Advice on what power to expect

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mickybo
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Advice on what power to expect

Post by mickybo » 07/10/19 22:01

Hi guys, just got my build done, rev 3, forged engine, mamba gtx3071r turbo, 800cc injectors, w/m injection, link g4+ and lots of other usual gubbins, but tuner can't get mot than 300bhp on fuel alone and 350bhp with meth injection, and to be honest I would be expecting 350 on fuel and over 400 with meth or are my expectations too high, running 1.7bar on the turbo



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Re: Advice on what power to expect

Post by benckj » 07/10/19 23:18

IC, exhaust & other mods?
May need adjustable cams to help dial in as well. Are AFR’s decent and ignition advance ok without knock? Much of the high power comes from ignition tuning but has to be done with care.


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Re: Advice on what power to expect

Post by mickybo » 07/10/19 23:29

Yes uprated intercooler, full turbo back exhaust, apexi intake, running about 15° advanced on base timing, stock cams and gears, granted over here in Northern Ireland can only run 97 fuel as can't get 99 here, just I've read threads about people making over 400 with less work than I've done, AFRs are good running 95% duty on the injectors, have a 355ltr fuel pump

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Re: Advice on what power to expect

Post by MR2DI4 » 08/10/19 0:47

Probably would have run smaller injectors myself and the move to Dual Stage injection is better.

Cams also play a big part but with fixed rather than a variable system that a modern car has its a big compromise whatever you do. You can shoot for top end but your bottom end power will dive.

I still believe a big part of gains is improving the flow and this involves some very time consuming work done by hand that most engine re builders are simply not going to do due to cost. Things like port matching and polishing in the head. I spent a whole day just cleaning up the flow and port matching the stock cast iron exhaust manifold, it was WAY out. Didn't even look at the intake but no doubt the throttle body to the head is also pretty bad.

I'm really not surprised at the power, we had someone else here in NZ some years ago who spent a fortune on a rebuild and only managed 200kW. Hardly worth the effort when a bit of basic stuff got me 170kW on a 1990 GT and I didn't even get into any head work. Cleaning up the valves and some basic head work would give me another 10kW. The stock ECU and injectors are pretty much all but maxed out anyway so not really worth the added effort. If I was prepared to change from the stock exhaust and went all out on the head i would expect 190kW.

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Re: Advice on what power to expect

Post by shinny » 08/10/19 12:17

Are you talking about power at the wheels or at the fly?


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Re: Advice on what power to expect

Post by mickybo » 08/10/19 12:30

Fly, its on a dyno dynamics roller,

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Re: Advice on what power to expect

Post by SonicSW20 » 08/10/19 13:12

24-25psi on a GTX3071R (even though its a copy) and only making ~300bhp estimated flywheel - something is wrong there.
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Re: Advice on what power to expect

Post by mickybo » 08/10/19 13:18

That's what I thought, from what I've read 500bhp is possible on stock head, it's the exact same turbo as a kinigawa and have an uprated forge actuator on it. But tuner tells me 300 is it on fuel as anymore it starts to knock and 350 with meth injection even though its not knocking doesn't want to push it too much. Am I missing something or is this it as I'm about 7k in parts at this point

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Re: Advice on what power to expect

Post by jimGTS » 08/10/19 16:38

have you check mechanical timing?? cambelt being a tooth or 2 out can cause restrictions.
boost leaks?

it is well below what it should be making, 95% duty on 800s at 300crank is odd for sure.

either mechanical issue or bad tuning IMO.

as im sure you know plenty of people running gen3s have tipped over 300crank with breathing mods at 1.2bar on a stock turbo.


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Re: Advice on what power to expect

Post by mickybo » 08/10/19 21:20

Which is why I'm baffled. I was making 280 before the rebuild with stock ct20b ecu. Is it the 97 fuel, will 99 make that much difference

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Re: Advice on what power to expect

Post by jimi » 08/10/19 23:03

You could try an octane booster, see if that makes a difference
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Re: Advice on what power to expect

Post by benckj » 09/10/19 1:49

With 97 and WI octane won’t be an issue. I’d say the Tuner is being very conservative with ignition map having seen knock in upper range. Your EMS is not great at knock detection and most Tuners I know will trust their judgment more and turn control off. This is where experience with the 4 pot motors pays off.

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Re: Advice on what power to expect

Post by MR2DI4 » 09/10/19 3:12

jimi wrote:
08/10/19 23:03
You could try an octane booster, see if that makes a difference
What a hassle, if you cannot just drive into a gas station and fill up whats the point ? we got 98 over here at the pump, no need for anything more.

What did they do with the compression ? probably want to decrease it with a thicker head gasket to get more fuel/air in the cylinders and decrease the knock. Sounds like your running to much compression.

Tuning alone is not going to fix it, it's all about the meticulous engineering and getting it right to make the power your aiming for. A forged engine does nothing for making Hp, all it does is support making more Hp, its all the other work needed thats starts getting really expensive. I don't know of anyone in this country capable of doing the work required.

Shows you just how good the stock Toyota ECU is and the CT20b or a hybrid CT26 in good for over 300Hp. Its a really old motor design now without Variable Valve Technology so really I wouldn't go chucking a load of money at it. I'm blown away the difference VVT makes, its like having a low boost turbo and its only a NA car.

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Re: Advice on what power to expect

Post by jimi » 09/10/19 3:58

MR2DI4 wrote:What a hassle, if you cannot just drive into a gas station and fill up whats the point ? we got 98 over here at the pump, no need for anything more.
The point was, it's a quick way to get answer to his question
mickybo wrote:Is it the 97 fuel, will 99 make that much difference
given the fact he lives in Northern Ireland and
mickybo wrote: granted over here in Northern Ireland can only run 97 fuel as can't get 99 here
I wasn't suggesting he run it all the time ;)
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