Buying an mr2 turbo - advice

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tommy10101
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Re: Buying an mr2 turbo - advice

Post by tommy10101 »

Which mods would you suggest for the few easy gains?

I bought the rev3 btw and loving it so far. Light weight clutch takes some getting used to :blink:

I will get it on a rolling road and report back it’s numbers

So far it has HKS induction, Powerflow cat back exhaust, blitz bov, KW coilovers, light weight clutch and flywheel



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Re: Buying an mr2 turbo - advice

Post by tommy10101 »

i think most of these mods were done in Japan before import
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Re: Buying an mr2 turbo - advice

Post by SonicSW20 »

Full service first + timing belt if it needs / age is unknown, compression test, leakdown test. You want to make sure the engine is in the best possible health before doing power adding stuff.

If its date of first use (not date of first registration in the UK, first use in Japan) is 31st July 1995 or earlier, then a decat will pass an MOT with no issue if the tester does their job properly. Stay away from the cheap ones on eBay, I'd recommend BRD's one or TB Developments, both make a decent decat with a flexi and mounting bracket that won't crack. Hopefully the powerflow system just bolts onto the stock cat without modification at the moment. I have seen systems like that where they also replace the flange on the cat (perhaps it was rusted), but with a non stock size or not stock orientation, which means that other exhaust systems or decats won't fit anymore.

Before adding any boost, upgrade the intercooler. The stock one is barely making it as. The generic ones are better than stock by quite a margin so you don't *have* to spend big money, but make sure you check the quality of the product before installing - cheap ones may have bad welds. There were some great aftermarket options in the past like Phoenix Power (largest core that fits in the stock location), but thats long discontinued.

Boost controller - as long as the engine is healthy and you have a better intercooler, freed up the exhaust with the decat, a boost controller can add quite a bit of power even with the stock ECU. Around 17psi boost will see you to ~270whp or so and is within what could consider "safe" on a stock Gen3 ECU.
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Re: Buying an mr2 turbo - advice

Post by MR2DI4 »

The easy gains put simply come from more boost, however don't do what I did and looked at the fueling LAST you need to look at the fueling FIRST. My advice is as follows:-

1. Get a fuel pressure gauge fitted and verify your base fuel pressure and that the 1:1 FPR is working as it should under boost. The fuel pump could be old, they loose pressure as they age and replace the fuel filter. The fuel filters choke solid, not as you may think from stuff floating about in your fuel but from the carbon brush wear from the fuel pump. I opted to boost the Voltage to the stock pump but either fit a new pump if the pressure is low or upgrade the pump and fit an adjustable FPR so you can set the fuel pressure at the maximum spec that Toyota recommends.

2.You need to disable the factory fuel cut. After this point you car is no longer "Idiot Proof". You need to be running premium petrol and decent engine oil and also your coolant system needs to be clean. Every increase in kW you make at the wheels is now another kW into your cooling system that it has to cope with. Unless the engine has always run coolant and the cooling system is spotless don't even think about more power. It goes without saying your engine needs to be in good shape, compression wise etc.

3. Up the boost using either and electronic controller or a MBC like I used, so much easier to fit and adjust and 90% as good as electronic. Electronic or MBC is going to make no difference to your top end power, you may loose some midrange in higher gears as the electronic has the ability to hold the wastegate closed for longer. You now need an AFR guage to raise the boost to the point your staying in 12:1 or richer under boost. Run leaner at your peril.

4. There is nothing wrong with the stock intercooler. I did extensive testing with a temperature sensor in the throttle body and logged it. Where it falls over is the side mount location is CRAP it doesn't matter what you fit it needs a massive fan. I put a huge SPAL fan on it, custom shroud and made a boost controlled switch that kicks in this and the hood fan at anything over 5psi of boost. Problem solved. There are several reasons why I did not change the intercooler from the ducting to the stock IC and its internal volume that needs to be pressurized under boost or you get lag. with just bolt ons your wasting your money changing it as the power gains are minimal. Sure if you want 350Hp plus then it goes in the bin

5. There are gains to be made in the exhaust however its a compromise, more power = more noise. I stayed with the stock exhaust for several reasons but tossed the CAT in the bin and fitted a 3inch downpipe. The gains here are more from the weight saving and heat source removed from the engine bay and generally making the engine easier to work on and better airflow through the engine bay. Unless your old cat is blocked, it makes no difference. The honeycomb in mine was gray and it had no blockages or buildup at all.

6. There are further decent gains to be made from headwork and port matching. On old engines I have worked on the top end power increase was noticable after a head rebuild. The big problem with old engines if the crud that builds up on the back of the inlet valves in particular. This totally stuffs the breathing, seriously one I worked on the back of the valves looked like a "Cone" instead of a nice curve surface to a near flat. Not only its resrictive its stopping the directional flow and swirl of the gas into in the cylinder. The rubber valve guide seals are long gone and the inlets suck in excessive oil, especially if the valve guides are also stuffed.

As you already have the CT20b, the hard work is already done. Pretty much the only reason the Gen 3 makes another 20Hp stock is the CT20b over the CT26 running a couple more pounds of boost. Sure the cams are different and there is more valve lift but a big chunk of the gain comes from the turbo running more boost stock. The Gen 3 has bigger injectors and has more scope for bolt on gains.
Last edited by MR2DI4 on 27/11/19 0:25, edited 4 times in total.
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Re: Buying an mr2 turbo - advice

Post by SonicSW20 »

Why does he need to disable fuel cut? He has a Gen3, fuel cut is somewhere around 18-19psi stock. It would be stupid to disable a safety for no reason.

The stock intercooler is rubbish, you seem to be the only person who ever recommends keeping it. Any difference in lag is negligible.
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Re: Buying an mr2 turbo - advice

Post by MR2DI4 »

Sure Toyota put in a rubbish intercooler then ran the same one for all revisions for 10 years without the need to change it.

I have done the testing so no point trying to argue with me. Have owned the car for 20 years and I'm still looking for someone who has done a base dyno run, then done another run with the only change being the intercooler and provide an honest comparison. To many myths get perpetuated on the net, the stock IC being rubbish is just one of them.

Just for perspective sake, even then a Dyno is not real world driving or power. My dyno run before the huge SPAL on the stock IC had mains powered fans at the front of the car and a mains powered fan blasting in the side intake for the intercooler and the engine hood up on the strut . I would suggest that a real world "Worst Case" dyno run would have NO MAINS FAN assist into the intercooler side vent and the hood down. The natural airflow in real world driving into that side intake is truly pathetic and was proven on runs on the road with and without the stock IC fan running using the temperature logger. Even the stock fan as small as it was and where it was mounted made a significant difference in peak air intake temperatures under full boost. My conclusion is that is was perhaps an omission from Toyota not to have the engine ECU trigger the fan ECU using the turbo pressure sensor signal into running while your over 5psi of boost, sure it would reduce the life of the fan but hey. The intercooler on the road relies on you NOT being on boost for the majority of time so it allows it to cool. Once on the track however your in potential trouble. Track time here was pretty much two speed swapping between 3rd and 4th gear unless you stuffed your lines and had to drop to 2nd. Actual road speed in 3rd is pretty low and your spending a huge amount of time on full boost so pretty much any side mount intercooler without a great deal of fan assist is going to heat saturate (note I never used the words heat soak, to much BS on the net about this including your IC heat soaks at the traffic lights). What your relying on without a fan is the thermal mass of the IC and enough time off boost for it to cool. The SPAL fan I put in moves more cubic feet of air through the IC than the engine is using at the redline.

By all means I'm interested in hearing the actual performance gains from anyone who ONLY changed the IC on an otherwise stock car. You can find the information on the net as to what percentage gains can be made from temperature/air density and its not huge, especially when your chasing the law of diminishing returns as heat transfer rates are based on the temperature differential so the closer you get to ambient the exponentially more difficult it is to drop the intake air temperature. Bottom line is your not really lowering the intake air temp for gains alone, your also doing it for safety in reducing the possibility of detonation.

The conclusion I arrived at was there was nothing wrong with the stock IC, it needed some supporting mods similar to other areas of the car if you want to go upping the power.
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Re: Buying an mr2 turbo - advice

Post by SonicSW20 »

Every MR2 specialist / tuner I know of disagrees with you about the stock intercooler.
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Re: Buying an mr2 turbo - advice

Post by tommy10101 »

Just spoke with Rogue motorsport on the phone, I am going to ask them to keep the car for a little while and look at the below.

Try clutch, advise on juddering. Is it normal? Can the biting point be raised?

Service - change all fluids, (not cambelt water pump, already done)

Compression test, leak down test

Check whole car for rust and repair anything major, plus add protection

Suggest suitable mods to enable safe 280bhp (inter/charge cooler, boost controller, decat?)

Hopefully all that won’t be too expensive. And lightweight fly, i am concerned about excessive juddering. Might be normal as never driven one before but want to check as it is excessive

Thanks for the replies
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Re: Buying an mr2 turbo - advice

Post by TonyleFrog »

tommy10101 wrote: 27/11/19 17:59 And lightweight fly, i am concerned about excessive juddering. Might be normal as never driven one before but want to check as it is excessive
See my post here - https://mr2oc.co.uk/forums/41/165406.html
No juddering whatsoever.
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Re: Buying an mr2 turbo - advice

Post by MR2DI4 »

SonicSW20 wrote: 27/11/19 9:49 Every MR2 specialist / tuner I know of disagrees with you about the stock intercooler.
Since when are you going to receive unbiased advice from a specialist or tuner ? they are making money from you by selling you stuff you have no idea is better or worse unless your prepared to test it yourself.

The problem with just a few bolt on bits is your not really "tuning" the car anyway your just playing with it. The gains are minimal and the stock parts are almost good enough. I will admit its probably easier to swap out the IC than modify the stock one the way I did, but I guarantee that if your using one of those sh*t Chinese rippoff Greddy IC's with no fan its way worse than my setup. Buy yourself a multimeter with a max/min peak hold function and put a bead temperature probe into the throttle body airstream and throw the meter in the boot and take the car up a long incline under a hard 3rd and 4th gear pull at full boost for as long as possible and look at your peak temperature relative to the ambient air temperature. Your probably going to get a nasty shock.Then idle the car for a long time and see what its drops to, you will be surprised how high the intake air temperature is even at idle, its nowhere near ambient.

I say your only playing with it because you fundamentally cannot tune the stock ECU. Your "Tuning" consist of adjusting the boost and adjusting the fuel pressure which is pretty crude and limited. Too much fuel pressure on mine and the engine hesitates as the fuel pump relay switches over from suddenly getting to much fuel.32psi at idle with the FPR vac hose connected is pretty much the maximum.

Fantastic car but the reality is I have kind of moved on, probably an age thing. Given the choice I tend to go for the Subaru 3.0R 6MT wagon to drive these days and am eagerly awaiting the release of the new "Global Platform" Subaru WRX STi in about 2021 if they don't fu*k it up.

Found this the other day, lots of good stuff here and dyno results as well if you want to start getting serious about more power.

http://www.koracing.net/viewarticle.php?article=6
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Re: Buying an mr2 turbo - advice

Post by SonicSW20 »

If so say so. :rolleyes:
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