TexasLex

Thanks for the offer to help and for the compliment. The dyno chart is hard to read b/c I had to compress the file to get it to load to the post. I sent an email to the mechanic asking him to email the dyno run to me, if and when he does I will forward it on to you.

I don't know which gear they hit, the car was hitting the rev limiter before going to second when I got it back, so I am wondering if that may have hurt the #'s. Anyway, it turns out they used Toyota ATF instead of Toyota Type IV fluid so I called the dealer and they said that would affect the shifting and cause excess heat. So, now I need to have the trans flushed.


Actually, from the header outlet flanges to the cats is 2.5". I had them do it that way to try to get more of tapering off from the 2.5" to the 2.25".

Thanks again

TexasLex

I had the tranny flushed and refilled today with Type IV and the car seems to be running much better. Seems faster and does not hit the rev limiter hard, if at all. Plan to have it re-dyno'd when I take it in for the muffler swap this Wednesday.

GILLEXUS

iTrader: (14)

SC & RX,
What size is your X-pipe 2.25" or 2.5" If it is 2.5"that might be an issue. Maybe check w/ the exhaust guru JBrady if running 2.5"vs. 2.25" pipe from the header to after the X-pipe helps or hurt the power band. I would gues that it would help. Just my $.02

When you re- dyno check and see what gesr he mostly uses I don't know what the final drive gear ratios are for your car but I know for the GS 400/430 4th gear is the closet to 1:1 gear rario. It is best to dyno in as close to 1:1 rario if possible. A different gear is OK just might be a few HP's lower.
Some times for my car it was hard for the dyno guy to keep it in 4th and rev the engine hard w/o it wanting to down shift into 3rd. So he just did it in 3rd. because it was easier.

TexasLex

I went back to the shop yesterday to drop off the car to have the mufflers switched and planned to ask about the dyno data while I was there. It turns out the dyno guy had already started his vacation so could not get any additional info.

Regarding the resonance issue, you are correct, I should ask Jbrady (should have asked him before I spent the fist load of $). Now the shop wants $900 to switch the mufflers. I told them "no thanks" and that I would come pick up the car tomorrow. I read on a forum for a different car maker's product that adding exhaust hangers up near the front of the system would help quite the droning. This makes sense so I am going to try this first. I also noticed a pic where someone had a cross brace welded in between the two pipes near where the engine and transmission join together. Does anyone know if this would help?

Also, when standing outside the car the resonance seems the loudest in the middle, could it be that having the resonators welded together is causing this terrible resonance? Or perhaps you are right and it is the "X" pipe. Hate to have to switch to a "Y" pipe setup at this point because I don't want to keep throwing money at it.

GILLEXUS

iTrader: (14)

That sucks that they want $900 to replace the muffllers is there another shop in town that might do it for less? I'm bugged also as to what can be causing the load resonance. Maybe just need largersize muffler maybe the Magaflow mufller that a few of the GS guys were getting..

JBrady

There are SEVERAL parts to exhaust system "tuning". One would be for maximum performance and subgroup to that would be targeting peak numbers or targeting widest power band. Related but different is SOUND tuning. Just like a trombone changes tone as you adjust the pipe length so does ANY and EVERY change to the exhaust system effect its sound charactaristics. As you noted more than one person thinks your system sounds perfect but you are not happy with the sports car note so individual preference is also an issue.

The standard Lexus exhaust design is of course for maximum quietness. Changing to create more power makes keeping "Lexus" quiet much harder. Systems need to be engineered AND tested. My advice has always been to mimic the stock system and use the SMALLEST pipe size that will support the power goal. Small pipe size must be supported with quality and efficient transitions. A transision is a turn, a change in diameter, a change in shape, an X Y or H pipe, catalyst(s), resonators, mufflers all the way to the tailpipe size and location.

People want quick, simple, cheap answers to what should they use. Generally the question is what pipe size and X or Y pipe. Once somebody has invested in a full exhaust such as this it is VERY hard economically to make substantial changes.

That said, and with the UNDERSTANDING that any recommendation I make is a best guess with ALL the above variables. I would use 2.00, 2.125 or 2.25" pipe sizes, mandrel bent throughout. I would make ALL transitions as internally smooth as possible. I would place the X or Y pipe as close to the engine as possible. My preference is dual Y pipes with a resonator between them just like factory design but with my nozzle collector design. I would place the second set of resonators in the same location as the factory. Using PROPERLY insulated hangers in the factory locations is also highly recommended.

Welding support crosses at locations between dual sections will stiffen the system and change its harmonics. How much depends on many things and it may make some sense to try clamping the support in place prior to welding to determine if the result is desireable. This is called R&D. Some actually enjoy trying different configurations and observing the results. Some or shall I say most would prefer a bolt on system that is "perfect" and inexpensive. Price a NEW stock system from Lexus for a pricing reality check.

None of the above is meant as a rant or lack of patience. Rather I am trying to help educate the people trying their best to improve their cars personal appeal. My hat is off to everyone making this effort.

TexasLex

I will assume that your reply was not directed at me specifically when you wrote that "everyone" wants something that is perfect AND inexpensive. I also feel that there is way too much of that type of talk out there, these are Lexus automobiles after all! If someone wanted cheap and perfect they should go with a Chevy 350 application in which case they would have to choose between many different already tried and proven exhaust systems. However, I believe the fact that I have already invested in a 2.25", mandrel bent, TIG welded system with an "X" pipe is proof enough that I am not trying to go the cheap route. (I went with the 2.25" b/c I do intend to add a whipple-type supercharger if one comes on to the market for US vehicles.)

I do appreciate your advice regarding trail fitting the cross-brace and of using properly insulated hangers in the stock locations. I have decided to try those ideas first, and then gauge how the system sounds. If it is then determined that the mufflers are the main remaining source of resonance, I will switch them out. If it seems like it is a combination of the mufflers, system routing and need for more resonators causing the resonance, I plan to add another set of resonators in the factory location in addition to switching the mufflers.

trbopooh

Hi Jbrady,

I was over at lextreme.com and was wondering if there was anything that you were holding out on us?

Mike

JBrady

Do you mean the nozzle collector for the Y pipe? I mentioned it in my post above. For those that aren't following that closely I have developed a torque enhancing Y pipe I call a nozzle collector. Standard racing merge collectors are designed to minimize the collector volume to improve velocity through the collector. Even so they still have a larger volume at the collector than the pipe from the collector. This means the flow will slow in the collector and then speed back up again as it enters the Y. This creates a loss of velocity and the potential for reversion of pressure at the wrong time.

My nozzle collector speeds the gas flow up slightly before the collector and reduces the collector volume even more relative to the standard racing collector. This creates more not less velocity through the collector and reduces the chance of reversion and increases scavenging.

I have shipped a couple sets of Y pipes and am waiting on the results but things look very good. One set is dual 2.00"s into a single 2.50" and the other is 2.25s into 2.50.

If anyone is in the Rochester NY area with a GS4xx and wants to look at doing a full Y pipe from the cats back send me a PM. If anyone has their GS off the road for the winter and would consider shipping me their Y pipe PM me.

Looks like a conventional racing merge collector from the outside but the magic is inside

trbopooh

I am interested...Would you like to pm me with details? Price? ETA?

Thanks,

Mike

Pearlpower

iTrader: (2)

For some feedback on my SC430 header installation, see here. I would imagine the same for GS430 cars.

https://www.clublexus.com/forums/sho...8&page=1&pp=40

Pearlpower

iTrader: (2)

Dyno results for headers are in. See link
https://www.clublexus.com/forums/sho...8&page=2&pp=40

Kharizma

iTrader: (6)

ME TOO

Kharizma

iTrader: (6)

anything?!?!