Have you guys looked into any of DOA's parts.

http://www.doaracingengines.com/v6.html

I don't care how fast my V-6 is, it is for rockcrawling only and my power comes from my Marlin duals at 208-1

Is this because of the other things that you have done? Or is your engine special?

Just looked at the DOA website. They are claiming 33hp by simply porting the heads with stock exhaust. That is a big gain if the exhaust is the limiting factor. If it were then they would not see a 22% increase in power with stock exhaust.

I wonder what it would do with the bigger valves?

DOA is claiming 225hp out of their longblock. I can only assume that this means that I am bolting stock everything else onto it. That is rule of thumb for crate motors unless they specify carb size and headers etc.

I am going to look up some headers and see what they claim for hp increses.

>>>*Morning!

*I just spotted this thread. Le' and I are getting ready to wander off for a short few days of sanity recovery, so I thought I would chime in.

I have been looking at the 3VZE, and the more I look the more I wonder why?

The design is odd, the airflow is inefficient, the engine is heavy and hard to get to to even work on. I was looking for a reason for it burning valves from time to time on #5 & #6, and my heat gun showed some spooky looking exhaust gas temps. Every time we see the exhaust manifolds they are warped beyong belief.

Restrictions. No doubt. So looking at the heads, they are easy to free up. I realized instantly that the engine needed a bit larger valves, so I went and had some made. That turned out to be cheaper and better than buying stock ones.

All one needs to do is pull an exhaust valve out and look at the seat and port. What were they thinking? I looks like they cast the head, then decided to use a smaller valve afterwards. My best guess was they built the engine, then realized it had more RPM potential than they wanted, so they took the easy route to choke the thing off..it couldn't have been for improved mileage, that doesn't work. Efficency is what improves mileage.

For a long time we were seeing these mostly for head gasket/valve problems (heat, not the gaskets...), now we are starting to see the engine more and more as they get older in the fleet. Rebuild kit prices plummeted this last year so that helps, suddenly it is in a typical budget to rebuild one.

So far, larger valves combined with port changes and a better exhaust seems to add a nice 30-35 H/P easily. The short block just needs to be snug. Adding a cam is a can of worms, the upper end valve train dictates lots of changes. I even thought of having the valves made .030" longer to leave room to regrind and add lift/duration but it hit me quickly that this would restrict the cam choice to fit the valve.

Besides, the factory got very close to correct on the stock cam design for what my opinion is worth, when the goal is to just drive. I do see that some folks are offering cam setups, way ahead of me there. Fine if in the budget but the amount of work didn't look worth it to me. I will bet that soon some suppliers will be offering new stock base circle cams for these.

So like all engines, she responds to airflow. Free up the intake and exhaust, bit of port and valve improvement, and I see a nice 20% plus gain in there.

So far Tod has only done a half dozen or so but it seems to work real nice, I agree with Tim over at DOA. There is 20-30 easy ponies in there, much more gets you reaching deep in the jeans for the hardearned......*EB

That's interesting! If your guess is right maybe that was Toyota's way of putting a speed limiter on the truck. That could possibly save them money on warranty claims by discouraging racing the motor.

30-35 hp gain, that sounds awesome! Maybe I will see that on my truck when I add headers a couple more months down the road. I already have full exhaust besides headers, and I just bought a K&N. I have ported the heads and put bigger valves in my motor I am building right now. Damn, now im excited!

So how do you go about getting bigger valves? Do you just pull off the head and have bigger valves put in? How much bigger?

That's interesting! If your guess is right maybe that was Toyota's way of putting a speed limiter on the truck. That could possibly save them money on warranty claims by discouraging racing the motor. [/quote]
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>>>*Maybe, and I do concede it is still a guess on my part. I can usually tell what a port will do with my fingers, and that port restricts. The reason they did it beats me, but we can fix it.
*Seems to work, still experimenting. I am just getting involved in the design. *Same rules apply though...*EB

Thanks for pointing out how I didn't improve my engine like I easily could have for just a little more money when I had the valves done. <img src="/forums/images/graemlins/lol.gif" alt="" />

Dont you think 1mm is a bit small for a valve increase on these motors? Dont you use the stock seat at just 1mm oversized? When I got looking into the head I noticed that the exh valve seat was quiet a bit smaller than the bowl but that was not the case on the intake side. I was thinking that increasing the seat size to mach the bowl would be better but that would take 2-3mm over sized valve right?

7mm difference between intake and exh valves seems like a lot but I havent bothered to measure these kinda things on any other motors I have worked on.

I asked on the other thread about any sort of industry standard when it comes to the ratio of exh valve to intake valve size? Is there any reason we couldent use an intake valve and seat in place of the exh valve? Would it work with the engine dynamics barring any clearance issues with water jackets in the casting?


Averkam....
The larger than normal gains on exhaust work I think are due to porting the heads and intake along with cams and headers. once that was all done everything was flowing better except the actual exhaust tubing it was still stock 2" w stock muffler. Once that was opend up it allowed everything else to do its job. I cant wait to have my throttle body bored and cut up a manifold to see what can be had in there.

That makes more sense. I did not see that you already had the heads freed up. That may be why you saw the dif and others do not.