Flat Plane Crank LS1

[Ken Roberts]

Purchasing a LS2 GTO motor would be a poor choice. The oil pan has the hump in the front which will not fit in the SLC. The accessory drive will not work. It's much like the F Body in that it sticks out too far. The stock LS2 intake flows poorly compared to a LS6 or LS3 intake.

 

[Cliff Beer]

Troy,

I've been very far down this path before, with a SBF rather than a Chebby, but I can share a few experiences/observations.

1. The shorter the stroke, the higher she can rev. There's two reasons why a ferrari V8 can rev: a) short stroke, b) overhead cams and good valve gear. You won't get a chevy engine to rev like a ferrari w/o building it significantly oversquare, and using overhead cams. Without those two design elements you're going to be limited to something like 7K, maybe 7,500 with really strong valve springs.

2. The toughest part of the project is not the research, it's the getting-it-built. It's easy to armchair build a flat crank V8 based upon an American V8. What's tough is finding a capable and competent shop to build it, and then actually building it. Call around....you'll find that nobody really wants to take that on. Why? Well, no Ford or chevy build shop has any experience with that.

3. Be prepared to spend a LOT of money on the transition from theoretical design to actual build. Build shops don't work for free and there's a million issues that come up in the actual build. You'll find that just giving them specs is only the tip of the iceberg as far as what they need to know to actually build a crank and cam and rods/pistons. When I say "build" I don't meaning building the whole engine, I'm just talking about producing a crank and a cam.

4. People will tell you that it will shake your teeth out. That's just not right - ferrari V8s, for example, run quite smoothly with no need for balance shafts or any other other compensating device. If it does vibrate like crazy when running then that's a design flaw, not necessarily a problem with a flat crank V8.

5. Take a look at the new Ruf V8 for porsche - it's flat crank and very smooth running and has some interesting design features you may want to incorporate.

6. Be prepared for a lot of set backs and extra costs and push back from builders. Builders make money from cranking out a good volume of their standard builds. They hesitate to take on really unique projects like this because there's a worry there will be a lot of (uncompensated) time consumed in add'l design work, and re-work/returns.

I spent over $15,000 trying to get crank and cams built for a flat crank SBF, and had little to show for it in the end. The idea was to get a crank built suitable for a SBF, and two different cams so I could experiment a bit with cam profiles on the road.

I definitely see the value/intrigue in a flat crank V8 based upon an American V8, the main appeal (to me at least) being: simplicity and cost. Sure, you could put a F430 engine in your SLC but then you're stuck with buying $1,000 distributor caps, $1,500 water pumps, $12,000 valve jobs, $1,500 alternators, etc. That all just sucks.

Good luck with the project!

 

[Lindsey]

For the items
Crank- custom forged 3.187 stroke and 1.889 bearing diam
con rods- not sure yet, maybe Carillo if I have money, but the Eagle H beams have the correct size and might be fine for me with 500hp
Pistons- probably JE, but maybe mahle or other forged
Comp ratio- in the 10:1 or so range. Maybe 10.5:1
Cam- mabe 270ish duration and not sure on lift yet
solid roller lifters
roller rocker arms
dual valve springs
ti reaters
lighter vavles, prob ferrea
port and polish
MLS head gasket

Here we go.
Troy

If you want to rev, then spring for the lightest reciprocating parts you can afford including valve train.
With a 270 degree cam you can (& should up the compression) 11.5:1 would be better with quality fuel.
(I had an LS engine with over 12:1 compression with a [email protected]" solid roller cam)
Get an experienced engine builder onboard so you make sure you are putting all the right parts together.

 

[Troy Truglio]

There is only one one off part and that is the crank. The rest is really off the shelf items. The con rods are eagle h beam that are already available. I will get the crank first. Even if I did not do the 180 crank I would still like to rev high and do the same basic thing. I am trying to keep the build with known parts that work. That is why I like the ls1. Easy in that tons of parts. I am used to building engines with almost every part custom and mega money. My 3sgte had like 20k in the motor when done. This will have less than half.

On reliable the bottom can handle it and I just need to make sure on the valve train. He said 9000rpm and reliable. He liked Manley valve train items, but we will see.

 

[Keith]

Do you mean you can use a standard off the shelf camshaft for a 180 degree crank?

How will you balance the motor?

 

[Troy Truglio]

You need a custom cam. But a lot places start with a blank and program into the CNC what duration and lift and it is ground away. Basically the lobe shape and at what degrees you start the lobe. In this case you are really just changed where the love is stated on like half the lobes and the other half is stock.

Balance the motor just like you do a normal motor. Make the crank counter weights the correct size and drill lightness out as needed to balance. Like you do a 4cyl engine.

 

[Merim]

I'm wondering if you could just get a flat plane shortblock from lingenfelter or kurt urban, that way they assemble it completely?

 

[Troy Truglio]

Cliff, you make some good points and I am glad I have some good experienced builders to call on when needed. Here are some points to your comments.
1- I agree a short stroke and figured 3.187 as a good ratio for a shorter stroke and to get the rod ratio where I want it for a high reving engine. I am hoping for 8000 and from the people I talk to they say that should not be hard, but will cost some money for the right parts. The shop I use has revved SBC to 10K+.
2-yah, a normal shop would not and why should they. It will take way longer and more headache for them and almost no profit margin it in. I am trying to learn as much as I can here about the engines so I can build it myself with their guidance instead of relying on them to do it all for me.
3-I am not using a build shop and will built it myself.
4-The place making the crank said the same thing when I asked about vibration and said it should not be a problem if the crank is made correctly. He said it would if an all out race motor with a 19lb crank. They said it needs the counterweight a certain way to balance out the engine correctly. I was like, ok, you have done it before a bunch of times and I trust what they say. They did not BS me on other hard questions so I think it can and will be a smooth engine when done.
5-I read about the RUF V8 in Excelence and that looked good. I need to read up on it some more and that is a good idea.
6-I am building it myself. BTW- I have a small machine shop at my shop and the basics. No CNC as I did not feel it was worth it for the time, but I have all the basics to make what is needed with time (mill, lathe, long band saw, sanders, cutters, MIG, TIG, ect). I might make a crazy intake when it is all done so we will see.
7-15K on a crank and cams. Dear lord that is not fun. I found the crank for $2500 and I am working on the cams now, but did find that I can get it done for $1000ish already so I am looking for other options now.
I agree on simplicity and cost. This is my first GM V8 and I am truly amazed at what is out there and the cost of items. For example. Forged JE FSR pistons, rings, pin and clips for $700. I am like, really, $700 for 8 of them. I paid double that for 4 custom ones for a 4cyl turbo project. I paid double for valve springs and retainers for 4cyl engine.
The real item I am researching now are which valve train items to use and think I have a lot of that sorted out now. Solid roller lifters, chrome moley push rods, Jesel rockers, Springs - Dual with Ti retainers or light steel (not sure yet as I need to figure out seat and open pressures with the lift needed for the cams so that will come), valves- either Manley or Ferrea, port and polish, valve job.
I have been pondering it for a bit. I am lucky in that I have a machine shop/ race shop that basically does crazy things all the time and they have basically adopted me there. I can go and assembly the engine and have them help me do it to make sure it is right. I think that is what makes this a doable project for me. I have built a few motors already and know the basics of what is involved.
On the cam, I do not understand how that would be hard for someone to do it? We have 8 cylinders in cross plane mode and 4 cylinders are in the stock configuration to the lobe location. I will adjust the duration, lift, lobe separation and profile myself as anyone would do when getting cams made. So when they program in to grind the cam from a blank they can just base it off of the correct stock cylinder locations and go from there. From a programming and CNC perspective it is no more work than any other custom cam.

 

[Alex]

At least you're not trying to stick a 6-cylinder in there anymore, haha

 

[Troy Truglio]

At least you're not trying to stick a 6-cylinder in there anymore, haha

True. Funny thing thing though, the v6 twin turbo when done would make more Hp, but this is more of what I really want to do. It does seem like their are two camps though. The, you will have some problem and it will never work crowd and the that should be amazing when done group. I guess time will tell.

 

[Josh]

 

[Troy Truglio]

Quick update. I studied firing orders today and finally figured it out. I am going to match Ferrari here and my thinking is that they chose that order for a reason so stick to it. They basically use two 4cyl that are standard 1-3-4-2 that I am used to so it makes sense to me once I figured it out. The thing that threw me off for a long while was their order did not make any sense at first, until I found out that they number their cylinders different then Chevy. Once it was done it is all good. 1-6-5-8-7-4-3-2. I figured out some other items in the build and will order the crank tomorrow morning.

Another thing is that I can use the stock ECU and Harness for this. I just need to rewire the cylinders for the firing order. At least I do not have to rewire cyl 1 and 2, the rest will be done. Then I can just use a more simple tuning solution that a full stand alone as it will be NA, just need to be leaned out a bit due to smaller overall cubic inches.

I talked to the shop that will help me assemble and build the motor. They suggested a short runner intake that might have to be custom made for it in the 10" total length range. Good thing I have a smallish machine shop at my place. The OZMO looks good and I might copy that design a bit. Maybe some CNC for different parts and then some carbon for the it also so it can look amazing when done through the glass. I looked the Ferrari intakes and they look similar. We will see what we come up with. I just reread a few hours of older material refreshing my mind on the calculations and what is needed.

On the exhaust I am not sure if I should do a 4-1 or 4-2-1, but that will come way later. The F430 is 4-1

 

[Merim]

For the pcm, all you need to do is repin the firing order at the pcm, its that easy. Ive done it to use a 411pcm to run a lt1 engine which has a different firing order

 

[Troy Truglio]

For the pcm, all you need to do is repin the firing order at the pcm, its that easy. Ive done it to use a 411pcm to run a lt1 engine which has a different firing order

Brilliant! Now we are talking. Now I need to research how to tune the stock pcm. Seems like HP tuners has what is needed and should be farily easy to use?

 

[Cliff Beer]

Troy,

Sounds like you're on the right track in all respects. You've obviously thought through it all, and that's great.

I know it's been done before with a chevy engine, I'm just not sure how successful it was/is. If done with care and planning there's no reason why the specific output shouldn't come within say 80% of a ferrari V8. The delta is obviously due to multi-valves, variable valve timing, higher reving, etc. Perhaps you could get close to 90hp/liter?

In any case, as you know, the primary benefit of the flat crank configuration is that the engine winds up faster due to less weight in the crank. Your builder is right, you'll need some counter-weighting, but not much I wouldn't think. Besides, counterweighting doesn't work that well on a flat plane crank because the throws aren't in the right phase.

You might want to chat with the Lingenfelter folks too, they may have some good insights and be willing to share them. Please post pics and updates as you move forward!

[ame=http://www.youtube.com/watch?v=ZPx6_R5m0xM&feature=relmfu]Lingenfelter Flat Plane LSx intro - YouTube[/ame]

 

[James]

Troy,

Sounds like you're on the right track in all respects. You've obviously thought through it all, and that's great.

I know it's been done before with a chevy engine, I'm just not sure how successful it was/is. If done with care and planning there's no reason why the specific output shouldn't come within say 80% of a ferrari V8. The delta is obviously due to multi-valves, variable valve timing, higher reving, etc. Perhaps you could get close to 90hp/liter?

In any case, as you know, the primary benefit of the flat crank configuration is that the engine winds up faster due to less weight in the crank. Your builder is right, you'll need some counter-weighting, but not much I wouldn't think. Besides, counterweighting doesn't work that well on a flat plane crank because the throws aren't in the right phase.

You might want to chat with the Lingenfelter folks too, they may have some good insights and be willing to share them. Please post pics and updates as you move forward!

You can get close to 90hp/L now. You can get 550hp out of an LS3. That's 88.7 (I'd call that 90 in my book).

The only HP advantages of a flat plane crank are:

1. The exhaust scavenging is increased because there are no double pulses nor is the a big exhaust pulse gap. (180's will do this to)

2. Intake pulses are even, so that you don't "starve" a cylinder. However I think a carefully designed intake manifold could do the same. Basically a "cross-over" manifold.

3. Lighter Crankshaft. Now this doesn't make anymore HP, but it will free up some going to the wheels, the same as a lightweight flywheel or driveshaft. But how much lighter is it.
------what is the standard weight of an LS3 crankshaft? I know Manley has a forged superlight crank that weighs about 47lbs. I can't imagine a crankshaft weighing much less than that. Now such a light crank mandates the use of lightweight pistons and rods because of the way the whole rotating assembly balances itself out.

 

[Merim]

Brilliant! Now we are talking. Now I need to research how to tune the stock pcm. Seems like HP tuners has what is needed and should be farily easy to use?

HP tuners is what I have. I bought the pro version because of the wideband capability and that is the only difference between the two options. It is easy to use and their forums have good support and tips.

 

[Cliff Beer]

You can get close to 90hp/L now. You can get 550hp out of an LS3. That's 88.7 (I'd call that 90 in my book).

The only HP advantages of a flat plane crank are:

1. The exhaust scavenging is increased because there are no double pulses nor is the a big exhaust pulse gap. (180's will do this to)

2. Intake pulses are even, so that you don't "starve" a cylinder. However I think a carefully designed intake manifold could do the same. Basically a "cross-over" manifold.

3. Lighter Crankshaft. Now this doesn't make anymore HP, but it will free up some going to the wheels, the same as a lightweight flywheel or driveshaft. But how much lighter is it.
------what is the standard weight of an LS3 crankshaft? I know Manley has a forged superlight crank that weighs about 47lbs. I can't imagine a crankshaft weighing much less than that. Now such a light crank mandates the use of lightweight pistons and rods because of the way the whole rotating assembly balances itself out.

James, good points, I hadn't thought about the intake/exhaust pulse phasing but that's exactly right - should make a difference as you say.

Regarding weight, the estimates I had of the crank I had in design (but never actually held in my hands) was 33lbs (designed for 331 SBF). It didn't really have much at all in the way of counter-weighting. It was intended to look just about identical to a ferrari V-8 crank.

I picked up (as in held in my hands....) a ferrari F1 crank at the ferrari store in San Francisco. It couldn't have been more than about 25lbs. Of course, that's a small displacement engine, and the throws were so short it looks more like rod billet than a conventional crank. But, holy moly, that was light. If you want to "pick it up" for something interesting on the coffee table I believe it was about $10,000.....

 

[Troy Truglio]

Crank is ordered today. I asked about weight and it will be in the mid 40's and be a fully counterbalanced crank and not a superlight to keep the vibrations in check. The stock is in the 50's he said. So one thing done.

I also found a place to make the cam so that is good also. Now I just need the specs I want and I am working on that.

 

[Alex]

BesBest of luck on your project