V-12 Engine into 308 Build, over on Grassroots

Thankfully you noticed the leak preventing any “flamethrower” action! So close to starting, very exciting!


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Pulled the manifold off and didn't really see the smoking (or leaking) gun but o-rings didn't look great so I ordered all new, be here Wed. In the meantime I'll get everything cleaned up and ready to install and maybe have another look at the tach.

 

Back to when I was cranking the engine to prime the oil pump and noticed I had like 10psi oil pressure and thought it fine....but then noticed I also has around 10psi fuel pressure with the fuel tank empty and pump off. Last night I discovered that the pressure transducers read just fine on the bench but when they are installed and the chassis grounded they have a 0 offset...270mV on the oil pres and 330-370mV on the fuel as it drifts around 30-40mV. These are 2 brands from Amazon, as typical chinese stuff they look the same other than the marking on the casing...both are junk it seems. I'll try 1 more where a couple reviews specifically mention no/low offset for fuel (don't care about the exact value for oil as long as its reading something so I know there is pressure and I can remove the offset in the ECU easily) before ordering a $200 Honeywell version cuz I do need to know fuel pres to calculate the correct mixture

 

I've had very good experience with these,
https://www.te.com/usa-en/product-CAT-PTT0028.html

Mouser, digikey and I think Newark should have them. Normal go-to is mouser.

MS is now TE. Price point similar to Honeywell. From what I've read TE is better suited for the automotive environment.

 

Yes, I was looking at something very similar
https://www.digikey.com/en/products/detail/honeywell-sensing-and-productivity-solutions/PX3AN1BH100PSAAX/5878260?s=N4IgTCBcDaIA4A8DMBDAdgRgEYAsMAZ8QBdAXyA

They both even use the connector I already have, but both are 1/4NPT instead of 1/8. I just had to add a 45 elbow to the oil so if I could get to it I could change it for the new sensor...but even manifolds off reaching it isn't easy. On the fuel, adding a kludgy looking adapter is a no-go so I'd need to retap the port.....hence my overring 1 more Chinese sensor just to be sure the rework is needed

In other news I decided to try 3x8mm lower o-rings instead of the standard 3x8.5mm on the injectors to make assembly easier. The plan this time in rail end in the rail, then pop the manifold ends in....I think that is how I did it before to avoid the fuel side leak risk but that makes the lower o-rings REALLY hard to install without pinching/cutting so these should help at the risk of a mild vacuum leak I suppose. The rail o-rings are coming today so assembly/test tonight hopefully.

 

Stupid question.. are you using any grease on the injector o rings? I've never been able to get them to insert dry without problems. Since I've usually got a tub of Gibbs open during assy, I use a bit of that on them. Slips right in. STP has some old school lube, works fantastic but dang near impossible to remove if you need clean up, like anti-sieze!

 

Right, dry is flat impossible on this setup. I have been using WD-40, but noticed the rail o-rings get pretty stuck on removal so this time I pulled out a tube of silicone grease to try

 

I've used Wurth HKS oil on fuel o-rings with good results; BG also makes a nice light silicon lube that works well too.

 

The new fuel pres sensor is much better, 71mV offset and seems stable. The oil pressure still reads 0 with the 270mV offset so it appears stable and I'll call them both good enough.

The manifold o-rings came yesterday, I bought 3x8mm instead of the standard 3x14.5mm to make it a little easier to assemble and they seems fine. Just waiting on UPS to bring the rail o-rings now. The plan this time is make sure the injectors are seated in the rail then pop in the manifold end because the fuel needs to be sealed but a small vacuum leak doesn't really matter so I want all the risk shifted to the manifold end as best I can.

 

You guys are using lots of trigger words, Dear Penthouse Forum, today I fingered some lube for some tight O rings

 

Car porn.

Well...its almost sealed this time. It looks like a mist coming from 1 injector on the end. Hopefully 3's a charm.

 

This is a challenging assembly. I didn't have room for 2 fuel rails or to assemble the rail to the TBs then drop the assembly into place so assembling relies on everything flexing enough to pop into place.

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I decided the rail wasn't sitting just right and was torquing against the injectors so I sawed the end off and repositioned it a bit....and then there was fuel pressure.

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I put the plugs in then spent some time trying to get the boots to right right and the wires resembling neat

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As long as I was making stuff a bit neating, I gorilla taped over the hack job I did on the stacks so they at least look right even if they aren't

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oh yeah, then I started it....a little....on staring fluid. I'll give everything a good look over and spend some time with the log now and be share everything there looks right before another go.

 

Sounds good. That cam profile has a unique sound I recognize
High rpm it'll scream

 

Right, if I'm not mistaken you worked on an engine with ALMOST as radical cams

 

Yup, a couple actually... Let's see..
4L NA monster
3.5L QV NA
QV supercharged

Your build sounds closest to the 3.5L build. Oddly, as the 4L has ITB trumpets... But it's also sporting a massive custom tri-Y exhaust currently open so it's stupid loud. Once tamed with a muffler it'll be interesting to see how it sounds.
Valved exhaust though with that cam profile really makes a 'bark'. 4k and up just howls.

The 3.5L was fitted with a valved Capristo, custom headers. But stock plenum so there was this constant sucking whistle. The supercharged QV is sporting the same exhaust but I used the custom manifold with a monster oval 2k CFM TB.

 

Mine are large tri-y headers as well. 4 mufflers, 2 are loud 3" race mufflers good for about 800hp, the other 2 are 2" hotrod mufflers good for maybe 150hp eacreach and not TOO loud for normal driving. The valves are wired open for now but the ecu will control them at some point.

 

I've got to dig up some audio video files on the 4L engine. Now where did I put them?....

 

You tease. Posts like this need a Love not a like button. Look forward to hearing and seeing more. How long ago did you start this whole project?

 

way cool Mark. Keep cracking.

 

Really nice job Mark!

 

Im so looking forward to your machine completely dialed in !! Everytime I see a new post on this thread, I get so excited !!! I have my fingers crossed, and pulling for you Sir.

Thank you

 

Running , 6-7k, idle around 2k, pretty rich so a lot of tuning to be done

 

14 year last month.

yeah, I know.........

 

Sounds good, real good.
Yeah, that sounds like the big 4L but with more pops like an entire bank more

You need a key man... I get Nick to run start/stop and leak checks while I'm manning the PC.. real time tuning keeps you on yer toes. Rolling cart, folding chair right next to the engine bay. I'm assuming your ECU has a kill switch hot key, can't tell you how many times that had come in handy.