3.2 to 3.4 low on power - help me find the way

[infraredcalvin]

A shout out to the engine builders out there, as mentioned in the title, I’m trying to figure out why it seems I’m down on power.

A little background, car is a ‘71 euro 914-6 previously owned by member “0396” He’s since passed, RIP PL, the car was sitting for 4-5 years before his spouse decided to part with it. A few scattered records come with, from what I’ve found, engine specs are as follows:

3.2 case (930/25 215 hp 3.2) (confirmed)
stock internals
3.4 10.5 comp P&C
Twin plug (confirmed)
Web S cams
Webber 46 ida3c (rebuilt by me), w/ K&N type filters (confirmed)

Idle Jet: 50
Main Jet: 150
Emulsion Tubes: F7
Air Correction: 170
Choke: 42

Electromotive dual HPV-1 crank fire trigger (confirmed)
3.2 heads, intake ports 44mm, exhaust port 42mm (confirmed)
European Headers 1 5/8 (confirmed)
Monty dual in gt style 2 out muffler

I will update as I confirm items above.

Here’s the quick story, it running for 5 years, I bought it, fluid change, leak down (less than 1% across all cyl), valve adjust, Weber rebuild (idles at 55, main at 170), new plugs. Fired her up, ran like crap, super rich. After playing with carbs and adjusting ladles and jets to values above she ran pretty good. Felt like she struggled reaching higher rpm (ran out of breath) , took her to first track day at Willow Springs in June, ran fine but definitely no pull out of turns and low top end. Took her to Jeff at Aase in Fullerton, he found timing retard 12-15 deg, added it back, worker her up a bit on the street, top end still felt sluggish. Then Autoclub speedway in August, still no pull out of turns, better rev to redline, but still sluggish. Put her on dyno, got 164HP to the wheels which closely match dyno sheet provided in records from 2006 (169 HP).

So even in stock form seems a little anemic (25 hp or so). But with info provided above, and twin plug work, etc it’s more like I’m missing 100 hp at the wheels).

Please let me know your experiences and thoughts, or if you knew the PO or insight to the build. I searched and read I think all his posts in the engine building forum. Some hints that he may have been struggling with the same thing, but nothing conclusive.

Thanks in advance…

Photo for posterity:

[infraredcalvin]

Here is the dyno sheet. Notice how I make all the torque before 3300 rpm….

[safe]

You are going a little lean above 5500. But I would start by checking cam-timing. I think you would be making max power closer to 7000.

[Classic 911]

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[infraredcalvin]

Originally Posted by safe

You are going a little lean above 5500. But I would start by checking cam-timing. I think you would be making max power closer to 7000.

Talked to an engine builder about the cam timing (before I realized I was making torque so early). But he mainly said I might find a bit more hp in the cam timing, but really cam timing determines where the power curve occurs. He mentioned my major power loss is due to major air constriction in one or several places. As for late lean, I’ll post AFR logs from my LM2.

Was planning an engine drop and check on cam timing today - although that plan may be thwarted by a trip to the ER for my dad, day not starting off well…

[infraredcalvin]

Here we go, 5500 RPM still in the 13s…. But per dyno, I’m not making any power from 3200-4200, if you look at that range on my log, I’ve got a big rich dip, assuming that’s not helping power curve…

[roblav]

That's rather ugly output given the engine setup. HP at flywheel should be about 260 or so at roughly 6800 RPM.
Here's where I'd go:
What's the compression / leakdown? Check it.
Check cam timing.
I believe venturies should be 38mm. IMHO, 42 is too big.
Ignition timing at idle and 6000 RPM?
Primaries, 1.5" for street or 1.625 for race are best.

Good luck!

[stownsen914]

A few thoughts/questions:
- I didn't notice which heads you have on the motor. 3.2? If so, I think those have 40mm intake ports. 42 mm venturis may be slightly large, but I wouldn't think it would much of an issue on a track car.
- It does look a little lean in the higher RPM ranges. I'd want to see closer to 12.5-12.75 AFR.
- Sounds like you got the timing sorted by Aase, but as noted above, it would be interesting to know what it's set to now.
- The Weber style K&Ns aren't necessarily the best, but they aren't going to cost you 100 hp either.
- Cam timing would be an interesting thing to check. It would be a little tight in a 914, but it's possible to check valve lift at overlap (per the factory cam timing procedure) with a valve cover off to see if it matches spec for the cam grind. If it were significantly off, it would certainly explain the power loss.
- In the thread on 914world, I saw the comment about cam timing being off 180 degrees. While that can happen, the affected bank wouldn't make power at all, and wouldn't sound right since it would be a 3 banger. It doesn't sound like that's your problem.

Silly question - are you sure your throttle plates are opening all the way? No flex or slop in the linkage?

[targa72e]

I will offer two suggestions based on some dyno experience.
Check cam timing, Dyno below is from 3.0SC. The SC used the same cam as 3.2 Carrerra. There were different settings for different years. Dyno below is difference with cams at most retarded spec and most advanced. The run with more power and torque is fully advanced.



Second thing to check would be to pull the muffler and try a run that way, Dyno below is different car that had headers with glasspack mufflers attached straight out the back. You could see straight thru the glass packs and owner thought there was no way they could be restrictive. Run with more Power is with glass packs removed.




I would check cam timing and pull the muffler and see if it performs better.

john

[safe]

Originally Posted by infraredcalvin

Talked to an engine builder about the cam timing (before I realized I was making torque so early). But he mainly said I might find a bit more hp in the cam timing, but really cam timing determines where the power curve occurs. He mentioned my major power loss is due to major air constriction in one or several places. As for late lean, I’ll post AFR logs from my LM2.

Was planning an engine drop and check on cam timing today - although that plan may be thwarted by a trip to the ER for my dad, day not starting off well…

If you are in the 13s you aren't losing much power, not 100 hoses anyway. But you can loose a lot in the cam timing, you have cams that want to produce power high up but won't let them if the timing is off. I would also check that the cams are what you think it is if you haven't built it.
I think the exhaust must be really restrictive to lose 100+hp, but its easy to check, annoy you neighbours with an open header test run .

[stownsen914]

Good idea to try a quick run without the muffler. It would be a bit strange for an appropriately sized muffler to cause massive power loss, but who knows, there could be an internal failure or blockage. It's an easy test to do.

[safe]

Originally Posted by stownsen914

Good idea to try a quick run without the muffler. It would be a bit strange for an appropriately sized muffler to cause massive power loss, but who knows, there could be an internal failure or blockage. It's an easy test to do.

First post: ", leak down (less than 1% across all cyl)"

Unlikely with an exhaust blockage, its a thing that can happen in a catalytic converter, but I guess that isn't an issue with this car.

[dannobee]

Being down that much on power is NOT restricted exhaust or cam timing off a bit.

Back to basics, are the throttles opening all the way? Is the fuel pressure dropping at WOT? Are the fuel filter(s) clean and fresh? Since it's an engine swap, are any fuel lines kinked?

Again, check fuel pressure AND fuel volume before changing a bunch of parts. Quick and easy tests. Throttle test: with the engine off, prop the gas pedal down with a stick wedged against the seat cushion, then observe the carb butterflies and physically verify that they're wide open.

[stownsen914]

Originally Posted by safe

First post: ", leak down (less than 1% across all cyl)"

A restrictive muffler wouldn't be evident on a leakdown test.

[infraredcalvin]

Thanks for the info and thoughts, keep them coming. I pulled the engine and confirmed a few more things yesterday.

Confirmed 1.625 primary’s on the headers and 42mm exhaust ports - heads are 3.2 heads, I forgot to check compression before draining oil, but leak down when out previously was less than 1% on all cylinders, I will check again though.

One thing I did notice was on the electromotive setup. From what I read the electromotive fires on both compression and exhaust so this shouldn’t matter, so each coil pack will fire 2 plugs at the same time (IE, 1&4, 6&3, 2&5) but spark plug wiring to the coil packs are slightly off. Firing order is 1,6,2,4,3,5, all the top plugs are on the upper set of coils, bottom on the bottom row, but the 6 and 3 are swapped on both sets, anyone think that might make a difference in firing?

[infraredcalvin]

Pics of the leak down - this was done in feb… when I got the car, prior to running.



Now that I have a few track days on it I’m curious what it reads now… hopefully the same…

[safe]

Originally Posted by stownsen914

A restrictive muffler wouldn't be evident on a leakdown test.

Sorry, misquoted you instead of roblav.

[stownsen914]

Normally on twin plug wasted spark setups like Electromotive, you just want to make sure a given coil isn't firing two plugs on the power stroke at the same time. As long as it's not doing that, you should be fine.

I second dannobee's suggestion to go back to basics. I think fuel supply and pressure may have come up in the 914world thread. Definitely check those things if you haven't yet.

I'd still argue that an internally broken muffler, or cam timing being way off (not a little) can be included on the list of things to check. Muffler is easy to test too.

[safe]

Originally Posted by stownsen914

Normally on twin plug wasted spark setups like Electromotive, you just want to make sure a given coil isn't firing two plugs on the power stroke at the same time. As long as it's not doing that, you should be fine.

Unless one camshaft is 180 degrees off, then 1 and 4 would fire at the same time. It would fire on all cylinders and run pretty even, in theory, but what would really happen?

[infraredcalvin]

Engine is out now, I did some checking on the linkage at the motor, need to check bushings at the base of carb pivot, its a little sloppy. When it goes back in I’ll have to check that accelerator pedal opens throttle fully.



I don’t suspect a fuel delivery issue, I’ve got two filters, both will be changed out again, also a pressure regulator and separate gauge after pump and filter, I suppose I could put a camera in there to verify no loss. See setup in the bottom of next photo.



Also fram filter in frunk after pump, sorry for the bad pics, just want people to see what I’m working with…