2.3 Twin Plug Engine is Done

[CamBiscuit]

Its alive!

My mechanic called me today to say they had run it up on the dyno this morning.

It made about 178hp at the rear wheels and was still rising before it hit the rev limiter on the MSD box which was set at 7300. As the cams make power up to about 7600-7700rpm and the rev limit will be around 8000 there should be a few more hp to be found yet! Unfortunately they thought the MSD was the chipped type instead of being adjustable so it didn't get another run up past 7300rpm.....This has now been corrected!!

Using the Porsche Cup formula of rear wheel hp x 1.32 thats around 234hp!!!!

He also said they may play around with the jetting on the carbs a little more, once it has some mileage on it.

I have a track day at the Racetrack on Thursday which I'm rather looking forward to! I'm a long way from the car at the moment and am on the plane tomorrow....can't wait!

[CamBiscuit]

Engine specs are as follows:

• 2.4 7R 911/91 case, shuffle pinned, oil bypass mod, 996 turbo pump, case savers, resurface & line bore (thanks Tom Butler and Competition Engineering)
• 66mm ‘S’ counterweighted crank , cross drilled, balanced magnafluxed + micro polished (thanks Kenik)
• Pauter rods (thanks Cole Scrogham)
• 10.5:1 JE pistons – mechanics special recipe
• Nickies 85.5mm barrels (sized to racing regs here)
• DC 44 Cams on 102 degree lobes (thanks Kenik)
• JB Racing Twin plug distributor
• Supertec head studs
• Heads ported, racing valve springs & titanium retainers (thanks Steve Weiner)
• Webers with tall secondary venturis, port matched tall PMO manifolds
• Aussie made ‘Cairns’ muffler
• Single MSD

[Mike_Moore]

sounds fantastic Cam, have a great day on Thursday and don't forget the camera!

[letsrollbabe]

Cam:

Congrats on what from the specs looks to be a great 2.3L twin plug engine, very similar to the STs of the day. It will be a blast to drive I am sure, and the sounds should be wonderful. I agree with Mike...pictures of your new beauty would be really fun to look at.

Gib

[RSupdate]

Its alive!

My mechanic called me today to say they had run it up on the dyno this morning.

It made about 178hp at the rear wheels and was still rising before it hit the rev limiter on the MSD box which was set at 7300. As the cams make power up to about 7600-7700rpm and the rev limit will be around 8000 there should be a few more hp to be found yet! Unfortunately they thought the MSD was the chipped type instead of being adjustable so it didn't get another run up past 7300rpm.....This has now been corrected!!

Using the Porsche Cup formula of rear wheel hp x 1.32 thats around 234hp!!!!

He also said they may play around with the jetting on the carbs a little more, once it has some mileage on it.

I have a track day at the Racetrack on Thursday which I'm rather looking forward to! I'm a long way from the car at the moment and am on the plane tomorrow....can't wait!

What is the "Porsche Cup Formula" for determining rear whl to Flywhl h.p....? just multiply by 1.32?

never heard of anything like that, but there's a lot yet for me to learn, so plz...educate this old salt !!

I always went by the old 15% loss rule.....and 10% for straight cut gears....

I'll always be learning.....

[kenikh]

At least I now know what I forewent when I sold off these cams. Cam's motor is the identical spec to what I was building. What's sad (for me) is that if I had stayed the course, I'd be the done and writing this thread. LOL!

Great news Cam - I was very curious to see if my calculations and specs would pan out like I had expected. It appears that they have indeed.

Drive it like you stole it! Cheers.

BTW, I still have the George Narbel headers that were custom designed for this motor, gathering dust on my shelf...just sayin'.

[kenikh]

What is the "Porsche Cup Formula" for determining rear whl to Flywhl h.p....? just multiply by 1.32?

never heard of anything like that, but there's a lot yet for me to learn, so plz...educate this old salt !!

I always went by the old 15% loss rule.....and 10% for straight cut gears....

I'll always be learning.....

I use the 15% rule, too, so the adjusted number is 204 at the wheels, but also realize, there's a lot more power in the next 700 RPM. These cams don't fall off the top of the HP curve until 7800RPM.

I always estimated beak power to be 225HP @ 7800RPM using MFI. 234 would certainly exceed that.

[a911s]

For our 911 motors using a 915, divide the rear wheel HP (or torque) number by .85 to arrive at approximate flywheel numbers.

[CamBiscuit]

Cheers Guys

The formula seems to be what a few guys run off down here, and yes it may be optimistic but as it is Porsche based it seemed to be the best way to convert. Possibly a little optimistic i'm not sure but geez it feels good! Randy the trans is a 901/911 with a LSD. Not sure if the LSD makes a difference to figures?

My first impressions today in a suburban environment where I wasn't able to spank it very hard were very good Pulls well down low and goes bananas from around 4500rpm. I don't think I was able to take it much above 6500 today so tomorrow should be rather interesting!

I was even having fun just looking at the nice new looking engine with the extra spaghetti Looks fast just sitting still!

[CamBiscuit]

Photos & track footage will be forthcoming, no doubt about that Mike!

Kenik you just keep throwing temptation out there don't you