hello everyone, Im kinda a noobie in the 3rd gen world. Ive got an 89 Iroc with L98 bone stock with 31k origional miles. Ive already completed all my suspension and gears, corvette servos shift kit ect.... I am now ready to do a light budget build. Basically i was wanting your opinions for heads and cam. I was wanting to stick with the stock intake even though its restrictive becuase of $. Im not going to be doing much racing or anything just looking for a few extra HP and that wonderful cam sound. Once again I am a noob so be easy on me and all advice is greatly appriciated.
Thanks,
Jake

 

There is so many options! Really depends. Are you planning on leaving the short block 100% stock? Your heads can flow decent numbers with some porting and the fact that it has only 31x miles it would be a shame to trash them for a set of aftermarket heads. Without porting I think you may be disappointed. To spend $900-$1,500 on a set of aftermarket heads is also something you will have to choose yourself. If you are willing to do that then the only choice is AFR heads, they have the best flow numbers and have great velocity. There is alot to know about heads, in short you want the best flow numbers with a smaller port volume. Example AFR 195's outflow Dart Pro 1 Platinum 215's by a significant amount. The difference here is the AFR's are more efficient. By having a smaller port and better flow you keep velocity up which in turn gives more power, responce, and a better air/fuel mixture. One of the best things about AFR heads is their mid lift flow numbers, they are great! On a street engine mid lift flow numbers are important and often overlooked, people make mistakes and only look at peak flow. Example- last engine I built I used AFR 195's on a 358ci SBC and went 10.97@123 with a 1.53 60ft on pump gas, drag radials, full exhaust, drove the car to the track and back home. Car made power from 2,000-7,600 just outstanding!

Now about a cam, this is a very crucial part that requires alot of knowledge and calculating to choose the correct one. If you would like to tell me ALOT more about your end goals and EXACT parts you will be using I can choose a cam for you, just shoot me a PM.

 

Hey thanks for the help, well lets just say I have a 100% stock motor, lets also assume I stick with the stock heads and have them ported. What kind of cam would you recommend to get the most improvement over stock? I agree I would like to keep the engine with about as many origional parts as possible. Literally this car is barely broken in. It has sat in a garage under a car cover about 95% of its 21 years. Hp goals are probably around 300-325 to the wheels. I sometimes run at the track on friday nights for fun and quickly realized tires, suspension and gearing showed huge improvement over stock. A nice cam and a little head work would make me happy and I would be satisfied. I just have no idea where to start as I am not familiar with cam's and what is the proper setup for a stock heads ported

 

ps ...I also havent touched the exhaust/manifolds it is bone stock. I also plan on a good set of long tubes, and a nice full exhaust system.

 

I would start with a set of Hooker 2055 shorties and a 3" catback. Long tubes are nice but you'll get almost as much out of a set of shorties and you won't have to custom fit the exhaust. Headers and a good flowing exhaust will be good for freeing up 15-30hp depending on the motor so I'd start there before doing any head/intake work. Also, make sure you gasket match your headers and heads (cutting the gasket on the inside ot match the exhaust holes. on the head and intake) I'd recommend porting your stock heads (and port matching them to your intake) and maybe picking up a Edelbrock performer intake. It's one of the better emissions legal intakes you can get if you are keeping your emissions.

 

Ok I have chose a few cams for you, however I am not sure if the 89 had a factory hydraulic roller cam or hydraulic flat tappet so I just chose one of each. These cams should work very well. In the end I don't know how much "thump" you had in mind for the cam sound but you should hear these some. Most peoples first mistake is putting too much cam in an engine to sound cool and the end result is it under performs. These should give you some extra ponies and keep alot of the drivability. I use Comp Cams in every engine I build so these are their part numbers.

Hydraulic Flat Tappet cam kit K12-366-4(NOTE-these are a kit with all you need
Hydraulic Roller cam kit K08-503-8

Will you be doing the engine work? Your heads will require machining for the new valve springs. You need to take your cam card with your heads to the machine shop so they can set up the correct installed height for your valve springs. Also you will need to use 1.6:1 ratio rocker arms, now would be a good time to get a set of full roller pieces Summit Racing brand are pretty nice and the price is not bad. If your factory rockers are 1.5:1 ratio you will also need to tell the machine shop regardless that you will be using 1.6:1 as this will affect (add) roughly .030 more valve lift on top of your cam card specs. All of this is to prevent coil bind of the valve spring, if that happens BOOM, not good! When you assemble the engine you will need to clay the valve relief in the piston to check piston to valve clearance, double check your coil bind clearance, check that the rocker arm tip is in good center alignment with the valve stem as you rotate the engine if it is close to the edge of the stem or worse about to fall off you may need .100 longer pushrods to correct alignment. And again all of these things are to prevent engine failure. When you get closer pm me with any questions. Good luck!

 

I agree absolutely! However isn't this a TPI engine?

 

I thought I might write up a very brief tutorial for beginners trying to choose a cam and heads. This is general information and only my opinion.

About heads, you can almost never have enough flow but the size of the runners is critical per cubic inches and application. You want the best flow numbers across all lift points not just max cam lift like .100 .200 .300 .400 .500 lift every flow value at each lift is important. If say a 190cc runner head outflows a 215cc head at near all lift points then it is far superior than he larger head by being more effecient and having more velocity. Kinda see what I am trying to say?

About cams, lift is often the "focus" point people use to say "I got a .700 lift cam"! Ya and so what, there is so much more to the equation! To determine the lift you want you go to the head flow data, if the heads flow no more air after say .550 lift then there is no reason to have more cam lift it's just harder on parts since if you did use a larger cam than that you would need larger valve springs and more spring pressure and this is not very street friendly or for putting any kind of milliage on the engine persay without having race engine type of wear. Make sense?

Duration, this is how long the valve is open. This dramatically affects idle vacuum, idle sound, idle quality, as well as the "powerband" of the engine. More duration leaves the valves open longer which in turn raises the rpm of the powerband and rpm range. One reason is due to overlap meaning often times both the intake and exhaust valves are open at the same time depending on how much duration the intake/exhaust cam lobes have and this also bleeds off some cylinder pressure. To determine what duration you need from the intake vs. exhaust you again need to go look at head flow data. Calculate the percent difference of head flow at each lift intake vs. exhaust, the closer the exhaust numbers are to the intake numbers the closer the cam specs can be relating to I vs. E. duration. If the exhaust is lacking alot in flow increase the amount of duration only on exhaust side of cam spec and if the exhaust flow is still going up on the flow chart past max intake lift you can add some lift on the exhaust side as well. Cams that have the exact same specs for lift and duration are called single pattern cams and if specs are different thay are called dual pattern cams.

Lobe Separation (LSA) This is also VERY important. A more wide lsa will increase idle vacuum and quality where a narrow lsa lessens idle vacuum and quality. A narrow lsa will give more bottom end power say 106-110. A wider lsa usually gives a more broad powerband say 112-114. For a naturally aspirated engine they run best with a 108-110 lsa and a max of 112. For power adders 114-116 is not uncommon. In my own experience 110 has been very kind to me!

I hope this has been helpful! I am no pro, just try to do my best.

 

Very nice "mild sounding'' cam that does provide a good amount of power would be
http://www.lingenfelter.com/mm5/merc...egory_Code=C30

If you are looking for more sound and good performance that does not require a bunch of extras would be the Comp Cams CC503
sound clip(not mine)
ttp://www.youtube.com/watch?v=MceRoG2gVqA


My buddys Lt1 w/cc503 most all bolt ons,3.42s and TUNE.....3800' DA
http://www.youtube.com/watch?v=N3xrMN4poVw

 

This is the EXACT cam I have listed above K08-503-8
Nice times for the conditions!

 

Stock vette L98 heads + LT4 hotcam + bolt on TPI will give over 310-320whp.

Full bolt ons by themselves will do 245-260whp depending on what you get done.

Cam and heads will need intake mods to be worth it. Stock TPI on there will still kill the power.

YOu can try to port out the base as much as you can and clean up the plenum abit and run a mild set of heads with a lower duration cam, something like a 212/218 or 218/224 but I wouldnt go any bigger than that without going to a large tube TPI intake+base.