how much boost can a stock 7mgte hold??

[boosted88mkIII]

just wondering if anyone knew how much boost a bone stock 7mgte can hold and the best way to get it?? I've seen shimmed waste gate but that's a little sketchy to me... any tips

[btwilson86]

Bone stock you'll see about 6 PSI of boost. To get more than that, you can upgrade your exhaust, install a boost controller, upgrade the turbo, shim the wastegate (I personally don't recommend this method).... Basically, there are several different methods to increase boost pressure. I believe the easiest way to gain more boost would be to buy or construct a manual boost controller. This method also allows you to adjust the amount of extra boost, depending on your needs.

With all that said, I wouldn't recommend running much extra boost on a tired 24 year old engine; extra boost equals higher combustion chamber pressure and stress, which typically exposes hidden problems (such as a weak head gasket). Make sure your engine is healthy and in good running condition before trying to force more power from it.

[pandrade]

iv heard about shimmiying the wasegate and read about it on the faq's but has anyone done it and would like to give me there opinion on it

a healthy 7mgte can handle 12psi on a factory turbo right? i think i read that if you push much more out of it your looking for trouble

[Green7mgte]

Originally Posted by pandrade

iv heard about shimmiying the wasegate and read about it on the faq's but has anyone done it and would like to give me there opinion on it
a healthy 7mgte can handle 12psi on a factory turbo right? i think i read that if you push much more out of it your looking for trouble

the general opinion on the shimming is retarded.. when there are safer ways.. for instance.. 12 bucks gets you a manual boost controller..

as for safe boost.. anything above 12 and your looking at forged internals..
granted everything is in top shape..

your sig says 135k miles on a stock platform.. I wouldn't shoot for 12 less you restore your engine first. 20 years is 20 years.. no matter how much you babied your car.

[cre]

Agreed. Shimming the waste gate isn't just retarded but it's also hazardous. For every millimeter you shim out the actuator you remove a similar degree of motion from the wastegate's toatal allowable travel distance steadily increasing the risk of boost creep. On the upside, unless you're running a poorly setup FCD, you'll just hit boost cut but that's still no fun and if you're on it hard enough that may not kick in soon enough.

I need to go through the FAQ and remove the references on shimming or annote them all.... Oh goody, more work.

If you want to build a cheap boost controller on your own google "grainger boost controller".

Addendum:
I can't find any FAQ on shimming the wastegate. Anyone care to provide me a link with where they are finding this? I'm sure it's in a thousand and one threads throughout the forum but I'm not going to edit all of those. I just don't want it in the FAQ sections.

[pandrade]

this is the link on the FAQ'S that tells about shimmying the waste gate

http://www.toyota-supra.info/forums/...-websites.html

then click on this one www.SUPRAS.com - Member's Section

i wouldent take it off the FAQ's alot of other good thinks on that link i would warn about the bad effects of shimmying the waste gate , or maby make a FAQ page of most common mk3 and 7mgte myth's which would cover this

and on a side note does any one know of a good manual boost controller they would recomend

[btwilson86]

Originally Posted by pandrade

iv heard about shimmiying the wasegate and read about it on the faq's but has anyone done it and would like to give me there opinion on it

a healthy 7mgte can handle 12psi on a factory turbo right? i think i read that if you push much more out of it your looking for trouble

When I got my first 87 turbo, it had a shimmed wastegate. It worked just fine, but it causes extra stress on the wastegate actuator diaphragm and I'm sure other parts. Unneeded stress when, as Green mentioned above, there are easier and safer methods to achieve the extra boost.

[qbizzle]

The shimming is not a bad idea really I get an extra 2psi off of it but I'm still going with a manual boost controller there like 15 bucks

[supraheelfan]

This is amazing. All these responses to shimming the waste gate for more boost and no one responds to an actual problem that plagues the 7mgte; like blow by on old engines like ours the 7mgte and you know you cannot find a 7m that is newer than 23yrs old. So since most ppl on here have 24 year old engines and blow by is a serious problem for turbo engines when boosting, if not maintained meticulously, it should get some attention. B/C most ppl having been boosting more than 10psi for a while and b/c 50% of ppl don't care how something works until it stops working, then a good talk needs to be had to inform the uninformed about owning classic technology on cars like ours (even though the 7mgte's tech is standard today it wasn't back then and wasn't made as efficiently as today's cars). Most ppl don't know how old engines deteriorate, and the 7mgte is turbo and since 90% of ppl know it can take high boost on the bottom end and shimming your waste gate should be temporary at best; then why no answers on proper PCV maintenance? Especially since there are a ton of shimming threads out there and only now starting to see more PCV ventilation threads as years go by. It just would be nice to start talking about the problems we will soon be dealing with instead of talking about something that has been covered over million times and can be found with the search button. But try searching for how to maintain your old engine so it stays in top shape and you will be hard pressed to find many.