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Twin Turbo 1UZ Toyota V8, disappointing power

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Hey guys, been working on a car with a Twin Turbo 1UZFE Toyota 4.0L V8, It originally came in with a twin 2.5" exhaust, no intercooler and running around 10psi and was making 250-260rwhp.

Have since changed to twin 3" exhaust, Front mount intercooler with custom over the radiator end tank and custom forward facing intake manifold and with 18-19psi got it up to 375rwhp. resonable gains but still seems low for this size motor on that level of boost....

Not had heaps of experience with these engines but I would have expected at least 500rwhp.

It is running a old EMS stinger ECU, TH400 gearbox and 9" Diff.... on 19psi its running with 19 degrees of timing in the top end. Even with more timing I can't see it jumping over 100rwhp. AFR's are 11.7:1

I guess I'm just a little stumped... going to do a compression test tomorrow to see if there is any issues with the cylinders/valves, supposedly only 10,000k old motor

Attached Files


Nice work there.

What turbos are those?

Have you measured turbine inlet pressure?

That looks really good viper!

In stock form the 1UZFE heads and cams are a big restriction and my own experience with these is that they don't tend to produce the sort of results you might be expecting once you add boost. Of course the results you are going to see will still be dependent on the turbocharger sizing too. As TTM suggests it would be nice to know what size turbos you're running and what the turbine inlet pressure.

UZFEs can be made to produce good output but there is a bit of work involved. I suggest you take a look at Lextreme

They are a pair Of "ITS Street Heat 57" turbos, basically T3/T4 hybrids


Did a compression test and all cylinders were around 210psi, all plugs looked good... Checked Cam timing and was lined up... Base timing was a touch off but nothing to cause too much power loss.

So was 330rwhp on 15psi and went to 375rwhp on 19psi so about 11rwhp per psi... Does that seem about right?

What sort of timing would you roughly be expecting to running on a N/A compression motor with 19psi?

Its a Auto and on the dyno it flashes up to 5000rpm so my runs are pretty much only 5000-6000rpm. I would imagine the stock Cam would be designed to have power between 2000-5000rpm so is it possible just a completely unmatched setup... The owner keeps going on how his mates car with a similar setup makes near on 700hp tho

He says his mate has pretty much the same combo except no intercooler with E85 on 30psi and makes 670rwhp, If the power continued to raise 11hp per psi that would still only put us at 500rwhp...

Pretty strong motor if they can handle 30psi on stock internal tho!

I've been told that automatics are funny on the dyno, and sometimes, you can lose up to 25% of your power at the wheels because of them. I believe this is non-lockup transmissions. Superflow actually tested this and found it to be true.

You should get it on the dyno and try throwing a degree or two more advance and see what it picks up. You never know, there may be a lot

left on the table. Very cool build tho, nice clean work.

I would be wary of trying any comparison with an engine running on E85 - It's usually night and day.

I'm actually a little surprised you can get 19 deg into the engine on pump gas with 19 psi boost. The handful of FI 1UZFE engines I've tuned were heavily knock limited on pump gas. Put this into perspective and 30 psi with a fuel that allows the ignition to be tuned to MBT would see a massive increase in power.

If the converter is somewhere in the 5000 rpm stall vicinity I'd say that's way too loose for that setup. With a relatively small turbo package on that engine you should be able to get away with a pretty tight converter.

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