1uz head seal vs 2uz iron block strength @ 30+PSI

[M3TURBO]

Wonder is anyone using the 2UZ iron block with 1UZ heads or indeed the 1UZ with high boost reliably, say 30PSI +? Sorry if some of this content may be covered already in the forum.​

I assuming fully built internals - combo from David, so apart from weight, are there any issues with the it? I am wondering if it is worth the investment & hassle. Or is the limiting factor the 1UZ heads.

Reason for query, for some reason, yet to be resolved, we are having head gasket sealing issues even at only 24psi (800HP region) with the 1UZ alloy block, 7/16" ARP studs torqued to 80lbs, MLS gaskets, surfaces machined flat. I summise that something is giving either block or heads, and Im worried to go 95+lbs torque, fear of block local deformation or thread failure with the alloy block. Reckon we could go with 110Lbs on an iron block like we use on the 2JZ.

I am going to try 1/2" ARP studs from David on another engine but if these don't work then the other dread is that the chambers are lifting, (heads deforming between the studs under high cylinder pressure) if so we have no options, only go back to a 2JZ.

Not sure if I fancy going to metal "O" ring, groove & copper gasket method, becuase if it's an inherent head or block weakness problem this will not help.

Any experience & comments will be much appreciated.

 

[XR8tt]

What are you using for tune ??
ECU, turbo specs, compression etc..

 

[M3TURBO]

Basic specs are:

Ross/Carrillo package 6sp Supra box, custom flywheel, 4 plate OS Giken.
CR=8.5:1
Autronic SM2 - 1.93 + R500 CDI .
Small solenoid boost control valve.
8 x Bosch coils
Autronic AFR meter + Uego.
Single Garrett GT45R + 102/76mm compressor wheel, 1.22 AR.
HKS GTII Wastegate
Headers = 4 into 1 each side 2” primary’s, 3.5” secondary’s,
Single 4” outlet pipe at front of car
Fuel = Toluene based race gas, was using Avgas.
8 x 1000cc denso’s, standard rails, HKS FP regulator
2 x Bosch 044 fuel pumps.
Big intercooler + aquamist.

Ported heads, standard valves & shims, titanium lifters, race springs, Kelford 272/272 cams ([email protected]”)– but they came with centers a country mile out. I had to make some vernier wheels and custom exhaust cam gear to move the centers, Now at 112/116 in/ex

One of my worries is the EPB is quite high, typically 2 X boost pressure, eg 1.5 boost gets 3 bar exhaust. Need a bigger turbo.

On boost, Lambda λ still safe, Ive got it at 0.74 at 1.5 bar 5K , 0.77 at 8.5K.
Intake temps run at 40 to 45 C. without the aquamist on.

2 x Bosch knock sensors, Knock link/head phones.

Once I get the gasket seal sorted I would like to put the cams on 114/110 centers but only after a bigger turbo, looking at a S400/80mm to get the EBP down. The plan is to go to 2.0 + Bar boost. The current GT45 turbo is maxed out flow-wise at 1.6bar on this set up.

Opened the engine to fix the gasket problem, pistons, plugs, valves all perfect no signs of det.

I have just put some TimeSert’s in today on some stud positions and intend to go with 100lbs stud torque on the 7/16” ARP’s.

Thanks for any feedback,

 

[spf_lexus]

The 1uz heads flow better than the 2uz heads, thats why the combination (4.7 and 4.0 heads) creates it's own little monster setup. Did you run the cometic gaskets?

 

[M3TURBO]

I am still using a 1UZ alloy block at this point in time. Sorry my first post may have been misleading. Yes I’m using Cometics/MLS gaskets, I was only thinking of going with the iron block if there is any significant advantage such more strength under high boost and a better head gasket seal situation. Of course the extra cc’s would help too. I have ordered some SCE gaskets too.

The iron block might not be necessary, I hope, as long as I can get the heads to seal properly under boost. Note I’m also considering the 1UZ with bigger sleeves option for a next step.

 

[cribbj]

I would not waste the time or money on 7/16" studs. There is just not enough material left in the block to do a good job retapping the existing 10mm stud holes for 7/16".

I would go for either 12mm or 1/2" studs, plus tap the block deeper than the OEM studs. My engine has this configuration, with Cometic MLS's, and we've probably made 15+ WOT runs with it at 18-20psi on the engine dyno, and have seen no signs of the heads lifting.

If I were going for much higher boost, say 25 or 30 psi like you're doing, I'd o-ring the block. This company: http://www.helicoflex.com makes a gas filled o-ring in stainless steel or alloy. With the gas filled construction, they don't take a permanent deformation like a copper gasket does, and they are apparently being used with very good success in highly boosted engines. If you're interested, PM me, and I'll put you in contact with someone who has had experience with these.

I really think o-ringing the 1UZ block will be the only effective way of sealing these engines for ultra high boost, since they're only a 4 stud per cylinder configuration. If we had 5 studs per cylinder, it would be a much easier engine to seal.

Having said that, even the mighty 2JZ only has 4 studs per hole, and to make matters worse, it's a loooonnng cylinder head, too.

 

[Fasteddie]

Any pictures of your setup ?...spec wise its quite a lot !

 

[M3TURBO]

Thanks for the tips cribbj, I have some ARP 1/2" studs on order. I will finish up with O rings if necessary. Your right it makes sense the 2J head can take high boost, so why can't the 1UZ with the same stud to bore ratio. I might be in touch with you again.

Some pics, the installation is kind of experimental so it is not so tidy, few more changes since these pictures were taken.

 

[Lextreme II]

Wow.. u r running CNP.... nice....

 

[cribbj]

We're all learning what works and what doesn't with these 1UZ's. That's good intel about the Kelford cams. Did you modify the OEM exhaust cam gear, or make a new one to get the lobe centers you wanted?

You have a great project there; I'm doing something similar, but with a supercharged 1UZ into a Supra chassis. The 2JZ just didn't have enough torque for me.

You're obviously after HP; have you considered a set of twins instead of the big single?

 

[JBrady]

Single Garrett GT45R + 102/76mm compressor wheel, 1.22 AR.
HKS GTII Wastegate
Headers = 4 into 1 each side 2” primary’s, 3.5” secondary’s,
Single 4” outlet pipe at front of car

One of my worries is the EPB is quite high, typically 2 X boost pressure, eg 1.5 boost gets 3 bar exhaust. Need a bigger turbo.

On boost, Lambda λ still safe, Ive got it at 0.74 at 1.5 bar 5K , 0.77 at 8.5K.
Intake temps run at 40 to 45 C. without the aquamist on.

2 x Bosch knock sensors, Knock link/head phones.

Once I get the gasket seal sorted I would like to put the cams on 114/110 centers but only after a bigger turbo, looking at a S400/80mm to get the EBP down. The plan is to go to 2.0 + Bar boost. The current GT45 turbo is maxed out flow-wise at 1.6bar on this set up.

Opened the engine to fix the gasket problem, pistons, plugs, valves all perfect no signs of det.

Not sure exactly what turbo you have. Garrett lists the 102mm compressor with its GT42 and a 108mm with the GT4508R.
http://www.turbobygarrett.com/turbobygarrett/products/turbochargers.html#Large

That said you may not have seen this from a previous post of mine. OHV V8, aluminum heads and block, 4 bolt/2v/cyl heads, 44psi boost, 7800rpm
http://www.popularhotrodding.com/enginemasters/articles/pontiac/0410em_butler/index.html

Now, considering the above consider the exhaust headers. 2.00" primaries, 2.50" collectors.

Consider the power 2886hp 2105tq at 7200rpm (the LOWEST rpm they could take a reading on as the dyno could not hold the torque)

Now, I submit this to make a point. Since the turbo will always be the greatest flow restriction it begs the question how large to make the primaries and collectors? The larger the area the lower the speed and higher the pressure and higher the temperature loss. This becomes a restriction in itself and lowers efficiency. Better to reduce the primaries and collectors and increase the turbine. This works the engine less.

Another concern is your factory intake. The losses inside mean more work. If you haven't seen the work of forum member RMS you should search.

One more pic of this monster Pontiac

 

[XR8tt]

Yes I would have used 1 5/8 with maybe 1 7/8 for the first 30mm..
Bigger exhaust housing..?? I'm fitting up an Airwerks S475.
It could still be in your tune ?and turbine size as there's a little too much back pressure..
O ringing is FINE if done right... Too many just O ring without proper application..

 

[M3TURBO]

That’s some nice reading, will study it.

The Garrett GT45 Turbo I have has a comp wheel fitted from a GT42, this was done by our local Garrett dealer. They didn’t have the 108 wheel available. I have several combinations that I’ve used in the past= GT42+94/70, GT42+102/76, GT45+94/70 and GT45+102/76.

Don’t think a bigger housing will enough help. Out of interest I saw no virtually difference in EBP between .84, 1.05 and 1.22. I think the small turbine wheel is the biggest problem.

Yes agree myself, I might have gone too big on the primary’s and secondary’s too. Though the local Evo tuners insist on 2” primary’s, 4 cyl 2.0 litre. 650HP. I know different case, length, head flow etc.

Point taken about the stock intake. I have a new intake plenum under construction to address the issue, see pics, short direct runners and a bolt on billet top section with 100mm throttle body.

I was considering twins, but more likely to go with bigger single, will be more efficient if I can get hold of the right turbo, S480 looking interesting, twins would mean more work on the install and getting two wastegates set up. A single simplifies things. Though twins would cut down the effective header length and be easier to obtain locally.

I modified the OEM cam gears, see pics, these have 3 precisely machined extra slots 3, 5 & 7degrees at the cam, of advance over stock slot, I’m now on the 7deg slot! But don't forget it has to compensate for intake cam adjustment too. OEM intake sprocket is modified see pic.

 

[scotturnot]

Wow, this is a impressive build! What you have done to the cams is something I have been thinking about a lot lately, Nice to see it being done.

 

[XR8tt]

The inlet won't IMO give you head lifting issues ?? Unless compressor is outside its efficiancy and blowing hot air??
Detonation will . Which can be caused with exhaust not scavenging completely on exhaust stroke..
Yes I have twin turbo T3/4 Precision 61mm hybrids on 5.4 Ford Windsor ..Went from 69 trim to 76 trim on .63 A.R housings.. Believe it or not it only gets to 30Lb back pressure at 18 Lb @ 6500 rpm ..650 rwhp.. With the 69 trim it was over 40 Lb [Pegged gauge] and at much lower rpm... The A.R is not the only equation as said..

 

[M3TURBO]

Yes the intake its self is a little off-topic. However, I wonder at which point does the stock intake, throttle & long dog leg runners become a significant restriction? Without test data etc I guess it’s probably OK up to the 850 hp region?

A restrictive intake is going to require more boost to overcome its pressure drop. E.G. each extra 1psi needed for the intake would mean about 2psi of extra unnecessary exhaust pressure to fight against; this definitely relates to exhaust scavenging and det threshold. Not a lot, but every bit helps.

 

[stevechumo]

I believe the cam sprockets are adjustable for timing. I see some adjustabel cam sprockets but wasn't so sure how it works.

 

[Full-Race Geoff]

i lurk on this forum and just saw this post. i design and mfg turbo systems for a living, at www.full-race.com and i am confident in telling you that your problem is excessive backpressure!! that is why you are lifting the cyl head.

its not a big deal at all, you just need to get the backpressure way down with a different turbo setup. you will make tons more power and it will be easier on the motor.

my good friend and I are going to start building an sc400 dedicated drag car to battle our 2jz friends, great to see builds like this!!

 

[M3TURBO]

Thanks Full-Race Geoff.

Yeh we pretty much figured that back pressure was a major part of the problem, Im keeping the boost down for now until I procure a larger turbo. Other than that Ive got things under control for now, new design MLS gaskets, new threads in the block and the use of much more head stud torque, - 100lbs. No problems so far at the 20psi level.

Hope to hear more about your project, lets keep in touch.

 

[spf_lexus]

Hey M3, I rebuild my heads and used std size 10mm arp head studs. I torqued to 75lb, did you use 7/8'' studs for that torque?