Short Stroke 2.8

[JackMan]

I just stumbled onto this thread after a search for 2.8SS. Thanks to all that shared their knowledge. I have a fairly rust free 1970T chassis with steel turbo fenders front and rear. I've been searching for the "right" engine for it. The quick solution is to build a 3.0, put on PMOs and trot around. But with this BAD BOY I can prance around all day long. Thanks Henry!

For all those with knowledge, if I were to build this 2.8SS using PMOs instead of MFI, would I need to change any of the intake/exhaust sizes?

[faapgar]

Hi,in the mid 90,s I started using the early 3.6 heads on my 2.8 ss engines.I had been using 3.2 heads which worked quite well.I use Ti valves that are larger as well.Also ti-rods that are 132mm long to get a 2 to 1 rod ratio.Stud spacing needs to be narrowed a little bit on the heads.I use a 3.2 repair head gasket to seal it up tight.930 104 381 01 and there are no leaks.This motor spins to 9300 rpm and makes 248 ft.lbs. of torque with a very long flat torque curve.Outer portion of the piston is trimmed to get proper head clearance with the longer rod.Like Henry said the best motor that Porsche never built.I use 45mm slides with Motec and a hand built step exhaust to let it breath.Makes 374 H.P.at 9300.Power starts to drop off a bit a 9100.It is simply a stunning engine and revs way quicker than larger motors.Fred

[m42racer]

Originally Posted by faapgar

Hi,in the mid 90,s I started using the early 3.6 heads on my 2.8 ss engines.I had been using 3.2 heads which worked quite well.I use Ti valves that are larger as well.Also ti-rods that are 132mm long to get a 2 to 1 rod ratio.Stud spacing needs to be narrowed a little bit on the heads.I use a 3.2 repair head gasket to seal it up tight.930 104 381 01 and there are no leaks.This motor spins to 9300 rpm and makes 248 ft.lbs. of torque with a very long flat torque curve.Outer portion of the piston is trimmed to get proper head clearance with the longer rod.Like Henry said the best motor that Porsche never built.I use 45mm slides with Motec and a hand built step exhaust to let it breath.Makes 374 H.P.at 9300.Power starts to drop off a bit a 9100.It is simply a stunning engine and revs way quicker than larger motors.Fred

All I can say is .....wow!!!!

Back in the day I raced a 3.8L 993 RSR with what I was told had everything including the sink thrown at it. It made just over 400 BHP. It also ran out of gas at just over 8200 RPM. Your engine makes almost as much one whole litre of displacement smaller and still makes power almost 1000 RPM higher.

You sir, need to go looking for the holy grail. You will probably find it!!!

[Henry Schmidt]

The latest adventure into short stroke magic was the 3.1 liter engine we built for a customer in the US military stationed in Sicily.
Supertec 3.1 liter Short Stroke 9000 RPM 2 valve
1982 930 Turbo case (GT3 squirters)
Shuffle pins
Boat Tail
Supertec SuperCrank billet 66mm full cross drilled
R&R billet connecting rods (GT3 config: 53mm big end, 21mm small end & 130mm oal)
GT3 Bearings coating by Calico Coating
996 TT oil pump
Racing IWIS chains Supertec idler arms
964 steal countershaft
Supertec Head studs
LN Nickie cylinders 100mm
Supertec 906 cylinder tin
11.5:1 JE FSR pistons, 60 grams lighter than conventional pistons
Custom DC 90 cams
Early forged rockers w/dry film pads
Xtreme Cylinder heads
50mm PMO Carbs (manifolds 47 x 50mm)
Burnham Motorsport Twin plug distributor
Burnham Motorsport sump cover
Series 900 fan shroud
Supertec Power Pulley
Supertec RSR flywheel

Originally Posted by Xtreme

Port Flow Analyzer v3.0 XTREME CYLINDER HEADS
Test Comments:
Vlv Dia
1.850"
1.575"
Stem Dia.31"
Lift Range Test Flow Leak Corr Pres Pres CFM
Int #1 .100 4 28.00 34.00 .0 67.7
Int #1 .200 4 28.00 79.00 .0 157.2
Int #1 .300 5 28.00 73.50 .0 216.8
Int #1 .400 5 28.00 84.00 .0 247.8
Int #1 .500 5 28.00 89.50 .0 264.0
Exh #1 .100 4 28.00 25.00 .0 51.3
Exh #1 .200 4 28.00 53.00 .0 108.7
Exh #1 .300 4 28.00 75.00 .0 153.8
Exh #1 .400 4 28.00 87.50 .0 179.4
Exh #1 .500 4 28.00 93.00 .0 190.7

[faapgar]

Wow,great motor.Heads are just gorgeous.What does a motor like that cost roughly?Did you dyno it?I built a few 3.1 ss for Imsa 911 in the 80,s & the limiting factor was enough fuel .We used the Kugelfischer Rotory pump as well.Beautiful build Henry.Fred

[Canada Kev]

Originally Posted by Henry Schmidt

The crank can be fitted into any case from 78 to 97.
The cranks use a more modern oiling design and are considerably lighter than conventional Porsche cranks. To build a 66x102 you need a 964 or 993 case unless LN makes a Nickie that is a 102 with a 105 spigot.

I believe LN does make 102 cylinders / 105 spigot for 3.2 cases. However, wouldn't that make for rather thin walls at the base? Would that make for an inherently weak area or is it a non-issue?

[JackMan]

subscribed

[DRACO A5OG]

Originally Posted by Henry Schmidt

Wow, I am really digging those rod holders to mate the case halves, nice. Any chance of getting a close up of those things, purty please.

Love that oil plate

Were the heads chamfered for the 100 Nickies? Nice

[parts4porsche]

I don´t know if I asked you before Henry, but why not, 70.4 stroke with 102mm pistons on 993 case? that would make same bore/stroke ratio as the 2.8SS we can have all the benefitt of the 2.8 plus we can have twin plug for free.

I have all the parts to build it, to my twin turbo engine. Ti rods from Pankl, turbo oil pump, or GT-3 oil pump, all the good stuff;

thanks
Tadashi

[kenikh]

Originally Posted by parts4porsche

I don´t know if I asked you before Henry, but why not, 70.4 stroke with 102mm pistons on 993 case? that would make same bore/stroke ratio as the 2.8SS we can have all the benefitt of the 2.8 plus we can have twin plug for free.

I have all the parts to build it, to my twin turbo engine. Ti rods from Pankl, turbo oil pump, or GT-3 oil pump, all the good stuff;

thanks
Tadashi

Rod length

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[kenikh]

Originally Posted by parts4porsche

I don´t know if I asked you before Henry, but why not, 70.4 stroke with 102mm pistons on 993 case? that would make same bore/stroke ratio as the 2.8SS we can have all the benefitt of the 2.8 plus we can have twin plug for free.

I have all the parts to build it, to my twin turbo engine. Ti rods from Pankl, turbo oil pump, or GT-3 oil pump, all the good stuff;

thanks
Tadashi

Rod length.

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[al lkosmal]

Just read thru most of this old thread......one of the best threads ever and worth revisiting again & again.

[kenikh]

Originally Posted by al lkosmal

Just read thru most of this old thread......one of the best threads ever and worth revisiting again & again.

Agreed!

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[safe]

Talked to an engine builder last week that went the other way. Custom designed 85mm crank, 102mm cylinders for a turbocharged 4.2 liter engine.... Not sure how he got the crank to fit in there...

[kenikh]

Probably used Honda bearings, to start.

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[Turbo_pro]

I found this old thread and thought it was worth another look.

[jm993rs]

very nice engine !!!

[jm993rs]

I'm loved with this thread !!!

Please the gurus of this engines .....

I'm thinking one 2.7 engine....because i have one crankshaft from engine 2.0..... I'm thinking make the conversion to short steoke !!!

Please give me ideas and view points for mount on my conversion to 914 6 GT thinking for make rally car

Thanks in advanced

[Henry Schmidt]

Originally Posted by jm993rs

I'm loved with this thread !!!

Please the gurus of this engines .....

I'm thinking one 2.7 engine....because i have one crankshaft from engine 2.0..... I'm thinking make the conversion to short steoke !!!

Please give me ideas and view points for mount on my conversion to 914 6 GT thinking for make rally car

Thanks in advanced

914/6GT 7200 rpm
2.5 liter twin plug. 66X90 (short stroke 2.6- 66x92 is also cool)

DC 43 camshafts
Oil Pump upgrade
Crank shaft 2.2
Supertec Head studs
Aasco valve springs and retainers
Clevite rod bearings
2.2 connecting rods ARP rods bolts
Gasket set Viton (Wrightwood Racing)
12 spark plugs ngk-bkr6-ekub 46 mm PMO or Webers
6 PMO 34 mm venturis
6 PMO main jets 130
6 PMO idle jets 55

Venti port 36mm
Machine piston dome & massage transition ridge (compression adjustment) 10.0:1
Valve job & surface heads
Machine valve covers twin plug
Case Savers and 8mm stud inserts
Replace studs & surface gasket surfaces (heads)
Rebuild, convert to ARP and balance 2.2 connecting rods

[Walt Fricke]

Henry - is that an oil shedding coating on those rods? And you balanced the rods after the coating? Or was that a second balance for those which changed a bit?

While you are sharing some of your specs, what cam or cams do you suggest for a SS 2.8, twin plug, EFI, ~11:1 CR, 3.2 heads, oversized valves.