This is my first post on these boards, and I've seen a lot of helpful information in just the few weeks I've been looking around here.

As for the title of my post, I've got a 1986 IROC-Z, with a 305 TPI. It's completely stock, as far as I know, and I want to bring it up to somewhere in the 350 rwhp range. What would some of you suggest for engine/transmission/exhaust modifications? I know it's vague, but there's really not a lot to tell about the car.

Right now, an engine swap is out of the question, though if it looks like a pipe dream for 350 horses at the wheels, I have a 1980 Z-28 with a 350 in it that I can pull and rebuild. I do want to see what I can do with this 305, first, though, as there's some sentimental value in the '80, and I don't want to tear it apart if I don't have to.

TIA

 

Getting anything over 300 RWHP is pretty much a pipe dream with TPI, period, out of any size motor. The induction simply doesn't flow enough for that, and the "tuned" nature of it results in "tuning" for a torque peak at around 3600 RPM at the expense of "de-tuning" at RPMs above that. Even 250 RWHP is a major stretch for a 305 TPI.

Your goal needs to be re-evaluated if you intend on retaining TPI.

 

Yep. You could just buy a crate motor, ready to go.

 

Alright, just based on those, I'm thinking I should lower my sights a little... Here's what I'm looking for: Something that takes off like a bat out of hell, and makes appreciable top speed. I'm satisfied with what I have now, but only because I have to be.

There are several things I know I want to do with this car. They are, in no particular order:

Exhaust: cat-back at least, most likely switch over to headers and a high-flow cat as well. Brand recommendations would be appreciated.

Intake: Looking for suggestions on this end. I dropped in K&N Filterchargers last week, and I'm feeling a little difference, but not enough to keep me happy for long. I've seen the mods for creating a ram-air system over in the tech articles pages, and I'm wondering what that will do for me. There's also either a turbo- or supercharger on the wish list, but that's not coming for a while.

Transmission: Anything that can be done? It's an '86 stock 700-R4.

Rear Wheel Gearing: I've got an idea what difference different ratios will make, but I'd like to hear what works for different people.

The crate motor idea sounds great, but it's one of those "not if I can be happy with improving what I have" situations, because it'd take a while to get that kind of money together to drop all at one time.

Again, thanks in advance.

 

I'd go for Hooker headers and Hooker cat-back. Sound clip in the sig, this is a great starting point.

3:42s work best with TPI induction.
And a higher stall TC would help greatly.
Get those things I mentioned and you'll be at low 13s easy.

 

i hope you meant low 14's....

 

Doh, I was thinkin he had a 350 already..

 

Its going to be hard, but you can get close anyway I think:

"1991 Camaro Z28
350 L98 w/ T56 (originally 305 LB9 w/ T5)
318 RWHP, 419 RWTQ
12.803 @ 108.50 MPH (1.923 60')"



Ported L98 heads, other than that I am not positive whats in the car anymore. I think LT4 Hot cam, TPIS base, larger runners, SLP 1 3/4" headers.

 

How did you go from 350rwhp to modding your 305? If you didn't plan on changing every single piece of that motor, including the block, you'd never see close to 300rwhp n/a and with any degree of ease.

To give you some idea, full exhaust and a lot of intake work could probably get you almost 190rwhp on a decent condition 305 without any other work.

 

First of all you need to set a more attainable goal. I don't know about what you mean by "take off like a bat out of hell" but 350 rwhp is no joke and is a lot faster than you think. Consider this too...after you go through all the trouble of making that power you have to set your car up for it (suspension, tires, tranny, rear-end=$$$$$$). First thing is you need to figure out wheter you're going to stick with the 305 or put in a 350. My recommendation is junk the 305 anyway and drop the 350 in so you have yourself a solid foundation for mods now and bigger mods in the future. Now again you need you need to know what your goal is and then consider other factors like cost and how trashed your 305 is at this point. 275 crank horsepower will get you into the low 14's/high 13's, and thats plenty for the street, which can be accomplished fairly easily with either motor.

 

rezinn: I got from 350 rwhp to modding a 305 based on the first couple replies saying, basically, exactly what you did. If I want to get even close to that kind of power, it's going to take a lot more than I expected, so I have to aim a little lower.

RedFirebird: 275 crank hp on a 305, easily? Based on what I have now, that would most likely be what I was looking for as far as performance. Assuming I keep the 305, what do you think it would take? Even if it ends up being redone completely, at least I'll have an idea of what kind of time and money costs I'm looking at. I understand that the 350 is a better foundation for building on, but like I said, if what I want is feasible with a 305, I'd like to go that route first. If the difference in cost (money and time) is that significant with the 350, I'd do the mods to that one, and drop it in when it was done. It looks like that's how it'll end up being anyway... So in your opinion, what'll it take?

 

The biggest factor in deciding what you're going to do with your car is funds. How much are you looking at spending? If you can do some work yourself, or have friends to help, it will be more affordable. Another thing you may have to deal with is emissions, is that necessary?

 

Right now, I can see spending $5k-$7k on the engine alone, spread out over time. Low-end mods first, with the car off the road as little as possible, and then saving for more expensive mods. It's a project/daily driver, which isn't a combination that works too well, I don't think.

I've also thought about pulling the 350 and building it, while leaving the 305 as is. It sounds like that might be the best way to go, based on Mark A Shields', madmax's, and RedFirebird's replies. If I went that route, I'd spend the same on the engine, possibly a grand or two more. It sounds like I'd have to go with a carb intake to make decent power, rather than TPI.

So with a 7 grand budget, a lot of time, and some friends to help, what do you think I can end up with?

 

That's quite a budget. One word of advice. If you plan on spending 7k, only try to spend about 5-6k and the rest will take care of itself

The best idea would be to build your 350 up while the car is running and drop it in later. Don't let TPI ruin your perception of fuel injection, 350rwhp could easily be made with a different intake like the LT1, super ram, or stealth ram. Don't overlook an even larger engine, it would be possible to build a fuel injected or carbed 400 or larger engine. Search the boards and read up on things to help you decide what is best for you.

Don't forget that more power = more broken parts. Transmissions and rear ends are expensive. My repair costs this year way exceed my mod costs