.

camgrinder · 10-22-2006, 09:30 AM

If your happy with 5000 to 7000, keep the 46 webers. IF you want to move the shift point up, go with some 50 pmo's.
I do change profiles for the pmo's vs. webers. I might do a DC80-104 instead of the DC80-100. the -100 is the lobe seperation angle. The 104 angle stretches the powerband and works better with PMO's. Doesnt work to well with Webers.