308 V12 conversion begins

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I can plug anything you find into the software and see. I went as far as 118 LSA and down as low as 100 and got nothing but bad results. I’m starting to thing the car companies are selling bunk with the variable time stuff.

I’ve read a lot of stuff from tuner type places that say roll the cam this way for low end or that way for better top end, but I’ve never seen it work. A buddy of mine does flow work and a lot of Harleys. In putting together his kit he bought I think 12 or 15 cams with the timing moved around in 2 degree steps and it did exactly what the computer said it would. Rolling 1 way chop top end power with no low end gains, moving the other way chops low end with no top end gains….when I said no gains, he got 1% to 2% gain at the expense of 3ish % on the other end, and once it was 4 degrees out of position there was less power everywhere.

I think the simple variable valve timing systems are designed to reduce emissions with increased LSA preventing fuel from escaping out the exhaust at pollution test loads, then they roll the cam back to the correct location to make power…..at least that’s how it looks to me. One thing I can’t get off the computer is I think big cams may be smoother down low and idle better with more LSA which might make it a better mannered driver…I’ll have to think about that one.

The BMW, and Ferrari systems change the valve lift and duration and then change the manifold tuned length to match, doing that on the computer I see some improvement down low, 10% ish….but I have no clue how I would change the valve lift and duration

I've seen lots of 2v heads outflow 4v heads too. Air prefers 1 big hole to 2 small ones because there is less total perimeter. The problem is that 1 big valve needs to open a lot further than 2 small valves do, about twice as far. To do that, you either have to move it twice as fast which just hammers the valve train or you need to give it more time (duration). Generally you find they do some of each, with a 2 v engine running about 20 degrees more .05 lift duration than a 4v engine for any given rpm range. The extra duration makes the engine a little less efficient and harder to pass emissions with.

A 3 valve makes quite a bit of sense since the exhaust valve is already significantly smaller than the intake, so there is much less to be gained by putting in 2 tiny ones. Something like 75% of the advantage of a 4v comes from the intake side, but it’s only ½ the cost increase of going 4V.

 

My car looks like in needs a paint job

Yes, I bought it oh, 7 years ago from Fred Hooper.
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Since the computer keeps say "it's all about the flow stupid", I ordered a buch of stuff to build a flow bench. Now just I need to find a scrap TR head to practice on.

 

no...i just sold everything I had in the basement that wasn't nailed down very well

I think the GTO front end makes it look lower than it really is, I only droppe it about an inch, just enought omake the wheel/tires look right in the wheel wells.

 

Thanks. It's a 10-15 foot paint job, the sun has taken it's toll over the years. The wheels are 550 and it's also got spring and shock work so it does handle pretty well.

 

The car makers are getting very clever these days......

I saw a SBC pick up 150 hp switching from 1.7 rockers to 1.5 rockers on the exhaust….the guys had way over ported the exhaust and limiting the lift to restrict the exhaust flow down to where it belonged worked and absolute miracle. I've seen absolutely bizarre stuff work well on restrictor plate race engines. As far as rolling the cam, on any engine that is set-up properly with head, intake, exhaust flows all matching the cam rpm and compression it just seems like there is a right spot and everywhere else is wrong. I think once everything is matched up right then the cam is either right of wrong within a couple degrees anyway.

I think for this project, I’ve already bitten off more than 1 winter is going to let me handle so I’ll just be happy to get it running with any cam timing and intake length

 

I've never seen those.

I was talking to a head guru years ago about an engine I was doing and he was going to do the heads. The factory had just come out with new oval port design vs the round ports that I had, so I asked if I should get a set of the new ones for him to work on because I wanted the best (I was young and this was my race bike after all). This guy did all the porting for the factory race team and he told me “the air doesn’t really care what shape the port is, I port the old factory heads to 138 and I port the new factory heads to 138 and both bikes make 95 rwhp. I have no idea why they changed them, but it doesn’t add hp.”

I wonder if the new tall ports work better with a dual plant intake? That’s all I can think.

 

I think you hit the nail on the head when you said the ports are no longer paired....they may have needed the odd shap to make that work out.

I actually thought about criss-crossing everything to lengthen the runners, it’s not a bad idea and can still work with the ITB set-up. It would pull the lower rpm torque up, but would cast high rpm power. A big wide torque curve is really nice, but so is a bragging rights hp number……oh the decisions that need to be made….

 

I just got the shipping bill for the engine....ouch.

The good news is it's now leaving CA and will be here in 9 days or so.

 

Well stop by Bill! The engine will be here in 9 days or so, I'll be working on the TBs and flow bench until then. I've decided to not build the intake until I have a port design worked out so I know what shape to put in the manifold.

do you still have the paint boost???? I've got a 308 just dying to be painted

Of course you need a lathe, I can’t understand how anyone would question that. The next thing they’ll be trying to tell you that you don’t need a mill to go with it

I built a flow bench years ago...but then I was seduced by the dark side (boost) and no longer saw a need for it and sold it. Now that I’ve returned to the path of light and goodness (as Russ would say), I need a flow bench again I think. A couple manometers, a shop vac or 2, a little PVC pipe, and a table or bench to bolt it all to, that’s all there is to it really. To measure gain or loss, it doesn’t even need any kind of calibration, but I guess I should make a couple calibration plates too so I can put actual flow values to the numbers so I know when it’s good enough.

 

That is a completely bizarre port. Is it the pushrods coming up that dictated that shape maybe???

 

I got a little done this weekend. I started building a flow bench to play with the heads. I'm nearly done, I still need to make calibration plates, a cylinder/head adapter, run some hose to the manometers, and calibate the slant manometer.

I bought red fluid for the slant manometer to match what came with the u-tube manometer and learned that was a bad idea...the red fluid is basically kerosene I think and has very low surface tension making it sit in the meter tube at a horible angle so it's very hard take a reading. I'll replace it with green fluid, which is basically colored water and will sit nearly square the the meter tube in spite of the angle the tube sits at.

any way, I should be ready to start baselining the TR heads in a couple days. I haven't found a junk head to practice on yet, so I'm going to try taking a rubber mold of the ports and combustion chamber and then see if I can make an epoxy casting that flow like the original. Then I take try anything I please with no worries.
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