Early 1969-1972 911 which one for race

[racecar866]

Ive decided to build an early 70's 911 to race in SCCA ITS. Can anyone help in my search for the correct car. As you know they come in three diff motors 2.0, 2.2, 2.4. Also some are injected some carbs, trannys are all different. What I need to know is which model has the greatest potential of making the most HP? According to the rules the larger the displ. the more the min weight will me, by the way the "S" is NOT allowed. We can up the CR ratio .5 , balance, headers etc.....no cheater cams and not stroking. And who builded quality, race motors, reasonable price , good turnaround times. Any one who races an early car 69-72 Id like to hear your input and advice. Thanks

[Bill Verburg]

'69 -'71 used the 901 trans, its lighter and has a more desireable for racing shift pattern, the '72 has a 915 a little heavier and a more robust w/ a bigger stronger clutch. Each trans has it's adhereants.

The '72 was the first year of the smog motors, more displacement 2.4 liters vs earlier 2.2 and 2.0 liter engines. The earlier engines also had more compression than the '72s.

If an S isn't allowed I might look for a 2.2 liter '70 -71 E w/ a stripped out interior and 901 trans.

[Dantilla]

Can you build a 2.0 car to fit both ITS and vintage?

[ErVikingo]

Word of advice, start by looking at the General Competition Rules of the group/sanctionng body you plan to race with...

[boxster03]

you might consider buying one already set up if you are not into the whole building it thing with a race log, that way you are assured a spot on the tarmack

[donstevens]

Originally posted by racecar866
And who builded quality, race motors, reasonable price , good turnaround times.

There is no such thing as a reasonably priced quality 911 race engine that you can get quickly.

I had a guy tell me one time that """You can have any two but you can't have all three. If it's fast and good, it aint gonna be cheap. If it's good and cheap it aint gonna be fast. Finally, if it's fast and cheap, it aint gonna be no f*cking good"""

A 2.4 E configuration will be the fastest of the options you mentioned. But "it aint gonna be cheap"

If you find a way to make a 911 ITS legal, it will be Vintage legal.

Don

[Grady Clay]

I just read the SCCA GCR ITS rules and it looks like a ’70-’71 911E is a good choice. Don is correct, it will be expensive to do it right but that is the only way to be safe and successful.

Feel free to e-mail me and I’ll help you with a plan. I’m pretty good at reading the GCR and organizing this kind of effort.

Best,
Grady
gradyclay@hotmail.com

[ErVikingo]

FYI, a fast 2 liter engine can run you upwards of $30K... It will not be legal at SCCA but legal at PCA, HSR, CHRA, ...

[Plavan]

WOW $30K for a 2.0L motor!!! Those Klub sport guys are crazy out East.
My whole 2.5L race motor with new PMO 46mm ($3000 of the total)), 10.5 J&E's, Cams, ect... cost $9000 with LABOR! That does not count the Alum case cuz I already had it along with racing springs and Ti retainers... 220 HP at the wheels on the Dyno and still without a drop of oil. AASE motors knows how to put them together, and not bend you over....
I have all the trick parts in mine..... What the heck do they charge for labor? There is NO WAY anyone would pay that out West.

I can't imagine a $30k 2.0L motor..... somebody's pocket is getting mugged and they have no clue.

I will build anyone a $60k 2.0L motor....any takers???? it cost's twice as much so it MUST be faster.

[jluetjen]

Originally posted by ErVikingo
FYI, a fast 2 liter engine can run you upwards of $30K... It will not be legal at SCCA but legal at PCA, HSR, CHRA, ...

ErViking -- that kind of defeats the purpose of the original question. He doesn't want a PCA, HSR or CHRA motor, he wants an SCCA ITS motor. Personally I think that a well put together stock spec. 2.2E motor should be fine for IT. For not much more you can get the P&C's to spec with an additional .5 CR, and an the additional 1mm overbore. Don't waste your money doing more since it isn't legal!

you might consider buying one already set up if you are not into the whole building it thing with a race log, that way you are assured a spot on the tarmack

The problem is that 911's are not raced in IT very often. I'm only heard of one or two so far. So it might be a long wait. The other problem with this within the context of 911's is that most of the track ready 911's out there are built as hot rods without consideration of any rule books, let alone the SCCA GCR. So if you start down this approach you need to be sure of such things as...
1) The cage meets the SCCA specs, both the minimum and in the case of ITS, maximum in regards to the number of mounting mounts.
2) The engine is ITS legal. You know the rules, no wild cams, 10.5:1 CR, twin plugs or stuff like that.
3) The interior isn't over-stripped.

Otherwise you'll just waste a lot of time, money and effort undoing what the previous owners have done. To be honest, building an IT car is not that difficult. I/ve built an ITB car that I raced in the past. The big lesson that I took away from that is to not try to be greedy with the ignition timing -- and melt a piston. Set it to spec or use a dyno to set it up and then focus on your driving. Not the motor.


BTW, Have you found the IT Forum site?

[ErVikingo]

I agree John, just commenting to put in perspective how crazy it gets. I assume that he'll get the itch to do vintage racing and find that an IT spec engine is way underpowered for that. My bad

Chad,

A Klub sport (FIA) spec engine is much lower than that but a high output top running 2 liter (I'm afraid) runs up there turnkey everything included (intake/exhaust/ignition). I know its a bunch .........

The unofficial quotes I've gotten from west coasters are similar...

[donstevens]

Originally posted by Plavan
There is NO WAY anyone would pay that out West.

I can't imagine a $30k 2.0L motor..... somebody's pocket is getting mugged and they have no clue.

One of the hottest 2.0L engine builders in HSR is a west coast guy and his engines are up in that range. It is crazy but many of the guys up frnt are spending that kind of money. To top it off, the engines need to be freshened every 20 hours or so.

Don

[Plavan]

Thats Frank Beck (West Coast Guy). He can drive too!

[ErVikingo]

Chad, you got mail....

[racecar866]

Thanks for the many replies on my original post here. Not to put any of you down, but I've been racing and building cars for years. I dont need a lesson on the rules or pitfalls of building cars. What I do need is inside information from people that actaully own early 70's 911's, their actual HP numbers from building motors. How do the FI cars stack up against the carb cars. IS the 2.0 a dog motor? Can the 2.2 make as much power at the 2.4, That sort of thing......get what I mean??? I know its big $$$$$$, thats not my issue, but in every car line, there is 1 or 2 guys, that work in some little shop, that actully give good service and dont over-charge, thats what Im asking???? I dont need to here stuff like "there's no such thing" or "well if you raced it in XXXX class" Im talking about SCCA ITS, the rules are .05 up comp, 1mm over bore, headers, balancing, thats about it. So if anyone can help or offer me some good advice, or offer some good names in the business id like to hear from you. Thanks so much.

[ErVikingo]

To recommend a shop we must know which coast/area you are on?

FI/Carbs: FI power is always there vs carbs that sometimes need some good/gentle foot action. FI just step on it and it "adjusts itself". Carbs are easier to setup initially but harder to maintain whereas MFI is the opposite. MFI is an art that is getting lost so finding a good shop is not easy.

2.0 are not dogs by any means but I'd go as large as the category allows.

[Grady Clay]

Russ,

Here are the 2.2 and 2.4 power and torque for comparison.
The 911E-C is the 2.2. The 2.2 is 2195 cc, 9,1:1 Compression
Ratio (CR). The 2.4 is 2341 cc, 8.0:1 CR.
"
"
© Dr. Ing. h.c. F. Porsche A.G.
"
"
© Dr. Ing. h.c. F. Porsche A.G.

With the SCCA allowances the 2.2 goes from 2195.4 cc to
2247.1 cc, an increase of 2.4%. The CR goes from 9.1:1
to 9.6:1 an increase of 5.5%.

The 2.4 goes from 2340.8 cc to 2396.9 cc, an increase of
2.4%. The CR goes from 8.0:1 to 8.5:1, an increase of 6.3%.

SCCA specs the ITS weights at 2485# for the 2.2 and 2585#
for the 2.4, an increase of 4.0%.

Porsche specs the 2.2 peak power at 155 hp and the 2.4 peak
power at 165 hp, an increase of 6.5%. The two power curves
show the power at 4000 rpm for the 2.2 is about 104 hp and
the power at 4000 rpm for the 2.4 is about 111 hp, an increase
of about 6.8%.

I am a proponent of “lighter is better. In this case the additional
100# is probably a wash and you can remove weight from places
like the rear window and gasket and put it low and forward on
the passenger floor.

The 911E has very adequate brakes so I don’t then the
additional 100# will add too much stress there.

The biggest difference is the 0.5 point in CR will do far more
to “wake up” an engine at 8.0:1 CR than it will for one at
9.1:1 CR.

The 2.2 and 2.4 came with the same cylinders (not pistons)
and the same heads including valves. An important
difference between the 2.2 and 2.4 is the crankcase.
The 2.4 came with the considerably stronger 7R case

The fact that the Type 915 transmission of the 2.4 is heaver
than the Type 911 of the 2.2 probably makes little difference
because it is close to the car’s Center of Gravity (CG). The
shifting pattern is a matter of personal choice although I
prefer the Type 911. The 915 is a much more robust
transmission. Some ’72-‘73 915 were specified from Porsche
with an internal oil pump and it could be successfully argued
to include that.

OK, on to gear ratios:
All these transmissions use a 7:31 Ring & pinion gear ratio.

The “standard” gears for the Type 911 are:
1st = 11:34 = 3.091 (A)
2nd = 18:32 = 1.778 (GA)
3rd = 23:28 = 1.217 (O)
4th = 27:25 = 0.926 (V)
5th = 29:22 = 0.759 (ZA)

Here are these gears.
"
"
© Dr. Ing. h.c. F. Porsche A.G.

The “standard gears for the Type 915 are:
1st = 11:35 = 3.181
2nd = 18:33 = 1.833
3rd = 23:29 = 1.261
4th = 26:25 = 0.962
5th = 29:22 = 0.759

Here is the chart for the Type 915.
"
"
© Dr. Ing. h.c. F. Porsche A.G.

As you can see, neither of these match the ratios specified in
the ITCS. SCCA has specified gear ratios for both the 2.2 and
the 2.4 as a Type 911 with ratios:
1st = 11:34 = 3.091 (A)
2nd = 18:34 = 1.89 (F)
3rd = 22:29 = 1.32 (M)
4th = 25:26 = 1.04 (S)
5th = 29:23 = 0.79 (ZA)

These are the ratios from a ’69 911 (T, E & S).
Here is that chart.
"
"
© Dr. Ing. h.c. F. Porsche A.G.

The Type 911 and Type 915 are directly interchangeable using
different clutch cables, throwout bearings and shifters. Both
use the same ZF Limited Slip Differential (LSD) or solid “spool”.

I suppose you have the choice to use the standard Porsche
ratios and type for the 2.2 or 2.4 or use what SCCA specified.
I suspect there will be a “clarification” in Sports Car
Fastrack News at some point.


Reading ITCS 17.1.4.C shows much will depend on documenting
the non-availability of certain parts and the necessity to used
other (improved) versions. This Forum can help.

Scanning the ITCS some things come to mind:

ITCS 17.1.4.D.1.b; does this language allow you to move the
fuel filter from high and in the rear to low and in the front (in
the smuggler’s box)? Clearly you can move the fuel pump
from the standard ’71-’73 rear location to the ’70 placement
on the front crossmember.

ITCS 17.1.4.D.1.g; I would leave the provision for being able
to re-install heat exchangers for the situation where you
must race in the cold and rain. Defrosters are invaluable.

ITCS 17.1.4.D.1.h; Clearly you want to use an Accusump.
Does the language allow a larger oil sump tank with baffles?
Can the “lines” include the 993 ball check valve in the
breather? I would opt for running the oil lines through the
cockpit and trunk. Lines along the rocker panel are susceptible
to damage from an errant contact with a hay bale or the like.

ITCS 17.1.4.D.1.i; I’m in favor of a very large but ightweight
(2 gal) catch tank that is easy to drain. One of the “tricks”
to keeping an engine from getting air in the pressure pump
intake is to over fill the tank when cold. It will put a quart
ot two in the catch tank on the cool-off lap. A breather hose
from one intake valve cover to the other will allow the oil in
the cam boxes to return to the sump faster after a sustained
long corner.

ITCS 17.1.4.D.1.j; Does this language mean you can substitute
a “slipper skirt” forged piston for the OE cast 911E piston?
Clearly you must use the Biral aluminum-iron cylinders but
along with the overbore you can taper the cylinder for less
clearance at the top.

ITCS 17.1.4.D.1.l; You will find that a builder will combine
this 0.025” head limit with the wrist pin bushing tolerance
and the cylinder shim to get the best “squish” and not
exceed the CR limit.

ITCS 17.1.4.D.1.n; This allows you to use the “Turbo” fan
with the 84 mm (or 80 mm depending…) to turn the fan
faster. Unfortunately they disallow changing the crank
pulley. Careful fan belt selection will help. These engines
are head temperature limited (even at 8.5:1 CR). Anything
you can do to improve the cooling of the cylinder and head
will allow more power (even considering the increase loss
from turning the fan faster.)

I have some errands to run. I’ll work our way through
the ITCS more.

Best,
Grady

[Grady Clay]

Russ,

I’m going to stick my neck out and not recommend the 2.0.
The '68-’69 will have the weakest crankcase, no bearing
for the jack shaft, a smaller clutch, and a less desirable
combustion chamber shape. The benefit is 100# lighter
than the 2.2 and 200# lighter than the 2.4.

Here is the engine performance for the Type 2000, the
carbureted version of the 911E. it is rated at 130 hp
at 6100 rpm and 17.8 mkp at 4200 rpm.
"
"
© Dr. Ing. h.c. F. Porsche A.G.
Here is the engine performance for the MFI 2.0 911E. It
is rated at 140 hp at 6500 rpm and 17.8 mkp at 4500 rpm.
"
"
© Christophorus #78, December 1968, Dr. Ing. h.c. F. Porsche A.G.

The two 2.0 engines are virtually identical other than induction
system and valve size. The ’68 and earlier had 39 mm intake
and 35 mm exhaust. The ’69 911E had 42 mm intake and
38 mm exhaust. The 2.2 and 2.4 had 46 mm intake and 40 mm
exhaust. Both 2.0 engines are specified with 30° ignition
advance at 6000 rpm except the ’68 911 USA was 32° at
6000 rpm under full load (vacuum retard not having effect.)

The MFI engines weigh a little more than the carbureted
version because of the MFI pump and associated plumbing
and hardware.

Some other important differences among engines are the
connecting rods were strengthened with the 2.2 compared
to the 2.0. For crankcase windage it is desirable (in this
case) to use the 2.0/2.2 911T cast steel, non-counterweight
crankshaft. That is ITS legal because the T & E are listed on
the same line for the 2.0 and 2.2. There isn’t a non-
counterweight crankshaft for the 2.4.

It may be possible to argue that the magnesium 2.0 and 2.2
crankcases are NLA and the suitable replacement is the 7R
2.4 case. A 7R is a tiny bit heavier and not as good windage
but much stronger and able to hold tolerances better –
something desirable when you are near the CR limit.


As a general construction principal, I would get all the
undercoat/sound deadening material off the rear and
top parts of the 911. Do everything legally possible at
the rear of the 911 to get rid of weight. Get it as light
as consistent with the rules and then ballast to minimum
weight.

If the goal is to win the Runoffs, you must be able to
support every little thing with documentation. I can
see a 100# file of workshop manuals, parts manuals
and correspondence documenting parts and availability.

Your competition is likely to be the early Miata with the
normal Mazdaspeed suspension. Of course 240-300Z
are no slouches. Who knows, a well prepared Honda
Del Sol at 2175# (1590 cc) might give everyone a run
for their money. All in all, a well prepared 911, good
driving and the exact right tires every time can certainly
win.

Best,
Grady

[jluetjen]

Originally posted by racecar866
Thanks for the many replies on my original post here. Not to put any of you down, but I've been racing and building cars for years.

Well Gee! Why didn't you say so. Given the wide range of experiences on this BBS, questions and responses come in from experts (like Grady and Henry Schmidt) to teenage dreamers. When in doubt most responses will be aimed at the novice level.

I dont need a lesson on the rules or pitfalls of building cars. What I do need is inside information from people that actaully own early 70's 911's,

OK. Check the signatures on the respones and you'll know.

their actual HP numbers from building motors. How do the FI cars stack up against the carb cars.

Generally, my rule of thumb is that the MFI'd engines make about 10 HP more then then carb'd motors. Some may disagree. Carb motors have fine throttle response, but MFI'd motors have awsome throttle response. MFI is basically the same system that was used on the Porsche 906, 910, 907, 908 and 917 race cars in the 60's and 70's.

IS the 2.0 a dog motor?

No. Absolutely not.

Can the 2.2 make as much power at the 2.4,

No again. Generally, the S's are in similar state of tune, the E's are all similar. In the case of the T's there are differences. The big difference is that the bigger engines make proportionally more torque then the smaller engines that you'll be able to use across the rev range. I believe from my own analysis that the 2.4 E's are somewhat port constrained compared to the 2.2E's, but it's pretty subtle.

That sort of thing......get what I mean??? I know its big $$$$$$, thats not my issue, but in every car line, there is 1 or 2 guys, that work in some little shop, that actully give good service and dont over-charge, thats what Im asking???? I dont need to here stuff like "there's no such thing" or "well if you raced it in XXXX class" Im talking about SCCA ITS, the rules are .05 up comp, 1mm over bore, headers, balancing, thats about it. So if anyone can help or offer me some good advice, or offer some good names in the business id like to hear from you. Thanks so much.

Grady's post says it all, and his credentials speak for themselves having SCCA and Porsche race experience dating back to the '60's, with some IMSA and other stuff thrown in. He's got a good understanding of the rule book with the exception of replacing the window glass, which is forbidden in IT the last time that I checked.

Personally, I'd go for a 2.2E for the following reasons:
1) It's got MFI.
2) It's got a healthy step up in power from the 2.0E (which I own.)
3) Due to the drop in CR and the port flow issue, the 2.4E doesn't get quite a proportional increase in HP over the 2.2, but you have to lug around more weight. But the 2.4 engine is more flexible, but I don't think that you'll be spending much time in the lower rev ranges where that matters.
4) Personally, I prefer the 911 style shift pattern. If you are racing the 915, you'll need to go across the gate in the 2/3 and 4/5 shift. With a 911 box you'll only need to go across the gate during the 3/4 shift, but my experience is that it is still a fast shift.

BTW, your primary competition at the front of the pack will be BWM 325's and later model RX7's, with some Z-cars thrown in depending on the region that you're in. BTW, what part of the country are you in?

That's my $0.02 based on my few years of ITB experience, and the past 6+ years of early 911 ownership.

[Grady Clay]

Bill, lame ‘ol me didn’t proof my comments - as I usually do.

OK, back to the task.

17.1.4.D.3.b – Does this language allow you to have two fender mounted front coolers? It would be desirable to have front coolers in each front fender with electric fans. They should be in parallel and flexibly mounted to withstand impact damage without leaking. It appears that the oil lines are allowed to pierce the body/chassis but not the air ducting. Of the three lines, only ’68 doesn’t have the battery boxes in the way of good oil coolers.

17.1.4.D.3.d – When you use a 911SC thermostat, locate it at the engine with a short path from the engine scavenge out to the thermostat/pressure relief to the oil sump tank. This will reduce the instances where the pressure relief opens.

17.1.4.D.3.f – When using screen, make it zigzag (about ½” peak-to-peak) for strength. Its function is to protect the cooler from stones. The zigzag makes it stronger and more resistant to stones.

17.1.4.D.4.a – allows you to use the OE open differential, the usual ZF LSD, a gear type differential or a spool. For track only use, I prefer the spool.

17.1.4.D.5.b – This is where you can make the mist significant gains of everything in the rules. The combination of spring rate, shock rate, suspension position and alignment will win races. If you intend to win the Runoffs, race at Mid-O every chance you can. Some extended test sessions in between will help. Racing at other tracks get you invited and force you to not develop single-track bad habits.

You need to be able to adjust the suspension by swapping components among different torsion bars, shocks, sway bars, tires and alignment settings. As your familiarity with the car and track change, you need to be able to predict what set-up you need for particular track conditions. As you know central Ohio can have summer conditions, rain, snow and about anything else you can think of.

Best,
Grady