move this if you have to but i cant find a better forum to post it in. I am buying a 350HO crate engine, i got talked out of the recon. Anyways, I want to know what mods i can do to add to the 350HO's 330 Horsepower and 380 Torque. 330 horse is the dyno with open headers and no accessories, so i want to know what type of internal engine mods i can do to add some more horsepower. here are the engine specs:
9.1:1 Compression Ratio
Cast Iron 4-Bolt Block with One-Piece Rear Main Seal
Nodular Cast Iron Crankshaft
Cast Aluminum Pistons
PM Steel Connecting Rods
Cast Iron 64cc Chamber Vortec Cylinder Heads with 1.94'' Intake and 1.50 Exhaust Valves
Dual Pattern Cam, Lift: .435'' Int. / .460'' Exh., Duration @ .050: 212° Int. / 222° Exh.
1.5 Ratio Rocker Arms

Is there a better cam i can run that will still be as streetable? how much horsepower would larger ratio rocker arms and a cam add? any other ideas? thanks.

 

I bought that engine and put it in an 87 IROC 5 speed w/ a 3.45 rear. Here is the set up I went with. I pulled the vortecs off, milled them .020", valve job, pocket porting and opened/polished exhaust port a little. I put GMPP 1.25" springs on them (supposed to be good to .525") and added 1.6rr's. I used the XE 268 cam (224/230) and uesd the edelbrock rpm intake and holley 650 dp. I didn't get it on the dyno before I sold it, but I pulled a LS1 on a roll. I expected it to hit 105-108 in the 1/4, never got to see however. It ran really hard from 3,000rpm on up to 6,000rpm. When I sold the car, I took the kid for a ride and while in second gear at about 40mph, stomped it and spun the new 255 SZ50s hard

 

Well, first off the cam is certainly on the weak side. The CompCams XE262 is a slight upgrade and is certainly streetable, 218/224 @.050 with .462/.469 lift (I run that cam in my vortec headed motor). The XE268 is a little bigger still and quite alot of people are running that with Vortecs. Any more lift and the springs will become a problem and you will run into valvetrain clearance problems (it's borderline/right on the limit with the 268 already...) By the way I'm assuming the motor is a non-roller cam setup to start with. I can't remember for sure if it is or not.

The intake they rate that engine with is also the GM vortec dual plane I believe, about comparable to a Performer from Edelbrock. Using the Performer RPM should at least give a couple ponies I would think (I'm using that intake, seems to perform well)...

Any other mods than those will require some decent disassembly of the motor and some more work. Like having the compression raised by milling the heads a little bit. Which while that is being done would be a great time to have a couple things done to the valve springs/related items to allow for more lift on the cam. Then you could run on up over .500 lift and make some more power still... Having the exhaust valves back cut and a little mild porting done would benefit you as well.

Just depends on how much trouble you want to go to.

If you just want to go the cam/intake route you can make up around 375 hp with the XE268 and RPM intake. If you do the head work and run a larger cam you can easily make up over 400hp...



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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

 

thanks for your help. so with the cam swap, do i need to do any other work? you mentioned two, which do you feel suits best a weekend car i drive for fun? as long as there are no probs i would love more horsepower, as long as i still idle well. thanks

 

I agree with the above post, do a simple cam/lifter swap and add an RPM inatke and good carb and you should be set. I wouldn't pull the heads or valvetrain. Just a cam/intake swap.

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350 4 bolt main, Speed-O-Motive 383 stroker kit, re-sized rods ground for clearance,TRW Forged pistons,10.7:1 compression,HPC Coated RPM intake, Holley 750 cfm carb,World Products Sportsman II heads,2.02/1.60 valves, Comp Cam 1.6 roller rockers, Comp Xtreme 284 cam,240/246@.050 with .540 lift,Crane pushrods,ATI damper,Proform HEI and MSD6A box,HPC coated 1 5/8 headers, 2.5" exhaust with 40 series mufflers,TH350 with Hughes 3000 stall, Powertrax NoSlip Locker, 4.11 gears.

 

looks like a vortec convention around this place, the Xe268 cam is a sweet choice...Ill agree with the other guys on this one .

Oh wait...I have one- cool

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91 RS W/carbed 350, Vortec heads, performer rpm, Comp cams Xtreme energy 224/230 duration and .477/.480 lift. BFG Drag radials. 3.42 posi,Corvette servoed 700r4, 3000rpm stall converter. Edelbrock TES, 3inch cat, flowmaster with single 2.5 inch exit.
Best time yet to come
13.0 @ 107- N/A
12.5@ 117- 100HP Nitrous

This is a Pic of my car in race trim www.tbns.net/billyjay/camero.jpg

Yes I know how to spell camaro- so dont ask. I didnt make the link