This description may show my ignorance but here goes: Currently installed in the car when I bought it with <10k miles is a 91 vintage GM Gen IV 4-bolt 454/425 crate engine with 4.25 or 4.495 bore and rectangular port open chamber 118cc/IP 325cc cast iron heads (valve size: 2.19 int, 1.88 exh) with 8.5-1 compression to run on pump gas. Cam is hydraulic, probably (not sure) .500 int and exh; duration at .050 lift is .222 int and .221 exh. Intake is a GM hi-rise restangular port aluminum (not sure if single or dual plane) used on the 72 454 hipo camaro with a new 850cfm dp Demon carb and Hooker SC headers. Engine is supposedly blueprinted and the heads have supposedly been polished and ported (how can I tell?). Can anyone do a desktop dyno to verify the 425HP or more claim? What would you do to this engine to get more HP? :D :D

I also posted this in the Engine Mods forum. Thx for your help! :cheers:


[Modified by Marks69BB, 2:49 PM 10/2/2001]


[Modified by Marks69BB, 4:13 PM 10/2/2001]


[Modified by Marks69BB, 4:19 PM 10/2/2001]


[Modified by Marks69BB, 11:13 AM 10/3/2001]

 

You might need a bit more info to get accurate results from desktop dyno, your info is good but vague for that software.

Gen Vi 454 425hp engine stat's:
The 454 HO makes 500 Ft/Lbs of torque with its rectangular port open chamber cylinder heads. With 118cc combustion chambers, the modest 8.75 to 1 compression ratio loves today's pump premium and has no appetite for lead, octane boosters or other fuel additives. Its 2.19" intake and 1.88" exhaust valves and high lift .510"/.540" roller cam let it breath with the best of the early muscle car motors.

Horsepower ........................................ ..425 @ 5250 RPM
Torque ........................................ ............500 Ft Lbs @ 3250 RPM
Maximum Recommended RPM ........5500
Compression Ratio ..............................8.75:1

Block ........................................ ..............12550307 - Cast Iron 4-Bolt Mains
Crankshaft ........................................ ....14096983 - Forged Steel
Connecting Rods .................................1019892 2 - Forged Steel
Pistons ........................................ ............10215019 - Forged Aluminum
Piston Rings ........................................ ..12523921
Camshaft ........................................ .......24502611 - Hydraulic Roller
Lift: .510" Intake, .540" Exhaust
Camshaft Duration @ .050" ...............211° Intake, 230° Exhaust
Timing Chain ........................................ .3891519 - Single Roller
Cylinder Heads ......................................14 096801- 118cc
Intake Valves ........................................ .14097045 - 2.19"
Exhaust Valves ......................................14 097049 - 1.88"
Valve Springs ........................................ .14097002
Rocker Arms ........................................ ...12523976 - 1.7:1 Ratio
Flexplate ........................................ .........10185034 - 14" Auto Trans
Torsional Damper .................................1409702 3 - 8"
Valve Lash ........................................ ......Net Lash
Fuel ........................................ ...................92 Octane
Spark Plug ........................................ .......MR43T
Ignition Timing ......................................4° BTDC

What would I do to get more hp?
Dunno not a BB man, however...
I would look at:
- double roller timing chain
- roller rockers?
- rpm air gap intake
- Felpro thin shim head gaskets ( will bump you to 9.0-1)

[Modified by 1976C3, 4:09 PM 10/2/2001]


[Modified by 1976C3, 4:14 PM 10/2/2001]

 

What other info do I need to get?

 

I can not remember all the details needed, but stuff like cam specifics, valve int/exh compression, engine bore, head mod's, etc...

I modified my prior post to show what info I found on your engine. If that is your engine 454/425... you have a roller cam not hyd.. and other new info for you.

 

From what I've been able to gather, they weren't using roller cams in the early 90's crate engines. If anyone knows different or how I can tell I would appreciate tips. Also, the bore could be 4.25 instead of 4.495 for this block. Keep the info coming...... :smash:


[Modified by Marks69BB, 4:41 PM 10/2/2001]

 

My info came straight off a gm page on the gen VI 454 crate engine *shrug*.

 

It sounds like that motor has got you down :sad:
I'll take it off your hands for free :cheers:


[Modified by 71coupe, 3:41 PM 10/2/2001]

 

He's got a Mark IV, not a Gen VI. Gen VI is the roller motor.

 

ahh mark VI, ok that clears up the confusion. I was simply going with the gen VI because he said that was what it was.

Thanx for clearing that up.

 

Mark I have a Gen V 502 version of your motor. You are right we have the flat tappet hydraulic cams in our motors. I posted yesterday about head mods because these heads can really flow the air if prepped right but we do have a non-adjustable valvetrain so if we were to run another cam we need to convert to the mark iv system. Also the size of your engine is stamped on the side of your block down near the block coolant drain plugs. I have an 8.2 stamped down ther on both sides.

 

ttt - No one has any suggestions?



[Modified by Marks69BB, 11:12 AM 10/3/2001]

 

Mark - What exactly is wrong with the motor? Is it a dog out of the hole, or is it signing off too early? It sounds like it's not up to your expectations for a rat.
The route to more power is more compression & cam (you already have the displacement)
Before you do anything, you need to keep in mind that the limitting factor is the low compression of your motor. You will need to address this factor first before you start spending your hard-earned cash.

 

Some quik hp gains...

I dont know BB engines, but like others said your low compression would be the 1st thing I look at.

Cam upgrade
Head upgrade
Roller Rockers
Intake Upgrade

You got the engine it just needs to have top end mod's to wake it up more. Then look at your drivetrain. What gears are you running, etc? Getting the power to the wheels is important also.

Thats my suggestion.

 

I'm just trying to understand what I've got now and what, if anything, I can do to get the motor in the 500hp range. I will be doing a chassis dyno in early Nov but with all of the talk of 9+ -1 compression while still using pump gas, I was wondering if the GM heads and intake are hurting the engine's potential or if other things like a roller cam would be beneficial. This is for info only right now until I get it dynoed, but I'm sure many others have built these same 454s well past 500hp.

 

Your single biggest increase in power would come from a better cam. If the engine is due for a rebuild (or you just want the most power), a higher cr would be benefitial. Post more info about your car and how you use it, i.e., tranny, rear gears, mostly hwy or in town driving, etc., and you'll get more specific suggestions.

 

Right ! What's trans., gears, driving, etc. & hood?

 

Everything's in my sig. I drive this car 3-4 times/wk and in local cruise-ins/shows and run it at the strip about every couple of months. I just don't like the idea of being whipped by M5 BM'rs, C5s, and even new F bodies since I have a big block and could waste em if it was built properly. I'd like to be able to keep up with vipers. I've run it at the 1/8 mile in the mid to high 8s but that was with bad 60 times due to my newbie skills and the old crappy hard tires I had on at the time. That's been changed with new BFG 255-60s. I've considered changing the rearend but figure the engine would be the better place to start. As always, thanks for the help! :cheers: