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why does my 350 only have 284 bhp??

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Old Oct 30, 2009 | 01:00 PM
  #1  
jack harrison's Avatar
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From: Bromley south east london, England
Car: 1987 pontiac trans-am
Engine: 350 tpi
Transmission: 700R4
Axle/Gears: 3;73 with eaton lsd
why does my 350 only have 284 bhp??

ok, just got bak from the dyno, mainly to sort my over fueling out. bit peeved off with only 284.2 bhp! its a 350 tpi, with edlebrock aluminum performer heads, cranes cam, 1.6 roller rockers, siameased slp runners and ported plenum ans a 52 mm throttle body and a ram air hood + air box. also heedman headers, de-cat and borla exhust. ive run 13.2 @ 102 mph without the nitrous. is my standard inlet manifold chocking my tpi?
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Old Oct 30, 2009 | 06:18 PM
  #2  
vetteoz's Avatar
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: why does my 350 only have 284 bhp??

Originally Posted by jack harrison
bit peeved off with only 284.2 bhp!
RWHP?
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Old Oct 30, 2009 | 06:25 PM
  #3  
jack harrison's Avatar
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From: Bromley south east london, England
Car: 1987 pontiac trans-am
Engine: 350 tpi
Transmission: 700R4
Axle/Gears: 3;73 with eaton lsd
Re: why does my 350 only have 284 bhp??

no, fly wheel.
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Old Oct 30, 2009 | 07:42 PM
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1MeanZ's Avatar
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From: North Central Indiana
Car: 86 IROC
Engine: 383
Transmission: TKO 600
Axle/Gears: 3.54 Dana 44 IRS
Re: why does my 350 only have 284 bhp??

stock chip?
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Old Oct 30, 2009 | 08:53 PM
  #5  
RED_DRAGON_85's Avatar
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From: Norfolk VA
Car: 85 Camaro IROC
Engine: 5.7 TPI
Transmission: 700-R4
Axle/Gears: open rear, 3.42 gears
Re: why does my 350 only have 284 bhp??

you pulled the engine?
how would you get a flywheel reading?
if thats wheel hp, then thats not too bad and about on track with your mods.
300 wheel hp = 375 crank hp
280 wheel would put you right at around 350 crank, which is 1 hp/ci...

if they put the car on a dyno then did some funny math to give you a reading of flywheel hp, then dont trust it as a number, just a yardstick... meaning that if you go back and have 5 more hp, then you gained.
kinda like standing on a scale that hasnt been calibrated
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Old Oct 31, 2009 | 12:50 AM
  #6  
danziger's Avatar
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From: Chesapeake, VA
Car: 1991 Formula Firebird
Engine: L98 with headers/exhaust
Transmission: 700R4
Axle/Gears: 3.23 10-bolt
Re: why does my 350 only have 284 bhp??

Depending on the weight of your car and the track conditions, 13.2 at 102 could be right in the ball-park for 280rwhp. That's around 350HP through an automatic, which seems quite reasonable considering your mods. I'm not sure where you are getting the BHP numbers, so please elaborate...
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Old Oct 31, 2009 | 01:01 AM
  #7  
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From: San Diego
Car: 1994 Trans Am
Engine: LT1
Transmission: Auto
Axle/Gears: 3.23
Re: why does my 350 only have 284 bhp??

Are you still running the stock torque converter? If so it's not listed in your sig. If not, you should really look into a 3000-3200. That will drop you into the high-mid 12's and should increase your traps by a couple mph. My bro picked up 3mph just by adding a stall in his LT1 car.
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Old Oct 31, 2009 | 05:40 AM
  #8  
jack harrison's Avatar
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From: Bromley south east london, England
Car: 1987 pontiac trans-am
Engine: 350 tpi
Transmission: 700R4
Axle/Gears: 3;73 with eaton lsd
Re: why does my 350 only have 284 bhp??

Originally Posted by 1MeanZ
stock chip?
i had a custom made chip burned. i used to have a 305 but then found a 350 gta junker took the engine out and hade a guy do the heads and cam for me. the custom chip is still in the 305 ecu.
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Old Oct 31, 2009 | 05:44 AM
  #9  
jack harrison's Avatar
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From: Bromley south east london, England
Car: 1987 pontiac trans-am
Engine: 350 tpi
Transmission: 700R4
Axle/Gears: 3;73 with eaton lsd
Re: why does my 350 only have 284 bhp??

Originally Posted by RED_DRAGON_85
you pulled the engine?
how would you get a flywheel reading?
if thats wheel hp, then thats not too bad and about on track with your mods.
300 wheel hp = 375 crank hp
280 wheel would put you right at around 350 crank, which is 1 hp/ci...

if they put the car on a dyno then did some funny math to give you a reading of flywheel hp, then dont trust it as a number, just a yardstick... meaning that if you go back and have 5 more hp, then you gained.
kinda like standing on a scale that hasnt been calibrated
no, i didnt have the engine dyno'd. i was on a rolling road, i think they calculate the rolling resistance of the drive train as the wheels slow down after they've done the run. im not too sure how they work it out to be honest!!
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Old Oct 31, 2009 | 05:57 AM
  #10  
jack harrison's Avatar
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From: Bromley south east london, England
Car: 1987 pontiac trans-am
Engine: 350 tpi
Transmission: 700R4
Axle/Gears: 3;73 with eaton lsd
Re: why does my 350 only have 284 bhp??

Originally Posted by BigWhiteGTP
Are you still running the stock torque converter? If so it's not listed in your sig. If not, you should really look into a 3000-3200. That will drop you into the high-mid 12's and should increase your traps by a couple mph. My bro picked up 3mph just by adding a stall in his LT1 car.
if memory serves me well it has a 2800 torque converter. i had it fitted when i had the 'box rebuilt and the gearing changed.apparantly its the best stall speed for the cam ive got. cant remember what the cam is though!
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Old Oct 31, 2009 | 08:02 AM
  #11  
mreld3r's Avatar
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From: NE Texas
Car: 1986 Iroc, 89RS
Engine: 350 tpi, 350 tbi
Transmission: 700r4,700r4
Axle/Gears: 4.10,2.73
Re: why does my 350 only have 284 bhp??

284 sounds like rear wheel hp, and sounds about right to me.
With your quarter mile times. which by the way are pretty fast for a tpi car.
11's with nitrous and a street car,,,Im impressed, nice ride.
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Old Oct 31, 2009 | 08:15 AM
  #12  
RED_DRAGON_85's Avatar
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Joined: Jun 2008
Posts: 1,298
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From: Norfolk VA
Car: 85 Camaro IROC
Engine: 5.7 TPI
Transmission: 700-R4
Axle/Gears: open rear, 3.42 gears
Re: why does my 350 only have 284 bhp??

Originally Posted by jack harrison
no, i didnt have the engine dyno'd. i was on a rolling road, i think they calculate the rolling resistance of the drive train as the wheels slow down after they've done the run. im not too sure how they work it out to be honest!!
that is the most bogus way to calculate HP ever devised.
the idea is that you get a "true" number but there are so many problems, that again, like i said, dont put faith in the actual numbers, just use them as a yardstick.

go ahead and go to a real dyno, measure your RWHP, do some mods, and measure again.
even a conventional dyno is not going to be completely accurate
most people are disappointed after a dyno run.
just dont get caught up in the numbers. use them as a tuning device instead
heck, multiply by 4 right off the bat and you wont have anything to worry about
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Old Oct 31, 2009 | 09:07 AM
  #13  
Damon's Avatar
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From: Philly, PA
Re: why does my 350 only have 284 bhp??

That all looks pretty good to me. Even with ported this and siamesed that a TPI-style intake is not going to be a high RPM screamer with mind-bending peak HP numbers. It's a good setup for a solid.broad torque curve and it looks like you're getting about what you should be getting, albeit not knowing what cam you've got in it.

Your ETs and MPH tell the real story.
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Old Oct 31, 2009 | 12:31 PM
  #14  
jack harrison's Avatar
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Joined: Nov 2005
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From: Bromley south east london, England
Car: 1987 pontiac trans-am
Engine: 350 tpi
Transmission: 700R4
Axle/Gears: 3;73 with eaton lsd
Re: why does my 350 only have 284 bhp??

thanks for the responses guys. i guess i was just hoping for a bit of bragging rights to tell my buddies! one of my friends wants to get a supercharged honda civic with 300 bhp! i just wanted to show him what REAL power was! tpi's are torque monsters! i reakon id still beat him in the quarter. what do you guys think? and once ive replaced my intake it may help my heads, cam and runners come alive?
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Old Oct 31, 2009 | 12:46 PM
  #15  
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Posts: 683
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From: Florida
Car: '87 Trans-Am
Engine: LB9 (305 TPI)
Transmission: 700R4
Axle/Gears: 3.42 or 3.73..figuring it out still
Re: why does my 350 only have 284 bhp??

Yea, HP numbers on the TPI set-up are going to look unimpressive when 300HP seems to be more "common" in the performance/upgrade world. I have said this before and I'll say it again though, HP sells cars, Torque wins races. You're torque numbers are probably a hell of a lot higher than the 300 HP honda's. However, the weight of the import gives them an edge on us...they don't need as much power per se to get down the track fast...if he's modded enough, he might break into the 13's as well.
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Old Oct 31, 2009 | 05:35 PM
  #16  
vetteoz's Avatar
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: why does my 350 only have 284 bhp??

Originally Posted by Damon
That all looks pretty good to me.
Your ETs and MPH tell the real story.

If you have some spare time your could mod the stock base and save some $$ over buying aftermarket
https://www.thirdgen.org/siameseport
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