Japanimal

What have the Airbox/muffler delete mod done to your torque curves and or tq output? My guess would be that the airbox mod wouldn't affect where torque peaks just the peak numbers. On the other hand, I would think that the muffler deletetion would affect both. I would guess that the tq peak would move higher in the rev range. It may only have a trivial effect, but still I would be interested to know. I guess the removal of 30lbs would negate the effect of a minor tq loss??? With the removal of the spare tire,jack and mufflers that makes my 98 LS about 80lbs lighter in the rear..now how do I lighten up the front end of the LS to balance out the front/rear weight ratio. The only thing I can think of is to switch the stock bat to an optima red top(which I believe is a little lighter.) Any suggestions??

Have you considered wrapping the stock airbox in Design Engineering cooltape to keep the intake charge from absorbing radiant heat from the stock manifolds?

http://www.designengineering.com/products.html
http://www.designengineering.com/cool_tape.html
http://www.performanceunlimited.com/...g/airtemp.html

For every +/- 10 degrees difference in intake air charge there is a corresponding +/- 1% in power output. The effect of the tape would be less on the highway, and in sub 60 degree weather. In these hot Texas summers... it might be worthwhile.

I guess I could use a Raytek to test the temp inside the stock airbox and stock tubing after 30 minutes of driving in various ambient temps, then wrap the stock system all the way to the throttle body and retest to see the changes in temp. What are your thoughts? It would take $50-70 to wrap the whole intake.

Japanimal

After you removed the mufflers did you add a section of stock sized tubing to make up for the removal of the mufflers? Secondly, if you had to describe the sound would you compare it to an AMG Mercedes V8 breathing out of an AMG exhaust or.......not quite? The only Lexus with Exhaust mods I have heard is a 2000 GS400 with a Greddy cat back system.... Sound was Ok, a little too loud for my taste, and at certain Rpm there was droning.

JBrady

Interesting post and questions. The torque/power curve (one in the same)(discussion for another post) is largely dictated by the valve timing. I have not dyno'd my car so I cannot comment on if the curve was effected in any way but if anything has MORE low end than before. I would agree that any improvement in flow effects the higher rpms more due to the restrictions becoming progressively worse as more flow is attempted by either the intake or exhaust.

As far as lightening up the front vs. rear... this would help with handling and weight transfer on hard acceleration. A lightweight battery is an option. Dynobat make a tiny car battery but I can't say whether or not it could support all the power options on a Lexus.

Moving the battery to the trunk is another way to do this. Another option, although not a balance one, is to buy lightweight wheels. This lowers the unsprung weight improving suspension response/handling. It improves acceleration by reducing total vehicle mass and improves power at the road by reducing rotational mass.

Lowering springs will improve handling and aerodynamics.

JBrady

I have also learned to be sceptical of magazine and manufacturers claims. But, given the benefit of a doubt it looks good. Now, the below link shows the different temperatures at various measuring points. I am surprised that there was as great of difference in the factory airbox as they report.

http://www.performanceunlimited.com/...g/airtemp.html

Notice the open air K&N system actually has HIGHER numbers than the under hood temperature. This may be due to it recieving wash flow from the radiator which would be in the 200 degree range :eek:

Notice the coolest temp was measured with a K&N filter in an insulated stock airbox WITH the silencer. I do not know what the configuration of the silencer was but it would look to be a duct from somewhere colder than the box would breath from without it.

Note the power and mileage ratings for some of the configurations tested:

http://www.performanceunlimited.com/...ircleaner.html

Quite an improvement with the colder air, enough to outpower the complete filter box replacement with hot air.

One important consideration. The Ford 460 uses 2 LONG radiator/rubber type tubes to connect the airbox to the engine. Rubber conducts heat better than the plastic in a Lexus and the smaller diameter/longer Ford intake tubes would add more heat than the shorter/larger diameter plastic Lexus intake tube. Therefore insulating the Ford tubes would have a greater impact on air temp as it enters the throttle body vs. the Lexus.

Bottom line... should help. How much? Test, test, test...

Japanimal

The dynabatt wouldnt last long on a daily driver such as ours... with starting duties on top of all the other electrical demands. I really don't have the desire to relocate the battery to the trunk. If there was a way to relocate it to the firewall, that would be a different story. As far as wheels go I have been looking at the SSR GT1's that weigh 15 or so lbs in a 17inch wheel. Not really sure how they would look on an LS400.


If I can get my hands on an air intake cover to modify, I could: install new plugs and a new air filter,have all my fluids flushed, drive 200-300 miles to let the ECM/PCM adjust to the new plugs, then get a baseline dynorun. After that I could remove the headlight seal, install the modded intake cover, remove the rear muffler section...drive another 250-300mi to let the comp adjust and then follow that up with another dynorun to check out the differences. It would be interesting to see what the results are.

I assume the dyno shop would have a fan to simulate cool air.....guess the fan could be adjusted to simulate different speeds 30mph & 60 mph respectively. Would this help simulate the effect of the intake mod at different speeds in the real world?

JBrady

While I have not had my LS on a dyno I have made MANY runs at the track. I did multiple runs with and without the modified airbox and picked up a calculated 7hp (engine) granted this was not completely scientific, but consistent and real world. This did NOT allow the ECU to adjust so there could be more power... or less... I cannot say. Although the last time out I pulled the ECU fuses after the first run and ran quicker the next 2 passes

As far as the mufflers go, I did plan on running with and without them but ended up just running without. The 1st visit to the track without netted better times by one tenth even though the air conditions were worse than the previous time. I even had the mufflers in the trunk so there was no weight benefit either total or in ratio front to rear.

The last time had similar air but I unloaded the trunk including spare and jack.

I am planning on going tonight with substancially better air. We shall see if I can get 14.5s out of this LS400 and make a bunch of GS owners jealous (more than already)

As far as the air box cover, I called the Lexus autobody shop and lucked out as there was a 95 LS400 getting front end repair. Its box cover had cracked the front support and was being replaced. This looks to be common. The replacement is expensive but they throw away the old parts. The manager gave it to me free. I gave him a 12 pack of beer as thanks. (you never know when this type of goodwill will come in handy) I suggest making a couple calls, maybe a pre-donated 12 pack could put you on the waiting "list" for the next 95-2000 LS400 front repair job

Japanimal

Another thing to consider is heat output of a Lexus 4L v8 In a slightly more cramped engine compartment vs an Big Block Ford in a large engine compartment. My guess is that radiant heat would be fairly similar. I do agree that the lexus intake ...by nature of it's routing, materials, and the fact that the stock Lexus manifolds have some decent heat shielding from the factory would have less of problem with radiant heat. I guess the only way to find out is to buy a raytek and compare ambient vs underhood vs temps inside the intake tubing.

I am also VERY skeptical of magazine articles as well. I would love to believe they are all credible all the time...but alas I have to take into account that magazine's survive off of advertising dollars, and take everything I read with a grain of salt. I have used the design engineering cool tape 3 times on stock airboxes. I didn't do any temp testing but the owners of the other two vehicles shared my experience that while not noticing an outright seat of pants gain...there was definetly a increase in the consistency of performance. Have you ever noticed the difference between the way your vehicle runs on a hot 95 degree day and how it runs a lot better that same night when the ambient has come down about 10 to 15 degrees. We all noticed that the ambient temp fluctuations seems to affect our performance drastically less. The three vehicles were a 99 Tahoe Sport (2dr) with 40k and no other mods. A 97 Jeep Wrangler TJ with Headers and a catback exhaust, A 99 Tahoe 4 dr with a catback exhaust and 6k on it.

You up for temp testing JBrady?

JBrady

Japanimal, we seem to be in agreement on all counts.

I am always interested in testing. Temp testing needs some sort of test probes. What did you have in mind?

Japanimal

http://www.raytek.com/

I think you can pick one up for about $75 or so.

Japanimal

http://www.handsontools.com/store/sh...roduct_id=1322


MSRP is $100 for the Raytek with a laser site....above site has for $75

This site:
http://www.independentracing.com/Co/Raytek.html

has em for $69

http://www.napaonline.com/cgi-bin/nc...2&prmenbr=5806

has them for $100