Engine Build Advice for 71T
 

Hey all - so I have this car, a signal orange 71t, it's a nice 'very mild' hot rod with a stock-ish look and I plan to keep it that way. The car does not have its original engine, a 2.7 from a 77 was swapped back in 1992, and the case is long gone. Have all the receipts too! (wow were prices cheap).

Current engine is pretty fresh, about 5k on the top end, with refreshed rings on the bottom at that time. Engine is just a slight bit weapy, but not leaking/dripping. It starts and runs good. Has Webers on it now.

What I don't like about current setup: I'm not a carb fan (ok love the noise...but that's it), the engine has great torque, but would like it to rev/pull harder in the higher ranges, and feel a bit more "lively".

My goal: a lively, revvy motor, not 'peaky', reliable, can drive it hard, canyons and occasional track/DE/AX, call it around 225HP. I think i would want EFI. I would want all the tweaks that make it robust and reliable. I don't want a car that only runs right on race gas, or is super cold blooded, etc.

I'm curious to the thoughts here. My first reaction is to build the 2.7 to an RS type spec and do a motec/PMO EFI system...

Thoughts? Keep current case/build that? Go source something else?

Would like to not break the bank, but I am willing to spend some $. I'm a driver not a collector/seller. :-)

9.5:1 JE pistons
Mod_S cam
Open the intake ports to match new air flow requirements

Keep the webers or add your EFI/ITB of choice.

Plenty powerful enough for a 71T.

Oh, this one is easy. Buy one of my 3.6 cases and build up a stockish 964 motor. I can get you practically every used part for that motor.

What you'll get is a high torque, easy running modern build that you won't have to screw with and it will out power anything else you could build with a smaller case.

Hahha. Man I’ve been watching your process on rennlist and love what you’re doing. We need to talk when my 964 is ready for a build. That’s next on the list.

For this, I’m really not sure i want to go that big, and then there is the 901 trans....

Well the 901 is a limiting factor for sure. I have a 3.6 and a G50 in my 73, and it's a hoot but it is a properly prepared car with huge brakes and wide rubber.

So build a motor like I have in my 914. It has a 2.7 mag case with a 901. Weber 40, 964 cams, electronic ignition, about 220HP, hauls ass. It's got just about everything you can do to a 2.7

Will a 964 engine work with the stock 71 tranny (901) or would that have to be changed to a stronger 915?

Well... depends how you drive but a 901 with 300+ HP probably is t going to be long loved the way i drive these things :-)

The 901 in my car is fresh and has some strengthing parts from the rebuild. Like the center carrier i don’t know what the part is called.

And i love the dog leg and way it shifts. It’s really nice to drive.

I’ve weber 40 and a pertronix on it now. It runs and drives great. I’ll probably go efi.

Do you mind detailing what you did to your 2.7?

Thanks.

Been a while, but Weber 40s, 964 cams, AASCO valve springs, all new valves, electromotive ignition, headers, JE pistons, I forget what CR, but a little hotter than stock. Single plug.

Oh, and it needed 7500 worth of machine work because the case was warped like a pringles chip which was the impetus to make my own cases.

You’ve got to pick your poison. You won’t get the smaller displacement Porsche engines to rev without making them peaky. Anything over 7k on a 3l or less loses something on the bottom end.

So you need to decide torque in the midrange with displacement like Catorce advocates, or more compression, twin plug and a cam on something smaller. I’m putting a twin plug rsr spec 2.8 in my car. I like to rev.

As Matt says the way to get 220hp out of a 2,7 is by spinning the motor up. You won't have much power below 4k rpm.

My dream motor would be a 2,9L, dual plugs, mod S cams, and 46mm Webers , or if I win the loto, high throttlebody injectors converted to EFI. With that I would have the best of both worlds.

BTW, the '71 trans should take that kind of power, as long as you don't try doing burn outs.

Awesome thoughts guys. Seems everyone is centering on a similar pattern.

2.7/2.8
proper headwork to breathe
cams to match, and tilt it towards a revvy motor
dual plug
higher compression to allow 91 CA crap gas
all the little tricks for oiling etc
proper studs, casework, machining to make it reliable
I'm probably settling on an ITB type EFI Motec, possibly coil on plug
I just like EFI, I know, not period.

I don't do burnouts, but I don't drive the car soft. I do shift proper as I don't like spending too much $ with GT Gears :-) I really enjoy driving the 901, it does shift nice. I do need a diff tho Matt!

Once you build an engine you won’t have any choice but one wheel burnouts unless you get a diff.

+1...this is a good basic recipe for a great canyon carver engine...................

regards,
al

Craig (Pelican screen name: Cgarr) can do your heads how you want them. He does fantastic work, is fast, very reasonable, extreme pro.

I’m already getting some break away/spin in tight canyons now with the 2.7 that is in it on 2nd gear exits.

So yeah, a GT Diff is in the plan as part of this. :-) I’m not used to non-performing open diffs in my 911s!

Why not convert what you have to EFI?

Mainly because I'm a 'do it once' type person and if i'm going to go that step i'll build the rest of the motor, and likely, the transmission at the same time.

For now, I'm just driving the piss out of the car, and it's fine. But, another reason I want EFI. I live at sea level. Car runs/starts/drives fine. Drove it yesterday after sitting for 3 weeks (was on vacation) I take it up angeles crest hwy, which goes up over 6000 ft. Car starts to get spitty... and a dead spot in transition from idles to mains. Maybe that is fixable? But then it drives ass-y at sea level... CARBS!

I talked to a few builders and have an idea of the $ it would be to do it the way I would want it. BTW, doing EFI vs. MFI... MFI is probably more $.

Your original post stating your desire,

"My goal: a lively, revvy motor, not 'peaky', reliable, can drive it hard, canyons and occasional track/DE/AX, call it around 225HP," is exactly the engine many want.

This revvy engine will require an efficient use of the limited air mass, lightweight componentry, and a serious look at friction reduction.

The engine configuration has to change from what is typically offered along with how you manage the air supply. Its a basic shift in thinking here. With limited air supply, to get the engine to rev quicker, you have no choice but to lighten up the masses involved.

To make use of the engines ability to rev quicker, you have to manage the air you have to work with more efficiently. This doesn't necessarily mean you have to port for more air, (more is always better), but use what you have better. Accelerate the valves off the seat quicker, less mass to lift off the seat, less force to work against in doing so, but having control of the backside as well.

Making use of the turn around at TDC to help with this limited air exchange and increasing the change of direction at BDC to help increase the efficiency of the piston as it does nothing to help performance at the bottom turnaround.

We are involved in a 2.9L project at present where we have changed the basic configuration completely, spent a lot of effort on lightweight components, and a new cam design that is part of our new "inventory". Our goal is about engine acceleration, getting into the useable torque not so much outright HP. It will be nice to have both and we do have a HP goal in mind.

After spending many years involved with the water engines, its fun to be involved in these earlier engines and there is so much new development that can be done to help their performance.

There is life still left in these older engines. I believe that the early mag cases have probably done all of their shape changing and have seasoned into some sort of reliable engine case. As the lively revvy engine is part of the sum of all parts required to get that performance, car weight play huge part here too. A mag case certainly helps in weight reduction.

I get it. If it were me, if you really want to build something, I would have another engine built and then sell the 2.7 that’s in it. Even better, get a complete set up engine and trans built, and then swap that in and sell the 901/2.7. My point was more like “you have a good non-numbers marching engine now with a fresh rebuild, why not adapt that simply with EFI v. a full build.”

Anyway, I vote for a 3.4 turbo build or 3.6/3.8 build either with a G50. :) Do it once as you say. And the cost to do a rebuild on a nice engine v. an engine that actually needs it when you are replacing basically enverything but the case is not huge. Plus swapping a drivetrain is much quicker than waiting while your drivetrain is rebuilt.

“There is life still left in these older engines. I believe that the early mag cases have probably done all of their shape changing and have seasoned into some sort of reliable engine case. As the lively revvy engine is part of the sum of all parts required to get that performance, car weight play huge part here too. A mag case certainly helps in weight reduction.”

Neil - I was under the impression that mag is such a reactive metal that it just keeps getting more and more brittle until it crumbles. I don’t think time is it’s friend.

Yes very true, but many are discarded with life still in them. Not all are trash. There is also treatment that can be done to mag to help it last longer. Dow (number) I think its 7, is a treatment yo can do to mag.

But yes, you are correct, some are well past their shelf life. These are generally from engines that have never been looked after.

MORE POWER! :-)

I have a 964 hot rod, and a 997 GT3RS to feed that dragon.

Having driven a few of these, it feels to me that low-mid 200HP range is just 'right' for the chassis. But that's me!

Ok so I'm mentally getting closer here. I'll likely buy a core and build that, or if a good core swap it in car and build what I have...

Question: What are folks doing on oiling? I think the stock oil pump is a weak point? 3L or 3.2L pump?

A 2200-2300lbs 911 is just right with 250-280ish bhp. Stock brakes are scary tho!

I find them pretty good for the weight of the car and keep in mind i have 2 other cars with insane brakes to compare to.

A couple of things to keep in mind, depending on what core you are talking about.

'71 was the last year of the smaller oil lines and oil tank. Newer motors had more oil capacity and flow. So you will need to address oil lines and the tank. Adapters are available but with a larger more powerful motor you may want to upgrade the tank, and most likely you will need a front cooler. With your 2,7 perhaps some of that has already been addressed?

What intake, exhaust, ignition, and gauges will you need to match the new motor? If you are sticking with a 2,7 it will be easier than a 3,0 or newer.

Will do a 2.8
Have a carrera cooler already installed
Intake will be some sort of itb efi plan there isnfull motec dual coil on plug crank fire ignition
Exhaust is ssi currently with dansk sport muffler.
Not sure if my oil tank has changed, likely not but, seems to be ok with current 2.7 and car runs cool

Hey have a question:

On the oil tank. So the car has a carrera cooler with the thermostat installed. It runs a rock solid 170-180 in normal use. Hard driving in the mountains in hot (like 90+) i've seen it get up to 200 or so.

If I were to get a later tanks, I assume, need a 73 tank? (72 is totally different right?). What other 'parts' would be needed for hoses, etc?

I have a 77 911S 7R engine core I just got we are starting to disassemble. I'm going to build a different engine and then swap when done, and then refresh the one i have in the car now for another project. (won't 'build' it). First order is a huge machining bill from Ollies :-) I'd love to get 250 wheel, will be doing EFI, dual plugs coil on plug, 2.8L, and all the tricks. With EFI, suspect 10.5:1 is doable on 91 pump gas?

For gauges, will keep it all stock, will update the Tach for a new redline, I suspect around 7500. Will use stock oil pressure/temp senders. For tach signal, not sure.

Without knowing the details of your current setup, it is hard to answer.

What engine case are you running now and which thermostat for the front cooler?

Maybe post some pictures of your oil tank and set up?

I am assuming you have a 2,7 from a '74 or newer car? If so it seems that all the issues have been dealt with already by whoever did the upgrade.

Thermostat + front cooler are elephant racing setup - so a carrera type thermostat in front of the rear passenger wheel. It works very well. Although fitment was not "bolt in " but I told them what we needed - 77 engine with a 71 body and they got 95% of it right. All the stuff in the rear/piping was good.

I'm 99% sure oil tank is stock

Case is a 7r from 77. New motor will be same, 7R case with all the tricks done once completed.

Anyway, car runs cool with current motor, after cooler never seen it over 210 even with very hard driving in hot weather. The new build will be a more powerful motor. It will also be running EFI (Motec most likely) which should allow for better control and engine management.

So the new motor will bolt in. I suspect if I wanted a later tank I'm looking at modifying some of the piping from the scavenge back to the tank? I DO plan to use a larger oil pump, probably a carrera pump.

OK - I found some pictures at EarlyS
http://www.early911sregistry.org/forums/showthread.php?44022-Pictures-of-the-different-oil-tanks-amp-senders

Looks like: i need to modify the body sheet metal some due to swap of filter and filler. And, adapt existing hoses or go larger with new made hoses. Hm.

It sounds like you have the adapters or special hoses for the '70 tank you have now. Yes, you would have to change the two fittings or oil lines that hook to the tank if you choose to upgrade to a newer tank.

Yea there is some minor sheet metal work that needs to be done in the engine compartment due to the different orientation of the filter.

What type of hose do you have now that connects from the oil cooler on the motor to the oil tank? Do you have a hose that goes over the trans from the right side of the motor to the thermostat?

Here is my tank. You can see the patch for the original filter location.

http://forums.pelicanparts.com/uploa...1566758562.jpg