J
JerzeySlowpra
Guest
im with mrsupra on this one, i also think 20 is way on on pump, on stock fuel system stock compression, stock everything
Well, I found the limit for a stock head gasket.
- Thread starter GrimJack
- Start date
You could be right - we'll see what the dyno says when I put it back together.JerzeySlowpra said:
Start a "donate a dollar for GrimJack to dyno thread". I think you were pushing over 400rwhp at that level since I hit 293@12psi on the stock CT26 and 345@13.5psi on the SP61GT.
I would pay a dollar to see your A/F ratios on the dyno at WOT.
Not saying you need charity or anything, but for a guy that seems to be well above the curve, running that much boost on 94 and stock fuel doesn't make sense.
I'm not sure I buy the 100ftlbs reason for failure advanced by some folks but as you stated you were looking to push the limits, and you did, but it would be nice to know exactly what produced the failure
I would pay a dollar to see your A/F ratios on the dyno at WOT.
Not saying you need charity or anything, but for a guy that seems to be well above the curve, running that much boost on 94 and stock fuel doesn't make sense.
I'm not sure I buy the 100ftlbs reason for failure advanced by some folks but as you stated you were looking to push the limits, and you did, but it would be nice to know exactly what produced the failure
Something that I should point out for all the newbies that might read this thread sooner or later - I absolutely would not suggest running this much boost without some serious tuning - UNLESS you happen to have a spare longblock sitting aroun waiting to go in, like I do. I've been trying to kill this engine for well over a year now, basically just to see exactly how tough the 7M series really is.
GrimJack said:
hahaha i was waiting for someone to post, "i turned up the boost like grim and damnit"
lol
:biglaugh:
sorry i only skimmed most the thread so sorry if this was covered but....
did the HG blow simply from "too much boost" or were you detonating?
im planning on pushing the stock HG to its limits and from what other veterans have said i gather that the stock HG will hold whatever you throw at it (given proper torqued head studs) as long as you tune it. if you keep detonation in check it should hold.
did the HG blow simply from "too much boost" or were you detonating?
im planning on pushing the stock HG to its limits and from what other veterans have said i gather that the stock HG will hold whatever you throw at it (given proper torqued head studs) as long as you tune it. if you keep detonation in check it should hold.
Lagged, I'm pretty certain I was hitting some detonation. Could have just hit the limit for power on a stock head gasket too, I suppose - when I get it back together I'll throw it on a dyno and see about where it was power wise. But I think the power would have to be well over 400 rwhp to deform a Toyota gasket that badly.
I should post some pics of the gasket.
I should post some pics of the gasket.
It was more a detonation problem than a boost problem at that boost level on pump gas. You can't tell if a piston is nuked or not till you pull it out of the motor. It can look flawless ontop while the ringlands are all cracked.
im no expert but i would attribute the HG failure to detonation then, and not to excess boost pressure.
J
JerzeySlowpra
Guest
i willing to bet, on better gas, more fuel/air and whatever tuning to stop detonation the stocker would take it at 80-100fts lbs, im only saying this cause i met someone recently with a t70 series turbo running a stock block, stock head, stock gasket, arp's 550's, adj fpr, afc, vpc, exaust blah blah, going 11.8 at the track and i was later surprised to find out when i talked to them everything is completely stock specs except the arp's... and running 20 lbs of boost on whatever octane race gas
You actually get that much more power by just turning up your boost on these cars? I figured taking a stock supra and turning the boost up to 12psi or so you'd get around 250 hp.. what hp does 10psi typically give you? and jesus christ grim... you must have been wanting to destroy that engine by running it at that high of psi.
Adjuster
Supramania Contributor
Sirkus, the accepted "scale" for the CT is about 11rwhp per extra psi of boost pressure.
IE: going from 5psi to 10psi adds about 55rwhp to the car. The tourqe gains are more IIRC, but I don't have a number for that. Perhaps 13 to 15lbs ft per psi? Again, no hard data.)
With my bolt on T4 60-1, it's more like 14rwhp per psi..
And you can run 20psi on pump gas. It's not a good idea unless you have good pump gas, but just don't spike to say 28lbs... it melts pistons
All this talk about annealing the head has me worried. I baked my head, and many other parts at 400F for a few hours to cure the coatings. It was in an oven used to straighten heads. (Flat surface they clamp warped heads to, then heat them to take out the warp.)
So far, no problems with this head. Hope this continues, if not, time for a new/used un-baked head I suppose.
IE: going from 5psi to 10psi adds about 55rwhp to the car. The tourqe gains are more IIRC, but I don't have a number for that. Perhaps 13 to 15lbs ft per psi? Again, no hard data.)
With my bolt on T4 60-1, it's more like 14rwhp per psi..
And you can run 20psi on pump gas. It's not a good idea unless you have good pump gas, but just don't spike to say 28lbs... it melts pistons
All this talk about annealing the head has me worried. I baked my head, and many other parts at 400F for a few hours to cure the coatings. It was in an oven used to straighten heads. (Flat surface they clamp warped heads to, then heat them to take out the warp.)
So far, no problems with this head. Hope this continues, if not, time for a new/used un-baked head I suppose.
Another thing to note is that virtually everyone here has 94 octane at the pump. Plus, our gas is rated at a minimum - so buying 94 might actually net you 97, 99, or 100.
For anyone that was following my thread, I posted some pics in a shiny new carnage thread. Have a peek!
http://www.supramania.com/forums/showthread.php?t=5551
http://www.supramania.com/forums/showthread.php?t=5551
dont forget that there is a hose full of unknown octane fuel left at the pump from the previous patron. so when you fill up on your Sunoco Ultra94 (thanks mom!), you could very likely be getting 87 octane in that hose contaminating your fuel.
anyways, good work with that. i suspect race gas would support more than 20psi of boost
if you know how much HP you were pushing, its safe to say that the cylinder pressures associated with that power level are what could have caused your failure... assuming there wasnt massive detonation. however, if tehre was alot of knock/detonaton, then we can blame the failure on that, and not an indication of TRUE hp levels killing the gasket.... but if you were running race gas and good timing and minimal knock, the hp experienced at that level and the associated cylinder pressures are the real gasket killa!
anyways, good work with that. i suspect race gas would support more than 20psi of boost
if you know how much HP you were pushing, its safe to say that the cylinder pressures associated with that power level are what could have caused your failure... assuming there wasnt massive detonation. however, if tehre was alot of knock/detonaton, then we can blame the failure on that, and not an indication of TRUE hp levels killing the gasket.... but if you were running race gas and good timing and minimal knock, the hp experienced at that level and the associated cylinder pressures are the real gasket killa!
Here's how my 3-year old stock HG looked when I pulled it apart last month:
91 octane is the highest I can get on a regular basis here in California. Combine that with 18 psi of boost and hot temps and...well...see above. :nono:
91 octane is the highest I can get on a regular basis here in California. Combine that with 18 psi of boost and hot temps and...well...see above. :nono:
J
JerzeySlowpra
Guest
JerzeySlowpra said:
83 ft lbs. There was no machine work done to the block or head, so it's likely the head was warped from day 1.
I never planned on building this car when I did the first HG. This time around everything has been machined and I am running a Cometic MHG.