7mgte Dynoed Today

[Grandavi]

you dont want to go above 15 psi with OEM pistons... unless you can afford the rebuild later...

All depends on what you want to get "safely". If your not concerned.. up it... : )

 

[jonahs_supra]

I would suggest another shop

 

[Grandavi]

You guys are telling him to up his boost... I think that's a mistake, so correct me if I'm wrong..,

On a stock shortblock with an oem headgasket, your advising above 15 psi. While the turbo would take it, I'd be worried about the pistons and head gasket. My research dictates 15 psi+ to be beyond Oem pistons safe range. 14 should be safe, but anything higher is risking the engine if he has an oem (and older) shortblock.

Am I wrong?

Also an unprepared head isn't the smartest on a 7m, regardless of the Arp's.
to me, this is a "half build" that I wouldn't stress too much.

 

[SC61 MK3]

In short, yes you are wrong

Questions should be answered with real world experience not "research"

 

[Dan_Gyoba]

IIRC, Reg Reimer (Who is super conservative with his builds/power) ran his '82 GTE with a stock shortblock, stock head gasket, stock head bolts (Torqued to 72 ft-lbs) and an HKS turbo with intercooler up to 21 lbs boost when testing the limits of the Lexus/550 upgrade. It's a given that all of these components were good as new (Or better) when he did so, but I'm positive that he'd never have done so if those components couldn't take it. It's also safe to say that those components weren't tuned to make the best possible power, but instead were in the safe "pig rich" configuration, but I still remember that being near 475 RWHP.

That said, I think that it would depend on how confident you are in the components and the build. The OEM head gasket will do fine if you keep it away from detonation. Similarly, the OEM pistons will also be fine. Get "incipient knock" however, and it's time for a teardown. Forged pistons and a MHG will only buy you a little time with the same conditions. Keep the AFRs in the safe zone, and you'll be as good as your build.

 

[Insidious Surmiser]

As far as I'm aware... a good tune on a stock 7m shortblock will hold 700hp.... how long is the question. There's honestly a lot of variables at play, and on an old engine it's hard to account for all of them.... people generally consider 500hp to be a "safe" number (and of course 400 even safer), just for the sake of being conservative I suppose... but still I've heard of OEM gaskets blowing w/ mild upgrade (and yes torqued properly) So it would be better to be safe than sorry.

 

[Grandavi]

In short, yes you are wrong

Questions should be answered with real world experience not "research"

there is no such thing as "real world experience" that covers everything. My research is the same as the OP... ask those who have done it.. see what they say. Add that to the knowledge base. My engine just got upgraded and I was trying to be super safe on the build.. and all the people I talked to (WITH the real world experience) warned me about going over 15 psi on OEM pistons. They didn't explain in detail why, but they said it was possible, but not smart. Its why I went the extra $$ with forged pistons.
There are other little niggly things about the build that can affect it as well, but there are "basics".

Your answer "yes you are wrong" explains nothing. Anybody can say I'm wrong.. I just like people like Dan, that add an explanation. Especially if it makes sense.

My strongest point would be that telling the OP to go higher may not be smart without knowing what his bottom end is. Funny how many people I have met with Supras that dont run...

 

[SC61 MK3]

The fact that you keep referring to the engines limit in PSI and not HP/TQ clearly shows your lack of knowledge.

It's time to stop posting

 

[Dan_Gyoba]

Great. Why not share some of that knowledge? He knows that he has a lack of knowledge, and he's not an idiot.

Advise being given to the OP is to increase boost, and Grandavi is asking if it's a good idea to that level. If we assume that the shortblock is in good health and will be well maintained, it ought to be. The OP is running a standalone, which is fully able to be tuned to make it safe, along with a turbo of perfectly adequate capacity and as such it all depends on the tune.

 

[Grandavi]

Actually.. ignore everything I said in this thread.

I am going about this wrong...

 

[Insidious Surmiser]

grandavi... I believe the reason you may have gotten the advice you did is because on stock electronics a ct pretty much stops making power @ 15 psi. I understand w/ a standalone you can pull a bit more power, (also meth inj. would net more power) but the turbo will be pumping some unpleasantly hot air @ this point. I can't say much on the .57 trim as I have no flow chart to reference.

 

[Grandavi]

Yeah, I missed the AEM stand alone on the first post.
Now I feel shame...

 

[jonahs_supra]

I can tell you from my experience on my motor
91 gte 88k miles. Stock turbo at 23psi, maft pro, walbro 255 and raised fuel pressure, 3in turbo back, fmic
With atleast 10k miles seeing 23psi my stock pistons look perfectly fine
Again this is on stock ct not a 6262 that will flow more

Even at 15psi on a 6262 his hp is to low.

 

[Insidious Surmiser]

yea that last bit was exactly what ran through my head as soon as I saw the specs/figures

jonah... you are running an upgraded IC, right?

 

[Nick M]

Thank you I did not do the metal head gasket because I did not deck the block. I was told you had to deck the block in order to use a metal head gasket

The block and head need to be flat whether you are installing a metal head gasket, or composite.

 

[Grandavi]

The block and head need to be flat whether you are installing a metal head gasket, or composite.

of all the items on my build list.. this was the one that featured most dominantly. After 3 years of reading about HG failure... I opted for a properly decked block and ARP studs. Unless there are other erroneous issues I missed, I should never have to retorque or worry about the head.

 

[jonahs_supra]

yea that last bit was exactly what ran through my head as soon as I saw the specs/figures

jonah... you are running an upgraded IC, right?

That is correct. Spearco. Iat are not very high. Switching to e85 over the winter

 

[Insidious Surmiser]

cool deal. I know those old stock units like to get heat-soaked (as well as the whole damn mkiii, LOL)

 

[ClutchRR]

You guys are telling him to up his boost... I think that's a mistake, so correct me if I'm wrong..,

On a stock shortblock with an oem headgasket, your advising above 15 psi. While the turbo would take it, I'd be worried about the pistons and head gasket. My research dictates 15 psi+ to be beyond Oem pistons safe range. 14 should be safe, but anything higher is risking the engine if he has an oem (and older) shortblock.

U are right my tuner tuned it extremely safe. Due to my stock block. Also my head was decked. However I did not deck the block. But the block was even.
Am I wrong?

Also an unprepared head isn't the smartest on a 7m, regardless of the Arp's.
to me, this is a "half build" that I wouldn't stress too much.

 

[ClutchRR]

My simple solution to my fix is im going to build a spare 7mgte fully and swap out engines. So its less down time. That build should be fun. Im very happy with my progress on my MK3. I bought it last april with a blown head gasket and in limp mode. So this is the first time I actually have my car running right with no issues.