308 V12 conversion begins

I decided to do a little more work on the flywheel design. I added a 60-2 crank trigger to the OD so I won't need to hang an external trigger ring on the front of the engine. I also removed some more metal that wasn't really doing anything the best I could tell dropping the weight to 7.0 lb in steel or 2.4 lb in aluminum.
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With the clutch in place.
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Just a little "remember it's all connected….I just shot an email to Jason, my ECU guy, to get him up to speed on some of the latest thoughts.

The info from 246tasman on injector placement got me thinking I really should run 24 injectors to get the fuel mixing well over the full rpm range. Vic point out that with dyno sheets that injector times much over 65% start hurting hp and that means full sequential injection, somebody pointed out coil charge times at 9000 rpm which send me to at least 6 coils….so now I need 30 output channels from the ECU to run this thing an there is not an ECU out there to handle what I would like to do.

Sooooo…..it looks like it’s going to have to be twins. And I still need 15 channel out of each.
Haltech has 14 so that’s out. Motec is also 14 but I could add an ignition expander so I’d need 2 ECUs and 2 ignition expanders and 6 ignition modules…what a mess. I might be able to run 2 electromotives, I’m not sure if it has enough fuel outputs, I need to look into that.

This is where Jason comes in as the VEMS has 20 high power out puts and 4 aux outs if I recall right so that’s all good. I need to find out if the software can individually control 12 injectors and 3 coils and if I can share sensors or I’d need to double up. I know it doesn’t need an external ignition module which is nice. I also need to go over the flywheel with Jason to be sure the trigger I’m designing will work properly with standard pickups.

The fun just keeps coming.....now back to drilling oil holes in cams

 

Exactly....if you change 1 thing you need to recheck everything.

1/2 way through the oil holes, I should have them done tomorrow then on to the timing pin holes Wednesday and back the work shop Thursday to alter the bearing journal width on the intakes to fit the oversize buckets. I'm hoping to get the cams out to the grinder next week…I’m thinking I’ve got a better shot of actually getting a real quote of the them if the parts are in their hands and they know it’s a real job….if nothing else they’ll be gone and I won’t be thinking about them for a couple months.

 

A little tune-up to the tigger teeth to make them taller to allow a radius at the bottom so the part will be easier to make. I'm going to go 4140 steel, I'll order that today.
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I took a look but they really don't seem to have anything that will work out. I'm waiting to heard back about if the VEMS can do the job if I use 2...it certainly has the channels but I'm not sure about the software to do it. 2 haltech E11s wil work if I run 2 or 4 distributors which is not a bad option. 2 Motecs will work I think....I'd have to call someone because they're set-up is very confusing.

I'll probably make sure I set up at least the intake cams so they will accept a rotor drive so I can install distributors if required.

On the I'm cheap front I was getting ready to order the 12x12 4140 RC30 for $286 when I noticed the 10x12 4140 RC22 was only $130 an still very strong metal....but my flywheel OD is 10.125 not 10". Then I realized the OD isn't really an OD, it's the theoretical OD of the lugs that mount the ring gear, not a true diameter. The actual distance top to bottom is 9.86" which will fit just fine on a 10" wide piece of steel. 1 point and $150 back in the budget for me today

 

You have to watch the wording. The E6 is up to 4 injection and 4 ingintion....there are 6 total channels 5 can be divided up between fuel and ignition and 1 runs all the auxilary stuff. The E8 has 4 fuel and 4 ignition. The E11 has 8 fuel and 6 ignition but 4 of the ingnition outs can be used for fuel giving 12 fuel and 2 ignition. The motec M800 is the same as the haltech E11 after you buy the 10/12 cyl enable option except motec also has an ignition expander box available that takes coded ignition signals from the ECU and turns 1 output into 8 or 2 outputs into into 2 expander boxes gives ignition outputs.

Haltech uses all GM sensors and I think the coil on plug with the built in ignitor are also GM.

The VEMS ecu has the ignitors build in to the ecu and drives any coil directly. So for $700 (I think) you get 8 fuel and 8 ignition and 4 more high power outputs for whatever with nothing else to buy. It's pretty good deal....but they don't have the 12 cyl software done (it is 12 cyl capable just not with sequentail injection), they're working on it but it's not real high on the list. It still won't run my 24 injectors and at least 2 ingnition outputs anyway....but 2 will as long as the software allows 2 staged injectors. I need to get an answer to that.

 

I'll take a look at the jag site.

As far as batching the injectors I'd really prefer not to do that. This is going to be a pretty high strung engine by nature....honestly at this point it's shaping up to be pretty much a full race engine which is going to make it a real challenge to keep it mild mannered for the street. True sequential injection improves hp and goes a long way to taming idle and cruise problems. 2 staged injectors per cylinder along with sequential injection per cylinder make tuning the low end dead simple and improve hp even more. The down side on a 12 cylinder is running out of channels in the ECU….so 2 it is but I’m not running more than 2 because 2 is already 1 too many and a pain in the butt to tune, 3 as you point out would be a nightmare

 

The cam oil holes are done. On to the timing holes if the reamers shows up today.

 

I haven’t heard back from my VEMS guy, but I did some reading on their website that was not encouraging. I’ll see what Jason has to say because the software is being upgraded and features added all the time…we’ll see but I think he's thinking I'm an idiot

I did talk to the electronics guy at work and he was quite encouraging….after I convinced him that getting into the ECU and rewriting the code wasn’t a viable option that is

Anyway what I don’t want is 2 water temp sensors, 2 air temp sensors, 2 map sensors and 2 throttle position sensors because they tend to vary which will send different inputs to the 2 computers and it clutters up the engine. He’s pretty sure I won’t have a problem connecting both ECUs to the same sensors just like it’s not a problem to connect more than 1 volt meter to the same signal. The converter in the ECU that reads the voltage should have a very high internal resistance so the 2 ecus really won’t see each other…at least in theory. When I get to that point it’s easy enough to power up one ecu with the sensors connected and see what the read is then connect and power up the second and see if the reading changes

I don’t think I could get away with trying to run both ECUs off the same crank trigger though….although….the trigger needs to be not less than 50 degrees before TDC and not more the 120 BTC for a 6 cylinder engine. If I put the main trigger at 50 BTC for cylinder #1 that is 110 BTC for cylinder #7 I think and acceptable and the cam position trigger would be similar…hmmm…..It just doesn’t seem like a good idea though for some reason. I guess if nothing else as one pointed out the car could drive home with a failure if I have 2 but not if I have only 1. I think I’ll mount 2 crank triggers, 2 cam sensors and 2 TPSs because those are critical and 1 water temp, air temp and MAP because they are not critical to operation.

 

Here's a video of an F1 engine on the dyno
http://www.youtube.com/watch?v=y2iBbwocYZw&feature=related

Looking at it it's clear that the engine has at least 2 injectors per cylinder with one of them mounted high and at least 1 mounted low. There are certainly single injectors big enough to fuel an F1 engine but they was at least 2 smaller injectors instead of 1 large one.

The reason is it's the only way to get the fuel atomized properly at all rpms. I have found in general that there seems to be a pretty big disconnect between the electronics guys and the mechanical guys. As a mechanical guy I want to spec all the mechanical components and simply tell the electronics guys what I need to run it. The electronics guys want to tell me what electronics to use and have me spec mechanical parts to work with it. I read the Megasquirt forums which are dominated by electronics types and almost fall of my chair laughing with the crap they recommend and run.

The more I dig the more I believe what I thought I knew was wrong. I have seen the dyno runs for the same engine on the same day where the only change was to swap the injector type and retune to max hp and the hp changed about 5% as did the mixture the a/f was reading. The only explanation is that one type injector gets the fuel atomized better than others in that particular engine. Better atomization causes a better burn in the combustion chamber and more hp.

Injector time is often quote at 80-85% is ok and at that setting there will be little if any change in hp between multipoint and sequential. But Hp does go up as injector time goes down to below 65% and sequential injection is used. Again the answer is atomization. Now that you have injectors large enough not to exceed 65% duty cycle (and less is better from what I’ve seen) idle and low power are near impossible to control on a high output engine, sequential is mandatory and staged injectors is really the right answer I think.

My personal experience with 60lb/hr injectors (about what I need for this engine) in my qv engine was that they were unacceptable at low power. My injection time even with full sequential injection were about 1ms at idle (they say be scared under 1.4ms and they’re right) and at that short a time my cylinder to cylinder mixture seemed to vary about 15-20% from looking at the plugs. I got it to work, but I was never all that thrilled with low end performance. With staged injectors I can run a small 19 lb/hr or similar injector down near the valve for idle and up to 1/3 throttle and have perfect mixture control and cylinder to cylinder balance and idle injection times over 2ms and nice and stable. Then about a 48 lb or so injector mounted up near the TB can cut in at about 1/3 throttle with a nice stable starting time of 2ms. I think this is the best way to go even if it is more a pain in the butt to set up and more stuff to buy.

As for starting with 1 and adding a second if needed, it’s a ton of extra work if I end up needing it. To run 1 injector I only need 1 ECU. If I need to go to 2 injectors I need to add a second ECU which means rewiring the first as well because ½ the wires will be going to the wrong side of the engine. My thought is that more control can not possible make the engine run worse and it is much easier to just bite the bullet and set it up with the extra stuff the first time then to spend a couple months tuning, then decide I’m not happy and have to rip it apart and do it over. I think this will be a better set-up. It should run better and should make more hp.

 

Yes...I went back and forth on it but now that I've decided on 24 injectors I don't have the ECU capability without going to 3 ECUs or 2 motecs and at least 1 ignition expander....and I'm not sure what I'd realy gain for the extra parts?? I should do some more digging on this I guess.

 

Any idea why?

 

I got the first of the cams actually finished and ready to ship to the grinder tonight. 3 to go.
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