Help on engine type 901/07

[AlexJ]

Hi all,

I found an engine for sale which information is:

901/07 11701

3180143

I would like to know engine specs because I have been finding some confusing information around the internet...

As I am building a T/R rally replica based on a 68T and would like to know if engine type 901/07 offers a better potential to achieve an S performance on a 2.0 liter engine. I know already that it will cost a fortune to upgrade a 2.0 T in order to get the S numbers...

Would a 901/07 be a more effective (cheapest) alternative?

[Grady Clay]

Alex,

The answer is “probably”.
3180143, 901/07, 11701 is very early in the 1968 911L RoW production. It “probably” has an aluminum 901 crankcase. The transition to magnesium was (supposedly) with 3180182.

What engine is with your ‘68T? Original was a 901/03. These transitioned from aluminum to magnesium with 2080618.

The ‘List’ of engines: Type 901/xx Engine Build #'s fits your numbers.


The aluminum 901 case is quite a bit stronger than the first generation (or almost any) magnesium crankcase.
That said, it will still need some attention to bring it to race standards.

The 901/07 will have a forged & counterweighted crankshaft, better connecting rods, Biral cylinders, better valves, dual valve springs and probably better rocker arms compared to a 901/03. The 901/07 is a ‘fine’ early engine. The 901/03 is a ‘cost-reduced’ type.

Best,
Grady

[AlexJ]

Hi Grady! Always a pleasure to meet you here!

Yes my T engine is:
Engine number: 2080297 type 901/03 10537

The 901/07 is 130 hp, right?

[AlexJ]

I am just asking this, in case this engine could be a cost effective alternative to an S engine which is becoming difficult to find and when you find it... $$$$

[Grady Clay]

Alex,

Yes, this is absolutely a cost effective alternative to an S engine.
In fact it may be a ‘better’ solution in that race engines must be “disposable”.
You use them up racing (hopefully only after a long and successful career), rebuild and use for Sunday 'show' driving.


Yes, 130 hp @ 6100 rpm. This has ‘E’ cams. For your rally use, this can be more suitable (flexible) than an S-cam engine.
You will find that with headers and a bit larger (from 30 mm to 31-32 mm) venturi, it may be faster than an ‘S’ in this situation.
This will particularly be true if you are class-restricted to standard AFMSX gearing.
With a proper rebuild, it can be safe above 7000 rpm, adding to the flexibility of driving.
In this situation, an E-cam race engine may have more “area-under-the-curve” than an equivalent S-cam engine.
Besides, you can swap to S cams anytime. They will work acceptably well with the 901/07 heads and the correct valve clearance pistons.

Does the class allow 1.0 mm overbore?
If so, you can use the 80 mm Biral cylinders from the 901/07 and have proper clearance 81 mm racing (light-weight, high compression) pistons fitted.


Before we get talking more about engine mods, what are the exact links to the complete, current FIA Regulations for your events, class and situation?
All I have is a photocopy Appendix J, Article 253-2011; about safety equipment.
Is this Historic Rally Championship appropriate for your events?
What are the (pdf) links for your car and engine?

EDIT
So … your ‘68T engine 2080297, 901/03, 10537 has the aluminum crankcase? Yes?

Best,
Grady

[djpateman]

Originally Posted by Grady Clay

EDIT
So … your ‘68T engine 2080297, 901/03, 10537 has the aluminum crankcase? Yes?

Almost every normal build under 12000 should be aluminum, so 10537 & 11701 will be aluminum (I am 99.99% certain); I know of only one magnesium case, and it was an experimental engine with a non standard serial.

[Grady Clay]

Originally Posted by djpateman

Almost every normal build under 12000 should be aluminum, so 10537 & 11701 will be aluminum (I am 99.99% certain); I know of only one magnesium case, and it was an experimental engine with a non standard serial.

GOOD.
Alex, that will give you TWO (hopefully good) aluminum 901 engines.

From: FIA, The list of ”Previously Homologated Cars“ are:

Hom.; Grp; Make; Model; x; Total Cyl. displacement; Hom. Date (d/m/y); ASN country; Ext; Observations.

249; 4; Porsche; 910; 1991; ; 01.01.1969; D; 0.
Decodes as:
249 = FIA Homologation number.
4 = Group 4.
Porsche = Manufacturer.
910 = Model 910.
1991 = Total displacement in cc.
Space for “x”. Whatever “x” is.
01.01.1969 = Homologation date (day.month.year).
D = Deutschland, country of origin.
0 = ?
There is space for ‘Observations’.


183 GT Porsche 911 1991 16.11.1964 D 3
1451 2 Porsche 911 1991 01.01.1966 D 2
503 3 Porsche 911 1991 01.01.1966 D 1
3060 3 Porsche 911 2687 01.02.1974 D 2
204 GT Porsche 912 1582 01.08.1965 D 2
502 3 Porsche 912 1582 01.01.1966 D 0
5139 1 Porsche 912 1582 01.01.1967 D 1
606 3 Porsche 912 1582 01.01.1969 D 0
3003 3 Porsche 912 1582 01.01.1970 D 2 old Gr. 1 form 5139
250 4 Porsche 917 4494 01.05.1969 D 2
3075 3 Porsche 924 1984 01.01.1977 D 6
3075 B Porsche 924 1984 01.01.1977 D 4 Tr
3081 3 Porsche 928 4474 01.01.1978 D 1
3081 B Porsche 928 4474 01.01.1978 D 0 Tr
21 GT Porsche 356 B / 1600 GS 1588 16.06.1960 D 1
71 GT Porsche 356 B / 2000 GS 1966 08.10.1962 D 3
139 GT Porsche 356 C / 1600 SC 1582 05.09.1963 D 0
501 3 Porsche 356 C / 1600 SC 1582 01.01.1966 D 0
159 GT Porsche 904 GTS 1966 12.04.1964 D 4
282 B Porsche 911 Carrera 3164 01.06.1986 D 2
295 B Porsche 911 Carrera 2 3600 01.09.1990 D 3
294 B Porsche 911 Carrera 4 3600 01.09.1990 D 2
609 3 Porsche 911 E 1991 01.01.1969 D 2
3011 3 Porsche 911 E/T (2195 & 2341) 2195 01.04.1970 D 4 Cylinder capa.
579 3 Porsche 911 L Targa 1991 01.01.1968 D 1
547 3 Porsche 911 S 1991 01.11.1966 D 6
608 3 Porsche 911 S 1991 01.01.1969 D 3
3005 3 Porsche 911 S 2195 01.01.1970 D 0
3061 3 Porsche 911 S 2687 01.02.1974 D 3
3025 3 Porsche 911 S ( 2195 et 2341) 2195 01.04.1970 D 8
578 3 Porsche 911 S Targa 1991 01.01.1968 D 1
3062 3 Porsche 911 SC 2687 01.02.1974 D 10
3062 B Porsche 911 SC 2687 01.02.1974 D 3 Tr
207 B Porsche 911 SC 2687 01.03.1982 D 11 ON 3062
577 3 Porsche 911 T 1991 01.01.1968 D 4
607 3 Porsche 911 T 1991 01.01.1969 D 3
645 4 Porsche 911 Turbo ( 2993) 1.4 4190 01.01.1976 D 0
3076 3 Porsche 911 Turbo ( 2993) 1.4 4190 01.01.1977 D 8
3076 B Porsche 911 Turbo ( 2993) 1.4 4190 01.01.1977 D 2 Tr
208 B Porsche 911 Turbo ( 2993) 1.4 4190 01.03.1982 D 10 ON 3076
298 B Porsche 911 Turbo 2 (3299) 1.7 5608 01.04.1993 D 0
296 B Porsche 912 Carrera RS 3600 01.03.1992 D 3
580 3 Porsche 912 Targa 1582 01.01.1968 D 0
626 4 Porsche 914 / 6 1991 01.03.1970 D 3
3042 3 Porsche 914 / 6 1991 01.10.1971 D 2 BR
672 4 Porsche 924 Carrera GT ( 1984) 1.4 2777 01.01.1981 D 4
203 B Porsche 924 Carrera GT (1984) 1.4 2777 01.01.1982 D 8 ON 672
660 4 Porsche 924 Turbo 2777 01.02.1979 D 1
3083 B Porsche 924 Turbo ( 1995) 1.4 2793 01.04.1979 D 3 Tr
3083 3 Porsche 924 Turbo (1984) 1.4 2778 01.04.1979 D 4
3085 3 Porsche 928 S 4664 01.11.1980 D 1
3085 B Porsche 928 S 4664 01.11.1980 D 0 Tr
209 B Porsche 928 S 4664 01.03.1982 D 4 ON 3085
283 B Porsche 928S 4597 01.06.1986 D 2
284 B Porsche 944 Turbo (2479) 1.4 3470 01.06.1986 D 3
226 4 Porsche Carrera 6 1991 01.05.1966 D 0
637 4 Porsche Carrera RS 2687 01.01.1973 D 5
3053 3 Porsche Carrera RS 2687 01.07.1973 D 18

I think that Alex’s ’68 911T may be in this #577 homologation group:
577 3 Porsche 911 T 1991 01.01.1968 D 4

After browsing the FIA site, dumb ol‘ impaired me still can’t find #577.
I’m inspired me to look to make sure the Homologation number doesn’t specify a specific Porsche engine type.
If it does, there must be a later ‘rules waiver’ to open up for ‘similar’ engine types.


Alex, exactly what current group and class are you intending? (“B4”?)
Talk to your future competitors and other (professional) builders and discuss how the rules are interpreted.
Certainly we must have some FIA Historic racers and car/engine builders on the Forum.
This might be a good time to document how to build (or bring into spec) a competitive FIA-legal car and engine.
Alex’s 2-liter 911 is the perfect example. There are a LOT of these around.


FYI, here is the complete, original ”Appendix J“ pdf.

Best,
Grady

[AlexJ]

Hi Grady,

As I am building a T/R replica, this will suit the 577 homologation form.

This will allow the lightweight T chassis on S specs engine or E.

For example, all the tolerances on the heads are maximum S sizes.

Gearing has to be with the known (factory) ratios.

Yes, 1 mm overbore is allowed.

Basically, everything has to be period correct except for safety devices and other bits - as long as it is homologated.

For example, at the Apendix K it is stated the following:

5. Engine
5.1 Reboring
Allowed to a maximum oversize of 1.2 mm of the original bore,
provided that the increase does not change the period capacity
class of the car.

5.2 Cylinder head and block
The compression ratio may be modified by machining the face of
the block or cylinder head and/or by omitting the gasket or using
a gasket of different thickness.
Only homologated rocker arm assemblies may be used.

5.3 Pistons, camshafts and valve springs
They may be altered, or alternative pistons, camshafts and valve
springs of different specification or manufacture may be used,
provided that the number employed does not exceed that of the
homologated engine.

5.4 Finishing
Machining, polishing and balancing of the engine parts are
authorised, on condition that:

5.4.1 these operations are carried out with no addition of material.

5.4.2 it is always possible to establish unquestionably the origin of
these parts as being series-produced, authorised by these
regulations, and/or homologated.

5.4.3 the dimensions and weights given on the car’s homologation
form are respected, taking into account the tolerances specified
on this form or in period Appendix J. If these tolerances are not
specified on the form, a tolerance of ± 5% may be taken into
account.

6. Oil system
6.1 An oil filter and/or oil cooler, for engine oil only, may be added.

6.2 Oil coolers must be contained within the periphery of the
bodywork as viewed from above.

6.3 Fixed or mobile sump baffles and gates are permitted.

So, a lot can be done...