gemellocattivo.com

11-27-2007
I think the "occasionally" part is key.

I had harley with a 96mm stroke that I would shift at 8000 at the drag strip and it was happy...stock rods.

Same harley with a new 83mm stroke that I road raced a couple years and shifted at 9000...I still have the bike, it's next on ebay I think. I ordered carrillo rods for it because I needed a custom length, but they were a ridiculous lead time back then…and I didn’t want to miss the first race, so I took the stock rods and cut an inch off the small end and welded a new small end on and put them in the engine….and raced them for 2 seasons.

That engine would live all season if I shifted at 8000, but at 9000 the rings and other stuff was spent after 2 race weekends which was maybe 4-6 hours of track time (hp peak was at 8600 so I liked to shift up near 9000). Load is proportional to stroke times rpm squared, so it a 78mm stroke is ok to 8000, then an 86mm stroke is the same loads at 7600, the piston speed is higher, but the loads are the same.

This car will never see a road racetrack while I own it because guardrail hit don’t buff out. It will go to the autocross from time to time. I’m not scared of the stock rods (with good bolts) with an 86mm stroke and 8000 rpm for occasional use, better rods would make me fearless.

The bigger concern I think is if there is a point to reving to 8000. With a stock QV engine there really isn’t any point to it because the hp is dropping after 6800. when you plug the torque curve and gear choices into excel, the 7700 redline is the best place to shift, but just barely, any more in the top gears at least would be a mistake.

I like the concept of building an engine that is safe to 8000 but leaving the “normal” use shift point around 7500. I'll run the biggest bore I can, then pick a stroke based on the air flow I can get through the heads. It will sounds the way it should sound and I don’t have to go through all the trouble and extra work of having to changing the face on the tach to correct the redline

11-27-2007
The whole stroke issue might get settled easily....one of the 2 guys I asked about stroking the stock crank told me he doesn't recommend it and gave me a contact to have a new crank made, which is obviously not in the budget. In theory I could make a crankshaft myself. I made one for a harley once and it worked, and I've got access to a large enough lathe but I think I've got plenty on my plate already so I don't see that happening. I haven’t heard back from the second place yet.

I got an interesting email from a friend today. Apparently a friend of his is a partner in a small ecu company and offered to design and install an engine control system for me….which is way cool. I had a motec that I got a deal on, but I had optioned for the supercharged V8 so I sold it (to pay for the cool TR heads) thinking I’d get a another one optioned more appropriately for the V12 when the time came, so I’ve got nothing at the moment. Hopefully something good will come of this.

Heres who they are:

http://www.vems-group.org/

11-27-2007
I've been on a 3 year development cycle with this car I think......and a supercharger would be cheaper then the custom crank.....

11-27-2007
There is absolutely no good reason to stroke it other than I got it in my head the it would be pretty cool to get to 6 liter….double stock. It serves no other purpose really. It would give more torque, which I like, and if I could have done it for $1000 I would have but I think that’s dead at this point.

All joking aside, I see no reason to supercharge this engine. I’m pretty sure I’ll be able to ring about 600 hp out if it as it is and that is about 200 hp more then plenty and I don’t want to mess with what should be a magnificent sound. There is no supercharger in the future that I see.

11-27-2007
I just gave the vems site a good read....it appears to be an improved version of a megasquirt and my initial feeling is that I'm not in love. I'll talk to the guy and see what he is willing to correct, but I have the feeling it won't be enough to sell me even a free system.

It uses the same 12x12 ignition and fuel table set-up as megasquirt and I just don't think that is enough to get a good tune on a street engine. haltech is 32x32 and motec is 22x40 I think and I think it’s for a reason. My first haltech was 16x 16 and that really didn't cut it, there were spots that weren't quite right that I could never quite fix. My second haltch that had 32x32 tables never had any such problem. It might have been processor speed related too, and this is a naturally aspirated engine so it won't need quite as many points but....

This system will do sequential injection and waste spark on a v8 and it also appears to also be able to do twin distributor non of which the megasquirt will do. But it looks like no way to run sequential injection on a 12 cylinder because it only appears to have a total of 12 drivers which leave none for ignition. It is cheap enough to just use 2 of them, but then there’s that 12x12 table problem

We'll see....I would like to save money....so I'll listen before I decide.

11-28-2007
That is a good question and I'm really not sure. I'm sure it makes no difference at all for hp. But the higher the output per liter, the more it matters at idle I think because injectors big enough to feed the max power end up at a pretty short pulse at idle. On the supercharged engine there was a marked improvement in idle/low power smoothness with sequential vs multipoint, but that had nearly double the hp/liter this engine will...so I'm just not sure.

I would probably be willing to yield on sequential for this engine as not all that important. I’m not willing to yield on the 12x12 maps being useless for this engine though. I went over it last night again and I come up atleast 4 points shy of being able to get a good fit the expected shape of the torque curve and even 16 would leave nothing for an unexpected shape variation.

I’m leaning toward twin distributors simple because I prefer to see distributors. That simplifies the computing needs and would let a $1400 haltech E11 handle things pretty well. It has 14 outputs, so 12 for sequential injection plus 2 for the distributors…I need to double check that the software will do that, but I think it will. A motec m800 will do the same thing for more money, and for even more money could also do coil on plug is I change my mind and go that way.

So much to think about…..

11-28-2007
My focus on low end is because I've learned over the years that cars with more torque are just better drivers around town. The supercharged 308 engine was an absolute joy to drive and it made something like 250 ft-lb at idle and peaked at 420. With those kinds of numbers in a 3000 lb car you shift when you please. You want to just leave it in 3rd all the time including redlights? Go ahead, it drives fine. If you feel like a hearing it a bit, downshift and let it spin, that's fine too. If you have the torque you have a choice I guess is the best way to put it. If you don't have the torque, you don't have a choice, you have to shift.

What engine and heads are you talking about Jack? A 400/412? With the stock heads and a little porting they pull to about 6000 rpm with stock displacement, so at 4.0, I guess it would pull to about 7300 and the optimum shift point would probably be around 7800. For any more rpm you'll need more air....maybe you can get it with the stock heads, I'm not sure. revs do sound good though and even at 4.0 it will still have 30$ more torque than the 3.0 you pull out.

11-28-2007
I can't believe any one reading this thread would still be contemplating building a copy of this engine...I sure wouldn't be

I think if you start with an early 365 block the studs will work out much better and you’ll have a 71mm crank vs the 78mm and save a lot of money on the de-stroking. Maybe.

On the trans, I was putting 420 ft-bl to it with the supercharged engine, right about where this engine will be. And the norwood guys build a couple 800hp turbo cars that have to be pushing 500 ft-lb that seem to live. I'm told the shafts and gear sets look just like thr TR gear in dimensions.

edit - the shorter stroke will mean longer connecting rods because you can't low the deck height on the block and the piston has to get to the top.

11-28-2007
You might be right. I'm going to end up with about 30 hours into moving the studs I think. For me that cost about $20 in argon, $10 in electric, another $10 for welding rod and 3 or 4 scoldings from Lana. At the local welding shop it would cost $80 per hour I think.

I'm thinking I see about another 30-50 hours in the head install portion of the job. Then the actual engine install begins and I'm thinking there's 100-150 hours there. Oh then then make headers/exhaust for another 40-50 hour.

This is way less an easy swap than I had hoped it would be....I can hear Charles laughing all the way from atlanta

11-29-2007
LOL

The latest breaking news then!

Yesterday I got a new 5lb box of welding rod and some new gas cups for the tig torch in the mail. I got the argon today and also a new O2 tank incase I want to warm things up faster. Now I just need to fit the leak in the tig torch and I’m ready to get back to welding Saturday morning.

On a more interesting note I’ve exchanged a couple emails with the guy from VEMS about what they can do for a control system for me. The unit is actually more capable than my read of their somewhat lacking web site lead me to believe.

They are now capable of 16x14 fuel and ignition map tables and I think that would be acceptable. The 12x12 tables were my biggest concern really. It’s funny that the computer guys think no engine needs more than 8x8 and they only went to even 12x12 as marketing gimmick….but engine guys (me) wouldn’t even consider an 8x8 set-up because it’s absolutely useless. It doesn't change the peak hp any, but boy does the drivability S*CK when you don’t have enough points. I think 16 rpm point is the minimum as long as they are user defined rpms points and not just evenly distributed (waiting for an answer).

This unit also has up to 20 high power drivers, not 12 like I thought. For you V8 guys, that is enough for sequential injection and COP ignition. It also appears (I’m confirming) that the coil charging control is built in to the ECU, no external ignition boxes to buy and install which can save you several hundred dollars. For my 12, I can run sequential injection and then have my choice of distributor or a waste-spark ignition of some kind. They suggested 2 3x2 bosch coil packs. I’m waiting for an answer if I could connect 2 of the cute motorcycle COP coils to 1 driver and get rid of the ignition wires.

The unit will also run 2 wide-band O2 sensors among other things so it’s not a bad unit and it’s like $700 with the various options.

The real problem I see left is there documentation is just plain bad, they need to spend some time on that. They guy is offering to spec everything and then coming down and help install it and get it working though so I guess in that case it doesn't matter about the documentation. I’ve got a few more questions to resolve, but it might be an offer that is to good to pass up.