I just bought a 92 Z28 Yesterday! It needs some TLC, I think it has an exhaust leak. I was reading some of the posts and the people on this site are very knowledgeable. The car has the 350 TPI engine. Does anyone have any advice on how to make more power to the stock engine? I am on a budget so I just want to make minor upgrades for now until I get more money. How can I make more power? Any help would be appreciated.

 

Welcome aboard thirdgen.org.

Let's talk budget first. A proper exhaust is going to run about $1000 (headers, high-flow cat, cat-back). An exhaust to support 450-500 HP will run a little more.

Anytime you spend money to increase power, you need to spend about the same amount to handle the power. Spend $1500 to make 300 HP, you're going to need to spend about $1500 to handle that increase (transmission/torque converter upgrades, rear end, suspension upgrades).

To make 450 HP out of a 350 is going to run somewhere between $4000-$6000. That means you need to spend another $4000-$6000 to handle that power.

So, how much budget do you have for the build?

 

Maybe I need to re-evaluate the amount of horses I want. I only have a few hundred bucks right now about $500. I was planning on just doing small things as I get the money until I get a lumpsome of money. I do want to eventually add new heads, cam, tpis intake, injectors,posi, shift kit, etc. But I will have to do it slowly. So what do you suggest I start with. The engine seems to be fine a minor exhaust leak I think. thnak you for responding! I'm far short of $4000 LOL!

 

Well i have a question for you what are looking to get from this car? I mean i know your saying you want 450-500 hp but my question is why? When ever i get into a build i have to figure out what my expectations for the car are in terms of performance (handleing, 1/8 mile, 1/4 stop light to stop light) , driveability, economics ect. So when you say you want 450-500 hp is that base on a performance goal or do you want that more for the sake of just having 450-500 hp. Reason i bring this up is to get 450-500 hp out of a SBC its got to be pretty radical which in turn decreases driveability and low end torque what you really feel when you launch from a stop light. Fuel economy and streetability decreases significantly as well if that actually matters to you. On the flip side you could build a very nice 350 with close to 400 foot pounds of torque in the lower RPMs and 330 hp or so and it will have greater acceleration (assuming the cars are equal no launches or differences in traction ect) and "feel" more powerfull from a stand still it wont be able to maintain that acceleration like a 450-500 hp motor but if this is your daily driver you wont really get many oppertunities to really use that high end hp and will enjoy gobs of low end torque for that pressed into the seat feeling. So what im tryin to say is if you plan on this being a daily driver i think you better re-evaluate your goals. Also start with a performance goal in mind and then figure out how much hp you will need to achieve it not the other way around.

 

thank you for your input! I really aprreiciated what you said. This car will not be a daily driver but I will drive it alot in the spring and summer seasons. I don't know if I need 500hp but it just sounds good to me! I dont want the car to be so fast that I cant drive it on the street, which is my main goal. I want a street rod not a drag car. So if you have any ideas on where I should start with the stock engine please offer any advice. I was thinking about upgrading the exhaust first. I like the sound of having low end torque.

 

Well the exhaust is a great place to start as the factory exhaust system is pretty crappy. The headers y pipe high flow cat performance muffler the works. The exhaust is probably my favorite mod as not only will it make a decent gain in performance but improves the sound immencly which to me is a big car of what a performance car is. Now with $500 you cant do it all so what ide start with is probably the cat back exhaust which can be done for around $500. You could do the headers and y pipe for about 500 as well and will probably give you a bit more bang for you buck but when taking in the sound into concideration the cat back will have much more of an effect which to me is worth more than the performance gain difference between the cat back vs the header and y pipe. Now if this is a car that will be driven on the street as far as hp is concerned i think youde be real happy with a 330-400 hp 350 vs a 450-500 hp motor. The reason is a 450 - 500 hp 350 would probably have a basic operating range of atleast 2500-6500 RPMs or worse a 3000-7000 RPM power band. This means it will only build power over thoes ranges and everything else suffers. Plus with a rev limit of 5500 RPMs builing power over that limit does you no good as you can never use it. This also means poor torque by comparisonas well as suffeing driveabiliy. What i mean by that is youll use a lot of gas vacuum may be so low that you may have to do some mods to make things like the vacuum assisted brakes to work torque to just get up and go from the stop light will be pretty sad a really choppy idle which sounds good but again not really great for street driveing. This will require a high stall converter and a steep rear end which will make the car scream at highway speed. So youde sacrafice alot and unless you actually intend to race it at the drag strip frequently will get none of the benifits. With a 330-400 hp motor youll have no driveability issues and it will be a fun peppy car that will do nice burn outs. With a basic RPM range of anything from idle to 5000 to 2000 - 6000 rpms it builds power in places you will actually use during normal driving. In addition to that adding NOS will allow you to have a nice streetable car that can still throw down the same numbers at the track as a 450-500 hp trailer queen. To me thats the equation for the perfect dual perpose street stip car that wont break the bank.

 

Do you think that I should get long or short tube headers?

 

Depends On one hand long tubes will provide better performance. There can be some fitment issues if used on a stick shift car if you ever plan to go that way. A custom y pipe would have to be fabricated unless someone actually makes one for out cars or go dual exhast which is challenging. There not street legal if that matters. There are also ground clearance issues to contend with especially on lowered cars. Alot of people argue with me on this but after they get done telling me there are no clearance issues its virtually always followed by i only bottom out when..... so point proven properly shorties never bottom out (unless you take it off roading or something really unreasonable that any exhaust system will have problems). Not to say that there isnt enough ground clearance to run them on the street as they only bottom out on crazy speed bumps and stuff like that but it does happen. So thats alot of things to concider for long tubes. Shorties on the other hand dont have the above problems. They do sacrafice some performance you just need to figure out how much is it worth to u?

 

If I may make a suggestion here.....

I remember when I got my camaro engine built and put in. It was awesome to have 500HP at the crank, but not so awesome that I couldn't use 1st gear, or anything more than 1/2 throttle in 2nd cause the engine was overpowering the suspension and twisting up the car. If you plan on doing any drag racing with the car, I would recommend doing the suspension work and subframe connectors first. In you car's current configuration, are you able to get all of it's power to the ground? Sometimes, having enough traction is key!! Anyway, as for engine power, I think that low 400's for horsepower are a great compromise between enough power and streetability. Edelbrock has a Performer RPM package that makes 420HP on 9.5:1 compression 93 octane pump gas, and if you shop around can do the whole top end for less than $2000-$2500. Then, going back to what five7kid said, you need to make sure that the trans/tires/suspension/ etc can handle it. Good luck with whatever you decide to do!!

 

Thank you! Where can I get this edelbrock Rpm thing from and what does it consist of? I'm not really trying to do any drag racing just on the street.

 

I don't think that you can buy a *kit* per se, but Edelbrock has done all the R&D on it and it makes what it makes cause they spent all that time and money into making sure the compnents were properly matched. Esentially you'd need a 350 block with....

Edelbrock Performer RPM aluminum heads
Edelbrock Performer RPM camshaft and lifters
Edelbrock Perfomer RPM(or RPM air gap) manifold
Edelbrock 750(or comparable) carb
Some type of 1 3/4 primary headers
A decent ignition system(MSD is a good one to have)
As close to 9.5:1 compression as possible

With those, you'd get about 420 flywheel horsepower. You can go on Jegs or Summit racing and find these parts, or you can do some ebay/swap meets to get them even cheaper. I believe that summit sells a home ground cam and lifter kit that has the exact same specs as the Eddy one for $50-$60 less.