intake/headers/exhaust/safc and cams should get you 300rwhp. not sure if safc allows you to advance timing but that's something you can do with vvti.

 

I also said port and polish, these would also be 'quality' items i guess. a rough estimate sheesh.

what like 300 for the 'almighty' k&n intake, 800 or so for headers, 1k for an exhaust, 200 for an afc, that's 2300 right there. LABOR on putting those in will be a grip alone. Tuning the afc would be 150 an hour at least from a reputable tuning shop, and you need to dynograph it.

Port maching and polishing the intake manifold, and both sides of the heads on a Honda will cost about 1k, it's probably double for the GS4xx, AND you have to think about the labor for doing that, what's involved in getting the heads out and intake mani out and putting it all back in. Since you were already tearing it apart, switch those head gaskets out, might as well change cams (if you can even find them) or get them reground to match the PnP, that add more money to the pot.

It could easily become a much more involved money pit, where there are other options, in the same price range, that would be better effective in the power/cost dept.

How much does a custom turbo setup run? even at like 7psi it would push out more HP and be very reliable.

JPI had a supercharger setup that was pretty much built to however powerful you wanted it to be, from basic bolt on, to fully rebuilt internals, fuel system, and supercharger.

In the end, it's this guy's money, and he'll do what he wants.

 

Thanks for all your help guys. I'm thoroughly up in the air now. I'm not in a rush to get the car, I just want a plan because every car I've ever owned ended up being the model I didn't want (Eclipse Spyder w/ 2.4L N/A, Audi A4 w/ 2.8L 6 cyl, etc.). From now on, I'm researching. Your input does help a lot.

The V8 looks great, and FI on it is a dream... But, the I6 can be cheaper at purchase, on insurance, on gas...and inexpensive turbo kits are readily available--some producing over 400rwhp. But...it's not a V8, and it can be less reliable.

 

What's isn't reliable is the transmission. It can't handle over (this is debated) 400-450 hp. Not without upgrades. Search for user 'JeffTsai'. That dude went turbo crazy on his gs300. VERY appealing if you ask me...heheh.

In the end, get what you like.

 

With the GS it seems like there really isnt a ****ty model like what you are trying to avoid. The 300 has the 2jz and the 4** have a nice v8.

 

OK--my research/options have narrowed to:

What's faster from 0-60mph or 1/4 mile:

An XSPower T61 turbo setup on a GS300 (assuming ~400whp)

or

A GS400 with an exhaust/header, intake, tuned SAFC, and 100 shot of NO2? (assuming ~380whp)

 

There's no real way to say unless you line them up. The turbo is going to take a little while to spool. The nitroused GS400 will probably take it to 60. In the 1/4 the GS300 would probably edge it out. Now if you put a little shot of nitrous say a 50 between 3-4500 rpms to the GS300 that could be a special machine.

 

My car would probably run mid to high 12s to give you a comparison. But I beat about anything off the line up to 60.

 

I am still waiting to see someone successfully run larger camshafts of the 1998-2006 Lexus VVTi engines. IMO the VVTi is not really a performance solution as much as it is emissions. The system simply changes the phasing between the intake and exhaust camshafts and that increases or decreases overlap. Lexus actually increases overlap to create exhaust gas recirculation (EGR) and that is why these engines do not have and external EGR valve.

The problem is increasing the duration used will result in even more overlap during that phasing and later and earlier events depending on the VVTi event programming. The solution may be higher lift with similar duration. This would also require the heads to be PROPERLY ported (no easy feat) to take advantage of the higher lift as some testing shows the stock ports loosing flow at higher lifts.

Some very interesting testing has been done on the non-VVTi engines with surprisingly strong power at higher RPM with STOCK cams and heads
Stock for these engines is around 230hp so this graph represents a 75hp gain from ITBs, full racing headers, dry sump oiling, full tuning for around 305hp.




With full modifications the engine recorded 534hp at 8400rpm.



This is NOT an engine you want in your street driven Lexus as MUCH as you THINK it would be...



Here is the car this engine was created for.

 

Sorry, got off track...

Point being I have not seen a 300rwhp dyno from these cars. If you look at the RPM of the above graphs you see the power being made above 6000rpm. Stock rev limit is 6250rpm so to get some real power the best bet is to get around the stock rev limiter. Sounds simple but again, I haven't seen anyone that has done it.

Standard available parts on stock cams/heads would probably break 300rwhp at 7000rpm.

 

Raising compression increases power, no doubt about it. How much? Not sure. Thats what all the big cube american muscle cars do. Some run as high as 14.5:1 CR and maybe more. Stock GS is 10:1 I think. I wouldn't see anything wrong with running maybe a couple points higher as long as you had proper piston to valve clearance of at least .025". These cars do have a knock detector and will retard the timing to help prevent detonation, but your probably going to have to run octane boost or EEK!! racing gas.