sorta NFB: what do you guys think of my LT-1/4 setup in this vette?

[azkkn]

i built it with forged pistons, total seal gapless rings, new bearings, crane cams powermax stage 4 cam 538/558@304, custom built ARF 210cc race ready heads, scorpian 1.6 rr,and stud girdles, vortech S-trim, hooker super comp headers, borla exhaust.........and a little more. for now it will be running 9 psi of boost, and eventually it will get 20~22lbs. The compression ratio is 8.64:1. i am dying to start this thing up, its been about 2 years in the making. its also coupled to the tranny with a spec stage 4 clutch, and light weight aluminum flywheel.

[Injuneer]

538/558@304

The cam specs are a little confusing???

[ryan34]

That thing sounds wicked dude!!!

[azkkn]

The cam specs are a little confusing???

.538 lift intake, .558 lift exhaust @ 304 duration. those are from memory, let me find the spec sheet

[azkkn]

That thing sounds wicked dude!!!

thanks, i want to build pretty much the same setup for the camaro, but use different rings, and a little more mild cam, and a procharger instead of a vortech.

[raroZ28]

Sounds nice. Good luck with those TS rings. I hear bad things.

[N20LT4Bird]

.538 lift intake, .558 lift exhaust @ 304 duration. those are from memory, let me find the spec sheet

Usually duration is written first (intake, exhaust) and then lift. The "@" is usually written to show duration @.050. What cam is that?

[azkkn]

Usually duration is written first (intake, exhaust) and then lift. The "@" is usually written to show duration @.050. What cam is that?

Advertised Duration: 296°/304º
Duration @ .050: 234°/242°
Lobe Separation: 112°
Gross Lift: .539''/.558''
RPM Range: 3000-6500

thats the closest one i can find to the specs of mine, and quite honestly i need i am currious now, i bought this cam over a year ago, and cant find the box, spec sheet, or reciept for it. now i am going to start digging for it and ill post it up here when i find it.

[Injuneer]

Wouldn't you want a wider LSA and a little more split on the exhaust duration for a blower cam?

[azkkn]

Wouldn't you want a wider LSA and a little more split on the exhaust duration for a blower cam?

like i said, i dont have the spec sheet. these components were bought to all work with each other. i cant find any info on my cam any where, i think i need to go up stairs in the garage on my days off and look for that spec sheet. you guys have no idea how much this is bugging me. take a look at these pictures on webshots there is my proof

[azkkn]

even after looking at cranes website, i still cant find and cams on there that match it. this is bugging me bad.

[azkkn]

even after looking at cranes website, i still cant find and cams on there that match it. this is bugging me bad.

i found the stupid cam specs

Part Number: 109841 Grind Number: HR-296-2S-12 IG
Engine Identification:
Start Yr. End Yr. Make Cyl Description
1987 Up CHEVROLET 8 ROUGH IDLE, PERFORMANCE USAGE, GOOD MID-RANGE HP, MILD BRACKET RACING, AUTO TRANS W/3000+ CONVERTER, 3800-4600 CRUISE RPM, 10.0 TO 11.5 COMPRESSION RATIO ADVISED. BASIC RPM 3000-6500
Engine Size Configuration
305-350 C.I. V
Valve Setting: Intake .000 Exhaust .000 HOT
Lift: Intake @Cam 359 @Valve 539 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 372 @Valve 558
Rocker Arm Ratio 1.50
Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 37 BTDC 79 ABDC 296 °
Exhaust 85 BBDC 39 ATDC 304 °
Spring Requirements: Triple Dual Outer Inner
Part Number 99846
Loads Closed 115 LBS @ 1.750 or 1 3/4
Open 336 LBS @ 1.210

Recommended RPM range with matching components
Minimum RPM 3000
Maximum RPM 6500
Valve Float 6800
Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 10 BTDC 44 ABDC 107 234 °
Exhaust 58 BBDC 4 ATDC 117 242 °

[fastTa]

Sounds like a pretty decent setup, but if you're going to eventually be "pulleying" this motor to make 20-22 psi, I would definitely consider a cam with much less overlap (higher LSA) and a little more duration and lift split on the exhaust side like Fred pointed out.

The cam you mentioned will work, but it will not take advantage of the boost.

I'm not sure if the shortblock is together already or not, but those Total Seal rings are not good, especially under boost. The theory was good on paper but unfortunately they do not work under real world conditions.

Did you use a gas ported piston?

It is important to properly gap the rings for ideal oil control and to provide a small dynamic compression buffer in the unwelcomed event of pre-ignition and/or detonation, especially under boost. Something like the JE Hellfire or the Speed Pro Hellfire ring sets are good for boost. You should have received a ring gap chart with the pistons.

[N20LT4Bird]

I'm not sure if the shortblock is together already or not, but those Total Seal rings are not good, especially under boost. The theory was good on paper but unfortunately they do not work under real world conditions.

Why are the total seal rings not so good? Is it a ring expansion issue or what?

[azkkn]

Why are the total seal rings not so good? Is it a ring expansion issue or what?

yeah what he said, and i cant gap a gapless ring, so i hope you were talking about the ring gap on different rings than what i have.