Hello all,
Well I have been going back and forth with myself for 2 weeks about a decision and I figured I would get some fresh perspectives. Here's the deal - I have a 383ci stroker motor, scat crank, eagle rods, JE pistons. It has Trick Flow twisted wedge heads, I have over 900.00 worth of work in the trick flows (on top of the price of the heads), they flow around 270cfm on the intake side at roughly .550, the chambers are cut to 62cc's. In the current configuration I netted a 11.5:1 cr. The car ran extremely hard, I installed a TPIS ZZ-9 camshaft (degreed in) and an accel Super Ram (port matched). I now wish to lower my compression ratio I am going to purchase a set of AFR 195's with the 72cc chamber. My questions is this - I really want the competition package (full CNC porting 282cfm on the intake) but given my current budget I may have to settle for the street package (loses 20cfm on the intake side) Racer net on the comp package is around 1900. the street package is around 1200. What should I do? Help me out guys...I still want the car to run hard (it'll still have around 10:1 with the 72cc's) I may try to sneak an intercooled supercharger on it once i have more money...
WHAT TO DO?

 

Why not keep the Trickflow's and just grind the chamber a little bigger. Just do a little valve unshrouding. What head gasket are you using? How far is the piston down in the hole?

 

The early Trick Flows don't leave alot of extra material to work with (one of my pushrod tubes has a sleeve in it due to this) to try and go from 62 to 72 is kind of a tall order. Besides the AFR's have a much thicker deck and the aluminum they use is not as soft as the Trick Flows.
Anyway the point is I have already decided to get rid of the trick flows (up for sale.....) I was just wanting an outside opinion of weather or not to spend the extra dough and get the full CNC job on the AFR's.
-Mike

 

Why do you now want to lower the compression ratio?

 

I want to lower the compression ratio for a few reasons. 1) I would like to know that i can cruise my car around without having to worry about octane. "Hey wanna race..-okay let me go change gas real quick" 2) I would eventually like to add some kind of forced induction. I know 10:1 is still quite high but I was planning on using an intercooler and water/alcohol injection to curb detonation.
This is great guys but I was really just looking for a -"get the expensive one's" or -"save the money you'll never know the difference" answer.
thanks
-Mike

 

If your engine is built right you should have no problem with a 10.5:1 compression ratio and pump gas. Lots of people here in So Cal with that ratio and running on 91 octane.

I have to agree on your Trick Flow heads. They seem fo flow pretty good. I sure would look hard into making the chambers a little larger. Maybe a slightly thicker head gasket and some enlarging of the combustion chamber would do the trick. Allen

 

Okay this is getting a bit silly. Your right 10.5:1 on pump gas is no problem. BUT as I stated in my original post that you obviously didn't read I have/had 11.5:1. Just so you know it is built right I was able to run that motor pretty hard on 91 octane and a bottle of amsoil octane boost. I could putt around on straight 91 but since it is not my daily driver I didn't realy do it that often. I can tell you quite a bit about the quality of work done to my engine if you really want to know. One thing I am wondering about, do most people feel that the Trick Flow heads are better than the AFR's? These are an early set...the aluminum is kind of soft, softer than what most companys use. This particular set flows very well...but it took alot to get them there (alot more than I should have put in these). I just don't feel that I was making significantly more HP with 11.5:1 than had I gone with say 10.5:1. I have the timing rolled back quite a bit in the computer...this thing gets almost no advance to keep it from pinging. I have often wondered if I could actually get it to run faster with less compression and more timing. Anyway keep the posts coming I am interested in what everyone has to say.
-Mike

 

Ok, yes ( if you're having to run a lot of knock retard to avoid pinging at 11.5:1 with the available fuel) you probabily will make more power, certainly more usable power on 91octane if you lowered the cr and ran the timing at a more optimum advance setting.
You should decide if in fact you're going to supercharge it. If so I'd lower it to 9.5:1 . Will allow much more boost on 91 octane. even with a intercooler.

For $600 extra bucks for full CNC porting and 20cfm I'd say go for it.

Or..... have you considered keeping your combination and wringing the most out of it on the available fuel with a Water/Alcohol injection system added to avoid detonation.

www.aquamist.co.uk
www.carrollsupercharging.com

 

I say take as many cc's ( 6cc's) as you can out of the chamber and run them. Then when you decide to get a supercharger then get the 72cc AFR non CNC ported heads. You don't need the extra 20 cfm flow with a forced induction. Forced induction has a way of covering up or masking the head flow, if you know what i mean.

 

There isn't a whole lot of material there until you run into the coolant passages. I suppose I could get a few cc's off there...get it close, but I don't want to ruin the burn characteristics of the chamber.
-Mike

 

HELP ME I NEED HEADS!!