74 Turbo Project
 

We finally completed the 74 Turbo project we've been working on.
What a sweet ride.
3.0 non intercooled, twin plug turbo.
Supertec twin plug distributor w/ BurnBros Marelli conversion
Taylor wires custom made
935 pistons
911 SC cams
SUPERTEC head studs
38 mm ports In and Ex
K27
B&B headers
1 MSD 6Al triggering two Blaster II coils.

On the test drive we made .1 bar of boost @ 1800 RPM climbing my hill.
Full boost of 1.0 bar @ 3400.
No dyno sheet yet but what fun.

http://forums.pelicanparts.com/uploa...1127323421.jpg http://forums.pelicanparts.com/uploa...1127323441.jpg http://forums.pelicanparts.com/uploa...1127323455.jpg http://forums.pelicanparts.com/uploa...1127323501.jpg
http://forums.pelicanparts.com/uploa...1127323908.jpg http://forums.pelicanparts.com/uploa...1127323917.jpg

Henry,

Very, very nice!

Eddie

'71 914/5

Nice Henry, I love seeing that 12 plug dizzy tucked in there. I see one in my future;)

Nice!

Henry, would that fit under a stock flat deckild? 9 or 6 bolt crank?

This engine would fit nicely in a narrow bodied, no tail car.
Sleeper?
The engine was custom build using a 1980 911SC core. 9 bolt crank.

Yep, thats what I was thinking. thanks for the quick response.

henry

firstly, nice work (as always)

secondly, was there a specific reason for not using an i/cooler (classing?)

First, we know turbos perform better and safer with an intercooler. That said here are the reasons.
We were trying to make 350 hp not 400+
No need for a turbo tail. sleeper
Something different.
Cool looking.
Reduced turbo lag.
This engine under load starts making boost at 1800 rpm.
Try that with an intercooler.
And the main reason we chose not to use an intercooler was that I have built several of these in the past and they're just great fun to drive.

Henry I am having my 79 3.0 SC engine rebuilt, I fabricated and turbocharged it and am using it in my 914. I added an intercooler to it and was planning on boosting it to 11lbs. I am using the stock cis and a 7th cold start injector for enrichment.
I use a MSD BTM for ignition retard with the SC distributor. K27 turbo, Tial bov and wastegate.Everything has worked very well at 9lbs without the intercooler.

? What do you recommend for piston and cylinders and compression for my set up, and should I twin plug it.
This is a street car so boost would be as short bursts now and then 350 to 400hp will be plenty for my joy rides.

henry: thanks for the explanation - fun ride!

Just for *****s and giggles I wanted to see where my motor starts boosting.

I was in 4th gear at 1500 rpm and I booted it. At around 1800 rpm I saw positive pressure. That is my boost threshold.

I also noticed no difference when I installed a large intercooler. I think it is a wives tale that intercoolers increase lag. Kinda like the internet rumor that the G50 weighs 100 lbs more than a 915:rolleyes:

If you think about it. The increased area in an intercooler is small and the turbo moves a TON of air. Hence no increased lag;)

Deanhttp://forums.pelicanparts.com/uploa...1127780421.jpg

Hi Henry, just found this. What compression ratio and cams did you use for this? thanks in advance.

Henry, Please let us know when the twin plug distributors are available.

7.5 to 1 with 911SC cams.

[QUOTE] Originally posted by iamchappy
Henry, Please let us know when the twin plug distributors are available.
The conversion distributers are available now. Look on Ebay

Henry, do you have any recommendations as to pistons and cylinders to fit on a 79 SC engine. I would like to run up to 11lbs of boost with an intercooler.
With all of the options out there right now I cant decide. What would you fit and would you increase the displacement.

The 74 project used 935 pistons and 911 SC cylinders.
I'll check my stock if you would like.
We have also built a few engines using 3.3 turbo piston on a 3.0 crank. It requires some rod modification but it is a reasonably priced option to make your engine larger. These engines turn out to be something like the 935 IMSA 3.12 liter. Those silly things made over 700 horse with IMSA legal booth. 1.4 Bar?

Just checking but do you have an exhaust (header system) or intercooler yet?
I have a 914-6 turbo header and intercooler for sale. If you might be interested I'll post pictures.

I have everything under control as far as plumbling. I like the idea of replating my existing cylinders and fit them with the 935 pistons, please do let me know if you have any nice ones and PM me with a price. http://forums.pelicanparts.com/uploa...1128635017.jpg http://forums.pelicanparts.com/uploa...1128635098.jpg http://forums.pelicanparts.com/uploa...1128635188.jpg http://forums.pelicanparts.com/uploa...1128635214.jpg

Is there any boost retard built into the distributor?

The distributor has both mechanical and vacuum advance so when the boost comes on the vacuum goes away retarding the timing

So at 0 bar and 1 bar the advance is the same?

No
The distributor has both mechanical and vacuum advance.
As for the vacuum advance, because we use a dual vacuum pod we get a dual action.
With vacuum we get 3 degrees of vacuum advance.
At zero boost/ vacuum we get 0 degrees of vacuum advance.
With booth the advance can starts to retard. The more boost the more the retard until it reaches 2 degrees of dist. retard.
Now, the mechanical advance works independent of boost. It only cares about RPM. The higher the RPM the greater the advance until it reaches full advance about 12 degrees @ around 4500 RPM.
We then set the dist. at 30 degrees no boost.
That is about 0 degrees static.
max advance about 30
0 at idle
20 degrees @ full boost @4500
This allows us to run 1.0 bar of boost, no intercooler, street gas with 7.5 to 1 comp. with no detonation.

PS: the horse power and torque is great.

Henry, it was very kind of you to give me some of your time today over the phone. Your suggestion of using the 3.3 turbo pistons and cylinders over the 935 pistons in my 3.0 cylinders has me rethinking and going in that direction. Could you please post the rod modifications for me with the bore and offset with explaination, my notes got the best of me.

We have installed 3.3 (97mm) pistons on the 3.0 crank many times in the past few years. But it's not that easy.
Some back ground.
The 3.3 has a longer stroke but a shorter rod. To make it all fit and maintain the same overall engine dimension Porsche raised the pin location in the piston. (pin height).
The stroke is 4mm more, but the rod is only .8 mm shorter.
That means they raised the pin height 1.2 mm because the stoke made a 2 mm difference at each end.
Here's what you do.
Remove the old pin bushing.
Off set bore the 3.0 rod end to fit the 3.3 bushing. Remembering that we are trying to make up for the different wrist pin location, set the bottom of the new hole at the bottom of your existing hole.
This will give you almost 1/2 of the rod length you need.
If you want all the the deck height back you will need to make a bushing that has a 3 mm larger OD with a 20 mm id and install that bushing in the 3.0 rod. Now you must off set cut this bushing .5 mm. This will give you the proper deck for normal installation. When you're all done your rod length should be 2mm longer. On most Porsches longer rods are better.
Higher compression pistons, no CE rings and longer rods, all good.

Henry thanks for the the info, it seems like a lot of work but probably not in the hands of a competent machinist. If I were to stay with the same displacement then the 935's with the stock re-plated 3.0 bore would be the cost effective solution and produce an engine similar to your 74 project in this thread. I will stay in touch with which way I choose to go.

Henry, don't want to bug you, but did you ever get a dyno sheet for this project?

The car is out of my control, but if the owner chooses to get it dynoed and then release that information to me I will gladly post it here. Until then, he's driving the wheels off the car, as he should.

Henry,

Slightly off-topic I know but what engine modifications do you recommend for '76/77 3.0 Liter 930 Turbo?

TIA

Henry, I didn't mean it like "go out and get me a dyno test for this motor pronto!!" I just noticed you said "no dyno sheet yet but what fun" on the first page, and I was curious. I think this and the 2.8SS are now 2 of my favorite 911 engines running around.

Now, how difficult is it to Motronic-ize a 3.0T like this? I was thinking of perhaps a non-IC, twin-plug, Motronic, SC-based engine with 3.3T p/c...a 3.1T beast!

It would be no different than building one with an intercooler except you would not have to fabricate an intercooler.
It seems like converting a 3.2 to a 3.1 might make more sense.
Either way great fun is in store for some one who builds this engine.

It depends on what you are looking for.
I like increasing the compression ratio slightly, porting to 38, SC cams (even better than 964). If the engine is coming completely apart, a 3.1 conversion makes sense.
Twin plugging on a non intercooled turbo is also a good idea.

The magic to 3.1 (70.4x97) is that the pistons set are readily available and when the rods are lengthened to use the 3.3 pistons, the engine spins with greater ease.

I like the idea of a non-IC, twin-plug sleeper, but with Motronic. Would it be good to use 3.2 heads? I kinda think so...I'm thinking you are right on using a 3.2 as a base instead of an SC...The 3.3 p/c did seem like the "magic" combo when I first considered them (and recalled your descriptions of rod length:stroke and the optimization thereof)! Now, how much more difficult/expensive is it to do a Motronic-based turbo, with the plumbing, etc.?

Great info, but what about the 6 bolt crank as it uses 2.7 rod?

If you want all the the deck height back you will need to make a bushing that has a 3 mm larger OD with a 20 mm id and install that bushing in the 3.0 rod.

This is the part that concerns me, make a bushing.
are there bushings available that can be machined to these spec's or are there after market bushings available for this modification, or do I have to start a foundry in my garage.

Any good automotive machine shop can order custom bushings.
If you have trouble, let me know.

As for 2.7 rods, they are the same as 3.0 rods in lenth and pin diameter. The only difference is the big end. On the 3.0 the big end is narrower.
3.0 is 21.8 mm ? and the 2.7 is 23.2mm ?.

As 959 engine is 2.85 (95x67) twin turbo, haven't you ever thought about building a 2.8SS turbo?

I thought about it but I built a 2.5 turbo for the "914 From Hell" instead.

Would twin plugging be your advice for using intercooler also. I have a 3.0 l also and plan to use 2*GT25. How about 964 RS cams?

K

K:

I'm going with GT20's. How many rpms and what boost target are you shooting for in the end? Aren't the GT25's getting pretty big for a 3.0 (pure question and nothing meant)? Twin plugging would be MORE important without intercooler. Depending on compression, piston shape, bore size and rpm twin plugging could make sense.

Update...
 

The car is running great and feels incredibly quick. So quick, that I fitted a safety devices roll cage for safety!! I also fitted a duck tail and am in the process of removing the rockers. I thought I would enhance the sleeper effect. I am going to have the car on a dyno within 2 weeks and can't wait to see the numbers. When I get the numbers, I will post them here.
Thanks again Henry, for such a fun ride.

Bryan

Henry,

Could you elaborate on the "1 MSD 6Al triggering two Blaster II coils"

Thanks
Scott