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Posted by: ottox914 Nov 23 2016, 02:07 PM

So here's my long sad story. The turbo motor dies several yrs ago, due to a missed shift at lots of boost and rpm's. I bought a recently re-built motor from a forum member to replace it, thinking this was faster and easier than re-building the turbo motor. Lost a year to a new job, selling an house, buying a house, moving to a new state, bring my retired dad along and getting him re-set in a new environment. Put the re-built motor in this past summer. It kept blowing up. Pulled it and fixed it all summer. Kept the seller updated as to my problems with the "good" motor. Called the seller this fall, who graciously agreed to refund full purchase price.

So now I again have a motorless 914. Trying to figure out an N/A build that uses most of the parts in my shed to keep $$$ down.

I have the pieces in my stash to build the following: 2 good cases to choose from, 2.0 crank and rods, some good iron cylinders to overbore to 96, (would need to buy some KB's to fill them) some heads that Len did that are 40 x 36, (about 75% I/E ratio) that he says will flow about 175 cfm at 50% lift. They have a 50.4cc chamber. So these, with some flat top KB's would yield about 10.5:1 with .040 deck. 2x valve springs, Len is comfortable with this head to 7k rpm if I would need to go there. I have the ITB's and SDS efi to run it all, and as the injectors were sized to support the turbo motor, I expect I have enough headroom to run some E85 "corn" fuel to handle the CR. Should also hold detonation at bay, and engine should run cooler on corn. Not a bad thing for aircooled motors. Kerry hunter exhaust to finish things off.

The wild card is the cam. The cam I had in the turbo motor is still good, not damaged by the over rev. Its ground on a 110 center, has a lift of .500, and is a split duration of 276I/284E, with duration at .050 of 240/249.

When researching cams for the turbo motor, seems lots of folks say a factory cam N/A is a pretty good starting point for a turbo cam. When I go to the Web Cam page for the 914, what I got is bigger than an 86, the "street" cam, but not as wild as 86a or 494.

What think the collective? Will the flow of the head, small-ish intake valve, and big lift of the cam play well as a team? I expect to get alot of "its all in the combo" remarks, but with as much as is known about what I have to build with, and the cam being the big ?, looking for opinions from those more cam-educated than myself on options to use what I got or not.

Posted by: ottox914 Nov 25 2016, 06:50 PM

Nothing? Really? Crickets?

So here is my reasoning- A web cam 86 is their street cam at 270*. Their turbo cam is a 276/276. Mine is a 276/284, which should aid the flow out of the lame exhaust ports we have. Turbos make boost. Boost = compression. If I'm running 10.5:1 static compression and corn, perhaps this cam will be work out for me in an NA motor. I seem to recall somewhere that the stock web cam is on a 108 lobe center, my cam is 110, which should favor TQ slightly.

Once again, any thoughts, opinions, experience that will confirm my thoughts or shatter my ideas and send me off on another direction?

Posted by: jmill Nov 25 2016, 07:11 PM

Your cam has 60 degrees of overlap. The 86a has 70 degrees. N/A motors like overlap for scavenging. Turbo motors don't need much. IMHO a small valved engine needs duration more than lift. Whereas large valved engines can benefit from high lift short duration. But me thinks you know more about cams than I do.

Posted by: Mike Bellis Nov 25 2016, 07:17 PM

Since you can't turbo a 914, nobody knows what you are talking about...

Posted by: rick 918-S Nov 25 2016, 07:35 PM

I seem to remember reading that stock Injected engines like longer duration. too much lift and overlap cause a pulse that messes with the maps. At least that is my understanding. As far as ITB's go I have never run them on an air cooled engine.

Posted by: ottox914 Nov 25 2016, 11:34 PM

Thank you for the replies. I don't know all that much about the fine details of cams. Found this calculator. Interesting. The web 86, which seems to be the all around street with carbs/after market efi, is 270 on 108 center, for an overlap of 54 degrees. The web 73, the stock efi cam is 262 on 108, for an overlap of 46 degrees. My current cam, at 276/284 on 110 center, clocks in at 60 degrees. The 86a, which claims to be more mid-upper rpm at 290/290/108 shows 74 degrees. The 86b at 300/300/108 shows 84 degrees.

http://www.wallaceracing.com/overlap-calc.php

What does this all mean? Seems like the lower overlap cams are more tq oriented, the higher more hp oriented. As with the smaller valves I'd be thinking more tq than top end hp, and doesn't more duration generally = more hp at higher revs at the expense of tq at lower rev's?

Open to learning more about how to reason my way thru this.

More interesting cam info: http://www.jdmcars.com/tech/lift_duration.pdf

Posted by: Mark Henry Nov 26 2016, 12:58 AM

It's a 2mm smaller intake valve, I wouldn't worry about it. T4 heads have lots of flow on the intake.
Your CR is too high, aim for no more than 9.5:1 unless you plan to twin plug it.
I'd get the best cam for the combo, performance carb cams have longer duration.
It's the long duration (thus overlap) that messes with the MAP sensor. But if you want the longer duration cam it can be done by running TPS only.

With the turbo cam you have you might have a good MAP signal, but for NA you have to change it to a 1 bar MAP. Your turbo sensor is a 2 bar MAP, so you would have to buy a new one bar sensor.

If you want to run TPS only (or a 1 bar MAP) PM me and I'll tell you how to short circuit the ECU to get into the code and change it to a TPS only (or 1 bar MAP) system.

Posted by: ottox914 Nov 26 2016, 07:41 AM

Hey Mark, thanks for the insights. I realize the CR is more than the usually accepted 9.5:1 for pump gas, but I was planning to run E85 "corn" fuel to balance out the CR. Some guys I auto x with swear by the stuff for their turbo motors. Check out this calculator for CR and boost.

https://www.rbracing-rsr.com/compression.htm

i was running 12psi +/- and around 9:1 static CR. That would have given me an effective CR of 15+, which I was managing on 93 pump and a good tune. I did have to pull timing under boost which I'm sure slowed me down. If that motor hadn't been blown up, and I had the chance to run corn, the results could have been staggering. SDS ftw.

I've got a 1 bar map sensor in the car already, and have changed the SDS tables to match it. I keep forgetting the pins to mess with, but this time made some notes so I don't forget. Again. I had just upgraded the ECU to include gauge mode 4, and was looking forward to tuning with it when the last engine failed, and I returned it to the seller. So I'm a little excited to get this new motor up and running and tuned.

So far as cams- if I'm looking for more TQ and maybe a 6k redline, spinning it to 6500 at an autocross if I need to extend to the next corner, does that change your opinion of re-using the turbo cam? If this results in a more stable MAP, then the TPS tune will be a plan "B" if needed.

Looking to build a 2056 that is a fun, reliable, torque machine that isn't afraid to rpm a little now and then, and just enjoy the car rather than getting all crazy like I did with the turbo project. (which is not to say I won't be seduced by boost again sometime in the future...)

Posted by: jmill Nov 26 2016, 07:48 AM

Yes and yes.

An engine is just a pump.

On a side note, a smaller valved engine can handle more overlap at lower RPM since velocities are increased.

Posted by: saigon71 Nov 26 2016, 08:10 AM

I went with a FAT 440 MP camshaft for my 2056 FI build. It's a little more aggressive than stock and works well with FI. I'm quite happy with it. Here are the specs:

413” lift - 258° duration . Ex . .405” lift - 270° duration

Posted by: ottox914 Nov 26 2016, 04:48 PM

In searching around, seems lots of folks have done the 2056 with the factory EFI and a mild cam upgrade, and been well pleased with the results.

Can we hear from some of the carb'd guys on what their cam choices have been, and what they think about the final product? I expect carb motors will be closer to what my ITB motor could end up being.

Posted by: Steve Nov 27 2016, 11:05 AM

I converted to a six 30 years ago, so I have limited 4 banger experience. My last 4 banger was a 2.4 liter (103mmx71mm). I ran a 285 duration cam with dual 40 webers. Ran awesome, but ran hot and wasn't reliable, so I converted to a six. Curious how many people on this board are still experienced with the fours versus sixes and other power trains. It seems to be getting less and less over the years. Kind of a dieing art, especially the fuel injection. Sorry didn't mean to take this off topic.

Posted by: The Cabinetmaker Nov 28 2016, 07:44 AM

Your wrong Steve. There are still plenty of 4 cyl cars with fi and people who know them well.

Posted by: Steve Nov 28 2016, 01:20 PM

I'm glad I'm wrong. In so cal, I mainly see carbed 4's. I only know of a couple of fuel injected 4's. Lots of conversions to other power plants, but still mostly sixes.

Posted by: The Cabinetmaker Nov 28 2016, 05:27 PM

I have noticed the increase of conversions as of late.

Posted by: ottox914 Jun 15 2018, 11:12 AM

Well, now we got to see how this works out. Motor is built as outlined above, but with 9.5:1 cr and running BP 93 rather than corn. After many long discussions with my good friend and owner of Complete Tuning Solutions we decided pump would do for now. I have plenty of injector if I wanted to try E85 at a later date.

We have 4 hrs of dyno time booked this afternoon, 2 for the 914 and 2 for the CTS vette. The afternoon will be brutal, on cars and bodies. There is a heat advisory in our area till 7pm tonight. But the time is booked, we both took time off work, so here we go. Lots of fans, cool down between runs, watch the oil temps and pressures. I have CHT and EGT gauges to watch also. The bonus is that if we can safely get to the best the motor has to offer in these conditions the car should be understressed in most all others.

No idea how many runs we might get. We have been working on a good road tune for the last year, so after a baseline run we’ll see where the maps might be improved. The SDS has a nice feature to dump more fuel in if you go way to lean. Hopefully with the heat and stress of the runs we never need that feature.

If time and energy permit I have 3 different sets of air horns to try. It would be cool to see how HP/TQ are affected by the different lengths.

Of course there will be a full report to follow.

Still on the rollers. Place your bets on what it makes.

Posted by: ottox914 Jun 16 2018, 12:40 PM

Still trying to get video of final run on to you tube. Had dyno issues. Could not print charts and their wideband was jacked up. We did have the SDS wideband to be sure we were safe, but no way to overlay dyno to sds for the data. Run 6 is tall stacks. Run 7 was short stacks. Other photo is stacks, 1 1/2 vs 6”.

Final numbers were 120hp @ 5500 rpm and peak tq of 124 at 4500 rpm. That’s 138/142 at the crank if a 15% driveline loss is assumed.

Tq is over 100 from 2500-6000 rpm.

I am surprised a little and well pleased at how it all came out.


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Posted by: McMark Jun 17 2018, 07:02 AM

Good numbers. So you're sticking with N/A?

Posted by: ottox914 Jun 18 2018, 01:26 PM

For now. Never say never. While I miss the turbo infused rush of power in the 914, and the problem solving that goes along with boldly going where few have gone before, there are a pair of tuned Audi’s in the garage should I need a boost fix.

Seriously, I probably lost 5 yrs of autocross goofing with the turbo motor, then with the rebuilt (not by me) 2.0 that kept ingesting #3 intake valve, then building this 2056. I need to drive it and enjoy it again.

Building it is fun, but the air cooled orchestra as you thunder thru the gears has its own appeal.

Posted by: ConeDodger Jun 18 2018, 02:41 PM

Seriously David, You're known as one of the faster guys in the MAC. There is a different driving technique for turbo-slam vs: momentum but the line is the same. You can't play the game if you don't have the chips. Go with reliable!

Posted by: McMark Jun 18 2018, 04:43 PM

Yeah, I’m not trying to encourage you to go after it again. The 2.1 is a great engine and it’s exactly where I would stay and be happy, if I didn’t like to experiment so much. Get that seat time and remember why we like 914s in the first place.

Posted by: ottox914 Jun 18 2018, 09:40 PM

Finally got that youtube thing going on. Try this: https://youtu.be/wh_bUMEvKPk
This was our final pull. We hit 120.15 hp and 124 tq. With a 15% drive line loss, this is 138/142 at the crank. More than I expected, quite satisfied with the outcome.

Enjoy.


https://www.youtube.com/watch?v=wh_bUMEvKPk

Posted by: ottox914 Jun 19 2018, 01:42 PM

My thoughts exactly. Not that these things would come to pass again, but I recall an event that didn’t fill. So as a board member I managed to enter 2x. Once in a 1600 lb 2.6 big 4 owned by a friend, and once in mine. FTD in his car, 9th in raw time in my car. Back when mine had a stock 2.0 in it. Now THAT was a good day.

Posted by: ConeDodger Jun 19 2018, 01:53 PM

So you don't have a problem then. With a 2056, you have one of the highest performance Type 4 engines that retains very good reliability. McMark has to experiment. It is not only in his nature, it is what his business is based on.
You're going to be fast no matter what. Put it in the suspension if you want but you don't need that turbo. You're going to be a happier dog if you can go to every event...

Posted by: ottox914 Jun 19 2018, 08:08 PM

Agreed. I have always wanted a 914 that went pppsssssssstttt and had around 10lb/hp. With type IV power. Almost got there. Probably about 15/hp now. Already have plans for some suspension updates for the rest of this season and learn some data logging. In the spring new rubber for the Keizer wheels and back to full attack.