Hey, I finally got my car running, loving it. I'm already needing more power. Since I love the idea of extrude hone, im gonna give it a good test.

With the money saved up from this summer, I'm going to get my plenum, slp runners, edelbrock baseplate, and corvette aluminum heads extrude honed. Then compare before and after dyno tests.

After that I'm installing a comp cam, I can't decide between this one...

CCA-08-502-8
* Advertised duration: 269 intake/276 exhaust
* Duration at .050 in. cam lift: 218 intake/224 exhaust
* Gross valve lift: .495 in. intake/.503 in. exhaust
* Lobe separation: 112 degrees
* RPM range: 1,500 to 5,500

or this one...

CCA-08-501-8
Specifications:
* Advertised duration: 264 intake/269 exhaust
* Duration at .050 in.: 212 intake/218 exhaust
* Gross valve lift: .488 in. intake/.495 in. exhaust
* Lobe separation: 112 degrees
* RPM range: 1,200 to 5,200

I'm leaning towards the second, milder cam because I still have a long tube setup and it will be better with the computer. What do you guys think?

 

I would go with the larger cam and cut out the divider walls on the slp runners as far as you can. If you can take out a half inch and port match your plenum and runners you should be able to run the cam into its full rpm range. I'm running that cam with stock tpi intake and stock computer. As for how it runs with the computer i'd say pretty good, i can't say how it did before because i installed that cam when i bought the car and rebuilt the motor (motor knocked). It runs rich at start up but otherwise it runs good. The smell's not even noticeable now that I got a cat back on it. After a minute it cleans out and runs fine. It has a noticeable lope but nothing to radical. There are enough people running this cam on MAF tpi's that there should be some good posts if you read and search enough.

I'm ordering PROM equipment sometime this week and have coated hedman headers at home. Also getting a unconverted LT1 intake later this week so it looks like i'm finally going someplace with my car.

Check out http://www.compcams.com/information/...0HR-10_001.asp on compcams site.

 

I'm definetly interested in the extrude honing. Been considering it myself. Cost is high, though. But why extrude hone the heads. I haven't heard of anyone doing this...

 

i had the second cam in my 9.2 compression ratio 383 stroker motor with trickflow twisted wedge alum heads that cam made a whole lotta bottom end torque best time with that was 13.0 at 105mph gotta have drag radials post ur reply soon after u get the extrude hone done i considered doin it at one time but cost just for the heads was gonna be 700 dollars thru extrude hone in pennsyvania guy said it was suppose to increase flow at 20 percent which is pretty darn good ex. if i had 250 cfms then it would flow 300cfms after extrude hone.

 

ive decided not to extrude hone the heads. $900!!! I'm gonne get the standard abrasives kit and do it myself. I have a set of cracked iron l98 heads that i'm gonna practise on, should be similar to the aluminum heads so thats good.

Roostmeyer: A half an inch? I used Grapeaperacing's calculations for the pressure wave phenomon to ocurr at 5200 rpm on the 3rd set of pressure waves, and i will need runners 19 inches long, as opposed to about 25. So I am going to try to have 6 inches of siamesed runner area. This way that super cool tuned port boost will ocur at the higher end of the cam's power band, and hopefully ill see some wicked power.

The stock tpi's runner length and diameter are tuned to have the boost at about 3000 rpm. This is because the setup utilizes the fourth set of pressure waves and when i plugged in the rest of the stock tpi informatio and left the rpm constant as 'x' 3000 rpm is what the rpm constant equals. Very believable.

So imagine if I'm doing this all right, and i get my torque boost at 5200 rpm!? It would be awesome

Does the boost at 5200 rpm sound good? Or should it be a little lower, I was thinking possibly 4250 rpm. The stock intake still makes power up till about 4500 rpm, so thats like a 1000 rpm residual effect of the pressure wave boost, so 1000 rpm plus 4500 rpm would be 5500 rpm, right at the red line. So cool.

 

I meant 1 1/2" but oh well. If i was going to spend that much i'd port the pis out of them first and let the extrude honing smooth it out and get it the way it wants to flow. I knew it was expensive but $900 I think I'll pass. If you can cut out 1 1/2 of the divider wall on the slp runners and cut out the divider on the plenum side you should be able to cut around 5" out of the effective runner so 19 sounds about right if 25 is stock.

 

Quick question, how does taking off 1.5 inches form them and the dividing wall on the plenum take out 5 inches? I believe you, but I'd just like more details on how.

 

you dont want a big durration, but a high lift will be ok on the cpu. if you go big with the durration, then you will need to get a new prom burned, but if you want more out of what you have in there now, then get the cam with the higher lift.

 

i just about completely cut out the dividers in my slp runners. here are some pics:





and here is the dyno results. this is lt1 cam, stock runners, and siamesed stock base (dyno 14) compared to zz4 cam, siamesed slp runners, and edlebrock base (dyno 15):

 

I wouldn't recommend trying to port a set of al. heads with only one previous head porting experience that you use as an experiment. Head porting is not as easy as it seems and it's a technical science in a way and without many years of experience, I wouldn't suggest trying it on a decent set of vette heads. I would advise spending the money to have them ported by a professional shop with a good rep. Sure if you did it yourself, you might get a few ports to flow pretty good, but it's the consistancy that's important. All of your ports need to flow about 1-2% of each other for you to get airflow balance between your cylinders. This is how you make max power and this is the main reason why CNC'd heads perform so well. This is just my opinion.

 

Have you ever seen the casting inside a set of sportsman IIs??


They are aftermarket "Performance" heads, and granted they probably assume on most high HP applications that they'll get ported, but regardless they're sold to be ran on an engine. I found in my own set of heads a cast "splatter" about the diameter of a nickle, stacked 2 high. Along with many other inconsistancies and irregularities.

If you measure your port work (some use an wrench) to make sure dimensions are as close as possible, you're not going to "ruin" any heads. With a profiled valve guide, a gasket matched port enterance, and some light bowl blending, its all gains with a steady hand.

just my opinion

 

thanks for the info.

mr23, did you have to remove the exterior walls in order to siamese those runners? Or did you just use a long grinder or something? I am really interest ed in siamezing them completely.

 

i used a 6" long aluminum porting bit. had to buy the 4 pack. different shapes. cost $180

 

wow mucho dinero
o well, maybe i can custom tune my runners with those though.

 

i had them from siamesing my stock base and porting the plenum. so i have made good use of them.