Project Thread Supercharged 1UZ Bangkok Drag Truck

[Fasteddie]

...hmmm...that sucks to have to back to cam checking etc etc...
Before my 1UZ went in, the engine builder checked, checked and double checked:
Hope you get things sorted out soon, good luck !!!!

 

[JustenGT8]

Seriously, pressurize your intake, you would be surprised what you might find.

Question, if you put your hand over the TB, does it die, or stay running?

Air has got to be coming from somewhere, if not the TB, then WHERE?

That's a dead easy check...cover TB and if it still runs it has a leak. 2 seconds effort to save you dicking around with the cams

 

[scotturnot]

I just spray starter fluid around the suspect areas when the engine is running, even a small injector leak will make the engine speed up when the starter fluid hits it.

 

[cribbj]

I have found that the cheaper (non-OEM) eBay type cardboard intake manifold gaskets are absolute cr*p and are prone to leak.

If you're not running OEM intake gaskets, or another quality type with a rubberised surface, I'd recommend that you get rid of them altogether, and go to either an anaerobic sealant, or something like Hylomar, which IMO seals as well as silicone, and does clean up with lacquer thinner, MEK, etc.

 

[HarperRacingBangkok]

Thanks guys for your helpful tips and good ideas. I understand your feelings that it MUST be a leak. But it is not. Yes, this is counter-intuitive: It runs with the throttle completely closed and blocked off. The intake has been off three times and proper gaskets and proper sealant used. The list of tests [everywhere there is a joint] for leakage is long and comprehensive (including all of the suggested methods from you guys, plus many you have not). There is no leak. Many knowledgeable racers/engine builders have been to the shop to help find the leak. You can imagine the hair pulling I, and they, have gone through - the bafflement - the doubt - the impossible to accept notion that it is running with no leak and the throttle blocked shut. . . . but it does. Yes, I know what you are thinking now: the tests were not done right, the reassembly was incompetent, the materials used were faulty, something was not checked. I have not been casual in my approach to finding the solution, nor cavalier in my efforts; many, many hours of painstaking effort has gone into checking for leaks in a very systematic manner - without finding any. I am still open to any other ideas.

The alternative reasons are radical indeed: too much overlap or bad valve seals/worn valve guides (yes, I know, there should be white smoke from the oil if it is the valves . . . .). I am checking the cams first (yes, it is possible, and documented, that an engine can run because of misindexed cams), and then a leakdown test (I have to borrow a leakdown test kit first). I'll know in a couple of days. Wish me luck.

 

[HarperRacingBangkok]

But, of course, we could have missed something.

 

[SuperRunner]

I had a very similar problem with mine and it turned out to be the manifold to head One one side it was not flush all the way to the head, even though it appeared to be. A pressure test revealed how bad it was actually leaking.

I ended up making my own double thick paper gasket. The stuff you get from the parts store that is pretty thick. I then coated all sides of the gasket with FIPG, then put a thick amount of FIPG along the top of the gasket where the majority of the leak was. I then let it set overnight. It worked. The problem would be the amount of boost you are probably going to run. I was only running 6psi at the time. My setup(now old setup) probably wouldn't have held as much as 15psi before blowing out the gasket.

Engine won't run without air. If not the TB, then where? If you were actually pulling in enough air through your cam/ and crank seals, there would be a fair amount of smoke, so I would scratch that out.

My CURRENT config also has a manifold leak. From welding on the top 1/2" thick plate for the supercharger it warped slightly. I put it on a belt sander, but there was one spot that I didn't get very well. I thought it would be ok. Nope, 4,000RPM idle. I put some clay along where there was still warping and presto, 2500rpm idle. The rest of the leak is from the bottom 1/2" plate that bolts to the lower manifold. I didn't think that it warped that much, but pulling it back off and putting a straight edge one it, there was just a tiny bit of warping that the gaskets could not seal.

Until you pressurize the system or other means of testing for leaks(starter fluid, smoke test), visual inspection is worthless, epspecially where the manifold bolts to the head. A TINY bit of warpage will cause a leak.

 

[HarperRacingBangkok]

I put some clay along where there was still warping and presto, 2500rpm idle. The rest of the leak is from the bottom 1/2" plate that bolts to the lower manifold. I didn't think that it warped that much, but pulling it back off and putting a straight edge one it, there was just a tiny bit of warping that the gaskets could not seal.

SuperRunner, thanks for the good and useful ideas. Even though I am loathe to admit it, there could still be a leak -- in fact, deep down, I hope there is a leak. I like your clay idea and will do it. I am still degreeing the cams . . . as this should have been done in the first place.

Thanks again,

Doc

 

[XR8tt]

Maybe do what the top fuelers do and run "O" rings between inlet & head ??...

Or apply silicon on both surfaces, assemble but don't tighten bolts [maybe finger tight?]
Leave over night or two or three hours.. Then torque manifold etc...
This way the silicon isn't squashed out where here's clearance..
Double check the PCV if still in use ??

 

[HarperRacingBangkok]

Rebellion Causing Project Delay

A small rebellion is going on in my home town, Bangkok, at the moment which is delaying my 1UZ racing project. I do not want to contract 45 caliber lead poisoning on the way to the machine shop, I think you would agree. Can't these people see that drag racing is more important than equality, democracy, and political reform?

 

[JustenGT8]

Just on the leak idea again I was pulling down my new stockie and 2 other sources for a decent size inlet leak could be the cold start injector hidden away underneath or the idle up valve.

Being alive and carless definitely beats being dead

 

[stevechumo]

A small rebellion is going on in my home town, Bangkok, at the moment which is delaying my 1UZ racing project. I do not want to contract 45 caliber lead poisoning on the way to the machine shop, I think you would agree. Can't these people see that drag racing is more important than equality, democracy, and political reform?

I've been watching & reading the news about the Red shirt party in Thai . There're a lot of political movements that lead to chaos going on over there right now. Wish you best lucks!

 

[XR8tt]

Check injector O rings ???

 

[HarperRacingBangkok]

Thanks for your concern. There is a real war raging in downtown Bangkok at this very moment . . . but I am a couple of miles from the city center. I hope today is the end of it.

Yes, I made custom aluminum washers (top and bottom) and found "perfect" rubber seals to assure injector seal.

All the holes not being used on the intake have been welded shut.

No need to o-ring the heads at only 8 pounds of boost.

I am machining the combustion chambers to lower the compression (taking out the "humps) and to lessen the possibility of detonation, as well as ordering a quality Cometic steel head gasket in a 1.3mm size.

More later.

 

[SuperRunner]

What is the thickness of the stock head gasket. You DO NOT want to run a thicker head gasket than stock, that is a bad idea. There is a reason why the HG is a certain thickness. Changing this will change much of the thermal dynamics of the chamber and can actually increase the chances of pre-ignition even though you are lowering your combustion pressure.

 

[HarperRacingBangkok]

The stock head gasket is 1.3mm. I ordered a 1.3 head gasket. Compression was lowered by machining in the combustion chamber, a not uncommon procedure on 1UZ high performance engines (www.lextreme.com/cr.html). Yes, at the start of my project I was using a thicker head gasket, but not now. There is no law of physics that would preclude a thicker head gasket, however. It (thicker head gaskets) is certainly not a good way to lower compression -- there can be problems associated with reduced quench turbulence and exposed edges that CAN exacerbate pre-ignition tendencies . . . but 8000hp top fuel engine tuners do it, F1 teams do it, and le Mans prototype teams do it (I was on such a team).

 

[SuperRunner]

Ok, just making sure. Combustion chamber or pistons is the correct way to lower compression. Personally I am a fan of high comp, like 10:1 and higher.

As far as those 8,000hp machines, I think at that point other laws apply, but I don't know anything about that.

 

[SuperRunner]

WHAT THE CRAP!!! DAVID!!!!

These pics just showed up in my post, I cannot even delete them, they are not even mine.

 

[cribbj]

Yeah, they're showing up more & more, and we mods are getting more & more tired of manually deleting them......

 

[Cobber]

They are great pics though...