The engine is out....

[TraceZ]

What is the approximate amount of power before you need duals?

I dont know if there is a required power level for true duals. I've got a build in the works that will include a 396ci bottom end and a ported top end and I've always intended to run it through midlength headers and my Borla catback. It never even occurred to me that the Borla would cost me power on that setup. Even if it did, it has an e-cutout in it I could open. And if it was still costing me horsepower, I'd still keep it. I like it too much to give it up over a few ponies when I'll be pushing over 450 to the wheels anyways.

I really dont like the true duals that end before the rear axle. I used to have true duals on a 87 Z28 I had years ago, but that setup went over the axle and under the bumper. That was pretty cool... long tubes, twin high flow cats and true duals over the axle ending in a couple little high flow mufflers that you could see strait through. It sounded totally bad to the bone. It was expensive, though. It was all hand made and had a center section that could drop out for transmission access.

[jerrysta]

I had a Borla that I always ran open and it sounded great, but my build is similar to yours (388 and ported trickflows) and I am trying to get all the power I can out of her. I understand your thinking on the subject totally. I will be using Pacesetter longtubes. I admit I was a little nervous about the different sounds, but I heard some clips from the internet of the exact set up I will be running and it sounds great.

I do admit I will miss the exhaust tips, but I was not a fan of the Borla tips anyhow. I will be dumping the exhaust. I am thinking my HP numbers will be similar to yours so maybe my thinking is overkill.

What are you hoping to run with you 396? I'll tell you what I'm thinking after and we can see how much crack I've been smoking.

[fastTa]

What is the approximate amount of power before you need duals?

Way more than you'll be making.

The most important thing when tuning an exhaust system is to attempt to obtain maximum primary and secondary velocity while eliminating any pressure losses present from the exhaust valve to the end of the exhaust. Primary diameter, primary length, equalness of primary lengths, primary bend shape, collector internal transistion shape and length, etc., are all governing factors.

Given this, the most important part of an exhaust system is the leading side of the exhaust system; the headers and collectors. The catback is also important, but not quite as much as the headers and collectors. Even so, a y-pipe will still make more power on a typical street application and I'll explain below.

Primary diameter and primary length are 2 of the most important in regards to primary gas velocity and will heavily dictate low to mid-range power. Collectors are next on the list of importance and they help control secondary velocity, but not near as much on a typical street application. When a collector is open to the atmosphere as in a true drag car, the collector predominantly dictates secondary velocity. However, in a typical street application where you are using a "catback" type system, the collector is obviously not open to the atmosphere and it is therefore not as much a dicating factor in secondary velocity. The catback will predominantly dictate that.

The x-pipes and h-pipes are a great design on paper but I have yet to see any proof or solid documentation that they actually work. Y-pipes on the other hand, have been substantially proven to show an increase in power over true duals in most typical street applications.

Start making over 1500 hp, and then you may want to consider ditching the y-pipe.

[TraceZ]

What are you hoping to run with you 396? I'll tell you what I'm thinking after and we can see how much crack I've been smoking.

I have no idea. It depends on the suspension setup and how much the car weighs. It is pretty heavy and I refuse to strip it for weight. I just want to have fun building it and have it be faster than 99.9% of all the other car on the streets in town.

I'd love to beat my dad's Cutlass in a brief side-by-side on the interstate.
He has a 1983 Hurst Olds with a .030 over 455 under the hood. The heads are the hi-po "C" casting and are ported and polished. He is on his second rearend and transmission already. Loads of torque, but it is even heavier than my car and cant go around a corner to save its own a**. It has a Edelbrock cam that he says is pretty big and a matching Edelbrock intake. Sitting on top is a Holley 750 double pumper. It is fired by the stock type HEI with a MSD box and blaster coil. It runs with the stock exhaust manifolds from the original 307 and a high flow catback.

This spring I'm doing 1LE swaybars, driveshaft and sub frame connectors. Hopefully the headers will be a summer project. Then, I can start thinking about puting some of these engine pieces together for the following spring.
His car might be faster for the time being, but he could never beat me around a corner in a million years, especially after I get my springtime mods on.

[jerrysta]

Got ya. That's kind of how I feel. There is always someone faster. I just want enough power to scare the s%&t out of myself.

Well I'll tell you anyway: I hope to hit upper 11's. I know it will run low 12's, or at least I'm really confident that it will.

I broke my wrist, which slowed things down a bit, but in my garage I have a new panhard bar, LCA's and brackets, a tranny cooler, MSD6AL, new wires and plugs, blaster coil, headers, torque converter, fuel injectors and I have already installed a new fuel pump to go along with the motor.

I hope it all works together.

[Kevin - Blown 95 TA]

I have no idea. It depends on the suspension setup and how much the car weighs. It is pretty heavy and I refuse to strip it for weight. I just want to have fun building it and have it be faster than 99.9% of all the other car on the streets in town.

I'd love to beat my dad's Cutlass in a brief side-by-side on the interstate.
He has a 1983 Hurst Olds with a .030 over 455 under the hood. The heads are the hi-po "C" casting and are ported and polished. He is on his second rearend and transmission already. Loads of torque, but it is even heavier than my car and cant go around a corner to save its own a**. It has a Edelbrock cam that he says is pretty big and a matching Edelbrock intake. Sitting on top is a Holley 750 double pumper. It is fired by the stock type HEI with a MSD box and blaster coil. It runs with the stock exhaust manifolds from the original 307 and a high flow catback.

This spring I'm doing 1LE swaybars, driveshaft and sub frame connectors. Hopefully the headers will be a summer project. Then, I can start thinking about puting some of these engine pieces together for the following spring.
His car might be faster for the time being, but he could never beat me around a corner in a million years, especially after I get my springtime mods on.

If you're building a 396, you need to change your sig (project 383 stroker). I may have some parts to throw you if you are interested - 30# SVOs & probably my 42# Lucas matched set injectors, blaster coil, LT4 Extreme duty timing set, LT4 head gaskets, Fel-Pro intake gaskets, crank scraper, 12 pt header bolts, ARP 12 pt head Bolts, Federal Mogul Premium (OE) plug wires, etc. Some of it new, some of it slightly used in EC. I just haven't got myself organized enough to post it on the FS forums yet.

[TraceZ]

If you're building a 396, you need to change your sig (project 383 stroker). I may have some parts to throw you if you are interested - 30# SVOs & probably my 42# Lucas matched set injectors, blaster coil, LT4 Extreme duty timing set, LT4 head gaskets, Fel-Pro intake gaskets, crank scraper, 12 pt header bolts, ARP 12 pt head Bolts, Federal Mogul Premium (OE) plug wires, etc. Some of it new, some of it slightly used in EC. I just haven't got myself organized enough to post it on the FS forums yet.

I havent researched injectors yet. I still need fuel rails too. I was planning on going with a vented opti on the new motor, so I can use the LT4 timing set. I have a spare 94 timing cover I could trade for a 95 if anyone has one and is willing. I also have a very lightly used 1994 LT1 timing set I could use in any possible trades. I have a spare stock TB that I'd like to have bored out to 52mm as well. Let me know what you think would work for me and what you want for it.

My intention is to build a drop in motor complete with brackets, accessories and drive belt before I even touch my car. After the new motor is in, I'm going to do a cosmetic rebuild on the original motor, make it look really pretty and then put it on display in my home office. It only has like 57,000 miles on it. It will make a good conversation piece and it might be nice to have it with the car in another 10 years for collectability value. My car is pretty rare having the M6 in a Z28 convertible. It might be worth something some day to have the original motor with low miles.

[Al 96 Ram Air T/A]

Hey Jerry...been following the project, looks great!

What did you do to address the timing chain? Stay with the stock LT1 or upgrade?

I've heard most choose to use the Cloyes but that means ditching the stock water pump in favor of an electric unit.

[jerrysta]

Bought a brand new stock timing set and the builder is going to put a teeny-tiny hole there to allow it to stay oiled nicely.


Less than two weeks until she's back in my hands.....can't wait to see what he does with the heads!!

[Kevin - Blown 95 TA]

Bought a brand new stock timing set and the builder is going to put a teeny-tiny hole there to allow it to stay oiled nicely.


Less than two weeks until she's back in my hands.....can't wait to see what he does with the heads!!

thought that's what the holes in the two front plugs are for???

[fastTa]

Bought a brand new stock timing set and the builder is going to put a teeny-tiny hole there to allow it to stay oiled nicely.


Less than two weeks until she's back in my hands.....can't wait to see what he does with the heads!!

There's no reason to tap or drill larger holes into the oil galley on either side to provide more lubrication to the timing set. This is normally a procedure only done when people use gear drive timing set. It is completely uneccesary for a chain.

[95TransAm]

There's no reason to tap or drill larger holes into the oil galley on either side to provide more lubrication to the timing set. This is normally a procedure only done when people use gear drive timing set. It is completely uneccesary for a chain.

I totally agree. I currently am attending an automotive tech school, and finished up my first of two phases of engine management systems classes. From everything that I have learned, there is no reason for another hole to be drilled. When the timing gears are meshed, exactly like what kevin said, then the procedure sometimes is done. Engines are also designed a specific way. The oil galleries are designed to allow the oil to drain back down towards the crankcase effecieciently, even more so in our LT1's than many other engines. To me, it's just something I wouldn't tamper with until I was putting down some extreme numbers to the rear wheels.