First off, you're talking total HP output of 235-245 (which is roughly 190-200 whp).

I can tell you for a FACT that this will not happen, period. Remember how I've said that advertised HP gains are a load of crap? The bad thing is, they manipulate numbers to make themselves look good- they take dyno numbers from areas on the graph other than the peak, and so on.

Take a look here:

http://www.clubgp.com/newforum/tm.as...mode=1&smode=1

You're predicting your setup will make more power than people with a cam and headers- there is definitely no way. You can also see the record for a stock cam 3800 is 187 WHP- so I wouldn't personally expect to beat this unless you buy every bolt on possible and get a custom PCM tune (I don't know what mods Stuffy had, but if the record was so easy to break with bolt ons, it probably would've been done by now).

This would tell me that if you gained 10-15 crank horsepower from all those mods you want to do, that you'd be about right. 210-215 crank hp = 168-172 whp, so that would put you just under the NA stock cam records- I'd say thats about right.


IMO a turbo would be a bit easier to install; as would ZZP's SS M90 kit. A top swap would be a bit more difficult though.

Thats going to be very tough to do- even the L67's in stock form have a hard time keeping up with modern V6's.

The new revisions are fine- the older ones had problems with cracking. Really, if he wants to stick NA, he has no other choice. The stock front manifold is garbage, making a ported front pretty useless; and if he's stuck on NA, headers are out unless he can find some S&S's.

This doesn't have to be the case, you could call around to the various PCM tune places and see if they sell a version optimized for 87- its just a matter of not cranking the timing up so much. You obviously won't get nearly the gains though.

Require tuning- no; but a tune is extremely beneficial- even on 87 octane and no raised shift points- getting the fueling maps smoothed out and set up specifically for your engine (ie custom tune) help quite a bit. Even stock cars benefit from tuning- the more mods you add, the further you get away from the factory tune being "ok". Not to mention, there is a lot you can do in torque management and such.

If that is your main setback, then thats simple to fix. Use a stock airbox with a K&N panel filter. Sure, you're gonna lose some power (try getting a airbox from a factory SC car like a SC SS monte or GTP) over a CAI/FWI- but it will be dead silent. From the factory, the SC GTPs and montes and such have 0 whine.

The bad thing is, you're into the money of the 'big fish', you've got like a $2000 mod list, and you're only going to be marginally faster than stock, and still getting killed by stock L67 cars.

Looking at that HP chart above if you're dead set on NA, no bottle, no boost- you're gonna need a cam- no questions. But then that defeats this:

and your thing against getting a tuned PCM.

What allows this to work is the fact that you have 2 timing tables- "good fuel" and "bad fuel". The computer runs the good fuel table until you have knock, and then backs down steps until it gets to the bad fuel table (if you have tons of knock)- which is as little timing as it can run. No tuned pcm I know of touches the bad fuel table- so you always can fall back to that. This is totally different on the L67- because knock leads you to chipped pistons real quick, but I've never seen an NA L36 chip pistons from knock- you just won't get all the power you could if you ran premium. This is how the newer GTP's with the L32s, and other new GM performance cars work with their "premium reccomended" instead of required.

If you're worried about life of the vehicle- don't do any performance mods, and don't floor the car. Baby the thing around for the rest of its life. I've seen stock L67's go 200k+ miles just as much as stock L36's, it just depends how much you beat on it- and if you're doing performance mods, you're probably beating on it more than the normal person.

More pressure and quicker shifts, definitely. Best reliability is stock- tons of torque management to cut power during shifts, and ease through shifts slowly on the clutches.

IMO, huge waste of money. ~$1000 for virtually no performance gains...



Just trying to give my opinions on the above stuff- I'd say if you want to go that far, pick up a cheapy used turbo kit, or do a top swap.

 

I agree completely.

 

with the mods you wanted to go with, i think bumpin said it perfectly. he's like a scientist with 3800's.

as far as cat backs, if your not doing any modding and just want the sound, just replace the mufflers. i got my catback for 550 off gmpartsdirect.com i did it just because i wanted to change the piping and get a better sound to the car. performance wise, it brings hardly anything to the table. if your buying it for performance, dont. because you wont get it. sorry to burst your bubble

 

Wow, Bumpin is pretty much a scientist, you summed it up pretty well...and yeah, if I'm looking to spend over $2,000 on this car then I might as well go all the way and S/C it, far more gains there. Last question on this thread, if I S/C the car and get an additional 30-50HP, whatever the MS90 kit will give with no other bolt ons, will my transmission be fine? I know in 2004 they upgraded the tranny to a Heavy Duty version, more capable to take on more power and torque. And when it comes to my driving style I'd say that 75% of the time I drive it normally, the other 25% I may race it.

 

Definitely no garauntees your transmission will be fine- even at the stock level, people occasionally pop them. There are a few things that will help save it:

-Don't do the down skipshifts (ie 4-2) w/ the aftermarket pcms anymore than you have to
-Be very careful during burnouts that both wheels are spinning roughly the same speed, if you get one wheel spinning significantly faster than the other, you're gonna cook the diff
-Leave the torque management on for reducing power between shifts (although with the more power you make, the more sense it makes to quicken the shifts because with more power- you're putting a lot more stress riding the clutches)
-Don't use DR's or slicks at the track- hard dead hook launches are tough on the hard parts in the tranny.

This goes for your stock transmission, or the stock "HD" transmission- doesn't make a difference. Never discount the possibility that your transmission could blow- especially when you race it. I've heard one guy run a stock 4t65 on a ~500whp turbo gxp with no problems, and I've heard people with stock L36's and stock L67's break transmissions; so just keep in mind, there are never garauntees when it comes to our transmissions.


Onto the 4t65e vs 4t65e HD debate- there is really very little different between your transmission and a 4t65HD (they have been offered since the late 90s in grand prixs). You have a smaller torque converter (the HD guys "upgrade" to the smaller size when they buy aftermarket torque converters with higher stalls); other than that- the only internal differences have to do with the gear ratios (you have a 3.29, they have a 2.93- both of the same strength; so yours is actually better for 1/4 mile racing); the other main difference is the differential. The HD transmission has a bigger diff, bigger diff housing, and shortened passenger axle to accomodate the different housing. You can easily upgrade your transmission to the "HD" diff without removing it from the passenger wheel well (look on ZZP in the trans section for the HD upgrade- although its cheaper to buy a blown 4t65HD, or the parts alone off clubgp).

Really, its debatable whether its worth taking the time and money to do that- when most 4t65's fail, its usually not at the differential unless the person was doing big 1 wheel burnouts (and then, even the HD differential wouldn't save you).

 

Wow, thanks. Seems like you know everything there is to know about engines and transmissions and all the mechanics between them. I suppose the best bet would be to upgrade to Dexron VI, change the fluid every 30,000-50,000 miles, change the filter at the same time, and don't race often. I really didn't know the two trannies had so much in common, but thank you for all the information.

 

I have the same magnaflow too and love it, you can usually get a used one on ebay or cragislist. I wanted a valid warranty so I got it here. Magnaflow 15930. Also some of the forum sponsors usually have a sale going on. Either way its a great exhaust system, sounds great, and very easy to install.