Hi everyone. I just recently purchased an 89 IROC 350 tuned port. I have discovered that the engine smokes at startup, and it has an intake leak. It would seem that it at LEAST needs a top end rebuild. (Pending a compression test to determine the state of the bottom end).

When I rebuild the top end, I would hate to do all the work, and have simply a stock L89. However, at the same time, I'm trying to force myself to compromise and not build something radical because this is just a daily driver, and I dont want to wrap too much money into it, as I have another project I'm working on.

Here's the goal. I'm looking to make 300-350 horsepower (flywheel). I am planning on buying shorty headers, and 3 inch catback exhaust. My question lies on what heads and cam I should used to achieve these Numbers. I am curious what cam I could use to get that number with the Vortecs. (preferably with low enough lift that the heads do not require modification). Or if I could achieve these numbers with the stock heads, with maybe some minor port work, what cam should I use? I would like to get away with the stock heads so I can save from buying the expensive Vortec base. I would also like to keep the stock Throttle body, and Injectors (as long as they are all good) But I will probably experiment with some programming. Bang for my buck is what I'm looking for here, guys. I will put it back stock, if I must, but I'd like to gain a little extra while I have it apart.

Thanks in advance.

 

Sorry, L98, not L89. Damn dislexia.

 

100 shot of nitro would work....

or you could go with a mild, lt1 or lt4 cam
spend a good week porting your heads, researching, port somemore
Learn to tune your own computer, if you don't know already... that should put you above 300 hp

 

On that note. Perhaps the stock L98 heads with some port work done to them. Would an LT4 cam provide adequate lift with the stock 1.5 rockers? Or better yet, not provide too much for the stock springs? I think an LT4 "hot" would be a little much for my setup.

The high side of 300 hp, and for the car to run high 13's while being very drivable, reliable, and still decent on gas is my goal.

 

i agree the "hot" will be too much lift for the stock springs... you can pick up a lt1 cam for like 60-100 bucks, the prom equipment is anywhere from 150 to over 300 depending on how many bells and whisles you like... porting is all in how much time you have...

guessing about 20-30 ponies from the cam
another 20-30 from the head work
and those with properly tuned (ECM) probably a mid-high 13sec car with around 300hp... and if you want a little pick me up, a vette converter would help a bit, maybe a .1 or .2... from having a little bit higher stall

...this is all assuming that you will help out the exhaust some (headers/catback)

 

1st off, the smoking at the start up is a pretty easy fix. Just buy a new set of valve seals. Mine did the same thing on my TPI. If your going to be messing around with the top end. Your going to need an ajustable fuel pressure regulator, I would recommend new springs with a new cam. Your lifters should be ok. A ported plenum would be a good thing. Also depending on the $$ you might want to think about a new intake set up. I bought the edelbrock Hi-Flow intake and runnres for my car.
Hope this helps.

 

It doesn't look as though there would me much of a difference in the LT4 production camshaft, and the LT1. If you're running 1.5 rockers, which I intend to do, to at least start with, they seem to have similar lift, and duration numbers. Anyone have any more insight?

Also, if I can find a good deal on a set of heads, what kind of numbers could I put down with a set of stock Vortecs, Edelbrock hi-flo base, ported plenum, LT1 cam, stock runners (for now), headers, cat-back, 1.5 rockers, ecm reprogram, and stock fuel system? I may be able to work out a trade with someone. I've got a laptop, and OBD II software and interface to sell. I have no use for it anymore as my newest vehicle is now the Iroc. haha

Thanks for the great info, guys.

 

you can probably get away with the factory base ported...but you will need different runners... they are a bottle neck...

now your getting into some real money here....

well really Smoggey-Dickey's sells a combo close to that "hot"ed and advertises around 350hp....

BUT.... I'm sure it lost 5mpg....

If around 300hp and mid-high 13s is your goal...stick to it
there are plenty of 13sec 350TPIs that have a close to stock intake
(save $ for exhaust)
just get a cam with power below 5000...whatever it is...lt1 is just a cheap method
don't HOG out the heads (factory ones) just contour them better, (use the search engine on 083 heads)

giving that your car runs like most factory L98s your in the 14.9 range...tuning alone can render our cars into 14.4-14.5 second cars, so tuning is key to all

 

I'm running a ZZ4 cam with SLP headers and I'm extremely happy. I'd guess I've got numbers in the upper 200's at the flywheel. Don't really care too much about numbers but it REALLY made a huge difference, and if ya figure factory numbers in the low 200's when new....

....keep in mind the LT4 Hotcam is advertised with 1.6 rockers. Running 1.5's with this cam will keep it pretty mild, but still well over the stock L98 or LT1 cam.

My ZZ4 cam run great on the stock tune too. Yes I'm giving up a few ponies I'm sure without a tune, but it runs so well I don't see a need to tune it right now.

...did I mention the ZZ4 CAM!!!!!

 

Thanks for the input, guys.

This is what I'm looking at.

Lt1 Cam
Ported L98 Heads
Headers, y-pipe, and cat-back
Aftermarket Runners
Pcm Tune
and MAYBE (If I can find one priced decently used) an accel, tpis, or edelbrock base.

Hopefully this will put me over 300 flywheel HP.

One final question. What should I degree the cam at when I install it? Should I advance it, or just line up the dots on the chain, and set it at the distributor? I havent done a lot of engine work that dives this deep.

 

the LT4 hotcam really isnt that big, and the matching springs are like $40 shipped from gmperformanceparts.com

 

How much of an advantage in horsepower would the "hot" cam give me? Also, how much will it hurt my mileage, and drivability?

 

I'm trying to avoid getting too deep into the engine. Once you have a hotter cam, you think you need better heads to take advantage of it, and so on. I'm just looking for a nice daily driving car. Just want it to be fun to drive. I have a 79 trans am that I can mess around with making stupid-fast without worrying about it being docile.

 

The ZZ4 cam is a really good compromise between more power and still retaining driveability. Plus it runs good on a stock tune. The only iffy part about running a ZZ4 cam is the valve lift on the exhaust side is .510, so it doesn't hurt to upgrade the springs, and it's also a good idea to have the machine shop check the spring retainer to valve guide clearance. This is recommended for any cam exceeding about .470 lift. I had these things done so I could err on the side of being overly cautious. I also spent some time porting my 083 heads. I just matched them up to the stock fel-pro gasket size, smoothed the exhaust ports, and very minor bowl work. About the only upgraded cam I can think of that you could just throw in without worrying about upgrading your springs would the the Crane Compucam, but I think you'd definitely get more "bang for your buck" out of a ZZ4 or LT4 cam. Just my .02.

 

I like the cam I installed in my car. Actually got to play around yesterday. After trying to baby it a little because of replacing my set up. I was leaving a car show & people were waiting for cars to do some burn outs....My car actaully spun the tires through 1st gear and continued to spin into 2nd gear. I was pretty happy with my little 305.