Porsche engine in Speedster out of Rpm

[NicoH]

I am the owner of a Porsche Speedster replica, Kit Car Centre, South Africa. I bought a genuine Porsche engine for it from Aucor a couple of years ago.
The engine seems to have been used for military purposes, maybe a standby lighting plant or something similar. It had a small carburettor on and a thick (heavy) flywheel.

I then fitted a lighter ((beetle) flywheel and two 40 downdraught Weber carburettors. The problem I have is that the engine seems to “run out of breath: at 4,000rpm.
At the George car show in February two owners of very nice beetles told me that it could be one of two things:

1) The standard fuel pump does not supply enough petrol to the carbs. I fitted a high pressure pump which did not improve the problem.
2) The camshaft and possibly the valves is smaller because it is an industrial engine.
NOW, my question:

Should I start with only changing the camshaft to higher lift spec and/or also change the valves?
Is it advisable to split the engine. Will this not lead to a lot of other problems, i.e. line-boring, etc.
Will it be worthwhile? Did the old porsche engines not only rev to 4,000?

I hope you can help me.
I also am looking for anybody that can help me with scraping papers on such build as I started of without papers on my built

Regards,
Nico Human
082 510 4652

[Golfmad]

I dont know much about porsche engines, but my 1960 KG had a normal 1600 TP beetle engine, and it revved to 5500 with the standard carb no problem, but you could feel there were no more power after 5000.

[louisvr45]

Golfmad , did it came with a single solex 34 pic 3 carb? or a twin carb setup?

[Golfmad]

It had a standard solex carb. But it did have 14" deep dish steel wheels with low profile tyres, so I suspect thats why it revved up so easily.

[slak]

i think u have a porsche industrial motor and it doesn't rev over 4000RPM
because it didn't need to in it's previous job
don't know much about them though
have u checked if the timing advances like it should on a normal motor
cause for a stationary motor the timing doesn't need to change as it revs at constant revs
day in and day out i would start there

Welcome to ACVWSA

[s-thang]

Hi
I can confirm that the industrial engines do not perform like the normal ones.
harry lombaard has an industrial engine in his 356 (origional) and it simply is not a revving engine...
cool

[arnocill]

For a genset the motor would be tuned for optimal power at 1500 rpm to give a 50hz output.
My guess is that they use different camshaft, cylinder heads, and dizzy without advance like slak said.

[Bugger]

My personal experience with the industrial motors was the 127 engine numberd type 4 1800 motors

It also had a tiny carb with beetle twinport lookalike intake manifolds on

In the beginning everyone said it will not work in a Bus as it was built for industrial use


I prooven them all wrong as I fitted them to more than 10 Bay window busses with the Bus original tinware and carbs and dizzy and they ran Beautiful
even with the Restrictive industrial Silencer
Beetlefanatic on the forum had a bus with one in and think he did more than 60K before he sold the bus with out any problems

I have striped one of them that I sold Jason on the forum aswell that he want to use in Aero use
This was my Opportunity to investigate
All the internals was Exactly the same as a 1800 Bus motor that came off the Factory line
I still got the cam and I will get it Degreed one day to be able to know the profile it had

The Porsche ones I have seen Run like hell aswell with Carbs and Electronic ignition systems
There are also all the roumors of cam and valve diferances I dont think the factories would have gone in to so much trouble
But then again the Porsche ones might have been Built specificaly for the industry


If you want to open the motor it is not to say you have to alighn bore because you opend it

If all clerances etc is still right why spend unnessesary money

If you need help doing it We will be able to strip and assemble the motor for you
My Partner has 25Yrs Engine building experience

[IMPI]

There are lots of internal differences between industrial Porsche engines and std car engine not like what Pierre suggests for VW industrial engines which were identical to their car counterparts.
Differences being the following.
Larger bottom crank pully to supply cooling air at 3500rpm max mor revs will explode the fan or cause cavitation and less cooling
Non counterwighted crank which was designed for low RPM operation
Cam which was optimised for low rev range Approx 50 hp versus 90 for the otherwise same engine in 356)
Single carb some did not even have an Accelerator pump.
heavy flywheels
The engine has nice torque but is almost the same effect as putting a std type4 two liter in a bug lots of torque low down but it peters out at 4000 rpm.

Bear in mind that the 356 engine is basically a souped up early beetle 36 horse engine and all parts are modified to reach the power that were reached back in the day.

You can possibly get away with changing only the cam and lifters but that non counterweighted crank will destroy the engine if the revs are used.
Armand

[vader]

Was there no governer fitted to these motors?

[NicoH]

Thanx Guys

Wil mail my Dad with your answers and get back to you, I do the blogging for him

Regards
Neil Human

[Bugger]

Was there no governer fitted to these motors?

Yip there was but you remove it when fitting other carburation to the motor

[louisvr45]

Larger bottom crank pully to supply cooling air at 3500rpm max mor revs will explode the fan or cause cavitation and less cooling

Is this on the early 25 & 36hp engines?
Up to what reves is it save without destroying the fan?

Non counterwighted crank which was designed for low RPM operation
Cam which was optimised for low rev range Approx 50 hp versus 90 for the otherwise same engine in 356)
Single carb some did not even have an Accelerator pump.

Does the solex 34 pic 4 have one?

[62vwbeetle]

Hi nico, if its an industrial you have to

1 immediately change cam, can get used from Carrera in JHB or new off Internet .
2. Heads need lots of work, bigger valves etc etc
3. Put a hop up 1800 kit on it

Then you good to go, should run 90 mph plus and pull up any hill. It's about a 30 k job if you know a good porsche person , if not it gonna be a lot more