I made 450 rwhp and 470 rwt with stock Edelbrock oval (296 at max valve lift) and stock Air Gap intake. solid roller .646 .653 242 and 248 at .050

I am going to have the heads and intake worked. It may sound like a dumb question but am I looking for max flow possible in the heads, or will I kill some velocity. I think I will need approx 330 cfm to get to the power level I want. Is there any reason not to go for 350 or more, or can I mess things up.

Considering a bigger cam 250 at .050

The car made max power at 6100 rpms, would like to move this up to 6300 or so.

 

You may want to look at the extrude process. They run a abrasive material that is backed by pressure. This removes material evenly and suppose to increase cfm and the efficiency since the abrasive material is a "liquid" just like the air that will be flowing through the heads.

http://www.extrudehone.com/

I have never used it nor do I know anyone that has. I have only read about it. It sounds neat :)

Here is some text from the website:

"...In addition to meeting the rigid requirements of professional race teams and production automotive manufacturers, Powerflow is an effective process for the performance enthusiast. Mustangs, Corvettes, muscle cars and high performance imports offer many excellent performance enhancing opportunities for Extrude Hone. Increased custom airflow can be tailored specifically for a Powerflow application. Results have demonstrated that such increases can exceed 30 percent on aluminum intake manifolds and 25 percent on cylinder heads.

Another popular application is strengthening a component. The process eliminates stress risers, such as burrs, from edges and surfaces where a crack can occur. Extrude Hone routinely processes gears and brake rotors to provide a uniform edge that significantly improves the dependability and life of highly stressed components...."


[Modified by 69stingray, 4:13 PM 10/9/2002]

 

There is an important relationship between the cross-sectional area of the port, the high-lift flow, and horsepower. Generally, the high-lift flow can only be substantially improved by increasing the cross-sectional area of the port above the valve. High-RPM power may go up or down depending on the new port area to flow relationship. Low-RPM power will go down.

You may want to trust Edelbrock on the port cross-sectional area that they chose, and just improve the finish in the port to gain some extra flow. The Extrude-Hone process sounds interesting. Then design a cam to take advantage of the new flow and port dimensions. This automatically shifts the torque curve up in RPM.

Can't tell you more without running some numbers. Just don't guess.

 

69 NOX RATT, I think your going to need a cam in the 255-260Deg@.50
Plus head porting and maybe more compression to get 500+RWH. And a single plane intake.
I'm looking at doing another short block, and thats what I'm shooting for.
So I'll be watching your progress.
It's not that hard to get that kind of power out of a 454. But making it streetable is the tough part.
Now if I only had the money to build a 540 or 572. Getting 500+RWH would be easy. :)

 

Glenn454: I think you are probably right, especially since I am trying to do it through the mufflers. I made 450 through the exhaust, so I would probably be at 460-480 with open headers. I should be able to make 500 RWHP with open exhaust pretty easy with some head, intake and cam work. It wil be tough to do through the exhaust and still keep the motor as streetable as it is now. I am not going to go with a real big cam, that is why I got the Fogger. Once the motor is done I will play with the NOS. Probably keep it sorta mild with a 150 shot. :chevy

A 540 would make things easier

 

How big is your motor right now? With the kind of power you are making now it shouldn't be too much of a problem to get it up to 500rwhp. How much money do you want to spend?

What have you done to your motor to enable you to run a 150hp nitrous setup?

Steve

 

This is not rocket science. You want 50 hp more? If was my money I would contact CNC for your heads. You did not mention CR. Can you add a full point? What quench are you running. The air gap is nice below 6,ooo. For you a single plane might be the thing. You are close to your goals. Fine tuning and a few parts will get you there. I checked out the Extrude hone. It does a nice job but not enough to make the difference you are looking for. It could get expensive getting all your parts to match. The porting alone from CNC will get you most of the 50 hp you want. Others have been where you want to go. Find out what they know. Don't forget the DD. Good luck. Please keep us posted.

 

The motor is 460 inches. It should be good for a lot more than a 150 shot, but that is all I will run. I have it through a Sportman Fogger.

High performance passenger block, 4 bolt with ARP studs, L-88 rods, Milodon bolts, factory steel crank, JE pistons set up for 250 shot, O ringed block. ARP head bolts. Seperate fuel system from the tank for the NOS, pump, regulator etc.

10.25 to 1 compression

I will be doing the same thing you did Steve with the one gallon fuel cell. I already have a completely dedicated fule system.

I have a very good connection for having the heads done.

 

You've got a really killer short block.

Out of curiosity, what brand/type of rings and ring gaps?

I think the intake is hurting you right now. When you get your heads ported, the manifold will hurt you even more. A good single plane is the hot setup. You have a pretty healthy cam right now and I doubt 8* intake duration will make a big difference.

What size is you carburetor?

I wouldn't worry about negative effects from porting your heads. Your motor is more than big enough to handle whatever flow those heads end up with. (Just make sure they flow more when done!)

Steve

 

Steve,

There is no doubt you are right about the intake. I would go to a single plane in a second, except it won't fit under my hood. I have a L-88 hood and even after a lot of custom fitting my drop based K and N extreme top is still costing the motor 35 HP at the wheels. I do not want to but I am going to have to raise the hood an inch to make up for this. I do not want to raise it any more than that. Since the car is a street car and not a race car I will sacrifice a little performance to keep the stock look.

I run stock rims on 235 60 15's Firestone Firehawks, with a luggage rack. It is as much as a sleeper a yellow L-88 hooded 69 vette can be. I prefer the stock look, or all out pro street.

The guy who is doing the heads and intake, helped start Air Flow Reasearch a number of years back. He is a friend of a friend. In my buddies 56 (Vette) he flowed each individual cylinder from carb to valve and out. He is going to do the same to mine. He is an older guy who still likes to get his hands dirty every now and then.

The rings are JE. I live less than a mile from JE and went over to the shop and talked to their head tech guy for over an hour about pistons and stuff. He looked up my order in the computer and said they would good for a 250 shot plus, which is what I ordered. I got a good education that day.

Groove Land
Top .064 .325

2nd .064 .180

Bottom .188 .100

662 grams

The carb is a Jet stage 3 annular discharge Holley 850 flowed to 920-930.

You do not think changing the cam will gain much? I know you have a lot more dyno time than I do, but I thought the extra duration would help a bit. The cam I have is pretty high lift but pretty short duration for a 460 in motor. :chevy


[Modified by 69 N.O.X. RATT, 4:33 PM 10/17/2002]


[Modified by 69 N.O.X. RATT, 4:34 PM 10/17/2002]

 

Here is a idea for you to consider. I have taken a dual plane intake, cast iron bowtie rpm range 1500-6500, and machined the divider out of the center of the intake! I've also done this on several aluminum ones since, but have not done any dyno testing on those. I race stock cars, so rules limited me to 360 ci or less, cast iron heads, single plane intake, 750cfm or less carb, .530 lift or less on the cam/valves. I had a 355sb, bowtie cast iron heads, .525 lift 252@.050 dur cam, 11.8-1 compression, 700 holley that was modified and actually flowed 780cfm, and the cast iron bowtie intake(marine). The motor made 432hp@6200 rpm with the intake stock as cast. After finding another cast bowtie int., at a swap meet cheap, I decided to experiment with it. I ported the runners to match the heads, and then machined the divider out of the center. I then radiused the top of the plenum down to the connecting runners and rounded off the edge of the step in the floor. With just the intake change, I gained .4-.6 of a second per lap! At the end of the season I took the engine to the dyno shop and ran pulls with the modified intake and the stock intake. The modified intake made 473hp@6900rpm and had 380+tq from 2900-5700rpm. Swapped intake back to the stock one and pulled 431hp@6000 rpm and only 383tq at its peak. The modified intake made 42hp more, 33tq more at its peak, and gained a useable 900rpm! I have done this same mod to several aluminum intakes, and all of them have made quicker ets or lap times, but I do not have any before and after dyno results from them to know how much better they really are. Just a little "secret" that has worked for me, if you want to try it or not is up to you, I just thought I'd share it with you. :cheers:

 

I forgot to ask, what carb are you running? There could be some hp there also! :cheers:

 

I plan on taking out the divider, that can be a good HP trick.

The carb is a 850 DP flowed to 920-932

 

Isn't it nice knowing the right people? It sounds like the guy that will be doing your heads knows what he is doing. This will be a real bonus.

I use J&E pistons and rings(repackaged Speed-Pro). I really like their stuff. I am a little confused by your specs on the rings. Are you saying that you file fit the top ring to a .325" endgap and the second ring to a .180" endgap?

I can't urge you strongly enough to get a single plane manifold. I have picked up as much as 60hp on a 482" motor I did back in the late '80s. This was over a stock Chevrolet aluminum big port manifold with the center divider removed.

If you go with more duration you will give up some of the driveability that you have now. I wouldn't hesitate to try a larger cam on the dyno where you could evaluate the results with relatively little hassle. I just hate making time consuming changes that might not give the results you want.

Have you ever posted any pictures of your car and engine? If not, you should. Incidently, my '69 has a factory L-88 hood and I was able to fit a Holley Strip Dominator manifold under it with no problems.

Steve

 

The single plane issue has bothered me for a while. I keep going back and forth and then I think that is what that blue tank behind the passenger seat is for. Maybe in the future I will. Mountain motor tried to convince me to use an old torker 2-0 (carb sits sideways) I have. They are not real good in the low end and I have went through the hassle and expense of plumbing the fogger into the RPM Air Gap, but that guy really knows his stuff. The motor should be good for 650 rwhp and close to 700 pds of tq (150 shot) when I am done this time. Is this enough with a ROD and 3.70 rear gears, probably not :lol:

The specs on the pistons are the groove dimensions and how far down on the piston from the top of the piston the grooves are moved down.

The first groove is moved down .325 inches from the top of the piston. The piston has a 21 cc dome.

I keep trying to get a home page, but they are full. I have had somebody else post them for me a while back. If you know of a way without having a home page let me know and I will the flod the web site with photos :chevy

 

I don't think you should worry about giving up the low end by switching from a dual plane to a single plane. You have a big block with a crap load of torque. I doubt that you would even be able to notice any low speed driveability difference between the two styles.

I am still wondering about you ring gap. Do you remember what it is? The top groove is down nice and low - perfect for nitrous but the ring gap is just as important.

I don't know any way around the home page deal.

Keep me posted on your progress.

Steve

 

I know what you are talking about now, little misunderstanding. We went 4 X 4.280 .030 over 454.

 

John,

I have a L88 hood with the cold air package. I have RPM performer intake with a 1/2 nitrous plate. I had to trim the screen that fits on top of the carb some. But it fits.