what do I need to get to 400 hp.

[Street Fighter]

I have a 99 trans Am with 43,000 miles on it stock accept for ws6 air box and K&N air filter. plan on spending some money on it after 15 years of going stock, I feel that 400hp will be a nice 16th birthday gift. What do I need to have done to reach this number. Not buying a engine want to keep my low mileage engine. what places do any of you know of that take on a job like this and do great work not just good.

[98TransAmWs-6]

Well depending on your budget depends on how you get there. You can easily get well over 400 if you have the money. The cheapest route would be to get airbox lid, headers with a y-pipe and catback, cam, and ls6 (243 heads). You may be able to get away with out heads but I would suggest it especially if going with a big cam. I would suggest upgrading the suspension at some point as well as once you get higher in the power levels you will not be able to put that power to the ground adequately.

Also there are supporting upgrades I would do as well in order to prevent things from breaking from the additional power like a better timing chain and oil pump, upgraded valvesprings, chromoly pushrods, etc.

[35th-ANV-SS]

If you're looking for 400rwhp, you'll need about 480hp at the crank. That's assuming a 17% drive train loss. If you want 400hp at the crank, that's only 50-60 more than you have now, or about 40 more rwhp. Big difference between the two. Which are you aiming for?

[Street Fighter]

want 400 at the crank. I noticed that you said that it would only be a 50 or 60hp bump in performance. what is the horsepower rating on this cars, like I said all I have done is a ws6 airbox a lid a k&n air filter and a ws6 hood.

[35th-ANV-SS]

Well, the 99 has a little less than the 2001/2002 models since they have the LS6 intake. I didn't take that into consideration. I would guess about 320ish. LS1 later models are rated at 325, but in all honestly they are closer to 350. With that said, I would say that the LS6 intake, headers, and a full exhaust would put you at high 300's. Throw a cam in there and you'll easily be over 400. Try not to get too hyped about hitting an exact HP level though. The most important thing is that the car runs solid.

[dabest09]

Full bolt ons should get you really close to that goal.

[99ss405]

headers cam converter tune

- - - Updated - - -

Well, the 99 has a little less than the 2001/2002 models since they have the LS6 intake. I didn't take that into consideration. I would guess about 320ish. LS1 later models are rated at 325, but in all honestly they are closer to 350. With that said, I would say that the LS6 intake, headers, and a full exhaust would put you at high 300's. Throw a cam in there and you'll easily be over 400. Try not to get too hyped about hitting an exact HP level though. The most important thing is that the car runs solid.

truth !!!

[Alwyn the Wolf]

Well since you have your intake upgraded already... I'd go with LT headers, SLP loudmouth 1 or 2 catback, Underdrive pulleys (those are cheep and it will give about 10hp), Cam, and some STICKY tires... that will definitely get the job done.

[Naaman]

Well, the 99 has a little less than the 2001/2002 models since they have the LS6 intake. I didn't take that into consideration. I would guess about 320ish. LS1 later models are rated at 325, but in all honestly they are closer to 350. With that said, I would say that the LS6 intake, headers, and a full exhaust would put you at high 300's. Throw a cam in there and you'll easily be over 400. Try not to get too hyped about hitting an exact HP level though. The most important thing is that the car runs solid.

For what its worth, my 98 came with a dyno from the previous owner when I bought it. 275 rwhp, 296 rwtq. I figure that puts it at around 320 - 325 at the crank. It had an air lid, K&N and a cat-back on it. Other than that, should be the same as the 99, I think, though the factory always rated the birds a few horsepower higher than the Camaros...

[SMWS6TA]

was that on a Mustang dyno or a very stingy dyno? That's quite low.

[Whamhammer]

For what its worth, my 98 came with a dyno from the previous owner when I bought it. 275 rwhp, 296 rwtq. I figure that puts it at around 320 - 325 at the crank. It had an air lid, K&N and a cat-back on it. Other than that, should be the same as the 99, I think, though the factory always rated the birds a few horsepower higher than the Camaros...

I agree with SMWS6TA, that output sounds lowe compared to what Ive heard from every other dyno ( usually 290-300 rwhp).

As far as "'birds being rated a few horsepower higher than the Camaro" from the factory, where have you seen that? I havent seen a deviation between the two since late 80's 305 TPI automatics, mostly from the way the air was ducted. Between the two.

[35th-ANV-SS]

Every dyno is different. Hell, even the same dyno on the same day on the same car produces different results. Lots of variables involved. Air, dyno setup, humidity, temperature, elevation, tune, the dyno itself, how well was the motor running, cold run, hot run, hood open, hood closed, tire position on rollers, gear selection, rear end gearing, tire pressure, mass of the rear wheels, fuel octane, etc etc etc.

Wouldn't get too caught up on numbers.

[SMWS6TA]

Jon I agree with what you said just that those numbers are quite a bit different then what I've normally seen with stock cars, Hell mine was with similar setup, A 98 with stock heads, dyno with a LS6 intake and LT's on a 85* day around 340ish with a Frost tune.

[35th-ANV-SS]

I agree they look a little low, but could have been a Mustang Dyno on a stock tune with a number of those variables hindering it some. Hard to tell when he wasn't there to witness it. A Frost tune and headers offer huge HP/TQ gains.

[Naaman]

I don't know the details or even whether the couple of bolt-ons were installed when the dyno was run. All I know for sure is that it was done somewhere in Washington state. Altitude was probably a little bit high, but I don't know (I'm basing this off of how fast I can run in WA vs some of the lower altitudes in southern states, such as NC or MO... I was always slower in WA).

In any case, that same set up with only a ported throttle body added to it was able to hang with an LS2 Corvette from about 25 to 105 before the Corvette started to pull away (and only very slightly)... though that could also be attributed to the driver mod.

[Naaman]

I agree with SMWS6TA, that output sounds lowe compared to what Ive heard from every other dyno ( usually 290-300 rwhp).

As far as "'birds being rated a few horsepower higher than the Camaro" from the factory, where have you seen that? I havent seen a deviation between the two since late 80's 305 TPI automatics, mostly from the way the air was ducted. Between the two.

I seem to remember the SS being rated for 325 or 335 horsepower and the WS6 being rated for 345... the wayback machine might be able to confirm this...

2002 WS6 rated for 325 HP/350 ft.lbs http://web.archive.org/web/200212131...ransam_coupe#1

2002 SS rated for 325 HP/350 ft.lbs http://web.archive.org/web/200304131...am_catalog.pdf

Maybe it was the Firehawk... :/

[SMWS6TA]

That might be the culprit right there. Altitude.

[35th-ANV-SS]

I believe 325HP was the rating for the standard WS6 and SS package. Cars which came equipped with the SLP lid/cat back were said to have been rated at 345HP.

[Naaman]

I believe 325HP was the rating for the standard WS6 and SS package. Cars which came equipped with the SLP lid/cat back were said to have been rated at 345HP.

Yeah, okay... that's what I thought.

[theorangeguy]

I watched a trex cam with stock heads, true duals, long tubes, and an m6 put down just shy of 415rwhp. 2002 SS.