Outer Limits 4x4 Board

Hey All

What boost do the 12HT's run standard? is it 7psi? has anybody tweaked theres up? what would be the max boost the engine could take (before it starts buggerin things up?) and how hard is it to do? what sort of performance increase can be gained???

Reason i ask is because would love to have just that little bit more power there if need be, like when overtaking etc etc. and i know if i wanted speed i should have bought a sports car, so no smart comments allowed

Cheers Troy

there's a lot of factors to consider when determining a "safe" boost level. The condition of the motor, the condition, type, and efficiency of the turbocharger, intercooler or no (and if intercooler, how efficient is it), injector condition, etc etc. The overriding criterion is your exhaust temperature, so if you don't have an EGT gauge fitted up, go get one and fit it before doing anything else.

ok, got your EGT gauge? now read on.

with the factory turbocharger, and without changing anything but boost and fuel, you could probably go to around 10psi without breaking anything. Set your boost (got no boost controller? shoulda picked one up while you were out getting that EGT gauge. and a boost guage too, eh?) - ok now your boost is set, now creep up your fuel until your EGT peaks at around 600C, post turbo, on a long, hard, third gear uphill run with around 2500 rpm.

not enough power? first thing you need to do if you haven't already is open up the exhaust. a straight through, mandrel bent, 2.5" system (no mufflers, just a nice round pipe) will yield good results. you will probably find that opening out the exhaust liberates an impressive amount of high rpm torque.

still not enough? intercooling is the next stage. shoot a PM to carts, he is probably parting out his turbo 60 with HUGE intercooler. you could probably push the boost to around 12 - 13psi but that would be on the absolute limit for the stock turbo. probably too far.

still need more? a bigger turbo is what you need. start talking to professionals and handing over big monkey, or just grab a 300ZX ball bearing/ceramic turbine unit, (under $500 from importers) should be good for up to 20psi on a 12H-T, which is about where I'd start to panic about the integrity of the internals of the motor.

at every stage, your aim is to increase power, and decrease or keep steady the coolant and exhaust temps. mister EGT gauge is your best friend.

ooh look, you've spent $4000!

cheers

DD

Amen, Cheers heaps for that, let the work begin Your A Champ!!!

Have a great Easter

dumbdunce wrote:there's a lot of factors to consider when determining a "safe" boost level. The condition of the motor, the condition, type, and efficiency of the turbocharger, intercooler or no (and if intercooler, how efficient is it), injector condition, etc etc. The overriding criterion is your exhaust temperature, so if you don't have an EGT gauge fitted up, go get one and fit it before doing anything else.

ok, got your EGT gauge? now read on.

with the factory turbocharger, and without changing anything but boost and fuel, you could probably go to around 10psi without breaking anything. Set your boost (got no boost controller? shoulda picked one up while you were out getting that EGT gauge. and a boost guage too, eh?) - ok now your boost is set, now creep up your fuel until your EGT peaks at around 600C, post turbo, on a long, hard, third gear uphill run with around 2500 rpm.

not enough power? first thing you need to do if you haven't already is open up the exhaust. a straight through, mandrel bent, 2.5" system (no mufflers, just a nice round pipe) will yield good results. you will probably find that opening out the exhaust liberates an impressive amount of high rpm torque.

still not enough? intercooling is the next stage. shoot a PM to carts, he is probably parting out his turbo 60 with HUGE intercooler. you could probably push the boost to around 12 - 13psi but that would be on the absolute limit for the stock turbo. probably too far.

still need more? a bigger turbo is what you need. start talking to professionals and handing over big monkey, or just grab a 300ZX ball bearing/ceramic turbine unit, (under $500 from importers) should be good for up to 20psi on a 12H-T, which is about where I'd start to panic about the integrity of the internals of the motor.

at every stage, your aim is to increase power, and decrease or keep steady the coolant and exhaust temps. mister EGT gauge is your best friend.

ooh look, you've spent $4000!

cheers

DD

Superb response .. should be archived for future reference

i 2nd that, that was a top resonce DD cheers again

Bump,

DD do you know of or have you heard about 12ht engine being basiclly the same as a certain yamar marine engine?? Using the same block, but different turbo and different fuel pump spec???

If so would you have engine number for this??

Reason I ask is these bits would be awesome for a comp truck build up, because of the up graded components.

Regards Daniels

DanielS wrote:Bump,

DD do you know of or have you heard about 12ht engine being basiclly the same as a certain yamar marine engine?? Using the same block, but different turbo and different fuel pump spec???

If so would you have engine number for this??

Reason I ask is these bits would be awesome for a comp truck build up, because of the up graded components.

Regards Daniels

yes Yanmar does HSV-style power ups on toyota motors for marine applications. I think it still gets called a 12H-T though. (could be wrong). you can still get Yanmar 1HD-FT marine engines that make buckets of power, too.

I don't think there's a lot of benefit on chasing up specialist marine parts for street/offroad applications - a lot of the power availability of marine engines has to do with their constant running at a steady rpm with a near constant load not to mention the unlimited coolong capacity of the ocean.

you can trick up a 12H-T for not a lot of cash if you're willing to do a lot of the work/r&d yourself. A suitable intercooler of ebay is only $250ish, a bigger turbo you can get second hand from importers for under $500. the rest is plumbing, which might set you back $500 or so at an exhaust shop.

cheers

DD

i know this probly isn't wise and i've stated it befor but the 12ht can take up to 24lbs of boost for a while i've seen one that ran it for a year and still going strong but i don't know the details.

Thanks DD,

yeah I wasnt sure of what was done to the engine in the way of up grading pistons, rods etc.. It sounds to me that they may just use a larger spec turbo and different fuel delivery (water cooled turbo housing etc) just a thought anyway...

Im aware of the constant load factors and cooling avalible to marine engines and get to see it with our engines here at CAT , very interesting stuff indeed.

Thanks again.

Daniels