Jbrady

Just have my headers installed. Here are the dyno sheets, before and after. Thank you for putting this whole header thing together.

 

Great numbers. I just posted comments on the dyno #s in your thread.

https://www.clublexus.com/forums/sho...62#post1551962

 

Slight change in plans plus additional good news.

Way back in January of 2004 CL member VVT-i posted the part numbers for the manifolds for the 6 VVT-i equipped vehicles in question those being: 98-00 GS400, 01+ GS430, 98-00 SC400, 01+ SC430 and the 98-00 LS400, 01+ LS430. We planned for needing to relocate cats and build an aftermarket Y pipe for any pre-98 vehicle. We HOPED that one manifold would fit all the 98+ vehicles.

With the help of member VVT-i we learned that there were 4 different part number groups for the 6 vehicles above. All the 430 vehicles had the same part number. Each of the 400 vehicles had a different part number. Since I had personally seen the LS400 manifolds and the GS400 manifolds and they LOOKED identical, and, since the SC400 was rated the same power as the LS400 it seems resonable to assume that all 3 models had the same manifold with maybe minor differences.

I next looked at an LS430 and realized it had a completely different style manifold. This lead me to presume that the planned header would bolt on but that an aftermarket custom Y pipe would probably be required.

Turns out I was WRONG about both above paragraph assumptions.

Member jp430 recently installed his headers on his supercharged GS430 and everything bolted up perfectly including the stock Y pipe. This should reasonably indicated that ALL 430 vehicles that share the same part number on the manifolds can install these headers as a direct bolt in with no other mods needed. Two very nice benefits being that the new design stock 430 manifold is more restrictive but smaller in size. This means that the power increase should be better than for the 400 applications and the install easier as well. jp430 reports a reasonably quick install time.

Now, some may have noticed my post way back regarding trying a GS400 Y pipe on my LS400 and it did not fit. It looked nearly identical but the flange angles were off just enough to make it not work. This was my first indication that there was in fact a difference on the 400 cars. I hoped it was a change in the catalyst but did not know for certain.

Just this monday CL member SRQ400 had his headers installed on his 99 SC400. Turns out the SC400 has a very restrictive single tube manifold that gives the same benefit of the 430s above. However it does not work with the stock Y pipe. BTW, SRQ400 (Greg) was the person that pointed me towards S&S Headers in the first place so my hat is off to him. Greg had dual 2.25" installed with his stock mufflers and is AMAZED at the performance improvement of both POWER and RESPONSE.

This promted me to scruitinize the GS vs LS manifolds again. As I said they LOOKED identical. Upon very critical observation I see that the catalyst 3 bolt flange is rotated 270 degrees. Obviously these are not identical. This indicates that LS400s will also need different Y pipes as the stock parts will not work. This is just as well because the stock Y pipe is very restrictive.

 

Check it out...
https://www.clublexus.com/forums/sho...d.php?t=186633

 

sounds like good news for 430 owners I'm dying for dyno numbers on a stock GS430

 

I'm on this when ever it's avalible.

 

Over 30 sets have already been built.

Call S&S Headers to order of via web at www.ssheaders.com

 

Can you tell me how much install for the headers would be for GS430?

 

That will of course vary from shop to shop. Luckily (for header upgrades) the 430 engines have more compact stock manifolds than the 400 engines. Why is this important? The hardest part of the install on a GS400 is simply removing the stock manifolds. This is MUCH easier on a 430 engine. I believe 4-5 hours is a fair install time. Shop rates run $50-$75 per hour so a fair estimate on the price range is $200-$375 although some may find it cheaper and others could pay more.

 

Jbrady after install should i get it tuned or will the computer ecu learn itself, and if i need to have it tuned what do i need or the shop should do all that.

 

Here is JBrady's chart of JP430-Header-S/C' dyno -Re-done

 

Is the car leaning out and the ecu retarding timing around 118-120mph? -56-58 hp? I think this was done before final tuning was done right?

 

NOPE... the problem is there is no data for the headers and the last 2 speed ranges. What is calculated is actually the stock manfold TQ minus the stock manifold HP. From the curve and if there was no dyno glitch the spread would probably be 5-15rwhp greater than the spread at 117mph. Probably more like 345rwhp vs 305rwhp.

GILLEXUS, please delete the last 2 data points, 118mph and 120mph, to avoid this possible confusion. I will do the same in the other thread. Thanks.

 

Gotcha. Thanks for the clarification.

 

Jbrady, last data line deleted on dyno chart.

It would be really nice to see a dyno with rpm readings. My headers should be coming soon been over 2 months.

Looks like form the only people that have posted any installs info.JP430,trbopooh and SRQ400. that the headers are a direct bolt-on for GS400,GS430 but SC400 need fabing of Y -pipe.
I think trbotpooh has the gs400??