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Discussion Starter #1 (Edited)
Hi all,

Currently building a track car that needs to be reliable for 15/20 min stints at high speed circuits, lots of sustained boost. Car is rev3 tubby and at the moment completely stock except bc coil overs, 3inch decat downpipe/exhaust and slotted discs.

Would an uprated greddy style intercooler be ok for stock boost?

I’m trying to decide between this and a st205 charge cooler and boost controller at 1.2bar

Which do you think is a more reliable setup out of these?
 

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A SMIC is always a good idea, stock or semi mod’d... the oem cores really suck... think of it as cheap insurance...
As for higher hp setups, a rmic setup is best... I made a vertical mount hanging down and it was really effective... I had an HKS T51-R turbo and it was 500hp and the hot side was always noticeably cooler than it probably should have been if it were in engine bar... the SMIC are cheap...
 

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The primary advantage of a charge cooler is that you have more thermal mass before the engine heat soaks, the water is harder to heat up. Once you heat soak though a water to air charge cooler is actually going to be less efficient than an air to air intercooler because you have a longer path from the intake air to the cooling radiator. The heat has to be absorbed into the charge cooler, then transferred to the water, then pumped to the radiator, then the heat can be dissipated from that radiator.

So a water to air charge cooler makes a lot of sense in a street car because the time spent in boost is not much, the water can absorb transient spikes and the steady state is out of boost so there's less need to prioritize steady state cooling. You can also do fun tricks like peltier coolers or filling the coolant with ice cubes for drag applications to get sub-ambient IATs. It also reduces the intake air volume to be pressurized in transient applications, you don't need to route the intake air to a large air to air core with good airflow, then back to the engine.

As for what the best solution is? For pure performance it's likely the charge cooler. For MR2s the side mount intercooler does not get a lot of airflow, whatever thermal impedances exist in the W2A system are not as important as proper airflow through the core. You would have to put the radiator for the system somewhere useful like the front of the car, otherwise there's no real benefit.

For reliability? I think the upgraded SMIC has the least things to go wrong. But the airflow is going to be worse, no doubt about it.

If you want to keep it simple I would just upgrade the SMIC and leave it there. If you aren't pushing a lot of power the 9" fan will move enough air, also make sure there's proper ducting to make the fan/natural airflow go through the core instead of around it. Avoid pushing too much boost, if you push the turbo past the efficient regime you will be making a lot of heat that the intercooler has to reject. If you want more power than a turbo is really designed to deliver replace the turbo with something better suited to your power goals.
 

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Discussion Starter #4
Thanks guys. I think I will end up just going for the charge cooler. But one more question, how strong are these engines really? Would people expect me to have any problems at 1.2bar for extended track stints on standard internals? I just really don’t want it to blow:)
 

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1.2 Bar generally will break the ct20b's ceramic turbine, while I'd say it's safe on a street car a track car should really have the boost turned down.
 

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The engine themselves are fine motors and can handle a lot of power, it’s the Mickey Mouse computer and electronics that are the problem.. I stuck a haltec on a stock 91T and made 290hp with larger injectors and SMIC... I’ve moved on to a 2GR... I’m not a turbo 4 fan...
 

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Discussion Starter #7
Hmm, I guess I’m just put off by side mounts when people say they will heat soak even at stock boost and high IATs are number one cause for bye bye engine.

I guess a charge cooler or boot mount is just a mandatory thing to do for mr2 tubby track cars, which is a shame as don’t like the extra complexity/cost
 

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Those SMIC work fine if your 350hp and under.... you could just take a SMIC core and run it under the trunk... try it!! It’s only tubing... if you ever wanna see what those little things do, run a tube from turbo to core... the power is terrible
 

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While I agree with Joshua96’s comments for the most part there is a few corrections.
The main advantage with A2W is that the radiator can be placed up front where it gets maximum air flow. The second correction is the lower restriction in aircharge path between compressor and TB.

Regardless of what IC you choose others have highlighted potential issues with running 1.2 bar. Potential turbo failure is possible and will depend on the exhaust & engine cooling design. This can be another advantage for A2W as with SMIC removed the side vent can be used to direct air to firewall side of engine.

The other consideration for running high boost is fuel quality. Detonation control is paramount in reducing engine failure modes. Having high internal temperatures increases the likelihood of detonation which is why high octane fuel is required. Although adding complexity to the system, my preference is to use a water injection system to assist with controlling detonation. It also has the advantage of cooling aircharge much like an IC and supplying center two cylinders with cool air. This is important as most failures occurs in these cylinders due to the engine geometry.

Regarless of what you choose to do it is important to install modifications professionally and be prepared for failures. Need to have some sort of reliable monitoring equipment so you understand what is going on with engine during the hot laps. Can be as simple as warning lamps or temp gauges. Shutting down before engine self destructs will save you every time. The key is recognising an issue before it becomes problem.
 

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I did forget to mention that A2W reduces turbo lag, that's a good point. It doesn't work miracles but it helps to not pressurize as much volume.

Simplest solution is going to be SMIC upgraded and keep the power down, if you constrain your turbo boost target the IC has less work to do. The other option is a charge cooler and running a new set of hoses all the way down the car to the front. You'll get more headroom but it's going to be a bigger job.
 

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Here's my biggest question, what are you trying to do here? Does .2 bar really mean a whole lot at these track days? What are you really going to get out of it? Are you the next Senna? Lower your boost and enjoy the car, it's not like you're going to be competitive against anything here, these are 30 year old cars at this point just have fun and don't chance breaking a piston.

You could spend 2 grand trying to chase 10whp for a track day, or you could focus on nice suspension and tires that would really make a difference.
 

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Agree^ .... even most important, look for these answers on this forum yourself... that’s why it’s all saved...this back and forth BS will never get you an answer... read the forums
 

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I used to do track days here in SoCal. Race gas is great stuff, but I would see lots of spark retard on hot track days. (I have a J&S which is a vintage knock detector that can retard the spark.) Then came a Greddy sidemount with a Spal fan and a custom shroud. That was great for the street, but didn't totally solve the problem at the track. Finally, I added water injection. Water injection is a real pita, but it does the trick.

PS: This is at stock boost plus maybe 2 psi due to reduced IC pressure drop.
 
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