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270hp plus out of a 305.

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Old Oct 17, 2012 | 08:00 AM
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Buggy Disaster's Avatar
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Car: 91' Z28. 70' Dune Buggy
Engine: LSX Cam/Full Bolt ons
Transmission: T56
Axle/Gears: 4.10
270hp plus out of a 305.

I've got a 305tpi with over 160k miles as my daily driver. Can I reliably pull off the following mods.

Hooker headers and y pipe ~18hp
Gutted or magnaflow cat ~5hp
Cutout after the cat ~6hp
Fog light ram air mod with K&N filters ~5hp
Slp runners ?
Lt1 cam ~30-40hp
Tune

How much HP would i be at? I'm thinking around 270-290 at the crank

Last edited by Buggy Disaster; Oct 17, 2012 at 09:27 AM.
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Old Oct 17, 2012 | 08:08 AM
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Car: 88 camaro irocz
Engine: l98 tpi
Transmission: 700r4
Axle/Gears: 2.77
Re: 270hp plus out of a 305.

get something like ebl flash to tune it with . chevy gave us growing room on the tune .
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Old Oct 17, 2012 | 08:42 AM
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From: Long Island New York
Car: 89 Formula 350
Engine: Forged 385 H/C/I
Transmission: 700R4-4300 Stall-lockup
Axle/Gears: BW 9 Bolt 3:70
Re: 270hp plus out of a 305.

At the rear wheels those mods would put you around 230-235 at best. If you wanted 270 rwhp out of a NA 305 you will need a much larger cam then the tiny lt1 cam and head work.

Last edited by TPI-Formula350-; Oct 17, 2012 at 08:49 AM.
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Old Oct 17, 2012 | 09:51 AM
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Re: 270hp plus out of a 305.

270-290 crank is feasible. Lt1 cam wont give 30-40 hp tho. Like above said i think it may get 230 whp which is close to 270-280's hp on motor

I have seen peanut cam bolt on cars dyno near 200whp so mild cam setup could be 220-230 with supporting mods and great tune. Id go abit larger than lt1 cam tho
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Old Oct 17, 2012 | 10:01 AM
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From: Georgia
Car: 91' Z28. 70' Dune Buggy
Engine: LSX Cam/Full Bolt ons
Transmission: T56
Axle/Gears: 4.10
Re: 270hp plus out of a 305.

What cam would you reccomend for better perfornance?
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Old Oct 17, 2012 | 10:23 AM
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Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 270hp plus out of a 305.

Xe comp grind or lunati voodoo type in the 212 deg at .050 range but heads would need slight mods to handle the lift. Basically step up from stock. Cranes 2032 cam would work and fit stock heads but its pricey for unknown reasons and harder to find these days.

zz4 could also work but its abit bigger on lift on exhaust side which will make it harder to fit on the heads. Could try alex's parts spring kit for lift clearance. Guy here used it on vortec heads on a .540" cam and it seems to work.
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Old Oct 17, 2012 | 04:53 PM
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Car: 91 formula
Engine: 350 tuned port. bolt ons
Transmission: 700r4
Axle/Gears: 3.73
Re: 270hp plus out of a 305.

Originally Posted by Orr89RocZ
Xe comp grind or lunati voodoo type in the 212 deg at .050 range but heads would need slight mods to handle the lift. Basically step up from stock. Cranes 2032 cam would work and fit stock heads but its pricey for unknown reasons and harder to find these days.

zz4 could also work but its abit bigger on lift on exhaust side which will make it harder to fit on the heads. Could try alex's parts spring kit for lift clearance. Guy here used it on vortec heads on a .540" cam and it seems to work.
I read the crane cam 3032 is great for a 305-350 engine. I wonder if it would hurt mpg.
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Old Oct 17, 2012 | 09:59 PM
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From: VA
Car: 88 camaro irocz
Engine: l98 tpi
Transmission: 700r4
Axle/Gears: 2.77
Re: 270hp plus out of a 305.

springs an retainers for .550 lift cam in the 305...
http://www.jegs.com/i/Manley/660/22410-16/10002/-1
http://www.jegs.com/i/Manley/660/23652-16/10002/-1
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Old Oct 18, 2012 | 12:33 PM
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Car: 1986 Camaro SC
Engine: 305 TPI Procharged D1SC
Transmission: Tremec TKO-600
Axle/Gears: Moser 12 Bolt 3.73 posi
Re: 270hp plus out of a 305.

i like my crane 2032 cam.
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Old Oct 18, 2012 | 07:17 PM
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From: Georgia
Car: 91' Z28. 70' Dune Buggy
Engine: LSX Cam/Full Bolt ons
Transmission: T56
Axle/Gears: 4.10
Re: 270hp plus out of a 305.

I think I would prefer not to mod the heads If I upgrade the cam. What other options are there istead of the cranes cam, I cant find any for sale.

How much hp gain am I looking at with one of these cams?
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Old Oct 19, 2012 | 07:26 AM
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Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 270hp plus out of a 305.

Just need something under .470" lift which is gonna be hard to find. Lunati had a few cams. Could have a custom low lift grind done for yah as well. Call mike jones at jonescams.com.

I am pretty sure if you ran beehive springs like comps 26918 set you can run closer to .500" or more. i know vortec guys do this alot. You could run one of the smaller comp grinds in that case which come in at 490-510" lifts

Other method is offset locks and shims. Buy .050"+ offset valve locks and about .050" worth of shims. Commom shim packs are .015, .030, and .060 so you can stack up to .045 or tighten up to .060". Run a good double spring like patriot golds. That will give you near .520"
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Old Oct 19, 2012 | 07:47 PM
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From: Minneapolis, MN
Car: currently a 91 G92.
Engine: 305TPI
Transmission: Borg Warner WC 5 speed
Axle/Gears: 3.42
Re: 270hp plus out of a 305.

I like my comp cam xr258hr12 206/212 @ 0.50" .480"/.488" on 112* LSA. Would make a huge difference on a peanut cammed lb9.
It really woke up my car, especially after a good tune considering I went up from the L98 cam that came stock in my car.
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Old Oct 19, 2012 | 10:37 PM
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Re: 270hp plus out of a 305.

Are you planning to do a fresh rebuild or tuneup on the cylinders, rings? 160K is a lot of miles on a stock 305 and may be a huge risk of failure if you just add the cam and headers.
Had my dyno done the other day. 91 z28 305, 700r4 auto, Headman Shorties, Comp Cam 268/479, 1.6 roller rocker tip, new lifters, push rods, no cat, Magnaflow dual exhaust with 3inch header back pipe, and a TPIchips.com programmed chip......was getting 296HP at motor and 259HP at rear wheels!
Now the bad thing is I still hadnt gotten my idle issues worked out after building it up like this. but keep the fuel going and she runs bada$$!!
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Old Oct 20, 2012 | 11:52 AM
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From: Minneapolis, MN
Car: currently a 91 G92.
Engine: 305TPI
Transmission: Borg Warner WC 5 speed
Axle/Gears: 3.42
Re: 270hp plus out of a 305.

Originally Posted by white_ghost
Are you planning to do a fresh rebuild or tuneup on the cylinders, rings? 160K is a lot of miles on a stock 305 and may be a huge risk of failure if you just add the cam and headers.
Had my dyno done the other day. 91 z28 305, 700r4 auto, Headman Shorties, Comp Cam 268/479, 1.6 roller rocker tip, new lifters, push rods, no cat, Magnaflow dual exhaust with 3inch header back pipe, and a TPIchips.com programmed chip......was getting 296HP at motor and 259HP at rear wheels!
Now the bad thing is I still hadnt gotten my idle issues worked out after building it up like this. but keep the fuel going and she runs bada$$!!
259hp at the wheels is a good bit over 296 at the motor. You lose about 20% through the drive train with an automatic transmission. That should put you at over 320 hp at the crank.
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Old Oct 21, 2012 | 05:35 AM
  #15  
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From: VA
Car: 88 camaro irocz
Engine: l98 tpi
Transmission: 700r4
Axle/Gears: 2.77
Re: 270hp plus out of a 305.

i'm 85 % dc on 10 psi of fuel pressure @ 5000 rpm . using the ebl flash utlity i should be around 267 bhp which is only 213at the wheels . with mods in my sig minus the t70 turbo .lol
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Old Oct 21, 2012 | 09:22 AM
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Car: 1992 Camaro RS
Engine: Vortec headed 355, xe262
Transmission: T56
Axle/Gears: 9-bolt 3.70
Re: 270hp plus out of a 305.

The XE cams are good, but they are flat tappet. You have a roller motor and have the potential to run a much better roller cam.

A combination of LT4 hotcam, comp 787-16 retainers, and some LS2/LS3/LS6 springs should work to get you the clearance/pressure you need if you balance it out right for around $400 or so. You just need to be careful with retainer-guide clearance, you should have plenty, but just check first. Its always a lot better to have to return/sell new/barely used parts because things arent going to fit than it is to bend some pushrods and start breaking parts left and right.

Consider investing in a spring micrometer for beehive springs if you go that route, that way you can know exactly what your installed height is and what your open/seat pressures are.


BTW the good thing about hte LT4 hotcam is that it was intended for 350 LT1's, and makes great power with those and with Vortec headed 350s. Vortec heads are lift limited to around .470 lift also, and the beehive springs (Comp 26918) are the solution. They are expensive however.

The factory LS2/LS3/LS6 springs are also beehive springs and are MUCH cheaper. Beehive springs are much more modern technology, reduce valvetrain mass, and are generally an improvement over traditional springs. Unfortunately the LS2/LS3/LS6 valve springs are very weak, so they wont be able to handle the ramp rates of a more modern, more aggressive Comp XR series roller cam. But an LT4 hotcam is perfect for them.

So the point is that you make slight sacrifices in ramp rate aggressiveness for less stringent requirements on spring pressures, which allows you to get cheaper valve springs and worry less about them wearing out. And then when its all said and done, you can go to a vortec 350 and throw the same valve springs and cam in that engine and make even more power.

The LT4 hotcam:

http://www.summitracing.com/parts/nal-24502586/

But with any cam worth swapping to, it requires other work, namely headers/exhaust/stall/tune work.

Any cam that will work with the stock stuff you have is not worth the work and cost of swapping. That includes factory LT1 cams, IMO.

Last edited by InfernalVortex; Oct 21, 2012 at 09:28 AM.
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