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300hp 305

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Old Aug 20, 2003 | 11:51 AM
  #1  
Damien00677's Avatar
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From: Dubuque, IA
Car: 2006 'Nox 91 Camaro RS 91 1500 Silv
Engine: GM 3.8L, 305 SBC, 350 SBC
Transmission: Auto, auto, auto
300hp 305

How practical is it to make 300 hp out of a TBI 305, and how much cash would it take?
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Old Aug 20, 2003 | 12:21 PM
  #2  
iroc22's Avatar
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From: Surrey, BC
It's going to take a lot of work. There's no one on this site that has a 300hp 305 TBI.
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Old Aug 20, 2003 | 04:15 PM
  #3  
89RsPower!'s Avatar
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From: New Jersey
Car: 86 Corvette, 89 IROC, 1999 TA
Engine: 350, 350, LS1
Transmission: 700r4, 700r4, T-56
Axle/Gears: 3.07, 373, 4.10
umm more cash then it would take 2 build a 300 hp 350 with a carb n replace the 305.
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Old Aug 20, 2003 | 05:12 PM
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Sitting Bull's Avatar
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From: Calgary, Alberta, Republic of Western Canada
Car: 1986 Sport Coupé
Engine: 305-4v
Transmission: 700R4 and TransGo2
If your shortblock is in good shape, you can switch to a carb and hit 300 hp fairly easily. It will require all the stuff in my sig to do it but my car now satisfies my need for speed and gets 19.5 mpg around town too

All these parts will work perfectly well on a 350, too, once you wear out the 305.
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Old Aug 20, 2003 | 07:20 PM
  #5  
iroc22's Avatar
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From: Surrey, BC
Originally posted by Sitting Bull
If your shortblock is in good shape, you can switch to a carb and hit 300 hp fairly easily. It will require all the stuff in my sig to do it
Have you taken it to the track?
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Old Aug 20, 2003 | 08:17 PM
  #6  
Sitting Bull's Avatar
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From: Calgary, Alberta, Republic of Western Canada
Car: 1986 Sport Coupé
Engine: 305-4v
Transmission: 700R4 and TransGo2
Originally posted by iroc22
Have you taken it to the track?
No I haven't.
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Old Aug 20, 2003 | 08:40 PM
  #7  
TunedPort 335's Avatar
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From: Paxton, MA
Car: 1987 Camaro Z28
Engine: 335 TPI Stroker
Transmission: Tremec TKO 500
Axle/Gears: 10 bolt / 3.42
Have you dynoed it ?
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Old Aug 20, 2003 | 08:49 PM
  #8  
92ChargedRS's Avatar
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From: Marshall, MI
I've been debating the same idea. Build mine or build a 350? The only reason i don't want to build the 305 is i'm worried about the miles on the stock bottom end with new parts. Mostly because of higher compression.
Here are a couple of links to build ups on 305's.

http://www.goingfaster.com/spo/carcraft325hp305.html

http://www.chevyhiperformance.com/projectbuild/48158/
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Old Aug 20, 2003 | 09:04 PM
  #9  
zippy's Avatar
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From: Chander, Arizona USA
Car: 2006 Silverado 1500
Engine: 5.3L
Transmission: 4L60E
very much not practical, although it is very possible.
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Old Aug 20, 2003 | 10:43 PM
  #10  
Sitting Bull's Avatar
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From: Calgary, Alberta, Republic of Western Canada
Car: 1986 Sport Coupé
Engine: 305-4v
Transmission: 700R4 and TransGo2
Originally posted by TunedPort 335
Have you dynoed it ?
Only with Desktop Dyno and asking for the considered opinons of guys like F-Bird'88 and Damon.

Here is the engine mocked up on Dyno2003. It shows it as having 334 hp but I don't believe that. I think 300 hp is much closer to the truth.
Attached Thumbnails 300hp 305-resize-screen.jpg  
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Old Aug 20, 2003 | 10:58 PM
  #11  
Damien00677's Avatar
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From: Dubuque, IA
Car: 2006 'Nox 91 Camaro RS 91 1500 Silv
Engine: GM 3.8L, 305 SBC, 350 SBC
Transmission: Auto, auto, auto
desktop dyno seems to be a bit pessimistic with stock engines and quite a bit optimistic with modded engines....anybody know why?
I got a demo and it told me that with my combo (2.8 w/some stuff) I am putting out like 220hp....theres no way
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Old Aug 20, 2003 | 11:03 PM
  #12  
Sitting Bull's Avatar
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From: Calgary, Alberta, Republic of Western Canada
Car: 1986 Sport Coupé
Engine: 305-4v
Transmission: 700R4 and TransGo2
Originally posted by Damien00677
desktop dyno seems to be a bit pessimistic with stock engines and quite a bit optimistic with modded engines....anybody know why?
I got a demo and it told me that with my combo (2.8 w/some stuff) I am putting out like 220hp....theres no way
It is because it doesn't have enough input variables for things like the intake manifold.

Dyno2003 has more features like this and should be in the ballpark for smallblock Chevs in the 350 range. It was designed around the 300-400 ci displacement model, according to the magazines that have tested it.
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Old Aug 21, 2003 | 01:39 AM
  #13  
Pablo's Avatar
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Car: Turbo Buick
Engine: 3.8 V6
i dont have dyno numbers just Gtech Competition numbers (like i always have to say, the new, fancier, and more accurate Gtech)
13.7@104.44 mph and a whole slew of 13.8s at about 104 solid, 85 degree weather (best 60 foot is 2.33, crummy tires, driver, and low compression with crappy 3.42 gears)

the engine is a 305 .030 over
214/224 flat tappet cam with 1.6 stamped rockers for .474/.498
edelbrock Torker II single plane
edelbrock 1405 carb with no choke
416 cyl heads fully ported by myself, stock valves though (no undercut)
about 8.8:1 CR
edelbrock headers and full exhaust

Im pretty sure im in the neighborhood of 300 hp

tomorrow im actually reinstalling my heads that have been milled + 3 angle valve job w/ undercut on valves, and some 1.6 roller rockers.

Im looking to go even faster now, if it works out as planned should be about 320 hp

Im gonna try and match this with TBI but 500 cfm is gonna be hard pressed to feed this thing.

For you i would suggest a similar combo with a carb since you just want to go fast. Actually i would suggest a 350 more than anything.
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Old Aug 21, 2003 | 08:47 AM
  #14  
Sitting Bull's Avatar
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From: Calgary, Alberta, Republic of Western Canada
Car: 1986 Sport Coupé
Engine: 305-4v
Transmission: 700R4 and TransGo2
That's excellent, Pablo. You running a stick?
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Old Aug 21, 2003 | 05:43 PM
  #15  
Pablo's Avatar
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Car: Turbo Buick
Engine: 3.8 V6
Of course, I wouldnt have it any other way
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