I have a stock 1989 Iroc-z with automatic transmission, 350 5.7L engine, and 2.77 gears. I have taken it to the track and ran a 14.8. What are some of the free mods that can be done to it?? And do they make a difference if all of them are done??

 

14.8 with 2.77 gears, not bad at all.

You can port the runners, plenum, base, but it wouldn't do much now. Uprade the TPI or ditch it for a better flowing setup. Your intake is holding you back.

There's a thread somewhere with a list of free mods but they are few and make little to no difference.

 

I'd get a set of headers and a cutout unless you have the money, do a cat back. Then get some gears. I had 2.73's and they sucked off the line. From a roll it wasn't to bad, but when I swapped out for 3.42's it was night and day. Those mods alone should dip you into the 13's. Heads & cam, with a better intake, should get you high 12's if you can hook right.

But don't ditch the tpi for another intake before you do basic mods, or else you will be sorry.

But 14.77 is pretty damn good. What was your 60ft?

 

https://www.thirdgen.org/techbb2/sho...hreadid=151240

 

If you aren't comfortable with building your own adjustable Fuel Pressure Regulator, just take the cap off your old one (I think it's a "Security" T15 or T10 bit) and put a nickle or quarter in the top and reassemble. Good for about 3-4 additional PSI in most conditions, which actually is almost ideal for a near stock prom/tuned car.

 

Are you the guy who posted a thread awhile back looking to get into the 13's?

 

Take off the intake duct that goes over the radiator, remove the air box piece. You'll see under both airboxes there is plastic material. Some guys have cut portions out, I just totally cut everything out so the filters have nothing under them. You can also do the throttle body coolant bypass, not free but it is cheap. Need to buy a new hose with a 90 degree bend on one end and re-route the coolant from the intake base right under the throttle body to the radiator. Currently it goes through the throttle body. Weight reduction is free, but depends on the owner. You could gut the interior and carpet, or ditch stuff like the A/C. Like already mentioned, porting the intake is free if you already have the tools. Do a search for more info on that one. People have also ported their throttle bodies. Thats about all the cheap/free stuff I know of. I say next mod for you should be a shift kit. Good bang for the buck. The rearend is probably a 9 bolt, gears are expensive.

 

First thing I did to my car was get rid of that miserable gear. Going to a 3:23 really woke up the car, gas mileage didn't suffer or maybe improved a bit. Not too many free improvements to be had, but running under 15s in the quarter is decent

 

Where can i get gears from? aftermarket or can i get them cheaper used from somewhere. How much do they run? How about installation, is that also expensive?

 

You have to figgure out what kind of rearend you have first. I'm guessing you have a 9bolt B/W rearend, but the other possibility is the 10bolt GM rearend. Once you know which one then you can price stuff out. Its commonly accepted that 9bolt parts are more expensive than 10bolt parts, but recently I've seen some pretty cheap gears for 9bolts on these forums, maybe try a seatch. Other than that sweet deal you'll have www.9bolt.com. If it turns out you have a 10bolt then you can price stuff through Summit or Jegs, probably end up being much cheaper.

 

Opening up the air duct.
Adjust throttle stop for 90* opening.
Removing TB coolant hose.
Blocking coolant bypass and changing or removing the tstat.
Removing all of the emissions equipment.
Getting rid of about 200 lbs of dead weight.
Increasing the initial timing a bit.

That's just a few of the free ones, but enough to get you down to about 14.0 or maybe better depending on how your car responds.
Highway geared cars tend to respond very well to weight reduction and anything that picks up the torque like getting the intake and coolant cooler.
If you go to block off the EGR, block the heat crossovers in the heads to keep the heat from ever getting into the intake. Just disabling the EGR won't get you any significant gain like blocking the exhaust crossovers will do.

If you're going to do any MAF mods, then have two MAFs (one completely stock). Drive around and to the track with the stock one, then put the ported one on right before you make a pass.
Running the ported one all the time can make your WOT too rich and cost you power.

 

u can grind out the little air dam right behind the throttle body in the plenum. get an adjustable fuel pressure regulator (not free but cheap) port the plenum to match the runners take the screens off the maf and do as i did and make a homemade cold air kit for about 30 bucks. headers range from anywhere from 150 to 450. get an airfoil only about 20 bucks. thats about all the free n cheap mods i can think of without going into the motor. ive heard by swapping the cam can give u another 50 ponies on a stock l98. thats about 200 or so. im not sure how much horsepower youll gain after all that but it should help quite a bit.
also dont forget a k&n air filter.. they claim like 15 horse with a k&n another 5 to 7 with afpr 20 to 40 with headers another 10 or so with cold air. air foil another 5 or so and another 5 to 7 by porting ur plenum and grinding out those air dams....... there put there to quiet down the air as it rushes into ur motor. and another 5 or so bye removing the screens off ur maf and grinding out the heat sinks.............. good luck........... if u do all this and go back to the track tell me how much it helped

 

The 10 bolt can be a 7.5 or a 7.65.
I paid $800.00 for a 3.73 Richmond gear and the bearing kit. That was installed.
I would not recommend taking the screen out of the MAF. For the smallest gain....its not worth it if your motor swallows something!

 

My vote is dont F with the MAF sensor, i know some people have seen gains and have no driveability problems but just seems like a risky endeavor to me.

The 2.77's make a big diff. go with more gear.

Ram air ducts are easy and cheap,

Hogg out the intake manifold cost ya the price of the bits big sotp diff.

A little more initial timing then stock is good your going to have to play with it a little to see where your car responds best.

Cheapest speed mod ever practice your launch! (Whats your 60'?)

Your stock exhaust is very restrictive, stock manifolds are horrible, a cutout can be a great addition (cheaper then aft cat exhaust and less backpressure) headers and a Y pipe well also help a lot (my vote is have them coated b4 install well worth the price) A little more stall would do you good too but thats getting into the more expensive stuff... Good luck

 

my 60' is 1.9 on crap tires, so it could POSSIBLY be better

 

If that's true you are one hell of a driver.

Youv'e already done the good driver mod, hehe.

 

Someone above asked for the guy looking to get a stock 350 TPI into the 13's,,,,,that would be me.
I am much like the guy that started this thread,,,,I have an 88 350 Iroc that was bone stock,,,,mine ran 14.60 at 94 mph also with the 2.77 gears,,,(yuk) my 60 foot was in the 2.1 range with no tire slip,,,literally floor the car and it just learched on,,,a dummy could drive mine,,,lol. I had played with timing on mine,,,,I found the base timing could go no higher than 8 degrees on mine or serious knock would accur,,,,8 degrees is where it ran the best so I left it there. I have done the free mods as well,,,,but they won't get me in the 13's though. I have begun some bolt on mods and plan on going to the track next month when they open to log some more times,,,,I have more bolt ons waiting,,,one at a time with real track time results is my goal,,,hopefully to help everyone here. So far I still have a stock L-98 with hooker headers and Y-pipe installed and a Edelbrock cat back exhaust system. This mod alone really woke the car up,,,I highly recommend it,,,,I would say it was the headers and Y-pipe more than the cat back exhaust,,,,now I can roll out, (trans in drive) and going about 5 mph I roll into the throttle,,,still in first gear,,,and it starts hazing the tires and fish tailing through most of first gear now,,,then bites and goes,,,jumps sideways on the 1-2 shift. This car never did that before unless I was completely stopped and brought the engine up against the converter,,,only then it would spin the tires. Feels like a solid 20-30 hp gain to me. I am hoping this will get me in the 14.20 to 14.30 range still with 2.77 gears,,,,other mods sitting in boxes are,,,,adjustable fuel pressure regulator, 1.6 roller rocker arms. I plan to port on the upper plenum only behind the throttle body,,,I plan to leave the runners alone at this time. I am going to see if the adjustable fuel pressure is truely worth any time also,,,I will start with stock 44 lbs setting and go up from there and log my times, I am pretty sure with a little more fuel pressure I might be able to get away with a little more base timing as well since I think the car is a little lean which is why it's sensitive to detonation,,,more fuel will help quench that to some extent,,,,, so I have a great tuning tool to use once installed.,,,I am going to try to get the car into the 13's with the stock 2.77 gears. I just picked up a 3rd gen 7.5 rear that I am getting ready to completely rebuild with 3.23 gears, 28 spline moser axles etc....that will go in the car only after I have exhausted all attemps for 13's with the 2.77's. (Damn Aussie rear) getting rid of that later this summer. Keep us posted Antman,,,possibly you and I can share info and help each other to make our cars a little quicker. Larry.

 

The 2.77's were not all bad. I got some good times with those, and could smoke the tires with them no problem. 3.42's are alot better for the 1/4.

 

Ya the 2.77's aren't bad,,,,I don't think the overdrive trans is necessary with them though,,,kinda overkill in that department,,,I am going to see how fast the car will go with simple bolts ons and keeping the 2.77's for now. I have a 10 bolt with 3.23's in the works already,,,but I wan't to see how the car does with 2.77's first. I think the only reason the 2.77's don't feel as bad is because the trans has a 3.06 first gear to get it moving,,,if it wasn't for that the car would be a turd 3.23's should make a nice improvement,,,,if I get the car in the very low 14's with 2.77's then I am sure the gear change will push me into the 13's and the car should be even more fun to drive. Can't wait for the track to open,,,Larry.

 

It would be easy for me to just throw the rearend in the car and do all the bolt ons now and get it all over with but I am so curious as to what each change makes so I am experimenting. It will take a few trips to the track and a few long nights on the car but I just want to see what works and how much it's worth.
I am dieing to install the gears in the car though,,,I have other cars with alot of gear,,,,4.10's and 4.56's so I know even a slight change to 3.23's in the Iroc should make it feel night and day. I have to quit talking about it,,,,I might just run out to the garage and start putting it in there Larry.

 

So did you ever go through with this? Just wondering how the results were. I am curious as to how fast my car will go. And if the Head's, cam, and headers are gonna be worth it.