build a 3.0 into ???
 

I have a 3.0 SC motor that I want to build into something with big HP for my race car. I already have a fairly strong (315hp) 3.4.....

What can I build using the 70.4 crank?

1) SS 3.2 using 98's
2) SS 3.3 using 100's
3) SS 3.45 using 102's

Or use the 74.4 crank and make:

1) 3.4 using 98's (already have that)
2) 3.5 using 100's
3) 3.7 using 102's

The motor would be race only. Twin Plugged. Likely using my twin plugged 3.2 heads unless can get the 3.0 heads modified for a reasonable budget.

I would like to be able to retain my 48mm Jenvey ITB's, but would consider a switch to larger ITB's or to 50PMO's if required.

Have two sets of 1 5/8 headers already, but would go to 1 3/4 if required on a bigger motor.

High CR is fine, race fuel and twin plugs....

How about a cam for the different motors.

Not looking to spin it more that 7500rpm and 7250 will likely suffice.

Cheers

No replacement for displacement. I know you've heard that, but oh so true.

Trade some of the things you have and get bigger.

No need to trade, I have it all in stock available.

But was thinking of something a little different from the norm.... Maybe a 3.7 using the 74.4 crank, should get lots of bottom end with that motor.....

Cheers

Maybe a 3.7 using the 74.4 crank, should get lots of bottom end with that motor.....


Now were talkin'. lol

That was the original plan, still use the current 3.2 heads and maybe get away with the current 48mm throttles...... Bigger cams and headers and off we go!

Cheers

I have a 3.5, great motor!
Phil

Jeff: By limiting the project to 7200-7500 RPM you are answering your own question. You are negating the benefit of the shorter stroke crank by using that RPM Redline. The 74.4x100 is a good combination with a fair rod ratio. Using the new JE SRF (X box) piston at 12/1, a 149i Webcam (modified RSR Sprint), the 3.2 twin plug heads (should flow 260-265cfm out of the box) and 1 5/8 headers I would expect 330 FWHP at that rpm number. Stock rods with ARP bolts would be adequate at that number if no mistakes are made. The reason for the JE X-box forging is there have been complaints about the old 100mm forging failing.
Other choices are stroking the 74.4 crank to 76.4 and using the 102mm cylinders, (3.8) but I don't have direct experience with that configuration. I would certainly be wary of the cylinder spigot skirt thickness at 102mm in a intermediate stud spacing case.
aws

Thanks,

I am not too worried about the cylinders, they would Nickies from Charles and I trust he did his homework.

I will check out the cam you mention, but usually deffer to John D for my cams.

Cheers

For a race motor, I can't imagine using a lazy feeling crank like the 74.4. The 70.4mm is as long as I consider viable for a race car unless you happen to find a GT3 crank, which is a whole different story than the Carrera crank, POS 964 crank or (the admittedly much better) 993 crank. Nickies and JE FSRs all the way.

I say do the 70.4x102 and have John build you a custom DC90, maybe on 102 lobe centers, which is basically a higher lift RSR Sprint Cam.

*EDIT - saw you want to limit the motor to 7500...boring. Wanna be different? Spin it. :)

I say do the 3.7L. I always wanted to see more of those "experimental" motors but I heard they require a lot of work to get the large cylinders and pistons to work with that case. If I had the time and money that would definitely be on the top of the list for a cool/unique race motor.

Short stroke with the longest rods viable by design and spin the crap out of it.
If you want to use a 70.4 crank I have a 935 70.4mm crank. What's the difference you ask? the 935 70.4 crank has full counter weights. It looks much like the 74.4 crank. This 935 crank with 996 GT3 Pankl gen 2 rods (130mm) would allow you to twist the engine to close to 9000 rpm.
Now if 9000 rpm is not enough, we also have a 66mm crank.
Add 105 Nickies and either crank an wow!!!!

I am not married to 7500, but figured getting a cam that peaked out there would still give me some torque, which I need from 4K....

Ok,

What bore would you run with the 70.4 crank?

What do I get with a 66mm crank and 105's in terms of power/torque curve? 3.4L, are my current 48mm throttles enough? Exhaust? cam?

Cheers

A 66mm stroke 3.4L...could you get the valve train light enough to make it feasible to spin it to 8K?

Well, dunno?

Have Ti retainers and race springs, depends on the cam I guess?

Cheers

All of a sudden, the excitement I have on my bump is tempered. :o

I say supercharge or turbo. you can never have too much horse power, just too little traction or braking.

One thing about a 911, though in terms of power...it is very easy to have too little transmission. Big turbo power = big turbo "BOOM" on anything not a 4 speed (ick) or a G50 ($$$$$).

For the track I prefer the drivability of a NA motor. Yes, turbo = more power and I have thought about it, but like Kenik says, transmission issues would soon await...

Cheers

Sorry it took so long to get back.
I have no idea what kind of power/torque 66 x 105 would produce but what a hoot to build it. I will say that 8200-8500 rpm would be possible and given the correct port and cam configuration I would think you could produce good power from 4500.

That certainly does sound like fun Henry. Is there even enough seating surface on the 3.0L case to fit a cylinder that wide?

NO worries on the time frame!! I have a bunch more questions! :)

Hmmmm, 66mm counterwieghted crank I presume.

What size ITB and Exhaust primaries would you run?

Compression- 11.5:1 or higher (race fuel only)

What sort of cam in this beast?

How would 3.2 heads work in this engine?

You have tweaked my curiosity on this one!

Cheers

Talked to Charles @ LN and he says we could put 102 in an SC case.
102 X 66mm =3236 CC.

To run 105 you need a 964 or 993 case.

Supertec Super Crank
Note the lightened crank throws and hollow rod pin. This cranlk is designed to run the GT# Pankl ty rods. The are race tested at over 9000 RPM

http://forums.pelicanparts.com/uploa...1268752771.jpg
http://forums.pelicanparts.com/uploa...1268752787.jpg

http://forums.pelicanparts.com/uploa...1268752911.jpg

Henry,

Can you shoot me an email or PM and we can discuss the $$ for the crank and rods?

Thanks

The supercrank is 66mm stroke? For some reason I thought it used the GT3 stroke.

Hi Jeff
Contact me with a regular email address and I'll send you the info. Or call me
8-5 PDT T-F

BTW: The GT3 rods have gone through the roof. Porsche "gold" is always on the rise.

Stumbled across this thread... very interesting!

Any updates?

wow lots of good info, did any of this planing get put into actoin?

just listening and learning:D

I am switching from a CMW Stroke crank (77.5 STROKE from a ground 3.0 crank) with custom rods (130mm) and 100mm to a GT3 crank (76.5 stroke) and custom rods(131mm) to get back to the 3.7 I had, maybe a 3.8?.. $1800 for the crank is much better than the 4K for a CMW Billet, which due to the offset grind, can and will crackout.... Just need to figure the rod lengths..

searchin for a "what to do to my motor next" and stumbled upon this thread. Whadda tease. it gives me wood. Anything get built?

We have our GT3 crank now, and will be ordering custom 131mm rods, either Carrillo, Cunningham, or R+R, depends on weights. Anyone else doing a similar build?

Our project changed directions, motor is gone, had a HP twin plug 3.0 turbo motor, but it is still on the stand and likely to be parted out...

Cheers