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Crate Engine Horsepower

Started by _LH350_ , Feb 03 2006 08:42 AM

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8 replies to this topic

#1 _LH350_

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Posted 03 February 2006 - 08:42 AM

Guys,

I have bought one of the Suburban s/b crates which is said to be rated at 375hp (at 5700) and 407ft pounds (at 4300).

I was given a dyno sheet whcih shows these figures and refers to the Edelbrock Performer manifold, Comp Cams .470/.480; 224/230 and Vortec L31 heads.

I was told the engine has flat top pistons as well.

Do the output figures seem realistic or optimistic?

I have been told the vortec heads with their small (64cc) chambers run quite high compression (say 10:1) which might account for better than normal figures but guys I have spoken to say they have never seen vortec heads make over 300hp at the flywheel.

Anyone with any ideas?

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#2 dattoman

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Car:LX SS , 76 Cadillac , 3 x dattos
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Posted 03 February 2006 - 12:32 PM

In theory
My 383 with 10:1 comp
RPM Performer heads
RPM Performer manifold
Crow cams 1622 cam
1.6 roller rockers
750 vac sec carb

This engine in theory makes 398hp on the desktop dyno

HP happens in the heads
If your unsure get someone to put it on the dyno and if it doesn't make what your importer has promised tell him you want your money back

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#3 _Bedford_

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Posted 03 February 2006 - 08:47 PM

Off Topic : I know what a normal dyno is. What's a desktop dyno? Is it a program?

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#4 dattoman

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Car:LX SS , 76 Cadillac , 3 x dattos
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Posted 03 February 2006 - 08:52 PM

Yes a virtual program where you plug in all your known figures and it gives you a theoretical power and torque curve

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#5 _Bedford_

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Posted 03 February 2006 - 08:56 PM

that's cool
what's the program called?

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#6 _LX406_

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Posted 03 February 2006 - 09:40 PM

Spend a few bucks and put the engine on the dyno before it goes in the car. it will be run in nicely, and you will know your power output exactly.

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#7 _seperf_

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Posted 03 February 2006 - 10:11 PM

Guys,

I have bought one of the Suburban s/b crates which is said to be rated at 375hp (at 5700) and 407ft pounds (at 4300).

I was given a dyno sheet whcih shows these figures and refers to the Edelbrock Performer manifold, Comp Cams .470/.480; 224/230 and Vortec L31 heads.

I was told the engine has flat top pistons as well.

Do the output figures seem realistic or optimistic?

I have been told the vortec heads with their small (64cc) chambers run quite high compression (say 10:1) which might account for better than normal figures but guys I have spoken to say they have never seen vortec heads make over 300hp at the flywheel.

Anyone with any ideas?

i feel it sounds a bit high by about 25-30 hp ??? maybe wrong

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#8 _seperf_

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Posted 03 February 2006 - 10:14 PM

In theory
My 383 with 10:1 comp
RPM Performer heads
RPM Performer manifold
Crow cams 1622 cam
1.6 roller rockers
750 vac sec carb

This engine in theory makes 398hp on the desktop dyno

HP happens in the heads
If your unsure get someone to put it on the dyno and if it doesn't make what your importer has promised tell him you want your money back

plus a nice fat torque line .

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#9 LS1LX

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Posted 04 February 2006 - 08:22 PM

Spend a few bucks and put the engine on the dyno before it goes in the car. it will be run in nicely, and you will know your power output exactly.

Its the only way to do it and give it a tune, but $500-600 for a day of play aint cheap.

BTW desktop dyno figures are a bit happy most of the time, I find them 20HP happy normally.

back on topic, I question these reco vortec engines, they sound good on paper but when you look into them there nothing too flash.

If you dont put it on engine dyno, stick it on a chassis dyno when its running, if its got a manual behind it you should see around 320-330HP at the treads, if its got a big auto behind it your be pushing around the 280-295hp at treads. I know this isnt accurate but if your another 50hp shy and only make 200-250hp at the wheels then something wrong, it aint no 375hp engine.

Still 407ft/lbs is decent TQ for a small cammed 350. Ask for a copy of the dyno sheet.