Project Thread Supercharged 1UZ Bangkok Drag Truck

[JustenGT8]

Yup go forged. Piston rings lands normally fail before the rods, so you'd normally upgrade to forged pistons and the question would be whether to go rods as well

 

[HarperRacingBangkok]

There sure is a lot of different thinking out there about these 1UZs. I just broke a standard 'big' rod on the dyno, so I bought some forged steel rods, but I am still toying with building a 2UZ short block down the road and I do not necessarily want to buy forged pistons for the 1UZ now, and then another set for the 2UZ later. The advice is mixed: forged rods + standard pistons are good for my combination - or forged pistons and standard rods are good. Best is forged rods and pistons. Perhaps my phased plan (get it running as a standard 1UZ, then build a race short block) is not feasible. You can back read this thread or go to my web site for details on my combination (6 pounds boost, 50hp NOS, 264 Kelford cams + good springs, head 'humps' milled off, 565 injectors, AEM stand-alone ECU). Your input is welcome . . for me and the other owners of 1UZs who are in the midst of a build/modification path. It looks like the standard rods, even the big ones, are not stout enough - or the QC is not consistent enough, to warrant their use without risk. My motor did not detonate, go lean, hydrolic, or misfire. The rod broke under power . . . and not all that much (or as much as others' with more reported HP on this forum).

 

[XR8tt]

Trust me there's NOTHING worse when your giving the engine some and your thinking about durability !!! Cheap insurance once it's done...

 

[Zuffen]

Given the cost of pulling an engine down, the cost of forged pistons is minor.

You'll need to buy new rings and hone the engine to do it properly with this rebuild.

A set of rings will cost you (say) $300.00 and a set of pistons with rings maybe $1,250.

Given the cost of head gaskets and bearings I would think it would cost you well over $1,000 just to replace a damaged piston, without counting the re-hone cost.

Do it now whilst it's apart.

Do it once do it right!

 

[Cobber]

Skimming back through the posts I presume this is the same engine that had massive problems with a cross firing ignition, crossed wires during first start up etc etc. A spark at the wrong time will easily break / weaken a rod.

5-6 psi on a std motor is very little stress, Nos can create it's own problems but also very manageable on a std engine with the right tune parameters.

I'm a big fan of boost the hell out of a std engine and then replace it when or if it blows up.

I'm up to 13 psi now with water meth injection and loving it, the only thing I have done to the engine is replace the plugs for 1 range cooler and change the cam belt.

I'm thinking you were just a bit unlucky.

 

[JustenGT8]

NO WAY did power kill your engine.....take my experience with as many grains as salt as you wish but a totally stock engine ran for 5 years!!!! and barely an easy km in them. In that time the LEAST power it made was 255rwkw....it generally made over 300rwkw with a few dyno pulls and crazy track runs at 400rwkw. It also ran 25psi for a month or so with a heap of dyno pulls at that boost!! These weren't street runs showing off to mates, this was serious track time on boost for multiple laps at a time.

These engines are TOUGH when tuned right.

Current engine is running 16psi of roots blower and making 270-280rwkw with WI only...running on E85. Totally stock and so far survived 5hrs of dyno time, one track day and 2 hillclimbs....that's equiv to about 10yrs of drag racing

Best option for you is just buy another cheap stock engine, swap your good bits over and you should be right for years of trouble free running...IF your probs are solved?

If you are going with a build then do the lot....selling the proven package when you decide to move on is always an option?

Otherwise just bolt your SC to an LS1 and be done with the UZ

 

[HarperRacingBangkok]

The plan

Thanks again for all of your time and interest. I really appreciate it. There appears to be quite a variance in opinion, and experience, as to the strength, and horsepower limits, of the standard (large rod) 1UZ bottom end. Some compliment their own good tuning for the reliability of their motors, while others claim bad luck for broken parts on well tuned 1UZs. And there have been some broken parts because of mistakes. I believe all groups. So, now I have to make a decision. I do not have unlimited funds for an 'ultimate strength' combination, but I have some petty cash. Here is what I am going to do now: I have found a good rebuild-able 2UZ bottom end (in "up country" Thailand). I will use my current intake, supercharger, heads (it is good, but needs two new valves, which I have), deep oil pan, camshafts/springs, and head studs with this 2UZ short block. Amazingly, I found and purchased a set of Lextreme steel rods and Calico bearings here in Bangkok. I will check (and correct, if needed) the 2UZ crankshaft and bore/hone the block .030 over (292cu.in), get ARP main studs, and order the appropriate forged pistons in a 10.5 or 11.0 compression - because I have taken the humps out of the combustion chambers and have only 5-8 pounds of boost on race gas. I will order another set of 1.3 Cometic steel head gaskets (I have sold the 1UZ set already). I was already at 85% duty cycle on my 565cc injectors with the dry NOS, so I will also get new 1000cc injectors (for MORE NOS!). For future use, I am also negotiating for one of those high flowing New Zealand single plane high rise manifolds converted to EFI . . . . . SO LOOK OUT! Wish me luck! I hope you haven't run out of it yet!

 

[JustenGT8]

Sounds like a plan but i have a suggestion. The 2UZ heads should kill the UZ heads for flow so sell your current Kelford setup and run the full 2UZ top end. The 2UZ intake looks pretty good as well but if not then it's a simple bit if fabrication to put a new top on it.

 

[spf_lexus]

Ever since John mentioned swapping the vvti manifold to the early uz I have been wanting to try this. The only variable is the mounting angle (where flange meets the heads). I think if you cut the manifold in half close to the bottom of the runners... and then cut off 15 or so degrees and re-weld, it should fit. You would also need to swap throttle bodies.

By swapping manifolds, you get short and long runners so its perfect for street use and drag/track.

 

[JBrady]

Ever since John mentioned swapping the vvti manifold to the early uz I have been wanting to try this. The only variable is the mounting angle (where flange meets the heads). I think if you cut the manifold in half close to the bottom of the runners... and then cut off 15 or so degrees and re-weld, it should fit. You would also need to swap throttle bodies.

By swapping manifolds, you get short and long runners so its perfect for street use and drag/track.

How about a set of pre-vvti 2uz heads instead of cutting and welding. The heads would flow much better than the 1st gens and the manifold would bolt right on.

 

[spf_lexus]

How about a set of pre-vvti 2uz heads instead of cutting and welding

Nice find, I assumed the early 2uz had the same manifold. If its angled then it should be a nice and easy experiment. I'll keep my eyes open for one.

 

[JustenGT8]

Getting any 2UZ manifold onto the non VVTi 1UZ heads would be a pretty sizeable challenge....more difficult than fabricating from scratch and hardly worth the trouble unless you were dead set on a 'factory' look?

 

[HarperRacingBangkok]

Plan B/2

Plan B/2: Since it is going to take some time to get all the pieces together for my race-prepped 2UZ short block (rods and pistons and boring/honing), I have decided to put my racer back together with another standard 1UZ bottom end I already have so I can go racing. Everybody who has looked at the motor with the broken rod can confirm that there was no evidence of overheating or detonation or leaning out or hydrolicing on that or any other cylinder. All the saved data confirm this as well. There is a race on December 4th I will try to make. Wish me luck.

 

[XR8tt]

Trouble is your possibly at the limit strength wise..

 

[HarperRacingBangkok]

Yes, that is the risk: max power strength. I have reflected on my dyno experience in the light of some new information: The dyno guy had the resistance of the rollers still set to the 1000hp turbo LS1 Firebird from the week before, and, the wiring guy made some mistakes, one of which, I now know, was to wire the trans in permanent OVERDRIVE! So, I have re-computed the dyno horsepower based on my race car being in Overdrive on the dyno: the new numbers are = 367 RWHP w/o NOS . . . + the 40hp of NOS = 407 RWHP. Assuming a 20% loss through the auto trans = 440 flywheel HP w/o NOS and 488 flywheel HP with NOS. Hmmm . . . . maybe that 40hp of NOS while the motor was making 440HP was enough to break the standard rod under the load of the overdrive gearing and the extreme dyno resistance? These numbers seem more realistic when compared to the injector size and recorded duty cycle. What say you?

 

[XR8tt]

Yep..
Starting to make sense now...

 

[M3TURBO]

Not necessarily,

High resistance roller setting, will not change your HP figures, if anything it might actually improve dyno HP numbers!

Modern dyno’s like this compute wheel torque against engine RPM to arrive at HP, it doesn’t matter if you are in 1st gear or 6th + overdrive,. And again the higher the gearing the better the Dyno HP figure might be. Generally it’s done in the 1:1 gear having the least gear friction loss. We once tried my 1UZ in 6th and got a slightly higher HP reading than 5th , also 5th gear figures higher that 4th for given boost levels.

If the dyno was set to an extreme load, then you would have known about it, even then if the motor can’t take it there is something wrong. As you know best tuning is usually done against a full braked dyno at different rpm steps.

Something is clearly wrong for the rod to break at this HP level and as mentioned earlier post, it looks like the piston broke before the rod or at the same time. The rod break is not a brittle fracture, but looks like it was torn apart and has secondary adjacent tensile cracks. nor has the gudgeon pin seized, that’s still free on the little end.

I would be looking into why you having to go with 85% duty on those 565cc injectors!

Hope this helps.

 

[XR8tt]

I would say the crank counterweight smashed the piston ??
Need pics of other side of rod..

 

[HarperRacingBangkok]

Hmmm. I did not mean to imply that I recomputed HP because of (or based on) more dyno resistance, although there is a relationship. It would seem that a 900hp engine on "not enough" dyno resistance would show more HP when there was more resistance. Of course a 400hp motor might not show the same improvement, or perhaps a decrease, if the dyno resistance was placed at the 900hp engine's optimal dyno resistance. I recomputed the HP substituting the overdrive gear ratio in place of M3TURBO's estimated gear ratio in his own equation. However, the overdrive gearing and the "too much" dyno resistance would surely have an effect on the stress placed on the rods: imagine a race car pulling a trailer full of rocks up a steep hill in overdrive at WOT then hitting the NOS. I am putting another standard 1UZ bottom end in the car now . . but very carefully inspecting every component. I accept that there could have been a micro second event that caused the rod to break . . . but I haven't seen any actual evidence yet of what that might have been. There are several highly plausible theories about what caused the rod to break and I am taking every effort to rectify those causes in the rebuild. I am as puzzled as anybody by the (perfect) AFR-to-injector-size-to-RPM-to-displacement-to-duty cycle computation which comes out to around 500hp - timing, cam timing, spark? We had no black smoke or raw fuel coming out the pipe, so it was getting burned. We'll see how this motor turns out.

 

[HarperRacingBangkok]

Since I am waiting . . . . .

I have never been really satisfied with the way I decided to solve the torque converter mounting problem (1UZ bell housing to mate my1JZ torque converter and race modified 1JZ A342 trans). Since my racer is [still] down getting another short block put in, I felt this was a good time to "do it right" . . . well . . . sorta right. THE RIGHT WAY would have been to get a proper 1UZ race torque converter. But, you know, time and money . . . . . What I will do now is to make a drive ring adapter out of forged aluminum to go between the flex plate (or ring gear, if you will) and the torque converter. This drive ring is essentially a very big and [correctly] thick washer or spacer. The bolts will go all the way through the flex plate and the drive ring into the torque converter pads. No more stands and gussets welded to the flex plate. I found the drive ring idea on the [Aussie] Castlemaine Rod Shop site (very good drivel ine products) as a part of their 1UZ-to-Powerglide/TH350-400 adapter. See the photo below - the drive ring, at the right thickness, will take care of all strength issues. I already have the "extended" torque converter locator pilot bearing to catch the front "knob" on the torque converter -- and another flex plate. The adapter plate, of course, is not necessary with the 1UZ bell housing. If you are wondering how to mate your 1JZ torque converter and trans to a 1UZ, this is a good way to do it.

Photo from the Castlemaine Rod Shop site.​