1969 2.0 T to 2.5 S/T Build

[scottjk]

Just turned 56 and decided it's time for me to start doing instead of dreaming. I've dusted off Bruce's original Performance Handbook that I've had since the mid 90's. I've always wanted to learn how to build air cooled motors. Just emailed Stephani to see if she is still selling Bruce's school manuals.
I recently purchased a solid 69 T with running 2.0. Leak down numbers are less than 5% on all 6 cylinders. #4 ignition wire was bad (Beru) causing no spark at #4. Waiting on a top side ignition wire set from JB Racing to be delivered next week. I'll purchase the bottom set when I figure out the twin plug build later on.

I know it's been asked and answered in various ways over the years because I've spent hours reading posts from here to Early911S Registry. I'm still confused on which direction to take my engine build. End goal would be a spicy street engine with occasional track day events not larger than 2.5 while keeping with the S/T theme.

If anyone wants to take the time for a little hand holding during this initial phase of my planning I'd greatly appreciate it and if you are in the PNW beers on me always!

[PeteKz]

Oh, you'll get lots of hand-holding here--we will pull you in opposite directions!

And I'll take you up on your PNW beer offer. Where are you located? I'm in SW WA. Near Vancouver. Buy me several beers and I might even let you test drive my car.

Questions:
1. The picture on the U-Haul trailer indicates that you recently bought the car and dragged it home, so you don't have a lot of time with it yet. What changes does it already have on it, and what condition is the rest of the car?

2. Budget. Even though you'll exceed it, start with a number in mind, otherwise you could end up spending $40K or more just on the engine.

3. Track vs. street? You mentioned "spicy street car" with occasional track use. Advice: You can have loads of fun driving a street car on the track occasionally, but not the other way around. Track-focused cars have too many trade-offs that make them uncomfortable for street use. Yeah, you can drive them to shows and cars'n'coffee, but a road trip would be really uncomfortable.

4. What suspension work does the car have, and what do you want to do? Since you have a good running engine now, I SRONGLY recommend that you focus on the suspension and other stuff first. Do suspension changes one at a time and decide whether you like the changes before the next change. Wheels and tires too. The good news about this approach is that you can keep driving the car, whereas, if you pull the engine for a rebuild, it will be a garage ornament for months, even years. BTDT.

5. Are you considering brake improvements? If you seriously increase the engine power, you may need to add braking capacity. Those can be added before or after the engine rebuild.

6. Do you want to build on the original engine case for bragging about matching numbers, yada, yada? You would minimize down time by buying a core engine and rebuilding it, then swapping it into the car.

Let me beat this to death: DRIVE the car regularly before the engine work. The more you drive it, the more you will figure out how you will actually use it, and thereby what kind of engine you want to build.

[scottjk]

Thanks for the detailed reply. Greatly appreciated. I'm in Seattle but we are routinely in Hood River and Oregon Coast. Place your beer order and I'll bring it down.

I just picked this car up last week. Guy I bought it from had a similar idea of an S/T build but more of an outlaw look. It's a solid car with the usual rusty floor parts but the suspension mounts, torsion tube and structural are rock solid. Perfect candidate I believe but we'll see when it gets dipped. Previous owner installed RSR style front tower brace, Wevo shifter, Rennline engine carrier with Wevo mounts. 15" staggered Fuchs. Aluminum hood and deck lid. S/T R Rear Tail Lights. Came with S/T rear flares not installed. GTS Classic bucket seats. Original suspension and matching 2.0 engine. Mileage shows 76k but I'm skeptical. It was a 69 T but with the S package minus the engine. The original seats are actually fairly nice so might be valid odometer.

I also have a 73 viper green RS backdate on 83 chassis with 78 3.0 CIS engine. It's loud and harsh with a janky 915 and no stereo... and it's a perfect drive for me!

With the S/T build I'm looking to loosely replicate a period S/T that I can have fun driving short distances on nice days... cars and coffee... track events. I specifically bought this car to work on and modify with plans of a strip and dip. I'm shooting for 60k with me doing as much of the work as possible.

Sure wish I would have taken Bruce's engine class! I was bidding on the 'no stone unturned' 2.5 motor on BAT last week but had to bow out at 36k. Would have been a great engine for the car. In my ignorance yesterday I almost purchased a 2.7 R designated case but luckily figured out that it wouldn't work for a 2.3 - 2.5 build. That's why I reached out so I don't get myself in parts hell trouble.

The first photo of the car was from 4 years ago on the broker website here in Washington state. Apparently the previous owner that the guy I bought it from didn't take care of the car at all. It got bumped in the back denting the deck lid, breaking tail lights and denting the muffler. I was shocked to see the difference in person.

So what test drive do my beers buy me so I can plan accordingly?

[PeteKz]

Scott, if you already have an RS look-alike, then you won't be super impressed with my car. It's a street-oriented build. After building a SC CIS 3.2 engine with the M1 cam, I worked on suspension on my car. I aimed for a precise suspension but with lots of compliance, to make a reasonably comfortable ride on the crappy roads in this state. You'll be able to feel what a longhood with 21/26 T-bars and RSR bushings with Koni Sport shocks (set soft) is like. That will give you some idea of what to do with your build.

It sounds like you know what you're getting into, in terms on making your car "yours." Even if you plan to strip it and dip it, I encourage you to drive it for awhile first. Since you have a 1983 RS clone, do you want a more street daily driver on this one?

Re 2.3-2.5 engine--Why not go for a 2.7 build with that 7R case? There's still no replacement for displacement. What induction will you use? Stay with the carbs? I'm not sold on the benefits of twin-plug heads. Adding that drives up cost and complexity considerably for only a modest power increase. Wait to see what's left of your budget after stripping and body work. If cost is no object, then, WTH, go for it.

Rear fender flares: Do you want these or do you want to keep it as a narrow-body "sleeper"? That's my approach.

[scottjk]

Definitely not going to be a daily driver. I'm not interested in a 2.7 due to wanting to keep it close to period. Unlike my RS, which is a copy, this future S/T can be very much like a factory car due to Porsche initially pulling 69 T's off the production line to produce them. It's never been about displacement for me. I'd be just as happy driving a nice 912 as I would a Turbo. For me it's about balance and system relationship not pure torque and hp.

The other issue is I'll be racing a vintage Formula Ford with SOVREN this season and if I decide to run the S/T in some of our events the largest displacement I can use, I believe, is a 2.5.

From what I've read so far I'm leaning toward a short stroke 2.3-2.5 but my engine knowledge is so limited I don't know how to get there. One minute I think I can do it and the next I'm doubting my ability to build it. I think I just need to buy a core and start fiddling with it.

[crater64]

I have a build getting wrapped up as I write; I don't have dyno numbers or seat time with it yet. Starting with my numbers matching case (not a 7R obviously) I wanted to increase displacement without boring the spigots beyond a line bore. I also felt that keeping the stroke short would be more in keeping with a warmed over 2.2T's in-period character. So here's the recipe I landed on with the engine builder:

• case line bored, squirters added and bypass mod performed
• 87.5mm Nickies
• stock 2.2T crank (i.e., displacement = 2380cc)
• stock 2.2T rods
• 10.5:1 JE pistons, which necessitates...
• twin plugged heads
• ported
• Mod-S cams
• 3.0 SC oil pump, given the Glenn Yee treatment
• Weber 40s
• SSIs
• Scart Sport muffler

The goal per the builder is to have "a streetable ST motor than can run on pump 93." Fingers crossed that that's what it turns out to be.

[scottjk]

Please, if you would, keep me up to date. This is exactly what I'm looking for. I'd love to know what the dyno numbers are and how you like it.

I'm assuming with your 70 T it was a 2.2 case?

Any pictures of the car it's going in?

[crater64]

Yes, a 2.2T case.

Here's the donor and recipient:

[scottjk]

Great Color!

I'm assuming your build is also possible with a 2.0 case with a spigot bore for large cylinders?

[stownsen914]

Congrats on the purchase - looks like a nice car.

Pretty sure Bruce's book addresses the 2.5 conversion, but a few thoughts:
2.0L heads are compromise, especially on larger displacement engines. Combustion chamber is larger than 2.2-2.7 heads and just isn't great for combustion + more detonation prone. A 2.0T will have small valves too.
2.0L engines don't have piston squirters, which you'll want for a larger displacement engine. Nikasil cylinders normally require their use, in fact. The case may need to be bored for larger cylinders depending on what size you go with as you noted above.
Getting the right pistons will be important to match your heads, and also to get enough compression with the 2.0L heads and also due to the shorter stroke (e.g. with 2.7 RS 8.5:1 pistons, I think you get like 7:1 on a 2.0L)
I see crater64 started with a 2.2 which has the later heads and depending on year may have the piston squirters too.
All of the above are solvable of course - just depends how far you want to take it!

[scottjk]

Great info. I'm still digging through Bruce's book for the 1st time.

What I might do is start looking for a good 2.2 core. I'm not sure matching numbers makes a difference with a modified T if I decide to sell it later on. It also came with a 4 speed that might change.

[targa72e]

I have recently built several small displacement engines (2.4-2.7) and dynoed each in the same car with same headers and exhaust (car is 914). You can see the information and dyno results in the thread below.

https://forums.pelicanparts.com/porsche-911-technical-forum/1151593-dyno-summary-testing-early-2-4l-2-5l.html

If you want to stay with small displacement (or go 2.7 as it looks the same) several things to think about. For 2.5 there is choice between short stroke or long stroke 2.5. If the goal is a peak power under 7K then either will work. Short stroke 2.5 (66 x 90) has the advantage that you can rev to 8K plus with the right cams where as the long stroke (70.4 x 86 or 87.5) you will generally want to keep the redline below 7.5K. The longer 70.4 stoke crank has a harmonics at high RPM that cause the flywheel to come loose (and other problems). Realistically the rest of the engine will be about the same. So I would say think about engine character and cams do help drive a decision. As others have said you probably want to replace the early 2.0 heads.
That said the engine I will build for my new 914 project, which will be street focused, will be a 2.8. Plan is 10.5 to 1 twin plug, EFI, DC60 cams with ported heads (stock valve sizes) I plan for 7.5K red line.
I also have short stroke 2.5 to build, just in case I am a different mood .

john

[scottjk]

Thanks for the forum link. I'm diving in to your dyno results now!

[PeteKz]

Scott, I'll drop you a PM with my contact info if you want to see what a longhood with RSR bushings, 21/26 t-bars, and Koni Sport adjustable shocks feels like.

[scottjk]

Originally Posted by PeteKz

Scott, I'll drop you a PM with my contact info if you want to see what a longhood with RSR bushings, 21/26 t-bars, and Koni Sport adjustable shocks feels like.

Thanks Pete!

[horizontallyopp]

Originally Posted by scottjk

Just turned 56 and decided it's time for me to start doing instead of dreaming. I've dusted off Bruce's original Performance Handbook that I've had since the mid 90's. I've always wanted to learn how to build air cooled motors. Just emailed Stephani to see if she is still selling Bruce's school manuals.
I recently purchased a solid 69 T with running 2.0.

Hey Scott - just one person's opinion. I completed my engine build a couple of years ago (only took 4 years for many reasons). Did a 2.0E engine (with Webers) to a 2.3 hi compression motor for funsies at Calgary's higher altitude. I used lots of reference materials - including ordering Bruce's manuals. I didn't find them as useful as I thought they would be - to me, they were "class notes" that weren't as useful without the hands on classroom aspect. Between this forum (thank you all), Wayne's engine book and Cole Scrogham's assembly book, that covered everything (including the counter and conflicting opinions). I thought I was super smart and did a TON of work myself - I basically farmed out the machining I couldn't do, bought a set of 2.2T heads on here, and kept my engine build simple to avoid some expensive options (like finding a distributor that would do twin plug, and sticking with the Webers I had), and I still spent $18K CAD ($13K USD). That cost could double in the blink of an eye with more options (twin plug, new Mahle or Nickies P&Cs) and probably triple if you went fancy EFI or buying an MFI system.

As ever, YMMV. Go for it - it's fun and stasifying in the end.

[crater64]

Originally Posted by horizontallyopp

I thought I was super smart and did a TON of work myself - I basically farmed out the machining I couldn't do, bought a set of 2.2T heads on here, and kept my engine build simple to avoid some expensive options (like finding a distributor that would do twin plug, and sticking with the Webers I had), and I still spent $18K CAD ($13K USD). That cost could double in the blink of an eye with more options (twin plug, new Mahle or Nickies P&Cs) and probably triple if you went fancy EFI or buying an MFI system.

Yep! I'd probably have enjoyed building this myself but I know it'd have taken twice as long or longer. Knowing myself I'd veer between rushing and screwing things up or falling into analysis paralysis. Thought I'd better stick to doing what I know best and finding the best available builder I could.

[crater64]

So there was a change by the builder. He didn't want to use the 2.2T crank, so he went with a 2.4 crank and rods:

Originally Posted by crater64

• case line bored, squirters added and bypass mod performed
• 87.5mm Nickies
• 2.4 crank (i.e., displacement = 2540cc)
• 2.4 rods
• 10.5:1 JE pistons, which necessitates...
• twin plugged heads
• ported
• Mod-S cams
• 3.0 SC oil pump, given the Glenn Yee treatment
• Weber 40s
• SSIs
• Scart Sport muffler

Originally Posted by scottjk

Please, if you would, keep me up to date. This is exactly what I'm looking for. I'd love to know what the dyno numbers are and how you like it.

I'm waiting on a printout but I'm told in the range of 215-220hp. I don't know what kind of dyno he has, so I can't confirm wheel v. crank hp or percentages of loss.

Originally Posted by targa72e

For 2.5 there is choice between short stroke or long stroke 2.5. If the goal is a peak power under 7K then either will work. Short stroke 2.5 (66 x 90) has the advantage that you can rev to 8K plus with the right cams where as the long stroke (70.4 x 86 or 87.5) you will generally want to keep the redline below 7.5K. The longer 70.4 stoke crank has a harmonics at high RPM that cause the flywheel to come loose (and other problems). Realistically the rest of the engine will be about the same.

I'm very concerned about this cf. leaving it short stroke. The builder used Clevite bearings but I'm not completely sure of anything else he did to beef up the internals. Redline is set currently at 7300.

[crater64]

Oh, and here's a pic of the finished product that I posted in another thread.

[rswannabe]

Scottjk, welcome! You’ll get lots of advice and encouragement here. As you probably already know, Seattle also has some great resources to draw upon. Where in Seattle are you? I’m in Ballard. I also have a ‘69 that I’ve put ST flares on. I’m currently converting my 2.8 short stroke motor to EFI to go back into my car. I think short stroke (66mm) hot rod motors are truly great combinations and you can’t go wrong going in that direction.

Here’s my motor in process.