high boost

[Greenmr21990]

I am installing a boost control to crank it up to 15psi for the track. I have a boost cut controller so I can run over 12psi. I have heard that the stock ECU floods the cylinders with fuel as a safety mechanism over 12psi causing the car to run too rich. I have heard you can either advance the timing a couple of degrees or adjust the fuel pressure regulator to lean out the AFR a bit. Any suggestions on which is better? also, how would I go about adjusting either the timing or regulator? where is it in the engine compartment? and how do I adjust it? (I have a japanese 1990 right drive mr2)

thanks

[JekylandHyde]

You will not need to adjust anything to run 15 psi of boost.
Yes, the car will run a bit richer which keeps your engine safe.

Saying that above 12 psi the ECU "floods the cylinders with fuel" is really not accurate.

As long as your engine is healthy, you are using high octane fuel and your ignition components are fresh, you should have no problems running 15 psi.

[Greenmr21990]

thank you for the response. I am going to go ahead and set up the boost control. by the way ... it appears by the quote on your profile that you run quarter miles. do you ever run Nitrous ... can the mr2 engine take the abuse? A friend of mine said that he blew his mr2 1991 turbo engine running 18 psi of boost and only a 25 shot of nitrous. Is there a preferred mix of boost and nitrous. I would like to launch the car at around 6 psi of boost and then have it cranked to 15 psi for second gear and then maybe hit the nitrous button ... does the stock set up support such a strategy?

Thanks,

[JekylandHyde]

I have yet to see a reason to even think about nitrous.

I pushed an original stock engine with over 200,000 miles to a best 1/4-mile of 11.1 @ 125 mph. That was launching at 24 psi of boost and running 26 psi down the track.

The stock engine, if properly tuned can handle a lot.
If you do not control detonation, you can blow it up rather easily.

The current 1/4-mile stats in my signature are from the built engine that I got from Chico Race Works. I don't just do drag racing though. I do a lot of autocrossing and hillclimb racing. Check out my site if you have the time ... lots of information on there.

[Greenmr21990]

Okay so Nitrous does not sound like a good idea for the MR2. So, take for example, my car has 81,000 kms on it and is in pretty decent shape. How high could I take the boost on a mostly stock setup MR2 1991? I have a performance exhaust (excellent exhaust flow), and a Blitz cone air intake as the only mods so far. I would be using racing fuel mixed with premium to run approx. 110-115 octane level. I would like to take it to the limit but preferably not blow the engine. also, are there any relatively inexpensive upgrades to take the boost up even further? I assume that you had quite a few upgrades attached to your stock engine when you took it to mid 20s boost?

One other issue ... on the tires ... I have stock aluminum wheels that came standard on the 1990 Japanese Mr2 I believe. Any ideas on how wide I could go on these babies. I would like to try for 225s or 235s if possible.

One last thing ... When I bought my car it had a TRD stick on the side of it and several TRD upgrades .. shifter .. sway bars .. .stabilizers ... was there a japanese trd edition of the Mr2 released .. if so, were there certain upgrades that came with it? Or do you think these were just aftermarket editions by the previous owner.

Thanks again for your help.

[JekylandHyde]

The TRD stuff came aftermarket.

If you have the stock turbocharger, I would not go over 15 psi of boost - ever.

If your stock wheels are 7" wide, you can doa 225 and probably a 235.