UZZ32

I am reading a book called "21st Century Performance" by Julian Edgar at the moment.
You can buy it from the www.autospeed.com site in the shop.

Anyway there are two particular chapters with very interesting information on the 1UZ-FE V8.

The first chapter "Engine and Driveline" part "camshafts" has a whole section about the 1UZ-FE camshafts and how they compare to other high performance engines. Standard specs are listed and they model changes (using Dyno2000 software) to the cams and resulting horspower increases.

The most effective would seem to be changing the standard exhaust cam for an exhaust cam with revised opening of 55 degrees BBDC (Before Bottom Dead Centre) and closing of 18 ATDC (After Top Dead Centre) (standard exhaust is 46 BBDC and 3 ATDC). This changed exhaust cam with the standard intake increased the horsepower from 260 to 300 !! (modelled on Dyno2000).

Although changing the exhaust cam (getting it welded and reground?) doesn't sound like a simple job.

The second very interesting bit is head porting. A 1UZ-FE head is flowbenched before and afterward being ported. Increases in flow on the bench usually relate directly to horsepower increases. After porting the intake flow increased by 19 percent and the exhaust by 14 percent!!! These are actual flow bench figures. Not only that but there are 12 full colour photos of before and after closeups of all the critical parts to pay attention to when porting. An extimated 20 hours was spent porting both heads.

I haven't heard of anyone ever trying different cams (only a supercharged 1UZ-FE, Ivan Tighe did those) or porting the heads for a street car -

Anyone heard anything or given it a go?

Isaak

Those changes will increase the horsepewer, but from what I remember from my modest racing past they leave torque ## the same. In other words, if you have 2-3 passengers with you in a car it will feel just like before the mods have been done.
The most challenging aspect of this mod is to actually find the shop which will be able to perform the high quality job, expecially with cams. I think the best solution is to get camshafts with altered/enhanced lobe profile directly from the factory, of course if they exist... . Changing lobe on existing one (welding and polishing) may have very short life expectancy and if failed will require the half (or more) engine parts replaced.
Porting and polishing cylinder heads for improved airflow on GS300-400 motor could be also extremely complex, since I suspect, it is already close to a limit from the factory. Again, my first choice would be to go with factory performance part, or factory backed racing team.
In both cases we're talking big $$ and top race mechanichs to do the job.
P.S. All these changes will require new/ reprogrammed ECU... .

QBranchCars

Like Isaak said, these modifications are probably best left for the factory, for instance in the pursuit of a M5-type N/A GS. However, in Japan, TOM's developed an engine kit for the 1UZ-FE 4.7L, for the Celsior. It includes forged piston, carved crankshaft, 0.8mm metal gaskets and a TOM's ECU. Cost is around 2,000,000 Yen (not sure if it includes labor).

I heard there was another Japanese company called "C" that made a similar kit.

As HP per $ is fairly high, most people will opt for the forced induction route, simpler and cheaper.

mayandoom

Though the camshafts on the V8 is complex , they can still be welded and polished by a competent machine shop and will still be as strong or even stronger than a grind billet camsahft IF DONE PROPERLY. That is the key ingredient. I do wonder how the VVTi and ECU will react to such a setup. Still alot of cash.

GlobeCLK

iTrader: (5)

well if memory serves me correct, the 260hp 1UZ-FE is the old 4.0 V8 engine used before, without VVTi. So yeah for older V8s (Japanese UZS143 I assume) or Soarer V8s, this would work. But for GS400s with the VVTi 1UZ-FE it won't matter because there's VVTi cams (I don't know about exhaust side though)

or I could be totally wrong.

LexusRules

VVT-i is intake only thats why u can change exhaust cam gear

Wheel Kinetics

Speaking from experience, be very very careful when changing your cam(s). Most people don't realize how much cams affect the engine. Outside of displacement, they're the most radical change.

You can easily gain 30-40 HP from cams. The problem is what do you lose? In general, you will lose low end. (What VVT-i, VTEC, etc saught to stop) You lose low end because your intake/exhaust valves overlap for too long at low engine speed which simply blows air through the engine. During higher RPMs, the engine "breathes" better with the overlap as it ingests more air. You also lose emissions, idle quality, and a quiet exhaust.

Unless your Lexus is a pseudo racecar, please leave the cams alone. And for the record, I am HKS 272 (i/e) equiped.

UZZ32

My exhaust cams were finished today ! - should get them back next week then another week to see if it was worth it. Read the story so far on my site.

SCV8

Has anyone checked to see if the intake cam is has more duration than the exhaust cam,and check to see if the two are in any way interchangeable?
I've done this to another vehicle with success,and saved hundreds of dollars compared to the "sport cams" offered for that car.The emissions are largely controlled by the exhaust cam timing.

UZZ32

Intake and exhaust cams are very different - see site for photos.

Modified V8 exhaust cams are back and in the car. But there has been a small hiccup.......

JPI Racing

Peter,
I know this is an old post but I never see the final dyno result from your upgrade.
JPI

JPI Racing

I have the 280 HKS on my race car and it idle almost like stock. We had to raise the idle up to 1000 rpm.
JPI