Quick FAQ 3.0/3.2 upgrades to 3.2/3.4

[ChrisBennet]

Originally posted by geof33
Ok,

Now I'm thoroughly confused!! I'll be increasing my displacement from CIS 3.0 to Weber 40 carbed 3.2... Steve at Rennsport has 95mm nik pistons/cylinders at 3.2 for this setup running at 9.5:1... Was I mistaken? Or are things different when running carbs? Would the stroke issue be the same?

I'm not sure what the question is but I'll just shoot some info out there and hope I hit something:

3.0SC = 95mm bore, 70.4 stroke
3.2Ca = 95mm bore, 74.4 stroke

3.2SC = 98mm bore, 70.4 stroke
3.4Ca = 98mm bore, 74.4 stroke

-Chris

[geof33]

Chris,

The confusion was the 95mm size. Perhaps I was not paying close enough attention when emailing Steve. Can one do 9.5:1 with 98mm 3.2sc short stroke pistons?

[smdubovsky]

If using J&E pistons, you can do ANY CR you like in any diameter. I have 100mm cyls w/ J&E 10.7:1 in my twin plug SC = 3.32L. About 1.5% smaller than a 3.4 (which is really 3.37L I might badge it as a 3.4 so people don't think its a turbo.

SMD

[rdane]

I am running a 3367cc with 98 P&Cs and a 3.2, 74.4 stroke. Typically called a 3.4 long stroke...

Badges? "We don't need no stinking badges"



You have to tell them if for no other reason than to stop them from crying

[matty74]

What is the most agressive cam sharft profile for MM 9.3:1 pistons?

for CIS

and for webbers

[Porschekid962]

Is the 3.3 short stroke the black sheep of the bunch? My father and I just finished one, the dyno numbers were not conclusive but certainly impressive. HP was going up and up and up when they cut the run at 6800 but the cams (john dougherty) were specced for about 7500rpm peak power. The torque was well more than I expected, 299.7ft/lbs at the rear wheels at 6700rpm. Not too bad with stock 78' heads and a couple other add ons....

My dream is to take this motor to 3.5litres with big port/valve heads, racey cams, bespoke intake, bespoke exhaust and a lot of other fun stuff inside. Hoping for numbers equal to or greater than the numbers Henry got from a single plug MFI motor he posted here ages ago. I still have the thread bookmarked if anyone is interested.

Matty, if you are choosing between CSI and Carbs, for performance go with carbs anyday of the week. You can run hotter cams and get more power. With CSI you need to strip it down and warm it up for a bit before driving if you have hot cams. I know, I did it for a while.

[crashmy911]

Can they bore 3liter cylinders to take 98mm je pistons?

[Jeff Alton]

No, the issue is the sealing ring that is present in the tops of the 3.0 cylinders. However, you can substitute a set of 3.2 cylinders bored to 98mm.

Cheers

[JCstomper]

Originally Posted by Jeff Alton

No, the issue is the sealing ring that is present in the tops of the 3.0 cylinders. However, you can substitute a set of 3.2 cylinders bored to 98mm.

Cheers

So you essentially could get a set of used 3.2 cylinders, bore them to 98mm, and use them with the correct pistons on a original 3.0 engine? I want to make sure im reading correctly

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[Trackrash]

Originally Posted by JCstomper

So you essentially could get a set of used 3.2 cylinders, bore them to 98mm, and use them with the correct pistons on a original 3.0 engine? I want to make sure im reading correctly

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Yes, or you could order sets already made or buy Nickies. https://lnengineering.com/products/aircooled-cylinders-pistons/porsche-911-1978-98.html?p=2

There have been lots of SC cylinders bored, but as mentioned there have been reports of failures.

I think our host sells some of these sets, but I had no luck searching their parts catalog.

[Jeff Alton]

Yes,

EBS likely has core cylinders available, or buy a complete Mahle set or LN Engineering with your favourite piston.

We just recently assembled a 3.0-3.2SS where we used bored and plated 3.2 cylinders (98mm) and a custom JE piston. We also have built quite a few 3.2-3.4 bored the same with either a JE or CP piston.

Cheers

[Geronimo]

Every time I step into an engine build thread in hopes of finding a way to make my 3.0 a stout lil beast... and here I am reading about 175HP uuuug what a useless lil lump of an engine.

[Trackrash]

FWIW, I still have a bruise on the back of my head from the time I got a ride in my friends car with a 3,0, dynoed at 250 hp, when he shifted from 1st to 2nd.

[Geronimo]

250HP must have been pretty much a full race build to get that out of a 3.0L

250HP is starting to get into the fun range IMO

[JCstomper]

Originally Posted by Trackrash

FWIW, I still have a bruise on the back of my head from the time I got a ride in my friends car with a 3,0, dynoed at 250 hp, when he shifted from 1st to 2nd.

I have a 800+whp awd VW... I dont need crazy HP in this car. It's so light and fun, completely different type of driving.

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[Trackrash]

Originally Posted by Geronimo

250HP must have been pretty much a full race build to get that out of a 3.0L

250HP is starting to get into the fun range IMO

250 HP is relatively easy to obtain. Actually, I miss spoke, his motor is 259 hp, and that is with a stock muffler. I asked him why he didn't have a sport or custom muffler, since that would add another 10 hp easily.

Here is the other end of what is possible to do starting with a 3,0. My new build, the last of a long but very FUN journey!!!

[Geronimo]

What is he doing to get 259, dual plug, high comp, big cams I would assume.

[Trackrash]

Only mods are 10 to 1 CP pistons, some big Elgin cams, (he wasn't sure of the specs), single plug, Weber 46s.

He had someone dyno tune and break-in the motor, including re-curving the distributor, and the tuner was confident there was no detonation, due to the cams overlap.

He wasn't spinning the crap out of it either. At the time he had his limiter set at 6500. It is in a 914, so a hundred pounds or so lighter than my car. FWIW my car feels nearly as quick, however he took TTOD at his first AX with it leaving me in the dust.

Also a known engine builder I know in SoCal, was claiming 260 out of an SC motor he built with only cams, exhaust and weber 46s changed.

In Bruce Anderson's book there is a dyno chart of a SS3,2 with around 260 HP with Weber 40s and usable torque at 3000 RPM.

Read the link I put in #56 if you want see what is possible starting with an SC motor and $$$$.

[mepstein]

Originally Posted by Trackrash

Only mods are 10 to 1 CP pistons, some big Elgin cams, (he wasn't sure of the specs), single plug, Weber 46s.

He had someone dyno tune and break-in the motor, including re-curving the distributor, and the tuner was confident there was no detonation, due to the cams overlap.

He wasn't spinning the crap out of it either. At the time he had his limiter set at 6500. It is in a 914, so a hundred pounds or so lighter than my car. FWIW my car feels nearly as quick, however he took TTOD at his first AX with it leaving me in the dust.

Between the weight advantage and the engine placement, it's hard to beat a 914 for auto-x.

[Geronimo]

yea, with a metric ton of money anything can make power LOL.

I am trying to figure out what path makes the most senes for my future engine build... 3.0 low comp and a turbo,

3.2ss

or check out the 3.0L and sell it for a 3.6 swap.