My UZ's boost limit

[JustenGT8]

My UZ's boost limit - 700hp!!!!!

Well as some of you know i have been looking to add to the current boost i run (13psi).

I hit the dyno for some proper tuning but the initial road tests were a bit interesting.

I can hit 15+psi in a blink bit 15 seems to be the limit of decent running as at this level it develops an obvious miss.

It's not det so could ignition break down but as i was running a 1.1mm gap on 13psi no probs and have now closed down to 0.8mm i don't think so. I actually think the issue is the soft valve springs not holding the higher boost.

Hopefully the dyno will shed more light but if it is the valve springs then only way i'll get m ore hp is a leaner tune and more ignition advance....stay tuned i guess.

 

[boostedtundra]

This sounds dangerous---the first thing you should do is fit a fuel pressure gauge at the regulator as the fuel leaves the rail and put it in a place that you can see when running. Make sure that there is no pressure drop at max RPM/boost. It is possible that you are running out of fuel.

 

[JustenGT8]

Nope fuel is fine......have pressure gauge but more importantly a/f ratio is spot on.

 

[cribbj]

Justin, maybe it's still in the ignition, but just not the plug gap?

Granted, the symptoms should have changed a bit when you gapped down. How are your wires, etc.?

 

[Zuffen]

At 15psi you've more than doubled the operating pressures in the cylinder.

I'd suspect the spark isn't strong enough to operate at those pressures.

Perhaps it time for an igniter upgrade?

 

[JustenGT8]

Well it turned out it was the ignition but not from a weak spark....basically the higher boost was putting me into an area of the ignition map i hadn't looked that closely at and it was way conservative. Pulled timing back to 13deg so basically it couldn't complete a burn and hence the miss....i should have picked the rich mixture but i did tweak up the fuel as a safety feature.

Anyways, have upped the ign and leaned off the fuel to a 12:1 a/f and it is back to it's wheelspinning best......on 17psi it is totally mad. A final dyno run Sunday week...stay tuned for an update on the current 320rwkw best as i'm pretty sure we are gonna totally smash that.

More for the nay sayers to ponder

 

[krayn]

17 psi, that would be a handfull to keep driving in a straight line when it hit boost!!!! I thought 12-13 psi was getting to the top end of what a un opened motor would handle. Your setting new boundrys for us unopend engine and boosted guys. Well done...keep us posted, mine started to ping at 14 psi and running 15 deg advance. I spose there are many variables in each setup.

 

[JustenGT8]

Tracks beautifully....full wheelspin in 3rd at 140kph onwards and still throwing me down the road, love that 2.9:1 final drive. Boost comes on reasonably linearly so the 'hit' is early a quite controllable. You do have to be on your toes if it's not straight as it'll step out at any speed

 

[WDoherty]

i don't know how you are pouring that much boost onto a stock motor without failure, amazing, can't wait to see the highest recorded stock internal 1uz numbers.

 

[JustenGT8]

It's called tuning Toyota's are tough...as long as you stay away from det then the basic structural integrity of these motors will take heaps. There is a limit of course and i must be very very close but tuning is the key.

Stay away from piggyback and even entry level stand alone if you want to produce efficient big hp. Autronic for mine but Motec is another obvious choice.

 

[bango]

It's called tuning Toyota's are tough...as long as you stay away from det then the basic structural integrity of these motors will take heaps. There is a limit of course and i must be very very close but tuning is the key.

Stay away from piggyback and even entry level stand alone if you want to produce efficient big hp. Autronic for mine but Motec is another obvious choice.

Which particular one are you using?

 

[dass]

Would be getting close to the limit. A friend of mine was making just over the 500 RWHP on a stock TT when he had a head-gasket let go and on closer inspection found he had a couple of bent conrods.

 

[Lextreme II]

Justen,

Perhaps you should upgrade the stock 1uzfe headgaskets to the 98-00 VVTi headgaskets. They are direct bolt in and MLS too.

 

[bango]

Would be getting close to the limit. A friend of mine was making just over the 500 RWHP on a stock TT when he had a head-gasket let go and on closer inspection found he had a couple of bent conrods.

Was this on a 1UZ pre 98 dass? Seems the rods sizes varies between the UZ's..

 

[dass]

It was an early engine . He has now done the same as me .Up-graded to 1/2" heads studs ,Agro rods, forged pistons Etc.

 

[bango]

Its interesting to hear about bent rods and melted pistons,in this case bent rods but OK pistons..thats 500RWHP too..the pistons did hold up right?

 

[200sx-v8]

Justen,

Perhaps you should upgrade the stock 1uzfe headgaskets to the 98-00 VVTi headgaskets. They are direct bolt in and MLS too.

Or mabe some kind of thicker mls gaskets to lower the cr at the same time.

 

[JustenGT8]

I've got copper gaskets, ARP head studs, etc etc etc all to go into the new motor. This one is staying stock to see what they can deliver.

Once i have my other proj car sorted on the road i'll be testing this UZ on the dyno until it pops. The Autronic makes tuning so easy...100 times quicker than any other ECU i have played with as it does so much itself with the target tables.

 

[fugly]

I think how you use your car also has a lot to do with how long the motor survives with boost, even at moderate boost levels, for example my engine didn't take to kindly to being trashed for a couple minutes in a burnout comp despite having a pretty safe tune 11.7 A/F's & 19 degrees advance, i'm sure it would have survived for years drag racing, street racing or dyno comps etc with that tune, melting pistons scared me into detuning (11.4A/F's,17 degrees timing, bigger pulley) the replacment engine for extra safety, it has survived one burnout comp since which made me happy.

 

[JustenGT8]

Except you forgot about my circuit racing. The car is as quick as Australia's premier racing class (on my local track) so it's not like it had an easy life. I do keep my laps to within what the standard cooling systems can take so that plays a big part.

Burnouts are very hard on cooling as airflow is pretty well non existent. Not my thing to be honest but i would build very different support systems if it was.