Ok guys, here is the million dollar question. How do I build a modest 350hp motor, for as little as possible. I have been reading what everyone has to say about this combo with that componant. But I have not been able to see anyone really break it down and explain the BEST way to build a modest 350.

This is what I have: 87 IROC w/ 350 tpi (150k on motor), a 5spd t-5 has already been swapped into the car and it came with the 3.27 posi rear.

This is my overall goal: I want a 13 sec car, that gets 25 mpg with the A/C cranked on MAX. And that is able to pass any emission test. And I would like to be able to sit at 110mph all day long everyday of the week. I know I could get this if I bought a new SS or WS6, but I didn't I want to be able to enjoy my 87 IROC while competing with maybe even beating a new SS. And I would like to do this all for less than $2500.

So I thought instead of throwing out all my ideas I figured I would ask first what is the best way to get there?

 

Well you don't have to have 350 hp to be a 13 sec car. Anyways, have your engine bored and rebuilt. Next would be getting good flowing heads. I don't know what your budget is so I can't really tell you what would be best. I am going to use slightly used ZZ4 heads on my 350. They cost me $500 and only have 2k miles on them. Now with an engine it's all about getting air in and out. The better you do that the more power you will make. That means port your plenum, get bigger runners, etc. Also a well chosen cam is a good way for power. I am using a ZZ4 cam.

 

The in and out thing I understand...however I want to keep my TPI. If I use the ZZ4 heads and cam how will that effect my TPI or computer? I do NOT want to have to start getting into burning new proms or even getting a new ECM. I want as much as I can without touching the computer or sensors.
thanks

 

with a ZZ4 cam and heads, It should not effect your computer and the car should run just fine. Although If nothing else you should port the plenum as already suggested and upgrade the stock TPI baseplate to further increase your powerband with that combo.
Good Luck!

 

Port your heads, manifold, plentum and runners. Do all your own porting and run a ramjet cam with 1.6 rockers. Build your own adjustable fuel pressure regulator. Install headers with a new cat(s) and exhaust.

- 355ci, WS6, 5speed -
* Ported & Polished Cylinder Heads (Cast # 993)
* 2.02 & 1.6 Manley Pro-Flo Valves
* Harland Sharp 1.6 Ratio Roller Rockers
* Crane Valve Springs and Retainers
* G.M.P.P. Ram Jet Roller Cam
* Crane Roller Lifters
* Speed Pro/TRW 1.25 Dome Forged Pistons
* Windage Tray
* Lightweight Nodular 16lb Flywheel

* Induction - Ported and Gasket Matched
Plentum
Manifold
Runners
52mm Holley Throttle Body
Custom Built Adjustable Fuel Pressure Regulator
#19 GPH Injectors running at 50lbs

* Exhaust All New
Edlebrock Chrome T.E.S. Headers
High-Flow 3" Carsound Cat
Dynamax 3" Exhaust Tubing and Tail Pipes
Flowmaster American Thunder Muffler
Chrome Tips

 

Thanks for the ideas...

Thats pretty much what I had in mind however, what kind of compression will the domed pistons give me? I want to be able to run 89 or 93 octane. Would I be killing myself and or the cam if I just used flat top pistons?

Also when you say 355, do you mean boring .30 over? I was thinking about boring it but I didn't want to go much over .30. Also I do not want to mess with changing the crank. Just have it, the factory rods and new (maybe flat top) pistons balanced.

I already have the headers and muffler on order I'll take care of the cat in a few weeks. The car came factory with the 3" pipe, and it looks like it has been changed recently. What would be the advantage of putting a new pipe in (ie borla)? And the plenum is already ported with a matched fuel nozzles and a fuel regulator.

 

If you already have iron L98 heads you probably wouldn't get many gains from the zz4 heads. Porting your own is probably the best bang for the buck. I'd stick with flat tops with iron 64cc heads. Since you are going for 20+ mpg you probably won't have enough duration in your cam to take away to much of the static compression.

If you go with a cam like the xr269hr from comp cams and even just mild enough porting to get over 210 cfm of flow intake, you should be high to mid 13s with traction. But probably won't be over 20 mpg.

 

I am using ZZ4 heads and a ZZ4 cam on my new engine. Since I am converting from a 305 I went ahead and got LT1 24# fuel injectors and I will have the chip readjusted for the 350 and the larger injectors. As 85TPI400 said, porting your plenum will help. I did that using my Dremel and it was pretty easy. Just took awhile because I was really careful and made sure I did a good job. The ZZ4 heads are good heads but port what you have unless you can score a deal on some ZZ4s.

 

that can all be accomplished, just not that cheap. i'd say build a 355 with 6 inch rods, a lightweight forged piston with around 10.8 to 11.2 to one compression with fast burn heads. pick up some 1.6 to 1 ratio crane roller rockers with a stock LT4 or similar cam. to use them heads you'll need the vortec style tpi intake. use stock injectors with a custom prom. go for a gapless type of ring for the best sealing you can get. use a stock oil pump with a 5w30 or similar oil. also use a billet single row timing gear/chain set up if you can find it. a fluidamper lightweight balancer would also be a nice addition as well as under drive pulley's. using the best header cat back combo you can find as well as a cold air induction system with free flowing filters would be another help. as for the ignition system, a jacobs will work great or just a hypertech coil with the best wires, cap, rotor, and spark plugs you can get for it. when your going for gas milage and power like that, the idea is low drag, low weight, and overall efficiency.

 

If you make your engine as Zippy suggested make sure to save for a new tranny