Enlarging the displacement in 3.0SC engine ?

[Supi]

Hi there,

I am planning to stroke my 180hp 3.0sc engine and starting to collect information of the good combinations. the special interest is in Motormeisterīs 3.0 to 3.8 Big Bore Stroke Conversion Kit =>

6-New 3.8 Forged Billet Pistons
6-Biral Steel Lined 3.8 Cylinders
6-New Light Weight 3.8 Writ Pins
12-Spiral Racing 3.8 Piston Pin Locks
Hi -Compression
3.8 Stroker Crankshaft
Racing 3.8 H-Beam Connecting Rods
No More Cylinder Expansion
Increased Horse Power
Increased Longevity

Any experience of this scale displacement increase impact to rev limits etc ? how about the head...should I consider twing-plugging the current std head ? cam ?

I am using the Megasquirt EFI with the engine and the use case is street & track.

So all the hints are welcome regarding rear wheel power increase, torgue and driveability issues ? I donīt want built a turbo charged engine but I migt consider supercharger accompanied with 3.8 displacement if the engine block can tolerate charging.

so in short all the hint, dyno chart etc are welcome

Br

Sami (Finland)

[burgundyben]

How many HP would you expect to get from that set up?

[Supi]

Hi,

I am "dreaming" a bit over 300 rwhp with decent low end torgue as well to make driving in normal traffic ok as well.

Br

Sami

[safe]

Do a search on Motormeister and try and find a thread that doesn't compose largely of the words "suck", "bastards", "thieves", "a$$ holes" etc...

[Aurel]

First word of advise: I would stay away from anything having to do with Motormeister. They have a terrible and well deserved reputation going from bad customer service to fraudulent engine rebuilds. I would not even trust anything they sell. Anyways, I would use and abuse the search feature on this website, all the info is there. Here is a thread on the 3.6L motormeister kit to get you started...

MotorMeister 3.6 Big Bore Kit and Weber Kits

Aurel

[Supi]

Ok, got the point.. MM not the dream source (thanks regarding good hint anyway because I am not in US) . Letīs forget the source for a while and focus the basic questions to understand which kind of powerband etc I could expect if stroking to 3.6-3.8 (cam, heads porting, valves, airflow, EFI, etc....)
is +300 rwhp dreaming ?

hints and considerations ?

Br

Sami

[safe]

You will have to ditch the intake and get an ITB-system so you can use a cam that support 300+ rwhp.

[Aurel]

I think 3.7L is the maximum you can do with a 3.0L case, according to this thread:

Maximum bore on 3.0 911SC case?

In his book, Wayne describes such a 3.7L motor, and that will give you 280-300 hp.

Aurel

[Supi]

I think I was reading that article somewhere deep in www ...if I remember correctly it was still with original cis system when he was promisin 280-300 hp.

Br

Sami

[safe]

280 fwhp from a 3.6 CIS, probably possible.

Best bang for the buck is a 3.6 transplant, shouldn't cost you more than ~2-3000€ if you have a healthy 3.0 to sell.

[porschenut]

With that size cylinder and high compression, you will definitely need dual ignition.

[Supi]

what is the rule of thumb when to consider dual plugging ? any direct hints reflecting the cylinder size vs compression ?

Br Sami

[joetiii]

Originally Posted by Supi

what is the rule of thumb when to consider dual plugging ? any direct hints reflecting the cylinder size vs compression ?

Br Sami

regardless of compression, I've read that 98 mm cylinders is about the limit on single plu due to the time it takes for the flame to travel from sparkplug to furthest cylinder wall.

[kenikh]

Keep the 70.4mm crank and talk to Charles Navarro at LN Engineering about the biggest pistons and cylinders he can help you fit to a 3 liter case. You will be pleasantly surprised.

[YTNUKLR]

Getting a 3.6 is cheapest when you start with a 3.6.

[safe]

Originally Posted by Supi

what is the rule of thumb when to consider dual plugging ? any direct hints reflecting the cylinder size vs compression ?

Br Sami

If you stay at 95 mm bore 10.5:1 should be OK with single plug, if you have the same gas in Finland as in Sweden (98 euro octane). Higher and or bigger bore definitely twin plug.
Thats the advice I got from Swedish engine builders, but on the other hand twin pluging is always a good idea, not to mension good looking.

[kenikh]

98 Euro octane is a bad combination for 10.5:1 IMHO. Maybe OK in a Finnish winter, but not in US weather. Single plug US max is 9.5:1 on 91 octane (RON+MON)/2 - assuming Finalnd is RON only. Twin plug anything 9.5:1 and over on US gas.

[safe]

10.3:1 kompression on all euro 3.2 engines, so 10.5 isn't far off.

[kenikh]

Originally Posted by safe

10.3:1 kompression on all euro 3.2 engines, so 10.5 isn't far off.

Not on USA gas. Also realize that you are giving up timing for compression.

[safe]

Originally Posted by kenikh

Not on USA gas. Also realize that you are giving up timing for compression.

Yes, but neither Sami or myself are in the USA