Higher than stock 4psi boost on the 1MZ-FE?

[JoeB]

Well, the age old question, "How much can I increase the boost"? A question that I think everyone asks that gets the supercharger. You just spent all that money on a supercharger and you can only run 4psi?!

A couple years ago someone posted that the theoretical max at sea level was 5.5psi. I started asking why not more, what is the limitation and was told it is too much pressure, I'd crack a piston, lose a ring landing or blow the head gasket but the indicator of problems would be knock. I very carefully raised the boost to 6psi, 7psi and lately 8psi pulleys. I think my problems started when I went from 6psi to 7psi. I ran a 14.05 on my first run at the track, did some mods including the 7psi pulley and ran over 15secs. Since then I've done a few more things including the 8psi pulley and have got the times down to 14.2. Unfortunately this weekend I found I'm doing that with at least 2 cylinders not running well. 120psi and dry in 1 and 110 and oily in another.

So it's off to a rebuild. Arrieta Motorsports has done 2 other Solaras building the bottom end and mine will be the third. As part of the build, since nobody makes high performance rods and pistons for our engine, it's off to Stoid Racing. These are the guys that built Brad Bedell's 1MZ-FE that went in his MR2 that won the Ultimate Street Car from SCC Magazine running 500whp. They custom machine a set of Toyota 22R rods to fit and a custom set of Arias forged pistons. All of the engine work will be done by Arrieta Motorsports. This is a family owned and run business that has generations of racers in the family. They are very conscientious and take great pride in their work. -JoeB

[lazyboyz69]

i'm pushin 6lbs and i think its fine with the fuel upgrade of course

[JoeB]

i'm pushin 6lbs and i think its fine with the fuel upgrade of course

It's possible it is fine but do you know for sure? Do a compression check on the front 3 cylinders. It is VERY easy and quick to do. The cylinders should be around 190psi. I think I was ok at 6psi too (guessing). Like I said, you couldn't tell by the way the car is running, very smooth and still runs 14.2 1/4 miles.

There aren't too many people with more fuel upgrades than I have. I have the Walbro 190lph pump, modified regulator to 59psi, 318cc injectors, Jim@ForeignAffairs filter and lines, the Split Second FTC to adjust fuel/timing and a PLX Devices WBO2 guage and Bosch sensor. I think I had the fuel pretty well covered. -JoeB

[SC V6]

yeah im still running the 4psi pulley, adn I have the wablro 190lph pump, supra injectors, jim's fuel upgrade, and the s-afc II... Im still worried.. I even have the low compression heads.. I think I may try to put the 6psi pulley on next year... but I dunno.. Id rather run 4psi all day, than strap the 6 on and blow a motor

[ChiTownSolara]

yeah im still running the 4psi pulley, adn I have the wablro 190lph pump, supra injectors, jim's fuel upgrade, and the s-afc II... Im still worried.. I even have the low compression heads.. I think I may try to put the 6psi pulley on next year... but I dunno.. Id rather run 4psi all day, than strap the 6 on and blow a motor

just use the 6psi pulley at the track with some race gas and use the 4 psi pulley for daily driving...

[Paladin06Greg]

Well Let me say this for the record. The pistons used when the motor is built by Toyota are nothing less then "CRAP". You can play with more then four pounds of boost if you like but "you will PAY" later.

I've got my three shot pistons at the house in my special room, just as a reminder..

O'yes, and the head gasket "paper trash"!!

[SC V6]

ive got 4 blow pistons at my house just chillin

[Vampire]

JoeB, very sorry to hear that. I think I can speak for others in that I appreciate your honesty and sharing of information. I know of at least 2 people who have boasted great numbers but never mentioned that they blew their knock sensors or had other problems. No doubt you had your fuel covered but like the rest of us we may have fosused too much on fuel delivery and knock. I wonder if all the dyno runs and track days had something to do with it. Anyway, my SC was dropping a little oil about a month ago and while I waited for the gasket sealer to dry I did a compression test and it was good. I have been running a URD 7psi pulley and I guess I have been very very lucky. On the bright side, I always intended to build up the motor and I guess you are just doing it a little earlier than you wanted. When that's done you should be able to throw what you want at it. Let us all know how it works out. Good Luck!

[JoeB]

Paul,

Thanks. The forum is all about sharing info. I am certainly no mechanic and I came here to learn. When I first started visiting this and a couple other Camry/Solara forums 2.5 years ago, I was trying to learn what I could do with my car to fix it up for both looks and performance. I really didn't have a clue and was relying on the experience of others. I asked many questions about why we couldn't run more boost. Unfortuanately since the car is so new, there was little experience in the community and no good answers. I was just told to watch for knock. I made sure I did everything I could to balance air/fuel delivery as you said and monitored knock, A/F with a WBO2 gauge and EGTs. I really appreciate all I've learned from you and many others here and try to do my part in sharing.

I think the problem is simple physics. It is just too much pressure. When you get knock, it is just exagerated. Until they tare my engine apart, I won't know the exact damage but I doubt I lost any pistons, I'm thinking the ring lands went. The car still runs great. No doubt the track days and dyno runs played a part. Like you, I always planned to build it some day. I guess this is just "some day". If I didn't come here and tell others about the experience, I would just be taking and not giving. Hopefully we will better identify the safe boost levels and different performance upgrades people can do at their price range.

I really think the safe limit with 93 octane pump gas is 6psi and probably 5.5psi for 91. What really scares me is guys that go to those levels that don't tune the a/f to handle it. The Solara has been out for 5 years now, we are still learning exactly what we can do with it. -JoeB

[Vampire]

Well put Joe. My feelings are the same. I can't believe I've been on some of these boards for years. I would like to say that you really helped the community out and things really didn't start going in the right direction till guys like you and Jim started doing things and posting progress reports.

[SC V6]

I would say after tearing my engine apart, that the piston lands are the weak point.. cause I didn't lose any pistons, just the lands...

[Paladin06Greg]

You are correct but, I see them as part of the next higher assembly, that being the piston.. Toyota firmly stands their ground that anything higher them 4.0 with stock internals is asking for trouble. I have parts to prove they are right..

I would say after tearing my engine apart, that the piston lands are the weak point.. cause I didn't lose any pistons, just the lands...

[SBCelicaGT]

Pictures! I want to see a busted piston!

[Fletch]

For those who have checked compression, did you do it with the engine cold or hot and did/have you noticed oil consumption?

[JoeB]

Fletch, I checked the compression with the engine cold. Is it better to check with the engine warm? Even if so, that wouldn't make up the difference between cylinders. I had 190 in #6 and 110 with oil on the plug in #2. -JoeB