Why do 1UZ heads suck soo bad, what can we do.

[Jaco]

Hi Plman.
Thanx for the pics.
This just goes to show that the 1uz heads responds very well to porting.
112Hp per liter souds very optimistic on factory cams, is this in normal aspirated form? must be forced induction.

 

[plman]

Hey Jaco,
No, just normal aspirated form, no NOS, just this product www.enerpulse.com, engine is balanced with these ported heads and factory cams. Good MPGs, 27 / 28 hwy, 22/24 intown. Cut 3/4 sec off 1/8 mile run. The 1uzfe VTTi is already a good engine and yes, heads respond very well to a little work. Most importantly is the more consistant power band across the board.

 

[MWP]

Maybe a little better understanding. A 78% flow increase, producing 112.5 HP per liter on factory cams. Air Technologies stated they were excellent heads for flow and can go much higher increase if wanted.

Is that a VVTI or non-VVTI head in those photos?

Doesnt look anything like the non-VVTI head unless its had major modifications.

The VVTI 1UZ heads are much improved compared to the non-VVTI heads.

 

[plman]

1998 GS400 VVTi heads, very good factory design, has lots of potential

 

[plman]

Jaco,
You were right, the 112 HP per liter was not correct, it turns out after test that it is 399 HP. 99 HP per liter, problem now is too much spin all the way into 3rd gear, if you can't get it to the ground and hook up you go no where.

 

[SuperRunner]

VVTI heads flow 230 out of the box. Non-vvti heads max out at probably around 140. HUGE DIFFERENCE!

 

[striker]

is that really true?

the vvti heads being so much better than the early heads?

David you stated that the VVTI heads fit on the early engine block, but wasn;t there an isue with the cam phasing actuator oil line not matching up?

I'm have the manifold for the early heads allmost finnished with the intercoolers inside but what would happen if it's finnished? surely i will need something elase to work on again? can't be sitting still now can i?

would be a nice upgrade for the future if this deems true!

grtz Thomas

 

[plman]

factory head flow VVti

factory CFM flow
169.4 @ 150 lift
212.0 @ 200
249.5 @ 250
195.9 @ 300
196.8 @ 350

Inproved flow after little work: street work can go higher easily
172.2 @ 150
226.5 @ 200
259.8 @ 250
271.9 @ 300
281.0 @ 350

98 and above oil channels were changed and improved

 

[striker]

excuse my ignorance but, where there pre 1998 VVTi heads?

you don't see 1uzfe VVT engines overe here in holland at all! so never come across one.

basicly the question should be, which VVTi head would my 1992 1uzfe non VVT engine.

grtz thomas

ps anyone know the bore center of a honda K20a engine....

 

[cjsupra90]

Thomas, 98 was the first year of VVTi for the UZ. 97 and earlier had all the same heads. There was a cam change in 95 or 96 (dont recall which year)

Any of the 400series VVTi head will bolt onto the earlier block as it the 430series VVTi head. The oil supply for VVTi actuation is the problem. The early blocks do not have the casting buildout in the valley where the oil supply is taken from on a VVTi engine. This could be solved though with some braided stainless lines and a bit of drilling and tapping...

On problem that has been brought up but I have not seen proof of it yet is at full advance, the INTAKE valves will interfer with the stock non-VVTi pistons. So either VVTi pistons have to be used or a custom set with the proper valve relief are needed....

I've been trying to come up with a set of VVTi heads and verfy whether or not they do interfer at full advance and figure out what the maximum advance is that could be used to prevent interference. Modifing the actuator to limit the amout of advance would not be hard.

 

[plman]

98 VVti

I have the 98 VVti one for sale if needed. When pulled ran great with no problems, heads are off, bottom end in tack. There are just over 150K on engine, always used syn oil.

 

[cjsupra90]

I have the 98 VVti one for sale if needed. When pulled ran great with no problems, heads are off, bottom end in tack. There are just over 150K on engine, always used syn oil.

What would you like for them?

 

[striker]

thanks for clearing that up chris!

the oiling issue is easily overcome.

if you even figure it out, please drop a line!

Grtz Thomas

 

[plman]

98 heads

600 can throw in insured shipping with that

 

[cjsupra90]

I'll keep that in mind. I have a local wrecker that has a left side complete head and said they can probably get me the right side comeplete for 200 per head. Money is tight at the very moment so I cant buy anything until probably next month. 600 shipped from GA to me in FL is not a bad price so if the wrecker falls through, then I'll get intouch with you when I have the extra cash and see if you still have them and are willing to part with them.

 

[cjsupra90]

Thomas, I'll definitly keep you and everyone else updated once I have a the heads and have some hard facts on them and about interference issues....

 

[scotturnot]

Since John has not stepped in on this here is important info in his thread.
http://www.lextreme.com/forums/showpost.php?p=100800&postcount=388

 

[SuperRunner]

So it turns out I am COMPLETELY WRONG about the non-vvit heads.

I never actually did flow test, the 160cfm data I got was from someone else...I don't even remember where(long time ago)

Anyway, I plopped a head on the bench today and was rather impressed.

Here is what I got.

.100 92.3
.200 155.5
.300 199.1
.350 206.7
.400 214.3


this is a 2J

.100 91
.200 161
.300 197
.350 206
.400 210

So the non-vvit heads flow just as well as the 2J, at least on the intake side. I will need to check the exhaust out later.

 

[4000GT]

yeah thats about what we flowed, then got to 260CFM on the intake after some shaping.

 

[cribbj]

I would be leery of those numbers. The figures you show for the 2JZ look to be in the ball park, but the 1UZ's are around 50% higher than two sets of stock 1UZ numbers we've seen in the past. Did you actually run the 2JZ and 1UZ heads side by side?

You're saying that you found a stock non-VVTi 1UZ head flows within 12% of the big valve, highly ported head that RMS built for a 10,000 RPM capable, naturally aspirated, race engine?

What pressure differential were you running?