different(?) late night motor idea....
 

I was just reading over some of the 3.0/3.2/3.4 engine rebuild ideas. So I came up with a few ideas and some questions along the way.

If I take a 3.0sc engine, put 98mm RSR high comp style pistons and cylinders can I put in a different crank to bring the displacement back down to 3.0 litres?

So go up in one way but bring it back down in another, I wonder though if the piston moves too far away from the head will the CR drop dramatically and if so is there way to bring the cylinder and head closer to the crank to raise the CR back up to around 12:1?

I have always liked the idea of a 3.0 RSR engine but thought by boring and destroking a 3.0 would give a very rev happy engine. Then throw MFI on top with twin plugs and have fun.

Has anyone done something like this or am I just flailing in the dark?

Henry has mentioned building similar 3.1 and 2.8 engines on the early turbo case before.

A 66mm crank and 98mm P&Cs would give you a short stroke 3.0. You would need a 930/02 or a 930/52 Carrera 3.0 or early turbo case to start with. I have no idea what the compression ratio would be but I think you would need custom pistons.

This engine combo would depend a lot on your driving style and how much street vs track time the car will see. MO. If you build a small displacement high rpm engine you will have to shorten the final drive ratio to keep it on-the-revs and install close ratio gear set to minimize rpm drop in-between gear changes. That will add big $$ to your build.

First off the case I would be using is a 78 SC. It would come out of my dads car and then he is either getting a 3.2 or more likely a 3.6. So I have this nice clean non leaking 3.0 to play with. I figured I can start stockpiling parts and when I have everything drop it out and rebuild it. I like to drive up in the revs and my car will most likely see a good deal of track time. The problem I see with the 66mm crank and then 98mm piston setup is con rods versus piston size. I would prefer to use a short skirt piston so I figure I would need some long custom con rods to make it all work.

Shoot, at this point Im thinking the 3.0 case, 3.2 crank and 98mm p&c's and call it a day. As far as the tranny goes it will get an overhaul when the engine is being built so they will play nicely together.

So I guess my question is would you rather have a rev happy RSR style 3.0 or a 3.4 with some low end grunt? I think the 3.4 would be much easier to drive on the street because milder cams could be used to get the same or more hp than the 3.0ss.

Ah the options!

Size matters!! Period!

Oh great, and everyone's been tellin me it's how ya use it. HAHA, yeah I suppose your right in some respects but I have heard pro's and cons to big and small motors alike.

if you already have a 3.0 litre perhaps you should build a 3.2MFI which with high comp and lightweight components the motor will be real revvy.

IMO


Michael

You have to use a 9 bolt 70.4mm or a 74mm crank with this case. I think you can also put a 3.6 (76mm???) crank in this case, but someone else will have to confirm.

Good idea, but dont forget the 3.2 Carrera rods. These are not the same 98mm pistons used to go from a 3.0 to a 3.2 short stroke. The 98mm pistons that were built for the 3.2 Carrera use a 23mm wristpin. Be prepared for an effective compression bump if you use them with SC heads or make sure you budget for twin plugs. Talk to 'rdane' if you go down this path, he's BTDT.

I want the rev happy motor, but I also want to drive it on the street. Not a good idea. If its a street car, Id drive the 3.0 until it broke.

good luck, and keep us updated as you progress

First off, I don't think you can put a 66mm crank in an SC motor unless you have the 962 crankshaft $$$$$$$$ with the 9-bolt flywheel end.

FOR THE AMOUNT OF MONEY, I would build this:
3.0-3.2 case
3.0 SC 9-bolt crank
USED but good high-cr JE/RSR/whatever pistons
3.2 cylinders, used
standard-port 3.2 heads (40/38--pretty big already)
Porsche factory 3.0 RSR 'Sprint' camshafts (4bearing)
single plug
Webers (46IDA)
I would think such an engine would a) be fine on the street, better than a 98x66 anyway, b) probably worth ~285 hp, c) it screams to 8k, and d) it actually has a spec. when you talk about it, ie. "I have a 3.0 RSR engine" and everyone knows what RSR means.... ;)
another option if you have money is to substitute in 98s, they're just more expensive but you'll have a short-stroke 3.2. MFI is another cool thing that is expensive.

oh, I forgot to mention to add $3k minimum worth of additional refurb and machine work if you want MFI on a 3.0 or larger engine. That doesnt include any of the core induction system.


I've been pricing this stuff out for a while, heres how it has broken down so far:

core pump - trade my 2.4 + some cash
rebuild core - $1000
core magnesium stacks - $200
core mag throttle bodies - $200
bore and rebuild throttle bodies - $1400
bore mag stacks - $400
linkage, injectors, cold start system - use existing
add drive gear to 4 bearing cam - $125
modify cam housing - still unknown ??
machine heads for MFI injectors - $350
PMO 46mm air horns - ????

I think I could do the MFI on my 3.2 short stroke for around $4500 :eek:. Keep in mind that I have a core MFI system to start with though. I would bet on it costing an even $5k if you dont have a good core system to start with. I hate to say this, but adding stuff like that up in my head makes me real happy I have a set of webers that are already paid for.

WOW, I really didnt think the MFI would be that expensive. Dad wants to ditch the CIS. At that point going the extra grand for an ITB EFI setup is a much easier step. That way if the engine changes again I dont have to pay to have the pump reclibrated. Just more options to explore.

I just ironed out some very base specs with dad over some makers mark.

Ditch CIS for MFI or Steve Weiner ITB setup with DTA or Motec.
3.0 or 3.2 displacement.
3.0 heads ported and polished unless a set of 3.2's at a good price come up
JE or Mahle higher CR pistons about 10:1
Happy cams to liven up the motor, midrange torque and high end power at the demise of low end grunt
SSI's and muffler will stay at this point.

I'm trying to convince him to go after a 3.2 and open it up to 3.4 we shall see!

Yeah, exactly my point. I always look at building engines FOR THE MONEY. When you build a 3.6 TWin turbo, yea sure you have 700 hp, but it cost you 25 large. That doesn't mean you were smart, it just means you have $$$$! Building a 3.2 with MFI is not NOT smart, but if you look at just how much power you get extra, and what throttle response, ITS GREAT! Until you get to the bottom line. $5,000--and that's what it costs. A cool but incredibly expensive way to go on the 3.0 + engines. I swear by the 46 Webers for such applications, they are big, they dump lots of fuel, you can run really hot cams and they are sub-$1500 if you are lucky!

Id love to go the carb route trust me but dad doesnt like the idea of tuning it for the weather changes, yeah and he told me to take the ac out? Kinda funny dont ya think?

So while I have your attention what is a reasonable price for a running and complete 3.2 with brain? Hopefully with the plastic intake runners, then just swap some 98mm p&c's on it, newer cams and a famous SteveW chip.

probably $5k easy, maybe $6k

HMMMMMM lets see, I can have MFI or ITB's on a 3.0 possibly 3.2 or have a 3.2 built up to 3.4, EFI, some cams and spend the same or less? Well I think that solved that problem haha.

BTW, I just looked over the gunnar racing website, god those 3.0 RSR engines look awesome, and the 935's, maybe after I win the lottery, a couple times.

Good luck either way trying to pass smog in California unless the motor(s) is going in a pre-76 car.;) Figure in the extra time and expense to put the car back to stock (or close to it) every 2 years.

Ralph

Ralph, the car in question is a 74 which makes me happy haha. BTW do you have any dyno numbers from your monster engine yet??? Very curious to see what kinda horses you are making with that oh so nice setup.

Is it much of a pain adapting a 74 harness to work with a motronic car? Do i need to change any of the guages?

I believe the elusive and expensive 959 crank is what would fit the bill. If I am not mistaken its 66 mm but would fit the later cases. It would be cheaper getting a billet crank made to spec. In between $4500.00 to $6500.00 should get you one made.

959 crank huh? that would be pretty cool to have in your car, a while ago I wondered if it would be possible to mate the 959 4valves water cooled heads to another air cooled engine, then wayne told me how much the heads are........

So here are my thoughts on the engine now. If we can find a complete 3.2 in good shape, put in the 98m ps and cs, wilder cams and a steve w chip.

2 3.2 longblock with lo miles, steve weiner itb/efi setup with 98mm p's and c's, cams, dta ecu.

3 take the 3.0 up to 3.2, fun cams, retrofit 3.2 plastic intake and ecu or steve weiner itb/efi setup.

Dad is leaning heavily towards the Steve Weiner ITB/EFI setup so i think the induction is nailed now. Because of that I would rather start with a 3.2 and go up to 3.4 with good midrange cams and the highest CR you can use single plug with.

All the race parts are relatively rare and expensive. You will find that you can be close to paying for tooling with the price of the part you wish to purchase.

Anybody done a 3.6 case/heads with 3.8 p/cs with a 3.0 crank and custom rods? That would be 3.5 shortstroke if it is possible.

That would be a mean little motor. Im not certain what case/crank/p's &c's henry used to get his 3.5 but it sure turned out to be a beast! Now that would be a nice engine, single plug, no insane CR, although the MFI setup im sure would be costly.

Go ahead and destroke the 3.0 litre crank. Using a honda journal size you can make it the 66 mm stroke. Pauter makes a nice rod for it.
Cost to do the crank work with re-nitride is about $1000,
I am not sure the cost of the rods.

John, how does it hold up? Any long term-severe duty feedback?

John that sounds very very interesting. Have you done or seen any cranks done up like this before?

I have seen a few done like this. By turning down the journal size the crank grinder can put in a huge fillet radius. Making the crank stronger. I know of one of these cranks spinning over 9000 Rpms.

9k+ is quite a bit of revs!! So john some cam questions for you please!

What cams would you suggest for these engines? All would have ITB/EFI and single plug with a desired CR of about 10.5:1

78 3.0 with above mentioned pieces

78 3.0 with 98mm p&c's

3.2 with 98mm p&c's

78 3.0 with 98mm p&c's with 66mm turned down crank

what im looking for is a good midrange with most of the power coming on higher in the rev range. For the super short stroke 3.0 that deserves all the high end power it can handle and I would build the valvetrain accordingly.

Right now the engine is a 78 sc 3.0 with 20/21 cams I believe but I actually think they may be 964 cams. SSI's and a very free flowing exhaust, 2 in 2 out. MSD 6al box and coil. Its very strong in the upper midrange, hard to set the idle in this "cold" weather too. It revs up to the high 7's, the power really comes on around 4k. Whichever engine we choose I am already set on where to get the cams, you sir. Your knowledge is tremendous and the fact that you spend time here on this board is what really sealed the deal.

I have read about cams over and over and still am a bit lost in the dark. Not good considering they are what really brings an engine to life. Sidenote, the first car race I went to, Long Beach Gran Prix in 98 I got to see the mechanics tear apart one of the penske engines. I still remember them paying extra attention to hide the cams from prying eyes. They let me look since cmon im a little kid with my dads huge camera around my neck. Compared to the other cams I have seen since then they looked really radical, Very strange shape on the lobes and a different color possibly material as well. I wish I had taken a pic haha.

Ryder, does your engine need rebuilding? If not, don't do this. Waste of money, man, because I bet in a year you'll want more power.

Wait until your engine breaks entirely, like someone else suggested earlier on this thread. Then get a 3.6. and a strong box. As is, that car just needs to be driven! SmileWavy

I will always want more power!!!!! If I had my way I would be building a 3.6L TT engine with 959 heads, del west pnuematic valvetrain, custom weismann sequential tranny (built the McLaren F1 trans) and on and on.

The engine has an unknown amount of miles on it, dad puts a lot on though, drives back and forth from pasadena to woodland hills 6/7 days a week on top of all over LA and our spirited angeles crest weekend runs.

I'm not certain, I need to take the cam covers off and look but I think it definately needs a valve adjust or possibly replace springs. When he bought the car we never got a definitave answer on the engine specs. He would rather build it sooner than later.

We are just finalizing design of the new engine so we can being buying up parts and start the build by feb/mar. Kevin just gave us a heads up on a car for me, fingers crossed big time, you know I need to get into an old Pcar. So we want to build this motor together at a good pace while we strip out "my" car and then swap the old motor in.

Basically, he wants a list of possibilities, prices and so on.
As soon as I am driving again I think a weekend fun run is in order, you, my dad and I and Kevin in his rear engined wonder! At least we can go hangout at a bar now that im 21! Hope to see ya soon and hope your car is still doing what she's supposed to!

ciao! ryder

Are we talking 91 octane pump gas?
for the first two engines I like my DC21 grind. The 3rd engine would like my DC24 cam.
The destroked engine I would run the DC42 on 110 lobe centers and run the engine 4500 and up. You will need head work and springs, Ti retainers etc. good fuel etc etc...

As far as gas I can run a mix. There is a 76 station here in pasadena that sells 100 octane. Ti retainers, springs, possibly valves I figured for the super short stroke 3.0.

pics
 

This is the motor in the rear end right now. 78 sc 3.0 with 20/21 or 964 cams, SSI's, 2 in 2 out banana muffler done up my Tyson at TRE, very good sound, 3 inch tips. MSD 6al with coil, new wires, chopped off airbox thanks to KevinP73's air tools!!! Not his fault, I did it. Stock CIS sitting on top. http://forums.pelicanparts.com/uploa...1102666391.jpg http://forums.pelicanparts.com/uploa...1102666432.jpg



So sooner than later that CIS will turn into ITB's

There are two ways to build a short-stroke engine using the 98mm pistons:

- Use a 962 crankshaft which has a large flywheel end, and a 66mm stroke
- Use a Euro Carrera or 1976/77 Turbo case and use an early crank (preferred). These cases run about $1500 or so.

-Wayne

Wayne, what is the reason for using those options over the 66mm destroked 3.0 crank? I assume that setup requires custom rods.

I haven't been directly involved with anyone who has destroked a crank. The cranks are hardened from the factory - anytime that you cut them, you will weaken them - you will need to renitride them. I assume also if you want to "destroke" a crank, then that would involve cutting the rod bearing journals to the inside of the crank and making them smaller. Yes, custom rods and custom bearings = huge PIA. Camgrinder mentioned that Pauter made some custom rods? They can't be too common, or too cheap though. Plus, you'll have smaller rod journals which will result in more force being placed on the bearings.

All in all, I'd say it's not a great idea. It would probably cost far more than a 3.0 Carrera case too.

-Wayne

Correction - it's a 962 crank, not the 959 crank. Well, actually, I'm not sure what the 959 crank is like, but I know that what you're describing here is the 962 crank...

-Wayne

Wayne, I would venture to guess that they are the same or similar cranks. The pics I have seen show no differences that you can readily observe. Possibly there are more "962" spares running around?

burn bros how is the twin plug coming along??

i agree that there are probably more 956/962 cranks around but you have to wonder what kind of condition they are in, then again its one of those unubtanium parts.

sidenote: just got the excellence mag today, there was an add for a semi tube frame 993 bodied car with a 962 engine.

also, pretty much finalized the engine build design.
3.2 case, crank, heads, rods, 98mm p's and c's around 10.5:1 actual compression or close to it, single plug, itb's and efi.
ssi's and exhaust will stay along for the ride.

so hopefully i will soon have a good 3.0 to have fun with.

Sounds like a fun engine. I think you are going to have to twin plug that motor. the CR will probably be OK but the pistons and bore will not. A 10.5:1 piston will have a very high wedge shape to it. combined with the large diameter this effectively divides the combustion chamber. So this leaves a flame front that has to climb a mountain. The flame front also has a large distance to travel in a 98mm piston. You will not have efficient burn and loose power. The residue left by the incomplete combustion will then lead to pinging. Just something to think about.

Mold has been preped at the injection molder and I will be stopping by to proof first article today or tomorrow (crossing my fingers).

Close to launch. Have sourced a fresh 3.6 motor for dad so hopefully I will have that torn down and rebuilt in the next month or so after his new brakes go on and I can FINALLY tear into his 3.0. I have a set of 993 3.6 pistons and cylinders laying around. Is there some way to make these fit onto a 78 3.0 case? or am I better off finding a 3.6 case and dropping a 70mm crank in it?