Polishing the ports will help prevent or reduce carbon build up over time...

My intake wasn't bad but have seen a 1998 with considerable buuld-up where the intake mates with the cylinder head. perhaps due to using 87 octane fuel.or low detergent (cheap) gas.

Probably all intakes in service 20 years + would respond well to cleaning....hoses, gaskets etc.

Will post a list of dealer parts used for this project.

 

Woops I guess I missed that one on the other page. Looks like it helped a bit.

 

20 HP and 25 ft pounds of torque under the curve is more than a bitn

By the way....thie ncrease is rear wheel horsepower ( not measured at the crankshaft)...so crankshaft H.P. and torque figures as advertised by Lexus in sales brochures are much higher;
than before extrude hone dyno rear wheeln HP, so it stands to reason the after extrude hone crank H.P. will be proportionally higher Iin relation to advertised H.P. as well.

 

[QUOTE=YODAONE;9910219]20 HP and 25 ft pounds of torque under the curve is more than a bit.






By the way....thie ncrease is rear wheel horsepower ( not measured at the crankshaft)...so crankshaft H.P. and torque figures as advertised by Lexus in sales brochures are much higher;

Ss it stands to reason the after extrude hone crank H.P. will be proportionally higher Iin relation to advertised H.P. as well.

 

[QUOTE=YODAONE;9910223]
McGrath Lexus compiled the following list of parts used for this project...

I overdo it a bit because I replaced every nut, bolt, seal , gasket, fuel dampers, vacuum valves, coolant and vacuum hose that was removed during extraction of intake...but it is complete.

 

Thanks Yoda for the excellent write up! It seems you've spent less than $2200 parts and honing and gained 20hp and 25 foot lbs of torque thats not unreasonable, I dont know what your 0-60 1/4 mile track time increases are but guys spend far more that that to gain less than one second. Thanks again for all the pics data and your knowledge!
John

[QUOTE=YODAONE;9911079]

 

[QUOTE=JJDAG;9918871]Thanks Yoda for the excellent write up! It seems you've spent less than $2200 parts and honing and gained 20hp and 25 foot lbs of torque thats not unreasonable, I dont know what your 0-60 1/4 mile track time increases are but guys spend far more that that to gain less than one second. Thanks again for all the pics data and your knowledge!
John

The project can be accomplished for $150 in parts + extrude hone costs

 

[QUOTE=YODAONE;9919143]I have an extra stock intake manifold should anyone wish to install an extrude honed intake and does not want to incur downtime...

Here's how that could work;

I send my istock ntake to Extrude Hone...you pay shipping.and Extrude Hone.

You either pay for the extra intake or send me yours (certain items removed)

P.M. me as to your interest.

 

This is great. FYI, both charts are SAE corrected so temperature, atmospheric pressure and humidity variations SHOULD be calculated into the final results (again, should be, I assume the operator has all the sensors hooked up and working correctly). Dynojet numbers are very, very consistent in this regard and is why they are preferred when comparing results especially between different dynos and locations.

Also, $100 per horsepower is a VERY reasonable number -- I can tell you this from years of modifying modern FI cars. Great to see on the LS400 where performance mods are few and far between, and most true power adders beyond a handful of HP are >$100/hp, even turbo kits.

@YODAONE

Would have been neat if you put a scanner on the ODB2 port and checked out the before/after short and long term trims. I wouldn't be surprised if they aren't much different since your MAF sensor does most of the work.

Given the big increase in your efficiency, I'd place money on a bet there's alot more power left on the table waiting to be unlocked on your car by an ECU retune (cam advance, timing, fueling) which unfortunately I believe is not possible on these cars.

 

The extrude hone process is $610. Replacement intake manifold, water crossover gaskets and miscellaneous about $150(or reuse what you have).so to/from shipping total is about $100
Dyno shows 20 rear wheel horsepower and 25 ft pounds of torque under the curve....so cost figures are $30-$50/HP...provided you are mechanically inclined.

Great project when replacing starter.

Before and after dyno testing was performed at the same facility...

The higher velocity and cooler intake charge should allow the ECU to advance timing somewhat...fractionally...

The intake charge is hot even before it hits the Airflow sensor....am certain some horsepower could be derived by insulating the plastic ram air section astride radiator and inlet ducting to throttle body... yes it is plastic, but still hot to touch.

Thermal management by extrude honing the cylinder head exhaust ports...polished surfaces means less surface area for heat dissipation into head....possibly allowing stock ECU to further advance ignition before knock sensors trigger pull back.

I believe extrude honing the cylinder head ports coupled with selective application of thermal barriers to cylinder head chamber, valve faces and exhaust ports would yield at least another 20 HP. with increased efficiency while reducing emissions...

So the stock ECU can still unlock potential via ignition system if knock, detonation,,ping, etc is not detected as early in the ignition advance curve by knock sensors. (Anyone with info on the curve?)

Ticker tape mileage reading was steady 31.3 - 31.7 MPG at 65 MPH over flat expressway, no wind with cruise control set and A.C. running...tires at 32 PSI. Actual previous MPG derived miles divided by gallons used has always been higher than display figures. ..will advise...

 

This chart depicts a Ford Mustang 5.0 upper intake manifold. Blue is before extrude hone and Red is after. Notice improvement in uniformity of CFM between runners.
This chart depicts horsepower increase vs reduced intaked air temperature. 30F should be possible by insulating intake charge.

 

Well, hopefully my starter gives up the ghost soon Given 210k miles this is the only car I'd still consider something like this on. Might as well preemptively do the ECU caps as well. I guess my only concern would be the aging trans dealing with the additional torque...especially without the ability to up the line pressure or tweak the shifting programming -- this is a serious gain on a high miles car, not your typical intake/exhaust fluff stuff.

 

And these were sourced from?

 

Looking closer at the dyno graphs I notice your car is running very rich. If there's a way to get the A/F ratio closer to 12.5 - 12.7 there's probably another 10-20hp/tq waiting for you along with better mileage.

 

So I've been scratching my head at the low end power increase. Something about the before dyno is bugging me. I don't want to rain on anyone's parade but...

Take for example the stock 1998 LS400 power specs - 300ft/lbs @4krpm and 290hp @6krpm.

AFTER DYNO: 260tq + 15% drivetrain loss (estimated) is pretty much right on the number - 299 tq.

BEFORE DYNO: Run start after 4krpm but we know it's <190tq. Add 15% and we are still WAY below spec @ <218tq

But why do things come closer to spec after 5krpm? Interesting, because 5krpm is where the VSV valve opens, effectively shortening the intake runners. You can see the transition (short dip) right at 5k on the AFTER dyno. This dip is missing from the BEFORE dyno. Was the VSV valve stuck open (or not able to close completely) on the BEFORE dyno? I don't know if the valve not closing could cause such drastic power loss, but t's conceivable.

Either way, something was definately wrong with your car on the before dyno.