Boost controller for more power?

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Boost controller for more power?

Post by Sonac » 11/02/19 22:00

So after my father owning several MR2's growing up, I have always been a big fan.
And now I'm finally able to buy my first 2.

I have put down a deposit on a 1992 rev 2 turbo. Picking it up hopefully next week.
Its already had a 20b swap so the turbo is great. Very well looked after.

My question is on power. Stock it makes 220. Not sure how much it makes after the 20b swap.
It has no boost controller though.

Will adding a boost controller allow me to make more power without a tune? I assume I can just set the controller to 18psi or something and get me some 270bhp action right? I know I can't get much more than that without upgrading some bits. I'm fine with around 270.

I'd love to be educated. Cheers.



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Re: Boost controller for more power?

Post by TonyleFrog » 12/02/19 0:29

A stock Rev 2 runs a CT26 turbo with 440cc fuel injectors.
On the Rev 3 Toyota changed the turbo to the CT20b and 550cc injectors.

There is more to the power game than just turning the wick up on a boost controller..
You'll also need a more free flowing exhust and better intercooling for reliability.
Have a read of this - https://www.mr2oc.co.uk/forum/41/160603.html
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Re: Boost controller for more power?

Post by MR2DI4 » 12/02/19 0:41

Your ultimately limited by the 440cc injectors and not the CT20b.

You will get about 250Hp on the Dyno with some other supporting modifications. I rebuilt the CT26 into essentially a CT20b and added a few extra things.

Bigger SPAL boost controlled fan and shroud on the stock intercooler.

Boosted the Voltage to the stock fuel pump with a DC-DC converter to give 31psi at idle.

MBC to give me 17psi to the redline.

Got rid of the fuel cut by making my own FCD, this "Flatlines" the Voltage from the TPS into the ECU to just before fuel cut.

You really need to checkout the fueling before cranking up the boost. I have a fuel pressure gauge, oil pressure gauge and boost gauge with AFR gauge.

Cannot stress enough about getting the right base fuel pressure. If the fuel pump is old its lost a few PSI and thats the extra few PSI your going to need to stop the engine running lean under boost.

You will find at 10psi of boost your AFR is fine, they are designed like that by Toyota. The extra fuel cools the engine and prevents det.under stock boost the AFR is 10:1

Once you begin cranking up the boost that "Rich" condition quickly disappears and your getting 12's and 13's to 1. The increase in power not only comes from more boost but a leaner mixture. This is all good until you force in too much air.

Your engine cooling system needs to be be up to scratch. Every extra kW that makes it to the dyno is also going into your cooling system.

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Re: Boost controller for more power?

Post by Sonac » 12/02/19 13:34

Not sure about fueling but the intercooler and radiator have both been upgraded already so cooling is just fine.

I think I'll install an AFR, Oil pressure and Water Temp gauge before I do any power mods.

Then I'll look into checking the pressure on the fuel pump.

After that if all is good I'll crank up the boost I suppose.

As far as I can tell by what you are saying, as long as I keep an eye on the AFR then I should be good.

Cheers

EDIT: Just found out it already has a uprated fuel pump (Walboro 255 pump). That pump is good for 500hp plus. So really just limited by the injectors.

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Re: Boost controller for more power?

Post by MR2DI4 » 12/02/19 21:12

Yes you don't actually move away much from the stock set-up once you have a CT20b.

Power wise you can get to that of a stock Rev 3 without to much effort.

Mine did a base run on the Dyno and then again on the same Dyno and picked up 25kW.

Its not at 250Hp because there is quite big gains in pulling the head and port matching everything and cleaning up the valves. The valves really do get a bad buildup on them over time and this really has a bad effect on flow.

Still running the stock exhaust with the CAT removed and a 3 inch downpipe fitted. Yes could probably pickup a few more Hp from the exhaust but its a Hp vs noise trade off and I don't like exhaust drone.

I cannot be bothered pulling the head and doing all that work myself these days, the car is old and engines have really moved on. I couldn't believe how much difference in power variable valve timing made until I bought a Subaru.

Get a decent AFR setup and begin increasing the boost in stages and watch as the engine begins to lean out. You can only increase the boost as far as you have fuel to match. That CT20b if in good condition will do 19psi and the injectors will simply not flow enough to support that.


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Re: Boost controller for more power?

Post by rgb » 13/02/19 20:29

stop chasing numbers and just drive faster

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Re: Boost controller for more power?

Post by MR2DI4 » 14/02/19 0:06

rgb wrote:
13/02/19 20:29
stop chasing numbers and just drive faster
Well yes once you have done only minor mods you quickly find you need track tyres.

Both Tyres and brakes need to be in top shape.

Cannot run anything other than Toyo R888's on the stock 15inch rims, its just too fast.

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Re: Boost controller for more power?

Post by Sonac » 14/02/19 1:37

rgb wrote:
13/02/19 20:29
stop chasing numbers and just drive faster
I didn't come here for unhelpful replies. If you have nothing constructive to say, then leave.

In reply to MR2DI4:

Already have a decat and full exhaust system. Sheepdog exhaust if i'm remembering correct. It's single exit.

But yeah with the 20b turbo and the uprated fuel pump I think i'm good for making some more boost. I just want to be careful of those injectors though. I heard of some people blowing their motors because the rev 2 injectors just can't pump enough fuel in. The car leans out and boom.... Damaged pistons.

You think swapping to a Rev 3 ECU, injectors and map sensor would be the best option or just grabbing a plug and play megasquirt? The megasquirts are pretty expensive but I think I could run to it at some point.

Cheers

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Re: Boost controller for more power?

Post by MR2DI4 » 14/02/19 2:10

No you don't need a Rev 3 ECU and injectors, if you get everything else right its more than enough power.

Yes basically you start melting pistons when it runs to lean.

Mine basically cannot handle any more power and you just cannot use it on the road anyway. Did a roll on from 120 to 180km/hr today and its there in a matter of seconds. Throw in a bit of traffic and you can mix it with anything but a bike. Pointless adding more power for anything other than bragging rights, the whole car set-up is wrong. Want more power then sell the MR2 and buy a car that came out of the factory designed from the ground up to handle it. Even if your MR2 made 500Hp, its never going to be a Porsche GT3. Maybe you need to get to age 40 plus before you realise that. :laughing

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Re: Boost controller for more power?

Post by TonyleFrog » 14/02/19 12:53

Sonac wrote:
14/02/19 1:37
rgb wrote:
13/02/19 20:29
stop chasing numbers and just drive faster
I didn't come here for unhelpful replies. If you have nothing constructive to say, then leave.
You're new to the OC so you may not appreciate that being combative and dishing out orders doesn't sit well on here. This is a friendly place and the majority would like to keep it that way. If you don't like a particular post, let it fly away on the wind.
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Re: Boost controller for more power?

Post by notroubleclubber » 14/02/19 17:26

One thing that hasnt been mentioned is the head gasket. If its still on its original then it wont last long increasing the boost.
Change it for a rev 3 headgasket as this is metal layered, the rev 2 one isnt.

I have a rev 2 turbo also and it was standard. Once you start chasing figures you cant stop.

Ive got a ct26 hybrid (same as a ct20b really), st205 chargecooler,walboro pump, rev 3 hg,decat, 3" exhaust etc etc.

Ive studied and studied and studied with what next to do. At the mo im only running 1bar. I currently dont have a afr gauge so dont want to go more than that.
Engine had a full rebuild last year with everything new oem toyota parts. I could have gone forged but i didnt want to.

Dont get mixed up with water temps (you say you have a uprated front rad) and inlet temps. High inlet temps will also make your engine go bang so you want something to keep that charge air cool too.
MR2DI4 swears blind the standard interwarmer and an uprated fan are fine....i beg to differ. Everyone has their own opinions. I went for a st205 chargecooler as it cools the inlet temps fine and is also monitored with a temp gauge with the chargecooler pump monitored too.

So in short, my opinion for your car with the ct20b would be to check the fuel (afr gauge would suffice for this and is handy to have anyway), keep an eye on the inlet temps or at least make sure the charge temp is ok , and then get a decent boost gauge (not the standard toyota one) and just up the boost a little at a time - and dont run the engine on the edge.

If the car has no history then your not gonna know if the head gasket is the rev 3 one so just keep an eye on it. Just make sure it doesnt get too hot and overheat too much as the cylinder walls can and do crack.

Ive ummed and aahed about the rev3 ecu management conversion which would give you bigger injections and get rid of the afm which im guessing is a bit of a restriction. This is an option but unless something comes up cheap enough, im not too bothered bout going that way and just enjoying the car as it is.

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Re: Boost controller for more power?

Post by Sonac » 14/02/19 18:09

notroubleclubber wrote:
14/02/19 17:26
One thing that hasnt been mentioned is the head gasket. If its still on its original then it wont last long increasing the boost.
Change it for a rev 3 headgasket as this is metal layered, the rev 2 one isnt.

I have a rev 2 turbo also and it was standard. Once you start chasing figures you cant stop.

Ive got a ct26 hybrid (same as a ct20b really), st205 chargecooler,walboro pump, rev 3 hg,decat, 3" exhaust etc etc.

Ive studied and studied and studied with what next to do. At the mo im only running 1bar. I currently dont have a afr gauge so dont want to go more than that.
Engine had a full rebuild last year with everything new oem toyota parts. I could have gone forged but i didnt want to.

Dont get mixed up with water temps (you say you have a uprated front rad) and inlet temps. High inlet temps will also make your engine go bang so you want something to keep that charge air cool too.
MR2DI4 swears blind the standard interwarmer and an uprated fan are fine....i beg to differ. Everyone has their own opinions. I went for a st205 chargecooler as it cools the inlet temps fine and is also monitored with a temp gauge with the chargecooler pump monitored too.

So in short, my opinion for your car with the ct20b would be to check the fuel (afr gauge would suffice for this and is handy to have anyway), keep an eye on the inlet temps or at least make sure the charge temp is ok , and then get a decent boost gauge (not the standard toyota one) and just up the boost a little at a time - and dont run the engine on the edge.

If the car has no history then your not gonna know if the head gasket is the rev 3 one so just keep an eye on it. Just make sure it doesnt get too hot and overheat too much as the cylinder walls can and do crack.

Ive ummed and aahed about the rev3 ecu management conversion which would give you bigger injections and get rid of the afm which im guessing is a bit of a restriction. This is an option but unless something comes up cheap enough, im not too bothered bout going that way and just enjoying the car as it is.
Brilliant! Thanks for the in-depth info.

The previous owner of my car did a LOT of upgrades including an uprated inter cooler and a proper boost gauge. So once I grab an AFR gauge i'll do as you say and keep an eye on everything. Turn the boost up a little.

But i'll keep an eye on that head gasket and replace it if I notice any signs its gonna blow. The car has done almost 160,000km so i'm not putting a whole lot of trust in that head gasket.

I have a pile of history for this car and everything has always been maintained very well.

Thanks again, just what I needed to know.

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Re: Boost controller for more power?

Post by MR2DI4 » 14/02/19 19:47

Nothing wrong with the stock Rev 2 head gasket, mine is almost 30 years old now and no problem. This is where I said your Cooling system must be basically spotless and has never been run without anti-corrosion for ALL of its life. The head gasket goes the second your coolant system fails, any head gasket will go the second your coolant system fails.

Basically 250Hp is nothing, this engine is good for 300Hp stock. The later model of MR2 came out with the SAME stock intercooler, you don't need to upgrade it its a waste of money. I did the intake temperature testing and a bigger fan on mine that cuts in at over 5psi of boost kills the temperature spikes. If you want to have an effect thats very close just pull the hood temp sensor for the stock fan, the result is still a significant temperature drop under full boost. I actually think this is one thing that Toyota overlooked in the design. It would have been very easy for them to kick in the stock fan over 5psi and build in an off timer to keep it running for up to 30 seconds after boost like I did. This really highlights the poor airflow through the side vent, the SPAL on mine is moving as much air as the engine is using at the redline.

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Re: Boost controller for more power?

Post by Sonac » 15/02/19 1:01

MR2DI4 wrote:
14/02/19 19:47
Nothing wrong with the stock Rev 2 head gasket, mine is almost 30 years old now and no problem. This is where I said your Cooling system must be basically spotless and has never been run without anti-corrosion for ALL of its life. The head gasket goes the second your coolant system fails, any head gasket will go the second your coolant system fails.

Basically 250Hp is nothing, this engine is good for 300Hp stock. The later model of MR2 came out with the SAME stock intercooler, you don't need to upgrade it its a waste of money. I did the intake temperature testing and a bigger fan on mine that cuts in at over 5psi of boost kills the temperature spikes. If you want to have an effect thats very close just pull the hood temp sensor for the stock fan, the result is still a significant temperature drop under full boost. I actually think this is one thing that Toyota overlooked in the design. It would have been very easy for them to kick in the stock fan over 5psi and build in an off timer to keep it running for up to 30 seconds after boost like I did. This really highlights the poor airflow through the side vent, the SPAL on mine is moving as much air as the engine is using at the redline.
How much boost makes 300hp? I seem to remember my father's old MR2 running 18psi for 300 but i'm not sure. I know the rev 2 runs 12psi stock. I'm probably gonna shoot for 14-15 to begin with and maybe 16psi if i'm feeling lucky.

Also I imagine the coolant system has been taken care of as well as the car it's self. But i'll check for coolant sludge once I get it and flush the system though if needed.

I like your idea of a fan for the intercooler though, I might look into something eventually. I really enjoy working on my cars so little projects like that are what I live for really.

Thanks

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